[PATCH 0/12] memcg updates v5

[PATCH 0/12] memcg updates v5

[KAMEZAWA Hiroyuki]

Hi, I updated the stack and reflected comments.
Against the latest mmotm. (rc7-mm1)

Major changes from previous one is 
  - page_cgroup allocation/lookup manner is changed.
    all FLATMEM/DISCONTIGMEM/SPARSEMEM and MEMORY_HOTPLUG is supported.
  - force_empty is totally rewritten. and a problem that "force_empty takes long time"
    in previous version is fixed (I think...)
  - reordered patches.
     - first half are easy ones.
     - second half are big ones.

I'm still testing with full debug option. No problem found yet.
(I'm afraid of race condition which have not been caught yet.)

[1/12]  avoid accounting special mappings not on LRU. (fix)
[2/12]  move charege() call to swapped-in page under lock_page() (clean up)
[3/12]  make root cgroup to be unlimited. (change semantics.)
[4/12]  make page->mapping NULL before calling uncharge (clean up)
[5/12]  make page->flags to use atomic ops. (changes in infrastructure)
[6/12]  optimize stat. (clean up)
[7/12]  add support function for moving account. (new function)
[8/12]  rewrite force_empty to use move_account. (change semantics.)
[9/12]  allocate all page_cgroup at boot. (changes in infrastructure)
[10/12] free page_cgroup from LRU in lazy way (optimize)
[11/12] add page_cgroup to LRU in lazy way (optimize)
[12/12] fix race at charging swap  (fix by new logic.)

*Any* comment is welcome.

Thanks,
-Kame

[PATCH 1/12] memcg avoid accounting special mappings not on LRU

[KAMEZAWA Hiroyuki]

There are not-on-LRU pages which can be mapped and they are not worth to
be accounted. (becasue we can't shrink them and need dirty codes to handle
specical case) We'd like to make use of usual objrmap/radix-tree's protcol
and don't want to account out-of-vm's control pages.

When special_mapping_fault() is called, page->mapping is tend to be NULL 
and it's charged as Anonymous page.
insert_page() also handles some special pages from drivers.

This patch is for avoiding to account special pages.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 mm/memory.c |   18 ++++++------------
 mm/rmap.c   |    4 ++--
 2 files changed, 8 insertions(+), 14 deletions(-)

Index: mmotm-2.6.27-rc6+/mm/memory.c
===================================================================
--- mmotm-2.6.27-rc6+.orig/mm/memory.c
+++ mmotm-2.6.27-rc6+/mm/memory.c
@@ -1323,18 +1323,14 @@ static int insert_page(struct vm_area_st
 	pte_t *pte;
 	spinlock_t *ptl;
 
-	retval = mem_cgroup_charge(page, mm, GFP_KERNEL);
-	if (retval)
-		goto out;
-
 	retval = -EINVAL;
 	if (PageAnon(page))
-		goto out_uncharge;
+		goto out;
 	retval = -ENOMEM;
 	flush_dcache_page(page);
 	pte = get_locked_pte(mm, addr, &ptl);
 	if (!pte)
-		goto out_uncharge;
+		goto out;
 	retval = -EBUSY;
 	if (!pte_none(*pte))
 		goto out_unlock;
@@ -1350,8 +1346,6 @@ static int insert_page(struct vm_area_st
 	return retval;
 out_unlock:
 	pte_unmap_unlock(pte, ptl);
-out_uncharge:
-	mem_cgroup_uncharge_page(page);
 out:
 	return retval;
 }
@@ -2542,7 +2536,7 @@ static int __do_fault(struct mm_struct *
 
 	}
 
-	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
+	if (anon && mem_cgroup_charge(page, mm, GFP_KERNEL)) {
 		ret = VM_FAULT_OOM;
 		goto out;
 	}
@@ -2584,10 +2578,10 @@ static int __do_fault(struct mm_struct *
 		/* no need to invalidate: a not-present page won't be cached */
 		update_mmu_cache(vma, address, entry);
 	} else {
-		mem_cgroup_uncharge_page(page);
-		if (anon)
+		if (anon) {
+			mem_cgroup_uncharge_page(page);
 			page_cache_release(page);
-		else
+		} else
 			anon = 1; /* no anon but release faulted_page */
 	}
 
Index: mmotm-2.6.27-rc6+/mm/rmap.c
===================================================================
--- mmotm-2.6.27-rc6+.orig/mm/rmap.c
+++ mmotm-2.6.27-rc6+/mm/rmap.c
@@ -725,8 +725,8 @@ void page_remove_rmap(struct page *page,
 			page_clear_dirty(page);
 			set_page_dirty(page);
 		}
-
-		mem_cgroup_uncharge_page(page);
+		if (PageAnon(page))
+			mem_cgroup_uncharge_page(page);
 		__dec_zone_page_state(page,
 			PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED);
 		/*

Re: [PATCH 1/12] memcg avoid accounting special mappings not on LRU

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> There are not-on-LRU pages which can be mapped and they are not worth to
> be accounted. (becasue we can't shrink them and need dirty codes to handle
> specical case) We'd like to make use of usual objrmap/radix-tree's protcol
> and don't want to account out-of-vm's control pages.
> 
> When special_mapping_fault() is called, page->mapping is tend to be NULL 
> and it's charged as Anonymous page.
> insert_page() also handles some special pages from drivers.
> 
> This patch is for avoiding to account special pages.
> 

Hmm... I am a little concerned that with these changes actual usage will much
more than what we report in memory.usage_in_bytes. Why not move them to
non-reclaimable LRU list as unevictable pages (once those patches go in, we can
push this as well). I suspect the size of special pages is too short to affect
anything or are you seeing something very different?
-- 
	Balbir

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Re: [PATCH 1/12] memcg avoid accounting special mappings not on LRU

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 13:55:54 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> KAMEZAWA Hiroyuki wrote:
> > There are not-on-LRU pages which can be mapped and they are not worth to
> > be accounted. (becasue we can't shrink them and need dirty codes to handle
> > specical case) We'd like to make use of usual objrmap/radix-tree's protcol
> > and don't want to account out-of-vm's control pages.
> > 
> > When special_mapping_fault() is called, page->mapping is tend to be NULL 
> > and it's charged as Anonymous page.
> > insert_page() also handles some special pages from drivers.
> > 
> > This patch is for avoiding to account special pages.
> > 
> 
> Hmm... I am a little concerned that with these changes actual usage will much
> more than what we report in memory.usage_in_bytes. Why not move them to
> non-reclaimable LRU list as unevictable pages (once those patches go in, we can
> push this as well). 

Because they are not on LRU ...i.e. !PageLRU(page)

> I suspect the size of special pages is too short to affect
> anything or are you seeing something very different?

I don't want put pages never goes to LRU onto memcgroup's LRU.

Thanks,
-Kame

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Re: [PATCH 1/12] memcg avoid accounting special mappings not on LRU

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> On Fri, 26 Sep 2008 13:55:54 +0530
> Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> 
>> KAMEZAWA Hiroyuki wrote:
>>> There are not-on-LRU pages which can be mapped and they are not worth to
>>> be accounted. (becasue we can't shrink them and need dirty codes to handle
>>> specical case) We'd like to make use of usual objrmap/radix-tree's protcol
>>> and don't want to account out-of-vm's control pages.
>>>
>>> When special_mapping_fault() is called, page->mapping is tend to be NULL 
>>> and it's charged as Anonymous page.
>>> insert_page() also handles some special pages from drivers.
>>>
>>> This patch is for avoiding to account special pages.
>>>
>> Hmm... I am a little concerned that with these changes actual usage will much
>> more than what we report in memory.usage_in_bytes. Why not move them to
>> non-reclaimable LRU list as unevictable pages (once those patches go in, we can
>> push this as well). 
> 
> Because they are not on LRU ...i.e. !PageLRU(page)
> 

I understand.. Thanks for clarifying.. my concern is w.r.t accounting, we
account it in RSS (file RSS).

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	Balbir

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Re: [PATCH 1/12] memcg avoid accounting special mappings not on LRU

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 15:02:13 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> KAMEZAWA Hiroyuki wrote:
> > On Fri, 26 Sep 2008 13:55:54 +0530
> > Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> > 
> >> KAMEZAWA Hiroyuki wrote:
> >>> There are not-on-LRU pages which can be mapped and they are not worth to
> >>> be accounted. (becasue we can't shrink them and need dirty codes to handle
> >>> specical case) We'd like to make use of usual objrmap/radix-tree's protcol
> >>> and don't want to account out-of-vm's control pages.
> >>>
> >>> When special_mapping_fault() is called, page->mapping is tend to be NULL 
> >>> and it's charged as Anonymous page.
> >>> insert_page() also handles some special pages from drivers.
> >>>
> >>> This patch is for avoiding to account special pages.
> >>>
> >> Hmm... I am a little concerned that with these changes actual usage will much
> >> more than what we report in memory.usage_in_bytes. Why not move them to
> >> non-reclaimable LRU list as unevictable pages (once those patches go in, we can
> >> push this as well). 
> > 
> > Because they are not on LRU ...i.e. !PageLRU(page)
> > 
> 
> I understand.. Thanks for clarifying.. my concern is w.r.t accounting, we
> account it in RSS (file RSS).
> 
Yes. Because page->mapping is NULL, there are accounted as RSS.

AFAIK, what bad about !PageLRU(page) is..
1. we skips !PageLRU(page) in force_empty. and we cannot reduce account.
2. we don't know we can trust that page is treated as usual LRU page.

I'll update description.

Thanks,
-Kame





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[PATCH 2/12] memcg move charege() call to swapped-in page under lock_page()

[KAMEZAWA Hiroyuki]

While page-cache's charge/uncharge is done under page_lock(), swap-cache
isn't. (anonymous page is charged when it's newly allocated.)

This patch moves do_swap_page()'s charge() call under lock. This helps
us to avoid to charge already mapped one, unnecessary calls.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 mm/memory.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

Index: mmotm-2.6.27-rc7+/mm/memory.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memory.c
+++ mmotm-2.6.27-rc7+/mm/memory.c
@@ -2320,15 +2320,14 @@ static int do_swap_page(struct mm_struct
 		count_vm_event(PGMAJFAULT);
 	}
 
+	lock_page(page);
+	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
+
 	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
-		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
 		ret = VM_FAULT_OOM;
 		goto out;
 	}
-
 	mark_page_accessed(page);
-	lock_page(page);
-	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
 
 	/*
 	 * Back out if somebody else already faulted in this pte.

Re: [PATCH 2/12] memcg move charege() call to swapped-in page under lock_page()

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> While page-cache's charge/uncharge is done under page_lock(), swap-cache
> isn't. (anonymous page is charged when it's newly allocated.)
> 
> This patch moves do_swap_page()'s charge() call under lock. This helps
> us to avoid to charge already mapped one, unnecessary calls.
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

Seems reasonable to me

Just one quick comment though, as a result of this change, mark_page_accessed is
now called with PageLock held, I suspect you would want to move that call prior
to lock_page().



-- 
	Balbir

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Re: [PATCH 2/12] memcg move charege() call to swapped-in page under lock_page()

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 14:06:02 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> KAMEZAWA Hiroyuki wrote:
> > While page-cache's charge/uncharge is done under page_lock(), swap-cache
> > isn't. (anonymous page is charged when it's newly allocated.)
> > 
> > This patch moves do_swap_page()'s charge() call under lock. This helps
> > us to avoid to charge already mapped one, unnecessary calls.
> > 
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
> Seems reasonable to me
> 
> Just one quick comment though, as a result of this change, mark_page_accessed is
> now called with PageLock held, I suspect you would want to move that call prior
> to lock_page().
> 
Ok. I'll check it

Thanks,
-Kame
> 
> 
> -- 
> 	Balbir
> 

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[PATCH 3/12] memcg make root cgroup unlimited.

[KAMEZAWA Hiroyuki]

Make root cgroup of memory resource controller to have no limit.

By this, users cannot set limit to root group. This is for making root cgroup
as a kind of trash-can.

For accounting pages which has no owner, which are created by force_empty,
we need some cgroup with no_limit. A patch for rewriting force_empty will
will follow this one.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 Documentation/controllers/memory.txt |    4 ++++
 mm/memcontrol.c                      |    7 +++++++
 2 files changed, 11 insertions(+)

Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -136,6 +136,9 @@ struct mem_cgroup {
 };
 static struct mem_cgroup init_mem_cgroup;
 
+#define is_root_cgroup(cgrp)	((cgrp) == &init_mem_cgroup)
+
+
 /*
  * We use the lower bit of the page->page_cgroup pointer as a bit spin
  * lock.  We need to ensure that page->page_cgroup is at least two
@@ -945,6 +948,10 @@ static int mem_cgroup_write(struct cgrou
 
 	switch (cft->private) {
 	case RES_LIMIT:
+		if (is_root_cgroup(memcg)) {
+			ret = -EINVAL;
+			break;
+		}
 		/* This function does all necessary parse...reuse it */
 		ret = res_counter_memparse_write_strategy(buffer, &val);
 		if (!ret)
Index: mmotm-2.6.27-rc7+/Documentation/controllers/memory.txt
===================================================================
--- mmotm-2.6.27-rc7+.orig/Documentation/controllers/memory.txt
+++ mmotm-2.6.27-rc7+/Documentation/controllers/memory.txt
@@ -121,6 +121,9 @@ The corresponding routines that remove a
 a page from Page Cache is used to decrement the accounting counters of the
 cgroup.
 
+The root cgroup is not allowed to be set limit but usage is accounted.
+For controlling usage of memory, you need to create a cgroup.
+
 2.3 Shared Page Accounting
 
 Shared pages are accounted on the basis of the first touch approach. The
@@ -172,6 +175,7 @@ We can alter the memory limit:
 
 NOTE: We can use a suffix (k, K, m, M, g or G) to indicate values in kilo,
 mega or gigabytes.
+Note: root cgroup is not able to be set limit.
 
 # cat /cgroups/0/memory.limit_in_bytes
 4194304

Re: [PATCH 3/12] memcg make root cgroup unlimited.

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> Make root cgroup of memory resource controller to have no limit.
> 
> By this, users cannot set limit to root group. This is for making root cgroup
> as a kind of trash-can.
> 
> For accounting pages which has no owner, which are created by force_empty,
> we need some cgroup with no_limit. A patch for rewriting force_empty will
> will follow this one.
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

This is an ABI change (although not too many people might be using it, I wonder
if we should add memory.features (a set of flags and let users enable them and
provide good defaults), like sched features.

-- 
	Balbir

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Re: [PATCH 3/12] memcg make root cgroup unlimited.

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 14:11:00 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> KAMEZAWA Hiroyuki wrote:
> > Make root cgroup of memory resource controller to have no limit.
> > 
> > By this, users cannot set limit to root group. This is for making root cgroup
> > as a kind of trash-can.
> > 
> > For accounting pages which has no owner, which are created by force_empty,
> > we need some cgroup with no_limit. A patch for rewriting force_empty will
> > will follow this one.
> > 
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
> This is an ABI change (although not too many people might be using it, I wonder
> if we should add memory.features (a set of flags and let users enable them and
> provide good defaults), like sched features.
> 
I think "feature" flag is complicated, at this stage.
We'll add more features and not settled yet.

Hmm, if you don't like this,
calling try_to_free_page() at force_empty() instead of move_account() ?


Thanks,
-Kame

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Re: [PATCH 3/12] memcg make root cgroup unlimited.

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> On Fri, 26 Sep 2008 14:11:00 +0530
> Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> 
>> KAMEZAWA Hiroyuki wrote:
>>> Make root cgroup of memory resource controller to have no limit.
>>>
>>> By this, users cannot set limit to root group. This is for making root cgroup
>>> as a kind of trash-can.
>>>
>>> For accounting pages which has no owner, which are created by force_empty,
>>> we need some cgroup with no_limit. A patch for rewriting force_empty will
>>> will follow this one.
>>>
>>> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>> This is an ABI change (although not too many people might be using it, I wonder
>> if we should add memory.features (a set of flags and let users enable them and
>> provide good defaults), like sched features.
>>
> I think "feature" flag is complicated, at this stage.
> We'll add more features and not settled yet.
> 

I know.. but breaking ABI is a bad bad thing. We'll have to keep the feature
flags extensible (add new things). If we all feel we don't have enough users
affected by this change, I might agree with you and make that change.

> Hmm, if you don't like this,
> calling try_to_free_page() at force_empty() instead of move_account() ?
> 

Not sure I understand this.


-- 
	Balbir

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Re: [PATCH 3/12] memcg make root cgroup unlimited.

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 14:59:48 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> > I think "feature" flag is complicated, at this stage.
> > We'll add more features and not settled yet.
> > 
> 
> I know.. but breaking ABI is a bad bad thing. We'll have to keep the feature
> flags extensible (add new things). If we all feel we don't have enough users
> affected by this change, I might agree with you and make that change.
> 
Hmm...I'll drop this and add force_empty_may_fail logic in changes in force_empty.

> > Hmm, if you don't like this,
> > calling try_to_free_page() at force_empty() instead of move_account() ?
> > 
> 
> Not sure I understand this.
> 
In following series, force_empty() uses move_account() rather than forget all.
By this, accounted file caches are kept as accounted and the whole accounting
will be sane.

Another choice is calling try_to_free_pages() at force_empty rather than forget all
and makes memory usage to be Zero. This will also makes the whole accounting sange.

Thanks,
-Kame

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[PATCH 4/12] memcg make page->mapping NULL before calling uncharge

[KAMEZAWA Hiroyuki]

This patch tries to make page->mapping to be NULL before
mem_cgroup_uncharge_cache_page() is called.

"page->mapping == NULL" is a good check for "whether the page is still
radix-tree or not".
This patch also adds BUG_ON() to mem_cgroup_uncharge_cache_page();


Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 mm/filemap.c    |    2 +-
 mm/memcontrol.c |    1 +
 mm/migrate.c    |   12 +++++++++---
 3 files changed, 11 insertions(+), 4 deletions(-)

Index: mmotm-2.6.27-rc7+/mm/filemap.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/filemap.c
+++ mmotm-2.6.27-rc7+/mm/filemap.c
@@ -116,12 +116,12 @@ void __remove_from_page_cache(struct pag
 {
 	struct address_space *mapping = page->mapping;
 
-	mem_cgroup_uncharge_cache_page(page);
 	radix_tree_delete(&mapping->page_tree, page->index);
 	page->mapping = NULL;
 	mapping->nrpages--;
 	__dec_zone_page_state(page, NR_FILE_PAGES);
 	BUG_ON(page_mapped(page));
+	mem_cgroup_uncharge_cache_page(page);
 
 	/*
 	 * Some filesystems seem to re-dirty the page even after
Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -737,6 +737,7 @@ void mem_cgroup_uncharge_page(struct pag
 void mem_cgroup_uncharge_cache_page(struct page *page)
 {
 	VM_BUG_ON(page_mapped(page));
+	VM_BUG_ON(page->mapping);
 	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);
 }
 
Index: mmotm-2.6.27-rc7+/mm/migrate.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/migrate.c
+++ mmotm-2.6.27-rc7+/mm/migrate.c
@@ -330,8 +330,6 @@ static int migrate_page_move_mapping(str
 	__inc_zone_page_state(newpage, NR_FILE_PAGES);
 
 	spin_unlock_irq(&mapping->tree_lock);
-	if (!PageSwapCache(newpage))
-		mem_cgroup_uncharge_cache_page(page);
 
 	return 0;
 }
@@ -378,7 +376,15 @@ static void migrate_page_copy(struct pag
 #endif
 	ClearPagePrivate(page);
 	set_page_private(page, 0);
-	page->mapping = NULL;
+	/* page->mapping contains a flag for PageAnon() */
+	if (PageAnon(page)) {
+		/* This page is uncharged at try_to_unmap(). */
+		page->mapping = NULL;
+	} else {
+		/* Obsolete file cache should be uncharged */
+		page->mapping = NULL;
+		mem_cgroup_uncharge_cache_page(page);
+	}
 
 	/*
 	 * If any waiters have accumulated on the new page then

Re: [PATCH 4/12] memcg make page->mapping NULL before calling uncharge

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> This patch tries to make page->mapping to be NULL before
> mem_cgroup_uncharge_cache_page() is called.
> 
> "page->mapping == NULL" is a good check for "whether the page is still
> radix-tree or not".
> This patch also adds BUG_ON() to mem_cgroup_uncharge_cache_page();
> 
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

Looks good, small nit-pick below

>  #endif
>  	ClearPagePrivate(page);
>  	set_page_private(page, 0);
> -	page->mapping = NULL;
> +	/* page->mapping contains a flag for PageAnon() */
> +	if (PageAnon(page)) {
> +		/* This page is uncharged at try_to_unmap(). */
> +		page->mapping = NULL;
> +	} else {
> +		/* Obsolete file cache should be uncharged */
> +		page->mapping = NULL;
> +		mem_cgroup_uncharge_cache_page(page);
> +	}
> 

Isn't it better and correct coding style to do

	/*
	 * Uncharge obsolete file cache
	 */
	if (!PageAnon(page))
		mem_cgroup_uncharge_cache_page(page);
	/* else - uncharged at try_to_unmap() */
	page->mapping = NULL;


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	Balbir

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Re: [PATCH 4/12] memcg make page->mapping NULL before calling uncharge

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 15:17:48 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> KAMEZAWA Hiroyuki wrote:
> > This patch tries to make page->mapping to be NULL before
> > mem_cgroup_uncharge_cache_page() is called.
> > 
> > "page->mapping == NULL" is a good check for "whether the page is still
> > radix-tree or not".
> > This patch also adds BUG_ON() to mem_cgroup_uncharge_cache_page();
> > 
> > 
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
> Looks good, small nit-pick below
> 
> >  #endif
> >  	ClearPagePrivate(page);
> >  	set_page_private(page, 0);
> > -	page->mapping = NULL;
> > +	/* page->mapping contains a flag for PageAnon() */
> > +	if (PageAnon(page)) {
> > +		/* This page is uncharged at try_to_unmap(). */
> > +		page->mapping = NULL;
> > +	} else {
> > +		/* Obsolete file cache should be uncharged */
> > +		page->mapping = NULL;
> > +		mem_cgroup_uncharge_cache_page(page);
> > +	}
> > 
> 
> Isn't it better and correct coding style to do
> 
> 	/*
> 	 * Uncharge obsolete file cache
> 	 */
> 	if (!PageAnon(page))
> 		mem_cgroup_uncharge_cache_page(page);
> 	/* else - uncharged at try_to_unmap() */
> 	page->mapping = NULL;
> 
yea, maybe.
I always wonder what I should do when I want to add comment to if-then-else...

But ok, will remove {}.

Thanks,
-Kame



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[PATCH 5/12] memcg make page_cgroup->flags atomic

[KAMEZAWA Hiroyuki]

This patch makes page_cgroup->flags to be atomic_ops and define
functions (and macros) to access it.

This patch itself makes memcg slow but this patch's final purpose is 
to remove lock_page_cgroup() and allowing fast access to page_cgroup.
(And total performance will increase after all patches applied.)

Before trying to modify memory resource controller, this atomic operation
on flags is necessary. Most of flags in this patch is for LRU and modfied
under mz->lru_lock but we'll add another flags which is not for LRU soon.
So we use atomic version here.

 
Changelog: (v4) -> (v5)
 - removed unsued operations.
 - adjusted to new ctype MEM_CGROUP_CHARGE_TYPE_SHMEM

Changelog: (v3) -> (v4)
 - no changes.

Changelog:  (v2) -> (v3)
 - renamed macros and flags to be longer name.
 - added comments.
 - added "default bit set" for File, Shmem, Anon.

Changelog:  (preview) -> (v1):
 - patch ordering is changed.
 - Added macro for defining functions for Test/Set/Clear bit.
 - made the names of flags shorter.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 mm/memcontrol.c |  122 +++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 82 insertions(+), 40 deletions(-)

Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -161,12 +161,46 @@ struct page_cgroup {
 	struct list_head lru;		/* per cgroup LRU list */
 	struct page *page;
 	struct mem_cgroup *mem_cgroup;
-	int flags;
+	unsigned long flags;
 };
-#define PAGE_CGROUP_FLAG_CACHE	   (0x1)	/* charged as cache */
-#define PAGE_CGROUP_FLAG_ACTIVE    (0x2)	/* page is active in this cgroup */
-#define PAGE_CGROUP_FLAG_FILE	   (0x4)	/* page is file system backed */
-#define PAGE_CGROUP_FLAG_UNEVICTABLE (0x8)	/* page is unevictableable */
+
+enum {
+	/* flags for mem_cgroup */
+	PCG_CACHE, /* charged as cache */
+	/* flags for LRU placement */
+	PCG_ACTIVE, /* page is active in this cgroup */
+	PCG_FILE, /* page is file system backed */
+	PCG_UNEVICTABLE, /* page is unevictableable */
+};
+
+#define TESTPCGFLAG(uname, lname)			\
+static inline int PageCgroup##uname(struct page_cgroup *pc)	\
+	{ return test_bit(PCG_##lname, &pc->flags); }
+
+#define SETPCGFLAG(uname, lname)			\
+static inline void SetPageCgroup##uname(struct page_cgroup *pc)\
+	{ set_bit(PCG_##lname, &pc->flags);  }
+
+#define CLEARPCGFLAG(uname, lname)			\
+static inline void ClearPageCgroup##uname(struct page_cgroup *pc)	\
+	{ clear_bit(PCG_##lname, &pc->flags);  }
+
+
+/* Cache flag is set only once (at allocation) */
+TESTPCGFLAG(Cache, CACHE)
+
+/* LRU management flags (from global-lru definition) */
+TESTPCGFLAG(File, FILE)
+SETPCGFLAG(File, FILE)
+CLEARPCGFLAG(File, FILE)
+
+TESTPCGFLAG(Active, ACTIVE)
+SETPCGFLAG(Active, ACTIVE)
+CLEARPCGFLAG(Active, ACTIVE)
+
+TESTPCGFLAG(Unevictable, UNEVICTABLE)
+SETPCGFLAG(Unevictable, UNEVICTABLE)
+CLEARPCGFLAG(Unevictable, UNEVICTABLE)
 
 static int page_cgroup_nid(struct page_cgroup *pc)
 {
@@ -181,21 +215,31 @@ static enum zone_type page_cgroup_zid(st
 enum charge_type {
 	MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
 	MEM_CGROUP_CHARGE_TYPE_MAPPED,
-	MEM_CGROUP_CHARGE_TYPE_FORCE,	/* used by force_empty */
 	MEM_CGROUP_CHARGE_TYPE_SHMEM,	/* used by page migration of shmem */
+	MEM_CGROUP_CHARGE_TYPE_FORCE,	/* used by force_empty */
+	NR_CHARGE_TYPE,
+};
+
+static const unsigned long
+pcg_default_flags[NR_CHARGE_TYPE] = {
+	((1 << PCG_CACHE) | (1 << PCG_FILE)),
+	((1 << PCG_ACTIVE)),
+	((1 << PCG_ACTIVE) | (1 << PCG_CACHE)),
+	0,
 };
 
 /*
  * Always modified under lru lock. Then, not necessary to preempt_disable()
  */
-static void mem_cgroup_charge_statistics(struct mem_cgroup *mem, int flags,
-					bool charge)
+static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
+					 struct page_cgroup *pc,
+					 bool charge)
 {
 	int val = (charge)? 1 : -1;
 	struct mem_cgroup_stat *stat = &mem->stat;
 
 	VM_BUG_ON(!irqs_disabled());
-	if (flags & PAGE_CGROUP_FLAG_CACHE)
+	if (PageCgroupCache(pc))
 		__mem_cgroup_stat_add_safe(stat, MEM_CGROUP_STAT_CACHE, val);
 	else
 		__mem_cgroup_stat_add_safe(stat, MEM_CGROUP_STAT_RSS, val);
@@ -296,18 +340,18 @@ static void __mem_cgroup_remove_list(str
 {
 	int lru = LRU_BASE;
 
-	if (pc->flags & PAGE_CGROUP_FLAG_UNEVICTABLE)
+	if (PageCgroupUnevictable(pc))
 		lru = LRU_UNEVICTABLE;
 	else {
-		if (pc->flags & PAGE_CGROUP_FLAG_ACTIVE)
+		if (PageCgroupActive(pc))
 			lru += LRU_ACTIVE;
-		if (pc->flags & PAGE_CGROUP_FLAG_FILE)
+		if (PageCgroupFile(pc))
 			lru += LRU_FILE;
 	}
 
 	MEM_CGROUP_ZSTAT(mz, lru) -= 1;
 
-	mem_cgroup_charge_statistics(pc->mem_cgroup, pc->flags, false);
+	mem_cgroup_charge_statistics(pc->mem_cgroup, pc, false);
 	list_del(&pc->lru);
 }
 
@@ -316,27 +360,27 @@ static void __mem_cgroup_add_list(struct
 {
 	int lru = LRU_BASE;
 
-	if (pc->flags & PAGE_CGROUP_FLAG_UNEVICTABLE)
+	if (PageCgroupUnevictable(pc))
 		lru = LRU_UNEVICTABLE;
 	else {
-		if (pc->flags & PAGE_CGROUP_FLAG_ACTIVE)
+		if (PageCgroupActive(pc))
 			lru += LRU_ACTIVE;
-		if (pc->flags & PAGE_CGROUP_FLAG_FILE)
+		if (PageCgroupFile(pc))
 			lru += LRU_FILE;
 	}
 
 	MEM_CGROUP_ZSTAT(mz, lru) += 1;
 	list_add(&pc->lru, &mz->lists[lru]);
 
-	mem_cgroup_charge_statistics(pc->mem_cgroup, pc->flags, true);
+	mem_cgroup_charge_statistics(pc->mem_cgroup, pc, true);
 }
 
 static void __mem_cgroup_move_lists(struct page_cgroup *pc, enum lru_list lru)
 {
 	struct mem_cgroup_per_zone *mz = page_cgroup_zoneinfo(pc);
-	int active    = pc->flags & PAGE_CGROUP_FLAG_ACTIVE;
-	int file      = pc->flags & PAGE_CGROUP_FLAG_FILE;
-	int unevictable = pc->flags & PAGE_CGROUP_FLAG_UNEVICTABLE;
+	int active    = PageCgroupActive(pc);
+	int file      = PageCgroupFile(pc);
+	int unevictable = PageCgroupUnevictable(pc);
 	enum lru_list from = unevictable ? LRU_UNEVICTABLE :
 				(LRU_FILE * !!file + !!active);
 
@@ -344,16 +388,20 @@ static void __mem_cgroup_move_lists(stru
 		return;
 
 	MEM_CGROUP_ZSTAT(mz, from) -= 1;
-
+	/*
+	 * However this is done under mz->lru_lock, another flags, which
+	 * are not related to LRU, will be modified from out-of-lock.
+	 * We have to use atomic set/clear flags.
+	 */
 	if (is_unevictable_lru(lru)) {
-		pc->flags &= ~PAGE_CGROUP_FLAG_ACTIVE;
-		pc->flags |= PAGE_CGROUP_FLAG_UNEVICTABLE;
+		ClearPageCgroupActive(pc);
+		SetPageCgroupUnevictable(pc);
 	} else {
 		if (is_active_lru(lru))
-			pc->flags |= PAGE_CGROUP_FLAG_ACTIVE;
+			SetPageCgroupActive(pc);
 		else
-			pc->flags &= ~PAGE_CGROUP_FLAG_ACTIVE;
-		pc->flags &= ~PAGE_CGROUP_FLAG_UNEVICTABLE;
+			ClearPageCgroupActive(pc);
+		ClearPageCgroupUnevictable(pc);
 	}
 
 	MEM_CGROUP_ZSTAT(mz, lru) += 1;
@@ -590,16 +638,7 @@ static int mem_cgroup_charge_common(stru
 	 * If a page is accounted as a page cache, insert to inactive list.
 	 * If anon, insert to active list.
 	 */
-	if (ctype == MEM_CGROUP_CHARGE_TYPE_CACHE) {
-		pc->flags = PAGE_CGROUP_FLAG_CACHE;
-		if (page_is_file_cache(page))
-			pc->flags |= PAGE_CGROUP_FLAG_FILE;
-		else
-			pc->flags |= PAGE_CGROUP_FLAG_ACTIVE;
-	} else if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
-		pc->flags = PAGE_CGROUP_FLAG_ACTIVE;
-	else /* MEM_CGROUP_CHARGE_TYPE_SHMEM */
-		pc->flags = PAGE_CGROUP_FLAG_CACHE | PAGE_CGROUP_FLAG_ACTIVE;
+	pc->flags = pcg_default_flags[ctype];
 
 	lock_page_cgroup(page);
 	if (unlikely(page_get_page_cgroup(page))) {
@@ -678,8 +717,12 @@ int mem_cgroup_cache_charge(struct page 
 	if (unlikely(!mm))
 		mm = &init_mm;
 
-	return mem_cgroup_charge_common(page, mm, gfp_mask,
+	if (page_is_file_cache(page))
+		return mem_cgroup_charge_common(page, mm, gfp_mask,
 				MEM_CGROUP_CHARGE_TYPE_CACHE, NULL);
+	else
+		return mem_cgroup_charge_common(page, mm, gfp_mask,
+				MEM_CGROUP_CHARGE_TYPE_SHMEM, NULL);
 }
 
 /*
@@ -707,8 +750,7 @@ __mem_cgroup_uncharge_common(struct page
 	VM_BUG_ON(pc->page != page);
 
 	if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
-	    && ((pc->flags & PAGE_CGROUP_FLAG_CACHE)
-		|| page_mapped(page)))
+	    && ((PageCgroupCache(pc) || page_mapped(page))))
 		goto unlock;
 
 	mz = page_cgroup_zoneinfo(pc);
@@ -759,7 +801,7 @@ int mem_cgroup_prepare_migration(struct 
 	if (pc) {
 		mem = pc->mem_cgroup;
 		css_get(&mem->css);
-		if (pc->flags & PAGE_CGROUP_FLAG_CACHE) {
+		if (PageCgroupCache(pc)) {
 			if (page_is_file_cache(page))
 				ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
 			else

Re: [PATCH 5/12] memcg make page_cgroup->flags atomic

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> This patch makes page_cgroup->flags to be atomic_ops and define
> functions (and macros) to access it.
> 
> This patch itself makes memcg slow but this patch's final purpose is 
> to remove lock_page_cgroup() and allowing fast access to page_cgroup.
> (And total performance will increase after all patches applied.)
> 

Looks good to me

Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
provided we push in the lockless ones too :)

-- 
	Balbir

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[PATCH 6/12] memcg optimize percpu stat

[KAMEZAWA Hiroyuki]

Some obvious optimization to memcg.

I found mem_cgroup_charge_statistics() is a little big (in object) and
does unnecessary address calclation.
This patch is for optimization to reduce the size of this function.

And res_counter_charge() is 'likely' to success.

Changelog v3->v4:
 - merged with an other leaf patch.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 mm/memcontrol.c |   18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -66,11 +66,10 @@ struct mem_cgroup_stat {
 /*
  * For accounting under irq disable, no need for increment preempt count.
  */
-static void __mem_cgroup_stat_add_safe(struct mem_cgroup_stat *stat,
+static inline void __mem_cgroup_stat_add_safe(struct mem_cgroup_stat_cpu *stat,
 		enum mem_cgroup_stat_index idx, int val)
 {
-	int cpu = smp_processor_id();
-	stat->cpustat[cpu].count[idx] += val;
+	stat->count[idx] += val;
 }
 
 static s64 mem_cgroup_read_stat(struct mem_cgroup_stat *stat,
@@ -237,18 +236,21 @@ static void mem_cgroup_charge_statistics
 {
 	int val = (charge)? 1 : -1;
 	struct mem_cgroup_stat *stat = &mem->stat;
+	struct mem_cgroup_stat_cpu *cpustat;
 
 	VM_BUG_ON(!irqs_disabled());
+
+	cpustat = &stat->cpustat[smp_processor_id()];
 	if (PageCgroupCache(pc))
-		__mem_cgroup_stat_add_safe(stat, MEM_CGROUP_STAT_CACHE, val);
+		__mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_CACHE, val);
 	else
-		__mem_cgroup_stat_add_safe(stat, MEM_CGROUP_STAT_RSS, val);
+		__mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_RSS, val);
 
 	if (charge)
-		__mem_cgroup_stat_add_safe(stat,
+		__mem_cgroup_stat_add_safe(cpustat,
 				MEM_CGROUP_STAT_PGPGIN_COUNT, 1);
 	else
-		__mem_cgroup_stat_add_safe(stat,
+		__mem_cgroup_stat_add_safe(cpustat,
 				MEM_CGROUP_STAT_PGPGOUT_COUNT, 1);
 }
 
@@ -609,7 +611,7 @@ static int mem_cgroup_charge_common(stru
 		css_get(&memcg->css);
 	}
 
-	while (res_counter_charge(&mem->res, PAGE_SIZE)) {
+	while (unlikely(res_counter_charge(&mem->res, PAGE_SIZE))) {
 		if (!(gfp_mask & __GFP_WAIT))
 			goto out;
 

Re: [PATCH 6/12] memcg optimize percpu stat

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> Some obvious optimization to memcg.
> 
> I found mem_cgroup_charge_statistics() is a little big (in object) and
> does unnecessary address calclation.
> This patch is for optimization to reduce the size of this function.
> 
> And res_counter_charge() is 'likely' to success.
> 
> Changelog v3->v4:
>  - merged with an other leaf patch.
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
>  mm/memcontrol.c |   18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
> 
> Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
> ===================================================================
> --- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
> +++ mmotm-2.6.27-rc7+/mm/memcontrol.c
> @@ -66,11 +66,10 @@ struct mem_cgroup_stat {
>  /*
>   * For accounting under irq disable, no need for increment preempt count.
>   */
> -static void __mem_cgroup_stat_add_safe(struct mem_cgroup_stat *stat,
> +static inline void __mem_cgroup_stat_add_safe(struct mem_cgroup_stat_cpu *stat,
>  		enum mem_cgroup_stat_index idx, int val)
>  {
> -	int cpu = smp_processor_id();
> -	stat->cpustat[cpu].count[idx] += val;
> +	stat->count[idx] += val;
>  }
> 
>  static s64 mem_cgroup_read_stat(struct mem_cgroup_stat *stat,
> @@ -237,18 +236,21 @@ static void mem_cgroup_charge_statistics
>  {
>  	int val = (charge)? 1 : -1;
>  	struct mem_cgroup_stat *stat = &mem->stat;
> +	struct mem_cgroup_stat_cpu *cpustat;
> 
>  	VM_BUG_ON(!irqs_disabled());
> +
> +	cpustat = &stat->cpustat[smp_processor_id()];
>  	if (PageCgroupCache(pc))
> -		__mem_cgroup_stat_add_safe(stat, MEM_CGROUP_STAT_CACHE, val);
> +		__mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_CACHE, val);
>  	else
> -		__mem_cgroup_stat_add_safe(stat, MEM_CGROUP_STAT_RSS, val);
> +		__mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_RSS, val);
> 
>  	if (charge)
> -		__mem_cgroup_stat_add_safe(stat,
> +		__mem_cgroup_stat_add_safe(cpustat,
>  				MEM_CGROUP_STAT_PGPGIN_COUNT, 1);
>  	else
> -		__mem_cgroup_stat_add_safe(stat,
> +		__mem_cgroup_stat_add_safe(cpustat,
>  				MEM_CGROUP_STAT_PGPGOUT_COUNT, 1);
>  }
> 
> @@ -609,7 +611,7 @@ static int mem_cgroup_charge_common(stru
>  		css_get(&memcg->css);
>  	}
> 
> -	while (res_counter_charge(&mem->res, PAGE_SIZE)) {
> +	while (unlikely(res_counter_charge(&mem->res, PAGE_SIZE))) {
>  		if (!(gfp_mask & __GFP_WAIT))
>  			goto out;
> 
> 

Looks good to me

Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>

-- 
	Balbir

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[PATCH 7/12] memcg add function to move account

[KAMEZAWA Hiroyuki]

This patch provides a function to move account information of a page between
mem_cgroups.

This moving of page_cgroup is done under
 - lru_lock of source/destination mem_cgroup is held.
 - lock_page_cgroup() is held.

Then, a routine which touches pc->mem_cgroup without lock_page_cgroup() should
confirm pc->mem_cgroup is still valid or not. Typlical code can be following.

(while page is not under lock_page())
	mem = pc->mem_cgroup;
	mz = page_cgroup_zoneinfo(pc)
	spin_lock_irqsave(&mz->lru_lock);
	if (pc->mem_cgroup == mem)
		...../* some list handling */
	spin_unlock_irq(&mz->lru_lock);

Or better way is
	lock_page_cgroup(pc);
	....
	unlock_page_cgroup(pc);

But you should confirm the nest of lock and avoid deadlock.
(trylock is better if it's ok.)

If you find page_cgroup from mem_cgroup's LRU under mz->lru_lock,
you don't have to worry about what pc->mem_cgroup points to.

Changelog: (v4) -> (v5)
  - check for lock_page() is removed.
  - rewrote description.

Changelog: (v2) -> (v4)
  - added lock_page_cgroup().
  - splitted out from new-force-empty patch.
  - added how-to-use text.
  - fixed race in __mem_cgroup_uncharge_common().

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 mm/memcontrol.c |   84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 81 insertions(+), 3 deletions(-)

Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -426,6 +426,7 @@ int task_in_mem_cgroup(struct task_struc
 void mem_cgroup_move_lists(struct page *page, enum lru_list lru)
 {
 	struct page_cgroup *pc;
+	struct mem_cgroup *mem;
 	struct mem_cgroup_per_zone *mz;
 	unsigned long flags;
 
@@ -444,9 +445,14 @@ void mem_cgroup_move_lists(struct page *
 
 	pc = page_get_page_cgroup(page);
 	if (pc) {
+		mem = pc->mem_cgroup;
 		mz = page_cgroup_zoneinfo(pc);
 		spin_lock_irqsave(&mz->lru_lock, flags);
-		__mem_cgroup_move_lists(pc, lru);
+		/*
+		 * check against the race with move_account.
+		 */
+		if (likely(mem == pc->mem_cgroup))
+			__mem_cgroup_move_lists(pc, lru);
 		spin_unlock_irqrestore(&mz->lru_lock, flags);
 	}
 	unlock_page_cgroup(page);
@@ -567,6 +573,70 @@ unsigned long mem_cgroup_isolate_pages(u
 	return nr_taken;
 }
 
+/**
+ * mem_cgroup_move_account - move account of the page
+ * @page ... the target page of being moved.
+ * @pc   ... page_cgroup of the page.
+ * @from ... mem_cgroup which the page is moved from.
+ * @to   ... mem_cgroup which the page is moved to.
+ *
+ * The caller must confirm following.
+ * 1. disable irq.
+ * 2. lru_lock of old mem_cgroup should be held.
+ * 3. pc is guaranteed to be valid and on mem_cgroup's LRU.
+ *
+ * Because we cannot call try_to_free_page() here, the caller must guarantee
+ * this moving of charge never fails. (if charge fails, this call fails.)
+ * Currently this is called only against root cgroup.
+ * which has no limitation of resource.
+ * Returns 0 at success, returns 1 at failure.
+ */
+int mem_cgroup_move_account(struct page *page, struct page_cgroup *pc,
+	struct mem_cgroup *from, struct mem_cgroup *to)
+{
+	struct mem_cgroup_per_zone *from_mz, *to_mz;
+	int nid, zid;
+	int ret = 1;
+
+	VM_BUG_ON(!irqs_disabled());
+
+	nid = page_to_nid(page);
+	zid = page_zonenum(page);
+	from_mz =  mem_cgroup_zoneinfo(from, nid, zid);
+	to_mz =  mem_cgroup_zoneinfo(to, nid, zid);
+
+	if (res_counter_charge(&to->res, PAGE_SIZE)) {
+		/* Now, we assume no_limit...no failure here. */
+		return ret;
+	}
+	if (!try_lock_page_cgroup(page)) {
+		res_counter_uncharge(&to->res, PAGE_SIZE);
+		return ret;
+	}
+
+	if (page_get_page_cgroup(page) != pc) {
+		res_counter_uncharge(&to->res, PAGE_SIZE);
+		goto out;
+	}
+
+	if (spin_trylock(&to_mz->lru_lock)) {
+		__mem_cgroup_remove_list(from_mz, pc);
+		css_put(&from->css);
+		res_counter_uncharge(&from->res, PAGE_SIZE);
+		pc->mem_cgroup = to;
+		css_get(&to->css);
+		__mem_cgroup_add_list(to_mz, pc);
+		ret = 0;
+		spin_unlock(&to_mz->lru_lock);
+	} else {
+		res_counter_uncharge(&to->res, PAGE_SIZE);
+	}
+out:
+	unlock_page_cgroup(page);
+
+	return ret;
+}
+
 /*
  * Charge the memory controller for page usage.
  * Return
@@ -754,16 +824,24 @@ __mem_cgroup_uncharge_common(struct page
 	if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
 	    && ((PageCgroupCache(pc) || page_mapped(page))))
 		goto unlock;
-
+retry:
+	mem = pc->mem_cgroup;
 	mz = page_cgroup_zoneinfo(pc);
 	spin_lock_irqsave(&mz->lru_lock, flags);
+	if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED &&
+	    unlikely(mem != pc->mem_cgroup)) {
+		/* MAPPED account can be done without lock_page().
+		   Check race with mem_cgroup_move_account() */
+		spin_unlock_irqrestore(&mz->lru_lock, flags);
+		goto retry;
+	}
 	__mem_cgroup_remove_list(mz, pc);
 	spin_unlock_irqrestore(&mz->lru_lock, flags);
 
 	page_assign_page_cgroup(page, NULL);
 	unlock_page_cgroup(page);
 
-	mem = pc->mem_cgroup;
+
 	res_counter_uncharge(&mem->res, PAGE_SIZE);
 	css_put(&mem->css);
 

Re: [PATCH 7/12] memcg add function to move account

[Daisuke Nishimura]

> @@ -444,9 +445,14 @@ void mem_cgroup_move_lists(struct page *
>  
>  	pc = page_get_page_cgroup(page);
>  	if (pc) {
> +		mem = pc->mem_cgroup;
>  		mz = page_cgroup_zoneinfo(pc);
>  		spin_lock_irqsave(&mz->lru_lock, flags);
> -		__mem_cgroup_move_lists(pc, lru);
> +		/*
> +		 * check against the race with move_account.
> +		 */
> +		if (likely(mem == pc->mem_cgroup))
> +			__mem_cgroup_move_lists(pc, lru);

(snip)

> @@ -754,16 +824,24 @@ __mem_cgroup_uncharge_common(struct page
>  	if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
>  	    && ((PageCgroupCache(pc) || page_mapped(page))))
>  		goto unlock;
> -
> +retry:
> +	mem = pc->mem_cgroup;
>  	mz = page_cgroup_zoneinfo(pc);
>  	spin_lock_irqsave(&mz->lru_lock, flags);
> +	if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED &&
> +	    unlikely(mem != pc->mem_cgroup)) {
> +		/* MAPPED account can be done without lock_page().
> +		   Check race with mem_cgroup_move_account() */
> +		spin_unlock_irqrestore(&mz->lru_lock, flags);
> +		goto retry;
> +	}

I'm sorry, but I've not been convinced yet why these checks are needed here.
(Those checks are removed by [9/12] anyway.)

IIUC, pc->mem_cgroup is moved to another group only by mem_cgroup_move_account
under lock_page_cgroup( and mz->lru_lock).
And those two above(mem_cgroup_move_lists and __mem_cgroup_uncharge_common) sets
mem = pc->mem_cgroup under lock_page_cgroup, so I don't think those checks
(mem != pc->mem_cgroup) is needed.


Thanks,
Daisuke Nishimura.

