[PATCH] memcg: update patch set v7

[PATCH] memcg: update patch set v7

[KAMEZAWA Hiroyuki]

Hi, Andrew. please allow me to test under -mm if ok.

This series is against the newest -mmotm(stamp-2008-10-02-16-17)
and I think ready-to-go.

All comments are reflected.
(and CONFIG_CGROUP_MEM_RES_CTLR=n case is fixed.)

Including following patches.

[1/6] ... account swap cache under lock
[2/6] ... set page->mapping to be NULL before uncharge
[3/6] ... avoid to account not-on-LRU pages.
[4/6] ... optimize per cpu statistics on memcg.
[5/6] ... make page_cgroup->flags atomic.
[6/6] ... allocate page_cgroup at boot.

I did tests I can. But I think patch 6/6 needs wider testers.
It has some dependency to configs/archs.

(*) the newest mmotm needs some patches to be driven.

Thanks,
-Kame

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[PATCH 1/6] memcg: move charge swapin under lock

[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.
I don't see any bad problem *now* but this fix will be good for future
for avoiding unneccesary racy state.


Changelog: (v6) -> (v7)
 - no changes.
Changelog: (v5) -> (v6)
 - mark_page_accessed() is moved before lock_page().
 - fixed missing unlock_page()
(no changes in previous version)

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> 


 mm/memory.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 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
@@ -2326,16 +2326,17 @@ static int do_swap_page(struct mm_struct
 		count_vm_event(PGMAJFAULT);
 	}
 
+	mark_page_accessed(page);
+
+	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;
+		unlock_page(page);
 		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.
 	 */

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[PATCH 2/6] memcg: make page->mapping NULL before 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>
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>



 mm/filemap.c    |    2 +-
 mm/memcontrol.c |    1 +
 mm/migrate.c    |    9 +++++++--
 3 files changed, 9 insertions(+), 3 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
@@ -734,6 +734,7 @@ 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;
 }
@@ -341,6 +339,8 @@ static int migrate_page_move_mapping(str
  */
 static void migrate_page_copy(struct page *newpage, struct page *page)
 {
+	int anon;
+
 	copy_highpage(newpage, page);
 
 	if (PageError(page))
@@ -378,8 +378,13 @@ static void migrate_page_copy(struct pag
 #endif
 	ClearPagePrivate(page);
 	set_page_private(page, 0);
+	/* page->mapping contains a flag for PageAnon() */
+	anon = PageAnon(page);
 	page->mapping = NULL;
 
+	if (!anon) /* This page was removed from radix-tree. */
+		mem_cgroup_uncharge_cache_page(page);
+
 	/*
 	 * If any waiters have accumulated on the new page then
 	 * wake them up.

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[PATCH 3/6] memcg: avoid accounting special pages

[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.

Changelog: v6 -> v7
  - style fix.
Changelog: v5 -> v6
  - modified Documentation.
  - fixed to charge only when a page is newly allocated.

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

 Documentation/controllers/memory.txt |   24 ++++++++++++++++--------
 mm/memory.c                          |   25 +++++++++++--------------
 mm/rmap.c                            |    4 ++--
 3 files changed, 29 insertions(+), 24 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
@@ -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;
 }
@@ -2463,6 +2457,7 @@ static int __do_fault(struct mm_struct *
 	struct page *page;
 	pte_t entry;
 	int anon = 0;
+	int charged = 0;
 	struct page *dirty_page = NULL;
 	struct vm_fault vmf;
 	int ret;
@@ -2503,6 +2498,12 @@ static int __do_fault(struct mm_struct *
 				ret = VM_FAULT_OOM;
 				goto out;
 			}
+			if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
+				ret = VM_FAULT_OOM;
+				page_cache_release(page);
+				goto out;
+			}
+			charged = 1;
 			/*
 			 * Don't let another task, with possibly unlocked vma,
 			 * keep the mlocked page.
@@ -2543,11 +2544,6 @@ static int __do_fault(struct mm_struct *
 
 	}
 
-	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
-		ret = VM_FAULT_OOM;
-		goto out;
-	}
-
 	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
 
 	/*
@@ -2585,7 +2581,8 @@ 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 (charged)
+			mem_cgroup_uncharge_page(page);
 		if (anon)
 			page_cache_release(page);
 		else
Index: mmotm-2.6.27-rc7+/mm/rmap.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/rmap.c
+++ mmotm-2.6.27-rc7+/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);
 		/*
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
@@ -112,14 +112,22 @@ the per cgroup LRU.
 
