diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d02e9166255fbe78393138b98d53d3e4d799f0fe..d9467b38e2f714badb95d3806905846e6fce7ed5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4252,7 +4252,7 @@ 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);