From e7bbcdf3747e3919c31cfa87853c69d178bce548 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <error27@gmail.com>
Date: Tue, 23 Mar 2010 13:35:12 -0700
Subject: memcontrol: fix potential null deref

There was a potential null deref introduced in c62b1a3b31b5 ("memcg: use
generic percpu instead of private implementation").

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 00dda35..9ed760d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3691,8 +3691,10 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
 	else
 		mem = vmalloc(size);
 
-	if (mem)
-		memset(mem, 0, size);
+	if (!mem)
+		return NULL;
+
+	memset(mem, 0, size);
 	mem->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
 	if (!mem->stat) {
 		if (size < PAGE_SIZE)
-- 
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