 2.2.1 Accounting details
 
-All mapped pages (RSS) and unmapped user pages (Page Cache) are accounted.
-RSS pages are accounted at the time of page_add_*_rmap() unless they've already
-been accounted for earlier. A file page will be accounted for as Page Cache;
-it's mapped into the page tables of a process, duplicate accounting is carefully
-avoided. Page Cache pages are accounted at the time of add_to_page_cache().
-The corresponding routines that remove a page from the page tables or removes
-a page from Page Cache is used to decrement the accounting counters of the
-cgroup.
+All mapped anon pages (RSS) and cache pages (Page Cache) are accounted.
+(some pages which never be reclaimable and will not be on global LRU
+ are not accounted. we just accounts pages under usual vm management.)
+
+RSS pages are accounted at page_fault unless they've already been accounted
+for earlier. A file page will be accounted for as Page Cache when it's
+inserted into inode (radix-tree). While it's mapped into the page tables of
+processes, duplicate accounting is carefully avoided.
+
+A RSS page is unaccounted when it's fully unmapped. A PageCache page is
+unaccounted when it's removed from radix-tree.
+
+At page migration, accounting information is kept.
+
+Note: we just account pages-on-lru because our purpose is to control amount
+of used pages. not-on-lru pages are tend to be out-of-control from vm view.
 
 2.3 Shared Page Accounting
 

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[PATCH 4/6] memcg: optimize per-cpu statistics

[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.

Changlog: v5->v6
 - patch series was reordered and needs some adjustment. no changes in logic.
Changelog v3->v4:
 - merged with an other leaf patch.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.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,
@@ -190,18 +189,21 @@ 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 (flags & PAGE_CGROUP_FLAG_CACHE)
-		__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);
 }
 
@@ -558,7 +560,7 @@ 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;
 

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[PATCH 5/6] memcg: atomic ops for page_cgroup->flags

[KAMEZAWA Hiroyuki]

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

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.
For example, we'll place LOCK bit on flags field. We need atomic operation
to modify LRU bit without LOCK.
 
Changelog: (v5) -> (v7)
 - no changes.

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>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.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
@@ -157,12 +157,46 @@ 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)
 {
@@ -177,15 +211,25 @@ 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;
@@ -194,7 +238,7 @@ static void mem_cgroup_charge_statistics
 	VM_BUG_ON(!irqs_disabled());
 
 	cpustat = &stat->cpustat[smp_processor_id()];
-	if (flags & PAGE_CGROUP_FLAG_CACHE)
+	if (PageCgroupCache(pc))
 		__mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_CACHE, val);
 	else
 		__mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_RSS, val);
@@ -295,18 +339,18 @@ 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);
 }
 
@@ -315,27 +359,27 @@ 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);
 
@@ -343,16 +387,20 @@ 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;
@@ -589,16 +637,7 @@ 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))) {
@@ -677,8 +716,12 @@ 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);
 }
 
 /*
@@ -706,8 +749,7 @@ __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);
@@ -758,7 +800,7 @@ 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

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[PATCH 6/6] 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.)

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.

Changelog: v6 -> v7:
 * adjusted to change in mm.
 * added lru_add_drain_all() to force_empty()
   (newly allocated pages can be not on LRU before force_empty())
 * CONFIG_CGROUP_MEM_RES_CTLR=n case fix.

Changelog: v5 -> v6.
 * reflected comments.
 * coding style fixes.
 * 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>
Reviewed-by: Balbir Singh <balbir@linux.vnet.ibm.com>

 include/linux/memcontrol.h  |   11 -
 include/linux/mm_types.h    |    3 
 include/linux/mmzone.h      |   14 ++
 include/linux/page_cgroup.h |   90 ++++++++++++++++
 mm/Makefile                 |    2 
 mm/memcontrol.c             |  247 ++++++++++++++------------------------------
 mm/page_alloc.c             |   12 --
 mm/page_cgroup.c            |  237 ++++++++++++++++++++++++++++++++++++++++++
 8 files changed, 425 insertions(+), 191 deletions(-)

