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authorDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>2011-01-14 02:47:43 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-14 04:32:51 +0300
commit50de1dd967d4ba3b8a90ebe7a4f5feca24191317 (patch)
treeed2aa4352ae3c2887a90ef6279588a7048397d1b /mm/memcontrol.c
parent17295c88a160c6eea3fcf46cec9d08a0fcb02db9 (diff)
downloadlinux-50de1dd967d4ba3b8a90ebe7a4f5feca24191317.tar.xz
memcg: fix memory migration of shmem swapcache
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>
Diffstat (limited to 'mm/memcontrol.c')
-rw-r--r--mm/memcontrol.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6424ba0fce83..8ab841031436 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2896,7 +2896,7 @@ int mem_cgroup_prepare_migration(struct page *page,
/* remove redundant charge if migration failed*/
void mem_cgroup_end_migration(struct mem_cgroup *mem,
- struct page *oldpage, struct page *newpage)
+ struct page *oldpage, struct page *newpage, bool migration_ok)
{
struct page *used, *unused;
struct page_cgroup *pc;
@@ -2905,8 +2905,7 @@ void mem_cgroup_end_migration(struct mem_cgroup *mem,
return;
/* blocks rmdir() */
cgroup_exclude_rmdir(&mem->css);
- /* at migration success, oldpage->mapping is NULL. */
- if (oldpage->mapping) {
+ if (!migration_ok) {
used = oldpage;
unused = newpage;
} else {