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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,UNPARSEABLE_RELAY 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 42F7EC4321D for ; Wed, 22 Aug 2018 19:20:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E50962098B for ; Wed, 22 Aug 2018 19:20:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E50962098B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728131AbeHVWrA (ORCPT ); Wed, 22 Aug 2018 18:47:00 -0400 Received: from out30-131.freemail.mail.aliyun.com ([115.124.30.131]:38584 "EHLO out30-131.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728051AbeHVWrA (ORCPT ); Wed, 22 Aug 2018 18:47:00 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R371e4;CH=green;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01f04455;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=14;SR=0;TI=SMTPD_---0T734itb_1534965638; Received: from US-143344MP.local(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0T734itb_1534965638) by smtp.aliyun-inc.com(127.0.0.1); Thu, 23 Aug 2018 03:20:43 +0800 Subject: Re: [RFC v8 PATCH 3/5] mm: mmap: zap pages with read mmap_sem in munmap To: Vlastimil Babka , mhocko@kernel.org, willy@infradead.org, ldufour@linux.vnet.ibm.com, kirill@shutemov.name, akpm@linux-foundation.org, peterz@infradead.org, mingo@redhat.com, acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1534358990-85530-1-git-send-email-yang.shi@linux.alibaba.com> <1534358990-85530-4-git-send-email-yang.shi@linux.alibaba.com> <7145895b-ef56-f5ee-d139-609819d9a107@suse.cz> From: Yang Shi Message-ID: <2f447d4e-9e16-8030-85f0-4e258a7eafa3@linux.alibaba.com> Date: Wed, 22 Aug 2018 12:20:37 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <7145895b-ef56-f5ee-d139-609819d9a107@suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/22/18 4:11 AM, Vlastimil Babka wrote: > On 08/15/2018 08:49 PM, Yang Shi wrote: > >> + start_vma = munmap_lookup_vma(mm, start, end); >> + if (!start_vma) >> + goto out; >> + if (IS_ERR(start_vma)) { >> + ret = PTR_ERR(start_vma); >> + goto out; >> + } >> + >> + prev = start_vma->vm_prev; >> + >> + if (unlikely(uf)) { >> + ret = userfaultfd_unmap_prep(start_vma, start, end, uf); >> + if (ret) >> + goto out; >> + } >> + > You sure it's ok to redo this in case of goto regular path? The > preparations have some side-effects... I would rather move this after > the regular path check? This preparation sets vma->vm_userfaultfd_ctx.ctx for each vmas. But, before doing this, it calls has_unmap_ctx() to check if the ctx has been set or not. If it has been set, it just skip the vma. It sounds ok, right?