Index: mmotm-2.6.27-rc8+/mm/page_cgroup.c
===================================================================
--- /dev/null
+++ mmotm-2.6.27-rc8+/mm/page_cgroup.c
@@ -0,0 +1,237 @@
+#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;
+
+#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(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage);
+	printk(KERN_INFO "please try cgroup_disable=memory option if you"
+	" don't want\n");
+	return;
+fail:
+	printk(KERN_CRIT "allocation of page_cgroup was failed.\n");
+	printk(KERN_CRIT "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(KERN_ERR "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(KERN_CRIT "try cgroup_disable=memory boot option\n");
+		panic("Out of memory");
+	} else {
+		hotplug_memory_notifier(page_cgroup_callback, 0);
+	}
+	printk(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage);
+	printk(KERN_INFO "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-rc8+/mm/Makefile
===================================================================
--- mmotm-2.6.27-rc8+.orig/mm/Makefile
+++ mmotm-2.6.27-rc8+/mm/Makefile
@@ -33,6 +33,6 @@ 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-rc8+/include/linux/page_cgroup.h
===================================================================
--- /dev/null
+++ mmotm-2.6.27-rc8+/include/linux/page_cgroup.h
@@ -0,0 +1,103 @@
+#ifndef __LINUX_PAGE_CGROUP_H
+#define __LINUX_PAGE_CGROUP_H
+
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+#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);
+}
+
+#else /* CONFIG_CGROUP_MEM_RES_CTLR */
+struct page_cgroup;
+
+static inline void pgdat_page_cgroup_init(struct pglist_data *pgdat)
+{
+}
+
+static inline struct page_cgroup *lookup_page_cgroup(struct page *page)
+{
+	return NULL;
+}
+#endif
+#endif
Index: mmotm-2.6.27-rc8+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc8+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc8+/mm/memcontrol.c
@@ -33,11 +33,11 @@
 #include <linux/seq_file.h>
 #include <linux/vmalloc.h>
 #include <linux/mm_inline.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
 
 /*
@@ -135,79 +135,6 @@ struct mem_cgroup {
 };
 static struct mem_cgroup 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,
@@ -216,12 +143,18 @@ enum charge_type {
 	NR_CHARGE_TYPE,
 };
 
+/* only for here (for easy reading.) */
+#define PCGF_CACHE	(1UL << PCG_CACHE)
+#define PCGF_USED	(1UL << PCG_USED)
+#define PCGF_ACTIVE	(1UL << PCG_ACTIVE)
+#define PCGF_LOCK	(1UL << PCG_LOCK)
+#define PCGF_FILE	(1UL << PCG_FILE)
 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,
+	PCGF_CACHE | PCGF_FILE | PCGF_USED | PCGF_LOCK, /* File Cache */
+	PCGF_ACTIVE | PCGF_USED | PCGF_LOCK, /* Anon */
+	PCGF_ACTIVE | PCGF_CACHE | PCGF_USED | PCGF_LOCK, /* Shmem */
+	0, /* FORCE */
 };
 
 /*
@@ -303,37 +236,6 @@ 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)
 {
@@ -436,17 +338,16 @@ 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 (pc && PageCgroupUsed(pc)) {
 		mz = page_cgroup_zoneinfo(pc);
 		spin_lock_irqsave(&mz->lru_lock, flags);
 		__mem_cgroup_move_lists(pc, lru);
 		spin_unlock_irqrestore(&mz->lru_lock, flags);
 	}
-	unlock_page_cgroup(page);
+	unlock_page_cgroup(pc);
 }
 
 /*
@@ -533,6 +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)))
@@ -576,26 +479,27 @@ 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;
 		}
 		/*
@@ -631,36 +535,33 @@ static int mem_cgroup_charge_common(stru
 		}
 	}
 
+
+	lock_page_cgroup(pc);
+	if (unlikely(PageCgroupUsed(pc))) {
+		unlock_page_cgroup(pc);
+		res_counter_uncharge(&mem->res, PAGE_SIZE);
+		css_put(&mem->css);
+
+		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);
 
-	unlock_page_cgroup(page);
 done:
 	return 0;
 out:
 	css_put(&mem->css);
-	kmem_cache_free(page_cgroup_cache, pc);
-err:
 	return -ENOMEM;
 }
 
@@ -668,7 +569,8 @@ 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.
@@ -689,7 +591,8 @@ 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
@@ -702,15 +605,16 @@ 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))
@@ -741,37 +645,39 @@ __mem_cgroup_uncharge_common(struct 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;
 
-	if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
-	    && ((PageCgroupCache(pc) || page_mapped(page))))
-		goto unlock;
+	lock_page_cgroup(pc);
+	if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED && page_mapped(page))
+	     || !PageCgroupUsed(pc)) {
+		/* This happens at race in zap_pte_range() and do_swap_page()*/
+		unlock_page_cgroup(pc);
+		return;
+	}
+	ClearPageCgroupUsed(pc);
+	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);
+	unlock_page_cgroup(pc);
 
-	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);
 
-	kmem_cache_free(page_cgroup_cache, pc);
 	return;
-unlock:
-	unlock_page_cgroup(page);
 }
 
 void mem_cgroup_uncharge_page(struct page *page)
 {
+	/* early check. */
+	if (page_mapped(page))
+		return;
+	if (page->mapping && !PageAnon(page))
+		return;
 	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
 }
 