> +/**
> + * mem_cgroup_move_account - move account of the page
> + * @page ... the target page of being moved.
> + * @pc   ... page_cgroup of the page.
> + * @from ... mem_cgroup which the page is moved from.
> + * @to   ... mem_cgroup which the page is moved to.
> + *
> + * The caller must confirm following.
> + * 1. disable irq.
> + * 2. lru_lock of old mem_cgroup should be held.
> + * 3. pc is guaranteed to be valid and on mem_cgroup's LRU.
> + *
> + * Because we cannot call try_to_free_page() here, the caller must guarantee
> + * this moving of charge never fails. (if charge fails, this call fails.)
> + * Currently this is called only against root cgroup.
> + * which has no limitation of resource.
> + * Returns 0 at success, returns 1 at failure.
> + */
> +int mem_cgroup_move_account(struct page *page, struct page_cgroup *pc,
> +	struct mem_cgroup *from, struct mem_cgroup *to)
> +{
> +	struct mem_cgroup_per_zone *from_mz, *to_mz;
> +	int nid, zid;
> +	int ret = 1;
> +
> +	VM_BUG_ON(!irqs_disabled());
> +
> +	nid = page_to_nid(page);
> +	zid = page_zonenum(page);
> +	from_mz =  mem_cgroup_zoneinfo(from, nid, zid);
> +	to_mz =  mem_cgroup_zoneinfo(to, nid, zid);
> +
> +	if (res_counter_charge(&to->res, PAGE_SIZE)) {
> +		/* Now, we assume no_limit...no failure here. */
> +		return ret;
> +	}
> +	if (!try_lock_page_cgroup(page)) {
> +		res_counter_uncharge(&to->res, PAGE_SIZE);
> +		return ret;
> +	}
> +
> +	if (page_get_page_cgroup(page) != pc) {
> +		res_counter_uncharge(&to->res, PAGE_SIZE);
> +		goto out;
> +	}
> +
> +	if (spin_trylock(&to_mz->lru_lock)) {
> +		__mem_cgroup_remove_list(from_mz, pc);
> +		css_put(&from->css);
> +		res_counter_uncharge(&from->res, PAGE_SIZE);
> +		pc->mem_cgroup = to;
> +		css_get(&to->css);
> +		__mem_cgroup_add_list(to_mz, pc);
> +		ret = 0;
> +		spin_unlock(&to_mz->lru_lock);
> +	} else {
> +		res_counter_uncharge(&to->res, PAGE_SIZE);
> +	}
> +out:
> +	unlock_page_cgroup(page);
> +
> +	return ret;
> +}
> +
>  /*
>   * Charge the memory controller for page usage.
>   * Return
>  	__mem_cgroup_remove_list(mz, pc);
>  	spin_unlock_irqrestore(&mz->lru_lock, flags);
>  
>  	page_assign_page_cgroup(page, NULL);
>  	unlock_page_cgroup(page);
>  
> -	mem = pc->mem_cgroup;
> +
>  	res_counter_uncharge(&mem->res, PAGE_SIZE);
>  	css_put(&mem->css);
>  
> 

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Re: [PATCH 7/12] memcg add function to move account

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 16:30:50 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> > @@ -444,9 +445,14 @@ void mem_cgroup_move_lists(struct page *
> >  
> >  	pc = page_get_page_cgroup(page);
> >  	if (pc) {
> > +		mem = pc->mem_cgroup;
> >  		mz = page_cgroup_zoneinfo(pc);
> >  		spin_lock_irqsave(&mz->lru_lock, flags);
> > -		__mem_cgroup_move_lists(pc, lru);
> > +		/*
> > +		 * check against the race with move_account.
> > +		 */
> > +		if (likely(mem == pc->mem_cgroup))
> > +			__mem_cgroup_move_lists(pc, lru);
> 
> (snip)
> 
> > @@ -754,16 +824,24 @@ __mem_cgroup_uncharge_common(struct page
> >  	if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
> >  	    && ((PageCgroupCache(pc) || page_mapped(page))))
> >  		goto unlock;
> > -
> > +retry:
> > +	mem = pc->mem_cgroup;
> >  	mz = page_cgroup_zoneinfo(pc);
> >  	spin_lock_irqsave(&mz->lru_lock, flags);
> > +	if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED &&
> > +	    unlikely(mem != pc->mem_cgroup)) {
> > +		/* MAPPED account can be done without lock_page().
> > +		   Check race with mem_cgroup_move_account() */
> > +		spin_unlock_irqrestore(&mz->lru_lock, flags);
> > +		goto retry;
> > +	}
> 
> I'm sorry, but I've not been convinced yet why these checks are needed here.
> (Those checks are removed by [9/12] anyway.)
> 
> IIUC, pc->mem_cgroup is moved to another group only by mem_cgroup_move_account
> under lock_page_cgroup( and mz->lru_lock).
> And those two above(mem_cgroup_move_lists and __mem_cgroup_uncharge_common) sets
> mem = pc->mem_cgroup under lock_page_cgroup, so I don't think those checks
> (mem != pc->mem_cgroup) is needed.
> 
you're right.

Thanks,
-Kame



> 
> Thanks,
> Daisuke Nishimura.
> 
> > +/**
> > + * mem_cgroup_move_account - move account of the page
> > + * @page ... the target page of being moved.
> > + * @pc   ... page_cgroup of the page.
> > + * @from ... mem_cgroup which the page is moved from.
> > + * @to   ... mem_cgroup which the page is moved to.
> > + *
> > + * The caller must confirm following.
> > + * 1. disable irq.
> > + * 2. lru_lock of old mem_cgroup should be held.
> > + * 3. pc is guaranteed to be valid and on mem_cgroup's LRU.
> > + *
> > + * Because we cannot call try_to_free_page() here, the caller must guarantee
> > + * this moving of charge never fails. (if charge fails, this call fails.)
> > + * Currently this is called only against root cgroup.
> > + * which has no limitation of resource.
> > + * Returns 0 at success, returns 1 at failure.
> > + */
> > +int mem_cgroup_move_account(struct page *page, struct page_cgroup *pc,
> > +	struct mem_cgroup *from, struct mem_cgroup *to)
> > +{
> > +	struct mem_cgroup_per_zone *from_mz, *to_mz;
> > +	int nid, zid;
> > +	int ret = 1;
> > +
> > +	VM_BUG_ON(!irqs_disabled());
> > +
> > +	nid = page_to_nid(page);
> > +	zid = page_zonenum(page);
> > +	from_mz =  mem_cgroup_zoneinfo(from, nid, zid);
> > +	to_mz =  mem_cgroup_zoneinfo(to, nid, zid);
> > +
> > +	if (res_counter_charge(&to->res, PAGE_SIZE)) {
> > +		/* Now, we assume no_limit...no failure here. */
> > +		return ret;
> > +	}
> > +	if (!try_lock_page_cgroup(page)) {
> > +		res_counter_uncharge(&to->res, PAGE_SIZE);
> > +		return ret;
> > +	}
> > +
> > +	if (page_get_page_cgroup(page) != pc) {
> > +		res_counter_uncharge(&to->res, PAGE_SIZE);
> > +		goto out;
> > +	}
> > +
> > +	if (spin_trylock(&to_mz->lru_lock)) {
> > +		__mem_cgroup_remove_list(from_mz, pc);
> > +		css_put(&from->css);
> > +		res_counter_uncharge(&from->res, PAGE_SIZE);
> > +		pc->mem_cgroup = to;
> > +		css_get(&to->css);
> > +		__mem_cgroup_add_list(to_mz, pc);
> > +		ret = 0;
> > +		spin_unlock(&to_mz->lru_lock);
> > +	} else {
> > +		res_counter_uncharge(&to->res, PAGE_SIZE);
> > +	}
> > +out:
> > +	unlock_page_cgroup(page);
> > +
> > +	return ret;
> > +}
> > +
> >  /*
> >   * Charge the memory controller for page usage.
> >   * Return
> >  	__mem_cgroup_remove_list(mz, pc);
> >  	spin_unlock_irqrestore(&mz->lru_lock, flags);
> >  
> >  	page_assign_page_cgroup(page, NULL);
> >  	unlock_page_cgroup(page);
> >  
> > -	mem = pc->mem_cgroup;
> > +
> >  	res_counter_uncharge(&mem->res, PAGE_SIZE);
> >  	css_put(&mem->css);
> >  
> > 
> 

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Re: [PATCH 7/12] memcg add function to move account

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> This patch provides a function to move account information of a page between
> mem_cgroups.
> 

What is the interface for moving the accounting? Is it an explicit call like
force_empty? The other concern I have is about merging two LRU lists, when we
move LRU pages from one mem_cgroup to another, where do we add them? To the head
or tail? I think we need to think about it and document it well.

The other thing is that once we have mult-hierarchy support (which we really
need), we need to move the accounting to the parent instead of root.

> This moving of page_cgroup is done under
>  - lru_lock of source/destination mem_cgroup is held.

I suppose you mean and instead of either for the lru_lock

>  - lock_page_cgroup() is held.
> 
> Then, a routine which touches pc->mem_cgroup without lock_page_cgroup() should
> confirm pc->mem_cgroup is still valid or not. Typlical code can be following.
> 
> (while page is not under lock_page())
> 	mem = pc->mem_cgroup;
> 	mz = page_cgroup_zoneinfo(pc)
> 	spin_lock_irqsave(&mz->lru_lock);
> 	if (pc->mem_cgroup == mem)
> 		...../* some list handling */
> 	spin_unlock_irq(&mz->lru_lock);
> 
> Or better way is
> 	lock_page_cgroup(pc);
> 	....
> 	unlock_page_cgroup(pc);
> 
> But you should confirm the nest of lock and avoid deadlock.
> (trylock is better if it's ok.)
> 
> If you find page_cgroup from mem_cgroup's LRU under mz->lru_lock,
> you don't have to worry about what pc->mem_cgroup points to.
> 
> Changelog: (v4) -> (v5)
>   - check for lock_page() is removed.
>   - rewrote description.
> 
> Changelog: (v2) -> (v4)
>   - added lock_page_cgroup().
>   - splitted out from new-force-empty patch.
>   - added how-to-use text.
>   - fixed race in __mem_cgroup_uncharge_common().
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
>  mm/memcontrol.c |   84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 81 insertions(+), 3 deletions(-)
> 
> Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
> ===================================================================
> --- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
> +++ mmotm-2.6.27-rc7+/mm/memcontrol.c
> @@ -426,6 +426,7 @@ int task_in_mem_cgroup(struct task_struc
>  void mem_cgroup_move_lists(struct page *page, enum lru_list lru)
>  {
>  	struct page_cgroup *pc;
> +	struct mem_cgroup *mem;
>  	struct mem_cgroup_per_zone *mz;
>  	unsigned long flags;
> 
> @@ -444,9 +445,14 @@ void mem_cgroup_move_lists(struct page *
> 
>  	pc = page_get_page_cgroup(page);
>  	if (pc) {
> +		mem = pc->mem_cgroup;
>  		mz = page_cgroup_zoneinfo(pc);
>  		spin_lock_irqsave(&mz->lru_lock, flags);
> -		__mem_cgroup_move_lists(pc, lru);
> +		/*
> +		 * check against the race with move_account.
> +		 */
> +		if (likely(mem == pc->mem_cgroup))
> +			__mem_cgroup_move_lists(pc, lru);
>  		spin_unlock_irqrestore(&mz->lru_lock, flags);
>  	}
>  	unlock_page_cgroup(page);
> @@ -567,6 +573,70 @@ unsigned long mem_cgroup_isolate_pages(u
>  	return nr_taken;
>  }
> 
> +/**
> + * mem_cgroup_move_account - move account of the page
> + * @page ... the target page of being moved.
> + * @pc   ... page_cgroup of the page.
> + * @from ... mem_cgroup which the page is moved from.
> + * @to   ... mem_cgroup which the page is moved to.
> + *
> + * The caller must confirm following.
> + * 1. disable irq.
> + * 2. lru_lock of old mem_cgroup should be held.
> + * 3. pc is guaranteed to be valid and on mem_cgroup's LRU.
> + *
> + * Because we cannot call try_to_free_page() here, the caller must guarantee
> + * this moving of charge never fails. (if charge fails, this call fails.)
> + * Currently this is called only against root cgroup.
> + * which has no limitation of resource.
> + * Returns 0 at success, returns 1 at failure.
> + */
> +int mem_cgroup_move_account(struct page *page, struct page_cgroup *pc,
> +	struct mem_cgroup *from, struct mem_cgroup *to)
> +{
> +	struct mem_cgroup_per_zone *from_mz, *to_mz;
> +	int nid, zid;
> +	int ret = 1;
> +
> +	VM_BUG_ON(!irqs_disabled());
> +
> +	nid = page_to_nid(page);
> +	zid = page_zonenum(page);
> +	from_mz =  mem_cgroup_zoneinfo(from, nid, zid);
> +	to_mz =  mem_cgroup_zoneinfo(to, nid, zid);
> +
> +	if (res_counter_charge(&to->res, PAGE_SIZE)) {
> +		/* Now, we assume no_limit...no failure here. */
> +		return ret;
> +	}

Please BUG_ON() if the charging fails, we can be sure we catch assumptions that
are broken.

> +	if (!try_lock_page_cgroup(page)) {
> +		res_counter_uncharge(&to->res, PAGE_SIZE);
> +		return ret;
> +	}
> +
> +	if (page_get_page_cgroup(page) != pc) {
> +		res_counter_uncharge(&to->res, PAGE_SIZE);
> +		goto out;
> +	}
> +
> +	if (spin_trylock(&to_mz->lru_lock)) {

The spin_trylock is to avoid deadlocks, right?

> +		__mem_cgroup_remove_list(from_mz, pc);
> +		css_put(&from->css);
> +		res_counter_uncharge(&from->res, PAGE_SIZE);
> +		pc->mem_cgroup = to;
> +		css_get(&to->css);
> +		__mem_cgroup_add_list(to_mz, pc);
> +		ret = 0;
> +		spin_unlock(&to_mz->lru_lock);
> +	} else {
> +		res_counter_uncharge(&to->res, PAGE_SIZE);
> +	}
> +out:
> +	unlock_page_cgroup(page);
> +
> +	return ret;
> +}
> +
>  /*
>   * Charge the memory controller for page usage.
>   * Return
> @@ -754,16 +824,24 @@ __mem_cgroup_uncharge_common(struct page
>  	if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
>  	    && ((PageCgroupCache(pc) || page_mapped(page))))
>  		goto unlock;
> -
> +retry:
> +	mem = pc->mem_cgroup;
>  	mz = page_cgroup_zoneinfo(pc);
>  	spin_lock_irqsave(&mz->lru_lock, flags);
> +	if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED &&
> +	    unlikely(mem != pc->mem_cgroup)) {
> +		/* MAPPED account can be done without lock_page().
> +		   Check race with mem_cgroup_move_account() */

Coding style above is broken. Can this race really occur? Why do we get mem
before acquiring the mz->lru_lock? We don't seem to be using it.

> +		spin_unlock_irqrestore(&mz->lru_lock, flags);
> +		goto retry;
> +	}
>  	__mem_cgroup_remove_list(mz, pc);
>  	spin_unlock_irqrestore(&mz->lru_lock, flags);
> 
>  	page_assign_page_cgroup(page, NULL);
>  	unlock_page_cgroup(page);
> 
> -	mem = pc->mem_cgroup;
> +
>  	res_counter_uncharge(&mem->res, PAGE_SIZE);
>  	css_put(&mem->css);
> 
> 


-- 
	Balbir

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Re: Re: [PATCH 7/12] memcg add function to move account

[kamezawa.hiroyu]

----- Original Message -----

>KAMEZAWA Hiroyuki wrote:
>> This patch provides a function to move account information of a page betwee
n
>> mem_cgroups.
>> 
>
>What is the interface for moving the accounting? Is it an explicit call like
>force_empty?

My final purpose is moving account at attach_task().

> The other concern I have is about merging two LRU lists, when we
>move LRU pages from one mem_cgroup to another, where do we add them? 
> To the head
>or tail? I think we need to think about it and document it well.
>
Hmm, good point. considering force_empty, head is better.
(But I don't think about this seriously because I assumed root cgroup
 is unlimited)

I don't think this kind of internal behavior should not be documented as UI
while it's hot.

>The other thing is that once we have mult-hierarchy support (which we really
>need), we need to move the accounting to the parent instead of root.
>
yes. of course. please do as you like if this goes.
adding logic to do so needs more patch, so please wait.

But, IMHO, just use try_to_free_pages() is better for hierarchy, maybe.

>> This moving of page_cgroup is done under
>>  - lru_lock of source/destination mem_cgroup is held.
>
>I suppose you mean and instead of either for the lru_lock
>
I'll fix this comment.

>>  - lock_page_cgroup() is held.
>> 
>> Then, a routine which touches pc->mem_cgroup without lock_page_cgroup() sho
uld
>> confirm pc->mem_cgroup is still valid or not. Typlical code can be followin
g.
>> 
>> (while page is not under lock_page())
>> 	mem = pc->mem_cgroup;
>> 	mz = page_cgroup_zoneinfo(pc)
>> 	spin_lock_irqsave(&mz->lru_lock);
>> 	if (pc->mem_cgroup == mem)
>> 		...../* some list handling */
>> 	spin_unlock_irq(&mz->lru_lock);
>> 
>> Or better way is
>> 	lock_page_cgroup(pc);
>> 	....
>> 	unlock_page_cgroup(pc);
>> 
>> But you should confirm the nest of lock and avoid deadlock.
>> (trylock is better if it's ok.)
>> 
>> If you find page_cgroup from mem_cgroup's LRU under mz->lru_lock,
>> you don't have to worry about what pc->mem_cgroup points to.
>> 
>> Changelog: (v4) -> (v5)
>>   - check for lock_page() is removed.
>>   - rewrote description.
>> 
>> Changelog: (v2) -> (v4)
>>   - added lock_page_cgroup().
>>   - splitted out from new-force-empty patch.
>>   - added how-to-use text.
>>   - fixed race in __mem_cgroup_uncharge_common().
>> 
>> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>> 
>>  mm/memcontrol.c |   84 +++++++++++++++++++++++++++++++++++++++++++++++++++
+++--
>>  1 file changed, 81 insertions(+), 3 deletions(-)
>> 
>> Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
>> ===================================================================
>> --- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
>> +++ mmotm-2.6.27-rc7+/mm/memcontrol.c
>> @@ -426,6 +426,7 @@ int task_in_mem_cgroup(struct task_struc
>>  void mem_cgroup_move_lists(struct page *page, enum lru_list lru)
>>  {
>>  	struct page_cgroup *pc;
>> +	struct mem_cgroup *mem;
>>  	struct mem_cgroup_per_zone *mz;
>>  	unsigned long flags;
>> 
>> @@ -444,9 +445,14 @@ void mem_cgroup_move_lists(struct page *
>> 
>>  	pc = page_get_page_cgroup(page);
>>  	if (pc) {
>> +		mem = pc->mem_cgroup;
>>  		mz = page_cgroup_zoneinfo(pc);
>>  		spin_lock_irqsave(&mz->lru_lock, flags);
>> -		__mem_cgroup_move_lists(pc, lru);
>> +		/*
>> +		 * check against the race with move_account.
>> +		 */
>> +		if (likely(mem == pc->mem_cgroup))
>> +			__mem_cgroup_move_lists(pc, lru);
>>  		spin_unlock_irqrestore(&mz->lru_lock, flags);
>>  	}
>>  	unlock_page_cgroup(page);
>> @@ -567,6 +573,70 @@ unsigned long mem_cgroup_isolate_pages(u
>>  	return nr_taken;
>>  }
>> 
>> +/**
>> + * mem_cgroup_move_account - move account of the page
>> + * @page ... the target page of being moved.
>> + * @pc   ... page_cgroup of the page.
>> + * @from ... mem_cgroup which the page is moved from.
>> + * @to   ... mem_cgroup which the page is moved to.
>> + *
>> + * The caller must confirm following.
>> + * 1. disable irq.
>> + * 2. lru_lock of old mem_cgroup should be held.
>> + * 3. pc is guaranteed to be valid and on mem_cgroup's LRU.
>> + *
>> + * Because we cannot call try_to_free_page() here, the caller must guarant
ee
>> + * this moving of charge never fails. (if charge fails, this call fails.)
>> + * Currently this is called only against root cgroup.
>> + * which has no limitation of resource.
>> + * Returns 0 at success, returns 1 at failure.
>> + */
>> +int mem_cgroup_move_account(struct page *page, struct page_cgroup *pc,
>> +	struct mem_cgroup *from, struct mem_cgroup *to)
>> +{
>> +	struct mem_cgroup_per_zone *from_mz, *to_mz;
>> +	int nid, zid;
>> +	int ret = 1;
>> +
>> +	VM_BUG_ON(!irqs_disabled());
>> +
>> +	nid = page_to_nid(page);
>> +	zid = page_zonenum(page);
>> +	from_mz =  mem_cgroup_zoneinfo(from, nid, zid);
>> +	to_mz =  mem_cgroup_zoneinfo(to, nid, zid);
>> +
>> +	if (res_counter_charge(&to->res, PAGE_SIZE)) {
>> +		/* Now, we assume no_limit...no failure here. */
>> +		return ret;
>> +	}
>
>Please BUG_ON() if the charging fails, we can be sure we catch assumptions
> are broken.
>
I'll remove this charge() and change protocol to be 
"the page should be pre-charged to destination cgroup before calling move."


>> +	if (!try_lock_page_cgroup(page)) {
>> +		res_counter_uncharge(&to->res, PAGE_SIZE);
>> +		return ret;
>> +	}
>> +
>> +	if (page_get_page_cgroup(page) != pc) {
>> +		res_counter_uncharge(&to->res, PAGE_SIZE);
>> +		goto out;
>> +	}
>> +
>> +	if (spin_trylock(&to_mz->lru_lock)) {
>
>The spin_trylock is to avoid deadlocks, right?
>
yes.

>> +		__mem_cgroup_remove_list(from_mz, pc);
>> +		css_put(&from->css);
>> +		res_counter_uncharge(&from->res, PAGE_SIZE);
>> +		pc->mem_cgroup = to;
>> +		css_get(&to->css);
>> +		__mem_cgroup_add_list(to_mz, pc);
>> +		ret = 0;
>> +		spin_unlock(&to_mz->lru_lock);
>> +	} else {
>> +		res_counter_uncharge(&to->res, PAGE_SIZE);
>> +	}
>> +out:
>> +	unlock_page_cgroup(page);
>> +
>> +	return ret;
>> +}
>> +
>>  /*
>>   * Charge the memory controller for page usage.
>>   * Return
>> @@ -754,16 +824,24 @@ __mem_cgroup_uncharge_common(struct page
>>  	if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
>>  	    && ((PageCgroupCache(pc) || page_mapped(page))))
>>  		goto unlock;
>> -
>> +retry:
>> +	mem = pc->mem_cgroup;
>>  	mz = page_cgroup_zoneinfo(pc);
>>  	spin_lock_irqsave(&mz->lru_lock, flags);
>> +	if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED &&
>> +	    unlikely(mem != pc->mem_cgroup)) {
>> +		/* MAPPED account can be done without lock_page().
>> +		   Check race with mem_cgroup_move_account() */
>
>Coding style above is broken.
will fix.

>Can this race really occur?
yes, I think so. please check SwapCache behavior.
But This check may disappear after I rewrite the whole series.

>Why do we get mem before acquiring the mz->lru_lock? We don't seem to 
>be using it.
It's costly to call page_cgroup_zoneinfo() again. so just saves mem and
compare pc->mem_cgroup.

Thanks,
-Kame

>> +		spin_unlock_irqrestore(&mz->lru_lock, flags);
>> +		goto retry;
>> +	}
>>  	__mem_cgroup_remove_list(mz, pc);
>>  	spin_unlock_irqrestore(&mz->lru_lock, flags);
>> 
>>  	page_assign_page_cgroup(page, NULL);
>>  	unlock_page_cgroup(page);
>> 
>> -	mem = pc->mem_cgroup;
>> +
>>  	res_counter_uncharge(&mem->res, PAGE_SIZE);
>>  	css_put(&mem->css);
>> 
>> 
>
>
>-- 
>	Balbir

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[PATCH 8/12] memcg rewrite force empty to move account to root

[KAMEZAWA Hiroyuki]

Current force_empty of memory resource controller just removes page_cgroup.
This maans the page is never accounted at all and create an in-use page which
has no page_cgroup.

This patch tries to move account to "root" cgroup. By this patch, force_empty
doesn't leak an account but move account to "root" cgroup. Maybe someone can
think of other enhancements as moving account to its parent.
(But moving to the parent means we have to handle "limit" of pages.
 Need more complicated work to do that.)

For now, just moves account to root cgroup.

Note: all lock other than old mem_cgroup's lru_lock
      in this path is try_lock().

Changelog (v4) -> (5)
 - removed yield()
 - remove lock_page().
 - use list_for_each_entry_safe() instead of list_empty() loop.
 - check list is empty or not rather than see usage.
 - added lru_add_drain_all() at the start of loops.

Changelog (v2) -> (v4)
 - splitted out mem_cgroup_move_account().
 - replaced get_page() with get_page_unless_zero().
   (This is necessary for avoiding confliction with migration)

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 Documentation/controllers/memory.txt |    7 ++-
 mm/memcontrol.c                      |   68 ++++++++++++++++++++---------------
 2 files changed, 43 insertions(+), 32 deletions(-)

Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -29,10 +29,12 @@
 #include <linux/slab.h>
 #include <linux/swap.h>
 #include <linux/spinlock.h>
+#include <linux/pagemap.h>
 #include <linux/fs.h>
 #include <linux/seq_file.h>
 #include <linux/vmalloc.h>
 #include <linux/mm_inline.h>
+#include <linux/writeback.h>
 
 #include <asm/uaccess.h>
 
@@ -979,45 +981,34 @@ int mem_cgroup_resize_limit(struct mem_c
 
 
 /*
- * This routine traverse page_cgroup in given list and drop them all.
- * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
+ * This routine traverse page_cgroup in given list and move them all.
  */
-#define FORCE_UNCHARGE_BATCH	(128)
 static void mem_cgroup_force_empty_list(struct mem_cgroup *mem,
 			    struct mem_cgroup_per_zone *mz,
 			    enum lru_list lru)
 {
-	struct page_cgroup *pc;
+	struct page_cgroup *pc, *tmp;
 	struct page *page;
-	int count = FORCE_UNCHARGE_BATCH;
 	unsigned long flags;
 	struct list_head *list;
 
 	list = &mz->lists[lru];
 
 	spin_lock_irqsave(&mz->lru_lock, flags);
-	while (!list_empty(list)) {
-		pc = list_entry(list->prev, struct page_cgroup, lru);
+	list_for_each_entry_safe(pc, tmp, list, lru) {
 		page = pc->page;
-		get_page(page);
-		spin_unlock_irqrestore(&mz->lru_lock, flags);
-		/*
-		 * Check if this page is on LRU. !LRU page can be found
-		 * if it's under page migration.
-		 */
-		if (PageLRU(page)) {
-			__mem_cgroup_uncharge_common(page,
-					MEM_CGROUP_CHARGE_TYPE_FORCE);
-			put_page(page);
-			if (--count <= 0) {
-				count = FORCE_UNCHARGE_BATCH;
-				cond_resched();
-			}
-		} else
-			cond_resched();
-		spin_lock_irqsave(&mz->lru_lock, flags);
+		/* For avoiding race with speculative page cache handling. */
+		if (!PageLRU(page) || !get_page_unless_zero(page)) {
+			continue;
+		}
+		mem_cgroup_move_account(page, pc, mem, &init_mem_cgroup);
+		put_page(page);
+		if (atomic_read(&mem->css.cgroup->count) > 0)
+			break;
 	}
 	spin_unlock_irqrestore(&mz->lru_lock, flags);
+
+	cond_resched();
 }
 
 /*
@@ -1027,7 +1018,9 @@ static void mem_cgroup_force_empty_list(
 static int mem_cgroup_force_empty(struct mem_cgroup *mem)
 {
 	int ret = -EBUSY;
-	int node, zid;
+	int node, zid, busy;
+	struct mem_cgroup_per_zone *mz;
+	enum lru_list l;
 
 	css_get(&mem->css);
 	/*
@@ -1035,17 +1028,34 @@ static int mem_cgroup_force_empty(struct
 	 * active_list <-> inactive_list while we don't take a lock.
 	 * So, we have to do loop here until all lists are empty.
 	 */
-	while (mem->res.usage > 0) {
+	busy = 1;
+
+	while (busy) {
 		if (atomic_read(&mem->css.cgroup->count) > 0)
 			goto out;
-		for_each_node_state(node, N_POSSIBLE)
+		/*
+		 * While walking our own LRU, we also checks LRU bit on page.
+		 * If a page is on pagevec, it's not on LRU and we cannot
+		 * grab it. Calling lru_add_drain_all() here.
+		 */
+		lru_add_drain_all();
+		for_each_node_state(node, N_HIGH_MEMORY) {
 			for (zid = 0; zid < MAX_NR_ZONES; zid++) {
-				struct mem_cgroup_per_zone *mz;
-				enum lru_list l;
 				mz = mem_cgroup_zoneinfo(mem, node, zid);
 				for_each_lru(l)
 					mem_cgroup_force_empty_list(mem, mz, l);
 			}
+		}
+		busy = 0;
+		for_each_node_state(node, N_HIGH_MEMORY) {
+			for (zid = 0; !busy && zid < MAX_NR_ZONES; zid++) {
+				mz = mem_cgroup_zoneinfo(mem, node, zid);
+				for_each_lru(l)
+					busy |= !list_empty(&mz->lists[l]);
+			}
+			if (busy)
+				break;
+		}
 	}
 	ret = 0;
 out:
Index: mmotm-2.6.27-rc7+/Documentation/controllers/memory.txt
===================================================================
--- mmotm-2.6.27-rc7+.orig/Documentation/controllers/memory.txt
+++ mmotm-2.6.27-rc7+/Documentation/controllers/memory.txt
@@ -207,7 +207,8 @@ The memory.force_empty gives an interfac
 
 # echo 1 > memory.force_empty
 
-will drop all charges in cgroup. Currently, this is maintained for test.
+will move all charges to root cgroup.
+(This policy may be modified in future.)
 
 4. Testing
 
@@ -238,8 +239,8 @@ reclaimed.
 
 A cgroup can be removed by rmdir, but as discussed in sections 4.1 and 4.2, a
 cgroup might have some charge associated with it, even though all
-tasks have migrated away from it. Such charges are automatically dropped at
-rmdir() if there are no tasks.
+tasks have migrated away from it. Such charges are automatically moved to
+root cgroup at rmidr() if there are no tasks. (This policy may be changed.)
 
 5. TODO
 

[PATCH 9/12] memcg allocate all page_cgroup at boot

[KAMEZAWA Hiroyuki]

Allocate all page_cgroup at boot and remove page_cgroup poitner
from struct page. This patch adds an interface as

 struct page_cgroup *lookup_page_cgroup(struct page*)

All FLATMEM/DISCONTIGMEM/SPARSEMEM  and MEMORY_HOTPLUG is supported.

Remove page_cgroup pointer reduces the amount of memory by
 - 4 bytes per PAGE_SIZE.
 - 8 bytes per PAGE_SIZE
if memory controller is disabled. (even if configured.)
meta data usage of this is no problem in FLATMEM/DISCONTIGMEM.
On SPARSEMEM, this makes mem_section[] size twice.

On usual 8GB x86-32 server, this saves 8MB of NORMAL_ZONE memory.
On my x86-64 server with 48GB of memory, this saves 96MB of memory.
(and uses xx kbytes for mem_section.)
I think this reduction makes sense.

By pre-allocation, kmalloc/kfree in charge/uncharge are removed. 
This means
  - we're not necessary to be afraid of kmalloc faiulre.
    (this can happen because of gfp_mask type.)
  - we can avoid calling kmalloc/kfree.
  - we can avoid allocating tons of small objects which can be fragmented.
  - we can know what amount of memory will be used for this extra-lru handling.

I added printk message as

	"allocated %ld bytes of page_cgroup"
        "please try cgroup_disable=memory option if you don't want"

maybe enough informative for users.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 include/linux/memcontrol.h  |   11 -
 include/linux/mm_types.h    |    4 
 include/linux/mmzone.h      |    9 +
 include/linux/page_cgroup.h |   90 +++++++++++++++
 mm/Makefile                 |    2 
 mm/memcontrol.c             |  258 ++++++++++++--------------------------------
 mm/page_alloc.c             |   12 --
 mm/page_cgroup.c            |  253 +++++++++++++++++++++++++++++++++++++++++++
 8 files changed, 431 insertions(+), 208 deletions(-)

Index: mmotm-2.6.27-rc7+/mm/page_cgroup.c
===================================================================
--- /dev/null
+++ mmotm-2.6.27-rc7+/mm/page_cgroup.c
@@ -0,0 +1,253 @@
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/bootmem.h>
+#include <linux/bit_spinlock.h>
+#include <linux/page_cgroup.h>
+#include <linux/hash.h>
+#include <linux/memory.h>
+
+static void __meminit
+__init_page_cgroup(struct page_cgroup *pc, unsigned long pfn)
+{
+	pc->flags = 0;
+	pc->mem_cgroup = NULL;
+	pc->page = pfn_to_page(pfn);
+}
+static unsigned long total_usage = 0;
+
+#ifdef CONFIG_FLAT_NODE_MEM_MAP
+
+
+void __init pgdat_page_cgroup_init(struct pglist_data *pgdat)
+{
+	pgdat->node_page_cgroup = NULL;
+}
+
+struct page_cgroup *lookup_page_cgroup(struct page *page)
+{
+	unsigned long pfn = page_to_pfn(page);
+	unsigned long offset;
+	struct page_cgroup *base;
+
+	base = NODE_DATA(page_to_nid(nid))->node_page_cgroup;
+	if (unlikely(!base))
+		return NULL;
+
+	offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
+	return base + offset;
+}
+
+static int __init alloc_node_page_cgroup(int nid)
+{
+	struct page_cgroup *base, *pc;
+	unsigned long table_size;
+	unsigned long start_pfn, nr_pages, index;
+
+	start_pfn = NODE_DATA(nid)->node_start_pfn;
+	nr_pages = NODE_DATA(nid)->node_spanned_pages;
+
+	table_size = sizeof(struct page_cgroup) * nr_pages;
+
+	base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
+			table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
+	if (!base)
+		return -ENOMEM;
+	for (index = 0; index < nr_pages; index++) {
+		pc = base + index;
+		__init_page_cgroup(pc, start_pfn + index);
+	}
+	NODE_DATA(nid)->node_page_cgroup = base;
+	total_usage += table_size;
+	return 0;
+}
+
+void __init free_node_page_cgroup(int nid)
+{
+	unsigned long table_size;
+	unsigned long nr_pages;
+	struct page_cgroup *base;
+
+	base = NODE_DATA(nid)->node_page_cgroup;
+	if (!base)
+		return;
+	nr_pages = NODE_DATA(nid)->node_spanned_pages;
+
+	table_size = sizeof(struct page_cgroup) * nr_pages;
+
+	free_bootmem_node(NODE_DATA(nid),
+			(unsigned long)base, table_size);
+	NODE_DATA(nid)->node_page_cgroup = NULL;
+}
+
+void __init page_cgroup_init(void)
+{
+
+	int nid, fail;
+
+	for_each_online_node(nid)  {
+		fail = alloc_node_page_cgroup(nid);
+		if (fail)
+			goto fail;
+	}
+	printk("allocated %ld bytes of page_cgroup\n", total_usage);
+	printk("please try cgroup_disable=memory option if you don't want\n");
+	return;
+fail:
+	printk("allocation of page_cgroup was failed.\n");
+	printk("please try cgroup_disable=memory boot option\n");
+	panic("Out of memory");
+}
+
+#else /* CONFIG_FLAT_NODE_MEM_MAP */
+
+struct page_cgroup *lookup_page_cgroup(struct page *page)
+{
+	unsigned long pfn = page_to_pfn(page);
+	struct mem_section *section = __pfn_to_section(pfn);
+
+	return section->page_cgroup + pfn;
+}
+
+int __meminit init_section_page_cgroup(unsigned long pfn)
+{
+	struct mem_section *section;
+	struct page_cgroup *base, *pc;
+	unsigned long table_size;
+	int nid, index;
+
+	section = __pfn_to_section(pfn);
+
+	if (section->page_cgroup)
+		return 0;
+
+	nid = page_to_nid(pfn_to_page(pfn));
+
+	table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
+	base = kmalloc_node(table_size, GFP_KERNEL, nid);
+	if (!base)
+		base = vmalloc_node(table_size, nid);
+
+	if (!base) {
+		printk("page cgroup allocation failure\n");
+		return -ENOMEM;
+	}
+
+	for (index = 0; index < PAGES_PER_SECTION; index++) {
+		pc = base + index;
+		__init_page_cgroup(pc, pfn + index);
+	}
+
+	section = __pfn_to_section(pfn);
+	section->page_cgroup = base - pfn;
+	total_usage += table_size;
+	return 0;
+}
+#ifdef CONFIG_MEMORY_HOTPLUG
+void __free_page_cgroup(unsigned long pfn)
+{
+	struct mem_section *ms;
+	struct page_cgroup *base;
+
+	ms = __pfn_to_section(pfn);
+	if (!ms || !ms->page_cgroup)
+		return;
+	base = ms->page_cgroup + pfn;
+	ms->page_cgroup = NULL;
+	if (is_vmalloc_addr(base))
+		vfree(base);
+	else
+		kfree(base);
+}
+
+int online_page_cgroup(unsigned long start_pfn,
+			unsigned long nr_pages,
+			int nid)
+{
+	unsigned long start, end, pfn;
+	int fail = 0;
+
+	start = start_pfn & (PAGES_PER_SECTION - 1);
+	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
+
+	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
+		if (!pfn_present(pfn))
+			continue;
+		fail = init_section_page_cgroup(pfn);
+	}
+	if (!fail)
+		return 0;
+
+	/* rollback */
+	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
+		__free_page_cgroup(pfn);
+
+	return -ENOMEM;
+}
+
+int offline_page_cgroup(unsigned long start_pfn,
+		unsigned long nr_pages, int nid)
+{
+	unsigned long start, end, pfn;
+
+	start = start_pfn & (PAGES_PER_SECTION - 1);
+	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
+
+	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
+                __free_page_cgroup(pfn);
+	return 0;
+
+}
+
+static int page_cgroup_callback(struct notifier_block *self,
+			       unsigned long action, void *arg)
+{
+	struct memory_notify *mn = arg;
+	int ret = 0;
+	switch (action) {
+	case MEM_GOING_ONLINE:
+		ret = online_page_cgroup(mn->start_pfn,
+				   mn->nr_pages, mn->status_change_nid);
+		break;
+	case MEM_CANCEL_ONLINE:
+	case MEM_OFFLINE:
+		offline_page_cgroup(mn->start_pfn,
+				mn->nr_pages, mn->status_change_nid);
+		break;
+	case MEM_GOING_OFFLINE:
+		break;
+        case MEM_ONLINE:
+	case MEM_CANCEL_OFFLINE:
+		break;
+	}
+	ret = notifier_from_errno(ret);
+	return ret;
+}
+
+#endif
+
+void __init page_cgroup_init(void)
+{
+	unsigned long pfn;
+	int fail = 0;
+
+	for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) {
+		if (!pfn_present(pfn))
+			continue;
+		fail = init_section_page_cgroup(pfn);
+	}
+	if (fail) {
+		printk("please try cgroup_disable=memory boot option\n");
+		panic("Out of memory");
+	} else {
+		hotplug_memory_notifier(page_cgroup_callback, 0);
+	}
+	printk("allocated %ld bytes of page_cgroup\n", total_usage);
+	printk("please try cgroup_disable=memory option if you don't want\n");
+}
+
+void __init pgdat_page_cgroup_init(struct pglist_data *pgdat)
+{
+	return;
+}
+
+#endif
Index: mmotm-2.6.27-rc7+/include/linux/mm_types.h
===================================================================
--- mmotm-2.6.27-rc7+.orig/include/linux/mm_types.h
+++ mmotm-2.6.27-rc7+/include/linux/mm_types.h
@@ -94,10 +94,6 @@ struct page {
 	void *virtual;			/* Kernel virtual address (NULL if
 					   not kmapped, ie. highmem) */
 #endif /* WANT_PAGE_VIRTUAL */
-#ifdef CONFIG_CGROUP_MEM_RES_CTLR
-	unsigned long page_cgroup;
-#endif
-
 #ifdef CONFIG_KMEMCHECK
 	void *shadow;
 #endif
Index: mmotm-2.6.27-rc7+/mm/Makefile
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/Makefile
+++ mmotm-2.6.27-rc7+/mm/Makefile
@@ -34,6 +34,6 @@ obj-$(CONFIG_FS_XIP) += filemap_xip.o
 obj-$(CONFIG_MIGRATION) += migrate.o
 obj-$(CONFIG_SMP) += allocpercpu.o
 obj-$(CONFIG_QUICKLIST) += quicklist.o
-obj-$(CONFIG_CGROUP_MEM_RES_CTLR) += memcontrol.o
+obj-$(CONFIG_CGROUP_MEM_RES_CTLR) += memcontrol.o page_cgroup.o
 obj-$(CONFIG_CGROUP_MEMRLIMIT_CTLR) += memrlimitcgroup.o
 obj-$(CONFIG_KMEMTRACE) += kmemtrace.o
Index: mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
===================================================================
--- /dev/null
+++ mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
@@ -0,0 +1,90 @@
+#ifndef __LINUX_PAGE_CGROUP_H
+#define __LINUX_PAGE_CGROUP_H
+#include <linux/bit_spinlock.h>
+/*
+ * Page Cgroup can be considered as an extended mem_map.
+ * A page_cgroup page is associated with every page descriptor. The
+ * page_cgroup helps us identify information about the cgroup
+ * All page cgroups are allocated at boot or memory hotplug event,
+ * then the page cgroup for pfn always exists.
+ */
+struct page_cgroup {
+	unsigned long flags;
+	struct mem_cgroup *mem_cgroup;
+	struct page *page;
+	struct list_head lru;		/* per cgroup LRU list */
+};
+
+void __init pgdat_page_cgroup_init(struct pglist_data *pgdat);
+void __init page_cgroup_init(void);
+struct page_cgroup *lookup_page_cgroup(struct page *page);
+
+enum {
+	/* flags for mem_cgroup */
+	PCG_LOCK,  /* page cgroup is locked */
+	PCG_CACHE, /* charged as cache */
+	PCG_USED, /* this object is in use. */
+	/* flags for LRU placement */
+	PCG_ACTIVE, /* page is active in this cgroup */
+	PCG_FILE, /* page is file system backed */
+	PCG_UNEVICTABLE, /* page is unevictableable */
+};
+
+#define TESTPCGFLAG(uname, lname)			\
+static inline int PageCgroup##uname(struct page_cgroup *pc)	\
+	{ return test_bit(PCG_##lname, &pc->flags); }
+
+#define SETPCGFLAG(uname, lname)			\
+static inline void SetPageCgroup##uname(struct page_cgroup *pc)\
+	{ set_bit(PCG_##lname, &pc->flags);  }
+
+#define CLEARPCGFLAG(uname, lname)			\
+static inline void ClearPageCgroup##uname(struct page_cgroup *pc)	\
+	{ clear_bit(PCG_##lname, &pc->flags);  }
+
+/* Cache flag is set only once (at allocation) */
+TESTPCGFLAG(Cache, CACHE)
+
+TESTPCGFLAG(Used, USED)
+CLEARPCGFLAG(Used, USED)
+
+/* LRU management flags (from global-lru definition) */
+TESTPCGFLAG(File, FILE)
+SETPCGFLAG(File, FILE)
+CLEARPCGFLAG(File, FILE)
+
+TESTPCGFLAG(Active, ACTIVE)
+SETPCGFLAG(Active, ACTIVE)
+CLEARPCGFLAG(Active, ACTIVE)
+
+TESTPCGFLAG(Unevictable, UNEVICTABLE)
+SETPCGFLAG(Unevictable, UNEVICTABLE)
+CLEARPCGFLAG(Unevictable, UNEVICTABLE)
+
+static inline int page_cgroup_nid(struct page_cgroup *pc)
+{
+	return page_to_nid(pc->page);
+}
+
+static inline enum zone_type page_cgroup_zid(struct page_cgroup *pc)
+{
+	return page_zonenum(pc->page);
+}
+
+static inline void lock_page_cgroup(struct page_cgroup *pc)
+{
+	bit_spin_lock(PCG_LOCK, &pc->flags);
+}
+
+static inline int trylock_page_cgroup(struct page_cgroup *pc)
+{
+	return bit_spin_trylock(PCG_LOCK, &pc->flags);
+}
+
+static inline void unlock_page_cgroup(struct page_cgroup *pc)
+{
+	bit_spin_unlock(PCG_LOCK, &pc->flags);
+}
+
+
+#endif
Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -35,11 +35,11 @@
 #include <linux/vmalloc.h>
 #include <linux/mm_inline.h>
 #include <linux/writeback.h>
+#include <linux/page_cgroup.h>
 
 #include <asm/uaccess.h>
 
 struct cgroup_subsys mem_cgroup_subsys __read_mostly;
-static struct kmem_cache *page_cgroup_cache __read_mostly;
 #define MEM_CGROUP_RECLAIM_RETRIES	5
 
 /*
@@ -139,80 +139,6 @@ static struct mem_cgroup init_mem_cgroup
 
 #define is_root_cgroup(cgrp)	((cgrp) == &init_mem_cgroup)
 
-
-/*
- * We use the lower bit of the page->page_cgroup pointer as a bit spin
- * lock.  We need to ensure that page->page_cgroup is at least two
- * byte aligned (based on comments from Nick Piggin).  But since
- * bit_spin_lock doesn't actually set that lock bit in a non-debug
- * uniprocessor kernel, we should avoid setting it here too.
- */
-#define PAGE_CGROUP_LOCK_BIT 	0x0
-#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
-#define PAGE_CGROUP_LOCK 	(1 << PAGE_CGROUP_LOCK_BIT)
-#else
-#define PAGE_CGROUP_LOCK	0x0
-#endif
-
-/*
- * A page_cgroup page is associated with every page descriptor. The
- * page_cgroup helps us identify information about the cgroup
- */
-struct page_cgroup {
-	struct list_head lru;		/* per cgroup LRU list */
-	struct page *page;
-	struct mem_cgroup *mem_cgroup;
-	unsigned long flags;
-};
-
-enum {
-	/* flags for mem_cgroup */
-	PCG_CACHE, /* charged as cache */
-	/* flags for LRU placement */
-	PCG_ACTIVE, /* page is active in this cgroup */
-	PCG_FILE, /* page is file system backed */
-	PCG_UNEVICTABLE, /* page is unevictableable */
-};
-
-#define TESTPCGFLAG(uname, lname)			\
-static inline int PageCgroup##uname(struct page_cgroup *pc)	\
-	{ return test_bit(PCG_##lname, &pc->flags); }
-
-#define SETPCGFLAG(uname, lname)			\
-static inline void SetPageCgroup##uname(struct page_cgroup *pc)\
-	{ set_bit(PCG_##lname, &pc->flags);  }
-
-#define CLEARPCGFLAG(uname, lname)			\
-static inline void ClearPageCgroup##uname(struct page_cgroup *pc)	\
-	{ clear_bit(PCG_##lname, &pc->flags);  }
-
-
-/* Cache flag is set only once (at allocation) */
-TESTPCGFLAG(Cache, CACHE)
-
-/* LRU management flags (from global-lru definition) */
-TESTPCGFLAG(File, FILE)
-SETPCGFLAG(File, FILE)
-CLEARPCGFLAG(File, FILE)
-
-TESTPCGFLAG(Active, ACTIVE)
-SETPCGFLAG(Active, ACTIVE)
-CLEARPCGFLAG(Active, ACTIVE)
-
-TESTPCGFLAG(Unevictable, UNEVICTABLE)
-SETPCGFLAG(Unevictable, UNEVICTABLE)
-CLEARPCGFLAG(Unevictable, UNEVICTABLE)
-
-static int page_cgroup_nid(struct page_cgroup *pc)
-{
-	return page_to_nid(pc->page);
-}
-
-static enum zone_type page_cgroup_zid(struct page_cgroup *pc)
-{
-	return page_zonenum(pc->page);
-}
-
 enum charge_type {
 	MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
 	MEM_CGROUP_CHARGE_TYPE_MAPPED,
@@ -223,9 +149,9 @@ enum charge_type {
 
 static const unsigned long
 pcg_default_flags[NR_CHARGE_TYPE] = {
-	((1 << PCG_CACHE) | (1 << PCG_FILE)),
-	((1 << PCG_ACTIVE)),
-	((1 << PCG_ACTIVE) | (1 << PCG_CACHE)),
+	(1 << PCG_CACHE) | (1 << PCG_FILE) | (1 << PCG_USED) | (1 << PCG_LOCK),
+	(1 << PCG_ACTIVE) | (1 << PCG_LOCK) | (1 << PCG_USED),
+	(1 << PCG_ACTIVE) | (1 << PCG_CACHE) | (1 << PCG_USED)|  (1 << PCG_LOCK),
 	0,
 };
 
