diff --git a/mm/ksm.c b/mm/ksm.c
index adb5f991da8e..7596e14bc233 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1318,10 +1318,10 @@ bool is_page_sharing_candidate(struct stable_node *stable_node)
 	return __is_page_sharing_candidate(stable_node, 0);
 }
 
-struct page *stable_node_dup(struct stable_node **_stable_node_dup,
-			     struct stable_node **_stable_node,
-			     struct rb_root *root,
-			     bool prune_stale_stable_nodes)
+static struct page *stable_node_dup(struct stable_node **_stable_node_dup,
+				    struct stable_node **_stable_node,
+				    struct rb_root *root,
+				    bool prune_stale_stable_nodes)
 {
 	struct stable_node *dup, *found = NULL, *stable_node = *_stable_node;
 	struct hlist_node *hlist_safe;