memcg: use rcu_dereference to access mm->owner
mm->owner should be accessed with rcu_dereference().
Reported-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 18146c9..a9e3b76 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -75,7 +75,7 @@
{
struct mem_cgroup *mem;
rcu_read_lock();
- mem = mem_cgroup_from_task((mm)->owner);
+ mem = mem_cgroup_from_task(rcu_dereference((mm)->owner));
rcu_read_unlock();
return cgroup == mem;
}