From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932780AbaHHUwf (ORCPT ); Fri, 8 Aug 2014 16:52:35 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:41156 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932716AbaHHUwb (ORCPT ); Fri, 8 Aug 2014 16:52:31 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Maxim Patlasov , Michal Hocko , KOSAKI Motohiro , Wu Fengguang , Johannes Weiner , Andrew Morton , Linus Torvalds , Kamal Mostafa Subject: [PATCH 3.13 193/259] mm/page-writeback.c: fix divide by zero in bdi_dirty_limits() Date: Fri, 8 Aug 2014 13:40:16 -0700 Message-Id: <1407530482-4483-194-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1407530482-4483-1-git-send-email-kamal@canonical.com> References: <1407530482-4483-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11.6 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Maxim Patlasov commit f6789593d5cea42a4ecb1cbeab6a23ade5ebbba7 upstream. 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 Acked-by: Rik van Riel Cc: Michal Hocko Cc: KOSAKI Motohiro Cc: Wu Fengguang Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Kamal Mostafa --- 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 d013dba..9f45f87 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1324,9 +1324,9 @@ 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 -- 1.9.1