diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 606a481afe2e2e587115f7228b949cf2cf008c7f..9f86404b37142ee4bba65945df81f4e4831dde0e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4537,7 +4537,7 @@ static void memcg_swap_device_init(struct mem_cgroup *memcg,
 	}
 }
 
-u64 memcg_swapmax_read(struct cgroup_subsys_state *css, struct cftype *cft)
+static u64 memcg_swapmax_read(struct cgroup_subsys_state *css, struct cftype *cft)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);