@@ -308,37 +234,6 @@ struct mem_cgroup *mem_cgroup_from_task(
 				struct mem_cgroup, css);
 }
 
-static inline int page_cgroup_locked(struct page *page)
-{
-	return bit_spin_is_locked(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
-}
-
-static void page_assign_page_cgroup(struct page *page, struct page_cgroup *pc)
-{
-	VM_BUG_ON(!page_cgroup_locked(page));
-	page->page_cgroup = ((unsigned long)pc | PAGE_CGROUP_LOCK);
-}
-
-struct page_cgroup *page_get_page_cgroup(struct page *page)
-{
-	return (struct page_cgroup *) (page->page_cgroup & ~PAGE_CGROUP_LOCK);
-}
-
-static void lock_page_cgroup(struct page *page)
-{
-	bit_spin_lock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
-}
-
-static int try_lock_page_cgroup(struct page *page)
-{
-	return bit_spin_trylock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
-}
-
-static void unlock_page_cgroup(struct page *page)
-{
-	bit_spin_unlock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
-}
-
 static void __mem_cgroup_remove_list(struct mem_cgroup_per_zone *mz,
 			struct page_cgroup *pc)
 {
@@ -442,22 +337,19 @@ void mem_cgroup_move_lists(struct page *
 	 * safely get to page_cgroup without it, so just try_lock it:
 	 * mem_cgroup_isolate_pages allows for page left on wrong list.
 	 */
-	if (!try_lock_page_cgroup(page))
+	pc = lookup_page_cgroup(page);
+
+	if (!trylock_page_cgroup(pc))
 		return;
 
-	pc = page_get_page_cgroup(page);
-	if (pc) {
+	if (PageCgroupUsed(pc)) {
 		mem = pc->mem_cgroup;
 		mz = page_cgroup_zoneinfo(pc);
 		spin_lock_irqsave(&mz->lru_lock, flags);
-		/*
-		 * check against the race with move_account.
-		 */
-		if (likely(mem == pc->mem_cgroup))
-			__mem_cgroup_move_lists(pc, lru);
+		__mem_cgroup_move_lists(pc, lru);
 		spin_unlock_irqrestore(&mz->lru_lock, flags);
 	}
-	unlock_page_cgroup(page);
+	unlock_page_cgroup(pc);
 }
 
 /*
@@ -544,6 +436,8 @@ unsigned long mem_cgroup_isolate_pages(u
 	list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
 		if (scan >= nr_to_scan)
 			break;
+		if (unlikely(!PageCgroupUsed(pc)))
+			continue;
 		page = pc->page;
 
 		if (unlikely(!PageLRU(page)))
@@ -611,12 +505,12 @@ int mem_cgroup_move_account(struct page 
 		/* Now, we assume no_limit...no failure here. */
 		return ret;
 	}
-	if (!try_lock_page_cgroup(page)) {
+	if (!trylock_page_cgroup(pc)) {
 		res_counter_uncharge(&to->res, PAGE_SIZE);
 		return ret;
 	}
 
-	if (page_get_page_cgroup(page) != pc) {
+	if (!PageCgroupUsed(pc)) {
 		res_counter_uncharge(&to->res, PAGE_SIZE);
 		goto out;
 	}
@@ -634,7 +528,7 @@ int mem_cgroup_move_account(struct page 
 		res_counter_uncharge(&to->res, PAGE_SIZE);
 	}
 out:
-	unlock_page_cgroup(page);
+	unlock_page_cgroup(pc);
 
 	return ret;
 }
@@ -651,26 +545,27 @@ static int mem_cgroup_charge_common(stru
 {
 	struct mem_cgroup *mem;
 	struct page_cgroup *pc;
-	unsigned long flags;
 	unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
 	struct mem_cgroup_per_zone *mz;
+	unsigned long flags;
 
-	pc = kmem_cache_alloc(page_cgroup_cache, gfp_mask);
-	if (unlikely(pc == NULL))
-		goto err;
-
+	pc = lookup_page_cgroup(page);
+	/* can happen at boot */
+	if (unlikely(!pc))
+		return 0;
+	prefetchw(pc);
 	/*
 	 * We always charge the cgroup the mm_struct belongs to.
 	 * The mm_struct's mem_cgroup changes on task migration if the
 	 * thread group leader migrates. It's possible that mm is not
 	 * set, if so charge the init_mm (happens for pagecache usage).
 	 */
+
 	if (likely(!memcg)) {
 		rcu_read_lock();
 		mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
 		if (unlikely(!mem)) {
 			rcu_read_unlock();
-			kmem_cache_free(page_cgroup_cache, pc);
 			return 0;
 		}
 		/*
@@ -706,36 +601,34 @@ static int mem_cgroup_charge_common(stru
 		}
 	}
 
+	preempt_disable();
+	lock_page_cgroup(pc);
+	if (unlikely(PageCgroupUsed(pc))) {
+		unlock_page_cgroup(pc);
+		res_counter_uncharge(&mem->res, PAGE_SIZE);
+		css_put(&mem->css);
+		preempt_enable();
+		goto done;
+	}
 	pc->mem_cgroup = mem;
-	pc->page = page;
 	/*
 	 * If a page is accounted as a page cache, insert to inactive list.
 	 * If anon, insert to active list.
 	 */
 	pc->flags = pcg_default_flags[ctype];
 
-	lock_page_cgroup(page);
-	if (unlikely(page_get_page_cgroup(page))) {
-		unlock_page_cgroup(page);
-		res_counter_uncharge(&mem->res, PAGE_SIZE);
-		css_put(&mem->css);
-		kmem_cache_free(page_cgroup_cache, pc);
-		goto done;
-	}
-	page_assign_page_cgroup(page, pc);
-
 	mz = page_cgroup_zoneinfo(pc);
+
 	spin_lock_irqsave(&mz->lru_lock, flags);
 	__mem_cgroup_add_list(mz, pc);
 	spin_unlock_irqrestore(&mz->lru_lock, flags);
+	unlock_page_cgroup(pc);
+	preempt_enable();
 
-	unlock_page_cgroup(page);
 done:
 	return 0;
 out:
 	css_put(&mem->css);
-	kmem_cache_free(page_cgroup_cache, pc);
-err:
 	return -ENOMEM;
 }
 
@@ -743,7 +636,8 @@ int mem_cgroup_charge(struct page *page,
 {
 	if (mem_cgroup_subsys.disabled)
 		return 0;
-
+	if (PageCompound(page))
+		return 0;
 	/*
 	 * If already mapped, we don't have to account.
 	 * If page cache, page->mapping has address_space.
@@ -764,7 +658,8 @@ int mem_cgroup_cache_charge(struct page 
 {
 	if (mem_cgroup_subsys.disabled)
 		return 0;
-
+	if (PageCompound(page))
+		return 0;
 	/*
 	 * Corner case handling. This is called from add_to_page_cache()
 	 * in usual. But some FS (shmem) precharges this page before calling it
@@ -777,15 +672,16 @@ int mem_cgroup_cache_charge(struct page 
 	if (!(gfp_mask & __GFP_WAIT)) {
 		struct page_cgroup *pc;
 
-		lock_page_cgroup(page);
-		pc = page_get_page_cgroup(page);
-		if (pc) {
-			VM_BUG_ON(pc->page != page);
-			VM_BUG_ON(!pc->mem_cgroup);
-			unlock_page_cgroup(page);
+
+		pc = lookup_page_cgroup(page);
+		if (!pc)
+			return 0;
+		lock_page_cgroup(pc);
+		if (PageCgroupUsed(pc)) {
+			unlock_page_cgroup(pc);
 			return 0;
 		}
-		unlock_page_cgroup(page);
+		unlock_page_cgroup(pc);
 	}
 
 	if (unlikely(!mm))
@@ -812,49 +708,41 @@ __mem_cgroup_uncharge_common(struct page
 
 	if (mem_cgroup_subsys.disabled)
 		return;
+	/* check the condition we can know from page */
 
-	/*
-	 * Check if our page_cgroup is valid
-	 */
-	lock_page_cgroup(page);
-	pc = page_get_page_cgroup(page);
-	if (unlikely(!pc))
-		goto unlock;
-
-	VM_BUG_ON(pc->page != page);
+	pc = lookup_page_cgroup(page);
+	if (unlikely(!pc || !PageCgroupUsed(pc)))
+		return;
+	preempt_disable();
+	lock_page_cgroup(pc);
+	if (unlikely(page_mapped(page))) {
+		unlock_page_cgroup(pc);
+		preempt_enable();
+		return;
+	}
+	ClearPageCgroupUsed(pc);
+	unlock_page_cgroup(pc);
 
-	if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
-	    && ((PageCgroupCache(pc) || page_mapped(page))))
-		goto unlock;
-retry:
 	mem = pc->mem_cgroup;
 	mz = page_cgroup_zoneinfo(pc);
+
 	spin_lock_irqsave(&mz->lru_lock, flags);
-	if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED &&
-	    unlikely(mem != pc->mem_cgroup)) {
-		/* MAPPED account can be done without lock_page().
-		   Check race with mem_cgroup_move_account() */
-		spin_unlock_irqrestore(&mz->lru_lock, flags);
-		goto retry;
-	}
 	__mem_cgroup_remove_list(mz, pc);
 	spin_unlock_irqrestore(&mz->lru_lock, flags);
-
-	page_assign_page_cgroup(page, NULL);
-	unlock_page_cgroup(page);
-
-
-	res_counter_uncharge(&mem->res, PAGE_SIZE);
+	pc->mem_cgroup = NULL;
 	css_put(&mem->css);
+	preempt_enable();
+	res_counter_uncharge(&mem->res, PAGE_SIZE);
 
-	kmem_cache_free(page_cgroup_cache, pc);
 	return;
-unlock:
-	unlock_page_cgroup(page);
 }
 
 void mem_cgroup_uncharge_page(struct page *page)
 {
+	if (page_mapped(page))
+		return;
+	if (page->mapping && !PageAnon(page))
+		return;
 	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
 }
 
@@ -878,9 +766,9 @@ int mem_cgroup_prepare_migration(struct 
 	if (mem_cgroup_subsys.disabled)
 		return 0;
 
-	lock_page_cgroup(page);
-	pc = page_get_page_cgroup(page);
-	if (pc) {
+	pc = lookup_page_cgroup(page);
+	lock_page_cgroup(pc);
+	if (PageCgroupUsed(pc)) {
 		mem = pc->mem_cgroup;
 		css_get(&mem->css);
 		if (PageCgroupCache(pc)) {
@@ -890,7 +778,7 @@ int mem_cgroup_prepare_migration(struct 
 				ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
 		}
 	}
-	unlock_page_cgroup(page);
+	unlock_page_cgroup(pc);
 	if (mem) {
 		ret = mem_cgroup_charge_common(newpage, NULL, GFP_KERNEL,
 			ctype, mem);
@@ -997,6 +885,8 @@ static void mem_cgroup_force_empty_list(
 	spin_lock_irqsave(&mz->lru_lock, flags);
 	list_for_each_entry_safe(pc, tmp, list, lru) {
 		page = pc->page;
+		if (!PageCgroupUsed(pc))
+			continue;
 		/* For avoiding race with speculative page cache handling. */
 		if (!PageLRU(page) || !get_page_unless_zero(page)) {
 			continue;
@@ -1270,8 +1160,8 @@ mem_cgroup_create(struct cgroup_subsys *
 	int node;
 
 	if (unlikely((cont->parent) == NULL)) {
+		page_cgroup_init();
 		mem = &init_mem_cgroup;
-		page_cgroup_cache = KMEM_CACHE(page_cgroup, SLAB_PANIC);
 	} else {
 		mem = mem_cgroup_alloc();
 		if (!mem)
Index: mmotm-2.6.27-rc7+/mm/page_alloc.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/page_alloc.c
+++ mmotm-2.6.27-rc7+/mm/page_alloc.c
@@ -44,7 +44,7 @@
 #include <linux/backing-dev.h>
 #include <linux/fault-inject.h>
 #include <linux/page-isolation.h>
-#include <linux/memcontrol.h>
+#include <linux/page_cgroup.h>
 #include <linux/debugobjects.h>
 
 #include <asm/tlbflush.h>
@@ -223,17 +223,12 @@ static inline int bad_range(struct zone 
 
 static void bad_page(struct page *page)
 {
-	void *pc = page_get_page_cgroup(page);
-
 	printk(KERN_EMERG "Bad page state in process '%s'\n" KERN_EMERG
 		"page:%p flags:0x%0*lx mapping:%p mapcount:%d count:%d\n",
 		current->comm, page, (int)(2*sizeof(unsigned long)),
 		(unsigned long)page->flags, page->mapping,
 		page_mapcount(page), page_count(page));
-	if (pc) {
-		printk(KERN_EMERG "cgroup:%p\n", pc);
-		page_reset_bad_cgroup(page);
-	}
+
 	printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n"
 		KERN_EMERG "Backtrace:\n");
 	dump_stack();
@@ -472,7 +467,6 @@ static inline void free_pages_check(stru
 	free_page_mlock(page);
 	if (unlikely(page_mapcount(page) |
 		(page->mapping != NULL)  |
-		(page_get_page_cgroup(page) != NULL) |
 		(page_count(page) != 0)  |
 		(page->flags & PAGE_FLAGS_CHECK_AT_FREE)))
 		bad_page(page);
@@ -609,7 +603,6 @@ static void prep_new_page(struct page *p
 {
 	if (unlikely(page_mapcount(page) |
 		(page->mapping != NULL)  |
-		(page_get_page_cgroup(page) != NULL) |
 		(page_count(page) != 0)  |
 		(page->flags & PAGE_FLAGS_CHECK_AT_PREP)))
 		bad_page(page);
@@ -3495,6 +3488,7 @@ static void __paginginit free_area_init_
 	pgdat->nr_zones = 0;
 	init_waitqueue_head(&pgdat->kswapd_wait);
 	pgdat->kswapd_max_order = 0;
+	pgdat_page_cgroup_init(pgdat);
 	
 	for (j = 0; j < MAX_NR_ZONES; j++) {
 		struct zone *zone = pgdat->node_zones + j;
Index: mmotm-2.6.27-rc7+/include/linux/mmzone.h
===================================================================
--- mmotm-2.6.27-rc7+.orig/include/linux/mmzone.h
+++ mmotm-2.6.27-rc7+/include/linux/mmzone.h
@@ -604,6 +604,9 @@ typedef struct pglist_data {
 	int nr_zones;
 #ifdef CONFIG_FLAT_NODE_MEM_MAP
 	struct page *node_mem_map;
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+	struct page_cgroup *node_page_cgroup;
+#endif
 #endif
 	struct bootmem_data *bdata;
 #ifdef CONFIG_MEMORY_HOTPLUG
@@ -932,6 +935,7 @@ static inline unsigned long early_pfn_to
 #endif
 
 struct page;
+struct page_cgroup;
 struct mem_section {
 	/*
 	 * This is, logically, a pointer to an array of struct
@@ -949,6 +953,11 @@ struct mem_section {
 
 	/* See declaration of similar field in struct zone */
 	unsigned long *pageblock_flags;
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+	/* see page_cgroup.h */
+	struct page_cgroup *page_cgroup;
+	unsigned long pad;
+#endif
 };
 
 #ifdef CONFIG_SPARSEMEM_EXTREME
Index: mmotm-2.6.27-rc7+/include/linux/memcontrol.h
===================================================================
--- mmotm-2.6.27-rc7+.orig/include/linux/memcontrol.h
+++ mmotm-2.6.27-rc7+/include/linux/memcontrol.h
@@ -29,7 +29,6 @@ struct mm_struct;
 
 #define page_reset_bad_cgroup(page)	((page)->page_cgroup = 0)
 
-extern struct page_cgroup *page_get_page_cgroup(struct page *page);
 extern int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
 				gfp_t gfp_mask);
 extern int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
@@ -72,16 +71,8 @@ extern void mem_cgroup_record_reclaim_pr
 extern long mem_cgroup_calc_reclaim(struct mem_cgroup *mem, struct zone *zone,
 					int priority, enum lru_list lru);
 
-#else /* CONFIG_CGROUP_MEM_RES_CTLR */
-static inline void page_reset_bad_cgroup(struct page *page)
-{
-}
-
-static inline struct page_cgroup *page_get_page_cgroup(struct page *page)
-{
-	return NULL;
-}
 
+#else /* CONFIG_CGROUP_MEM_RES_CTLR */
 static inline int mem_cgroup_charge(struct page *page,
 					struct mm_struct *mm, gfp_t gfp_mask)
 {

Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[Dave Hansen]

On Thu, 2008-09-25 at 15:32 +0900, KAMEZAWA Hiroyuki wrote:
> @@ -949,6 +953,11 @@ struct mem_section {
> 
>         /* See declaration of similar field in struct zone */
>         unsigned long *pageblock_flags;
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR
> +       /* see page_cgroup.h */
> +       struct page_cgroup *page_cgroup;
> +       unsigned long pad;
> +#endif
>  };

I thought the use of this variable was under the

	+#ifdef CONFIG_FLAT_NODE_MEM_MAP

options.  Otherwise, we unconditionally bloat mem_section, right?

-- Dave

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[KAMEZAWA Hiroyuki]

On Thu, 25 Sep 2008 11:40:47 -0700
Dave Hansen <dave@linux.vnet.ibm.com> wrote:

> On Thu, 2008-09-25 at 15:32 +0900, KAMEZAWA Hiroyuki wrote:
> > @@ -949,6 +953,11 @@ struct mem_section {
> > 
> >         /* See declaration of similar field in struct zone */
> >         unsigned long *pageblock_flags;
> > +#ifdef CONFIG_CGROUP_MEM_RES_CTLR
> > +       /* see page_cgroup.h */
> > +       struct page_cgroup *page_cgroup;
> > +       unsigned long pad;
> > +#endif
> >  };
> 
> I thought the use of this variable was under the
> 
> 	+#ifdef CONFIG_FLAT_NODE_MEM_MAP
> 
> options.  Otherwise, we unconditionally bloat mem_section, right?
> 
Hmmm......Oh, yes ! nice catch.

Thanks, I'll fix.
-Kame

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 10:17:54 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> On Thu, 25 Sep 2008 11:40:47 -0700
> Dave Hansen <dave@linux.vnet.ibm.com> wrote:
> 
> > On Thu, 2008-09-25 at 15:32 +0900, KAMEZAWA Hiroyuki wrote:
> > > @@ -949,6 +953,11 @@ struct mem_section {
> > > 
> > >         /* See declaration of similar field in struct zone */
> > >         unsigned long *pageblock_flags;
> > > +#ifdef CONFIG_CGROUP_MEM_RES_CTLR
> > > +       /* see page_cgroup.h */
> > > +       struct page_cgroup *page_cgroup;
> > > +       unsigned long pad;
> > > +#endif
> > >  };
> > 
> > I thought the use of this variable was under the
> > 
> > 	+#ifdef CONFIG_FLAT_NODE_MEM_MAP
> > 
> > options.  Otherwise, we unconditionally bloat mem_section, right?
> > 
> Hmmm......Oh, yes ! nice catch.
> 
> Thanks, I'll fix.

But in reality, this is under CONFIG_SPARSEMEM and if CONFIG_SPARSEMEM,
FLAT_NODE_MEM_MAP is not true (I think).
Hmm..Maybe I shouldn't use checking CONFIG_FLAT_NODE_MEM_MAP and should
just use CONFIG_SPARSEMEM check. I'll rewrite.

Thanks,
-Kame

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[Daisuke Nishimura]

On Thu, 25 Sep 2008 15:32:06 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> Allocate all page_cgroup at boot and remove page_cgroup poitner
> from struct page. This patch adds an interface as
> 
>  struct page_cgroup *lookup_page_cgroup(struct page*)
> 
> All FLATMEM/DISCONTIGMEM/SPARSEMEM  and MEMORY_HOTPLUG is supported.
> 
> Remove page_cgroup pointer reduces the amount of memory by
>  - 4 bytes per PAGE_SIZE.
>  - 8 bytes per PAGE_SIZE
> if memory controller is disabled. (even if configured.)
> meta data usage of this is no problem in FLATMEM/DISCONTIGMEM.
> On SPARSEMEM, this makes mem_section[] size twice.
> 
> On usual 8GB x86-32 server, this saves 8MB of NORMAL_ZONE memory.
> On my x86-64 server with 48GB of memory, this saves 96MB of memory.
> (and uses xx kbytes for mem_section.)
> I think this reduction makes sense.
> 
> By pre-allocation, kmalloc/kfree in charge/uncharge are removed. 
> This means
>   - we're not necessary to be afraid of kmalloc faiulre.
>     (this can happen because of gfp_mask type.)
>   - we can avoid calling kmalloc/kfree.
>   - we can avoid allocating tons of small objects which can be fragmented.
>   - we can know what amount of memory will be used for this extra-lru handling.
> 
> I added printk message as
> 
> 	"allocated %ld bytes of page_cgroup"
>         "please try cgroup_disable=memory option if you don't want"
> 
> maybe enough informative for users.
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
>  include/linux/memcontrol.h  |   11 -
>  include/linux/mm_types.h    |    4 
>  include/linux/mmzone.h      |    9 +
>  include/linux/page_cgroup.h |   90 +++++++++++++++
>  mm/Makefile                 |    2 
>  mm/memcontrol.c             |  258 ++++++++++++--------------------------------
>  mm/page_alloc.c             |   12 --
>  mm/page_cgroup.c            |  253 +++++++++++++++++++++++++++++++++++++++++++
>  8 files changed, 431 insertions(+), 208 deletions(-)
> 
> Index: mmotm-2.6.27-rc7+/mm/page_cgroup.c
> ===================================================================
> --- /dev/null
> +++ mmotm-2.6.27-rc7+/mm/page_cgroup.c
> @@ -0,0 +1,253 @@
> +#include <linux/mm.h>
> +#include <linux/mmzone.h>
> +#include <linux/bootmem.h>
> +#include <linux/bit_spinlock.h>
> +#include <linux/page_cgroup.h>
> +#include <linux/hash.h>
> +#include <linux/memory.h>
> +
> +static void __meminit
> +__init_page_cgroup(struct page_cgroup *pc, unsigned long pfn)
> +{
> +	pc->flags = 0;
> +	pc->mem_cgroup = NULL;
> +	pc->page = pfn_to_page(pfn);
> +}
> +static unsigned long total_usage = 0;
> +
> +#ifdef CONFIG_FLAT_NODE_MEM_MAP
> +
> +
> +void __init pgdat_page_cgroup_init(struct pglist_data *pgdat)
> +{
> +	pgdat->node_page_cgroup = NULL;
> +}
> +
> +struct page_cgroup *lookup_page_cgroup(struct page *page)
> +{
> +	unsigned long pfn = page_to_pfn(page);
> +	unsigned long offset;
> +	struct page_cgroup *base;
> +
> +	base = NODE_DATA(page_to_nid(nid))->node_page_cgroup;
page_to_nid(page) :)

> +	if (unlikely(!base))
> +		return NULL;
> +
> +	offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
> +	return base + offset;
> +}
> +
> +static int __init alloc_node_page_cgroup(int nid)
> +{
> +	struct page_cgroup *base, *pc;
> +	unsigned long table_size;
> +	unsigned long start_pfn, nr_pages, index;
> +
> +	start_pfn = NODE_DATA(nid)->node_start_pfn;
> +	nr_pages = NODE_DATA(nid)->node_spanned_pages;
> +
> +	table_size = sizeof(struct page_cgroup) * nr_pages;
> +
> +	base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
> +			table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
> +	if (!base)
> +		return -ENOMEM;
> +	for (index = 0; index < nr_pages; index++) {
> +		pc = base + index;
> +		__init_page_cgroup(pc, start_pfn + index);
> +	}
> +	NODE_DATA(nid)->node_page_cgroup = base;
> +	total_usage += table_size;
> +	return 0;
> +}
> +
> +void __init free_node_page_cgroup(int nid)
> +{
> +	unsigned long table_size;
> +	unsigned long nr_pages;
> +	struct page_cgroup *base;
> +
> +	base = NODE_DATA(nid)->node_page_cgroup;
> +	if (!base)
> +		return;
> +	nr_pages = NODE_DATA(nid)->node_spanned_pages;
> +
> +	table_size = sizeof(struct page_cgroup) * nr_pages;
> +
> +	free_bootmem_node(NODE_DATA(nid),
> +			(unsigned long)base, table_size);
> +	NODE_DATA(nid)->node_page_cgroup = NULL;
> +}
> +
Hmm, who uses this function?

(snip)

> @@ -812,49 +708,41 @@ __mem_cgroup_uncharge_common(struct page
>  
>  	if (mem_cgroup_subsys.disabled)
>  		return;
> +	/* check the condition we can know from page */
>  
> -	/*
> -	 * Check if our page_cgroup is valid
> -	 */
> -	lock_page_cgroup(page);
> -	pc = page_get_page_cgroup(page);
> -	if (unlikely(!pc))
> -		goto unlock;
> -
> -	VM_BUG_ON(pc->page != page);
> +	pc = lookup_page_cgroup(page);
> +	if (unlikely(!pc || !PageCgroupUsed(pc)))
> +		return;
> +	preempt_disable();
> +	lock_page_cgroup(pc);
> +	if (unlikely(page_mapped(page))) {
> +		unlock_page_cgroup(pc);
> +		preempt_enable();
> +		return;
> +	}
Just for clarification, in what sequence will the page be mapped here?
mem_cgroup_uncharge_page checks whether the page is mapped.

> +	ClearPageCgroupUsed(pc);
> +	unlock_page_cgroup(pc);
>  
> -	if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
> -	    && ((PageCgroupCache(pc) || page_mapped(page))))
> -		goto unlock;
> -retry:
>  	mem = pc->mem_cgroup;
>  	mz = page_cgroup_zoneinfo(pc);
> +
>  	spin_lock_irqsave(&mz->lru_lock, flags);
> -	if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED &&
> -	    unlikely(mem != pc->mem_cgroup)) {
> -		/* MAPPED account can be done without lock_page().
> -		   Check race with mem_cgroup_move_account() */
> -		spin_unlock_irqrestore(&mz->lru_lock, flags);
> -		goto retry;
> -	}
By these changes, ctype becomes unnecessary so it can be removed.

>  	__mem_cgroup_remove_list(mz, pc);
>  	spin_unlock_irqrestore(&mz->lru_lock, flags);
> -
> -	page_assign_page_cgroup(page, NULL);
> -	unlock_page_cgroup(page);
> -
> -
> -	res_counter_uncharge(&mem->res, PAGE_SIZE);
> +	pc->mem_cgroup = NULL;
>  	css_put(&mem->css);
> +	preempt_enable();
> +	res_counter_uncharge(&mem->res, PAGE_SIZE);
>  
> -	kmem_cache_free(page_cgroup_cache, pc);
>  	return;
> -unlock:
> -	unlock_page_cgroup(page);
>  }
>  


Thanks,
Daisuke Nishimura.

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 10:00:22 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> On Thu, 25 Sep 2008 15:32:06 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > Allocate all page_cgroup at boot and remove page_cgroup poitner
> > from struct page. This patch adds an interface as
> > 
> >  struct page_cgroup *lookup_page_cgroup(struct page*)
> > 
> > All FLATMEM/DISCONTIGMEM/SPARSEMEM  and MEMORY_HOTPLUG is supported.
> > 
> > Remove page_cgroup pointer reduces the amount of memory by
> >  - 4 bytes per PAGE_SIZE.
> >  - 8 bytes per PAGE_SIZE
> > if memory controller is disabled. (even if configured.)
> > meta data usage of this is no problem in FLATMEM/DISCONTIGMEM.
> > On SPARSEMEM, this makes mem_section[] size twice.
> > 
> > On usual 8GB x86-32 server, this saves 8MB of NORMAL_ZONE memory.
> > On my x86-64 server with 48GB of memory, this saves 96MB of memory.
> > (and uses xx kbytes for mem_section.)
> > I think this reduction makes sense.
> > 
> > By pre-allocation, kmalloc/kfree in charge/uncharge are removed. 
> > This means
> >   - we're not necessary to be afraid of kmalloc faiulre.
> >     (this can happen because of gfp_mask type.)
> >   - we can avoid calling kmalloc/kfree.
> >   - we can avoid allocating tons of small objects which can be fragmented.
> >   - we can know what amount of memory will be used for this extra-lru handling.
> > 
> > I added printk message as
> > 
> > 	"allocated %ld bytes of page_cgroup"
> >         "please try cgroup_disable=memory option if you don't want"
> > 
> > maybe enough informative for users.
> > 
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> > 
> >  include/linux/memcontrol.h  |   11 -
> >  include/linux/mm_types.h    |    4 
> >  include/linux/mmzone.h      |    9 +
> >  include/linux/page_cgroup.h |   90 +++++++++++++++
> >  mm/Makefile                 |    2 
> >  mm/memcontrol.c             |  258 ++++++++++++--------------------------------
> >  mm/page_alloc.c             |   12 --
> >  mm/page_cgroup.c            |  253 +++++++++++++++++++++++++++++++++++++++++++
> >  8 files changed, 431 insertions(+), 208 deletions(-)
> > 
> > Index: mmotm-2.6.27-rc7+/mm/page_cgroup.c
> > ===================================================================
> > --- /dev/null
> > +++ mmotm-2.6.27-rc7+/mm/page_cgroup.c
> > @@ -0,0 +1,253 @@
> > +#include <linux/mm.h>
> > +#include <linux/mmzone.h>
> > +#include <linux/bootmem.h>
> > +#include <linux/bit_spinlock.h>
> > +#include <linux/page_cgroup.h>
> > +#include <linux/hash.h>
> > +#include <linux/memory.h>
> > +
> > +static void __meminit
> > +__init_page_cgroup(struct page_cgroup *pc, unsigned long pfn)
> > +{
> > +	pc->flags = 0;
> > +	pc->mem_cgroup = NULL;
> > +	pc->page = pfn_to_page(pfn);
> > +}
> > +static unsigned long total_usage = 0;
> > +
> > +#ifdef CONFIG_FLAT_NODE_MEM_MAP
> > +
> > +
> > +void __init pgdat_page_cgroup_init(struct pglist_data *pgdat)
> > +{
> > +	pgdat->node_page_cgroup = NULL;
> > +}
> > +
> > +struct page_cgroup *lookup_page_cgroup(struct page *page)
> > +{
> > +	unsigned long pfn = page_to_pfn(page);
> > +	unsigned long offset;
> > +	struct page_cgroup *base;
> > +
> > +	base = NODE_DATA(page_to_nid(nid))->node_page_cgroup;
> page_to_nid(page) :)
> 
yes..

> > +	if (unlikely(!base))
> > +		return NULL;
> > +
> > +	offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
> > +	return base + offset;
> > +}
> > +
> > +static int __init alloc_node_page_cgroup(int nid)
> > +{
> > +	struct page_cgroup *base, *pc;
> > +	unsigned long table_size;
> > +	unsigned long start_pfn, nr_pages, index;
> > +
> > +	start_pfn = NODE_DATA(nid)->node_start_pfn;
> > +	nr_pages = NODE_DATA(nid)->node_spanned_pages;
> > +
> > +	table_size = sizeof(struct page_cgroup) * nr_pages;
> > +
> > +	base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
> > +			table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
> > +	if (!base)
> > +		return -ENOMEM;
> > +	for (index = 0; index < nr_pages; index++) {
> > +		pc = base + index;
> > +		__init_page_cgroup(pc, start_pfn + index);
> > +	}
> > +	NODE_DATA(nid)->node_page_cgroup = base;
> > +	total_usage += table_size;
> > +	return 0;
> > +}
> > +
> > +void __init free_node_page_cgroup(int nid)
> > +{
> > +	unsigned long table_size;
> > +	unsigned long nr_pages;
> > +	struct page_cgroup *base;
> > +
> > +	base = NODE_DATA(nid)->node_page_cgroup;
> > +	if (!base)
> > +		return;
> > +	nr_pages = NODE_DATA(nid)->node_spanned_pages;
> > +
> > +	table_size = sizeof(struct page_cgroup) * nr_pages;
> > +
> > +	free_bootmem_node(NODE_DATA(nid),
> > +			(unsigned long)base, table_size);
> > +	NODE_DATA(nid)->node_page_cgroup = NULL;
> > +}
> > +
> Hmm, who uses this function?
> 
Uh, ok. unnecessary. (In my first version, this allocation error
just shows Warning. Now, it panics.)

Appearently, FLATMEM check is not enough...

> (snip)
> 
> > @@ -812,49 +708,41 @@ __mem_cgroup_uncharge_common(struct page
> >  
> >  	if (mem_cgroup_subsys.disabled)
> >  		return;
> > +	/* check the condition we can know from page */
> >  
> > -	/*
> > -	 * Check if our page_cgroup is valid
> > -	 */
> > -	lock_page_cgroup(page);
> > -	pc = page_get_page_cgroup(page);
> > -	if (unlikely(!pc))
> > -		goto unlock;
> > -
> > -	VM_BUG_ON(pc->page != page);
> > +	pc = lookup_page_cgroup(page);
> > +	if (unlikely(!pc || !PageCgroupUsed(pc)))
> > +		return;
> > +	preempt_disable();
> > +	lock_page_cgroup(pc);
> > +	if (unlikely(page_mapped(page))) {
> > +		unlock_page_cgroup(pc);
> > +		preempt_enable();
> > +		return;
> > +	}
> Just for clarification, in what sequence will the page be mapped here?
> mem_cgroup_uncharge_page checks whether the page is mapped.
> 
Please think about folloing situation.

   There is a SwapCache which is referred from 2 process, A, B.
   A maps it.
   B doesn't maps it.

   And now, process A exits.

	CPU0(process A)				CPU1 (process B)
 
    zap_pte_range()
    => page remove from rmap			=> charge() (do_swap_page)
	=> set page->mapcount->0          	
		=> uncharge()			=> set page->mapcount=1

This race is what patch 12/12 is fixed.
This only happens on cursed SwapCache.


> > +	ClearPageCgroupUsed(pc);
> > +	unlock_page_cgroup(pc);
> >  
> > -	if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
> > -	    && ((PageCgroupCache(pc) || page_mapped(page))))
> > -		goto unlock;
> > -retry:
> >  	mem = pc->mem_cgroup;
> >  	mz = page_cgroup_zoneinfo(pc);
> > +
> >  	spin_lock_irqsave(&mz->lru_lock, flags);
> > -	if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED &&
> > -	    unlikely(mem != pc->mem_cgroup)) {
> > -		/* MAPPED account can be done without lock_page().
> > -		   Check race with mem_cgroup_move_account() */
> > -		spin_unlock_irqrestore(&mz->lru_lock, flags);
> > -		goto retry;
> > -	}
> By these changes, ctype becomes unnecessary so it can be removed.
> 
Uh, maybe it can be removed.

> >  	__mem_cgroup_remove_list(mz, pc);
> >  	spin_unlock_irqrestore(&mz->lru_lock, flags);
> > -
> > -	page_assign_page_cgroup(page, NULL);
> > -	unlock_page_cgroup(page);
> > -
> > -
> > -	res_counter_uncharge(&mem->res, PAGE_SIZE);
> > +	pc->mem_cgroup = NULL;
> >  	css_put(&mem->css);
> > +	preempt_enable();
> > +	res_counter_uncharge(&mem->res, PAGE_SIZE);
> >  
> > -	kmem_cache_free(page_cgroup_cache, pc);
> >  	return;
> > -unlock:
> > -	unlock_page_cgroup(page);
> >  }
> >  

Thank you for review.

Regards,
-Kame

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 10:43:36 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > > -	/*
> > > -	 * Check if our page_cgroup is valid
> > > -	 */
> > > -	lock_page_cgroup(page);
> > > -	pc = page_get_page_cgroup(page);
> > > -	if (unlikely(!pc))
> > > -		goto unlock;
> > > -
> > > -	VM_BUG_ON(pc->page != page);
> > > +	pc = lookup_page_cgroup(page);
> > > +	if (unlikely(!pc || !PageCgroupUsed(pc)))
> > > +		return;
> > > +	preempt_disable();
> > > +	lock_page_cgroup(pc);
> > > +	if (unlikely(page_mapped(page))) {
> > > +		unlock_page_cgroup(pc);
> > > +		preempt_enable();
> > > +		return;
> > > +	}
> > Just for clarification, in what sequence will the page be mapped here?
> > mem_cgroup_uncharge_page checks whether the page is mapped.
> > 
> Please think about folloing situation.
> 
>    There is a SwapCache which is referred from 2 process, A, B.
>    A maps it.
>    B doesn't maps it.
> 
>    And now, process A exits.
> 
> 	CPU0(process A)				CPU1 (process B)
>  
>     zap_pte_range()
>     => page remove from rmap			=> charge() (do_swap_page)
> 	=> set page->mapcount->0          	
> 		=> uncharge()			=> set page->mapcount=1
> 
> This race is what patch 12/12 is fixed.
> This only happens on cursed SwapCache.
> 
Sorry, my brain seems to be sleeping.. above page_mapped() check doesn't
help this situation. Maybe this page_mapped() check is not necessary
because it's of no use.

I think this kind of problem will not be fixed until we handle SwapCache.


Thanks,
-Kame












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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[Daisuke Nishimura]

On Fri, 26 Sep 2008 11:05:50 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> On Fri, 26 Sep 2008 10:43:36 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > > > -	/*
> > > > -	 * Check if our page_cgroup is valid
> > > > -	 */
> > > > -	lock_page_cgroup(page);
> > > > -	pc = page_get_page_cgroup(page);
> > > > -	if (unlikely(!pc))
> > > > -		goto unlock;
> > > > -
> > > > -	VM_BUG_ON(pc->page != page);
> > > > +	pc = lookup_page_cgroup(page);
> > > > +	if (unlikely(!pc || !PageCgroupUsed(pc)))
> > > > +		return;
> > > > +	preempt_disable();
> > > > +	lock_page_cgroup(pc);
> > > > +	if (unlikely(page_mapped(page))) {
> > > > +		unlock_page_cgroup(pc);
> > > > +		preempt_enable();
> > > > +		return;
> > > > +	}
> > > Just for clarification, in what sequence will the page be mapped here?
> > > mem_cgroup_uncharge_page checks whether the page is mapped.
> > > 
> > Please think about folloing situation.
> > 
> >    There is a SwapCache which is referred from 2 process, A, B.
> >    A maps it.
> >    B doesn't maps it.
> > 
> >    And now, process A exits.
> > 
> > 	CPU0(process A)				CPU1 (process B)
> >  
> >     zap_pte_range()
> >     => page remove from rmap			=> charge() (do_swap_page)
> > 	=> set page->mapcount->0          	
> > 		=> uncharge()			=> set page->mapcount=1
> > 
> > This race is what patch 12/12 is fixed.
> > This only happens on cursed SwapCache.
> > 
> Sorry, my brain seems to be sleeping.. above page_mapped() check doesn't
> help this situation. Maybe this page_mapped() check is not necessary
> because it's of no use.
> 
> I think this kind of problem will not be fixed until we handle SwapCache.
> 
I've not fully understood yet what [12/12] does, but if we handle
swapcache properly, [12/12] would become unnecessary?

If so, how about handling swapcache instead of adding new interface?
I think it can be done independent of mem+swap.


Thanks,
Daisuke Nishimura.

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 14:54:22 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> > >    There is a SwapCache which is referred from 2 process, A, B.
> > >    A maps it.
> > >    B doesn't maps it.
> > > 
> > >    And now, process A exits.
> > > 
> > > 	CPU0(process A)				CPU1 (process B)
> > >  
> > >     zap_pte_range()
> > >     => page remove from rmap			=> charge() (do_swap_page)
> > > 	=> set page->mapcount->0          	
> > > 		=> uncharge()			=> set page->mapcount=1
> > > 
> > > This race is what patch 12/12 is fixed.
> > > This only happens on cursed SwapCache.
> > > 
> > Sorry, my brain seems to be sleeping.. above page_mapped() check doesn't
> > help this situation. Maybe this page_mapped() check is not necessary
> > because it's of no use.
> > 
> > I think this kind of problem will not be fixed until we handle SwapCache.
> > 
> I've not fully understood yet what [12/12] does, but if we handle
> swapcache properly, [12/12] would become unnecessary?
> 
Maybe yes. we treat swapcache under lock_page().

> If so, how about handling swapcache instead of adding new interface?
> I think it can be done independent of mem+swap.
> 
Hmm, worth to be considered. But I'll reuse the interface itself for othres
(shmem, migrate, move_account etc)
But, in previous trial of SwapCache handling, we saw many troubles.
Then, I'd like to go carefully step by step to handle that.

Thanks,
-Kame

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 14:54:22 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> > Sorry, my brain seems to be sleeping.. above page_mapped() check doesn't
> > help this situation. Maybe this page_mapped() check is not necessary
> > because it's of no use.
> > 
> > I think this kind of problem will not be fixed until we handle SwapCache.
> > 
> I've not fully understood yet what [12/12] does, but if we handle
> swapcache properly, [12/12] would become unnecessary?
> 

Try to illustrate what is trouble more precisely.


in do_swap_page(), page is charged when SwapCache lookup ends.

Here, 
     - charged when page is not mapped.
     - not charged when page is mapped.
set_pte() etc...are done under appropriate lock.

On the other side, when a task exits, zap_pte_range() is called.
It calls page_remove_rmap(). 

Case A) Following is race.

            Thread A                     Thread B

     do_swap_page()                      zap_pte_range()
	(1)try charge (mapcount=1)
                                         (2) page_remove_rmap()
					     (3) uncharge page. 
	(4) map it


Then,
 at (1),  mapcount=1 and this page is not charged.
 at (2),  page_remove_rmap() is called and mapcount goes down to Zero.
          uncharge(3) is called.
 at (4),  at the end of do_swap_page(), page->mapcount=1 but not charged.

Case B) In another scenario.

            Thread A                     Thread B

     do_swap_page()                      zap_pte_range()
	(1)try charge (mapcount=1)
                                         (2) page_remove_rmap()
	(3) map it
                                         (4) uncharge is called.

In (4), uncharge is capped but mapcount can go up to 1.

protocol 12/12 is for case (A).
After 12/12, double-check page_mapped() under lock_page_cgroup() will be fix to
case (B).

Huu, I don't like swap-cache ;)
Anyway, we'll have to handle swap cache later.

Thanks,
-Kame






















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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 10:43:36 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> > > -	VM_BUG_ON(pc->page != page);
> > > +	pc = lookup_page_cgroup(page);
> > > +	if (unlikely(!pc || !PageCgroupUsed(pc)))
> > > +		return;
> > > +	preempt_disable();
> > > +	lock_page_cgroup(pc);
> > > +	if (unlikely(page_mapped(page))) {
> > > +		unlock_page_cgroup(pc);
> > > +		preempt_enable();
> > > +		return;
> > > +	}
> > Just for clarification, in what sequence will the page be mapped here?
> > mem_cgroup_uncharge_page checks whether the page is mapped.
> > 

I think I saw page_mapped() case (in your shmem/page test.)
I'll check what cause this if I have time.

Thanks,
-Kame

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[PATCH(fixed) 9/12] memcg allocate all page_cgroup at boot

[KAMEZAWA Hiroyuki]

Because of terrible compile error in FLATMEM/DISCONTIGMEM, I post
fixed version (and avoid patch bomb again.)
I post replacements for 9(fix), and 10,11,12 (adjustment for HUNK).

==
Allocate all page_cgroup at boot and remove page_cgroup poitner
from struct page. This patch adds an interface as

 struct page_cgroup *lookup_page_cgroup(struct page*)

All FLATMEM/DISCONTIGMEM/SPARSEMEM  and MEMORY_HOTPLUG is supported.

Remove page_cgroup pointer reduces the amount of memory by
 - 4 bytes per PAGE_SIZE.
 - 8 bytes per PAGE_SIZE
if memory controller is disabled. (even if configured.)

On usual 8GB x86-32 server, this saves 8MB of NORMAL_ZONE memory.
On my x86-64 server with 48GB of memory, this saves 96MB of memory.
I think this reduction makes sense.

By pre-allocation, kmalloc/kfree in charge/uncharge are removed. 
This means
  - we're not necessary to be afraid of kmalloc faiulre.
    (this can happen because of gfp_mask type.)
  - we can avoid calling kmalloc/kfree.
  - we can avoid allocating tons of small objects which can be fragmented.
  - we can know what amount of memory will be used for this extra-lru handling.

I added printk message as

	"allocated %ld bytes of page_cgroup"
        "please try cgroup_disable=memory option if you don't want"

maybe enough informative for users.

TODO:
  - small race window still remains in do_swap_page(). will be fixed by
    later patch in series.

Changelog: v5 -> v6.
 * removed "ctype" from uncharge.
 * improved comment to show FLAT_NODE_MEM_MAP == !SPARSEMEM
 * fixed errors in !SPARSEMEM codes
 * removed unused function in !SPARSEMEM codes.
(start from v5 because of series..)

