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memcg: fix memory migration of shmem swapcache

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In the current implementation mem_cgroup_end_migration() decides whether
the page migration has succeeded or not by checking "oldpage->mapping".

But if we are tring to migrate a shmem swapcache, the page->mapping of it
is NULL from the begining, so the check would be invalid.  As a result,
mem_cgroup_end_migration() assumes the migration has succeeded even if
it's not, so "newpage" would be freed while it's not uncharged.

This patch fixes it by passing mem_cgroup_end_migration() the result of
the page migration.

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Daisuke Nishimura
2011-01-13 15:47:43 -08:00
committed by Linus Torvalds
parent 17295c88a1
commit 50de1dd967
3 changed files with 5 additions and 7 deletions
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2
mm/migrate.c
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@@ -768,7 +768,7 @@ skip_unmap:
uncharge:
if (!charge)
mem_cgroup_end_migration(mem, page, newpage);
mem_cgroup_end_migration(mem, page, newpage, rc == 0);
unlock:
unlock_page(page);