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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=no 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 249BFC33CA9 for ; Tue, 14 Jan 2020 00:29:29 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DB39E207FF for ; Tue, 14 Jan 2020 00:29:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="AkUnUnnb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DB39E207FF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8BC3B8E000D; Mon, 13 Jan 2020 19:29:28 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 86F808E0003; Mon, 13 Jan 2020 19:29:28 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6E98D8E000D; Mon, 13 Jan 2020 19:29:28 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0179.hostedemail.com [216.40.44.179]) by kanga.kvack.org (Postfix) with ESMTP id 51DAC8E0003 for ; Mon, 13 Jan 2020 19:29:28 -0500 (EST) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id F22A0181AC9CB for ; Tue, 14 Jan 2020 00:29:27 +0000 (UTC) X-FDA: 76374355974.15.bomb89_6fb79f582c715 X-HE-Tag: bomb89_6fb79f582c715 X-Filterd-Recvd-Size: 3007 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf45.hostedemail.com (Postfix) with ESMTP for ; Tue, 14 Jan 2020 00:29:27 +0000 (UTC) Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BAF82217BA; Tue, 14 Jan 2020 00:29:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578961767; bh=mLyrft3aSb+s2k9W40SWOUicySea9eDPr2t0wOeHrIg=; h=Date:From:To:Subject:In-Reply-To:From; b=AkUnUnnbQsDjOwF0uPgfLJ9XIe3UmKnTBkH0AV5Z3rDbbG6GPigUGEl1egu3/QK/D MSJqtiXccdQNqlmRQlT767gu2uLQa3ZAul0WX+EKFZo9VIHaB9GkUEmGA+mdvmErYX Jq13vFGApLHmqG7EqDkYNOa3Tw+ciV/MufFYeFAY= Date: Mon, 13 Jan 2020 16:29:26 -0800 From: Andrew Morton To: tj@kernel.org, cai@lca.pw, axboe@kernel.dk, wenyang@linux.alibaba.com, akpm@linux-foundation.org, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 08/11] mm/page-writeback.c: use div64_ul() for u64-by-unsigned-long divide Message-ID: <20200114002926.Cskkh%akpm@linux-foundation.org> In-Reply-To: <20200113162831.f7d69e11e9e673c40005c9b0@linux-foundation.org> User-Agent: s-nail v14.9.15 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: From: Wen Yang Subject: mm/page-writeback.c: use div64_ul() for u64-by-unsigned-long divide The two variables 'numerator' and 'denominator', though they are declared as long, they should actually be unsigned long (according to the implementation of the fprop_fraction_percpu() function) And do_div() does a 64-by-32 division, while the divisor 'denominator' is unsigned long, thus 64-bit on 64-bit platforms. Hence the proper function to call is div64_ul(). Link: http://lkml.kernel.org/r/20200102081442.8273-3-wenyang@linux.alibaba.com Signed-off-by: Wen Yang Reviewed-by: Andrew Morton Cc: Qian Cai Cc: Tejun Heo Cc: Jens Axboe Signed-off-by: Andrew Morton --- mm/page-writeback.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/mm/page-writeback.c~mm-page-writebackc-use-div64_ul-for-u64-by-unsigned-long-divide +++ a/mm/page-writeback.c @@ -766,7 +766,7 @@ static unsigned long __wb_calc_thresh(st struct wb_domain *dom = dtc_dom(dtc); unsigned long thresh = dtc->thresh; u64 wb_thresh; - long numerator, denominator; + unsigned long numerator, denominator; unsigned long wb_min_ratio, wb_max_ratio; /* @@ -777,7 +777,7 @@ static unsigned long __wb_calc_thresh(st wb_thresh = (thresh * (100 - bdi_min_ratio)) / 100; wb_thresh *= numerator; - do_div(wb_thresh, denominator); + wb_thresh = div64_ul(wb_thresh, denominator); wb_min_max_ratio(dtc->wb, &wb_min_ratio, &wb_max_ratio); _