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 include/linux/memcontrol.h  |   11 -
 include/linux/mm_types.h    |    4 
 include/linux/mmzone.h      |   14 ++
 include/linux/page_cgroup.h |   90 +++++++++++++++
 mm/Makefile                 |    2 
 mm/memcontrol.c             |  264 ++++++++++++--------------------------------
 mm/page_alloc.c             |   12 --
 mm/page_cgroup.c            |  235 +++++++++++++++++++++++++++++++++++++++
 8 files changed, 416 insertions(+), 216 deletions(-)

Index: mmotm-2.6.27-rc7+/mm/page_cgroup.c
===================================================================
--- /dev/null
+++ mmotm-2.6.27-rc7+/mm/page_cgroup.c
@@ -0,0 +1,235 @@
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/bootmem.h>
+#include <linux/bit_spinlock.h>
+#include <linux/page_cgroup.h>
+#include <linux/hash.h>
+#include <linux/memory.h>
+
+static void __meminit
+__init_page_cgroup(struct page_cgroup *pc, unsigned long pfn)
+{
+	pc->flags = 0;
+	pc->mem_cgroup = NULL;
+	pc->page = pfn_to_page(pfn);
+}
+static unsigned long total_usage = 0;
+
+#if !defined(CONFIG_SPARSEMEM)
+
+
+void __init pgdat_page_cgroup_init(struct pglist_data *pgdat)
+{
+	pgdat->node_page_cgroup = NULL;
+}
+
+struct page_cgroup *lookup_page_cgroup(struct page *page)
+{
+	unsigned long pfn = page_to_pfn(page);
+	unsigned long offset;
+	struct page_cgroup *base;
+
+	base = NODE_DATA(page_to_nid(page))->node_page_cgroup;
+	if (unlikely(!base))
+		return NULL;
+
+	offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
+	return base + offset;
+}
+
+static int __init alloc_node_page_cgroup(int nid)
+{
+	struct page_cgroup *base, *pc;
+	unsigned long table_size;
+	unsigned long start_pfn, nr_pages, index;
+
+	start_pfn = NODE_DATA(nid)->node_start_pfn;
+	nr_pages = NODE_DATA(nid)->node_spanned_pages;
+
+	table_size = sizeof(struct page_cgroup) * nr_pages;
+
+	base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
+			table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
+	if (!base)
+		return -ENOMEM;
+	for (index = 0; index < nr_pages; index++) {
+		pc = base + index;
+		__init_page_cgroup(pc, start_pfn + index);
+	}
+	NODE_DATA(nid)->node_page_cgroup = base;
+	total_usage += table_size;
+	return 0;
+}
+
+void __init page_cgroup_init(void)
+{
+
+	int nid, fail;
+
+	for_each_online_node(nid)  {
+		fail = alloc_node_page_cgroup(nid);
+		if (fail)
+			goto fail;
+	}
+	printk("allocated %ld bytes of page_cgroup\n", total_usage);
+	printk("please try cgroup_disable=memory option if you don't want\n");
+	return;
+fail:
+	printk("allocation of page_cgroup was failed.\n");
+	printk("please try cgroup_disable=memory boot option\n");
+	panic("Out of memory");
+}
+
+#else /* CONFIG_FLAT_NODE_MEM_MAP */
+
+struct page_cgroup *lookup_page_cgroup(struct page *page)
+{
+	unsigned long pfn = page_to_pfn(page);
+	struct mem_section *section = __pfn_to_section(pfn);
+
+	return section->page_cgroup + pfn;
+}
+
+int __meminit init_section_page_cgroup(unsigned long pfn)
+{
+	struct mem_section *section;
+	struct page_cgroup *base, *pc;
+	unsigned long table_size;
+	int nid, index;
+
+	section = __pfn_to_section(pfn);
+
+	if (section->page_cgroup)
+		return 0;
+
+	nid = page_to_nid(pfn_to_page(pfn));
+
+	table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
+	base = kmalloc_node(table_size, GFP_KERNEL, nid);
+	if (!base)
+		base = vmalloc_node(table_size, nid);
+
+	if (!base) {
+		printk("page cgroup allocation failure\n");
+		return -ENOMEM;
+	}
+
+	for (index = 0; index < PAGES_PER_SECTION; index++) {
+		pc = base + index;
+		__init_page_cgroup(pc, pfn + index);
+	}
+
+	section = __pfn_to_section(pfn);
+	section->page_cgroup = base - pfn;
+	total_usage += table_size;
+	return 0;
+}
+#ifdef CONFIG_MEMORY_HOTPLUG
+void __free_page_cgroup(unsigned long pfn)
+{
+	struct mem_section *ms;
+	struct page_cgroup *base;
+
+	ms = __pfn_to_section(pfn);
+	if (!ms || !ms->page_cgroup)
+		return;
+	base = ms->page_cgroup + pfn;
+	ms->page_cgroup = NULL;
+	if (is_vmalloc_addr(base))
+		vfree(base);
+	else
+		kfree(base);
+}
+
+int online_page_cgroup(unsigned long start_pfn,
+			unsigned long nr_pages,
+			int nid)
+{
+	unsigned long start, end, pfn;
+	int fail = 0;
+
+	start = start_pfn & (PAGES_PER_SECTION - 1);
+	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
+
+	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
+		if (!pfn_present(pfn))
+			continue;
+		fail = init_section_page_cgroup(pfn);
+	}
+	if (!fail)
+		return 0;
+
+	/* rollback */
+	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
+		__free_page_cgroup(pfn);
+
+	return -ENOMEM;
+}
+
+int offline_page_cgroup(unsigned long start_pfn,
+		unsigned long nr_pages, int nid)
+{
+	unsigned long start, end, pfn;
+
+	start = start_pfn & (PAGES_PER_SECTION - 1);
+	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
+
+	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
+                __free_page_cgroup(pfn);
+	return 0;
+
+}
+
+static int page_cgroup_callback(struct notifier_block *self,
+			       unsigned long action, void *arg)
+{
+	struct memory_notify *mn = arg;
+	int ret = 0;
+	switch (action) {
+	case MEM_GOING_ONLINE:
+		ret = online_page_cgroup(mn->start_pfn,
+				   mn->nr_pages, mn->status_change_nid);
+		break;
+	case MEM_CANCEL_ONLINE:
+	case MEM_OFFLINE:
+		offline_page_cgroup(mn->start_pfn,
+				mn->nr_pages, mn->status_change_nid);
+		break;
+	case MEM_GOING_OFFLINE:
+		break;
+        case MEM_ONLINE:
+	case MEM_CANCEL_OFFLINE:
+		break;
+	}
+	ret = notifier_from_errno(ret);
+	return ret;
+}
+
+#endif
+
+void __init page_cgroup_init(void)
+{
+	unsigned long pfn;
+	int fail = 0;
+
+	for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) {
+		if (!pfn_present(pfn))
+			continue;
+		fail = init_section_page_cgroup(pfn);
+	}
+	if (fail) {
+		printk("please try cgroup_disable=memory boot option\n");
+		panic("Out of memory");
+	} else {
+		hotplug_memory_notifier(page_cgroup_callback, 0);
+	}
+	printk("allocated %ld bytes of page_cgroup\n", total_usage);
+	printk("please try cgroup_disable=memory option if you don't want\n");
+}
+
+void __init pgdat_page_cgroup_init(struct pglist_data *pgdat)
+{
+	return;
+}
+
+#endif
Index: mmotm-2.6.27-rc7+/include/linux/mm_types.h
===================================================================
--- mmotm-2.6.27-rc7+.orig/include/linux/mm_types.h
+++ mmotm-2.6.27-rc7+/include/linux/mm_types.h
@@ -94,10 +94,6 @@ struct page {
 	void *virtual;			/* Kernel virtual address (NULL if
 					   not kmapped, ie. highmem) */
 #endif /* WANT_PAGE_VIRTUAL */
-#ifdef CONFIG_CGROUP_MEM_RES_CTLR
-	unsigned long page_cgroup;
-#endif
-
 #ifdef CONFIG_KMEMCHECK
 	void *shadow;
 #endif
Index: mmotm-2.6.27-rc7+/mm/Makefile
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/Makefile
+++ mmotm-2.6.27-rc7+/mm/Makefile
@@ -34,6 +34,6 @@ obj-$(CONFIG_FS_XIP) += filemap_xip.o
 obj-$(CONFIG_MIGRATION) += migrate.o
 obj-$(CONFIG_SMP) += allocpercpu.o
 obj-$(CONFIG_QUICKLIST) += quicklist.o
-obj-$(CONFIG_CGROUP_MEM_RES_CTLR) += memcontrol.o
+obj-$(CONFIG_CGROUP_MEM_RES_CTLR) += memcontrol.o page_cgroup.o
 obj-$(CONFIG_CGROUP_MEMRLIMIT_CTLR) += memrlimitcgroup.o
 obj-$(CONFIG_KMEMTRACE) += kmemtrace.o
Index: mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
===================================================================
--- /dev/null
+++ mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
@@ -0,0 +1,90 @@
+#ifndef __LINUX_PAGE_CGROUP_H
+#define __LINUX_PAGE_CGROUP_H
+#include <linux/bit_spinlock.h>
+/*
+ * Page Cgroup can be considered as an extended mem_map.
+ * A page_cgroup page is associated with every page descriptor. The
+ * page_cgroup helps us identify information about the cgroup
+ * All page cgroups are allocated at boot or memory hotplug event,
+ * then the page cgroup for pfn always exists.
+ */
+struct page_cgroup {
+	unsigned long flags;
+	struct mem_cgroup *mem_cgroup;
+	struct page *page;
+	struct list_head lru;		/* per cgroup LRU list */
+};
+
+void __init pgdat_page_cgroup_init(struct pglist_data *pgdat);
+void __init page_cgroup_init(void);
+struct page_cgroup *lookup_page_cgroup(struct page *page);
+
+enum {
+	/* flags for mem_cgroup */
+	PCG_LOCK,  /* page cgroup is locked */
+	PCG_CACHE, /* charged as cache */
+	PCG_USED, /* this object is in use. */
+	/* flags for LRU placement */
+	PCG_ACTIVE, /* page is active in this cgroup */
+	PCG_FILE, /* page is file system backed */
+	PCG_UNEVICTABLE, /* page is unevictableable */
+};
+
+#define TESTPCGFLAG(uname, lname)			\
+static inline int PageCgroup##uname(struct page_cgroup *pc)	\
+	{ return test_bit(PCG_##lname, &pc->flags); }
+
+#define SETPCGFLAG(uname, lname)			\
+static inline void SetPageCgroup##uname(struct page_cgroup *pc)\
+	{ set_bit(PCG_##lname, &pc->flags);  }
+
+#define CLEARPCGFLAG(uname, lname)			\
+static inline void ClearPageCgroup##uname(struct page_cgroup *pc)	\
+	{ clear_bit(PCG_##lname, &pc->flags);  }
+
+/* Cache flag is set only once (at allocation) */
+TESTPCGFLAG(Cache, CACHE)
+
+TESTPCGFLAG(Used, USED)
+CLEARPCGFLAG(Used, USED)
+
+/* LRU management flags (from global-lru definition) */
+TESTPCGFLAG(File, FILE)
+SETPCGFLAG(File, FILE)
+CLEARPCGFLAG(File, FILE)
+
+TESTPCGFLAG(Active, ACTIVE)
+SETPCGFLAG(Active, ACTIVE)
+CLEARPCGFLAG(Active, ACTIVE)
+
+TESTPCGFLAG(Unevictable, UNEVICTABLE)
+SETPCGFLAG(Unevictable, UNEVICTABLE)
+CLEARPCGFLAG(Unevictable, UNEVICTABLE)
+
+static inline int page_cgroup_nid(struct page_cgroup *pc)
+{
+	return page_to_nid(pc->page);
+}
+
+static inline enum zone_type page_cgroup_zid(struct page_cgroup *pc)
+{
+	return page_zonenum(pc->page);
+}
+
+static inline void lock_page_cgroup(struct page_cgroup *pc)
+{
+	bit_spin_lock(PCG_LOCK, &pc->flags);
+}
+
+static inline int trylock_page_cgroup(struct page_cgroup *pc)
+{
+	return bit_spin_trylock(PCG_LOCK, &pc->flags);
+}
+
+static inline void unlock_page_cgroup(struct page_cgroup *pc)
+{
+	bit_spin_unlock(PCG_LOCK, &pc->flags);
+}
+
+
+#endif
Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -35,11 +35,11 @@
 #include <linux/vmalloc.h>
 #include <linux/mm_inline.h>
 #include <linux/writeback.h>
+#include <linux/page_cgroup.h>
 
 #include <asm/uaccess.h>
 
 struct cgroup_subsys mem_cgroup_subsys __read_mostly;
-static struct kmem_cache *page_cgroup_cache __read_mostly;
 #define MEM_CGROUP_RECLAIM_RETRIES	5
 
 /*
@@ -139,94 +139,18 @@ static struct mem_cgroup init_mem_cgroup
 
 #define is_root_cgroup(cgrp)	((cgrp) == &init_mem_cgroup)
 
-
-/*
- * We use the lower bit of the page->page_cgroup pointer as a bit spin
- * lock.  We need to ensure that page->page_cgroup is at least two
- * byte aligned (based on comments from Nick Piggin).  But since
- * bit_spin_lock doesn't actually set that lock bit in a non-debug
- * uniprocessor kernel, we should avoid setting it here too.
- */
-#define PAGE_CGROUP_LOCK_BIT 	0x0
-#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
-#define PAGE_CGROUP_LOCK 	(1 << PAGE_CGROUP_LOCK_BIT)
-#else
-#define PAGE_CGROUP_LOCK	0x0
-#endif
-
-/*
- * A page_cgroup page is associated with every page descriptor. The
- * page_cgroup helps us identify information about the cgroup
- */
-struct page_cgroup {
-	struct list_head lru;		/* per cgroup LRU list */
-	struct page *page;
-	struct mem_cgroup *mem_cgroup;
-	unsigned long flags;
-};
-
-enum {
-	/* flags for mem_cgroup */
-	PCG_CACHE, /* charged as cache */
-	/* flags for LRU placement */
-	PCG_ACTIVE, /* page is active in this cgroup */
-	PCG_FILE, /* page is file system backed */
-	PCG_UNEVICTABLE, /* page is unevictableable */
-};
-
-#define TESTPCGFLAG(uname, lname)			\
-static inline int PageCgroup##uname(struct page_cgroup *pc)	\
-	{ return test_bit(PCG_##lname, &pc->flags); }
-
-#define SETPCGFLAG(uname, lname)			\
-static inline void SetPageCgroup##uname(struct page_cgroup *pc)\
-	{ set_bit(PCG_##lname, &pc->flags);  }
-
-#define CLEARPCGFLAG(uname, lname)			\
-static inline void ClearPageCgroup##uname(struct page_cgroup *pc)	\
-	{ clear_bit(PCG_##lname, &pc->flags);  }
-
-
-/* Cache flag is set only once (at allocation) */
-TESTPCGFLAG(Cache, CACHE)
-
-/* LRU management flags (from global-lru definition) */
-TESTPCGFLAG(File, FILE)
-SETPCGFLAG(File, FILE)
-CLEARPCGFLAG(File, FILE)
-
-TESTPCGFLAG(Active, ACTIVE)
-SETPCGFLAG(Active, ACTIVE)
-CLEARPCGFLAG(Active, ACTIVE)
-
-TESTPCGFLAG(Unevictable, UNEVICTABLE)
-SETPCGFLAG(Unevictable, UNEVICTABLE)
-CLEARPCGFLAG(Unevictable, UNEVICTABLE)
-
-static int page_cgroup_nid(struct page_cgroup *pc)
-{
-	return page_to_nid(pc->page);
-}
-
-static enum zone_type page_cgroup_zid(struct page_cgroup *pc)
-{
-	return page_zonenum(pc->page);
-}
-
 enum charge_type {
 	MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
 	MEM_CGROUP_CHARGE_TYPE_MAPPED,
 	MEM_CGROUP_CHARGE_TYPE_SHMEM,	/* used by page migration of shmem */
-	MEM_CGROUP_CHARGE_TYPE_FORCE,	/* used by force_empty */
 	NR_CHARGE_TYPE,
 };
 
 static const unsigned long
 pcg_default_flags[NR_CHARGE_TYPE] = {
-	((1 << PCG_CACHE) | (1 << PCG_FILE)),
-	((1 << PCG_ACTIVE)),
-	((1 << PCG_ACTIVE) | (1 << PCG_CACHE)),
-	0,
+	(1 << PCG_CACHE) | (1 << PCG_FILE) | (1 << PCG_USED) | (1 << PCG_LOCK),
+	(1 << PCG_ACTIVE) | (1 << PCG_LOCK) | (1 << PCG_USED),
+	(1 << PCG_ACTIVE) | (1 << PCG_CACHE) | (1 << PCG_USED)|  (1 << PCG_LOCK),
 };
 
 /*
@@ -308,37 +232,6 @@ struct mem_cgroup *mem_cgroup_from_task(
 				struct mem_cgroup, css);
 }
 
-static inline int page_cgroup_locked(struct page *page)
-{
-	return bit_spin_is_locked(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
-}
-
-static void page_assign_page_cgroup(struct page *page, struct page_cgroup *pc)
-{
-	VM_BUG_ON(!page_cgroup_locked(page));
-	page->page_cgroup = ((unsigned long)pc | PAGE_CGROUP_LOCK);
-}
-
-struct page_cgroup *page_get_page_cgroup(struct page *page)
-{
-	return (struct page_cgroup *) (page->page_cgroup & ~PAGE_CGROUP_LOCK);
-}
-
-static void lock_page_cgroup(struct page *page)
-{
-	bit_spin_lock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
-}
-
-static int try_lock_page_cgroup(struct page *page)
-{
-	return bit_spin_trylock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
-}
-
-static void unlock_page_cgroup(struct page *page)
-{
-	bit_spin_unlock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
-}
-
 static void __mem_cgroup_remove_list(struct mem_cgroup_per_zone *mz,
 			struct page_cgroup *pc)
 {
@@ -442,22 +335,19 @@ void mem_cgroup_move_lists(struct page *
 	 * safely get to page_cgroup without it, so just try_lock it:
 	 * mem_cgroup_isolate_pages allows for page left on wrong list.
 	 */
-	if (!try_lock_page_cgroup(page))
+	pc = lookup_page_cgroup(page);
+
+	if (!trylock_page_cgroup(pc))
 		return;
 
-	pc = page_get_page_cgroup(page);
-	if (pc) {
+	if (PageCgroupUsed(pc)) {
 		mem = pc->mem_cgroup;
 		mz = page_cgroup_zoneinfo(pc);
 		spin_lock_irqsave(&mz->lru_lock, flags);
-		/*
-		 * check against the race with move_account.
-		 */
-		if (likely(mem == pc->mem_cgroup))
-			__mem_cgroup_move_lists(pc, lru);
+		__mem_cgroup_move_lists(pc, lru);
 		spin_unlock_irqrestore(&mz->lru_lock, flags);
 	}
-	unlock_page_cgroup(page);
+	unlock_page_cgroup(pc);
 }
 
 /*
@@ -544,6 +434,8 @@ unsigned long mem_cgroup_isolate_pages(u
 	list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
 		if (scan >= nr_to_scan)
 			break;
+		if (unlikely(!PageCgroupUsed(pc)))
+			continue;
 		page = pc->page;
 
 		if (unlikely(!PageLRU(page)))
@@ -611,12 +503,12 @@ int mem_cgroup_move_account(struct page 
 		/* Now, we assume no_limit...no failure here. */
 		return ret;
 	}
-	if (!try_lock_page_cgroup(page)) {
+	if (!trylock_page_cgroup(pc)) {
 		res_counter_uncharge(&to->res, PAGE_SIZE);
 		return ret;
 	}
 
-	if (page_get_page_cgroup(page) != pc) {
+	if (!PageCgroupUsed(pc)) {
 		res_counter_uncharge(&to->res, PAGE_SIZE);
 		goto out;
 	}
@@ -634,7 +526,7 @@ int mem_cgroup_move_account(struct page 
 		res_counter_uncharge(&to->res, PAGE_SIZE);
 	}
 out:
-	unlock_page_cgroup(page);
+	unlock_page_cgroup(pc);
 
 	return ret;
 }
@@ -651,26 +543,27 @@ static int mem_cgroup_charge_common(stru
 {
 	struct mem_cgroup *mem;
 	struct page_cgroup *pc;
-	unsigned long flags;
 	unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
 	struct mem_cgroup_per_zone *mz;
+	unsigned long flags;
 
-	pc = kmem_cache_alloc(page_cgroup_cache, gfp_mask);
-	if (unlikely(pc == NULL))
-		goto err;
-
+	pc = lookup_page_cgroup(page);
+	/* can happen at boot */
+	if (unlikely(!pc))
+		return 0;
+	prefetchw(pc);
 	/*
 	 * We always charge the cgroup the mm_struct belongs to.
 	 * The mm_struct's mem_cgroup changes on task migration if the
 	 * thread group leader migrates. It's possible that mm is not
 	 * set, if so charge the init_mm (happens for pagecache usage).
 	 */
+
 	if (likely(!memcg)) {
 		rcu_read_lock();
 		mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
 		if (unlikely(!mem)) {
 			rcu_read_unlock();
-			kmem_cache_free(page_cgroup_cache, pc);
 			return 0;
 		}
 		/*
@@ -706,36 +599,34 @@ static int mem_cgroup_charge_common(stru
 		}
 	}
 
+	preempt_disable();
+	lock_page_cgroup(pc);
+	if (unlikely(PageCgroupUsed(pc))) {
+		unlock_page_cgroup(pc);
+		res_counter_uncharge(&mem->res, PAGE_SIZE);
+		css_put(&mem->css);
+		preempt_enable();
+		goto done;
+	}
 	pc->mem_cgroup = mem;
-	pc->page = page;
 	/*
 	 * If a page is accounted as a page cache, insert to inactive list.
 	 * If anon, insert to active list.
 	 */
 	pc->flags = pcg_default_flags[ctype];
 
-	lock_page_cgroup(page);
-	if (unlikely(page_get_page_cgroup(page))) {
-		unlock_page_cgroup(page);
-		res_counter_uncharge(&mem->res, PAGE_SIZE);
-		css_put(&mem->css);
-		kmem_cache_free(page_cgroup_cache, pc);
-		goto done;
-	}
-	page_assign_page_cgroup(page, pc);
-
 	mz = page_cgroup_zoneinfo(pc);
+
 	spin_lock_irqsave(&mz->lru_lock, flags);
 	__mem_cgroup_add_list(mz, pc);
 	spin_unlock_irqrestore(&mz->lru_lock, flags);
+	unlock_page_cgroup(pc);
+	preempt_enable();
 
-	unlock_page_cgroup(page);
 done:
 	return 0;
 out:
 	css_put(&mem->css);
-	kmem_cache_free(page_cgroup_cache, pc);
-err:
 	return -ENOMEM;
 }
 
@@ -743,7 +634,8 @@ int mem_cgroup_charge(struct page *page,
 {
 	if (mem_cgroup_subsys.disabled)
 		return 0;
-
+	if (PageCompound(page))
+		return 0;
 	/*
 	 * If already mapped, we don't have to account.
 	 * If page cache, page->mapping has address_space.
@@ -764,7 +656,8 @@ int mem_cgroup_cache_charge(struct page 
 {
 	if (mem_cgroup_subsys.disabled)
 		return 0;
-
+	if (PageCompound(page))
+		return 0;
 	/*
 	 * Corner case handling. This is called from add_to_page_cache()
 	 * in usual. But some FS (shmem) precharges this page before calling it
@@ -777,15 +670,16 @@ int mem_cgroup_cache_charge(struct page 
 	if (!(gfp_mask & __GFP_WAIT)) {
 		struct page_cgroup *pc;
 
-		lock_page_cgroup(page);
-		pc = page_get_page_cgroup(page);
-		if (pc) {
-			VM_BUG_ON(pc->page != page);
-			VM_BUG_ON(!pc->mem_cgroup);
-			unlock_page_cgroup(page);
+
+		pc = lookup_page_cgroup(page);
+		if (!pc)
+			return 0;
+		lock_page_cgroup(pc);
+		if (PageCgroupUsed(pc)) {
+			unlock_page_cgroup(pc);
 			return 0;
 		}
-		unlock_page_cgroup(page);
+		unlock_page_cgroup(pc);
 	}
 
 	if (unlikely(!mm))
@@ -803,7 +697,7 @@ int mem_cgroup_cache_charge(struct page 
  * uncharge if !page_mapped(page)
  */
 static void
-__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
+__mem_cgroup_uncharge_common(struct page *page)
 {
 	struct page_cgroup *pc;
 	struct mem_cgroup *mem;
@@ -812,57 +706,44 @@ __mem_cgroup_uncharge_common(struct page
 
 	if (mem_cgroup_subsys.disabled)
 		return;
+	/* check the condition we can know from page */
 
-	/*
-	 * Check if our page_cgroup is valid
-	 */
-	lock_page_cgroup(page);
-	pc = page_get_page_cgroup(page);
-	if (unlikely(!pc))
-		goto unlock;
-
-	VM_BUG_ON(pc->page != page);
+	pc = lookup_page_cgroup(page);
+	if (unlikely(!pc || !PageCgroupUsed(pc)))
+		return;
+	preempt_disable();
+	lock_page_cgroup(pc);
+	ClearPageCgroupUsed(pc);
+	unlock_page_cgroup(pc);
 
-	if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
-	    && ((PageCgroupCache(pc) || page_mapped(page))))
-		goto unlock;
-retry:
 	mem = pc->mem_cgroup;
 	mz = page_cgroup_zoneinfo(pc);
+
 	spin_lock_irqsave(&mz->lru_lock, flags);
-	if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED &&
-	    unlikely(mem != pc->mem_cgroup)) {
-		/* MAPPED account can be done without lock_page().
-		   Check race with mem_cgroup_move_account() */
-		spin_unlock_irqrestore(&mz->lru_lock, flags);
-		goto retry;
-	}
 	__mem_cgroup_remove_list(mz, pc);
 	spin_unlock_irqrestore(&mz->lru_lock, flags);
-
-	page_assign_page_cgroup(page, NULL);
-	unlock_page_cgroup(page);
-
-
-	res_counter_uncharge(&mem->res, PAGE_SIZE);
+	pc->mem_cgroup = NULL;
 	css_put(&mem->css);
+	preempt_enable();
+	res_counter_uncharge(&mem->res, PAGE_SIZE);
 
-	kmem_cache_free(page_cgroup_cache, pc);
 	return;
-unlock:
-	unlock_page_cgroup(page);
 }
 
 void mem_cgroup_uncharge_page(struct page *page)
 {
-	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
+	if (page_mapped(page))
+		return;
+	if (page->mapping && !PageAnon(page))
+		return;
+	__mem_cgroup_uncharge_common(page);
 }
 
 void mem_cgroup_uncharge_cache_page(struct page *page)
 {
 	VM_BUG_ON(page_mapped(page));
 	VM_BUG_ON(page->mapping);
-	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);
+	__mem_cgroup_uncharge_common(page);
 }
 
 /*
@@ -878,9 +759,9 @@ int mem_cgroup_prepare_migration(struct 
 	if (mem_cgroup_subsys.disabled)
 		return 0;
 
-	lock_page_cgroup(page);
-	pc = page_get_page_cgroup(page);
-	if (pc) {
+	pc = lookup_page_cgroup(page);
+	lock_page_cgroup(pc);
+	if (PageCgroupUsed(pc)) {
 		mem = pc->mem_cgroup;
 		css_get(&mem->css);
 		if (PageCgroupCache(pc)) {
@@ -890,7 +771,7 @@ int mem_cgroup_prepare_migration(struct 
 				ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
 		}
 	}
-	unlock_page_cgroup(page);
+	unlock_page_cgroup(pc);
 	if (mem) {
 		ret = mem_cgroup_charge_common(newpage, NULL, GFP_KERNEL,
 			ctype, mem);
@@ -914,8 +795,7 @@ void mem_cgroup_end_migration(struct pag
 	 *    care it.
 	 */
 	if (!newpage->mapping)
-		__mem_cgroup_uncharge_common(newpage,
-					 MEM_CGROUP_CHARGE_TYPE_FORCE);
+		__mem_cgroup_uncharge_common(newpage);
 	else if (PageAnon(newpage))
 		mem_cgroup_uncharge_page(newpage);
 }
@@ -997,6 +877,8 @@ static void mem_cgroup_force_empty_list(
 	spin_lock_irqsave(&mz->lru_lock, flags);
 	list_for_each_entry_safe(pc, tmp, list, lru) {
 		page = pc->page;
+		if (!PageCgroupUsed(pc))
+			continue;
 		/* For avoiding race with speculative page cache handling. */
 		if (!PageLRU(page) || !get_page_unless_zero(page)) {
 			continue;
@@ -1270,8 +1152,8 @@ mem_cgroup_create(struct cgroup_subsys *
 	int node;
 
 	if (unlikely((cont->parent) == NULL)) {
+		page_cgroup_init();
 		mem = &init_mem_cgroup;
-		page_cgroup_cache = KMEM_CACHE(page_cgroup, SLAB_PANIC);
 	} else {
 		mem = mem_cgroup_alloc();
 		if (!mem)
Index: mmotm-2.6.27-rc7+/mm/page_alloc.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/page_alloc.c
+++ mmotm-2.6.27-rc7+/mm/page_alloc.c
@@ -44,7 +44,7 @@
 #include <linux/backing-dev.h>
 #include <linux/fault-inject.h>
 #include <linux/page-isolation.h>
-#include <linux/memcontrol.h>
+#include <linux/page_cgroup.h>
 #include <linux/debugobjects.h>
 
 #include <asm/tlbflush.h>
@@ -223,17 +223,12 @@ static inline int bad_range(struct zone 
 
 static void bad_page(struct page *page)
 {
-	void *pc = page_get_page_cgroup(page);
-
 	printk(KERN_EMERG "Bad page state in process '%s'\n" KERN_EMERG
 		"page:%p flags:0x%0*lx mapping:%p mapcount:%d count:%d\n",
 		current->comm, page, (int)(2*sizeof(unsigned long)),
 		(unsigned long)page->flags, page->mapping,
 		page_mapcount(page), page_count(page));
-	if (pc) {
-		printk(KERN_EMERG "cgroup:%p\n", pc);
-		page_reset_bad_cgroup(page);
-	}
+
 	printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n"
 		KERN_EMERG "Backtrace:\n");
 	dump_stack();
@@ -472,7 +467,6 @@ static inline void free_pages_check(stru
 	free_page_mlock(page);
 	if (unlikely(page_mapcount(page) |
 		(page->mapping != NULL)  |
-		(page_get_page_cgroup(page) != NULL) |
 		(page_count(page) != 0)  |
 		(page->flags & PAGE_FLAGS_CHECK_AT_FREE)))
 		bad_page(page);
@@ -609,7 +603,6 @@ static void prep_new_page(struct page *p
 {
 	if (unlikely(page_mapcount(page) |
 		(page->mapping != NULL)  |
-		(page_get_page_cgroup(page) != NULL) |
 		(page_count(page) != 0)  |
 		(page->flags & PAGE_FLAGS_CHECK_AT_PREP)))
 		bad_page(page);
@@ -3495,6 +3488,7 @@ static void __paginginit free_area_init_
 	pgdat->nr_zones = 0;
 	init_waitqueue_head(&pgdat->kswapd_wait);
 	pgdat->kswapd_max_order = 0;
+	pgdat_page_cgroup_init(pgdat);
 	
 	for (j = 0; j < MAX_NR_ZONES; j++) {
 		struct zone *zone = pgdat->node_zones + j;
Index: mmotm-2.6.27-rc7+/include/linux/mmzone.h
===================================================================
--- mmotm-2.6.27-rc7+.orig/include/linux/mmzone.h
+++ mmotm-2.6.27-rc7+/include/linux/mmzone.h
@@ -602,8 +602,11 @@ typedef struct pglist_data {
 	struct zone node_zones[MAX_NR_ZONES];
 	struct zonelist node_zonelists[MAX_ZONELISTS];
 	int nr_zones;
-#ifdef CONFIG_FLAT_NODE_MEM_MAP
+#ifdef CONFIG_FLAT_NODE_MEM_MAP	/* means !SPARSEMEM */
 	struct page *node_mem_map;
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+	struct page_cgroup *node_page_cgroup;
+#endif
 #endif
 	struct bootmem_data *bdata;
 #ifdef CONFIG_MEMORY_HOTPLUG
@@ -932,6 +935,7 @@ static inline unsigned long early_pfn_to
 #endif
 
 struct page;
+struct page_cgroup;
 struct mem_section {
 	/*
 	 * This is, logically, a pointer to an array of struct
@@ -949,6 +953,14 @@ struct mem_section {
 
 	/* See declaration of similar field in struct zone */
 	unsigned long *pageblock_flags;
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+	/*
+  	 * If !SPARSEMEM, pgdat doesn't have page_cgroup pointer. We use
+	 * section. (see memcontrol.h/page_cgroup.h about this.)
+	 */
+	struct page_cgroup *page_cgroup;
+	unsigned long pad;
+#endif
 };
 
 #ifdef CONFIG_SPARSEMEM_EXTREME
Index: mmotm-2.6.27-rc7+/include/linux/memcontrol.h
===================================================================
--- mmotm-2.6.27-rc7+.orig/include/linux/memcontrol.h
+++ mmotm-2.6.27-rc7+/include/linux/memcontrol.h
@@ -29,7 +29,6 @@ struct mm_struct;
 
 #define page_reset_bad_cgroup(page)	((page)->page_cgroup = 0)
 
-extern struct page_cgroup *page_get_page_cgroup(struct page *page);
 extern int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
 				gfp_t gfp_mask);
 extern int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
@@ -72,16 +71,8 @@ extern void mem_cgroup_record_reclaim_pr
 extern long mem_cgroup_calc_reclaim(struct mem_cgroup *mem, struct zone *zone,
 					int priority, enum lru_list lru);
 
-#else /* CONFIG_CGROUP_MEM_RES_CTLR */
-static inline void page_reset_bad_cgroup(struct page *page)
-{
-}
-
-static inline struct page_cgroup *page_get_page_cgroup(struct page *page)
-{
-	return NULL;
-}
 
+#else /* CONFIG_CGROUP_MEM_RES_CTLR */
 static inline int mem_cgroup_charge(struct page *page,
 					struct mm_struct *mm, gfp_t gfp_mask)
 {

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[PATCH(fixed) 10/12] free page cgroup from LRU in lazy

[KAMEZAWA Hiroyuki]

adjustment for changes in 9/12(fixed)
==
Free page_cgroup from its LRU in batched manner.

When uncharge() is called, page is pushed onto per-cpu vector and
removed from LRU, later.. This routine resembles to global LRU's pagevec.
This patch is half of the whole patch and a set with following lazy LRU add
patch.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 mm/memcontrol.c |  164 +++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 152 insertions(+), 12 deletions(-)

Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -36,6 +36,7 @@
 #include <linux/mm_inline.h>
 #include <linux/writeback.h>
 #include <linux/page_cgroup.h>
+#include <linux/cpu.h>
 
 #include <asm/uaccess.h>
 
@@ -531,6 +532,116 @@ out:
 	return ret;
 }
 
+
+#define MEMCG_PCPVEC_SIZE	(14)	/* size of pagevec */
+struct memcg_percpu_vec {
+	int nr;
+	int limit;
+	struct page_cgroup *vec[MEMCG_PCPVEC_SIZE];
+};
+static DEFINE_PER_CPU(struct memcg_percpu_vec, memcg_free_vec);
+
+static void
+__release_page_cgroup(struct memcg_percpu_vec *mpv)
+{
+	unsigned long flags;
+	struct mem_cgroup_per_zone *mz, *prev_mz;
+	struct page_cgroup *pc;
+	int i, nr;
+
+	local_irq_save(flags);
+	nr = mpv->nr;
+	mpv->nr = 0;
+	prev_mz = NULL;
+	for (i = nr - 1; i >= 0; i--) {
+		pc = mpv->vec[i];
+		VM_BUG_ON(PageCgroupUsed(pc));
+		mz = page_cgroup_zoneinfo(pc);
+		if (prev_mz != mz) {
+			if (prev_mz)
+				spin_unlock(&prev_mz->lru_lock);
+			prev_mz = mz;
+			spin_lock(&mz->lru_lock);
+		}
+		__mem_cgroup_remove_list(mz, pc);
+		css_put(&pc->mem_cgroup->css);
+		pc->mem_cgroup = NULL;
+	}
+	if (prev_mz)
+		spin_unlock(&prev_mz->lru_lock);
+	local_irq_restore(flags);
+
+}
+
+static void
+release_page_cgroup(struct page_cgroup *pc)
+{
+	struct memcg_percpu_vec *mpv;
+
+	mpv = &get_cpu_var(memcg_free_vec);
+	mpv->vec[mpv->nr++] = pc;
+	if (mpv->nr >= mpv->limit)
+		__release_page_cgroup(mpv);
+	put_cpu_var(memcg_free_vec);
+}
+
+static void page_cgroup_start_cache_cpu(int cpu)
+{
+	struct memcg_percpu_vec *mpv;
+	mpv = &per_cpu(memcg_free_vec, cpu);
+	mpv->limit = MEMCG_PCPVEC_SIZE;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void page_cgroup_stop_cache_cpu(int cpu)
+{
+	struct memcg_percpu_vec *mpv;
+	mpv = &per_cpu(memcg_free_vec, cpu);
+	mpv->limit = 0;
+}
+#endif
+
+
+/*
+ * Used when freeing memory resource controller to remove all
+ * page_cgroup (in obsolete list).
+ */
+static DEFINE_MUTEX(memcg_force_drain_mutex);
+
+static void drain_page_cgroup_local(struct work_struct *work)
+{
+	struct memcg_percpu_vec *mpv;
+	mpv = &get_cpu_var(memcg_free_vec);
+	__release_page_cgroup(mpv);
+	put_cpu_var(mpv);
+}
+
+static void drain_page_cgroup_cpu(int cpu)
+{
+	int local_cpu;
+	struct work_struct work;
+
+	local_cpu = get_cpu();
+	if (local_cpu == cpu) {
+		drain_page_cgroup_local(NULL);
+		put_cpu();
+		return;
+	}
+	put_cpu();
+
+	INIT_WORK(&work, drain_page_cgroup_local);
+	schedule_work_on(cpu, &work);
+	flush_work(&work);
+}
+
+static void drain_page_cgroup_all(void)
+{
+	mutex_lock(&memcg_force_drain_mutex);
+	schedule_on_each_cpu(drain_page_cgroup_local);
+	mutex_unlock(&memcg_force_drain_mutex);
+}
+
+
 /*
  * Charge the memory controller for page usage.
  * Return
@@ -701,8 +812,6 @@ __mem_cgroup_uncharge_common(struct page
 {
 	struct page_cgroup *pc;
 	struct mem_cgroup *mem;
-	struct mem_cgroup_per_zone *mz;
-	unsigned long flags;
 
 	if (mem_cgroup_subsys.disabled)
 		return;
@@ -715,16 +824,10 @@ __mem_cgroup_uncharge_common(struct page
 	lock_page_cgroup(pc);
 	ClearPageCgroupUsed(pc);
 	unlock_page_cgroup(pc);
+	preempt_enable();
 
 	mem = pc->mem_cgroup;
-	mz = page_cgroup_zoneinfo(pc);
-
-	spin_lock_irqsave(&mz->lru_lock, flags);
-	__mem_cgroup_remove_list(mz, pc);
-	spin_unlock_irqrestore(&mz->lru_lock, flags);
-	pc->mem_cgroup = NULL;
-	css_put(&mem->css);
-	preempt_enable();
+	release_page_cgroup(pc);
 	res_counter_uncharge(&mem->res, PAGE_SIZE);
 
 	return;
@@ -880,9 +983,8 @@ static void mem_cgroup_force_empty_list(
 		if (!PageCgroupUsed(pc))
 			continue;
 		/* For avoiding race with speculative page cache handling. */
-		if (!PageLRU(page) || !get_page_unless_zero(page)) {
+		if (!PageLRU(page) || !get_page_unless_zero(page))
 			continue;
-		}
 		mem_cgroup_move_account(page, pc, mem, &init_mem_cgroup);
 		put_page(page);
 		if (atomic_read(&mem->css.cgroup->count) > 0)
@@ -919,8 +1021,10 @@ static int mem_cgroup_force_empty(struct
 		 * While walking our own LRU, we also checks LRU bit on page.
 		 * If a page is on pagevec, it's not on LRU and we cannot
 		 * grab it. Calling lru_add_drain_all() here.
+		 * memory cgroup's its own vector shold be flushed, too.
 		 */
 		lru_add_drain_all();
+		drain_page_cgroup_all();
 		for_each_node_state(node, N_HIGH_MEMORY) {
 			for (zid = 0; zid < MAX_NR_ZONES; zid++) {
 				mz = mem_cgroup_zoneinfo(mem, node, zid);
@@ -1144,6 +1248,38 @@ static void mem_cgroup_free(struct mem_c
 		vfree(mem);
 }
 
+static void mem_cgroup_init_pcp(int cpu)
+{
+	page_cgroup_start_cache_cpu(cpu);
+}
+
+static int cpu_memcgroup_callback(struct notifier_block *nb,
+			unsigned long action, void *hcpu)
+{
+	int cpu = (long)hcpu;
+
+	switch(action) {
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		mem_cgroup_init_pcp(cpu);
+		break;
+#ifdef CONFIG_HOTPLUG_CPU
+	case CPU_DOWN_PREPARE:
+	case CPU_DOWN_PREPARE_FROZEN:
+		page_cgroup_stop_cache_cpu(cpu);
+		drain_page_cgroup_cpu(cpu);
+		break;
+#endif
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block __refdata memcgroup_nb =
+{
+	.notifier_call = cpu_memcgroup_callback,
+};
 
 static struct cgroup_subsys_state *
 mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
@@ -1154,6 +1290,10 @@ mem_cgroup_create(struct cgroup_subsys *
 	if (unlikely((cont->parent) == NULL)) {
 		page_cgroup_init();
 		mem = &init_mem_cgroup;
+		cpu_memcgroup_callback(&memcgroup_nb,
+					(unsigned long)CPU_UP_PREPARE,
+					(void *)(long)smp_processor_id());
+		register_hotcpu_notifier(&memcgroup_nb);
 	} else {
 		mem = mem_cgroup_alloc();
 		if (!mem)

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[PATCH(fixed) 11/12] free page cgroup from LRU in add

[KAMEZAWA Hiroyuki]

Fixed HUNK with 9/12(fixed)
==
Delaying add_to_lru() and do it in batched manner like page_vec.
For doing that 2 flags PCG_USED and PCG_LRU.

If PCG_LRU is set, page is on LRU. It safe to access LRU via page_cgroup.
(under some lock.)

For avoiding race, this patch uses TestSetPageCgroupUsed().
and checking PCG_USED bit and PCG_LRU bit in add/free vector.
By this, lock_page_cgroup() in mem_cgroup_charge() is removed.

(I don't want to call lock_page_cgroup() under mz->lru_lock when 
 add/free vector core logic. So, TestSetPageCgroupUsed() logic is added.
 TestSet is an easy way to avoid unneccesary nest of locks.)


Changelog: v3 -> v5.
 - removed css_get/put per page_cgroup struct.
   Now, *new* force_empty checks there is page_cgroup on the memcg.
   We don't need to be afraid of leak.

Changelog: v2 -> v3
 - added TRANSIT flag and removed lock from core logic.
Changelog: v1 -> v2:
 - renamed function name from use_page_cgroup to set_page_cgroup_lru().

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 include/linux/page_cgroup.h |   10 +++
 mm/memcontrol.c             |  121 +++++++++++++++++++++++++++++++-------------
 2 files changed, 96 insertions(+), 35 deletions(-)

Index: mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
===================================================================
--- mmotm-2.6.27-rc7+.orig/include/linux/page_cgroup.h
+++ mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
@@ -24,6 +24,7 @@ enum {
 	PCG_LOCK,  /* page cgroup is locked */
 	PCG_CACHE, /* charged as cache */
 	PCG_USED, /* this object is in use. */
+	PCG_LRU, /* this is on LRU */
 	/* flags for LRU placement */
 	PCG_ACTIVE, /* page is active in this cgroup */
 	PCG_FILE, /* page is file system backed */
@@ -42,11 +43,20 @@ static inline void SetPageCgroup##uname(
 static inline void ClearPageCgroup##uname(struct page_cgroup *pc)	\
 	{ clear_bit(PCG_##lname, &pc->flags);  }
 
+#define TESTSETPCGFLAG(uname, lname)\
+static inline int TestSetPageCgroup##uname(struct page_cgroup *pc)	\
+	{ return test_and_set_bit(PCG_##lname, &pc->flags);  }
+
 /* Cache flag is set only once (at allocation) */
 TESTPCGFLAG(Cache, CACHE)
 
 TESTPCGFLAG(Used, USED)
 CLEARPCGFLAG(Used, USED)
+TESTSETPCGFLAG(Used, USED)
+
+TESTPCGFLAG(LRU, LRU)
+SETPCGFLAG(LRU, LRU)
+CLEARPCGFLAG(LRU, LRU)
 
 /* LRU management flags (from global-lru definition) */
 TESTPCGFLAG(File, FILE)
Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -149,9 +149,9 @@ enum charge_type {
 
 static const unsigned long
 pcg_default_flags[NR_CHARGE_TYPE] = {
-	(1 << PCG_CACHE) | (1 << PCG_FILE) | (1 << PCG_USED) | (1 << PCG_LOCK),
-	(1 << PCG_ACTIVE) | (1 << PCG_LOCK) | (1 << PCG_USED),
-	(1 << PCG_ACTIVE) | (1 << PCG_CACHE) | (1 << PCG_USED)|  (1 << PCG_LOCK),
+	(1 << PCG_CACHE) | (1 << PCG_FILE) | (1 << PCG_USED),
+	(1 << PCG_ACTIVE) | (1 << PCG_USED),
+	(1 << PCG_ACTIVE) | (1 << PCG_CACHE) | (1 << PCG_USED),
 };
 
 /*
@@ -193,7 +193,6 @@ page_cgroup_zoneinfo(struct page_cgroup 
 	struct mem_cgroup *mem = pc->mem_cgroup;
 	int nid = page_cgroup_nid(pc);
 	int zid = page_cgroup_zid(pc);
-
 	return mem_cgroup_zoneinfo(mem, nid, zid);
 }
 
@@ -341,7 +340,7 @@ void mem_cgroup_move_lists(struct page *
 	if (!trylock_page_cgroup(pc))
 		return;
 
-	if (PageCgroupUsed(pc)) {
+	if (PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
 		mem = pc->mem_cgroup;
 		mz = page_cgroup_zoneinfo(pc);
 		spin_lock_irqsave(&mz->lru_lock, flags);
@@ -500,6 +499,9 @@ int mem_cgroup_move_account(struct page 
 	from_mz =  mem_cgroup_zoneinfo(from, nid, zid);
 	to_mz =  mem_cgroup_zoneinfo(to, nid, zid);
 
+	if (!PageCgroupLRU(pc))
+		return ret;
+
 	if (res_counter_charge(&to->res, PAGE_SIZE)) {
 		/* Now, we assume no_limit...no failure here. */
 		return ret;
@@ -516,10 +518,8 @@ int mem_cgroup_move_account(struct page 
 
 	if (spin_trylock(&to_mz->lru_lock)) {
 		__mem_cgroup_remove_list(from_mz, pc);
-		css_put(&from->css);
 		res_counter_uncharge(&from->res, PAGE_SIZE);
 		pc->mem_cgroup = to;
-		css_get(&to->css);
 		__mem_cgroup_add_list(to_mz, pc);
 		ret = 0;
 		spin_unlock(&to_mz->lru_lock);
@@ -540,6 +540,7 @@ struct memcg_percpu_vec {
 	struct page_cgroup *vec[MEMCG_PCPVEC_SIZE];
 };
 static DEFINE_PER_CPU(struct memcg_percpu_vec, memcg_free_vec);
+static DEFINE_PER_CPU(struct memcg_percpu_vec, memcg_add_vec);
 
 static void
 __release_page_cgroup(struct memcg_percpu_vec *mpv)
@@ -555,7 +556,6 @@ __release_page_cgroup(struct memcg_percp
 	prev_mz = NULL;
 	for (i = nr - 1; i >= 0; i--) {
 		pc = mpv->vec[i];
-		VM_BUG_ON(PageCgroupUsed(pc));
 		mz = page_cgroup_zoneinfo(pc);
 		if (prev_mz != mz) {
 			if (prev_mz)
@@ -563,9 +563,10 @@ __release_page_cgroup(struct memcg_percp
 			prev_mz = mz;
 			spin_lock(&mz->lru_lock);
 		}
-		__mem_cgroup_remove_list(mz, pc);
-		css_put(&pc->mem_cgroup->css);
-		pc->mem_cgroup = NULL;
+		if (!PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
+			__mem_cgroup_remove_list(mz, pc);
+			ClearPageCgroupLRU(pc);
+		}
 	}
 	if (prev_mz)
 		spin_unlock(&prev_mz->lru_lock);
@@ -574,10 +575,43 @@ __release_page_cgroup(struct memcg_percp
 }
 
 static void
+__set_page_cgroup_lru(struct memcg_percpu_vec *mpv)
+{
+	unsigned long flags;
+	struct mem_cgroup_per_zone *mz, *prev_mz;
+	struct page_cgroup *pc;
+	int i, nr;
+
+	local_irq_save(flags);
+	nr = mpv->nr;
+	mpv->nr = 0;
+	prev_mz = NULL;
+
+	for (i = nr - 1; i >= 0; i--) {
+		pc = mpv->vec[i];
+		mz = page_cgroup_zoneinfo(pc);
+		if (prev_mz != mz) {
+			if (prev_mz)
+				spin_unlock(&prev_mz->lru_lock);
+			prev_mz = mz;
+			spin_lock(&mz->lru_lock);
+		}
+		if (PageCgroupUsed(pc) && !PageCgroupLRU(pc)) {
+			SetPageCgroupLRU(pc);
+			__mem_cgroup_add_list(mz, pc);
+		}
+	}
+
+	if (prev_mz)
+		spin_unlock(&prev_mz->lru_lock);
+	local_irq_restore(flags);
+
+}
+
+static void
 release_page_cgroup(struct page_cgroup *pc)
 {
 	struct memcg_percpu_vec *mpv;
-
 	mpv = &get_cpu_var(memcg_free_vec);
 	mpv->vec[mpv->nr++] = pc;
 	if (mpv->nr >= mpv->limit)
@@ -585,11 +619,25 @@ release_page_cgroup(struct page_cgroup *
 	put_cpu_var(memcg_free_vec);
 }
 
+static void
+set_page_cgroup_lru(struct page_cgroup *pc)
+{
+	struct memcg_percpu_vec *mpv;
+
+	mpv = &get_cpu_var(memcg_add_vec);
+	mpv->vec[mpv->nr++] = pc;
+	if (mpv->nr >= mpv->limit)
+		__set_page_cgroup_lru(mpv);
+	put_cpu_var(memcg_add_vec);
+}
+
 static void page_cgroup_start_cache_cpu(int cpu)
 {
 	struct memcg_percpu_vec *mpv;
 	mpv = &per_cpu(memcg_free_vec, cpu);
 	mpv->limit = MEMCG_PCPVEC_SIZE;
+	mpv = &per_cpu(memcg_add_vec, cpu);
+	mpv->limit = MEMCG_PCPVEC_SIZE;
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -598,6 +646,8 @@ static void page_cgroup_stop_cache_cpu(i
 	struct memcg_percpu_vec *mpv;
 	mpv = &per_cpu(memcg_free_vec, cpu);
 	mpv->limit = 0;
+	mpv = &per_cpu(memcg_add_vec, cpu);
+	mpv->limit = 0;
 }
 #endif
 
@@ -611,6 +661,9 @@ static DEFINE_MUTEX(memcg_force_drain_mu
 static void drain_page_cgroup_local(struct work_struct *work)
 {
 	struct memcg_percpu_vec *mpv;
+	mpv = &get_cpu_var(memcg_add_vec);
+	__set_page_cgroup_lru(mpv);
+	put_cpu_var(mpv);
 	mpv = &get_cpu_var(memcg_free_vec);
 	__release_page_cgroup(mpv);
 	put_cpu_var(mpv);
@@ -677,14 +730,9 @@ static int mem_cgroup_charge_common(stru
 			rcu_read_unlock();
 			return 0;
 		}
-		/*
-		 * For every charge from the cgroup, increment reference count
-		 */
-		css_get(&mem->css);
 		rcu_read_unlock();
 	} else {
 		mem = memcg;
-		css_get(&memcg->css);
 	}
 
 	while (unlikely(res_counter_charge(&mem->res, PAGE_SIZE))) {
@@ -711,33 +759,36 @@ static int mem_cgroup_charge_common(stru
 	}
 
 	preempt_disable();
-	lock_page_cgroup(pc);
-	if (unlikely(PageCgroupUsed(pc))) {
-		unlock_page_cgroup(pc);
+	if (TestSetPageCgroupUsed(pc)) {
 		res_counter_uncharge(&mem->res, PAGE_SIZE);
-		css_put(&mem->css);
 		preempt_enable();
 		goto done;
 	}
-	pc->mem_cgroup = mem;
 	/*
-	 * If a page is accounted as a page cache, insert to inactive list.
-	 * If anon, insert to active list.
-	 */
-	pc->flags = pcg_default_flags[ctype];
-
-	mz = page_cgroup_zoneinfo(pc);
+ 	 *  page cgroup is *unused* now....but....
+ 	 *  We can assume old mem_cgroup's metadata is still available
+ 	 *  because pc is not on stale LRU after force_empty() is called.
+ 	 */
+	if (likely(!PageCgroupLRU(pc)))
+		pc->flags = pcg_default_flags[ctype];
+	else {
+		mz = page_cgroup_zoneinfo(pc);
+		spin_lock_irqsave(&mz->lru_lock, flags);
+		if (PageCgroupLRU(pc)) {
+			__mem_cgroup_remove_list(mz, pc);
+			ClearPageCgroupLRU(pc);
+		}
+		pc->flags = pcg_default_flags[ctype];
+		spin_unlock_irqrestore(&mz->lru_lock, flags);
+	}
 
-	spin_lock_irqsave(&mz->lru_lock, flags);
-	__mem_cgroup_add_list(mz, pc);
-	spin_unlock_irqrestore(&mz->lru_lock, flags);
-	unlock_page_cgroup(pc);
+	pc->mem_cgroup = mem;
+	set_page_cgroup_lru(pc);
 	preempt_enable();
 
 done:
 	return 0;
 out:
-	css_put(&mem->css);
 	return -ENOMEM;
 }
 
@@ -823,12 +874,12 @@ __mem_cgroup_uncharge_common(struct page
 	preempt_disable();
 	lock_page_cgroup(pc);
 	ClearPageCgroupUsed(pc);
+	mem = pc->mem_cgroup;
 	unlock_page_cgroup(pc);
 	preempt_enable();
+	res_counter_uncharge(&mem->res, PAGE_SIZE);
 
-	mem = pc->mem_cgroup;
 	release_page_cgroup(pc);
-	res_counter_uncharge(&mem->res, PAGE_SIZE);
 
 	return;
 }

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> Allocate all page_cgroup at boot and remove page_cgroup poitner
> from struct page. This patch adds an interface as
> 
>  struct page_cgroup *lookup_page_cgroup(struct page*)
> 
> All FLATMEM/DISCONTIGMEM/SPARSEMEM  and MEMORY_HOTPLUG is supported.
> 
> Remove page_cgroup pointer reduces the amount of memory by
>  - 4 bytes per PAGE_SIZE.
>  - 8 bytes per PAGE_SIZE
> if memory controller is disabled. (even if configured.)
> meta data usage of this is no problem in FLATMEM/DISCONTIGMEM.
> On SPARSEMEM, this makes mem_section[] size twice.
> 
> On usual 8GB x86-32 server, this saves 8MB of NORMAL_ZONE memory.
> On my x86-64 server with 48GB of memory, this saves 96MB of memory.
> (and uses xx kbytes for mem_section.)
> I think this reduction makes sense.
> 
> By pre-allocation, kmalloc/kfree in charge/uncharge are removed. 
> This means
>   - we're not necessary to be afraid of kmalloc faiulre.
>     (this can happen because of gfp_mask type.)
>   - we can avoid calling kmalloc/kfree.
>   - we can avoid allocating tons of small objects which can be fragmented.
>   - we can know what amount of memory will be used for this extra-lru handling.
> 
> I added printk message as
> 
> 	"allocated %ld bytes of page_cgroup"
>         "please try cgroup_disable=memory option if you don't want"
> 
> maybe enough informative for users.
> 

I like the changelog very much, it tells exactly what we set out to do. Thanks
for documenting it so well.

> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
>  include/linux/memcontrol.h  |   11 -
>  include/linux/mm_types.h    |    4 
>  include/linux/mmzone.h      |    9 +
>  include/linux/page_cgroup.h |   90 +++++++++++++++
>  mm/Makefile                 |    2 
>  mm/memcontrol.c             |  258 ++++++++++++--------------------------------
>  mm/page_alloc.c             |   12 --
>  mm/page_cgroup.c            |  253 +++++++++++++++++++++++++++++++++++++++++++
>  8 files changed, 431 insertions(+), 208 deletions(-)
> 
> Index: mmotm-2.6.27-rc7+/mm/page_cgroup.c
> ===================================================================
> --- /dev/null
> +++ mmotm-2.6.27-rc7+/mm/page_cgroup.c
> @@ -0,0 +1,253 @@
> +#include <linux/mm.h>
> +#include <linux/mmzone.h>
> +#include <linux/bootmem.h>
> +#include <linux/bit_spinlock.h>
> +#include <linux/page_cgroup.h>
> +#include <linux/hash.h>
> +#include <linux/memory.h>
> +
> +static void __meminit
> +__init_page_cgroup(struct page_cgroup *pc, unsigned long pfn)
> +{
> +	pc->flags = 0;
> +	pc->mem_cgroup = NULL;
> +	pc->page = pfn_to_page(pfn);
> +}
> +static unsigned long total_usage = 0;
> +
> +#ifdef CONFIG_FLAT_NODE_MEM_MAP
> +
> +
> +void __init pgdat_page_cgroup_init(struct pglist_data *pgdat)
> +{
> +	pgdat->node_page_cgroup = NULL;
> +}
> +
> +struct page_cgroup *lookup_page_cgroup(struct page *page)
> +{
> +	unsigned long pfn = page_to_pfn(page);
> +	unsigned long offset;
> +	struct page_cgroup *base;
> +
> +	base = NODE_DATA(page_to_nid(nid))->node_page_cgroup;
> +	if (unlikely(!base))
> +		return NULL;
> +
> +	offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
> +	return base + offset;
> +}
> +
> +static int __init alloc_node_page_cgroup(int nid)
> +{
> +	struct page_cgroup *base, *pc;
> +	unsigned long table_size;
> +	unsigned long start_pfn, nr_pages, index;
> +
> +	start_pfn = NODE_DATA(nid)->node_start_pfn;
> +	nr_pages = NODE_DATA(nid)->node_spanned_pages;
> +
> +	table_size = sizeof(struct page_cgroup) * nr_pages;
> +
> +	base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
> +			table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
> +	if (!base)
> +		return -ENOMEM;
> +	for (index = 0; index < nr_pages; index++) {
> +		pc = base + index;
> +		__init_page_cgroup(pc, start_pfn + index);
> +	}
> +	NODE_DATA(nid)->node_page_cgroup = base;
> +	total_usage += table_size;
> +	return 0;
> +}
> +
> +void __init free_node_page_cgroup(int nid)
> +{
> +	unsigned long table_size;
> +	unsigned long nr_pages;
> +	struct page_cgroup *base;
> +
> +	base = NODE_DATA(nid)->node_page_cgroup;
> +	if (!base)
> +		return;
> +	nr_pages = NODE_DATA(nid)->node_spanned_pages;
> +
> +	table_size = sizeof(struct page_cgroup) * nr_pages;
> +
> +	free_bootmem_node(NODE_DATA(nid),
> +			(unsigned long)base, table_size);
> +	NODE_DATA(nid)->node_page_cgroup = NULL;
> +}
> +
> +void __init page_cgroup_init(void)
> +{
> +
> +	int nid, fail;
> +
> +	for_each_online_node(nid)  {
> +		fail = alloc_node_page_cgroup(nid);
> +		if (fail)
> +			goto fail;
> +	}
> +	printk("allocated %ld bytes of page_cgroup\n", total_usage);
> +	printk("please try cgroup_disable=memory option if you don't want\n");
> +	return;
> +fail:
> +	printk("allocation of page_cgroup was failed.\n");
> +	printk("please try cgroup_disable=memory boot option\n");
> +	panic("Out of memory");
> +}
> +
> +#else /* CONFIG_FLAT_NODE_MEM_MAP */
> +
> +struct page_cgroup *lookup_page_cgroup(struct page *page)
> +{
> +	unsigned long pfn = page_to_pfn(page);
> +	struct mem_section *section = __pfn_to_section(pfn);
> +
> +	return section->page_cgroup + pfn;
> +}
> +
> +int __meminit init_section_page_cgroup(unsigned long pfn)
> +{
> +	struct mem_section *section;
> +	struct page_cgroup *base, *pc;
> +	unsigned long table_size;
> +	int nid, index;
> +
> +	section = __pfn_to_section(pfn);
> +
> +	if (section->page_cgroup)
> +		return 0;
> +
> +	nid = page_to_nid(pfn_to_page(pfn));
> +
> +	table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
> +	base = kmalloc_node(table_size, GFP_KERNEL, nid);
> +	if (!base)
> +		base = vmalloc_node(table_size, nid);

Should we check for slab_is_available() before calling kmalloc_node? Otherwise,
we might need to fallback to alloc_bootmem_node.

> +
> +	if (!base) {
> +		printk("page cgroup allocation failure\n");
> +		return -ENOMEM;
> +	}
> +
> +	for (index = 0; index < PAGES_PER_SECTION; index++) {
> +		pc = base + index;
> +		__init_page_cgroup(pc, pfn + index);
> +	}
> +
> +	section = __pfn_to_section(pfn);
> +	section->page_cgroup = base - pfn;
> +	total_usage += table_size;
> +	return 0;
> +}
> +#ifdef CONFIG_MEMORY_HOTPLUG
> +void __free_page_cgroup(unsigned long pfn)
> +{
> +	struct mem_section *ms;
> +	struct page_cgroup *base;
> +
> +	ms = __pfn_to_section(pfn);
> +	if (!ms || !ms->page_cgroup)
> +		return;
> +	base = ms->page_cgroup + pfn;
> +	ms->page_cgroup = NULL;
> +	if (is_vmalloc_addr(base))
> +		vfree(base);
> +	else
> +		kfree(base);
> +}
> +
> +int online_page_cgroup(unsigned long start_pfn,
> +			unsigned long nr_pages,
> +			int nid)
> +{
> +	unsigned long start, end, pfn;
> +	int fail = 0;
> +
> +	start = start_pfn & (PAGES_PER_SECTION - 1);
> +	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
> +
> +	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
> +		if (!pfn_present(pfn))
> +			continue;
> +		fail = init_section_page_cgroup(pfn);
> +	}
> +	if (!fail)
> +		return 0;
> +
> +	/* rollback */
> +	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
> +		__free_page_cgroup(pfn);
> +
> +	return -ENOMEM;
> +}
> +
> +int offline_page_cgroup(unsigned long start_pfn,
> +		unsigned long nr_pages, int nid)
> +{
> +	unsigned long start, end, pfn;
> +
> +	start = start_pfn & (PAGES_PER_SECTION - 1);
> +	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
> +
> +	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
> +                __free_page_cgroup(pfn);
> +	return 0;
> +
> +}
> +
> +static int page_cgroup_callback(struct notifier_block *self,
> +			       unsigned long action, void *arg)
> +{
> +	struct memory_notify *mn = arg;
> +	int ret = 0;
> +	switch (action) {
> +	case MEM_GOING_ONLINE:
> +		ret = online_page_cgroup(mn->start_pfn,
> +				   mn->nr_pages, mn->status_change_nid);
> +		break;
> +	case MEM_CANCEL_ONLINE:
> +	case MEM_OFFLINE:
> +		offline_page_cgroup(mn->start_pfn,
> +				mn->nr_pages, mn->status_change_nid);
> +		break;
> +	case MEM_GOING_OFFLINE:
> +		break;
> +        case MEM_ONLINE:
> +	case MEM_CANCEL_OFFLINE:
> +		break;
> +	}
> +	ret = notifier_from_errno(ret);
> +	return ret;
> +}
> +
> +#endif
> +
> +void __init page_cgroup_init(void)
> +{
> +	unsigned long pfn;
> +	int fail = 0;
> +
> +	for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) {
> +		if (!pfn_present(pfn))
> +			continue;
> +		fail = init_section_page_cgroup(pfn);
> +	}
> +	if (fail) {
> +		printk("please try cgroup_disable=memory boot option\n");
> +		panic("Out of memory");
> +	} else {
> +		hotplug_memory_notifier(page_cgroup_callback, 0);
> +	}
> +	printk("allocated %ld bytes of page_cgroup\n", total_usage);
> +	printk("please try cgroup_disable=memory option if you don't want\n");
> +}
> +
> +void __init pgdat_page_cgroup_init(struct pglist_data *pgdat)
> +{
> +	return;
> +}
> +
> +#endif

I like this code very much, even though I've not tested it. I think it combines
all we've been thinking and discussing very well (from my initial flatmem based
code to Dave's suggestion of using mem_section).

> Index: mmotm-2.6.27-rc7+/include/linux/mm_types.h
> ===================================================================
> --- mmotm-2.6.27-rc7+.orig/include/linux/mm_types.h
> +++ mmotm-2.6.27-rc7+/include/linux/mm_types.h
> @@ -94,10 +94,6 @@ struct page {
>  	void *virtual;			/* Kernel virtual address (NULL if
>  					   not kmapped, ie. highmem) */
>  #endif /* WANT_PAGE_VIRTUAL */
> -#ifdef CONFIG_CGROUP_MEM_RES_CTLR
> -	unsigned long page_cgroup;
> -#endif
> -

Yay! I think we should add some documentation saying, if you think about
extending struct page, think again, look at how we did it for the memory
controller (look at memcontrol.c and page_cgroup.c).

>  #ifdef CONFIG_KMEMCHECK
>  	void *shadow;
>  #endif
> Index: mmotm-2.6.27-rc7+/mm/Makefile
> ===================================================================
> --- mmotm-2.6.27-rc7+.orig/mm/Makefile
> +++ mmotm-2.6.27-rc7+/mm/Makefile
> @@ -34,6 +34,6 @@ obj-$(CONFIG_FS_XIP) += filemap_xip.o
>  obj-$(CONFIG_MIGRATION) += migrate.o
>  obj-$(CONFIG_SMP) += allocpercpu.o
>  obj-$(CONFIG_QUICKLIST) += quicklist.o
> -obj-$(CONFIG_CGROUP_MEM_RES_CTLR) += memcontrol.o
> +obj-$(CONFIG_CGROUP_MEM_RES_CTLR) += memcontrol.o page_cgroup.o
>  obj-$(CONFIG_CGROUP_MEMRLIMIT_CTLR) += memrlimitcgroup.o
>  obj-$(CONFIG_KMEMTRACE) += kmemtrace.o
> Index: mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
> ===================================================================
> --- /dev/null
> +++ mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
> @@ -0,0 +1,90 @@
> +#ifndef __LINUX_PAGE_CGROUP_H
> +#define __LINUX_PAGE_CGROUP_H
> +#include <linux/bit_spinlock.h>
> +/*
> + * Page Cgroup can be considered as an extended mem_map.
> + * A page_cgroup page is associated with every page descriptor. The
> + * page_cgroup helps us identify information about the cgroup
> + * All page cgroups are allocated at boot or memory hotplug event,
> + * then the page cgroup for pfn always exists.
> + */
> +struct page_cgroup {
> +	unsigned long flags;
> +	struct mem_cgroup *mem_cgroup;
> +	struct page *page;
> +	struct list_head lru;		/* per cgroup LRU list */
> +};
> +
> +void __init pgdat_page_cgroup_init(struct pglist_data *pgdat);
> +void __init page_cgroup_init(void);
> +struct page_cgroup *lookup_page_cgroup(struct page *page);
> +
> +enum {
> +	/* flags for mem_cgroup */
> +	PCG_LOCK,  /* page cgroup is locked */
> +	PCG_CACHE, /* charged as cache */
> +	PCG_USED, /* this object is in use. */
> +	/* flags for LRU placement */
> +	PCG_ACTIVE, /* page is active in this cgroup */
> +	PCG_FILE, /* page is file system backed */
> +	PCG_UNEVICTABLE, /* page is unevictableable */
> +};
> +
> +#define TESTPCGFLAG(uname, lname)			\
> +static inline int PageCgroup##uname(struct page_cgroup *pc)	\
> +	{ return test_bit(PCG_##lname, &pc->flags); }
> +
> +#define SETPCGFLAG(uname, lname)			\
> +static inline void SetPageCgroup##uname(struct page_cgroup *pc)\
> +	{ set_bit(PCG_##lname, &pc->flags);  }
> +
> +#define CLEARPCGFLAG(uname, lname)			\
> +static inline void ClearPageCgroup##uname(struct page_cgroup *pc)	\
> +	{ clear_bit(PCG_##lname, &pc->flags);  }
> +
> +/* Cache flag is set only once (at allocation) */
> +TESTPCGFLAG(Cache, CACHE)
> +
> +TESTPCGFLAG(Used, USED)
> +CLEARPCGFLAG(Used, USED)
> +
> +/* LRU management flags (from global-lru definition) */
> +TESTPCGFLAG(File, FILE)
> +SETPCGFLAG(File, FILE)
> +CLEARPCGFLAG(File, FILE)
> +
> +TESTPCGFLAG(Active, ACTIVE)
> +SETPCGFLAG(Active, ACTIVE)
> +CLEARPCGFLAG(Active, ACTIVE)
> +
> +TESTPCGFLAG(Unevictable, UNEVICTABLE)
> +SETPCGFLAG(Unevictable, UNEVICTABLE)
> +CLEARPCGFLAG(Unevictable, UNEVICTABLE)
> +

Can we make this patch indepedent of the flags changes and push it in ASAP.

> +static inline int page_cgroup_nid(struct page_cgroup *pc)
> +{
> +	return page_to_nid(pc->page);
> +}
> +
> +static inline enum zone_type page_cgroup_zid(struct page_cgroup *pc)
> +{
> +	return page_zonenum(pc->page);
> +}
> +
> +static inline void lock_page_cgroup(struct page_cgroup *pc)
> +{
> +	bit_spin_lock(PCG_LOCK, &pc->flags);
> +}
> +
> +static inline int trylock_page_cgroup(struct page_cgroup *pc)
> +{
> +	return bit_spin_trylock(PCG_LOCK, &pc->flags);
> +}
> +
> +static inline void unlock_page_cgroup(struct page_cgroup *pc)
> +{
> +	bit_spin_unlock(PCG_LOCK, &pc->flags);
> +}
> +
> +
> +#endif
> Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
> ===================================================================
> --- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
> +++ mmotm-2.6.27-rc7+/mm/memcontrol.c
> @@ -35,11 +35,11 @@
>  #include <linux/vmalloc.h>
>  #include <linux/mm_inline.h>
>  #include <linux/writeback.h>
> +#include <linux/page_cgroup.h>
> 
>  #include <asm/uaccess.h>
> 
>  struct cgroup_subsys mem_cgroup_subsys __read_mostly;
> -static struct kmem_cache *page_cgroup_cache __read_mostly;
>  #define MEM_CGROUP_RECLAIM_RETRIES	5
> 
>  /*
> @@ -139,80 +139,6 @@ static struct mem_cgroup init_mem_cgroup
> 
>  #define is_root_cgroup(cgrp)	((cgrp) == &init_mem_cgroup)
> 
> -
> -/*
> - * We use the lower bit of the page->page_cgroup pointer as a bit spin
> - * lock.  We need to ensure that page->page_cgroup is at least two
> - * byte aligned (based on comments from Nick Piggin).  But since
> - * bit_spin_lock doesn't actually set that lock bit in a non-debug
> - * uniprocessor kernel, we should avoid setting it here too.
> - */
> -#define PAGE_CGROUP_LOCK_BIT 	0x0
> -#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
> -#define PAGE_CGROUP_LOCK 	(1 << PAGE_CGROUP_LOCK_BIT)
> -#else
> -#define PAGE_CGROUP_LOCK	0x0
> -#endif
> -
> -/*
> - * A page_cgroup page is associated with every page descriptor. The
> - * page_cgroup helps us identify information about the cgroup
> - */
> -struct page_cgroup {
> -	struct list_head lru;		/* per cgroup LRU list */
> -	struct page *page;
> -	struct mem_cgroup *mem_cgroup;
> -	unsigned long flags;
> -};
> -
> -enum {
> -	/* flags for mem_cgroup */
> -	PCG_CACHE, /* charged as cache */
> -	/* flags for LRU placement */
> -	PCG_ACTIVE, /* page is active in this cgroup */
> -	PCG_FILE, /* page is file system backed */
> -	PCG_UNEVICTABLE, /* page is unevictableable */
> -};
> -
> -#define TESTPCGFLAG(uname, lname)			\
> -static inline int PageCgroup##uname(struct page_cgroup *pc)	\
> -	{ return test_bit(PCG_##lname, &pc->flags); }
> -
> -#define SETPCGFLAG(uname, lname)			\
> -static inline void SetPageCgroup##uname(struct page_cgroup *pc)\
> -	{ set_bit(PCG_##lname, &pc->flags);  }
> -
> -#define CLEARPCGFLAG(uname, lname)			\
> -static inline void ClearPageCgroup##uname(struct page_cgroup *pc)	\
> -	{ clear_bit(PCG_##lname, &pc->flags);  }
> -
> -
> -/* Cache flag is set only once (at allocation) */
> -TESTPCGFLAG(Cache, CACHE)
> -
> -/* LRU management flags (from global-lru definition) */
> -TESTPCGFLAG(File, FILE)
> -SETPCGFLAG(File, FILE)
> -CLEARPCGFLAG(File, FILE)
> -
> -TESTPCGFLAG(Active, ACTIVE)
> -SETPCGFLAG(Active, ACTIVE)
> -CLEARPCGFLAG(Active, ACTIVE)
> -
> -TESTPCGFLAG(Unevictable, UNEVICTABLE)
> -SETPCGFLAG(Unevictable, UNEVICTABLE)
> -CLEARPCGFLAG(Unevictable, UNEVICTABLE)
> -
> -static int page_cgroup_nid(struct page_cgroup *pc)
> -{
> -	return page_to_nid(pc->page);
> -}
> -
> -static enum zone_type page_cgroup_zid(struct page_cgroup *pc)
> -{
> -	return page_zonenum(pc->page);
> -}
> -
>  enum charge_type {
>  	MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
>  	MEM_CGROUP_CHARGE_TYPE_MAPPED,
> @@ -223,9 +149,9 @@ enum charge_type {
> 
>  static const unsigned long
>  pcg_default_flags[NR_CHARGE_TYPE] = {
> -	((1 << PCG_CACHE) | (1 << PCG_FILE)),
> -	((1 << PCG_ACTIVE)),
> -	((1 << PCG_ACTIVE) | (1 << PCG_CACHE)),
> +	(1 << PCG_CACHE) | (1 << PCG_FILE) | (1 << PCG_USED) | (1 << PCG_LOCK),
> +	(1 << PCG_ACTIVE) | (1 << PCG_LOCK) | (1 << PCG_USED),
> +	(1 << PCG_ACTIVE) | (1 << PCG_CACHE) | (1 << PCG_USED)|  (1 << PCG_LOCK),
>  	0,
>  };
> 
> @@ -308,37 +234,6 @@ struct mem_cgroup *mem_cgroup_from_task(
>  				struct mem_cgroup, css);
>  }
> 
> -static inline int page_cgroup_locked(struct page *page)
> -{
> -	return bit_spin_is_locked(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
> -}
> -
> -static void page_assign_page_cgroup(struct page *page, struct page_cgroup *pc)
> -{
> -	VM_BUG_ON(!page_cgroup_locked(page));
> -	page->page_cgroup = ((unsigned long)pc | PAGE_CGROUP_LOCK);
> -}
> -
> -struct page_cgroup *page_get_page_cgroup(struct page *page)
> -{
> -	return (struct page_cgroup *) (page->page_cgroup & ~PAGE_CGROUP_LOCK);
> -}
> -
> -static void lock_page_cgroup(struct page *page)
> -{
> -	bit_spin_lock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
> -}
> -
> -static int try_lock_page_cgroup(struct page *page)
> -{
> -	return bit_spin_trylock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
> -}
> -
> -static void unlock_page_cgroup(struct page *page)
> -{
> -	bit_spin_unlock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
> -}
> -
>  static void __mem_cgroup_remove_list(struct mem_cgroup_per_zone *mz,
>  			struct page_cgroup *pc)
>  {
> @@ -442,22 +337,19 @@ void mem_cgroup_move_lists(struct page *
>  	 * safely get to page_cgroup without it, so just try_lock it:
>  	 * mem_cgroup_isolate_pages allows for page left on wrong list.
>  	 */
> -	if (!try_lock_page_cgroup(page))
> +	pc = lookup_page_cgroup(page);
> +
> +	if (!trylock_page_cgroup(pc))
>  		return;
> 
> -	pc = page_get_page_cgroup(page);
> -	if (pc) {
> +	if (PageCgroupUsed(pc)) {
>  		mem = pc->mem_cgroup;
>  		mz = page_cgroup_zoneinfo(pc);
>  		spin_lock_irqsave(&mz->lru_lock, flags);
> -		/*
> -		 * check against the race with move_account.
> -		 */
> -		if (likely(mem == pc->mem_cgroup))
> -			__mem_cgroup_move_lists(pc, lru);
> +		__mem_cgroup_move_lists(pc, lru);
>  		spin_unlock_irqrestore(&mz->lru_lock, flags);
>  	}
> -	unlock_page_cgroup(page);
> +	unlock_page_cgroup(pc);
>  }
> 
>  /*
> @@ -544,6 +436,8 @@ unsigned long mem_cgroup_isolate_pages(u
>  	list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
>  		if (scan >= nr_to_scan)
>  			break;
> +		if (unlikely(!PageCgroupUsed(pc)))
> +			continue;
>  		page = pc->page;
> 
>  		if (unlikely(!PageLRU(page)))
> @@ -611,12 +505,12 @@ int mem_cgroup_move_account(struct page 
>  		/* Now, we assume no_limit...no failure here. */
>  		return ret;
>  	}
> -	if (!try_lock_page_cgroup(page)) {
> +	if (!trylock_page_cgroup(pc)) {
>  		res_counter_uncharge(&to->res, PAGE_SIZE);
>  		return ret;
>  	}
> 
> -	if (page_get_page_cgroup(page) != pc) {
> +	if (!PageCgroupUsed(pc)) {
>  		res_counter_uncharge(&to->res, PAGE_SIZE);
>  		goto out;
>  	}
> @@ -634,7 +528,7 @@ int mem_cgroup_move_account(struct page 
>  		res_counter_uncharge(&to->res, PAGE_SIZE);
>  	}
>  out:
> -	unlock_page_cgroup(page);
> +	unlock_page_cgroup(pc);
> 
>  	return ret;
>  }
> @@ -651,26 +545,27 @@ static int mem_cgroup_charge_common(stru
>  {
>  	struct mem_cgroup *mem;
>  	struct page_cgroup *pc;
> -	unsigned long flags;
>  	unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
>  	struct mem_cgroup_per_zone *mz;
> +	unsigned long flags;
> 
> -	pc = kmem_cache_alloc(page_cgroup_cache, gfp_mask);
> -	if (unlikely(pc == NULL))
> -		goto err;
> -
> +	pc = lookup_page_cgroup(page);
> +	/* can happen at boot */
> +	if (unlikely(!pc))
> +		return 0;
> +	prefetchw(pc);
>  	/*
>  	 * We always charge the cgroup the mm_struct belongs to.
>  	 * The mm_struct's mem_cgroup changes on task migration if the
>  	 * thread group leader migrates. It's possible that mm is not
>  	 * set, if so charge the init_mm (happens for pagecache usage).
>  	 */
> +
>  	if (likely(!memcg)) {
>  		rcu_read_lock();
>  		mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
>  		if (unlikely(!mem)) {
>  			rcu_read_unlock();
> -			kmem_cache_free(page_cgroup_cache, pc);
>  			return 0;
>  		}
>  		/*
> @@ -706,36 +601,34 @@ static int mem_cgroup_charge_common(stru
>  		}
>  	}
> 
> +	preempt_disable();

I don't understand the preempt_disable() is it for atomic operations? I would
like to split the removal of struct page from atomic operations for performance.
I think it will make it easier to merge/review.

> +	lock_page_cgroup(pc);
> +	if (unlikely(PageCgroupUsed(pc))) {
> +		unlock_page_cgroup(pc);
> +		res_counter_uncharge(&mem->res, PAGE_SIZE);
> +		css_put(&mem->css);
> +		preempt_enable();
> +		goto done;
> +	}
>  	pc->mem_cgroup = mem;
> -	pc->page = page;
>  	/*
>  	 * If a page is accounted as a page cache, insert to inactive list.
>  	 * If anon, insert to active list.
>  	 */
>  	pc->flags = pcg_default_flags[ctype];
> 
> -	lock_page_cgroup(page);
> -	if (unlikely(page_get_page_cgroup(page))) {
> -		unlock_page_cgroup(page);
> -		res_counter_uncharge(&mem->res, PAGE_SIZE);
> -		css_put(&mem->css);
> -		kmem_cache_free(page_cgroup_cache, pc);
> -		goto done;
> -	}
> -	page_assign_page_cgroup(page, pc);
> -
>  	mz = page_cgroup_zoneinfo(pc);
> +
>  	spin_lock_irqsave(&mz->lru_lock, flags);
>  	__mem_cgroup_add_list(mz, pc);
>  	spin_unlock_irqrestore(&mz->lru_lock, flags);
> +	unlock_page_cgroup(pc);
> +	preempt_enable();
> 
> -	unlock_page_cgroup(page);
>  done:
>  	return 0;
>  out:
>  	css_put(&mem->css);
> -	kmem_cache_free(page_cgroup_cache, pc);
> -err:
>  	return -ENOMEM;
>  }
> 
> @@ -743,7 +636,8 @@ int mem_cgroup_charge(struct page *page,
>  {
>  	if (mem_cgroup_subsys.disabled)
>  		return 0;
> -
> +	if (PageCompound(page))
> +		return 0;
>  	/*
>  	 * If already mapped, we don't have to account.
>  	 * If page cache, page->mapping has address_space.
> @@ -764,7 +658,8 @@ int mem_cgroup_cache_charge(struct page 
>  {
>  	if (mem_cgroup_subsys.disabled)
>  		return 0;
> -
> +	if (PageCompound(page))
> +		return 0;
>  	/*
>  	 * Corner case handling. This is called from add_to_page_cache()
>  	 * in usual. But some FS (shmem) precharges this page before calling it
> @@ -777,15 +672,16 @@ int mem_cgroup_cache_charge(struct page 
>  	if (!(gfp_mask & __GFP_WAIT)) {
>  		struct page_cgroup *pc;
> 
> -		lock_page_cgroup(page);
> -		pc = page_get_page_cgroup(page);
> -		if (pc) {
> -			VM_BUG_ON(pc->page != page);
> -			VM_BUG_ON(!pc->mem_cgroup);
> -			unlock_page_cgroup(page);
> +
> +		pc = lookup_page_cgroup(page);
> +		if (!pc)
> +			return 0;
> +		lock_page_cgroup(pc);
> +		if (PageCgroupUsed(pc)) {
> +			unlock_page_cgroup(pc);
>  			return 0;
>  		}
> -		unlock_page_cgroup(page);
> +		unlock_page_cgroup(pc);
>  	}
> 
>  	if (unlikely(!mm))
> @@ -812,49 +708,41 @@ __mem_cgroup_uncharge_common(struct page
> 
>  	if (mem_cgroup_subsys.disabled)
>  		return;
> +	/* check the condition we can know from page */
> 
> -	/*
> -	 * Check if our page_cgroup is valid
> -	 */
> -	lock_page_cgroup(page);
> -	pc = page_get_page_cgroup(page);
> -	if (unlikely(!pc))
> -		goto unlock;
> -
> -	VM_BUG_ON(pc->page != page);
> +	pc = lookup_page_cgroup(page);
> +	if (unlikely(!pc || !PageCgroupUsed(pc)))
> +		return;
> +	preempt_disable();
> +	lock_page_cgroup(pc);
> +	if (unlikely(page_mapped(page))) {
> +		unlock_page_cgroup(pc);
> +		preempt_enable();
> +		return;
> +	}
> +	ClearPageCgroupUsed(pc);
> +	unlock_page_cgroup(pc);
> 
> -	if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
> -	    && ((PageCgroupCache(pc) || page_mapped(page))))
> -		goto unlock;
> -retry:
>  	mem = pc->mem_cgroup;
>  	mz = page_cgroup_zoneinfo(pc);
> +
>  	spin_lock_irqsave(&mz->lru_lock, flags);
> -	if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED &&
> -	    unlikely(mem != pc->mem_cgroup)) {
> -		/* MAPPED account can be done without lock_page().
> -		   Check race with mem_cgroup_move_account() */
> -		spin_unlock_irqrestore(&mz->lru_lock, flags);
> -		goto retry;
> -	}
>  	__mem_cgroup_remove_list(mz, pc);
>  	spin_unlock_irqrestore(&mz->lru_lock, flags);
> -
> -	page_assign_page_cgroup(page, NULL);
> -	unlock_page_cgroup(page);
> -
> -
> -	res_counter_uncharge(&mem->res, PAGE_SIZE);
> +	pc->mem_cgroup = NULL;
>  	css_put(&mem->css);
> +	preempt_enable();
> +	res_counter_uncharge(&mem->res, PAGE_SIZE);
> 
> -	kmem_cache_free(page_cgroup_cache, pc);
>  	return;
> -unlock:
> -	unlock_page_cgroup(page);
>  }
> 
>  void mem_cgroup_uncharge_page(struct page *page)
>  {
> +	if (page_mapped(page))
> +		return;
> +	if (page->mapping && !PageAnon(page))
> +		return;
>  	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
>  }
> 
> @@ -878,9 +766,9 @@ int mem_cgroup_prepare_migration(struct 
>  	if (mem_cgroup_subsys.disabled)
>  		return 0;
> 
> -	lock_page_cgroup(page);
> -	pc = page_get_page_cgroup(page);
> -	if (pc) {
> +	pc = lookup_page_cgroup(page);
> +	lock_page_cgroup(pc);
> +	if (PageCgroupUsed(pc)) {
>  		mem = pc->mem_cgroup;
>  		css_get(&mem->css);
>  		if (PageCgroupCache(pc)) {
> @@ -890,7 +778,7 @@ int mem_cgroup_prepare_migration(struct 
>  				ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
>  		}
>  	}
> -	unlock_page_cgroup(page);
> +	unlock_page_cgroup(pc);
>  	if (mem) {
>  		ret = mem_cgroup_charge_common(newpage, NULL, GFP_KERNEL,
>  			ctype, mem);
> @@ -997,6 +885,8 @@ static void mem_cgroup_force_empty_list(
>  	spin_lock_irqsave(&mz->lru_lock, flags);
>  	list_for_each_entry_safe(pc, tmp, list, lru) {
>  		page = pc->page;
> +		if (!PageCgroupUsed(pc))
> +			continue;
>  		/* For avoiding race with speculative page cache handling. */
>  		if (!PageLRU(page) || !get_page_unless_zero(page)) {
>  			continue;
> @@ -1270,8 +1160,8 @@ mem_cgroup_create(struct cgroup_subsys *
>  	int node;
> 
>  	if (unlikely((cont->parent) == NULL)) {
> +		page_cgroup_init();
>  		mem = &init_mem_cgroup;
> -		page_cgroup_cache = KMEM_CACHE(page_cgroup, SLAB_PANIC);
>  	} else {
>  		mem = mem_cgroup_alloc();
>  		if (!mem)
> Index: mmotm-2.6.27-rc7+/mm/page_alloc.c
> ===================================================================
> --- mmotm-2.6.27-rc7+.orig/mm/page_alloc.c
> +++ mmotm-2.6.27-rc7+/mm/page_alloc.c
> @@ -44,7 +44,7 @@
>  #include <linux/backing-dev.h>
>  #include <linux/fault-inject.h>
>  #include <linux/page-isolation.h>
> -#include <linux/memcontrol.h>
> +#include <linux/page_cgroup.h>
>  #include <linux/debugobjects.h>
> 
>  #include <asm/tlbflush.h>
> @@ -223,17 +223,12 @@ static inline int bad_range(struct zone 
> 
>  static void bad_page(struct page *page)
>  {
> -	void *pc = page_get_page_cgroup(page);
> -
>  	printk(KERN_EMERG "Bad page state in process '%s'\n" KERN_EMERG
>  		"page:%p flags:0x%0*lx mapping:%p mapcount:%d count:%d\n",
>  		current->comm, page, (int)(2*sizeof(unsigned long)),
>  		(unsigned long)page->flags, page->mapping,
>  		page_mapcount(page), page_count(page));
> -	if (pc) {
> -		printk(KERN_EMERG "cgroup:%p\n", pc);
> -		page_reset_bad_cgroup(page);
> -	}
> +
>  	printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n"
>  		KERN_EMERG "Backtrace:\n");
>  	dump_stack();
> @@ -472,7 +467,6 @@ static inline void free_pages_check(stru
>  	free_page_mlock(page);
>  	if (unlikely(page_mapcount(page) |
>  		(page->mapping != NULL)  |
> -		(page_get_page_cgroup(page) != NULL) |
>  		(page_count(page) != 0)  |
>  		(page->flags & PAGE_FLAGS_CHECK_AT_FREE)))
>  		bad_page(page);
> @@ -609,7 +603,6 @@ static void prep_new_page(struct page *p
>  {
>  	if (unlikely(page_mapcount(page) |
>  		(page->mapping != NULL)  |
> -		(page_get_page_cgroup(page) != NULL) |
>  		(page_count(page) != 0)  |
>  		(page->flags & PAGE_FLAGS_CHECK_AT_PREP)))
>  		bad_page(page);
> @@ -3495,6 +3488,7 @@ static void __paginginit free_area_init_
>  	pgdat->nr_zones = 0;
>  	init_waitqueue_head(&pgdat->kswapd_wait);
>  	pgdat->kswapd_max_order = 0;
> +	pgdat_page_cgroup_init(pgdat);
>  	
>  	for (j = 0; j < MAX_NR_ZONES; j++) {
>  		struct zone *zone = pgdat->node_zones + j;
> Index: mmotm-2.6.27-rc7+/include/linux/mmzone.h
> ===================================================================
> --- mmotm-2.6.27-rc7+.orig/include/linux/mmzone.h
> +++ mmotm-2.6.27-rc7+/include/linux/mmzone.h
> @@ -604,6 +604,9 @@ typedef struct pglist_data {
>  	int nr_zones;
>  #ifdef CONFIG_FLAT_NODE_MEM_MAP
>  	struct page *node_mem_map;
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR
> +	struct page_cgroup *node_page_cgroup;
> +#endif
>  #endif
>  	struct bootmem_data *bdata;
>  #ifdef CONFIG_MEMORY_HOTPLUG
> @@ -932,6 +935,7 @@ static inline unsigned long early_pfn_to
>  #endif
> 
>  struct page;
> +struct page_cgroup;
>  struct mem_section {
>  	/*
>  	 * This is, logically, a pointer to an array of struct
> @@ -949,6 +953,11 @@ struct mem_section {
> 
>  	/* See declaration of similar field in struct zone */
>  	unsigned long *pageblock_flags;
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR
> +	/* see page_cgroup.h */
> +	struct page_cgroup *page_cgroup;
> +	unsigned long pad;
> +#endif
>  };
> 
>  #ifdef CONFIG_SPARSEMEM_EXTREME
> Index: mmotm-2.6.27-rc7+/include/linux/memcontrol.h
> ===================================================================
> --- mmotm-2.6.27-rc7+.orig/include/linux/memcontrol.h
> +++ mmotm-2.6.27-rc7+/include/linux/memcontrol.h
> @@ -29,7 +29,6 @@ struct mm_struct;
> 
>  #define page_reset_bad_cgroup(page)	((page)->page_cgroup = 0)
> 
> -extern struct page_cgroup *page_get_page_cgroup(struct page *page);
>  extern int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
>  				gfp_t gfp_mask);
>  extern int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
> @@ -72,16 +71,8 @@ extern void mem_cgroup_record_reclaim_pr
>  extern long mem_cgroup_calc_reclaim(struct mem_cgroup *mem, struct zone *zone,
>  					int priority, enum lru_list lru);
> 
> -#else /* CONFIG_CGROUP_MEM_RES_CTLR */
> -static inline void page_reset_bad_cgroup(struct page *page)
> -{
> -}
> -
> -static inline struct page_cgroup *page_get_page_cgroup(struct page *page)
> -{
> -	return NULL;
> -}
> 
> +#else /* CONFIG_CGROUP_MEM_RES_CTLR */
>  static inline int mem_cgroup_charge(struct page *page,
>  					struct mm_struct *mm, gfp_t gfp_mask)
>  {
> 

Except for the the performance changes for atomic operations, I like this patch
very much.

For the page removal portions
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> as a co-maintainer


-- 
	Balbir

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[KAMEZAWA Hiroyuki]

On Wed, 01 Oct 2008 09:33:53 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> > +int __meminit init_section_page_cgroup(unsigned long pfn)
> > +{
> > +	struct mem_section *section;
> > +	struct page_cgroup *base, *pc;
> > +	unsigned long table_size;
> > +	int nid, index;
> > +
> > +	section = __pfn_to_section(pfn);
> > +
> > +	if (section->page_cgroup)
> > +		return 0;
> > +
> > +	nid = page_to_nid(pfn_to_page(pfn));
> > +
> > +	table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
> > +	base = kmalloc_node(table_size, GFP_KERNEL, nid);
> > +	if (!base)
> > +		base = vmalloc_node(table_size, nid);
> 
> Should we check for slab_is_available() before calling kmalloc_node? Otherwise,
> we might need to fallback to alloc_bootmem_node.
> 
That check is not necessary.
Because we use kmalloc()/vmalloc()  in mem_cgroup_create(), after this.

(We assume usual page allocateor is available here. For FLATMEM, size of 
 array can be too big for kmalloc(), etc... I use alloc_bootmem().