@@ -795,9 +701,9 @@ 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)) {
@@ -807,7 +713,7 @@ 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);
@@ -832,7 +738,7 @@ void mem_cgroup_end_migration(struct pag
 	 */
 	if (!newpage->mapping)
 		__mem_cgroup_uncharge_common(newpage,
-					 MEM_CGROUP_CHARGE_TYPE_FORCE);
+				MEM_CGROUP_CHARGE_TYPE_FORCE);
 	else if (PageAnon(newpage))
 		mem_cgroup_uncharge_page(newpage);
 }
@@ -918,6 +824,8 @@ static void mem_cgroup_force_empty_list(
 	while (!list_empty(list)) {
 		pc = list_entry(list->prev, struct page_cgroup, lru);
 		page = pc->page;
+		if (!PageCgroupUsed(pc))
+			break;
 		get_page(page);
 		spin_unlock_irqrestore(&mz->lru_lock, flags);
 		/*
@@ -932,8 +840,10 @@ static void mem_cgroup_force_empty_list(
 				count = FORCE_UNCHARGE_BATCH;
 				cond_resched();
 			}
-		} else
-			cond_resched();
+		} else {
+			spin_lock_irqsave(&mz->lru_lock, flags);
+			break;
+		}
 		spin_lock_irqsave(&mz->lru_lock, flags);
 	}
 	spin_unlock_irqrestore(&mz->lru_lock, flags);
@@ -957,6 +867,8 @@ static int mem_cgroup_force_empty(struct
 	while (mem->res.usage > 0) {
 		if (atomic_read(&mem->css.cgroup->count) > 0)
 			goto out;
+		/* This is for making all *used* pages to be on LRU. */
+		lru_add_drain_all();
 		for_each_node_state(node, N_POSSIBLE)
 			for (zid = 0; zid < MAX_NR_ZONES; zid++) {
 				struct mem_cgroup_per_zone *mz;
@@ -965,6 +877,7 @@ static int mem_cgroup_force_empty(struct
 				for_each_lru(l)
 					mem_cgroup_force_empty_list(mem, mz, l);
 			}
+		cond_resched();
 	}
 	ret = 0;
 out:
@@ -1175,8 +1088,8 @@ 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-rc8+/mm/page_alloc.c
===================================================================
--- mmotm-2.6.27-rc8+.orig/mm/page_alloc.c
+++ mmotm-2.6.27-rc8+/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();
@@ -475,7 +470,6 @@ 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);
@@ -612,7 +606,6 @@ 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);
@@ -3498,6 +3491,7 @@ 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-rc8+/include/linux/mmzone.h
===================================================================
--- mmotm-2.6.27-rc8+.orig/include/linux/mmzone.h
+++ mmotm-2.6.27-rc8+/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-rc8+/include/linux/memcontrol.h
===================================================================
--- mmotm-2.6.27-rc8+.orig/include/linux/memcontrol.h
+++ mmotm-2.6.27-rc8+/include/linux/memcontrol.h
@@ -27,9 +27,6 @@ struct mm_struct;
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 
-#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 +69,8 @@ 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)
 {
Index: mmotm-2.6.27-rc8+/include/linux/mm_types.h
===================================================================
--- mmotm-2.6.27-rc8+.orig/include/linux/mm_types.h
+++ mmotm-2.6.27-rc8+/include/linux/mm_types.h
@@ -94,9 +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_PAGE_OWNER
 	int order;
 	unsigned int gfp_mask;

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Re: [PATCH] memcg: update patch set v7

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> Hi, Andrew. please allow me to test under -mm if ok.
> 
> This series is against the newest -mmotm(stamp-2008-10-02-16-17)
> and I think ready-to-go.
> 
> All comments are reflected.
> (and CONFIG_CGROUP_MEM_RES_CTLR=n case is fixed.)
> 
> Including following patches.
> 
> [1/6] ... account swap cache under lock
> [2/6] ... set page->mapping to be NULL before uncharge
> [3/6] ... avoid to account not-on-LRU pages.
> [4/6] ... optimize per cpu statistics on memcg.
> [5/6] ... make page_cgroup->flags atomic.
> [6/6] ... allocate page_cgroup at boot.
> 
> I did tests I can. But I think patch 6/6 needs wider testers.
> It has some dependency to configs/archs.
> 
> (*) the newest mmotm needs some patches to be driven.

Kamezawa-San,

Thanks for the patchset. I would like to see these tested in -mm as well. The
complaint that I am hearing from Fedora is that for them to enable the memory
controller, they would like to see the struct page overhead go (for 32 bit
systems that have 32 byte cachelines). This series helps us address that issue
and helps with performance.

-- 
	Balbir

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