From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

This rollback should be done at failure.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Paul Menage <menage@google.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memcontrol.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff -puN mm/memcontrol.c~memcg-remove-refcnt-from-page_cgroup-fix mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-remove-refcnt-from-page_cgroup-fix
+++ a/mm/memcontrol.c
@@ -762,8 +762,8 @@ int mem_cgroup_prepare_migration(struct 
 /* remove redundant charge if migration failed*/
 void mem_cgroup_end_migration(struct page *newpage)
 {
-	/* At success, page->mapping is not NULL */
-	if (newpage->mapping)
+	/* At success, page->mapping is not NULL and nothing to do. */
+	if (!newpage->mapping)
 		__mem_cgroup_uncharge_common(newpage,
 					 MEM_CGROUP_CHARGE_TYPE_FORCE);
 }
_