> > +
> > +	if (!base) {
> > +		printk("page cgroup allocation failure\n");
> > +		return -ENOMEM;
> > +	}
> > +
> > +	for (index = 0; index < PAGES_PER_SECTION; index++) {
> > +		pc = base + index;
> > +		__init_page_cgroup(pc, pfn + index);
> > +	}
> > +
> > +	section = __pfn_to_section(pfn);
> > +	section->page_cgroup = base - pfn;
> > +	total_usage += table_size;
> > +	return 0;
> > +}
> > +#ifdef CONFIG_MEMORY_HOTPLUG
> > +void __free_page_cgroup(unsigned long pfn)
> > +{
> > +	struct mem_section *ms;
> > +	struct page_cgroup *base;
> > +
> > +	ms = __pfn_to_section(pfn);
> > +	if (!ms || !ms->page_cgroup)
> > +		return;
> > +	base = ms->page_cgroup + pfn;
> > +	ms->page_cgroup = NULL;
> > +	if (is_vmalloc_addr(base))
> > +		vfree(base);
> > +	else
> > +		kfree(base);
> > +}
> > +
> > +int online_page_cgroup(unsigned long start_pfn,
> > +			unsigned long nr_pages,
> > +			int nid)
> > +{
> > +	unsigned long start, end, pfn;
> > +	int fail = 0;
> > +
> > +	start = start_pfn & (PAGES_PER_SECTION - 1);
> > +	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
> > +
> > +	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
> > +		if (!pfn_present(pfn))
> > +			continue;
> > +		fail = init_section_page_cgroup(pfn);
> > +	}
> > +	if (!fail)
> > +		return 0;
> > +
> > +	/* rollback */
> > +	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
> > +		__free_page_cgroup(pfn);
> > +
> > +	return -ENOMEM;
> > +}
> > +
> > +int offline_page_cgroup(unsigned long start_pfn,
> > +		unsigned long nr_pages, int nid)
> > +{
> > +	unsigned long start, end, pfn;
> > +
> > +	start = start_pfn & (PAGES_PER_SECTION - 1);
> > +	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
> > +
> > +	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
> > +                __free_page_cgroup(pfn);
> > +	return 0;
> > +
> > +}
> > +
> > +static int page_cgroup_callback(struct notifier_block *self,
> > +			       unsigned long action, void *arg)
> > +{
> > +	struct memory_notify *mn = arg;
> > +	int ret = 0;
> > +	switch (action) {
> > +	case MEM_GOING_ONLINE:
> > +		ret = online_page_cgroup(mn->start_pfn,
> > +				   mn->nr_pages, mn->status_change_nid);
> > +		break;
> > +	case MEM_CANCEL_ONLINE:
> > +	case MEM_OFFLINE:
> > +		offline_page_cgroup(mn->start_pfn,
> > +				mn->nr_pages, mn->status_change_nid);
> > +		break;
> > +	case MEM_GOING_OFFLINE:
> > +		break;
> > +        case MEM_ONLINE:
> > +	case MEM_CANCEL_OFFLINE:
> > +		break;
> > +	}
> > +	ret = notifier_from_errno(ret);
> > +	return ret;
> > +}
> > +
> > +#endif
> > +
> > +void __init page_cgroup_init(void)
> > +{
> > +	unsigned long pfn;
> > +	int fail = 0;
> > +
> > +	for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) {
> > +		if (!pfn_present(pfn))
> > +			continue;
> > +		fail = init_section_page_cgroup(pfn);
> > +	}
> > +	if (fail) {
> > +		printk("please try cgroup_disable=memory boot option\n");
> > +		panic("Out of memory");
> > +	} else {
> > +		hotplug_memory_notifier(page_cgroup_callback, 0);
> > +	}
> > +	printk("allocated %ld bytes of page_cgroup\n", total_usage);
> > +	printk("please try cgroup_disable=memory option if you don't want\n");
> > +}
> > +
> > +void __init pgdat_page_cgroup_init(struct pglist_data *pgdat)
> > +{
> > +	return;
> > +}
> > +
> > +#endif
> 
> I like this code very much, even though I've not tested it. I think it combines
> all we've been thinking and discussing very well (from my initial flatmem based
> code to Dave's suggestion of using mem_section).
> 
> > Index: mmotm-2.6.27-rc7+/include/linux/mm_types.h
> > ===================================================================
> > --- mmotm-2.6.27-rc7+.orig/include/linux/mm_types.h
> > +++ mmotm-2.6.27-rc7+/include/linux/mm_types.h
> > @@ -94,10 +94,6 @@ struct page {
> >  	void *virtual;			/* Kernel virtual address (NULL if
> >  					   not kmapped, ie. highmem) */
> >  #endif /* WANT_PAGE_VIRTUAL */
> > -#ifdef CONFIG_CGROUP_MEM_RES_CTLR
> > -	unsigned long page_cgroup;
> > -#endif
> > -
> 
> Yay! I think we should add some documentation saying, if you think about
> extending struct page, think again, look at how we did it for the memory
> controller (look at memcontrol.c and page_cgroup.c).
> 
???? it's usually not accepted. I've seen such case very much.
I wonder why this was accepted ;)


> >  #ifdef CONFIG_KMEMCHECK
> >  	void *shadow;
> >  #endif
> > Index: mmotm-2.6.27-rc7+/mm/Makefile
> > ===================================================================
> > --- mmotm-2.6.27-rc7+.orig/mm/Makefile
> > +++ mmotm-2.6.27-rc7+/mm/Makefile
> > @@ -34,6 +34,6 @@ obj-$(CONFIG_FS_XIP) += filemap_xip.o
> >  obj-$(CONFIG_MIGRATION) += migrate.o
> >  obj-$(CONFIG_SMP) += allocpercpu.o
> >  obj-$(CONFIG_QUICKLIST) += quicklist.o
> > -obj-$(CONFIG_CGROUP_MEM_RES_CTLR) += memcontrol.o
> > +obj-$(CONFIG_CGROUP_MEM_RES_CTLR) += memcontrol.o page_cgroup.o
> >  obj-$(CONFIG_CGROUP_MEMRLIMIT_CTLR) += memrlimitcgroup.o
> >  obj-$(CONFIG_KMEMTRACE) += kmemtrace.o
> > Index: mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
> > ===================================================================
> > --- /dev/null
> > +++ mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
> > @@ -0,0 +1,90 @@
> > +#ifndef __LINUX_PAGE_CGROUP_H
> > +#define __LINUX_PAGE_CGROUP_H
> > +#include <linux/bit_spinlock.h>
> > +/*
> > + * Page Cgroup can be considered as an extended mem_map.
> > + * A page_cgroup page is associated with every page descriptor. The
> > + * page_cgroup helps us identify information about the cgroup
> > + * All page cgroups are allocated at boot or memory hotplug event,
> > + * then the page cgroup for pfn always exists.
> > + */
> > +struct page_cgroup {
> > +	unsigned long flags;
> > +	struct mem_cgroup *mem_cgroup;
> > +	struct page *page;
> > +	struct list_head lru;		/* per cgroup LRU list */
> > +};
> > +
> > +void __init pgdat_page_cgroup_init(struct pglist_data *pgdat);
> > +void __init page_cgroup_init(void);
> > +struct page_cgroup *lookup_page_cgroup(struct page *page);
> > +
> > +enum {
> > +	/* flags for mem_cgroup */
> > +	PCG_LOCK,  /* page cgroup is locked */
> > +	PCG_CACHE, /* charged as cache */
> > +	PCG_USED, /* this object is in use. */
> > +	/* flags for LRU placement */
> > +	PCG_ACTIVE, /* page is active in this cgroup */
> > +	PCG_FILE, /* page is file system backed */
> > +	PCG_UNEVICTABLE, /* page is unevictableable */
> > +};
> > +
> > +#define TESTPCGFLAG(uname, lname)			\
> > +static inline int PageCgroup##uname(struct page_cgroup *pc)	\
> > +	{ return test_bit(PCG_##lname, &pc->flags); }
> > +
> > +#define SETPCGFLAG(uname, lname)			\
> > +static inline void SetPageCgroup##uname(struct page_cgroup *pc)\
> > +	{ set_bit(PCG_##lname, &pc->flags);  }
> > +
> > +#define CLEARPCGFLAG(uname, lname)			\
> > +static inline void ClearPageCgroup##uname(struct page_cgroup *pc)	\
> > +	{ clear_bit(PCG_##lname, &pc->flags);  }
> > +
> > +/* Cache flag is set only once (at allocation) */
> > +TESTPCGFLAG(Cache, CACHE)
> > +
> > +TESTPCGFLAG(Used, USED)
> > +CLEARPCGFLAG(Used, USED)
> > +
> > +/* LRU management flags (from global-lru definition) */
> > +TESTPCGFLAG(File, FILE)
> > +SETPCGFLAG(File, FILE)
> > +CLEARPCGFLAG(File, FILE)
> > +
> > +TESTPCGFLAG(Active, ACTIVE)
> > +SETPCGFLAG(Active, ACTIVE)
> > +CLEARPCGFLAG(Active, ACTIVE)
> > +
> > +TESTPCGFLAG(Unevictable, UNEVICTABLE)
> > +SETPCGFLAG(Unevictable, UNEVICTABLE)
> > +CLEARPCGFLAG(Unevictable, UNEVICTABLE)
> > +
> 
> Can we make this patch indepedent of the flags changes and push it in ASAP.
> 
Need much work....Hmm..rewrite all again ? 


> > +static inline int page_cgroup_nid(struct page_cgroup *pc)
> > +{
> > +	return page_to_nid(pc->page);
> > +}
> > +
> > +static inline enum zone_type page_cgroup_zid(struct page_cgroup *pc)
> > +{
> > +	return page_zonenum(pc->page);
> > +}
> > +
> > +static inline void lock_page_cgroup(struct page_cgroup *pc)
> > +{
> > +	bit_spin_lock(PCG_LOCK, &pc->flags);
> > +}
> > +
> > +static inline int trylock_page_cgroup(struct page_cgroup *pc)
> > +{
> > +	return bit_spin_trylock(PCG_LOCK, &pc->flags);
> > +}
> > +
> > +static inline void unlock_page_cgroup(struct page_cgroup *pc)
> > +{
> > +	bit_spin_unlock(PCG_LOCK, &pc->flags);
> > +}
> > +
> > +
> > +#endif
> > Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
> > ===================================================================
> > --- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
> > +++ mmotm-2.6.27-rc7+/mm/memcontrol.c
> > @@ -35,11 +35,11 @@
> >  #include <linux/vmalloc.h>
> >  #include <linux/mm_inline.h>
> >  #include <linux/writeback.h>
> > +#include <linux/page_cgroup.h>
> > 
> >  #include <asm/uaccess.h>
> > 
> >  struct cgroup_subsys mem_cgroup_subsys __read_mostly;
> > -static struct kmem_cache *page_cgroup_cache __read_mostly;
> >  #define MEM_CGROUP_RECLAIM_RETRIES	5
> > 
> >  /*
> > @@ -139,80 +139,6 @@ static struct mem_cgroup init_mem_cgroup
> > 
> >  #define is_root_cgroup(cgrp)	((cgrp) == &init_mem_cgroup)
> > 
> > -
> > -/*
> > - * We use the lower bit of the page->page_cgroup pointer as a bit spin
> > - * lock.  We need to ensure that page->page_cgroup is at least two
> > - * byte aligned (based on comments from Nick Piggin).  But since
> > - * bit_spin_lock doesn't actually set that lock bit in a non-debug
> > - * uniprocessor kernel, we should avoid setting it here too.
> > - */
> > -#define PAGE_CGROUP_LOCK_BIT 	0x0
> > -#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
> > -#define PAGE_CGROUP_LOCK 	(1 << PAGE_CGROUP_LOCK_BIT)
> > -#else
> > -#define PAGE_CGROUP_LOCK	0x0
> > -#endif
> > -
> > -/*
> > - * A page_cgroup page is associated with every page descriptor. The
> > - * page_cgroup helps us identify information about the cgroup
> > - */
> > -struct page_cgroup {
> > -	struct list_head lru;		/* per cgroup LRU list */
> > -	struct page *page;
> > -	struct mem_cgroup *mem_cgroup;
> > -	unsigned long flags;
> > -};
> > -
> > -enum {
> > -	/* flags for mem_cgroup */
> > -	PCG_CACHE, /* charged as cache */
> > -	/* flags for LRU placement */
> > -	PCG_ACTIVE, /* page is active in this cgroup */
> > -	PCG_FILE, /* page is file system backed */
> > -	PCG_UNEVICTABLE, /* page is unevictableable */
> > -};
> > -
> > -#define TESTPCGFLAG(uname, lname)			\
> > -static inline int PageCgroup##uname(struct page_cgroup *pc)	\
> > -	{ return test_bit(PCG_##lname, &pc->flags); }
> > -
> > -#define SETPCGFLAG(uname, lname)			\
> > -static inline void SetPageCgroup##uname(struct page_cgroup *pc)\
> > -	{ set_bit(PCG_##lname, &pc->flags);  }
> > -
> > -#define CLEARPCGFLAG(uname, lname)			\
> > -static inline void ClearPageCgroup##uname(struct page_cgroup *pc)	\
> > -	{ clear_bit(PCG_##lname, &pc->flags);  }
> > -
> > -
> > -/* Cache flag is set only once (at allocation) */
> > -TESTPCGFLAG(Cache, CACHE)
> > -
> > -/* LRU management flags (from global-lru definition) */
> > -TESTPCGFLAG(File, FILE)
> > -SETPCGFLAG(File, FILE)
> > -CLEARPCGFLAG(File, FILE)
> > -
> > -TESTPCGFLAG(Active, ACTIVE)
> > -SETPCGFLAG(Active, ACTIVE)
> > -CLEARPCGFLAG(Active, ACTIVE)
> > -
> > -TESTPCGFLAG(Unevictable, UNEVICTABLE)
> > -SETPCGFLAG(Unevictable, UNEVICTABLE)
> > -CLEARPCGFLAG(Unevictable, UNEVICTABLE)
> > -
> > -static int page_cgroup_nid(struct page_cgroup *pc)
> > -{
> > -	return page_to_nid(pc->page);
> > -}
> > -
> > -static enum zone_type page_cgroup_zid(struct page_cgroup *pc)
> > -{
> > -	return page_zonenum(pc->page);
> > -}
> > -
> >  enum charge_type {
> >  	MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
> >  	MEM_CGROUP_CHARGE_TYPE_MAPPED,
> > @@ -223,9 +149,9 @@ enum charge_type {
> > 
> >  static const unsigned long
> >  pcg_default_flags[NR_CHARGE_TYPE] = {
> > -	((1 << PCG_CACHE) | (1 << PCG_FILE)),
> > -	((1 << PCG_ACTIVE)),
> > -	((1 << PCG_ACTIVE) | (1 << PCG_CACHE)),
> > +	(1 << PCG_CACHE) | (1 << PCG_FILE) | (1 << PCG_USED) | (1 << PCG_LOCK),
> > +	(1 << PCG_ACTIVE) | (1 << PCG_LOCK) | (1 << PCG_USED),
> > +	(1 << PCG_ACTIVE) | (1 << PCG_CACHE) | (1 << PCG_USED)|  (1 << PCG_LOCK),
> >  	0,
> >  };
> > 
> > @@ -308,37 +234,6 @@ struct mem_cgroup *mem_cgroup_from_task(
> >  				struct mem_cgroup, css);
> >  }
> > 
> > -static inline int page_cgroup_locked(struct page *page)
> > -{
> > -	return bit_spin_is_locked(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
> > -}
> > -
> > -static void page_assign_page_cgroup(struct page *page, struct page_cgroup *pc)
> > -{
> > -	VM_BUG_ON(!page_cgroup_locked(page));
> > -	page->page_cgroup = ((unsigned long)pc | PAGE_CGROUP_LOCK);
> > -}
> > -
> > -struct page_cgroup *page_get_page_cgroup(struct page *page)
> > -{
> > -	return (struct page_cgroup *) (page->page_cgroup & ~PAGE_CGROUP_LOCK);
> > -}
> > -
> > -static void lock_page_cgroup(struct page *page)
> > -{
> > -	bit_spin_lock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
> > -}
> > -
> > -static int try_lock_page_cgroup(struct page *page)
> > -{
> > -	return bit_spin_trylock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
> > -}
> > -
> > -static void unlock_page_cgroup(struct page *page)
> > -{
> > -	bit_spin_unlock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
> > -}
> > -
> >  static void __mem_cgroup_remove_list(struct mem_cgroup_per_zone *mz,
> >  			struct page_cgroup *pc)
> >  {
> > @@ -442,22 +337,19 @@ void mem_cgroup_move_lists(struct page *
> >  	 * safely get to page_cgroup without it, so just try_lock it:
> >  	 * mem_cgroup_isolate_pages allows for page left on wrong list.
> >  	 */
> > -	if (!try_lock_page_cgroup(page))
> > +	pc = lookup_page_cgroup(page);
> > +
> > +	if (!trylock_page_cgroup(pc))
> >  		return;
> > 
> > -	pc = page_get_page_cgroup(page);
> > -	if (pc) {
> > +	if (PageCgroupUsed(pc)) {
> >  		mem = pc->mem_cgroup;
> >  		mz = page_cgroup_zoneinfo(pc);
> >  		spin_lock_irqsave(&mz->lru_lock, flags);
> > -		/*
> > -		 * check against the race with move_account.
> > -		 */
> > -		if (likely(mem == pc->mem_cgroup))
> > -			__mem_cgroup_move_lists(pc, lru);
> > +		__mem_cgroup_move_lists(pc, lru);
> >  		spin_unlock_irqrestore(&mz->lru_lock, flags);
> >  	}
> > -	unlock_page_cgroup(page);
> > +	unlock_page_cgroup(pc);
> >  }
> > 
> >  /*
> > @@ -544,6 +436,8 @@ unsigned long mem_cgroup_isolate_pages(u
> >  	list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
> >  		if (scan >= nr_to_scan)
> >  			break;
> > +		if (unlikely(!PageCgroupUsed(pc)))
> > +			continue;
> >  		page = pc->page;
> > 
> >  		if (unlikely(!PageLRU(page)))
> > @@ -611,12 +505,12 @@ int mem_cgroup_move_account(struct page 
> >  		/* Now, we assume no_limit...no failure here. */
> >  		return ret;
> >  	}
> > -	if (!try_lock_page_cgroup(page)) {
> > +	if (!trylock_page_cgroup(pc)) {
> >  		res_counter_uncharge(&to->res, PAGE_SIZE);
> >  		return ret;
> >  	}
> > 
> > -	if (page_get_page_cgroup(page) != pc) {
> > +	if (!PageCgroupUsed(pc)) {
> >  		res_counter_uncharge(&to->res, PAGE_SIZE);
> >  		goto out;
> >  	}
> > @@ -634,7 +528,7 @@ int mem_cgroup_move_account(struct page 
> >  		res_counter_uncharge(&to->res, PAGE_SIZE);
> >  	}
> >  out:
> > -	unlock_page_cgroup(page);
> > +	unlock_page_cgroup(pc);
> > 
> >  	return ret;
> >  }
> > @@ -651,26 +545,27 @@ static int mem_cgroup_charge_common(stru
> >  {
> >  	struct mem_cgroup *mem;
> >  	struct page_cgroup *pc;
> > -	unsigned long flags;
> >  	unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
> >  	struct mem_cgroup_per_zone *mz;
> > +	unsigned long flags;
> > 
> > -	pc = kmem_cache_alloc(page_cgroup_cache, gfp_mask);
> > -	if (unlikely(pc == NULL))
> > -		goto err;
> > -
> > +	pc = lookup_page_cgroup(page);
> > +	/* can happen at boot */
> > +	if (unlikely(!pc))
> > +		return 0;
> > +	prefetchw(pc);
> >  	/*
> >  	 * We always charge the cgroup the mm_struct belongs to.
> >  	 * The mm_struct's mem_cgroup changes on task migration if the
> >  	 * thread group leader migrates. It's possible that mm is not
> >  	 * set, if so charge the init_mm (happens for pagecache usage).
> >  	 */
> > +
> >  	if (likely(!memcg)) {
> >  		rcu_read_lock();
> >  		mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
> >  		if (unlikely(!mem)) {
> >  			rcu_read_unlock();
> > -			kmem_cache_free(page_cgroup_cache, pc);
> >  			return 0;
> >  		}
> >  		/*
> > @@ -706,36 +601,34 @@ static int mem_cgroup_charge_common(stru
> >  		}
> >  	}
> > 
> > +	preempt_disable();
> 
> I don't understand the preempt_disable() is it for atomic operations? I would
> like to split the removal of struct page from atomic operations for performance.
> I think it will make it easier to merge/review.
> 
Memory hotremoval is not related to this.

This preempt_disable() is avoidance for deadlock. (I thought)

 lock_page_cgroup();
	-> spin_lock_irqsave(&mz->lru_lock);
	-> spin_unlock_irqrestore(&mz->lru_lock);
 unlock_page_cgroup();

After review, my current code drops this preempt_disable().



> > +	lock_page_cgroup(pc);
> > +	if (unlikely(PageCgroupUsed(pc))) {
> > +		unlock_page_cgroup(pc);
> > +		res_counter_uncharge(&mem->res, PAGE_SIZE);
> > +		css_put(&mem->css);
> > +		preempt_enable();
> > +		goto done;
> > +	}
> >  	pc->mem_cgroup = mem;
> > -	pc->page = page;
> >  	/*
> >  	 * If a page is accounted as a page cache, insert to inactive list.
> >  	 * If anon, insert to active list.
> >  	 */
> >  	pc->flags = pcg_default_flags[ctype];
> > 
> > -	lock_page_cgroup(page);
> > -	if (unlikely(page_get_page_cgroup(page))) {
> > -		unlock_page_cgroup(page);
> > -		res_counter_uncharge(&mem->res, PAGE_SIZE);
> > -		css_put(&mem->css);
> > -		kmem_cache_free(page_cgroup_cache, pc);
> > -		goto done;
> > -	}
> > -	page_assign_page_cgroup(page, pc);
> > -
> >  	mz = page_cgroup_zoneinfo(pc);
> > +
> >  	spin_lock_irqsave(&mz->lru_lock, flags);
> >  	__mem_cgroup_add_list(mz, pc);
> >  	spin_unlock_irqrestore(&mz->lru_lock, flags);
> > +	unlock_page_cgroup(pc);
> > +	preempt_enable();
> > 
> > -	unlock_page_cgroup(page);
> >  done:
> >  	return 0;
> >  out:
> >  	css_put(&mem->css);
> > -	kmem_cache_free(page_cgroup_cache, pc);
> > -err:
> >  	return -ENOMEM;
> >  }
> > 
> > @@ -743,7 +636,8 @@ int mem_cgroup_charge(struct page *page,
> >  {
> >  	if (mem_cgroup_subsys.disabled)
> >  		return 0;
> > -
> > +	if (PageCompound(page))
> > +		return 0;
> >  	/*
> >  	 * If already mapped, we don't have to account.
> >  	 * If page cache, page->mapping has address_space.
> > @@ -764,7 +658,8 @@ int mem_cgroup_cache_charge(struct page 
> >  {
> >  	if (mem_cgroup_subsys.disabled)
> >  		return 0;
> > -
> > +	if (PageCompound(page))
> > +		return 0;
> >  	/*
> >  	 * Corner case handling. This is called from add_to_page_cache()
> >  	 * in usual. But some FS (shmem) precharges this page before calling it
> > @@ -777,15 +672,16 @@ int mem_cgroup_cache_charge(struct page 
> >  	if (!(gfp_mask & __GFP_WAIT)) {
> >  		struct page_cgroup *pc;
> > 
> > -		lock_page_cgroup(page);
> > -		pc = page_get_page_cgroup(page);
> > -		if (pc) {
> > -			VM_BUG_ON(pc->page != page);
> > -			VM_BUG_ON(!pc->mem_cgroup);
> > -			unlock_page_cgroup(page);
> > +
> > +		pc = lookup_page_cgroup(page);
> > +		if (!pc)
> > +			return 0;
> > +		lock_page_cgroup(pc);
> > +		if (PageCgroupUsed(pc)) {
> > +			unlock_page_cgroup(pc);
> >  			return 0;
> >  		}
> > -		unlock_page_cgroup(page);
> > +		unlock_page_cgroup(pc);
> >  	}
> > 
> >  	if (unlikely(!mm))
> > @@ -812,49 +708,41 @@ __mem_cgroup_uncharge_common(struct page
> > 
> >  	if (mem_cgroup_subsys.disabled)
> >  		return;
> > +	/* check the condition we can know from page */
> > 
> > -	/*
> > -	 * Check if our page_cgroup is valid
> > -	 */
> > -	lock_page_cgroup(page);
> > -	pc = page_get_page_cgroup(page);
> > -	if (unlikely(!pc))
> > -		goto unlock;
> > -
> > -	VM_BUG_ON(pc->page != page);
> > +	pc = lookup_page_cgroup(page);
> > +	if (unlikely(!pc || !PageCgroupUsed(pc)))
> > +		return;
> > +	preempt_disable();
> > +	lock_page_cgroup(pc);
> > +	if (unlikely(page_mapped(page))) {
> > +		unlock_page_cgroup(pc);
> > +		preempt_enable();
> > +		return;
> > +	}
> > +	ClearPageCgroupUsed(pc);
> > +	unlock_page_cgroup(pc);
> > 
> > -	if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
> > -	    && ((PageCgroupCache(pc) || page_mapped(page))))
> > -		goto unlock;
> > -retry:
> >  	mem = pc->mem_cgroup;
> >  	mz = page_cgroup_zoneinfo(pc);
> > +
> >  	spin_lock_irqsave(&mz->lru_lock, flags);
> > -	if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED &&
> > -	    unlikely(mem != pc->mem_cgroup)) {
> > -		/* MAPPED account can be done without lock_page().
> > -		   Check race with mem_cgroup_move_account() */
> > -		spin_unlock_irqrestore(&mz->lru_lock, flags);
> > -		goto retry;
> > -	}
> >  	__mem_cgroup_remove_list(mz, pc);
> >  	spin_unlock_irqrestore(&mz->lru_lock, flags);
> > -
> > -	page_assign_page_cgroup(page, NULL);
> > -	unlock_page_cgroup(page);
> > -
> > -
> > -	res_counter_uncharge(&mem->res, PAGE_SIZE);
> > +	pc->mem_cgroup = NULL;
> >  	css_put(&mem->css);
> > +	preempt_enable();
> > +	res_counter_uncharge(&mem->res, PAGE_SIZE);
> > 
> > -	kmem_cache_free(page_cgroup_cache, pc);
> >  	return;
> > -unlock:
> > -	unlock_page_cgroup(page);
> >  }
> > 
> >  void mem_cgroup_uncharge_page(struct page *page)
> >  {
> > +	if (page_mapped(page))
> > +		return;
> > +	if (page->mapping && !PageAnon(page))
> > +		return;
> >  	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
> >  }
> > 
> > @@ -878,9 +766,9 @@ int mem_cgroup_prepare_migration(struct 
> >  	if (mem_cgroup_subsys.disabled)
> >  		return 0;
> > 
> > -	lock_page_cgroup(page);
> > -	pc = page_get_page_cgroup(page);
> > -	if (pc) {
> > +	pc = lookup_page_cgroup(page);
> > +	lock_page_cgroup(pc);
> > +	if (PageCgroupUsed(pc)) {
> >  		mem = pc->mem_cgroup;
> >  		css_get(&mem->css);
> >  		if (PageCgroupCache(pc)) {
> > @@ -890,7 +778,7 @@ int mem_cgroup_prepare_migration(struct 
> >  				ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
> >  		}
> >  	}
> > -	unlock_page_cgroup(page);
> > +	unlock_page_cgroup(pc);
> >  	if (mem) {
> >  		ret = mem_cgroup_charge_common(newpage, NULL, GFP_KERNEL,
> >  			ctype, mem);
> > @@ -997,6 +885,8 @@ static void mem_cgroup_force_empty_list(
> >  	spin_lock_irqsave(&mz->lru_lock, flags);
> >  	list_for_each_entry_safe(pc, tmp, list, lru) {
> >  		page = pc->page;
> > +		if (!PageCgroupUsed(pc))
> > +			continue;
> >  		/* For avoiding race with speculative page cache handling. */
> >  		if (!PageLRU(page) || !get_page_unless_zero(page)) {
> >  			continue;
> > @@ -1270,8 +1160,8 @@ mem_cgroup_create(struct cgroup_subsys *
> >  	int node;
> > 
> >  	if (unlikely((cont->parent) == NULL)) {
> > +		page_cgroup_init();
> >  		mem = &init_mem_cgroup;
> > -		page_cgroup_cache = KMEM_CACHE(page_cgroup, SLAB_PANIC);
> >  	} else {
> >  		mem = mem_cgroup_alloc();
> >  		if (!mem)
> > Index: mmotm-2.6.27-rc7+/mm/page_alloc.c
> > ===================================================================
> > --- mmotm-2.6.27-rc7+.orig/mm/page_alloc.c
> > +++ mmotm-2.6.27-rc7+/mm/page_alloc.c
> > @@ -44,7 +44,7 @@
> >  #include <linux/backing-dev.h>
> >  #include <linux/fault-inject.h>
> >  #include <linux/page-isolation.h>
> > -#include <linux/memcontrol.h>
> > +#include <linux/page_cgroup.h>
> >  #include <linux/debugobjects.h>
> > 
> >  #include <asm/tlbflush.h>
> > @@ -223,17 +223,12 @@ static inline int bad_range(struct zone 
> > 
> >  static void bad_page(struct page *page)
> >  {
> > -	void *pc = page_get_page_cgroup(page);
> > -
> >  	printk(KERN_EMERG "Bad page state in process '%s'\n" KERN_EMERG
> >  		"page:%p flags:0x%0*lx mapping:%p mapcount:%d count:%d\n",
> >  		current->comm, page, (int)(2*sizeof(unsigned long)),
> >  		(unsigned long)page->flags, page->mapping,
> >  		page_mapcount(page), page_count(page));
> > -	if (pc) {
> > -		printk(KERN_EMERG "cgroup:%p\n", pc);
> > -		page_reset_bad_cgroup(page);
> > -	}
> > +
> >  	printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n"
> >  		KERN_EMERG "Backtrace:\n");
> >  	dump_stack();
> > @@ -472,7 +467,6 @@ static inline void free_pages_check(stru
> >  	free_page_mlock(page);
> >  	if (unlikely(page_mapcount(page) |
> >  		(page->mapping != NULL)  |
> > -		(page_get_page_cgroup(page) != NULL) |
> >  		(page_count(page) != 0)  |
> >  		(page->flags & PAGE_FLAGS_CHECK_AT_FREE)))
> >  		bad_page(page);
> > @@ -609,7 +603,6 @@ static void prep_new_page(struct page *p
> >  {
> >  	if (unlikely(page_mapcount(page) |
> >  		(page->mapping != NULL)  |
> > -		(page_get_page_cgroup(page) != NULL) |
> >  		(page_count(page) != 0)  |
> >  		(page->flags & PAGE_FLAGS_CHECK_AT_PREP)))
> >  		bad_page(page);
> > @@ -3495,6 +3488,7 @@ static void __paginginit free_area_init_
> >  	pgdat->nr_zones = 0;
> >  	init_waitqueue_head(&pgdat->kswapd_wait);
> >  	pgdat->kswapd_max_order = 0;
> > +	pgdat_page_cgroup_init(pgdat);
> >  	
> >  	for (j = 0; j < MAX_NR_ZONES; j++) {
> >  		struct zone *zone = pgdat->node_zones + j;
> > Index: mmotm-2.6.27-rc7+/include/linux/mmzone.h
> > ===================================================================
> > --- mmotm-2.6.27-rc7+.orig/include/linux/mmzone.h
> > +++ mmotm-2.6.27-rc7+/include/linux/mmzone.h
> > @@ -604,6 +604,9 @@ typedef struct pglist_data {
> >  	int nr_zones;
> >  #ifdef CONFIG_FLAT_NODE_MEM_MAP
> >  	struct page *node_mem_map;
> > +#ifdef CONFIG_CGROUP_MEM_RES_CTLR
> > +	struct page_cgroup *node_page_cgroup;
> > +#endif
> >  #endif
> >  	struct bootmem_data *bdata;
> >  #ifdef CONFIG_MEMORY_HOTPLUG
> > @@ -932,6 +935,7 @@ static inline unsigned long early_pfn_to
> >  #endif
> > 
> >  struct page;
> > +struct page_cgroup;
> >  struct mem_section {
> >  	/*
> >  	 * This is, logically, a pointer to an array of struct
> > @@ -949,6 +953,11 @@ struct mem_section {
> > 
> >  	/* See declaration of similar field in struct zone */
> >  	unsigned long *pageblock_flags;
> > +#ifdef CONFIG_CGROUP_MEM_RES_CTLR
> > +	/* see page_cgroup.h */
> > +	struct page_cgroup *page_cgroup;
> > +	unsigned long pad;
> > +#endif
> >  };
> > 
> >  #ifdef CONFIG_SPARSEMEM_EXTREME
> > Index: mmotm-2.6.27-rc7+/include/linux/memcontrol.h
> > ===================================================================
> > --- mmotm-2.6.27-rc7+.orig/include/linux/memcontrol.h
> > +++ mmotm-2.6.27-rc7+/include/linux/memcontrol.h
> > @@ -29,7 +29,6 @@ struct mm_struct;
> > 
> >  #define page_reset_bad_cgroup(page)	((page)->page_cgroup = 0)
> > 
> > -extern struct page_cgroup *page_get_page_cgroup(struct page *page);
> >  extern int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
> >  				gfp_t gfp_mask);
> >  extern int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
> > @@ -72,16 +71,8 @@ extern void mem_cgroup_record_reclaim_pr
> >  extern long mem_cgroup_calc_reclaim(struct mem_cgroup *mem, struct zone *zone,
> >  					int priority, enum lru_list lru);
> > 
> > -#else /* CONFIG_CGROUP_MEM_RES_CTLR */
> > -static inline void page_reset_bad_cgroup(struct page *page)
> > -{
> > -}
> > -
> > -static inline struct page_cgroup *page_get_page_cgroup(struct page *page)
> > -{
> > -	return NULL;
> > -}
> > 
> > +#else /* CONFIG_CGROUP_MEM_RES_CTLR */
> >  static inline int mem_cgroup_charge(struct page *page,
> >  					struct mm_struct *mm, gfp_t gfp_mask)
> >  {
> > 
> 
> Except for the the performance changes for atomic operations, I like this patch
> very much.
> 
Did you see performance regression by atomic ops ?

I'll rewrite the whole stack from now for your request. 

Thanks,
-Kame

> For the page removal portions
> Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> as a co-maintainer
> 
> 
> -- 
> 	Balbir
> 

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> On Wed, 01 Oct 2008 09:33:53 +0530
> Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> 
>> Can we make this patch indepedent of the flags changes and push it in ASAP.
>>
> Need much work....Hmm..rewrite all again ? 
> 

I don't think you'll need to do a major rewrite? Will you? My concern is that
this patch does too much to be a single patch. Consider someone trying to do a
git-bisect to identify a problem? It is hard to review as well and I think the
patch that just removes struct page member can go in faster.

It will be easier to test/debug as well, we'll know if the problem is because of
new page_cgroup being outside struct page rather then guessing if it was the
atomic ops that caused the problem.

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[KAMEZAWA Hiroyuki]

On Wed, 01 Oct 2008 11:00:42 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> KAMEZAWA Hiroyuki wrote:
> > On Wed, 01 Oct 2008 09:33:53 +0530
> > Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> > 
> >> Can we make this patch indepedent of the flags changes and push it in ASAP.
> >>
> > Need much work....Hmm..rewrite all again ? 
> > 
> 
> I don't think you'll need to do a major rewrite? Will you? 
yes. LOCK bit is on page_cgroup->flags bit.
Then, I'll check all places which modify page_cgroup->flags again and
take lock always.
This means I'll have to check dead-lock and preemption and irq-disable, again.

> My concern is that this patch does too much to be a single patch.
> Consider someone trying to do a
> git-bisect to identify a problem? It is hard to review as well and I think the
> patch that just removes struct page member can go in faster.
> 
Please apply atomic_flags first. this later.

> It will be easier to test/debug as well, we'll know if the problem is because of
> new page_cgroup being outside struct page rather then guessing if it was the
> atomic ops that caused the problem.
> 

atomic_ops patch just rewrite exisiting behavior.

Thanks,
-Kame

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[KAMEZAWA Hiroyuki]

On Wed, 1 Oct 2008 14:41:50 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> > It will be easier to test/debug as well, we'll know if the problem is because of
> > new page_cgroup being outside struct page rather then guessing if it was the
> > atomic ops that caused the problem.
> > 
> 
> atomic_ops patch just rewrite exisiting behavior.
> 
please forgive me to post v6 today, which passed 24h+ tests.
v5 is a week old.
Discussion about patch order is welcome. But please give me hint.

Thanks,
-Kame

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> On Wed, 1 Oct 2008 14:41:50 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> 
>>> It will be easier to test/debug as well, we'll know if the problem is because of
>>> new page_cgroup being outside struct page rather then guessing if it was the
>>> atomic ops that caused the problem.
>>>
>> atomic_ops patch just rewrite exisiting behavior.
>>
> please forgive me to post v6 today, which passed 24h+ tests.
> v5 is a week old.
> Discussion about patch order is welcome. But please give me hint.

That sounds impressive. I'll test and review v6.

-- 
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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[KAMEZAWA Hiroyuki]

On Wed, 1 Oct 2008 14:07:48 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > Can we make this patch indepedent of the flags changes and push it in ASAP.
> > 
> Need much work....Hmm..rewrite all again ? 
> 

BTW, do you have good idea to modify flag bit without affecting LOCK bit on
page_cgroup->flags ?

At least, we'll have to set ACTIVE/INACTIVE/UNEVICTABLE flags dynamically.
take lock_page_cgroup() always ?
__mem_cgroup_move_lists() will have some amount of changes. And we should
check dead lock again.

Thanks,
-Kame

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> On Wed, 1 Oct 2008 14:07:48 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
>>> Can we make this patch indepedent of the flags changes and push it in ASAP.
>>>
>> Need much work....Hmm..rewrite all again ? 
>>
> 
> BTW, do you have good idea to modify flag bit without affecting LOCK bit on
> page_cgroup->flags ?
> 
> At least, we'll have to set ACTIVE/INACTIVE/UNEVICTABLE flags dynamically.
> take lock_page_cgroup() always ?

In the past patches, I've used lock_page_cgroup(). In some cases like
initialization at boot time, I've ignored taking the lock, since I know no-one
is accessing them yet.

> __mem_cgroup_move_lists() will have some amount of changes. And we should
> check dead lock again.

__mem_cgroup_move_lists() is called from mem_cgroup_isolate_pages() and
mem_cgroup_move_lists(). In mem_cgroup_move_lists(), we have the page_cgroup
lock. I think the current code works on the assumption (although not documented
anywhere I've seen), that PAGE_CGROUP_FLAG_INACTIVE/ACTIVE/UNEVICTABLE bits are
protected by lru_lock. Please look at

__mem_cgroup_remove_list
__mem_cgroup_add_list
__mem_cgroup_move_lists
__mem_cgroup_charge_common (sets this flag, before the pc is associated with the
page).

Am I missing something (today is holiday here, so I am in a bit of a lazy/sleepy
mood :) )

-- 
	Balbir

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Re: [PATCH 9/12] memcg allocate all page_cgroup at boot

[KAMEZAWA Hiroyuki]

On Wed, 01 Oct 2008 11:29:04 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> > __mem_cgroup_move_lists() will have some amount of changes. And we should
> > check dead lock again.
> 
> __mem_cgroup_move_lists() is called from mem_cgroup_isolate_pages() and
> mem_cgroup_move_lists(). In mem_cgroup_move_lists(), we have the page_cgroup
> lock. I think the current code works on the assumption (although not documented
> anywhere I've seen), that PAGE_CGROUP_FLAG_INACTIVE/ACTIVE/UNEVICTABLE bits are
> protected by lru_lock. Please look at
yes, I wrote them.

> 
> __mem_cgroup_remove_list
> __mem_cgroup_add_list
> __mem_cgroup_move_lists
> __mem_cgroup_charge_common (sets this flag, before the pc is associated with the
> page).
> 
But my point is lru_lock doesn't means page_cgroup is not locked by someone and
we must take always lock_page_cgroup() when we modify flags.

Then, mem_cgroup_isolate_page() should have to take lock.
But this means we have to care preemption for avoiding deadlock.
Maybe need some time to test.

Thanks,
-Kame

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[PATCH 10/12] memcg free page_cgroup from LRU in lazy

[KAMEZAWA Hiroyuki]

Free page_cgroup from its LRU in batched manner.

When uncharge() is called, page is pushed onto per-cpu vector and
removed from LRU, later.. This routine resembles to global LRU's pagevec.
This patch is half of the whole patch and a set with following lazy LRU add
patch.


Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 mm/memcontrol.c |  164 +++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 152 insertions(+), 12 deletions(-)

Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -36,6 +36,7 @@
 #include <linux/mm_inline.h>
 #include <linux/writeback.h>
 #include <linux/page_cgroup.h>
+#include <linux/cpu.h>
 
 #include <asm/uaccess.h>
 
@@ -533,6 +534,116 @@ out:
 	return ret;
 }
 
+
+#define MEMCG_PCPVEC_SIZE	(14)	/* size of pagevec */
+struct memcg_percpu_vec {
+	int nr;
+	int limit;
+	struct page_cgroup *vec[MEMCG_PCPVEC_SIZE];
+};
+static DEFINE_PER_CPU(struct memcg_percpu_vec, memcg_free_vec);
+
+static void
+__release_page_cgroup(struct memcg_percpu_vec *mpv)
+{
+	unsigned long flags;
+	struct mem_cgroup_per_zone *mz, *prev_mz;
+	struct page_cgroup *pc;
+	int i, nr;
+
+	local_irq_save(flags);
+	nr = mpv->nr;
+	mpv->nr = 0;
+	prev_mz = NULL;
+	for (i = nr - 1; i >= 0; i--) {
+		pc = mpv->vec[i];
+		VM_BUG_ON(PageCgroupUsed(pc));
+		mz = page_cgroup_zoneinfo(pc);
+		if (prev_mz != mz) {
+			if (prev_mz)
+				spin_unlock(&prev_mz->lru_lock);
+			prev_mz = mz;
+			spin_lock(&mz->lru_lock);
+		}
+		__mem_cgroup_remove_list(mz, pc);
+		css_put(&pc->mem_cgroup->css);
+		pc->mem_cgroup = NULL;
+	}
+	if (prev_mz)
+		spin_unlock(&prev_mz->lru_lock);
+	local_irq_restore(flags);
+
+}
+
+static void
+release_page_cgroup(struct page_cgroup *pc)
+{
+	struct memcg_percpu_vec *mpv;
+
+	mpv = &get_cpu_var(memcg_free_vec);
+	mpv->vec[mpv->nr++] = pc;
+	if (mpv->nr >= mpv->limit)
+		__release_page_cgroup(mpv);
+	put_cpu_var(memcg_free_vec);
+}
+
+static void page_cgroup_start_cache_cpu(int cpu)
+{
+	struct memcg_percpu_vec *mpv;
+	mpv = &per_cpu(memcg_free_vec, cpu);
+	mpv->limit = MEMCG_PCPVEC_SIZE;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void page_cgroup_stop_cache_cpu(int cpu)
+{
+	struct memcg_percpu_vec *mpv;
+	mpv = &per_cpu(memcg_free_vec, cpu);
+	mpv->limit = 0;
+}
+#endif
+
+
+/*
+ * Used when freeing memory resource controller to remove all
+ * page_cgroup (in obsolete list).
+ */
+static DEFINE_MUTEX(memcg_force_drain_mutex);
+
+static void drain_page_cgroup_local(struct work_struct *work)
+{
+	struct memcg_percpu_vec *mpv;
+	mpv = &get_cpu_var(memcg_free_vec);
+	__release_page_cgroup(mpv);
+	put_cpu_var(mpv);
+}
+
+static void drain_page_cgroup_cpu(int cpu)
+{
+	int local_cpu;
+	struct work_struct work;
+
+	local_cpu = get_cpu();
+	if (local_cpu == cpu) {
+		drain_page_cgroup_local(NULL);
+		put_cpu();
+		return;
+	}
+	put_cpu();
+
+	INIT_WORK(&work, drain_page_cgroup_local);
+	schedule_work_on(cpu, &work);
+	flush_work(&work);
+}
+
+static void drain_page_cgroup_all(void)
+{
+	mutex_lock(&memcg_force_drain_mutex);
+	schedule_on_each_cpu(drain_page_cgroup_local);
+	mutex_unlock(&memcg_force_drain_mutex);
+}
+
+
 /*
  * Charge the memory controller for page usage.
  * Return
@@ -703,8 +814,6 @@ __mem_cgroup_uncharge_common(struct page
 {
 	struct page_cgroup *pc;
 	struct mem_cgroup *mem;
-	struct mem_cgroup_per_zone *mz;
-	unsigned long flags;
 
 	if (mem_cgroup_subsys.disabled)
 		return;
@@ -722,16 +831,10 @@ __mem_cgroup_uncharge_common(struct page
 	}
 	ClearPageCgroupUsed(pc);
 	unlock_page_cgroup(pc);
+	preempt_enable();
 
 	mem = pc->mem_cgroup;
-	mz = page_cgroup_zoneinfo(pc);
-
-	spin_lock_irqsave(&mz->lru_lock, flags);
-	__mem_cgroup_remove_list(mz, pc);
-	spin_unlock_irqrestore(&mz->lru_lock, flags);
-	pc->mem_cgroup = NULL;
-	css_put(&mem->css);
-	preempt_enable();
+	release_page_cgroup(pc);
 	res_counter_uncharge(&mem->res, PAGE_SIZE);
 
 	return;
@@ -888,9 +991,8 @@ static void mem_cgroup_force_empty_list(
 		if (!PageCgroupUsed(pc))
 			continue;
 		/* For avoiding race with speculative page cache handling. */
-		if (!PageLRU(page) || !get_page_unless_zero(page)) {
+		if (!PageLRU(page) || !get_page_unless_zero(page))
 			continue;
-		}
 		mem_cgroup_move_account(page, pc, mem, &init_mem_cgroup);
 		put_page(page);
 		if (atomic_read(&mem->css.cgroup->count) > 0)
@@ -927,8 +1029,10 @@ static int mem_cgroup_force_empty(struct
 		 * While walking our own LRU, we also checks LRU bit on page.
 		 * If a page is on pagevec, it's not on LRU and we cannot
 		 * grab it. Calling lru_add_drain_all() here.
+		 * memory cgroup's its own vector shold be flushed, too.
 		 */
 		lru_add_drain_all();
+		drain_page_cgroup_all();
 		for_each_node_state(node, N_HIGH_MEMORY) {
 			for (zid = 0; zid < MAX_NR_ZONES; zid++) {
 				mz = mem_cgroup_zoneinfo(mem, node, zid);
@@ -1152,6 +1256,38 @@ static void mem_cgroup_free(struct mem_c
 		vfree(mem);
 }
 
+static void mem_cgroup_init_pcp(int cpu)
+{
+	page_cgroup_start_cache_cpu(cpu);
+}
+
+static int cpu_memcgroup_callback(struct notifier_block *nb,
+			unsigned long action, void *hcpu)
+{
+	int cpu = (long)hcpu;
+
+	switch(action) {
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		mem_cgroup_init_pcp(cpu);
+		break;
+#ifdef CONFIG_HOTPLUG_CPU
+	case CPU_DOWN_PREPARE:
+	case CPU_DOWN_PREPARE_FROZEN:
+		page_cgroup_stop_cache_cpu(cpu);
+		drain_page_cgroup_cpu(cpu);
+		break;
+#endif
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block __refdata memcgroup_nb =
+{
+	.notifier_call = cpu_memcgroup_callback,
+};
 
 static struct cgroup_subsys_state *
 mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
@@ -1162,6 +1298,10 @@ mem_cgroup_create(struct cgroup_subsys *
 	if (unlikely((cont->parent) == NULL)) {
 		page_cgroup_init();
 		mem = &init_mem_cgroup;
+		cpu_memcgroup_callback(&memcgroup_nb,
+					(unsigned long)CPU_UP_PREPARE,
+					(void *)(long)smp_processor_id());
+		register_hotcpu_notifier(&memcgroup_nb);
 	} else {
 		mem = mem_cgroup_alloc();
 		if (!mem)

[PATCH 11/12] memcg add to LRU in lazy

[KAMEZAWA Hiroyuki]

Delaying add_to_lru() and do it in batched manner like page_vec.
For doing that 2 flags PCG_USED and PCG_LRU.

If PCG_LRU is set, page is on LRU. It safe to access LRU via page_cgroup.
(under some lock.)

For avoiding race, this patch uses TestSetPageCgroupUsed().
and checking PCG_USED bit and PCG_LRU bit in add/free vector.
By this, lock_page_cgroup() in mem_cgroup_charge() is removed.

(I don't want to call lock_page_cgroup() under mz->lru_lock when 
 add/free vector core logic. So, TestSetPageCgroupUsed() logic is added.
 This TestSet is an easy way to avoid unneccesary nest of locks.)


Changelog: v3 -> v5.
 - removed css_get/put per page_cgroup struct.
   Now, new force_empty checks there is page_cgroup on the memcg.
   We don't need to be afraid of leak.

Changelog: v2 -> v3
 - added TRANSIT flag and removed lock from core logic.
Changelog: v1 -> v2:
 - renamed function name from use_page_cgroup to set_page_cgroup_lru().

