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=-12.9 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1, USER_IN_DEF_DKIM_WL 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 482F6C2BB84 for ; Thu, 17 Sep 2020 02:13:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 08B8E2072E for ; Thu, 17 Sep 2020 02:13:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="SxAIwAWl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726148AbgIQCNC (ORCPT ); Wed, 16 Sep 2020 22:13:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57584 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726115AbgIQCNA (ORCPT ); Wed, 16 Sep 2020 22:13:00 -0400 Received: from mail-oo1-xc44.google.com (mail-oo1-xc44.google.com [IPv6:2607:f8b0:4864:20::c44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B5F3EC061788 for ; Wed, 16 Sep 2020 19:05:16 -0700 (PDT) Received: by mail-oo1-xc44.google.com with SMTP id z1so191800ooj.3 for ; Wed, 16 Sep 2020 19:05:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:in-reply-to:message-id:references :user-agent:mime-version; bh=FvBdfI3/8JYEzHDwTJchNGznx9TCTfOWN6nMTk+cWRg=; b=SxAIwAWl1MqxQGVya1/LLGYLyQUf80qPgV3UgTzda0zs4xtGvK+4t42qChTNnUsQp2 iidBl3RcjWjxLEf3TZErhnJNVVQbN7kfMfUmVvIATlXjukaBN+biw4DGFEtwxso0eFH3 U57Zvvxg6m/kE5XelTs1/4GU+7H9JXM071r8m/4ZtDTvnHENVfGtnySAZv4kOHTr0OEO nGgEa2imdIkbWGjE4w2eJKI3i7opSAcSjM4lAf/eWxB03Q2LwB/TXuLJwne9YkNYXg0u /h/dWj2zkQOOZ9HHYhSHhoHJtjkFEXp5gat/GmMoyC4Tw0RZhLUvTdQyQRkgrx/gGf3i dp5A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version; bh=FvBdfI3/8JYEzHDwTJchNGznx9TCTfOWN6nMTk+cWRg=; b=sRvGOCVgAA6Tqx4FP68e/D6EB8qFOH9MrwX/XhhYHHxJ/yIeyeRefNlt5WoT0UrTh/ Lfq2LBOWgBF308hO8Yy9ZydKDPUgMNaYC0YSmt+LDUd4e4wlN82PneLyGnCNj2rBZsQO CNYspjh9Jzj1+xymGtWGRLTCbpm7VroFz5Y7ldIafE8bHG1CPOwXiokeW4SV9lPUcyPQ hEWVnKSGUsjomCt+gqylTR2PSIn6GteGJsBXifmOmd+himFW3dBT26lTGd1ZvRiKsiV9 j17EvW1VjALTl2SiJFqpaNx4oflBMsMT+f0rdrH5U34ovI1TlkN+6kK4yKn2qKVplpVE cChQ== X-Gm-Message-State: AOAM533A+Ri3O3n/VhWNr7kw5mCzACBHwHBNMC/LRyWi1N4gExUZPh2X LvMLjcADM5xFBDs2ZoMR5bo9mg== X-Google-Smtp-Source: ABdhPJwlHAL814Qbgr+EScHD+loUynWF6I3FcBxRyuexwIjAE/FXXv9TKSXjo79ezbsysUHb+aAFHw== X-Received: by 2002:a4a:c541:: with SMTP id j1mr19671594ooq.13.1600308314725; Wed, 16 Sep 2020 19:05:14 -0700 (PDT) Received: from eggly.attlocal.net (172-10-233-147.lightspeed.sntcca.sbcglobal.net. [172.10.233.147]) by smtp.gmail.com with ESMTPSA id a4sm8527275oif.3.2020.09.16.19.05.09 (version=TLS1 cipher=ECDHE-ECDSA-AES128-SHA bits=128/128); Wed, 16 Sep 2020 19:05:11 -0700 (PDT) Date: Wed, 16 Sep 2020 19:04:46 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: Dave Chinner cc: Jan Kara , Amir Goldstein , Andreas Gruenbacher , Theodore Tso , Martin Brandenburg , Mike Marshall , Damien Le Moal , Jaegeuk Kim , Qiuyang Sun , linux-xfs , linux-fsdevel , Linux MM , linux-kernel , Matthew Wilcox , Linus Torvalds , "Kirill A. Shutemov" , Andrew Morton , Al Viro , nborisov@suse.de Subject: Re: More filesystem need this fix (xfs: use MMAPLOCK around filemap_map_pages()) In-Reply-To: <20200917014454.GZ12131@dread.disaster.area> Message-ID: References: <20200623052059.1893966-1-david@fromorbit.com> <20200916155851.GA1572@quack2.suse.cz> <20200917014454.GZ12131@dread.disaster.area> User-Agent: Alpine 2.11 (LSU 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Thu, 17 Sep 2020, Dave Chinner wrote: > > So.... > > P0 p1 > > hole punch starts > takes XFS_MMAPLOCK_EXCL > truncate_pagecache_range() > unmap_mapping_range(start, end) > > > do_fault_around() > ->map_pages > filemap_map_pages() > page mapping valid, > page is up to date > maps PTEs > > truncate_inode_pages_range() > truncate_cleanup_page(page) > invalidates page > delete_from_page_cache_batch(page) > frees page > No. filemap_map_pages() checks page->mapping after trylock_page(), before setting up the pte; and truncate_cleanup_page() does a one-page unmap_mapping_range() if page_mapped(), while holding page lock. (Of course, there's a different thread, in which less reliance on page lock is being discussed, but that would be a future thing.) Hugh