Hi Andrew,

As Johannes pointed out, TestClearPageCgroupAcctLRU prevent wrong
counting and triggering VM_BUG_ON.
Apparently it is unnecessary call but it doesn't happen the problem so
I think it's not a material of stable.

I will resend modified description.
Sorry for confusing you by wrong description.

On Wed, Dec 8, 2010 at 6:53 AM,  <[email protected]> wrote:
>
> The patch titled
>     mm/compaction.c: avoid double mem_cgroup_del_lru()
> has been added to the -mm tree.  Its filename is
>     mm-compactionc-avoid-double-mem_cgroup_del_lru.patch
>
> Before you just go and hit "reply", please:
>   a) Consider who else should be cc'ed
>   b) Prefer to cc a suitable mailing list as well
>   c) Ideally: find the original patch on the mailing list and do a
>      reply-to-all to that, adding suitable additional cc's
>
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
>
> See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
> out what to do about this
>
> The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
>
> ------------------------------------------------------
> Subject: mm/compaction.c: avoid double mem_cgroup_del_lru()
> From: Minchan Kim <[email protected]>
>
> del_page_from_lru_list() already called mem_cgroup_del_lru().  So we must
> not call it again.  It breaks memcg stats accounting and can trigger a
> VM_BUG_ON().
>
> Signed-off-by: Minchan Kim <[email protected]>
> Cc: Balbir Singh <[email protected]>
> Cc: KAMEZAWA Hiroyuki <[email protected]>
> Cc: Mel Gorman <[email protected]>
> Cc: <[email protected]>
> Signed-off-by: Andrew Morton <[email protected]>
> ---
>
>  mm/compaction.c |    1 -
>  1 file changed, 1 deletion(-)
>
> diff -puN mm/compaction.c~mm-compactionc-avoid-double-mem_cgroup_del_lru 
> mm/compaction.c
> --- a/mm/compaction.c~mm-compactionc-avoid-double-mem_cgroup_del_lru
> +++ a/mm/compaction.c
> @@ -279,7 +279,6 @@ static unsigned long isolate_migratepage
>                /* Successfully isolated */
>                del_page_from_lru_list(zone, page, page_lru(page));
>                list_add(&page->lru, migratelist);
> -               mem_cgroup_del_lru(page);
>                cc->nr_migratepages++;
>
>                /* Avoid isolating too much */
> _
>
> Patches currently in -mm which might be from [email protected] are
>
> linux-next.patch
> mm-compactionc-avoid-double-mem_cgroup_del_lru.patch
> mm-vmap-area-cache.patch
> mm-find_get_pages_contig-fixlet.patch
> mm-deactivate-invalidated-pages.patch
> mm-deactivate-invalidated-pages-fix.patch
> memcg-add-page_cgroup-flags-for-dirty-page-tracking.patch
> memcg-document-cgroup-dirty-memory-interfaces.patch
> memcg-document-cgroup-dirty-memory-interfaces-fix.patch
> memcg-create-extensible-page-stat-update-routines.patch
> memcg-add-lock-to-synchronize-page-accounting-and-migration.patch
> memcg-remove-unnecessary-return-from-void-returning-mem_cgroup_del_lru_list.patch
> memcg-use-zalloc-rather-than-mallocmemset.patch
>
>



-- 
Kind regards,
Minchan Kim

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