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=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 444ECC433E7 for ; Fri, 16 Oct 2020 12:37:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B0C45221EB for ; Fri, 16 Oct 2020 12:37:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B0C45221EB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9B2DB940007; Fri, 16 Oct 2020 08:37:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 960D9900002; Fri, 16 Oct 2020 08:37:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 875FA940007; Fri, 16 Oct 2020 08:37:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0066.hostedemail.com [216.40.44.66]) by kanga.kvack.org (Postfix) with ESMTP id 6D6B9900002 for ; Fri, 16 Oct 2020 08:37:10 -0400 (EDT) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 2A3BF181AEF15 for ; Fri, 16 Oct 2020 12:37:10 +0000 (UTC) X-FDA: 77377738620.09.smile79_150e4192721d Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin09.hostedemail.com (Postfix) with ESMTP id 0C6EC180AD806 for ; Fri, 16 Oct 2020 12:37:10 +0000 (UTC) X-HE-Tag: smile79_150e4192721d X-Filterd-Recvd-Size: 1508 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf35.hostedemail.com (Postfix) with ESMTP for ; Fri, 16 Oct 2020 12:37:09 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 679EAAC1F; Fri, 16 Oct 2020 12:37:08 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Fri, 16 Oct 2020 14:37:08 +0200 From: osalvador@suse.de To: Michal Hocko Cc: Shijie Luo , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linmiaohe@huawei.com, linfeilong@huawei.com Subject: Re: [PATCH] mm: fix potential pte_unmap_unlock pte error In-Reply-To: <20201016123137.GH22589@dhcp22.suse.cz> References: <20201015121534.50910-1-luoshijie1@huawei.com> <20201016123137.GH22589@dhcp22.suse.cz> User-Agent: Roundcube Webmail Message-ID: X-Sender: osalvador@suse.de 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: On 2020-10-16 14:31, Michal Hocko wrote: > I do not like the fix though. The code is really confusing. Why should > we check for flags in each iteration of the loop when it cannot change? > Also why should we take the ptl lock in the first place when the look > is > broken out immediately? About checking the flags: https://lore.kernel.org/linux-mm/20190320081643.3c4m5tec5vx653sn@d104.suse.de/#t