From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1816CC2D0DD for ; Thu, 2 Jan 2020 08:15:23 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D707621734 for ; Thu, 2 Jan 2020 08:15:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D707621734 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6E1608E0006; Thu, 2 Jan 2020 03:15:22 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 6B8358E0003; Thu, 2 Jan 2020 03:15:22 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5F5968E0006; Thu, 2 Jan 2020 03:15:22 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0245.hostedemail.com [216.40.44.245]) by kanga.kvack.org (Postfix) with ESMTP id 45CD48E0003 for ; Thu, 2 Jan 2020 03:15:22 -0500 (EST) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id AC3E9181AC9BF for ; Thu, 2 Jan 2020 08:15:21 +0000 (UTC) X-FDA: 76331984442.25.brush13_860145ab29a18 X-HE-Tag: brush13_860145ab29a18 X-Filterd-Recvd-Size: 2435 Received: from out30-45.freemail.mail.aliyun.com (out30-45.freemail.mail.aliyun.com [115.124.30.45]) by imf11.hostedemail.com (Postfix) with ESMTP for ; Thu, 2 Jan 2020 08:15:20 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=wenyang@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0TmanhCh_1577952902; Received: from localhost(mailfrom:wenyang@linux.alibaba.com fp:SMTPD_---0TmanhCh_1577952902) by smtp.aliyun-inc.com(127.0.0.1); Thu, 02 Jan 2020 16:15:14 +0800 From: Wen Yang To: Andrew Morton , Qian Cai Cc: xlpang@linux.alibaba.com, Wen Yang , Tejun Heo , Jens Axboe , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/3] mm/page-writeback.c: avoid potential division by zero in wb_min_max_ratio() Date: Thu, 2 Jan 2020 16:14:40 +0800 Message-Id: <20200102081442.8273-2-wenyang@linux.alibaba.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20200102081442.8273-1-wenyang@linux.alibaba.com> References: <20200102081442.8273-1-wenyang@linux.alibaba.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The variables 'min' and 'max' are unsigned long and do_div truncates them to 32 bits, which means it can test non-zero and be truncated to zero for division. Fix this issue by using div64_ul() instead. Fixes: 693108a8a667 ("writeback: make bdi->min/max_ratio handling cgroup = writeback aware") Signed-off-by: Wen Yang Cc: Andrew Morton Cc: Qian Cai Cc: Tejun Heo Cc: Jens Axboe Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/page-writeback.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 50055d2..2d658b2 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -201,11 +201,11 @@ static void wb_min_max_ratio(struct bdi_writeback *= wb, if (this_bw < tot_bw) { if (min) { min *=3D this_bw; - do_div(min, tot_bw); + min =3D div64_ul(min, tot_bw); } if (max < 100) { max *=3D this_bw; - do_div(max, tot_bw); + max =3D div64_ul(max, tot_bw); } } =20 --=20 1.8.3.1