diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c31a310aa146..e0c2066495e3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1737,11 +1737,12 @@ int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
 		goto charge_cur_mm;
 	/*
 	 * A racing thread's fault, or swapoff, may have already updated
-	 * the pte, and even removed page from swap cache: return success
-	 * to go on to do_swap_page()'s pte_same() test, which should fail.
+	 * the pte, and even removed page from swap cache: in those cases
+	 * do_swap_page()'s pte_same() test will fail; but there's also a
+	 * KSM case which does need to charge the page.
 	 */
 	if (!PageSwapCache(page))
-		return 0;
+		goto charge_cur_mm;
 	mem = try_get_mem_cgroup_from_swapcache(page);
 	if (!mem)
 		goto charge_cur_mm;