diff --git a/mm/vmscan.c b/mm/vmscan.c
index 3d4aa160f517a5f42425fea5bf361989e6241313..5e9434b2896f2b760b3c93d9d7b67c7b33ab6af9 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4363,7 +4363,7 @@ static unsigned long purgeable_node(pg_data_t *pgdata, struct scan_control *sc)
 	struct mem_cgroup *memcg = NULL;
 	unsigned long nr = 0;
 #ifdef CONFIG_MEMCG
-	while (memcg = mem_cgroup_iter(NULL, memcg, NULL))
+	while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)))
 #endif
 	{
 		struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdata);