From 574c4553bbf4da85697ee4591824c4334afaba66 Mon Sep 17 00:00:00 2001
From: Glauber Costa <glommer@parallels.com>
Date: Tue, 31 Jul 2012 16:43:07 -0700
Subject: [PATCH] --- yaml --- r: 320796 b: refs/heads/master c:
 567fb435bb7a37afda35902b884562c40756dc45 h: refs/heads/master v: v3

---
 [refs]                | 2 +-
 trunk/mm/memcontrol.c | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 896dfc1e0170..30dade25fee8 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: ca28ddc908fcfef0e5c1b6e5df632db7fc26de10
+refs/heads/master: 567fb435bb7a37afda35902b884562c40756dc45
diff --git a/trunk/mm/memcontrol.c b/trunk/mm/memcontrol.c
index 55a85e1a342f..6d3dd54ec429 100644
--- a/trunk/mm/memcontrol.c
+++ b/trunk/mm/memcontrol.c
@@ -3764,6 +3764,10 @@ static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
 		parent_memcg = mem_cgroup_from_cont(parent);
 
 	cgroup_lock();
+
+	if (memcg->use_hierarchy == val)
+		goto out;
+
 	/*
 	 * If parent's use_hierarchy is set, we can't make any modifications
 	 * in the child subtrees. If it is unset, then the change can
@@ -3780,6 +3784,8 @@ static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
 			retval = -EBUSY;
 	} else
 		retval = -EINVAL;
+
+out:
 	cgroup_unlock();
 
 	return retval;