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 include/linux/page_cgroup.h |   10 +++
 mm/memcontrol.c             |  121 +++++++++++++++++++++++++++++++-------------
 2 files changed, 96 insertions(+), 35 deletions(-)

Index: mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
===================================================================
--- mmotm-2.6.27-rc7+.orig/include/linux/page_cgroup.h
+++ mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
@@ -24,6 +24,7 @@ enum {
 	PCG_LOCK,  /* page cgroup is locked */
 	PCG_CACHE, /* charged as cache */
 	PCG_USED, /* this object is in use. */
+	PCG_LRU, /* this is on LRU */
 	/* flags for LRU placement */
 	PCG_ACTIVE, /* page is active in this cgroup */
 	PCG_FILE, /* page is file system backed */
@@ -42,11 +43,20 @@ static inline void SetPageCgroup##uname(
 static inline void ClearPageCgroup##uname(struct page_cgroup *pc)	\
 	{ clear_bit(PCG_##lname, &pc->flags);  }
 
+#define TESTSETPCGFLAG(uname, lname)\
+static inline int TestSetPageCgroup##uname(struct page_cgroup *pc)	\
+	{ return test_and_set_bit(PCG_##lname, &pc->flags);  }
+
 /* Cache flag is set only once (at allocation) */
 TESTPCGFLAG(Cache, CACHE)
 
 TESTPCGFLAG(Used, USED)
 CLEARPCGFLAG(Used, USED)
+TESTSETPCGFLAG(Used, USED)
+
+TESTPCGFLAG(LRU, LRU)
+SETPCGFLAG(LRU, LRU)
+CLEARPCGFLAG(LRU, LRU)
 
 /* LRU management flags (from global-lru definition) */
 TESTPCGFLAG(File, FILE)
Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -150,9 +150,9 @@ enum charge_type {
 
 static const unsigned long
 pcg_default_flags[NR_CHARGE_TYPE] = {
-	(1 << PCG_CACHE) | (1 << PCG_FILE) | (1 << PCG_USED) | (1 << PCG_LOCK),
-	(1 << PCG_ACTIVE) | (1 << PCG_LOCK) | (1 << PCG_USED),
-	(1 << PCG_ACTIVE) | (1 << PCG_CACHE) | (1 << PCG_USED)|  (1 << PCG_LOCK),
+	(1 << PCG_CACHE) | (1 << PCG_FILE) | (1 << PCG_USED),
+	(1 << PCG_ACTIVE) | (1 << PCG_USED),
+	(1 << PCG_ACTIVE) | (1 << PCG_CACHE) | (1 << PCG_USED),
 	0,
 };
 
@@ -195,7 +195,6 @@ page_cgroup_zoneinfo(struct page_cgroup 
 	struct mem_cgroup *mem = pc->mem_cgroup;
 	int nid = page_cgroup_nid(pc);
 	int zid = page_cgroup_zid(pc);
-
 	return mem_cgroup_zoneinfo(mem, nid, zid);
 }
 
@@ -343,7 +342,7 @@ void mem_cgroup_move_lists(struct page *
 	if (!trylock_page_cgroup(pc))
 		return;
 
-	if (PageCgroupUsed(pc)) {
+	if (PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
 		mem = pc->mem_cgroup;
 		mz = page_cgroup_zoneinfo(pc);
 		spin_lock_irqsave(&mz->lru_lock, flags);
@@ -502,6 +501,9 @@ int mem_cgroup_move_account(struct page 
 	from_mz =  mem_cgroup_zoneinfo(from, nid, zid);
 	to_mz =  mem_cgroup_zoneinfo(to, nid, zid);
 
+	if (!PageCgroupLRU(pc))
+		return ret;
+
 	if (res_counter_charge(&to->res, PAGE_SIZE)) {
 		/* Now, we assume no_limit...no failure here. */
 		return ret;
@@ -518,10 +520,8 @@ int mem_cgroup_move_account(struct page 
 
 	if (spin_trylock(&to_mz->lru_lock)) {
 		__mem_cgroup_remove_list(from_mz, pc);
-		css_put(&from->css);
 		res_counter_uncharge(&from->res, PAGE_SIZE);
 		pc->mem_cgroup = to;
-		css_get(&to->css);
 		__mem_cgroup_add_list(to_mz, pc);
 		ret = 0;
 		spin_unlock(&to_mz->lru_lock);
@@ -542,6 +542,7 @@ struct memcg_percpu_vec {
 	struct page_cgroup *vec[MEMCG_PCPVEC_SIZE];
 };
 static DEFINE_PER_CPU(struct memcg_percpu_vec, memcg_free_vec);
+static DEFINE_PER_CPU(struct memcg_percpu_vec, memcg_add_vec);
 
 static void
 __release_page_cgroup(struct memcg_percpu_vec *mpv)
@@ -557,7 +558,6 @@ __release_page_cgroup(struct memcg_percp
 	prev_mz = NULL;
 	for (i = nr - 1; i >= 0; i--) {
 		pc = mpv->vec[i];
-		VM_BUG_ON(PageCgroupUsed(pc));
 		mz = page_cgroup_zoneinfo(pc);
 		if (prev_mz != mz) {
 			if (prev_mz)
@@ -565,9 +565,10 @@ __release_page_cgroup(struct memcg_percp
 			prev_mz = mz;
 			spin_lock(&mz->lru_lock);
 		}
-		__mem_cgroup_remove_list(mz, pc);
-		css_put(&pc->mem_cgroup->css);
-		pc->mem_cgroup = NULL;
+		if (!PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
+			__mem_cgroup_remove_list(mz, pc);
+			ClearPageCgroupLRU(pc);
+		}
 	}
 	if (prev_mz)
 		spin_unlock(&prev_mz->lru_lock);
@@ -576,10 +577,43 @@ __release_page_cgroup(struct memcg_percp
 }
 
 static void
+__set_page_cgroup_lru(struct memcg_percpu_vec *mpv)
+{
+	unsigned long flags;
+	struct mem_cgroup_per_zone *mz, *prev_mz;
+	struct page_cgroup *pc;
+	int i, nr;
+
+	local_irq_save(flags);
+	nr = mpv->nr;
+	mpv->nr = 0;
+	prev_mz = NULL;
+
+	for (i = nr - 1; i >= 0; i--) {
+		pc = mpv->vec[i];
+		mz = page_cgroup_zoneinfo(pc);
+		if (prev_mz != mz) {
+			if (prev_mz)
+				spin_unlock(&prev_mz->lru_lock);
+			prev_mz = mz;
+			spin_lock(&mz->lru_lock);
+		}
+		if (PageCgroupUsed(pc) && !PageCgroupLRU(pc)) {
+			SetPageCgroupLRU(pc);
+			__mem_cgroup_add_list(mz, pc);
+		}
+	}
+
+	if (prev_mz)
+		spin_unlock(&prev_mz->lru_lock);
+	local_irq_restore(flags);
+
+}
+
+static void
 release_page_cgroup(struct page_cgroup *pc)
 {
 	struct memcg_percpu_vec *mpv;
-
 	mpv = &get_cpu_var(memcg_free_vec);
 	mpv->vec[mpv->nr++] = pc;
 	if (mpv->nr >= mpv->limit)
@@ -587,11 +621,25 @@ release_page_cgroup(struct page_cgroup *
 	put_cpu_var(memcg_free_vec);
 }
 
+static void
+set_page_cgroup_lru(struct page_cgroup *pc)
+{
+	struct memcg_percpu_vec *mpv;
+
+	mpv = &get_cpu_var(memcg_add_vec);
+	mpv->vec[mpv->nr++] = pc;
+	if (mpv->nr >= mpv->limit)
+		__set_page_cgroup_lru(mpv);
+	put_cpu_var(memcg_add_vec);
+}
+
 static void page_cgroup_start_cache_cpu(int cpu)
 {
 	struct memcg_percpu_vec *mpv;
 	mpv = &per_cpu(memcg_free_vec, cpu);
 	mpv->limit = MEMCG_PCPVEC_SIZE;
+	mpv = &per_cpu(memcg_add_vec, cpu);
+	mpv->limit = MEMCG_PCPVEC_SIZE;
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -600,6 +648,8 @@ static void page_cgroup_stop_cache_cpu(i
 	struct memcg_percpu_vec *mpv;
 	mpv = &per_cpu(memcg_free_vec, cpu);
 	mpv->limit = 0;
+	mpv = &per_cpu(memcg_add_vec, cpu);
+	mpv->limit = 0;
 }
 #endif
 
@@ -613,6 +663,9 @@ static DEFINE_MUTEX(memcg_force_drain_mu
 static void drain_page_cgroup_local(struct work_struct *work)
 {
 	struct memcg_percpu_vec *mpv;
+	mpv = &get_cpu_var(memcg_add_vec);
+	__set_page_cgroup_lru(mpv);
+	put_cpu_var(mpv);
 	mpv = &get_cpu_var(memcg_free_vec);
 	__release_page_cgroup(mpv);
 	put_cpu_var(mpv);
@@ -679,14 +732,9 @@ static int mem_cgroup_charge_common(stru
 			rcu_read_unlock();
 			return 0;
 		}
-		/*
-		 * For every charge from the cgroup, increment reference count
-		 */
-		css_get(&mem->css);
 		rcu_read_unlock();
 	} else {
 		mem = memcg;
-		css_get(&memcg->css);
 	}
 
 	while (unlikely(res_counter_charge(&mem->res, PAGE_SIZE))) {
@@ -713,33 +761,36 @@ static int mem_cgroup_charge_common(stru
 	}
 
 	preempt_disable();
-	lock_page_cgroup(pc);
-	if (unlikely(PageCgroupUsed(pc))) {
-		unlock_page_cgroup(pc);
+	if (TestSetPageCgroupUsed(pc)) {
 		res_counter_uncharge(&mem->res, PAGE_SIZE);
-		css_put(&mem->css);
 		preempt_enable();
 		goto done;
 	}
-	pc->mem_cgroup = mem;
 	/*
-	 * If a page is accounted as a page cache, insert to inactive list.
-	 * If anon, insert to active list.
-	 */
-	pc->flags = pcg_default_flags[ctype];
-
-	mz = page_cgroup_zoneinfo(pc);
+ 	 *  page cgroup is *unused* now....but....
+ 	 *  We can assume old mem_cgroup's metadata is still available
+ 	 *  because pc is not on stale LRU after force_empty() is called.
+ 	 */
+	if (likely(!PageCgroupLRU(pc)))
+		pc->flags = pcg_default_flags[ctype];
+	else {
+		mz = page_cgroup_zoneinfo(pc);
+		spin_lock_irqsave(&mz->lru_lock, flags);
+		if (PageCgroupLRU(pc)) {
+			__mem_cgroup_remove_list(mz, pc);
+			ClearPageCgroupLRU(pc);
+		}
+		pc->flags = pcg_default_flags[ctype];
+		spin_unlock_irqrestore(&mz->lru_lock, flags);
+	}
 
-	spin_lock_irqsave(&mz->lru_lock, flags);
-	__mem_cgroup_add_list(mz, pc);
-	spin_unlock_irqrestore(&mz->lru_lock, flags);
-	unlock_page_cgroup(pc);
+	pc->mem_cgroup = mem;
+	set_page_cgroup_lru(pc);
 	preempt_enable();
 
 done:
 	return 0;
 out:
-	css_put(&mem->css);
 	return -ENOMEM;
 }
 
@@ -830,12 +881,12 @@ __mem_cgroup_uncharge_common(struct page
 		return;
 	}
 	ClearPageCgroupUsed(pc);
+	mem = pc->mem_cgroup;
 	unlock_page_cgroup(pc);
 	preempt_enable();
+	res_counter_uncharge(&mem->res, PAGE_SIZE);
 
-	mem = pc->mem_cgroup;
 	release_page_cgroup(pc);
-	res_counter_uncharge(&mem->res, PAGE_SIZE);
 
 	return;
 }

[PATCH 12/12] memcg: fix race at charging swap-in

[KAMEZAWA Hiroyuki]

There is a small race in do_swap_page(). When the page swapped-in is charged,
the mapcount can be greater than 0. But, at the same time some process (shares
it ) call unmap and make mapcount 1->0 and the page is uncharged.

For fixing this, I added a new interface.
  - precharge
   account to res_counter by PAGE_SIZE and try to free pages if necessary.
  - commit	
   register page_cgroup and add to LRU if necessary.
  - cancel
   uncharge PAGE_SIZE because of do_swap_page failure.

This protocol uses PCG_USED bit on page_cgroup for avoiding over accounting.
Usual mem_cgroup_charge_common() does precharge -> commit at a time.

These precharge/commit/cancel is useful and can be used for other places,
 - shmem, (and other places need precharge.)
 - migration
 - move_account(force_empty) etc...
etc..we'll revisit later.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 include/linux/memcontrol.h |   21 +++++++
 mm/memcontrol.c            |  135 +++++++++++++++++++++++++++++++--------------
 mm/memory.c                |    6 +-
 3 files changed, 120 insertions(+), 42 deletions(-)

Index: mmotm-2.6.27-rc7+/include/linux/memcontrol.h
===================================================================
--- mmotm-2.6.27-rc7+.orig/include/linux/memcontrol.h
+++ mmotm-2.6.27-rc7+/include/linux/memcontrol.h
@@ -31,6 +31,13 @@ struct mm_struct;
 
 extern int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
 				gfp_t gfp_mask);
+/* for swap handling */
+extern int mem_cgroup_precharge(struct mm_struct *mm,
+		gfp_t gfp_mask, struct mem_cgroup **ptr);
+extern void mem_cgroup_commit_charge_swap(struct page *page,
+					struct mem_cgroup *ptr);
+extern void mem_cgroup_cancel_charge_swap(struct mem_cgroup *ptr);
+
 extern int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
 					gfp_t gfp_mask);
 extern void mem_cgroup_move_lists(struct page *page, enum lru_list lru);
@@ -85,6 +92,20 @@ static inline int mem_cgroup_cache_charg
 	return 0;
 }
 
+static int mem_cgroup_precharge(struct mm_struct *mm,
+				gfp_t gfp_mask, struct mem_cgroup **ptr)
+{
+	return 0;
+}
+
+static void mem_cgroup_commit_charge_swap(struct page *page,
+					  struct mem_cgroup *ptr)
+{
+}
+static void mem_cgroup_cancel_charge_swap(struct mem_cgroup *ptr)
+{
+}
+
 static inline void mem_cgroup_uncharge_page(struct page *page)
 {
 }
Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -698,52 +698,44 @@ static void drain_page_cgroup_all(void)
 
 
 /*
- * Charge the memory controller for page usage.
- * Return
- * 0 if the charge was successful
- * < 0 if the cgroup is over its limit
+ * charge against mem_cgroup linked to this mm. (or *ptr)
+ *
+ * This just charge PAGE_SIZE and reduce memory usage if necessary.
+ *
+ * Pages on radix-tree is charged at radix-tree add/remove under lock.
+ * new pages are charged at allocation and both are guaranteed to be that
+ * there are no racy users. We does precharge->commit at once.
+ *
+ * About swapcache, we can't trust page->mapcount until it's mapped.
+ * Then we do precharge before map and commit/cancel after the mapping is
+ * established. (see below, we have commit_swap and cancel_swap)
  */
-static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
-				gfp_t gfp_mask, enum charge_type ctype,
-				struct mem_cgroup *memcg)
+
+int mem_cgroup_precharge(struct mm_struct *mm,
+			 gfp_t mask, struct mem_cgroup **ptr)
 {
 	struct mem_cgroup *mem;
-	struct page_cgroup *pc;
-	unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
-	struct mem_cgroup_per_zone *mz;
-	unsigned long flags;
-
-	pc = lookup_page_cgroup(page);
-	/* can happen at boot */
-	if (unlikely(!pc))
-		return 0;
-	prefetchw(pc);
-	/*
-	 * We always charge the cgroup the mm_struct belongs to.
-	 * The mm_struct's mem_cgroup changes on task migration if the
-	 * thread group leader migrates. It's possible that mm is not
-	 * set, if so charge the init_mm (happens for pagecache usage).
-	 */
+	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
 
-	if (likely(!memcg)) {
-		rcu_read_lock();
+	rcu_read_lock();
+	if (!*ptr) {
 		mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
 		if (unlikely(!mem)) {
 			rcu_read_unlock();
-			return 0;
+			return -ESRCH;
 		}
-		rcu_read_unlock();
+		*ptr = mem;
 	} else {
-		mem = memcg;
+		mem = *ptr;
 	}
+	rcu_read_unlock();
 
+	css_get(&mem->css);
 	while (unlikely(res_counter_charge(&mem->res, PAGE_SIZE))) {
-		if (!(gfp_mask & __GFP_WAIT))
-			goto out;
-
-		if (try_to_free_mem_cgroup_pages(mem, gfp_mask))
+		if (!(mask & __GFP_WAIT))
+			goto nomem;
+		if (try_to_free_mem_cgroup_pages(mem, mask))
 			continue;
-
 		/*
 		 * try_to_free_mem_cgroup_pages() might not give us a full
 		 * picture of reclaim. Some pages are reclaimed and might be
@@ -755,16 +747,31 @@ static int mem_cgroup_charge_common(stru
 			continue;
 
 		if (!nr_retries--) {
-			mem_cgroup_out_of_memory(mem, gfp_mask);
-			goto out;
+			mem_cgroup_out_of_memory(mem, mask);
+			goto nomem;
 		}
 	}
+	return 0;
+nomem:
+	css_put(&mem->css);
+	return -ENOMEM;
+}
 
+void mem_cgroup_commit_charge(struct page_cgroup *pc,
+			      struct mem_cgroup *mem,
+			      enum charge_type ctype)
+{
+	struct mem_cgroup_per_zone *mz;
+	unsigned long flags;
+
+	if (!mem)
+		return;
 	preempt_disable();
 	if (TestSetPageCgroupUsed(pc)) {
 		res_counter_uncharge(&mem->res, PAGE_SIZE);
+		css_put(&mem->css);
 		preempt_enable();
-		goto done;
+		return;
 	}
 	/*
  	 *  page cgroup is *unused* now....but....
@@ -786,14 +793,43 @@ static int mem_cgroup_charge_common(stru
 
 	pc->mem_cgroup = mem;
 	set_page_cgroup_lru(pc);
+	css_put(&mem->css);
 	preempt_enable();
+}
 
-done:
+/*
+ * Charge the memory controller for page usage.
+ * Return
+ * 0 if the charge was successful
+ * < 0 if the cgroup is over its limit
+ */
+static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
+				gfp_t gfp_mask, enum charge_type ctype,
+				struct mem_cgroup *memcg)
+{
+	struct page_cgroup *pc;
+	struct mem_cgroup *ptr = memcg;
+	int ret;
+
+	pc = lookup_page_cgroup(page);
+	/* can happen at boot */
+	if (unlikely(!pc))
+		return 0;
+	prefetchw(pc);
+
+	ret = mem_cgroup_precharge(mm, gfp_mask, &ptr);
+	if (likely(!ret)) {
+		mem_cgroup_commit_charge(pc, ptr, ctype);
+		return 0;
+	}
+	if (unlikely((ret == -ENOMEM)))
+		return ret;
+	/* ESRCH case */
 	return 0;
-out:
-	return -ENOMEM;
 }
 
+
+
 int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask)
 {
 	if (mem_cgroup_subsys.disabled)
@@ -806,7 +842,7 @@ int mem_cgroup_charge(struct page *page,
 	 * But page->mapping may have out-of-use anon_vma pointer,
 	 * detecit it by PageAnon() check. newly-mapped-anon's page->mapping
 	 * is NULL.
-  	 */
+	 */
 	if (page_mapped(page) || (page->mapping && !PageAnon(page)))
 		return 0;
 	if (unlikely(!mm))
@@ -857,6 +893,25 @@ int mem_cgroup_cache_charge(struct page 
 				MEM_CGROUP_CHARGE_TYPE_SHMEM, NULL);
 }
 
+
+void mem_cgroup_commit_charge_swap(struct page *page, struct mem_cgroup *ptr)
+{
+	struct page_cgroup *pc;
+	if (!ptr)
+		return;
+	pc = lookup_page_cgroup(page);
+	mem_cgroup_commit_charge(pc, ptr, MEM_CGROUP_CHARGE_TYPE_MAPPED);
+}
+
+void mem_cgroup_cancel_charge_swap(struct mem_cgroup *mem)
+{
+	if (!mem)
+		return;
+	res_counter_uncharge(&mem->res, PAGE_SIZE);
+	css_put(&mem->css);
+}
+
+
 /*
  * uncharge if !page_mapped(page)
  */
Index: mmotm-2.6.27-rc7+/mm/memory.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memory.c
+++ mmotm-2.6.27-rc7+/mm/memory.c
@@ -2287,6 +2287,7 @@ static int do_swap_page(struct mm_struct
 	struct page *page;
 	swp_entry_t entry;
 	pte_t pte;
+	struct mem_cgroup *ptr = NULL;
 	int ret = 0;
 
 	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
@@ -2323,7 +2324,7 @@ static int do_swap_page(struct mm_struct
 	lock_page(page);
 	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
 
-	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
+	if (mem_cgroup_precharge(mm, GFP_KERNEL, &ptr) == -ENOMEM) {
 		ret = VM_FAULT_OOM;
 		goto out;
 	}
@@ -2353,6 +2354,7 @@ static int do_swap_page(struct mm_struct
 	flush_icache_page(vma, page);
 	set_pte_at(mm, address, page_table, pte);
 	page_add_anon_rmap(page, vma, address);
+	mem_cgroup_commit_charge_swap(page, ptr);
 
 	swap_free(entry);
 	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
@@ -2373,7 +2375,7 @@ unlock:
 out:
 	return ret;
 out_nomap:
-	mem_cgroup_uncharge_page(page);
+	mem_cgroup_cancel_charge_swap(ptr);
 	pte_unmap_unlock(page_table, ptl);
 	unlock_page(page);
 	page_cache_release(page);

Re: [PATCH 0/12] memcg updates v5

[Daisuke Nishimura]

On Thu, 25 Sep 2008 15:11:24 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> Hi, I updated the stack and reflected comments.
> Against the latest mmotm. (rc7-mm1)
> 
> Major changes from previous one is 
>   - page_cgroup allocation/lookup manner is changed.
>     all FLATMEM/DISCONTIGMEM/SPARSEMEM and MEMORY_HOTPLUG is supported.
>   - force_empty is totally rewritten. and a problem that "force_empty takes long time"
>     in previous version is fixed (I think...)
>   - reordered patches.
>      - first half are easy ones.
>      - second half are big ones.
> 
> I'm still testing with full debug option. No problem found yet.
> (I'm afraid of race condition which have not been caught yet.)
> 
> [1/12]  avoid accounting special mappings not on LRU. (fix)
> [2/12]  move charege() call to swapped-in page under lock_page() (clean up)
> [3/12]  make root cgroup to be unlimited. (change semantics.)
> [4/12]  make page->mapping NULL before calling uncharge (clean up)
> [5/12]  make page->flags to use atomic ops. (changes in infrastructure)
> [6/12]  optimize stat. (clean up)
> [7/12]  add support function for moving account. (new function)
> [8/12]  rewrite force_empty to use move_account. (change semantics.)
> [9/12]  allocate all page_cgroup at boot. (changes in infrastructure)
> [10/12] free page_cgroup from LRU in lazy way (optimize)
> [11/12] add page_cgroup to LRU in lazy way (optimize)
> [12/12] fix race at charging swap  (fix by new logic.)
> 
> *Any* comment is welcome.
> 
> Thanks,
> -Kame
> 

I got general protection fault.

(log from dump)
general protection fault: 0000 [1] SMP
last sysfs file: /sys/devices/system/cpu/cpu15/cache/index1/shared_cpu_map
CPU 0
Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp ipv6
autofs4 hidp rfcomm l2cap bluetooth sunrpc microcode dm_mirror dm_log dm_multipath dm_mod
rfkill input_polldev sbs sbshc battery ac lp sg e1000 ide_cd_mod cdrom button acpi_memhotp
lug serio_raw rtc_cmos parport_pc rtc_core parport rtc_lib i2c_i801 i2c_core pcspkr shpchp
 ata_piix libata megaraid_mbox megaraid_mm sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci
_hcd
Pid: 8001, comm: shmem_test_02 Tainted: G        W 2.6.27-rc7-mm1-7eacf5c9 #1
RIP: 0010:[<ffffffff802a0ebb>]  [<ffffffff802a0ebb>] __mem_cgroup_move_lists+0x8b/0xa2
RSP: 0018:ffff8800bb4ad888  EFLAGS: 00010046
RAX: ffff88010b253080 RBX: ffff88010c67d618 RCX: dead000000100100
RDX: dead000000200200 RSI: ffff88010b253088 RDI: ffff88010c67d630
RBP: 0000000000000000 R08: ffff88010fc020a3 R09: 000000000000000f
R10: ffffffff802a204a R11: 00000000fffffffa R12: ffff88010b253080
R13: 0000000000000000 R14: ffff8800bb4ad9c8 R15: 0000000000000000
FS:  00007f4600faa6f0(0000) GS:ffffffff80638900(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00000033af86c027 CR3: 00000000c1549000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process shmem_test_02 (pid: 8001, threadinfo ffff8800bb4ac000, task ffff880107d21470)
Stack:  ffffe200028ef8b0 0000000000000082 ffff88010c67d618 ffffffff802a1cb9
 ffff880000016f80 0000000000000000 ffff880000016f80 ffffe200028ef888
 ffff8800bb4adb38 ffffffff8027dd09 ffffc20001859000 0000000000000000
Call Trace:
 [<ffffffff802a1cb9>] mem_cgroup_move_lists+0x50/0x74
 [<ffffffff8027dd09>] shrink_list+0x443/0x4ff
 [<ffffffff8027e04e>] shrink_zone+0x289/0x315
 [<ffffffff802805d2>] congestion_wait+0x74/0x80
 [<ffffffff8024c006>] autoremove_wake_function+0x0/0x2e
 [<ffffffff8027e52a>] do_try_to_free_pages+0x259/0x3e3
 [<ffffffff8027e734>] try_to_free_mem_cgroup_pages+0x80/0x85
 [<ffffffff802a204a>] mem_cgroup_isolate_pages+0x0/0x1d2
 [<ffffffff802a13a3>] mem_cgroup_shrink_usage+0x60/0xba
 [<ffffffff802978a2>] shmem_getpage+0x455/0x7a0
 [<ffffffff8022c4f9>] target_load+0x2a/0x58
 [<ffffffff8022cf59>] place_entity+0x85/0xb3
 [<ffffffff8022f6db>] enqueue_entity+0x16e/0x18f
 [<ffffffff8022f781>] enqueue_task_fair+0x24/0x3a
 [<ffffffff8022cc33>] enqueue_task+0x50/0x5b
 [<ffffffff8023278e>] try_to_wake_up+0x241/0x253
 [<ffffffff8024c00f>] autoremove_wake_function+0x9/0x2e
 [<ffffffff8022c743>] __wake_up_common+0x41/0x74
 [<ffffffff8022dae7>] __wake_up+0x38/0x4f
 [<ffffffff80297c89>] shmem_fault+0x3b/0x68
 [<ffffffff802819f9>] __do_fault+0x51/0x3fb
 [<ffffffff80283592>] handle_mm_fault+0x1d6/0x791
 [<ffffffff804a2115>] do_page_fault+0x39c/0x773
 [<ffffffff804a2154>] do_page_fault+0x3db/0x773
 [<ffffffff804a0039>] error_exit+0x0/0x51
Code: 0b 10 eb 04 f0 80 23 ef f0 80 23 bf 89 e8 48 8d 7b 18 48 ff 44 c6 58 48 c1 e0 04 48
8b 4b 18 48 8b 57 08 48 8d 04 06 48 8d 70 08 <48> 89 51 08 48 89 0a 48 8b 50 08 59 5b 5d e
9 75 f4 09 00 58 5b
RIP  [<ffffffff802a0ebb>] __mem_cgroup_move_lists+0x8b/0xa2
 RSP <ffff8800bb4ad888>
---[ end trace 4eaa2a86a8e2da22 ]---

I've not investigated deeply yet, but it seems that it is trying to
handle an entry which has been already removed from list.
(I can see some "dead" pointer in registers.)

I was running some ltp tests (4 "page01" tests(8MB for each)
and 1 "shmem_test02" test(16MB)) in a group with limit=32M.


Anyway, I'll dig it more later.


Thanks,
Daisuke Nishimura.

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Re: [PATCH 0/12] memcg updates v5

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 11:32:28 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> I got general protection fault.
> 
> (log from dump)
> general protection fault: 0000 [1] SMP
> last sysfs file: /sys/devices/system/cpu/cpu15/cache/index1/shared_cpu_map

> Pid: 8001, comm: shmem_test_02 Tainted: G        W 2.6.27-rc7-mm1-7eacf5c9 #1
> RIP: 0010:[<ffffffff802a0ebb>]  [<ffffffff802a0ebb>] __mem_cgroup_move_lists+0x8b/0xa2
> RSP: 0018:ffff8800bb4ad888  EFLAGS: 00010046
> RAX: ffff88010b253080 RBX: ffff88010c67d618 RCX: dead000000100100
> RDX: dead000000200200 RSI: ffff88010b253088 RDI: ffff88010c67d630
> RBP: 0000000000000000 R08: ffff88010fc020a3 R09: 000000000000000f
> R10: ffffffff802a204a R11: 00000000fffffffa R12: ffff88010b253080
> R13: 0000000000000000 R14: ffff8800bb4ad9c8 R15: 0000000000000000
> FS:  00007f4600faa6f0(0000) GS:ffffffff80638900(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> CR2: 00000033af86c027 CR3: 00000000c1549000 CR4: 00000000000006e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Process shmem_test_02 (pid: 8001, threadinfo ffff8800bb4ac000, task ffff880107d21470)
> Stack:  ffffe200028ef8b0 0000000000000082 ffff88010c67d618 ffffffff802a1cb9
>  ffff880000016f80 0000000000000000 ffff880000016f80 ffffe200028ef888
>  ffff8800bb4adb38 ffffffff8027dd09 ffffc20001859000 0000000000000000
> Call Trace:
>  [<ffffffff802a1cb9>] mem_cgroup_move_lists+0x50/0x74
>  [<ffffffff8027dd09>] shrink_list+0x443/0x4ff
>  [<ffffffff8027e04e>] shrink_zone+0x289/0x315
>  [<ffffffff802805d2>] congestion_wait+0x74/0x80
>  [<ffffffff8024c006>] autoremove_wake_function+0x0/0x2e
>  [<ffffffff8027e52a>] do_try_to_free_pages+0x259/0x3e3
>  [<ffffffff8027e734>] try_to_free_mem_cgroup_pages+0x80/0x85
>  [<ffffffff802a204a>] mem_cgroup_isolate_pages+0x0/0x1d2

> Code: 0b 10 eb 04 f0 80 23 ef f0 80 23 bf 89 e8 48 8d 7b 18 48 ff 44 c6 58 48 c1 e0 04 48
> 8b 4b 18 48 8b 57 08 48 8d 04 06 48 8d 70 08 <48> 89 51 08 48 89 0a 48 8b 50 08 59 5b 5d e
> 9 75 f4 09 00 58 5b
> RIP  [<ffffffff802a0ebb>] __mem_cgroup_move_lists+0x8b/0xa2
>  RSP <ffff8800bb4ad888>
> ---[ end trace 4eaa2a86a8e2da22 ]---
> 
> I've not investigated deeply yet, but it seems that it is trying to
> handle an entry which has been already removed from list.
> (I can see some "dead" pointer in registers.)
> 
> I was running some ltp tests (4 "page01" tests(8MB for each)
> and 1 "shmem_test02" test(16MB)) in a group with limit=32M.
> 
> 
> Anyway, I'll dig it more later.
> 
Thank you.

How about following ?
-Kame
==
Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -597,8 +597,8 @@ __set_page_cgroup_lru(struct memcg_percp
 			spin_lock(&mz->lru_lock);
 		}
 		if (PageCgroupUsed(pc) && !PageCgroupLRU(pc)) {
-			SetPageCgroupLRU(pc);
 			__mem_cgroup_add_list(mz, pc);
+			SetPageCgroupLRU(pc);
 		}
 	}
 






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Re: [PATCH 0/12] memcg updates v5

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 11:58:10 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> Thank you.
> 
> How about following ?
> -Kame
> ==
> Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
> ===================================================================
> --- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
> +++ mmotm-2.6.27-rc7+/mm/memcontrol.c
> @@ -597,8 +597,8 @@ __set_page_cgroup_lru(struct memcg_percp
>  			spin_lock(&mz->lru_lock);
>  		}
>  		if (PageCgroupUsed(pc) && !PageCgroupLRU(pc)) {
> -			SetPageCgroupLRU(pc);
>  			__mem_cgroup_add_list(mz, pc);
> +			SetPageCgroupLRU(pc);
>  		}
>  	}
>  
Of course, remove side should be..
-Kame
==
Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -564,8 +564,8 @@ __release_page_cgroup(struct memcg_percp
 			spin_lock(&mz->lru_lock);
 		}
 		if (!PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
-			__mem_cgroup_remove_list(mz, pc);
 			ClearPageCgroupLRU(pc);
+			__mem_cgroup_remove_list(mz, pc);
 		}
 	}
 	if (prev_mz)
@@ -597,8 +597,8 @@ __set_page_cgroup_lru(struct memcg_percp
 			spin_lock(&mz->lru_lock);
 		}
 		if (PageCgroupUsed(pc) && !PageCgroupLRU(pc)) {
-			SetPageCgroupLRU(pc);
 			__mem_cgroup_add_list(mz, pc);
+			SetPageCgroupLRU(pc);
 		}
 	}
 

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Re: [PATCH 0/12] memcg updates v5

[Daisuke Nishimura]

On Fri, 26 Sep 2008 12:04:08 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> On Fri, 26 Sep 2008 11:58:10 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> 
> > Thank you.
> > 
> > How about following ?
> > -Kame
> > ==
> > Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
> > ===================================================================
> > --- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
> > +++ mmotm-2.6.27-rc7+/mm/memcontrol.c
> > @@ -597,8 +597,8 @@ __set_page_cgroup_lru(struct memcg_percp
> >  			spin_lock(&mz->lru_lock);
> >  		}
> >  		if (PageCgroupUsed(pc) && !PageCgroupLRU(pc)) {
> > -			SetPageCgroupLRU(pc);
> >  			__mem_cgroup_add_list(mz, pc);
> > +			SetPageCgroupLRU(pc);
> >  		}
> >  	}
> >  
> Of course, remove side should be..
> -Kame
> ==
> Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
> ===================================================================
> --- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
> +++ mmotm-2.6.27-rc7+/mm/memcontrol.c
> @@ -564,8 +564,8 @@ __release_page_cgroup(struct memcg_percp
>  			spin_lock(&mz->lru_lock);
>  		}
>  		if (!PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
> -			__mem_cgroup_remove_list(mz, pc);
>  			ClearPageCgroupLRU(pc);
> +			__mem_cgroup_remove_list(mz, pc);
>  		}
>  	}
>  	if (prev_mz)
> @@ -597,8 +597,8 @@ __set_page_cgroup_lru(struct memcg_percp
>  			spin_lock(&mz->lru_lock);
>  		}
>  		if (PageCgroupUsed(pc) && !PageCgroupLRU(pc)) {
> -			SetPageCgroupLRU(pc);
>  			__mem_cgroup_add_list(mz, pc);
> +			SetPageCgroupLRU(pc);
>  		}
>  	}
>  
> 

I'll test it with updated version of 9-11 and report you back.


Thanks,
Daisuke Nishimura.

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Re: [PATCH 0/12] memcg updates v5

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 12:00:19 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> I'll test it with updated version of 9-11 and report you back.
> 
Thank you. below is the new one...(Sorry!)

-Kame
==
Check LRU bit under lru_lock.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 mm/memcontrol.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -340,11 +340,12 @@ void mem_cgroup_move_lists(struct page *
 	if (!trylock_page_cgroup(pc))
 		return;
 
-	if (PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
+	if (PageCgroupUsed(pc)) {
 		mem = pc->mem_cgroup;
 		mz = page_cgroup_zoneinfo(pc);
 		spin_lock_irqsave(&mz->lru_lock, flags);
-		__mem_cgroup_move_lists(pc, lru);
+		if (PageCgroupLRU(pc))
+			__mem_cgroup_move_lists(pc, lru);
 		spin_unlock_irqrestore(&mz->lru_lock, flags);
 	}
 	unlock_page_cgroup(pc);
@@ -564,8 +565,8 @@ __release_page_cgroup(struct memcg_percp
 			spin_lock(&mz->lru_lock);
 		}
 		if (!PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
-			__mem_cgroup_remove_list(mz, pc);
 			ClearPageCgroupLRU(pc);
+			__mem_cgroup_remove_list(mz, pc);
 		}
 	}
 	if (prev_mz)
@@ -597,8 +598,8 @@ __set_page_cgroup_lru(struct memcg_percp
 			spin_lock(&mz->lru_lock);
 		}
 		if (PageCgroupUsed(pc) && !PageCgroupLRU(pc)) {
-			SetPageCgroupLRU(pc);
 			__mem_cgroup_add_list(mz, pc);
+			SetPageCgroupLRU(pc);
 		}
 	}
 



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Re: [PATCH 0/12] memcg updates v5

[Daisuke Nishimura]

On Fri, 26 Sep 2008 13:05:34 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> On Fri, 26 Sep 2008 12:00:19 +0900
> Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> 
> > I'll test it with updated version of 9-11 and report you back.
> > 
> Thank you. below is the new one...(Sorry!)
> 
> -Kame
> ==
> Check LRU bit under lru_lock.
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
>  mm/memcontrol.c |    9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
> ===================================================================
> --- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
> +++ mmotm-2.6.27-rc7+/mm/memcontrol.c
> @@ -340,11 +340,12 @@ void mem_cgroup_move_lists(struct page *
>  	if (!trylock_page_cgroup(pc))
>  		return;
>  
> -	if (PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
> +	if (PageCgroupUsed(pc)) {
>  		mem = pc->mem_cgroup;
>  		mz = page_cgroup_zoneinfo(pc);
>  		spin_lock_irqsave(&mz->lru_lock, flags);
> -		__mem_cgroup_move_lists(pc, lru);
> +		if (PageCgroupLRU(pc))
> +			__mem_cgroup_move_lists(pc, lru);
>  		spin_unlock_irqrestore(&mz->lru_lock, flags);
>  	}
>  	unlock_page_cgroup(pc);
> @@ -564,8 +565,8 @@ __release_page_cgroup(struct memcg_percp
>  			spin_lock(&mz->lru_lock);
>  		}
>  		if (!PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
> -			__mem_cgroup_remove_list(mz, pc);
>  			ClearPageCgroupLRU(pc);
> +			__mem_cgroup_remove_list(mz, pc);
>  		}
>  	}
>  	if (prev_mz)
> @@ -597,8 +598,8 @@ __set_page_cgroup_lru(struct memcg_percp
>  			spin_lock(&mz->lru_lock);
>  		}
>  		if (PageCgroupUsed(pc) && !PageCgroupLRU(pc)) {
> -			SetPageCgroupLRU(pc);
>  			__mem_cgroup_add_list(mz, pc);
> +			SetPageCgroupLRU(pc);
>  		}
>  	}
>  
> 

Unfortunately, there remains some bugs yet...

------------[ cut here ]------------
WARNING: at lib/list_debug.c:51 list_del+0x5c/0x87()
list_del corruption. next->prev should be ffff88010ca291e8, but was dead000000200200
Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp ipv6
autofs4 hidp rfcomm l2cap bluetooth sunrpc microcode dm_mirror dm_log dm_multipath dm_mod
rfkill input_polldev sbs sbshc battery ac lp sg e1000 ide_cd_mod cdrom button acpi_memhotp
lug parport_pc rtc_cmos rtc_core parport serio_raw rtc_lib i2c_i801 i2c_core shpchp pcspkr
 ata_piix libata megaraid_mbox megaraid_mm sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci
_hcd
Pid: 3940, comm: bash Tainted: G        W 2.6.27-rc7-mm1-dd8bf0fe #1
Call Trace:
 [<ffffffff8023ac52>] warn_slowpath+0xb4/0xd2
 [<ffffffff8024c0ec>] prepare_to_wait_exclusive+0x38/0x5a
 [<ffffffff8024c089>] finish_wait+0x32/0x5d
 [<ffffffff8049ec80>] __wait_on_bit_lock+0x5b/0x66
 [<ffffffff80272ff4>] __lock_page+0x5e/0x64
 [<ffffffff8022c4f9>] target_load+0x2a/0x58
 [<ffffffff8022cf59>] place_entity+0x85/0xb3
 [<ffffffff8022f6db>] enqueue_entity+0x16e/0x18f
 [<ffffffff8027ff0a>] zone_statistics+0x3a/0x5d
 [<ffffffff8027ff0a>] zone_statistics+0x3a/0x5d
 [<ffffffff802788d3>] get_page_from_freelist+0x455/0x5bf
 [<ffffffff803402e8>] list_del+0x5c/0x87
 [<ffffffff802a1530>] mem_cgroup_commit_charge+0x6f/0xdd
 [<ffffffff802a16ed>] mem_cgroup_charge_common+0x4c/0x62
 [<ffffffff802835de>] handle_mm_fault+0x222/0x791
 [<ffffffff8027ff0a>] zone_statistics+0x3a/0x5d
 [<ffffffff8028235a>] follow_page+0x2d/0x2c2
 [<ffffffff80283e42>] __get_user_pages+0x2f5/0x3f3
 [<ffffffff802a74ed>] get_arg_page+0x46/0xa5
 [<ffffffff802a7724>] copy_strings+0xfc/0x1de
 [<ffffffff802a7827>] copy_strings_kernel+0x21/0x33
 [<ffffffff802a8aff>] do_execve+0x140/0x256
 [<ffffffff8020a495>] sys_execve+0x35/0x4c
 [<ffffffff8020c1ea>] stub_execve+0x6a/0xc0
---[ end trace 4eaa2a86a8e2da22 ]---
------------[ cut here ]------------
WARNING: at lib/list_debug.c:48 list_del+0x30/0x87()
list_del corruption. prev->next should be ffff88010ca29210, but was dead000000100100
Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp ipv6
autofs4 hidp rfcomm l2cap bluetooth sunrpc microcode dm_mirror dm_log dm_multipath dm_mod
rfkill input_polldev sbs sbshc battery ac lp sg e1000 ide_cd_mod cdrom button acpi_memhotp
lug parport_pc rtc_cmos rtc_core parport serio_raw rtc_lib i2c_i801 i2c_core shpchp pcspkr
 ata_piix libata megaraid_mbox megaraid_mm sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci
_hcd
Pid: 3940, comm: bash Tainted: G        W 2.6.27-rc7-mm1-dd8bf0fe #1
Call Trace:
 [<ffffffff8023ac52>] warn_slowpath+0xb4/0xd2
 [<ffffffff802bf928>] __getblk+0x25/0x21f
 [<ffffffffa0060f7e>] __ext3_journal_dirty_metadata+0x1e/0x46 [ext3]
 [<ffffffff8022dae7>] __wake_up+0x38/0x4f
 [<ffffffff802bc201>] __mark_inode_dirty+0x15c/0x16b
 [<ffffffff802b4ec7>] touch_atime+0x109/0x112
 [<ffffffff802b8284>] mnt_drop_write+0x25/0xdc
 [<ffffffff80274cf9>] generic_file_aio_read+0x4b8/0x515
 [<ffffffff803402bc>] list_del+0x30/0x87
 [<ffffffff802a1106>] __release_page_cgroup+0x68/0x8a
 [<ffffffff8028a67a>] page_remove_rmap+0x10e/0x12e
 [<ffffffff80282a65>] unmap_vmas+0x476/0x7f2
 [<ffffffff80286e5e>] exit_mmap+0xf0/0x176
 [<ffffffff8038ec62>] secure_ip_id+0x45/0x4a
 [<ffffffff802389e2>] mmput+0x30/0x88
 [<ffffffff802a868b>] flush_old_exec+0x487/0x77c
 [<ffffffff802a47b7>] vfs_read+0x11e/0x133
 [<ffffffff802d54c9>] load_elf_binary+0x338/0x16b6
 [<ffffffff802a74ed>] get_arg_page+0x46/0xa5
 [<ffffffff802a77f5>] copy_strings+0x1cd/0x1de
 [<ffffffff802a7907>] search_binary_handler+0xb0/0x22e
 [<ffffffff802a8b67>] do_execve+0x1a8/0x256
 [<ffffffff8020a495>] sys_execve+0x35/0x4c
 [<ffffffff8020c1ea>] stub_execve+0x6a/0xc0
---[ end trace 4eaa2a86a8e2da22 ]---
------------[ cut here ]------------
WARNING: at lib/list_debug.c:48 list_del+0x30/0x87()
list_del corruption. prev->next should be ffff88010c937d50, but was ffff88010ca052e8
Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp ipv6
autofs4 hidp rfcomm l2cap bluetooth sunrpc microcode dm_mirror dm_log dm_multipath dm_mod
rfkill input_polldev sbs sbshc battery ac lp sg e1000 ide_cd_mod cdrom button acpi_memhotp
lug parport_pc rtc_cmos rtc_core parport serio_raw rtc_lib i2c_i801 i2c_core shpchp pcspkr
 ata_piix libata megaraid_mbox megaraid_mm sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci
_hcd
Pid: 3943, comm: shmem_test_02 Tainted: G        W 2.6.27-rc7-mm1-dd8bf0fe #1
Call Trace:
 [<ffffffff8023ac52>] warn_slowpath+0xb4/0xd2
 [<ffffffff802974c2>] shmem_getpage+0x75/0x7a0
 [<ffffffff8027ff0a>] zone_statistics+0x3a/0x5d
 [<ffffffff802787d1>] get_page_from_freelist+0x353/0x5bf
 [<ffffffff8027ff0a>] zone_statistics+0x3a/0x5d
 [<ffffffff802787d1>] get_page_from_freelist+0x353/0x5bf
 [<ffffffff803402bc>] list_del+0x30/0x87
 [<ffffffff802a1530>] mem_cgroup_commit_charge+0x6f/0xdd
 [<ffffffff802a16ed>] mem_cgroup_charge_common+0x4c/0x62
 [<ffffffff8028214e>] do_wp_page+0x3ab/0x58a
 [<ffffffff80283af1>] handle_mm_fault+0x735/0x791
 [<ffffffff802cdf1e>] fcntl_setlk+0x233/0x263
 [<ffffffff804a20e5>] do_page_fault+0x39c/0x773
 [<ffffffff804a0009>] error_exit+0x0/0x51
---[ end trace 4eaa2a86a8e2da22 ]---
------------[ cut here ]------------
WARNING: at lib/list_debug.c:48 list_del+0x30/0x87()
list_del corruption. prev->next should be ffff88010ca052e8, but was ffff88010c4068a0
Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp ipv6
autofs4 hidp rfcomm l2cap bluetooth sunrpc microcode dm_mirror dm_log dm_multipath dm_mod
rfkill input_polldev sbs sbshc battery ac lp sg e1000 ide_cd_mod cdrom button acpi_memhotp
lug parport_pc rtc_cmos rtc_core parport serio_raw rtc_lib i2c_i801 i2c_core shpchp pcspkr
 ata_piix libata megaraid_mbox megaraid_mm sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci
_hcd
Pid: 3942, comm: shmem_test_02 Tainted: G        W 2.6.27-rc7-mm1-dd8bf0fe #1
Call Trace:
 [<ffffffff8023ac52>] warn_slowpath+0xb4/0xd2
 [<ffffffff80277283>] rmqueue_bulk+0x61/0x8b
 [<ffffffff8033b8a5>] number+0x106/0x1f9
 [<ffffffff8027ff0a>] zone_statistics+0x3a/0x5d
 [<ffffffff802787d1>] get_page_from_freelist+0x353/0x5bf
 [<ffffffff802775e7>] free_pages_bulk+0x198/0x20b
 [<ffffffff80277ffe>] __pagevec_free+0x21/0x2e
 [<ffffffff8027b410>] release_pages+0x151/0x19f
 [<ffffffff803402bc>] list_del+0x30/0x87
 [<ffffffff802a1106>] __release_page_cgroup+0x68/0x8a
 [<ffffffff802747c7>] __remove_from_page_cache+0x45/0x8f
 [<ffffffff80274d7d>] remove_from_page_cache+0x27/0x2f
 [<ffffffff8027c04b>] truncate_complete_page+0x49/0x59
 [<ffffffff8027c118>] truncate_inode_pages_range+0xbd/0x2ff
 [<ffffffff80298abb>] shmem_delete_inode+0x33/0xc4
 [<ffffffff80298a88>] shmem_delete_inode+0x0/0xc4
 [<ffffffff802b41af>] generic_delete_inode+0xb0/0x124
 [<ffffffff802b1655>] d_kill+0x21/0x43
 [<ffffffff802b28fe>] dput+0x111/0x11f
 [<ffffffff802a4ed8>] __fput+0x14f/0x17e
 [<ffffffff80286d39>] remove_vma+0x3d/0x72
 [<ffffffff80286ec5>] exit_mmap+0x157/0x176
 [<ffffffff802389e2>] mmput+0x30/0x88
 [<ffffffff8023c66a>] exit_mm+0xff/0x10a
 [<ffffffff8023dafc>] do_exit+0x210/0x7a5
 [<ffffffff80269c22>] audit_syscall_entry+0x12d/0x160
 [<ffffffff8023e0f7>] do_group_exit+0x66/0x96
 [<ffffffff8020bdcb>] system_call_fastpath+0x16/0x1b
---[ end trace 4eaa2a86a8e2da22 ]---
------------[ cut here ]------------
WARNING: at lib/list_debug.c:51 list_del+0x5c/0x87()
list_del corruption. next->prev should be ffff88010caf6b20, but was dead000000200200
Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp ipv6
autofs4 hidp rfcomm l2cap bluetooth sunrpc microcode dm_mirror dm_log dm_multipath dm_mod
rfkill input_polldev sbs sbshc battery ac lp sg e1000 ide_cd_mod cdrom button acpi_memhotp
lug parport_pc rtc_cmos rtc_core parport serio_raw rtc_lib i2c_i801 i2c_core shpchp pcspkr
 ata_piix libata megaraid_mbox megaraid_mm sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci
_hcd
Pid: 3932, comm: page01 Tainted: G        W 2.6.27-rc7-mm1-dd8bf0fe #1
Call Trace:
 [<ffffffff8023ac52>] warn_slowpath+0xb4/0xd2
 [<ffffffff802775e7>] free_pages_bulk+0x198/0x20b
 [<ffffffff8027b44c>] release_pages+0x18d/0x19f
 [<ffffffff803402e8>] list_del+0x5c/0x87
 [<ffffffff802a1106>] __release_page_cgroup+0x68/0x8a
 [<ffffffff8028a67a>] page_remove_rmap+0x10e/0x12e
 [<ffffffff80282a65>] unmap_vmas+0x476/0x7f2
 [<ffffffff80286e5e>] exit_mmap+0xf0/0x176
 [<ffffffff802389e2>] mmput+0x30/0x88
 [<ffffffff8023c66a>] exit_mm+0xff/0x10a
 [<ffffffff8023dafc>] do_exit+0x210/0x7a5
 [<ffffffff80269c22>] audit_syscall_entry+0x12d/0x160
 [<ffffffff8023e0f7>] do_group_exit+0x66/0x96
 [<ffffffff8020bdcb>] system_call_fastpath+0x16/0x1b
---[ end trace 4eaa2a86a8e2da22 ]---
------------[ cut here ]------------
WARNING: at lib/list_debug.c:48 list_del+0x30/0x87()
list_del corruption. prev->next should be ffff88010c4068a0, but was dead000000100100
Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp ipv6
autofs4 hidp rfcomm l2cap bluetooth sunrpc microcode dm_mirror dm_log dm_multipath dm_mod
rfkill input_polldev sbs sbshc battery ac lp sg e1000 ide_cd_mod cdrom button acpi_memhotp
lug parport_pc rtc_cmos rtc_core parport serio_raw rtc_lib i2c_i801 i2c_core shpchp pcspkr
 ata_piix libata megaraid_mbox megaraid_mm sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci
_hcd
Pid: 3934, comm: page01 Tainted: G        W 2.6.27-rc7-mm1-dd8bf0fe #1
Call Trace:
 [<ffffffff8023ac52>] warn_slowpath+0xb4/0xd2
 [<ffffffffa003b89c>] do_get_write_access+0x37d/0x3c3 [jbd]
 [<ffffffff802bf928>] __getblk+0x25/0x21f
 [<ffffffff8024bf27>] bit_waitqueue+0x10/0xa0
 [<ffffffffa003b89c>] do_get_write_access+0x37d/0x3c3 [jbd]
 [<ffffffff8024bf27>] bit_waitqueue+0x10/0xa0
 [<ffffffff80272e22>] find_get_page+0x18/0xc4
 [<ffffffff8024bf27>] bit_waitqueue+0x10/0xa0
 [<ffffffff803402bc>] list_del+0x30/0x87
 [<ffffffff802a1106>] __release_page_cgroup+0x68/0x8a
 [<ffffffff8028a67a>] page_remove_rmap+0x10e/0x12e
 [<ffffffff80282a65>] unmap_vmas+0x476/0x7f2
 [<ffffffff80286e5e>] exit_mmap+0xf0/0x176
 [<ffffffff802389e2>] mmput+0x30/0x88
 [<ffffffff8023c66a>] exit_mm+0xff/0x10a
 [<ffffffff8023dafc>] do_exit+0x210/0x7a5
 [<ffffffff80269c22>] audit_syscall_entry+0x12d/0x160
 [<ffffffff8023e0f7>] do_group_exit+0x66/0x96
 [<ffffffff8020bdcb>] system_call_fastpath+0x16/0x1b
---[ end trace 4eaa2a86a8e2da22 ]---

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Re: [PATCH 0/12] memcg updates v5

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 14:24:55 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> On Fri, 26 Sep 2008 13:05:34 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > On Fri, 26 Sep 2008 12:00:19 +0900
> > Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> > 
> > > I'll test it with updated version of 9-11 and report you back.
> > > 
> > Thank you. below is the new one...(Sorry!)
> > 
> > -Kame
> > ==
> > Check LRU bit under lru_lock.
> > 
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> > 
> >  mm/memcontrol.c |    9 +++++----
> >  1 file changed, 5 insertions(+), 4 deletions(-)
> > 
> > Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
> > ===================================================================
> > --- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
> > +++ mmotm-2.6.27-rc7+/mm/memcontrol.c
> > @@ -340,11 +340,12 @@ void mem_cgroup_move_lists(struct page *
> >  	if (!trylock_page_cgroup(pc))
> >  		return;
> >  
> > -	if (PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
> > +	if (PageCgroupUsed(pc)) {
> >  		mem = pc->mem_cgroup;
> >  		mz = page_cgroup_zoneinfo(pc);
> >  		spin_lock_irqsave(&mz->lru_lock, flags);
> > -		__mem_cgroup_move_lists(pc, lru);
> > +		if (PageCgroupLRU(pc))
> > +			__mem_cgroup_move_lists(pc, lru);
> >  		spin_unlock_irqrestore(&mz->lru_lock, flags);
> >  	}
> >  	unlock_page_cgroup(pc);
> > @@ -564,8 +565,8 @@ __release_page_cgroup(struct memcg_percp
> >  			spin_lock(&mz->lru_lock);
> >  		}
> >  		if (!PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
> > -			__mem_cgroup_remove_list(mz, pc);
> >  			ClearPageCgroupLRU(pc);
> > +			__mem_cgroup_remove_list(mz, pc);
> >  		}
> >  	}
> >  	if (prev_mz)
> > @@ -597,8 +598,8 @@ __set_page_cgroup_lru(struct memcg_percp
> >  			spin_lock(&mz->lru_lock);
> >  		}
> >  		if (PageCgroupUsed(pc) && !PageCgroupLRU(pc)) {
> > -			SetPageCgroupLRU(pc);
> >  			__mem_cgroup_add_list(mz, pc);
> > +			SetPageCgroupLRU(pc);
> >  		}
> >  	}
> >  
> > 
> 
> Unfortunately, there remains some bugs yet...
> 
I confirmed I can reproduce this.

