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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED 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 B375CC65C22 for ; Fri, 2 Nov 2018 16:05:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 653C620657 for ; Fri, 2 Nov 2018 16:05:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="SvW0RgOQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 653C620657 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org 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 S1727726AbeKCBNP (ORCPT ); Fri, 2 Nov 2018 21:13:15 -0400 Received: from mail-lf1-f68.google.com ([209.85.167.68]:45056 "EHLO mail-lf1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727551AbeKCBNO (ORCPT ); Fri, 2 Nov 2018 21:13:14 -0400 Received: by mail-lf1-f68.google.com with SMTP id b20so1661220lfa.12 for ; Fri, 02 Nov 2018 09:05:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=nCwZs6Bfos9PO44MFQbBS84Lh4BmDzogIsp8qZX3l+M=; b=SvW0RgOQfy2S4QDyxf+xamrG+27zN1HOhUY7yQxeGlzhwvHzguH1KxCiJpRJFdS9vq PSEjdtO+CXUN0BXZowRh7iSLUvf/zbsBJq8i2Hpc+JMA943EDqqVWLB12IIaqkQPYchH 78Cq4SS+Sa4ttXz83lq7CYhBP//xA8fFyz4wg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=nCwZs6Bfos9PO44MFQbBS84Lh4BmDzogIsp8qZX3l+M=; b=Y1sZW+OhwkT/9IEew4g4lAeFHRjgYBMdkFqC8dQWEXAoMN/rarfcJUdWYqNLzQRMNd PvR6Wq1SVEBqpuSewwFf2QfG6PInsgJUJPOjcvYanMKCMhYICiszi9Y/jLD7Vy+nLLxZ Fz+lqbSk1ID/TAPysd7xxdGc4lUbiQ8P2F/060avtMl7+r/4Y1NBMjyk8NGfnET31DfW k612HQ3yN+2HhCzb2aDAVua7XW3WRHKoglGIHDUQ4elj+ddewCQmaJzfXoK6TzOmjyGf E69aesprP09n8c9NkOySvdximjvZ2W+pZVk0Tml3Hs9xY5JDi08/sfcbEuUMTFD5R1xa mHTg== X-Gm-Message-State: AGRZ1gJhE3pd+4q6Nemtac9tXK8a5/3tXT4411SjkAbfrKFbZ+4Wp9Is 2tgjux4nCxY7U681VR6nE8THdLc/ZhkfSg== X-Google-Smtp-Source: AJdET5eAarjnr41MUZ81fW6MGosvQ4kQ6X4L2QS92sJx+Ciz84EaYFhP+xxgXC5vq62c5iZsd8ndbg== X-Received: by 2002:a19:c18d:: with SMTP id r135mr6624259lff.59.1541174737566; Fri, 02 Nov 2018 09:05:37 -0700 (PDT) Received: from mail-lj1-f179.google.com (mail-lj1-f179.google.com. [209.85.208.179]) by smtp.gmail.com with ESMTPSA id u26-v6sm1495853lji.85.2018.11.02.09.05.33 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 02 Nov 2018 09:05:34 -0700 (PDT) Received: by mail-lj1-f179.google.com with SMTP id t22-v6so2199640lji.7 for ; Fri, 02 Nov 2018 09:05:33 -0700 (PDT) X-Received: by 2002:a2e:874e:: with SMTP id q14-v6mr5432299ljj.120.1541174733203; Fri, 02 Nov 2018 09:05:33 -0700 (PDT) MIME-Version: 1.0 References: <1541164962-28533-1-git-send-email-will.deacon@arm.com> <20181102145638.gehn7eszv22lelh6@kshutemo-mobl1> <20181102152516.dkqpeubxh6c3phl2@kshutemo-mobl1> In-Reply-To: <20181102152516.dkqpeubxh6c3phl2@kshutemo-mobl1> From: Linus Torvalds Date: Fri, 2 Nov 2018 09:05:17 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] mremap: properly flush TLB before releasing the page To: kirill@shutemov.name Cc: Jann Horn , will.deacon@arm.com, Greg KH , stable@vger.kernel.org, Linux Kernel Mailing List , Ingo Molnar , Peter Zijlstra , linux-mm@kvack.org, mhocko@kernel.org, hughd@google.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 2, 2018 at 8:25 AM Kirill A. Shutemov wrote: > > I wounder if it would be cheaper to fix this by taking i_mmap_lock_write() > unconditionally in mremap() path rather than do a lot of flushing. That wouldn't help. Think anonymous pages and try_to_free() rmap walk. So then I think we'd have to take the anonvma lock or something. And it's not like we are likely to even do any more flushes, really. We don't flush for each page, only for each page table. So every 512 pages or so. Linus