diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e2f26991fff136ed40438f3b07cdaffec78aa90a..8add7daf98b0ace1c5e9f35041cef57362d15d55 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2706,7 +2706,7 @@ static int zone_batchsize(struct zone *zone)
 	 * of pages of one half of the possible page colors
 	 * and the other with pages of the other colors.
 	 */
-	batch = (1 << (fls(batch + batch/2)-1)) - 1;
+	batch = rounddown_pow_of_two(batch + batch/2) - 1;
 
 	return batch;
 }