* Re: [PATCH] memcg: fix Bad page state after replace_page_cache
2012-04-19 6:34 [PATCH] memcg: fix Bad page state after replace_page_cache Hugh Dickins
@ 2012-04-19 10:20 ` Michal Hocko
2012-04-20 1:47 ` KAMEZAWA Hiroyuki
2012-04-24 18:22 ` Johannes Weiner
2 siblings, 0 replies; 5+ messages in thread
From: Michal Hocko @ 2012-04-19 10:20 UTC (permalink / raw)
To: Hugh Dickins
Cc: Linus Torvalds, Andrew Morton, Miklos Szeredi, KAMEZAWA Hiroyuki,
Johannes Weiner, linux-kernel, linux-mm
On Wed 18-04-12 23:34:46, Hugh Dickins wrote:
> My 9ce70c0240d0 "memcg: fix deadlock by inverting lrucare nesting" put a
> nasty little bug into v3.3's version of mem_cgroup_replace_page_cache(),
> sometimes used for FUSE. Replacing __mem_cgroup_commit_charge_lrucare()
> by __mem_cgroup_commit_charge(), I used the "pc" pointer set up earlier:
> but it's for oldpage, and needs now to be for newpage. Once oldpage was
> freed, its PageCgroupUsed bit (cleared above but set again here) caused
> "Bad page state" messages - and perhaps worse, being missed from newpage.
> (I didn't find this by using FUSE, but in reusing the function for tmpfs.)
>
> Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Thanks
> Cc: stable@vger.kernel.org [v3.3 only]
> ---
>
> mm/memcontrol.c | 1 +
> 1 file changed, 1 insertion(+)
>
> --- 3.4-rc3/mm/memcontrol.c 2012-04-15 20:47:37.151777506 -0700
> +++ linux/mm/memcontrol.c 2012-04-18 22:29:18.490639511 -0700
> @@ -3392,6 +3392,7 @@ void mem_cgroup_replace_page_cache(struc
> * the newpage may be on LRU(or pagevec for LRU) already. We lock
> * LRU while we overwrite pc->mem_cgroup.
> */
> + pc = lookup_page_cgroup(newpage);
> __mem_cgroup_commit_charge(memcg, newpage, 1, pc, type, true);
> }
>
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] memcg: fix Bad page state after replace_page_cache
2012-04-19 6:34 [PATCH] memcg: fix Bad page state after replace_page_cache Hugh Dickins
2012-04-19 10:20 ` Michal Hocko
@ 2012-04-20 1:47 ` KAMEZAWA Hiroyuki
2012-04-24 18:22 ` Johannes Weiner
2 siblings, 0 replies; 5+ messages in thread
From: KAMEZAWA Hiroyuki @ 2012-04-20 1:47 UTC (permalink / raw)
To: Hugh Dickins
Cc: Linus Torvalds, Andrew Morton, Miklos Szeredi, Johannes Weiner,
Michal Hocko, linux-kernel, linux-mm
(2012/04/19 15:34), Hugh Dickins wrote:
> My 9ce70c0240d0 "memcg: fix deadlock by inverting lrucare nesting" put a
> nasty little bug into v3.3's version of mem_cgroup_replace_page_cache(),
> sometimes used for FUSE. Replacing __mem_cgroup_commit_charge_lrucare()
> by __mem_cgroup_commit_charge(), I used the "pc" pointer set up earlier:
> but it's for oldpage, and needs now to be for newpage. Once oldpage was
> freed, its PageCgroupUsed bit (cleared above but set again here) caused
> "Bad page state" messages - and perhaps worse, being missed from newpage.
> (I didn't find this by using FUSE, but in reusing the function for tmpfs.)
>
> Signed-off-by: Hugh Dickins <hughd@google.com>
> Cc: stable@vger.kernel.org [v3.3 only]
Thanks,
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> ---
>
> mm/memcontrol.c | 1 +
> 1 file changed, 1 insertion(+)
>
> --- 3.4-rc3/mm/memcontrol.c 2012-04-15 20:47:37.151777506 -0700
> +++ linux/mm/memcontrol.c 2012-04-18 22:29:18.490639511 -0700
> @@ -3392,6 +3392,7 @@ void mem_cgroup_replace_page_cache(struc
> * the newpage may be on LRU(or pagevec for LRU) already. We lock
> * LRU while we overwrite pc->mem_cgroup.
