diff --git a/[refs] b/[refs]
index 541bda67133a..7068ae048d11 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 0eb253e223c88b982461e59154fcad1b82597592
+refs/heads/master: 068b38c1fa7a9210608f27ac521897ccc5f9b726
diff --git a/trunk/mm/memcontrol.c b/trunk/mm/memcontrol.c
index f0dc076adf05..4d0ea3ceba6d 100644
--- a/trunk/mm/memcontrol.c
+++ b/trunk/mm/memcontrol.c
@@ -1992,6 +1992,7 @@ static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
 	struct mem_cgroup *parent;
+
 	if (val > 100)
 		return -EINVAL;
 
@@ -1999,15 +2000,22 @@ static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
 		return -EINVAL;
 
 	parent = mem_cgroup_from_cont(cgrp->parent);
+
+	cgroup_lock();
+
 	/* If under hierarchy, only empty-root can set this value */
 	if ((parent->use_hierarchy) ||
-	    (memcg->use_hierarchy && !list_empty(&cgrp->children)))
+	    (memcg->use_hierarchy && !list_empty(&cgrp->children))) {
+		cgroup_unlock();
 		return -EINVAL;
+	}
 
 	spin_lock(&memcg->reclaim_param_lock);
 	memcg->swappiness = val;
 	spin_unlock(&memcg->reclaim_param_lock);
 
+	cgroup_unlock();
+
 	return 0;
 }