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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 AD4C7C43381 for ; Sat, 2 Mar 2019 18:52:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 678C420830 for ; Sat, 2 Mar 2019 18:52:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726994AbfCBSwS (ORCPT ); Sat, 2 Mar 2019 13:52:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:36574 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726648AbfCBSwR (ORCPT ); Sat, 2 Mar 2019 13:52:17 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9C5D4307CEB2; Sat, 2 Mar 2019 18:51:47 +0000 (UTC) Received: from sky.random (ovpn-121-1.rdu2.redhat.com [10.10.121.1]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 220315D70A; Sat, 2 Mar 2019 18:51:45 +0000 (UTC) Date: Sat, 2 Mar 2019 13:51:44 -0500 From: Andrea Arcangeli To: Jan Stancek Cc: linux-mm@kvack.org, akpm@linux-foundation.org, willy@infradead.org, peterz@infradead.org, riel@surriel.com, mhocko@suse.com, ying.huang@intel.com, jrdr.linux@gmail.com, jglisse@redhat.com, aneesh.kumar@linux.ibm.com, david@redhat.com, raquini@redhat.com, rientjes@google.com, kirill@shutemov.name, mgorman@techsingularity.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm/memory.c: do_fault: avoid usage of stale vm_area_struct Message-ID: <20190302185144.GD31083@redhat.com> References: <20190302171043.GP11592@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Sat, 02 Mar 2019 18:51:47 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Jan, On Sat, Mar 02, 2019 at 07:19:39PM +0100, Jan Stancek wrote: > + struct mm_struct *vm_mm = READ_ONCE(vma->vm_mm); The vma->vm_mm cannot change under gcc there, so no need of READ_ONCE. The release of mmap_sem has release semantics so the vma->vm_mm access cannot be reordered after up_read(mmap_sem) either. Other than the above detail: Reviewed-by: Andrea Arcangeli Thanks, Andrea