Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752148AbaGKISe (ORCPT ); Fri, 11 Jul 2014 04:18:34 -0400 Received: from relay.parallels.com ([195.214.232.42]:54122 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750767AbaGKISc (ORCPT ); Fri, 11 Jul 2014 04:18:32 -0400 Subject: [PATCH] mm/page-writeback.c: fix divide by zero in bdi_dirty_limits To: akpm@linux-foundation.org From: Maxim Patlasov Cc: riel@redhat.com, linux-kernel@vger.kernel.org, mhocko@suse.cz, linux-mm@kvack.org, kosaki.motohiro@jp.fujitsu.com, fengguang.wu@intel.com, jweiner@redhat.com Date: Fri, 11 Jul 2014 12:18:27 +0400 Message-ID: <20140711081656.15654.19946.stgit@localhost.localdomain> User-Agent: StGit/0.16 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Under memory pressure, it is possible for dirty_thresh, calculated by global_dirty_limits() in balance_dirty_pages(), to equal zero. Then, if strictlimit is true, bdi_dirty_limits() tries to resolve the proportion: bdi_bg_thresh : bdi_thresh = background_thresh : dirty_thresh by dividing by zero. Signed-off-by: Maxim Patlasov --- mm/page-writeback.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 518e2c3..e0c9430 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1306,9 +1306,9 @@ static inline void bdi_dirty_limits(struct backing_dev_info *bdi, *bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); if (bdi_bg_thresh) - *bdi_bg_thresh = div_u64((u64)*bdi_thresh * - background_thresh, - dirty_thresh); + *bdi_bg_thresh = dirty_thresh ? div_u64((u64)*bdi_thresh * + background_thresh, + dirty_thresh) : 0; /* * In order to avoid the stacked BDI deadlock we need -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/