1 files changed, 2 insertions, 3 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e44fb0fbb80e..575203ae2109 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1024,9 +1024,7 @@ static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page)
                 return NULL;
 
         pc = lookup_page_cgroup(page);
-        /*
-         * Used bit of swapcache is solid under page lock.
-         */
+        lock_page_cgroup(pc);
         if (PageCgroupUsed(pc)) {
                 mem = pc->mem_cgroup;
                 if (mem && !css_tryget(&mem->css))
@@ -1040,6 +1038,7 @@ static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page)
                         mem = NULL;
                 rcu_read_unlock();
         }
+        unlock_page_cgroup(pc);
         return mem;
 }