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 00dda352144c962468443241bfe564b06b933b2f..9ed760dc74481a7436e3ab7b084ff8abd233ee01 100644 (file)
--- 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)