I found one chance to cause this. (and confirmed this happens by printk)
                                   set_lru()..
                                      
   TestSetPageCgroup(pc);
   ....                            if (PageCgroupUsed(pc) && !PageCgroupLRU(pc))
   pc->mem_cgroup = mem;
                                      SetPageCgroupLRU();
                                      __mem_cgroup_add_list();


Then, page_cgroup will be added to wrong LRU whic doesn't match pc->mem_cgroup.

But there is still more...still digging.

Thanks,
-kame



> ------------[ cut here ]------------
> WARNING: at lib/list_debug.c:51 list_del+0x5c/0x87()
> list_del corruption. next->prev should be ffff88010ca291e8, but was dead000000200200
> Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp ipv6
> autofs4 hidp rfcomm l2cap bluetooth sunrpc microcode dm_mirror dm_log dm_multipath dm_mod
> rfkill input_polldev sbs sbshc battery ac lp sg e1000 ide_cd_mod cdrom button acpi_memhotp
> lug parport_pc rtc_cmos rtc_core parport serio_raw rtc_lib i2c_i801 i2c_core shpchp pcspkr
>  ata_piix libata megaraid_mbox megaraid_mm sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci
> _hcd
> Pid: 3940, comm: bash Tainted: G        W 2.6.27-rc7-mm1-dd8bf0fe #1
> Call Trace:
>  [<ffffffff8023ac52>] warn_slowpath+0xb4/0xd2
>  [<ffffffff8024c0ec>] prepare_to_wait_exclusive+0x38/0x5a
>  [<ffffffff8024c089>] finish_wait+0x32/0x5d
>  [<ffffffff8049ec80>] __wait_on_bit_lock+0x5b/0x66
>  [<ffffffff80272ff4>] __lock_page+0x5e/0x64
>  [<ffffffff8022c4f9>] target_load+0x2a/0x58
>  [<ffffffff8022cf59>] place_entity+0x85/0xb3
>  [<ffffffff8022f6db>] enqueue_entity+0x16e/0x18f
>  [<ffffffff8027ff0a>] zone_statistics+0x3a/0x5d
>  [<ffffffff8027ff0a>] zone_statistics+0x3a/0x5d
>  [<ffffffff802788d3>] get_page_from_freelist+0x455/0x5bf
>  [<ffffffff803402e8>] list_del+0x5c/0x87
>  [<ffffffff802a1530>] mem_cgroup_commit_charge+0x6f/0xdd
>  [<ffffffff802a16ed>] mem_cgroup_charge_common+0x4c/0x62
>  [<ffffffff802835de>] handle_mm_fault+0x222/0x791
>  [<ffffffff8027ff0a>] zone_statistics+0x3a/0x5d
>  [<ffffffff8028235a>] follow_page+0x2d/0x2c2
>  [<ffffffff80283e42>] __get_user_pages+0x2f5/0x3f3
>  [<ffffffff802a74ed>] get_arg_page+0x46/0xa5
>  [<ffffffff802a7724>] copy_strings+0xfc/0x1de
>  [<ffffffff802a7827>] copy_strings_kernel+0x21/0x33
>  [<ffffffff802a8aff>] do_execve+0x140/0x256
>  [<ffffffff8020a495>] sys_execve+0x35/0x4c
>  [<ffffffff8020c1ea>] stub_execve+0x6a/0xc0
> ---[ end trace 4eaa2a86a8e2da22 ]---
> ------------[ cut here ]------------
> WARNING: at lib/list_debug.c:48 list_del+0x30/0x87()
> list_del corruption. prev->next should be ffff88010ca29210, but was dead000000100100
> Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp ipv6
> autofs4 hidp rfcomm l2cap bluetooth sunrpc microcode dm_mirror dm_log dm_multipath dm_mod
> rfkill input_polldev sbs sbshc battery ac lp sg e1000 ide_cd_mod cdrom button acpi_memhotp
> lug parport_pc rtc_cmos rtc_core parport serio_raw rtc_lib i2c_i801 i2c_core shpchp pcspkr
>  ata_piix libata megaraid_mbox megaraid_mm sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci
> _hcd
> Pid: 3940, comm: bash Tainted: G        W 2.6.27-rc7-mm1-dd8bf0fe #1
> Call Trace:
>  [<ffffffff8023ac52>] warn_slowpath+0xb4/0xd2
>  [<ffffffff802bf928>] __getblk+0x25/0x21f
>  [<ffffffffa0060f7e>] __ext3_journal_dirty_metadata+0x1e/0x46 [ext3]
>  [<ffffffff8022dae7>] __wake_up+0x38/0x4f
>  [<ffffffff802bc201>] __mark_inode_dirty+0x15c/0x16b
>  [<ffffffff802b4ec7>] touch_atime+0x109/0x112
>  [<ffffffff802b8284>] mnt_drop_write+0x25/0xdc
>  [<ffffffff80274cf9>] generic_file_aio_read+0x4b8/0x515
>  [<ffffffff803402bc>] list_del+0x30/0x87
>  [<ffffffff802a1106>] __release_page_cgroup+0x68/0x8a
>  [<ffffffff8028a67a>] page_remove_rmap+0x10e/0x12e
>  [<ffffffff80282a65>] unmap_vmas+0x476/0x7f2
>  [<ffffffff80286e5e>] exit_mmap+0xf0/0x176
>  [<ffffffff8038ec62>] secure_ip_id+0x45/0x4a
>  [<ffffffff802389e2>] mmput+0x30/0x88
>  [<ffffffff802a868b>] flush_old_exec+0x487/0x77c
>  [<ffffffff802a47b7>] vfs_read+0x11e/0x133
>  [<ffffffff802d54c9>] load_elf_binary+0x338/0x16b6
>  [<ffffffff802a74ed>] get_arg_page+0x46/0xa5
>  [<ffffffff802a77f5>] copy_strings+0x1cd/0x1de
>  [<ffffffff802a7907>] search_binary_handler+0xb0/0x22e
>  [<ffffffff802a8b67>] do_execve+0x1a8/0x256
>  [<ffffffff8020a495>] sys_execve+0x35/0x4c
>  [<ffffffff8020c1ea>] stub_execve+0x6a/0xc0
> ---[ end trace 4eaa2a86a8e2da22 ]---
> ------------[ cut here ]------------
> WARNING: at lib/list_debug.c:48 list_del+0x30/0x87()
> list_del corruption. prev->next should be ffff88010c937d50, but was ffff88010ca052e8
> Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp ipv6
> autofs4 hidp rfcomm l2cap bluetooth sunrpc microcode dm_mirror dm_log dm_multipath dm_mod
> rfkill input_polldev sbs sbshc battery ac lp sg e1000 ide_cd_mod cdrom button acpi_memhotp
> lug parport_pc rtc_cmos rtc_core parport serio_raw rtc_lib i2c_i801 i2c_core shpchp pcspkr
>  ata_piix libata megaraid_mbox megaraid_mm sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci
> _hcd
> Pid: 3943, comm: shmem_test_02 Tainted: G        W 2.6.27-rc7-mm1-dd8bf0fe #1
> Call Trace:
>  [<ffffffff8023ac52>] warn_slowpath+0xb4/0xd2
>  [<ffffffff802974c2>] shmem_getpage+0x75/0x7a0
>  [<ffffffff8027ff0a>] zone_statistics+0x3a/0x5d
>  [<ffffffff802787d1>] get_page_from_freelist+0x353/0x5bf
>  [<ffffffff8027ff0a>] zone_statistics+0x3a/0x5d
>  [<ffffffff802787d1>] get_page_from_freelist+0x353/0x5bf
>  [<ffffffff803402bc>] list_del+0x30/0x87
>  [<ffffffff802a1530>] mem_cgroup_commit_charge+0x6f/0xdd
>  [<ffffffff802a16ed>] mem_cgroup_charge_common+0x4c/0x62
>  [<ffffffff8028214e>] do_wp_page+0x3ab/0x58a
>  [<ffffffff80283af1>] handle_mm_fault+0x735/0x791
>  [<ffffffff802cdf1e>] fcntl_setlk+0x233/0x263
>  [<ffffffff804a20e5>] do_page_fault+0x39c/0x773
>  [<ffffffff804a0009>] error_exit+0x0/0x51
> ---[ end trace 4eaa2a86a8e2da22 ]---
> ------------[ cut here ]------------
> WARNING: at lib/list_debug.c:48 list_del+0x30/0x87()
> list_del corruption. prev->next should be ffff88010ca052e8, but was ffff88010c4068a0
> Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp ipv6
> autofs4 hidp rfcomm l2cap bluetooth sunrpc microcode dm_mirror dm_log dm_multipath dm_mod
> rfkill input_polldev sbs sbshc battery ac lp sg e1000 ide_cd_mod cdrom button acpi_memhotp
> lug parport_pc rtc_cmos rtc_core parport serio_raw rtc_lib i2c_i801 i2c_core shpchp pcspkr
>  ata_piix libata megaraid_mbox megaraid_mm sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci
> _hcd
> Pid: 3942, comm: shmem_test_02 Tainted: G        W 2.6.27-rc7-mm1-dd8bf0fe #1
> Call Trace:
>  [<ffffffff8023ac52>] warn_slowpath+0xb4/0xd2
>  [<ffffffff80277283>] rmqueue_bulk+0x61/0x8b
>  [<ffffffff8033b8a5>] number+0x106/0x1f9
>  [<ffffffff8027ff0a>] zone_statistics+0x3a/0x5d
>  [<ffffffff802787d1>] get_page_from_freelist+0x353/0x5bf
>  [<ffffffff802775e7>] free_pages_bulk+0x198/0x20b
>  [<ffffffff80277ffe>] __pagevec_free+0x21/0x2e
>  [<ffffffff8027b410>] release_pages+0x151/0x19f
>  [<ffffffff803402bc>] list_del+0x30/0x87
>  [<ffffffff802a1106>] __release_page_cgroup+0x68/0x8a
>  [<ffffffff802747c7>] __remove_from_page_cache+0x45/0x8f
>  [<ffffffff80274d7d>] remove_from_page_cache+0x27/0x2f
>  [<ffffffff8027c04b>] truncate_complete_page+0x49/0x59
>  [<ffffffff8027c118>] truncate_inode_pages_range+0xbd/0x2ff
>  [<ffffffff80298abb>] shmem_delete_inode+0x33/0xc4
>  [<ffffffff80298a88>] shmem_delete_inode+0x0/0xc4
>  [<ffffffff802b41af>] generic_delete_inode+0xb0/0x124
>  [<ffffffff802b1655>] d_kill+0x21/0x43
>  [<ffffffff802b28fe>] dput+0x111/0x11f
>  [<ffffffff802a4ed8>] __fput+0x14f/0x17e
>  [<ffffffff80286d39>] remove_vma+0x3d/0x72
>  [<ffffffff80286ec5>] exit_mmap+0x157/0x176
>  [<ffffffff802389e2>] mmput+0x30/0x88
>  [<ffffffff8023c66a>] exit_mm+0xff/0x10a
>  [<ffffffff8023dafc>] do_exit+0x210/0x7a5
>  [<ffffffff80269c22>] audit_syscall_entry+0x12d/0x160
>  [<ffffffff8023e0f7>] do_group_exit+0x66/0x96
>  [<ffffffff8020bdcb>] system_call_fastpath+0x16/0x1b
> ---[ end trace 4eaa2a86a8e2da22 ]---
> ------------[ cut here ]------------
> WARNING: at lib/list_debug.c:51 list_del+0x5c/0x87()
> list_del corruption. next->prev should be ffff88010caf6b20, but was dead000000200200
> Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp ipv6
> autofs4 hidp rfcomm l2cap bluetooth sunrpc microcode dm_mirror dm_log dm_multipath dm_mod
> rfkill input_polldev sbs sbshc battery ac lp sg e1000 ide_cd_mod cdrom button acpi_memhotp
> lug parport_pc rtc_cmos rtc_core parport serio_raw rtc_lib i2c_i801 i2c_core shpchp pcspkr
>  ata_piix libata megaraid_mbox megaraid_mm sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci
> _hcd
> Pid: 3932, comm: page01 Tainted: G        W 2.6.27-rc7-mm1-dd8bf0fe #1
> Call Trace:
>  [<ffffffff8023ac52>] warn_slowpath+0xb4/0xd2
>  [<ffffffff802775e7>] free_pages_bulk+0x198/0x20b
>  [<ffffffff8027b44c>] release_pages+0x18d/0x19f
>  [<ffffffff803402e8>] list_del+0x5c/0x87
>  [<ffffffff802a1106>] __release_page_cgroup+0x68/0x8a
>  [<ffffffff8028a67a>] page_remove_rmap+0x10e/0x12e
>  [<ffffffff80282a65>] unmap_vmas+0x476/0x7f2
>  [<ffffffff80286e5e>] exit_mmap+0xf0/0x176
>  [<ffffffff802389e2>] mmput+0x30/0x88
>  [<ffffffff8023c66a>] exit_mm+0xff/0x10a
>  [<ffffffff8023dafc>] do_exit+0x210/0x7a5
>  [<ffffffff80269c22>] audit_syscall_entry+0x12d/0x160
>  [<ffffffff8023e0f7>] do_group_exit+0x66/0x96
>  [<ffffffff8020bdcb>] system_call_fastpath+0x16/0x1b
> ---[ end trace 4eaa2a86a8e2da22 ]---
> ------------[ cut here ]------------
> WARNING: at lib/list_debug.c:48 list_del+0x30/0x87()
> list_del corruption. prev->next should be ffff88010c4068a0, but was dead000000100100
> Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp ipv6
> autofs4 hidp rfcomm l2cap bluetooth sunrpc microcode dm_mirror dm_log dm_multipath dm_mod
> rfkill input_polldev sbs sbshc battery ac lp sg e1000 ide_cd_mod cdrom button acpi_memhotp
> lug parport_pc rtc_cmos rtc_core parport serio_raw rtc_lib i2c_i801 i2c_core shpchp pcspkr
>  ata_piix libata megaraid_mbox megaraid_mm sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci
> _hcd
> Pid: 3934, comm: page01 Tainted: G        W 2.6.27-rc7-mm1-dd8bf0fe #1
> Call Trace:
>  [<ffffffff8023ac52>] warn_slowpath+0xb4/0xd2
>  [<ffffffffa003b89c>] do_get_write_access+0x37d/0x3c3 [jbd]
>  [<ffffffff802bf928>] __getblk+0x25/0x21f
>  [<ffffffff8024bf27>] bit_waitqueue+0x10/0xa0
>  [<ffffffffa003b89c>] do_get_write_access+0x37d/0x3c3 [jbd]
>  [<ffffffff8024bf27>] bit_waitqueue+0x10/0xa0
>  [<ffffffff80272e22>] find_get_page+0x18/0xc4
>  [<ffffffff8024bf27>] bit_waitqueue+0x10/0xa0
>  [<ffffffff803402bc>] list_del+0x30/0x87
>  [<ffffffff802a1106>] __release_page_cgroup+0x68/0x8a
>  [<ffffffff8028a67a>] page_remove_rmap+0x10e/0x12e
>  [<ffffffff80282a65>] unmap_vmas+0x476/0x7f2
>  [<ffffffff80286e5e>] exit_mmap+0xf0/0x176
>  [<ffffffff802389e2>] mmput+0x30/0x88
>  [<ffffffff8023c66a>] exit_mm+0xff/0x10a
>  [<ffffffff8023dafc>] do_exit+0x210/0x7a5
>  [<ffffffff80269c22>] audit_syscall_entry+0x12d/0x160
>  [<ffffffff8023e0f7>] do_group_exit+0x66/0x96
>  [<ffffffff8020bdcb>] system_call_fastpath+0x16/0x1b
> ---[ end trace 4eaa2a86a8e2da22 ]---
> 

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Re: [PATCH 0/12] memcg updates v5

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 14:24:55 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> Unfortunately, there remains some bugs yet...
> 

Thank you for your patient good test!

I'm now testing following (and will do over-night test.)
In this an hour, this seems to work good. 
(under your test which usually panics in 10-20min on my box.)

==
page_cgroup is not valid until pc->mem_cgroup is set to appropriate value.
There is a small race between Set-Used-Bit and Set-Proper-pc->mem_cgroup.
This patch tries to fix that by adding PCG_VALID bit

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

 include/linux/page_cgroup.h |    3 +++
 mm/memcontrol.c             |   22 ++++++++++++++--------
 2 files changed, 17 insertions(+), 8 deletions(-)

Index: mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
===================================================================
--- mmotm-2.6.27-rc7+.orig/include/linux/page_cgroup.h
+++ mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
@@ -21,6 +21,7 @@ struct page_cgroup *lookup_page_cgroup(s
 
 enum {
 	/* flags for mem_cgroup */
+	PCG_VALID, /* you can access this page cgroup */
 	PCG_LOCK,  /* page cgroup is locked */
 	PCG_CACHE, /* charged as cache */
 	PCG_USED, /* this object is in use. */
@@ -50,6 +51,10 @@ static inline int TestSetPageCgroup##una
 /* Cache flag is set only once (at allocation) */
 TESTPCGFLAG(Cache, CACHE)
 
+TESTPCGFLAG(Valid, VALID)
+SETPCGFLAG(Valid, VALID)
+CLEARPCGFLAG(Valid, VALID)
+
 TESTPCGFLAG(Used, USED)
 CLEARPCGFLAG(Used, USED)
 TESTSETPCGFLAG(Used, USED)
Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -340,7 +340,7 @@ void mem_cgroup_move_lists(struct page *
 	if (!trylock_page_cgroup(pc))
 		return;
 
-	if (PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
+	if (PageCgroupValid(pc) && PageCgroupLRU(pc)) {
 		mem = pc->mem_cgroup;
 		mz = page_cgroup_zoneinfo(pc);
 		spin_lock_irqsave(&mz->lru_lock, flags);
@@ -434,7 +434,7 @@ unsigned long mem_cgroup_isolate_pages(u
 	list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
 		if (scan >= nr_to_scan)
 			break;
-		if (unlikely(!PageCgroupUsed(pc)))
+		if (unlikely(!PageCgroupValid(pc)))
 			continue;
 		page = pc->page;
 
@@ -511,7 +511,7 @@ int mem_cgroup_move_account(struct page 
 		return ret;
 	}
 
-	if (!PageCgroupUsed(pc)) {
+	if (!PageCgroupValid(pc)) {
 		res_counter_uncharge(&to->res, PAGE_SIZE);
 		goto out;
 	}
@@ -580,6 +580,7 @@ __set_page_cgroup_lru(struct memcg_percp
 	unsigned long flags;
 	struct mem_cgroup_per_zone *mz, *prev_mz;
 	struct page_cgroup *pc;
+	struct mem_cgroup *mem;
 	int i, nr;
 
 	local_irq_save(flags);
@@ -589,6 +590,7 @@ __set_page_cgroup_lru(struct memcg_percp
 
 	for (i = nr - 1; i >= 0; i--) {
 		pc = mpv->vec[i];
+		mem = pc->mem_cgroup;
 		mz = page_cgroup_zoneinfo(pc);
 		if (prev_mz != mz) {
 			if (prev_mz)
@@ -596,9 +598,11 @@ __set_page_cgroup_lru(struct memcg_percp
 			prev_mz = mz;
 			spin_lock(&mz->lru_lock);
 		}
-		if (PageCgroupUsed(pc) && !PageCgroupLRU(pc)) {
-			SetPageCgroupLRU(pc);
-			__mem_cgroup_add_list(mz, pc);
+		if (PageCgroupValid(pc) && !PageCgroupLRU(pc)) {
+			if (mem == pc->mem_cgroup) {
+				SetPageCgroupLRU(pc);
+				__mem_cgroup_add_list(mz, pc);
+			}
 		}
 	}
 
@@ -790,6 +794,7 @@ void mem_cgroup_commit_charge(struct pag
 	}
 
 	pc->mem_cgroup = mem;
+	SetPageCgroupValid(pc);
 	set_page_cgroup_lru(pc);
 	css_put(&mem->css);
 	preempt_enable();
@@ -928,6 +933,7 @@ __mem_cgroup_uncharge_common(struct page
 		return;
 	preempt_disable();
 	lock_page_cgroup(pc);
+	ClearPageCgroupValid(pc);
 	ClearPageCgroupUsed(pc);
 	mem = pc->mem_cgroup;
 	unlock_page_cgroup(pc);
@@ -970,7 +976,7 @@ int mem_cgroup_prepare_migration(struct 
 
 	pc = lookup_page_cgroup(page);
 	lock_page_cgroup(pc);
-	if (PageCgroupUsed(pc)) {
+	if (PageCgroupValid(pc)) {
 		mem = pc->mem_cgroup;
 		css_get(&mem->css);
 		if (PageCgroupCache(pc)) {
@@ -1086,7 +1092,7 @@ static void mem_cgroup_force_empty_list(
 	spin_lock_irqsave(&mz->lru_lock, flags);
 	list_for_each_entry_safe(pc, tmp, list, lru) {
 		page = pc->page;
-		if (!PageCgroupUsed(pc))
+		if (!PageCgroupValid(pc))
 			continue;
 		/* For avoiding race with speculative page cache handling. */
 		if (!PageLRU(page) || !get_page_unless_zero(page))

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Re: [PATCH 0/12] memcg updates v5

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 19:43:09 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> On Fri, 26 Sep 2008 14:24:55 +0900
> Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> > Unfortunately, there remains some bugs yet...
> > 
> 
> Thank you for your patient good test!
> 
> I'm now testing following (and will do over-night test.)
> In this an hour, this seems to work good. 
> (under your test which usually panics in 10-20min on my box.)
> 
This helps some, but causes other troubles. (But I know what it is.)
I'll add lock_page_cgroup() to charge side and see what happens.

Thanks,
-Kame



> ==
> page_cgroup is not valid until pc->mem_cgroup is set to appropriate value.
> There is a small race between Set-Used-Bit and Set-Proper-pc->mem_cgroup.
> This patch tries to fix that by adding PCG_VALID bit
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
>  include/linux/page_cgroup.h |    3 +++
>  mm/memcontrol.c             |   22 ++++++++++++++--------
>  2 files changed, 17 insertions(+), 8 deletions(-)
> 
> Index: mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
> ===================================================================
> --- mmotm-2.6.27-rc7+.orig/include/linux/page_cgroup.h
> +++ mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
> @@ -21,6 +21,7 @@ struct page_cgroup *lookup_page_cgroup(s
>  
>  enum {
>  	/* flags for mem_cgroup */
> +	PCG_VALID, /* you can access this page cgroup */
>  	PCG_LOCK,  /* page cgroup is locked */
>  	PCG_CACHE, /* charged as cache */
>  	PCG_USED, /* this object is in use. */
> @@ -50,6 +51,10 @@ static inline int TestSetPageCgroup##una
>  /* Cache flag is set only once (at allocation) */
>  TESTPCGFLAG(Cache, CACHE)
>  
> +TESTPCGFLAG(Valid, VALID)
> +SETPCGFLAG(Valid, VALID)
> +CLEARPCGFLAG(Valid, VALID)
> +
>  TESTPCGFLAG(Used, USED)
>  CLEARPCGFLAG(Used, USED)
>  TESTSETPCGFLAG(Used, USED)
> Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
> ===================================================================
> --- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
> +++ mmotm-2.6.27-rc7+/mm/memcontrol.c
> @@ -340,7 +340,7 @@ void mem_cgroup_move_lists(struct page *
>  	if (!trylock_page_cgroup(pc))
>  		return;
>  
> -	if (PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
> +	if (PageCgroupValid(pc) && PageCgroupLRU(pc)) {
>  		mem = pc->mem_cgroup;
>  		mz = page_cgroup_zoneinfo(pc);
>  		spin_lock_irqsave(&mz->lru_lock, flags);
> @@ -434,7 +434,7 @@ unsigned long mem_cgroup_isolate_pages(u
>  	list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
>  		if (scan >= nr_to_scan)
>  			break;
> -		if (unlikely(!PageCgroupUsed(pc)))
> +		if (unlikely(!PageCgroupValid(pc)))
>  			continue;
>  		page = pc->page;
>  
> @@ -511,7 +511,7 @@ int mem_cgroup_move_account(struct page 
>  		return ret;
>  	}
>  
> -	if (!PageCgroupUsed(pc)) {
> +	if (!PageCgroupValid(pc)) {
>  		res_counter_uncharge(&to->res, PAGE_SIZE);
>  		goto out;
>  	}
> @@ -580,6 +580,7 @@ __set_page_cgroup_lru(struct memcg_percp
>  	unsigned long flags;
>  	struct mem_cgroup_per_zone *mz, *prev_mz;
>  	struct page_cgroup *pc;
> +	struct mem_cgroup *mem;
>  	int i, nr;
>  
>  	local_irq_save(flags);
> @@ -589,6 +590,7 @@ __set_page_cgroup_lru(struct memcg_percp
>  
>  	for (i = nr - 1; i >= 0; i--) {
>  		pc = mpv->vec[i];
> +		mem = pc->mem_cgroup;
>  		mz = page_cgroup_zoneinfo(pc);
>  		if (prev_mz != mz) {
>  			if (prev_mz)
> @@ -596,9 +598,11 @@ __set_page_cgroup_lru(struct memcg_percp
>  			prev_mz = mz;
>  			spin_lock(&mz->lru_lock);
>  		}
> -		if (PageCgroupUsed(pc) && !PageCgroupLRU(pc)) {
> -			SetPageCgroupLRU(pc);
> -			__mem_cgroup_add_list(mz, pc);
> +		if (PageCgroupValid(pc) && !PageCgroupLRU(pc)) {
> +			if (mem == pc->mem_cgroup) {
> +				SetPageCgroupLRU(pc);
> +				__mem_cgroup_add_list(mz, pc);
> +			}
>  		}
>  	}
>  
> @@ -790,6 +794,7 @@ void mem_cgroup_commit_charge(struct pag
>  	}
>  
>  	pc->mem_cgroup = mem;
> +	SetPageCgroupValid(pc);
>  	set_page_cgroup_lru(pc);
>  	css_put(&mem->css);
>  	preempt_enable();
> @@ -928,6 +933,7 @@ __mem_cgroup_uncharge_common(struct page
>  		return;
>  	preempt_disable();
>  	lock_page_cgroup(pc);
> +	ClearPageCgroupValid(pc);
>  	ClearPageCgroupUsed(pc);
>  	mem = pc->mem_cgroup;
>  	unlock_page_cgroup(pc);
> @@ -970,7 +976,7 @@ int mem_cgroup_prepare_migration(struct 
>  
>  	pc = lookup_page_cgroup(page);
>  	lock_page_cgroup(pc);
> -	if (PageCgroupUsed(pc)) {
> +	if (PageCgroupValid(pc)) {
>  		mem = pc->mem_cgroup;
>  		css_get(&mem->css);
>  		if (PageCgroupCache(pc)) {
> @@ -1086,7 +1092,7 @@ static void mem_cgroup_force_empty_list(
>  	spin_lock_irqsave(&mz->lru_lock, flags);
>  	list_for_each_entry_safe(pc, tmp, list, lru) {
>  		page = pc->page;
> -		if (!PageCgroupUsed(pc))
> +		if (!PageCgroupValid(pc))
>  			continue;
>  		/* For avoiding race with speculative page cache handling. */
>  		if (!PageLRU(page) || !get_page_unless_zero(page))
> 
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Re: [PATCH 0/12] memcg updates v5

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> Hi, I updated the stack and reflected comments.
> Against the latest mmotm. (rc7-mm1)
> 
> Major changes from previous one is 
>   - page_cgroup allocation/lookup manner is changed.
>     all FLATMEM/DISCONTIGMEM/SPARSEMEM and MEMORY_HOTPLUG is supported.
>   - force_empty is totally rewritten. and a problem that "force_empty takes long time"
>     in previous version is fixed (I think...)
>   - reordered patches.
>      - first half are easy ones.
>      - second half are big ones.
> 
> I'm still testing with full debug option. No problem found yet.
> (I'm afraid of race condition which have not been caught yet.)
> 
> [1/12]  avoid accounting special mappings not on LRU. (fix)
> [2/12]  move charege() call to swapped-in page under lock_page() (clean up)
> [3/12]  make root cgroup to be unlimited. (change semantics.)
> [4/12]  make page->mapping NULL before calling uncharge (clean up)
> [5/12]  make page->flags to use atomic ops. (changes in infrastructure)
> [6/12]  optimize stat. (clean up)
> [7/12]  add support function for moving account. (new function)
> [8/12]  rewrite force_empty to use move_account. (change semantics.)
> [9/12]  allocate all page_cgroup at boot. (changes in infrastructure)
> [10/12] free page_cgroup from LRU in lazy way (optimize)
> [11/12] add page_cgroup to LRU in lazy way (optimize)
> [12/12] fix race at charging swap  (fix by new logic.)
> 
> *Any* comment is welcome.

Kame,

I'm beginning to review test the patches now. It would be really nice to split
the development patches from the maintenance ones. I think the full patchset has
too many things and is confusing to look at.


-- 
	Balbir

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Re: [PATCH 0/12] memcg updates v5

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 13:48:58 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> KAMEZAWA Hiroyuki wrote:
> > Hi, I updated the stack and reflected comments.
> > Against the latest mmotm. (rc7-mm1)
> > 
> > Major changes from previous one is 
> >   - page_cgroup allocation/lookup manner is changed.
> >     all FLATMEM/DISCONTIGMEM/SPARSEMEM and MEMORY_HOTPLUG is supported.
> >   - force_empty is totally rewritten. and a problem that "force_empty takes long time"
> >     in previous version is fixed (I think...)
> >   - reordered patches.
> >      - first half are easy ones.
> >      - second half are big ones.
> > 
> > I'm still testing with full debug option. No problem found yet.
> > (I'm afraid of race condition which have not been caught yet.)
> > 
> > [1/12]  avoid accounting special mappings not on LRU. (fix)
> > [2/12]  move charege() call to swapped-in page under lock_page() (clean up)
> > [3/12]  make root cgroup to be unlimited. (change semantics.)
> > [4/12]  make page->mapping NULL before calling uncharge (clean up)
> > [5/12]  make page->flags to use atomic ops. (changes in infrastructure)
> > [6/12]  optimize stat. (clean up)
> > [7/12]  add support function for moving account. (new function)
> > [8/12]  rewrite force_empty to use move_account. (change semantics.)
> > [9/12]  allocate all page_cgroup at boot. (changes in infrastructure)
> > [10/12] free page_cgroup from LRU in lazy way (optimize)
> > [11/12] add page_cgroup to LRU in lazy way (optimize)
> > [12/12] fix race at charging swap  (fix by new logic.)
> > 
> > *Any* comment is welcome.
> 
> Kame,
> 
> I'm beginning to review test the patches now. It would be really nice to split
> the development patches from the maintenance ones. I think the full patchset has
> too many things and is confusing to look at.
> 
I hope I can do....but maybe difficult.
If you give me ack, 1,2,4,6, can be pushed at early stage.

Thanks,
-Kame




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Re: [PATCH 0/12] memcg updates v5

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> On Fri, 26 Sep 2008 13:48:58 +0530
> Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> 
>> KAMEZAWA Hiroyuki wrote:
>>> Hi, I updated the stack and reflected comments.
>>> Against the latest mmotm. (rc7-mm1)
>>>
>>> Major changes from previous one is 
>>>   - page_cgroup allocation/lookup manner is changed.
>>>     all FLATMEM/DISCONTIGMEM/SPARSEMEM and MEMORY_HOTPLUG is supported.
>>>   - force_empty is totally rewritten. and a problem that "force_empty takes long time"
>>>     in previous version is fixed (I think...)
>>>   - reordered patches.
>>>      - first half are easy ones.
>>>      - second half are big ones.
>>>
>>> I'm still testing with full debug option. No problem found yet.
>>> (I'm afraid of race condition which have not been caught yet.)
>>>
>>> [1/12]  avoid accounting special mappings not on LRU. (fix)
>>> [2/12]  move charege() call to swapped-in page under lock_page() (clean up)
>>> [3/12]  make root cgroup to be unlimited. (change semantics.)
>>> [4/12]  make page->mapping NULL before calling uncharge (clean up)
>>> [5/12]  make page->flags to use atomic ops. (changes in infrastructure)
>>> [6/12]  optimize stat. (clean up)
>>> [7/12]  add support function for moving account. (new function)
>>> [8/12]  rewrite force_empty to use move_account. (change semantics.)
>>> [9/12]  allocate all page_cgroup at boot. (changes in infrastructure)
>>> [10/12] free page_cgroup from LRU in lazy way (optimize)
>>> [11/12] add page_cgroup to LRU in lazy way (optimize)
>>> [12/12] fix race at charging swap  (fix by new logic.)
>>>
>>> *Any* comment is welcome.
>> Kame,
>>
>> I'm beginning to review test the patches now. It would be really nice to split
>> the development patches from the maintenance ones. I think the full patchset has
>> too many things and is confusing to look at.
>>
> I hope I can do....but maybe difficult.
> If you give me ack, 1,2,4,6, can be pushed at early stage.

I think (1) might be OK, except for the accounting issues pointed out (change in
behaviour visible to end user again, sigh! :( ). Is (1) a serious issue? (2)
seems OK, except for the locking change for mark_page_accessed. I am looking at
(4) and (6) currently.

-- 
	Balbir

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Re: [PATCH 0/12] memcg updates v5

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 15:01:46 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> KAMEZAWA Hiroyuki wrote:
> > On Fri, 26 Sep 2008 13:48:58 +0530
> > Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> > 
> >> KAMEZAWA Hiroyuki wrote:
> >>> Hi, I updated the stack and reflected comments.
> >>> Against the latest mmotm. (rc7-mm1)
> >>>
> >>> Major changes from previous one is 
> >>>   - page_cgroup allocation/lookup manner is changed.
> >>>     all FLATMEM/DISCONTIGMEM/SPARSEMEM and MEMORY_HOTPLUG is supported.
> >>>   - force_empty is totally rewritten. and a problem that "force_empty takes long time"
> >>>     in previous version is fixed (I think...)
> >>>   - reordered patches.
> >>>      - first half are easy ones.
> >>>      - second half are big ones.
> >>>
> >>> I'm still testing with full debug option. No problem found yet.
> >>> (I'm afraid of race condition which have not been caught yet.)
> >>>
> >>> [1/12]  avoid accounting special mappings not on LRU. (fix)
> >>> [2/12]  move charege() call to swapped-in page under lock_page() (clean up)
> >>> [3/12]  make root cgroup to be unlimited. (change semantics.)
> >>> [4/12]  make page->mapping NULL before calling uncharge (clean up)
> >>> [5/12]  make page->flags to use atomic ops. (changes in infrastructure)
> >>> [6/12]  optimize stat. (clean up)
> >>> [7/12]  add support function for moving account. (new function)
> >>> [8/12]  rewrite force_empty to use move_account. (change semantics.)
> >>> [9/12]  allocate all page_cgroup at boot. (changes in infrastructure)
> >>> [10/12] free page_cgroup from LRU in lazy way (optimize)
> >>> [11/12] add page_cgroup to LRU in lazy way (optimize)
> >>> [12/12] fix race at charging swap  (fix by new logic.)
> >>>
> >>> *Any* comment is welcome.
> >> Kame,
> >>
> >> I'm beginning to review test the patches now. It would be really nice to split
> >> the development patches from the maintenance ones. I think the full patchset has
> >> too many things and is confusing to look at.
> >>
> > I hope I can do....but maybe difficult.
> > If you give me ack, 1,2,4,6, can be pushed at early stage.
> 
> I think (1) might be OK, except for the accounting issues pointed out (change in
> behaviour visible to end user again, sigh! :( ).
But it was just a BUG from my point of view...

> Is (1) a serious issue? 
considering force_empty(), it's serious.

> (2) seems OK, except for the locking change for mark_page_accessed. I am looking at
> (4) and (6) currently.
> 
Thanks,
-Kmae

> -- 
> 	Balbir
> 

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Re: [PATCH 0/12] memcg updates v5

[KAMEZAWA Hiroyuki]

On Fri, 26 Sep 2008 19:36:02 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> > I think (1) might be OK, except for the accounting issues pointed out (change in
> > behaviour visible to end user again, sigh! :( ).
> But it was just a BUG from my point of view...
> 
> > Is (1) a serious issue? 
> considering force_empty(), it's serious.
> 
> > (2) seems OK, except for the locking change for mark_page_accessed. I am looking at
> > (4) and (6) currently.
> > 

I'll do in following way in the next Monday.
Divide patches into 2 set

in early fix/optimize set.
  - push (2)
  - push (4)
  - push (6)
  - push (1)

drops (3).

I don't want to remove all? pages-never-on-LRU before fixing force_empty.

in updates
  - introduce atomic flags. (5)
  - add move_account() function (7)
  - add memory.attribute to each memcg dir. (NEW)
  - enhance force_empty (was (8))
       - remove "forget all" logic. and add attribute to select following 2 behavior
          - call try_to_free_page() until the usage goes down to 0.
            This allows faiulre (if page is mlocked, we can't do.). (NEW)
          - call move_account() to move all charges to its parent (as much as possible) (NEW)
          In future, I'd liket to add trash-box cgroup for force_empty somewhere.
  - allocate all page cgroup at boot (9)
  - lazy lru free/add (10,11) with fixes.
  - fix race at charging swap. (12)

After (9), all page and page_cgroup has one-to-one releationship and we want to
assume that "if page is alive and on LRU, it's accounted and has page_cgroup."
(other team, bio cgroup want to use page_cgroup and I want to make it easy.)

For this, fix to behavior of force_empty..."forget all" is necessary.
SwapCache handling is also necessary but I'd like to postpone until next set
because it's complicated.

After above all.
 - handle swap cache 
 - Mem+Swap controller.
 - add trashbox feature ?
 - add memory.shrink_usage_to file.

It's long way to what I really want to do....


Thanks,
-Kame








  - 




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Re: [PATCH 0/12] memcg updates v5

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> On Fri, 26 Sep 2008 19:36:02 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> 
>>> I think (1) might be OK, except for the accounting issues pointed out (change in
>>> behaviour visible to end user again, sigh! :( ).
>> But it was just a BUG from my point of view...
>>
>>> Is (1) a serious issue? 
>> considering force_empty(), it's serious.
>>
>>> (2) seems OK, except for the locking change for mark_page_accessed. I am looking at
>>> (4) and (6) currently.
>>>
> 
> I'll do in following way in the next Monday.
> Divide patches into 2 set
> 
> in early fix/optimize set.
>   - push (2)
>   - push (4)
>   - push (6)
>   - push (1)
> 

Yes, sounds reasonable

> drops (3).
> 
> I don't want to remove all? pages-never-on-LRU before fixing force_empty.
> 
> in updates
>   - introduce atomic flags. (5)
>   - add move_account() function (7)

without (3), don't we have a problem pushing (7)?

>   - add memory.attribute to each memcg dir. (NEW)
>   - enhance force_empty (was (8))
>        - remove "forget all" logic. and add attribute to select following 2 behavior
>           - call try_to_free_page() until the usage goes down to 0.
>             This allows faiulre (if page is mlocked, we can't do.). (NEW)
>           - call move_account() to move all charges to its parent (as much as possible) (NEW)
>           In future, I'd liket to add trash-box cgroup for force_empty somewhere.
>   - allocate all page cgroup at boot (9)
>   - lazy lru free/add (10,11) with fixes.
>   - fix race at charging swap. (12)
> 

I think (9) is probably the most important. I'll review it today

> After (9), all page and page_cgroup has one-to-one releationship and we want to
> assume that "if page is alive and on LRU, it's accounted and has page_cgroup."
> (other team, bio cgroup want to use page_cgroup and I want to make it easy.)
> 
> For this, fix to behavior of force_empty..."forget all" is necessary.
> SwapCache handling is also necessary but I'd like to postpone until next set
> because it's complicated.
> 
> After above all.
>  - handle swap cache 
>  - Mem+Swap controller.
>  - add trashbox feature ?
>  - add memory.shrink_usage_to file.
> 
> It's long way to what I really want to do....
> 

Yes a long way to go, I want to add

1) Multi-hierarchy support
2) Support for soft-limits
3) get swappiness working (there are patches posted for it by Yamamoto-San, but
something is broken, I suspect even in global swappiness).



> 
> Thanks,
> -Kame


-- 
	Balbir

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Re: [PATCH 0/12] memcg updates v5

[KAMEZAWA Hiroyuki]

On Mon, 29 Sep 2008 08:32:07 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> KAMEZAWA Hiroyuki wrote:
> > On Fri, 26 Sep 2008 19:36:02 +0900
> > KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > 
> >>> I think (1) might be OK, except for the accounting issues pointed out (change in
> >>> behaviour visible to end user again, sigh! :( ).
> >> But it was just a BUG from my point of view...
> >>
> >>> Is (1) a serious issue? 
> >> considering force_empty(), it's serious.
> >>
> >>> (2) seems OK, except for the locking change for mark_page_accessed. I am looking at
> >>> (4) and (6) currently.
> >>>
> > 
> > I'll do in following way in the next Monday.
> > Divide patches into 2 set
> > 
> > in early fix/optimize set.
> >   - push (2)
> >   - push (4)
> >   - push (6)
> >   - push (1)
> > 
> 
> Yes, sounds reasonable
> 
I'll just post this, today. 

> > drops (3).
> > 
> > I don't want to remove all? pages-never-on-LRU before fixing force_empty.
> > 
> > in updates
> >   - introduce atomic flags. (5)
> >   - add move_account() function (7)
> 
> without (3), don't we have a problem pushing (7)?
> 
I'll add -EBUSY behavior to force_empty.
I'm now adding(merging) code to move_account.patch for supporing force_empty.
It seems much clearer than v5.


> >   - add memory.attribute to each memcg dir. (NEW)
> >   - enhance force_empty (was (8))
> >        - remove "forget all" logic. and add attribute to select following 2 behavior
> >           - call try_to_free_page() until the usage goes down to 0.
> >             This allows faiulre (if page is mlocked, we can't do.). (NEW)
> >           - call move_account() to move all charges to its parent (as much as possible) (NEW)
> >           In future, I'd liket to add trash-box cgroup for force_empty somewhere.
> >   - allocate all page cgroup at boot (9)
> >   - lazy lru free/add (10,11) with fixes.
> >   - fix race at charging swap. (12)
> > 
> 
> I think (9) is probably the most important. I'll review it today
> 
Thanks. no major changes in my current stack from already posted one.

Thanks,
-Kame

> > After (9), all page and page_cgroup has one-to-one releationship and we want to
> > assume that "if page is alive and on LRU, it's accounted and has page_cgroup."
> > (other team, bio cgroup want to use page_cgroup and I want to make it easy.)
> > 
> > For this, fix to behavior of force_empty..."forget all" is necessary.
> > SwapCache handling is also necessary but I'd like to postpone until next set
> > because it's complicated.
> > 
> > After above all.
> >  - handle swap cache 
> >  - Mem+Swap controller.
> >  - add trashbox feature ?
> >  - add memory.shrink_usage_to file.
> > 
> > It's long way to what I really want to do....
> > 
> 
> Yes a long way to go, I want to add
> 
> 1) Multi-hierarchy support
> 2) Support for soft-limits
> 3) get swappiness working (there are patches posted for it by Yamamoto-San, but
> something is broken, I suspect even in global swappiness).
> 
> 
> 
> > 
> > Thanks,
> > -Kame
> 
> 
> -- 
> 	Balbir
> 

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