diff --git a/[refs] b/[refs]
index d0df0a4aa4cb..413f6dadcb02 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: c26251f9f06d27d1941229d237aca44a0e7b4e42
+refs/heads/master: d842301181d9a4486aa24720ed4f96018b213292
diff --git a/trunk/mm/memcontrol.c b/trunk/mm/memcontrol.c
index 07d92b84f448..916132a29b36 100644
--- a/trunk/mm/memcontrol.c
+++ b/trunk/mm/memcontrol.c
@@ -2715,9 +2715,7 @@ static int mem_cgroup_move_parent(struct page *page,
 	unsigned long uninitialized_var(flags);
 	int ret;
 
-	/* Is ROOT ? */
-	if (mem_cgroup_is_root(child))
-		return -EINVAL;
+	VM_BUG_ON(mem_cgroup_is_root(child));
 
 	ret = -EBUSY;
 	if (!get_page_unless_zero(page))
@@ -3823,6 +3821,8 @@ static int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
 	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
 	int ret;
 
+	if (mem_cgroup_is_root(memcg))
+		return -EINVAL;
 	css_get(&memcg->css);
 	ret = mem_cgroup_force_empty(memcg);
 	css_put(&memcg->css);