> */
> + pc = lookup_page_cgroup(newpage);
> __mem_cgroup_commit_charge(memcg, newpage, 1, pc, type, true);
> }
>
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>
>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] memcg: fix Bad page state after replace_page_cache
2012-04-19 6:34 [PATCH] memcg: fix Bad page state after replace_page_cache Hugh Dickins
2012-04-19 10:20 ` Michal Hocko
2012-04-20 1:47 ` KAMEZAWA Hiroyuki
@ 2012-04-24 18:22 ` Johannes Weiner
2012-04-24 19:13 ` Hugh Dickins
2 siblings, 1 reply; 5+ messages in thread
From: Johannes Weiner @ 2012-04-24 18:22 UTC (permalink / raw)
To: Hugh Dickins
Cc: Linus Torvalds, Andrew Morton, Miklos Szeredi, KAMEZAWA Hiroyuki,
Michal Hocko, linux-kernel, linux-mm
On Wed, Apr 18, 2012 at 11:34:46PM -0700, Hugh Dickins wrote:
> My 9ce70c0240d0 "memcg: fix deadlock by inverting lrucare nesting" put a
> nasty little bug into v3.3's version of mem_cgroup_replace_page_cache(),
> sometimes used for FUSE. Replacing __mem_cgroup_commit_charge_lrucare()
> by __mem_cgroup_commit_charge(), I used the "pc" pointer set up earlier:
> but it's for oldpage, and needs now to be for newpage. Once oldpage was
> freed, its PageCgroupUsed bit (cleared above but set again here) caused
> "Bad page state" messages - and perhaps worse, being missed from newpage.
> (I didn't find this by using FUSE, but in reusing the function for tmpfs.)
>
> Signed-off-by: Hugh Dickins <hughd@google.com>
> Cc: stable@vger.kernel.org [v3.3 only]
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
This is the second bug of this nature and none of the callsites are
actually using the pc themselves, so we should probably move the pc
lookup into __mem_cgroup_commit_charge() itself.
---
From: Johannes Weiner <hannes@cmpxchg.org>
Subject: [patch] mm: memcg: move pc lookup point to commit_charge()
None of the callsites actually need the page_cgroup descriptor
themselves, so just pass the page and do the look up in there.
We already had two bugs (6568d4a 'mm: memcg: update the correct soft
limit tree during migration' and 'memcg: fix Bad page state after
replace_page_cache') where the passed page and pc were not referring
to the same page frame.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
mm/memcontrol.c | 17 +++++------------
1 files changed, 5 insertions(+), 12 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 884e936..1a28dd8 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2461,10 +2461,10 @@ struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
struct page *page,
unsigned int nr_pages,
- struct page_cgroup *pc,
enum charge_type ctype,
bool lrucare)
{
+ struct page_cgroup *pc = lookup_page_cgroup(page);
struct zone *uninitialized_var(zone);
bool was_on_lru = false;
bool anon;
@@ -2701,7 +2701,6 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
{
struct mem_cgroup *memcg = NULL;
unsigned int nr_pages = 1;
- struct page_cgroup *pc;
bool oom = true;
int ret;
@@ -2715,11 +2714,10 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
oom = false;
}
- pc = lookup_page_cgroup(page);
ret = __mem_cgroup_try_charge(mm, gfp_mask, nr_pages, &memcg, oom);
if (ret == -ENOMEM)
return ret;
- __mem_cgroup_commit_charge(memcg, page, nr_pages, pc, ctype, false);
+ __mem_cgroup_commit_charge(memcg, page, nr_pages, ctype, false);
return 0;
}
@@ -2816,16 +2814,13 @@ static void
__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg,
enum charge_type ctype)
{
- struct page_cgroup *pc;
-
if (mem_cgroup_disabled())
return;
if (!memcg)
return;
cgroup_exclude_rmdir(&memcg->css);
- pc = lookup_page_cgroup(page);
- __mem_cgroup_commit_charge(memcg, page, 1, pc, ctype, true);
+ __mem_cgroup_commit_charge(memcg, page, 1, ctype, true);
/*
* Now swap is on-memory. This means this page may be
* counted both as mem and swap....double count.
@@ -3254,14 +3249,13 @@ int mem_cgroup_prepare_migration(struct page *page,
* page. In the case new page is migrated but not remapped, new page's
* mapcount will be finally 0 and we call uncharge in end_migration().
*/
- pc = lookup_page_cgroup(newpage);
if (PageAnon(page))
ctype = MEM_CGROUP_CHARGE_TYPE_MAPPED;
else if (page_is_file_cache(page))
ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
else
ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
- __mem_cgroup_commit_charge(memcg, newpage, 1, pc, ctype, false);
+ __mem_cgroup_commit_charge(memcg, newpage, 1, ctype, false);
return ret;
}
@@ -3348,8 +3342,7 @@ void mem_cgroup_replace_page_cache(struct page *oldpage,
* the newpage may be on LRU(or pagevec for LRU) already. We lock
* LRU while we overwrite pc->mem_cgroup.
*/
- pc = lookup_page_cgroup(newpage);
- __mem_cgroup_commit_charge(memcg, newpage, 1, pc, type, true);
+ __mem_cgroup_commit_charge(memcg, newpage, 1, type, true);
}
#ifdef CONFIG_DEBUG_VM
--
1.7.7.6
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 5+ messages in thread