diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
index 4eb05302e2e1..5524e8bd7437 100644
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -475,7 +475,7 @@ int swap_cgroup_swapon(int type, unsigned long max_pages)
 	if (!do_swap_account)
 		return 0;
 
-	length = ((max_pages/SC_PER_PAGE) + 1);
+	length = DIV_ROUND_UP(max_pages, SC_PER_PAGE);
 	array_size = length * sizeof(void *);
 
 	array = vmalloc(array_size);