memcg: null dereference on allocation failure

The original code had a null dereference if alloc_percpu() failed.  This
was introduced in commit 711d3d2c9bc3 ("memcg: cpu hotplug aware percpu
count updates")

Signed-off-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
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 9a99cfa..2efa8ea 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4208,15 +4208,17 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
 
        memset(mem, 0, size);
        mem->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
-       if (!mem->stat) {
-               if (size < PAGE_SIZE)
-                       kfree(mem);
-               else
-                       vfree(mem);
-               mem = NULL;
-       }
+       if (!mem->stat)
+               goto out_free;
        spin_lock_init(&mem->pcp_counter_lock);
        return mem;
+
+out_free:
+       if (size < PAGE_SIZE)
+               kfree(mem);
+       else
+               vfree(mem);
+       return NULL;
 }
 
 /*