From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754322AbaHESOI (ORCPT ); Tue, 5 Aug 2014 14:14:08 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:52111 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754154AbaHESOB (ORCPT ); Tue, 5 Aug 2014 14:14:01 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Maxim Patlasov , Rik van Riel , Michal Hocko , KOSAKI Motohiro , Wu Fengguang , Johannes Weiner , Andrew Morton , Linus Torvalds Subject: [PATCH 3.15 13/42] mm/page-writeback.c: fix divide by zero in bdi_dirty_limits() Date: Tue, 5 Aug 2014 11:13:27 -0700 Message-Id: <20140805181321.422447558@linuxfoundation.org> X-Mailer: git-send-email 2.0.4 In-Reply-To: <20140805181321.018370988@linuxfoundation.org> References: <20140805181321.018370988@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.15-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: Greg Kroah-Hartman --- mm/page-writeback.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1324,9 +1324,9 @@ static inline void bdi_dirty_limits(stru *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