Received: by 2002:a05:6a10:6744:0:0:0:0 with SMTP id w4csp1189568pxu; Fri, 16 Oct 2020 06:14:04 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyNWWWZbQ9g+MJkt64a0oTwOjTX7KVrTn2tU7eT/RZUBu1eVBrSJ1f7SFQy8TzB6bwEgUmT X-Received: by 2002:a17:906:d978:: with SMTP id rp24mr3863601ejb.0.1602854044192; Fri, 16 Oct 2020 06:14:04 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1602854044; cv=none; d=google.com; s=arc-20160816; b=cT/T1ufR2Cc027KU6ZYQFy//TA+yciOmGL84oUISDKXSmTajAjsn8o7Bh4Eka6PJH7 natxtXc0cw3qdkTNJ672J7n6DM/Q7hAAxkNTPymI1BPxglmyv6LY1vb8+tiwBDlIdKUf HxHriOGAyQQXyOYHCi75x9rhDn/SCSoF9ww8ZziialnsCppRkKZCY7eAuACs36ZvZ78u rBZ8qqtxaaYQBuEh5Lk5ncUGHAwvqGAe/QREqv8Q0ZhcvRqxKjyLrnzdHJS2/CXHuWO9 W40iPXKrxN+Wx45u3+BXX/Jhme8rn7RTr4XsIoBH5ua45TPoyfj1jXFayEz+Bi/Z3qOP vdxA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:message-id:user-agent:references:in-reply-to :subject:cc:to:from:date:content-transfer-encoding:mime-version; bh=n10WugERM1W0m9WK9zlmp50bw0DCO9zfHR69Bfs1+lA=; b=aJmcI2kRN/wlp4Hl00XDZ0Q8SDfFgEM67RG/Jxc8CL6I9Su9Ni8e1UtEDerHuOvjUL XjZQN2YKG+p9jbyVp1dswRlQ6yHXvAFa5oMulnde2xPOXCGub/l4gdpVoJuHj5RoyWPB R3gYHju9AKDvX7gxEk2O1e37sLuqPu2dmFuyiibHTMBfiZUp5I4o8p/5oV/VdOPzo6jo gu6ZpNgHlc3JDTJuyOxrO/Nar7L1XAGldtJmr2Lck6piTdfQTPFKBLjuxxCzk2ICd2zR PoJ7+1NsWP73VqChxCzkRKHjCslp/wfhwkKJzjBS7ghBjqBV+XFk4oQOodswVPCZVtU2 buAQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id t7si1675944ejr.659.2020.10.16.06.13.38; Fri, 16 Oct 2020 06:14:04 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407566AbgJPMhK (ORCPT + 99 others); Fri, 16 Oct 2020 08:37:10 -0400 Received: from mx2.suse.de ([195.135.220.15]:37288 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2407562AbgJPMhJ (ORCPT ); Fri, 16 Oct 2020 08:37:09 -0400 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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