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>

1 files changed, 9 insertions, 7 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9a99cfaf0a19..2efa8ea07ff7 100644
--- 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;
 }
 
 /*