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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 4AD15C433DB for ; Fri, 15 Jan 2021 18:41:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D10523A5A for ; Fri, 15 Jan 2021 18:41:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387584AbhAOSkt (ORCPT ); Fri, 15 Jan 2021 13:40:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33966 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732398AbhAOSkt (ORCPT ); Fri, 15 Jan 2021 13:40:49 -0500 Received: from mail-qt1-x82d.google.com (mail-qt1-x82d.google.com [IPv6:2607:f8b0:4864:20::82d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2718CC0613D3 for ; Fri, 15 Jan 2021 10:40:09 -0800 (PST) Received: by mail-qt1-x82d.google.com with SMTP id j26so6725358qtq.8 for ; Fri, 15 Jan 2021 10:40:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=7iqMaLM5ngsObMfPwH4GTR7fbydas+V1RNx2qyihbRE=; b=OhxHt8mmLJBsBMtZBFbnzLbxdAsOB8Ka3zQhmpOBvqIxz1zjBrp/a47AIXhKA0t3km YlHhKjdWMqC7jNahlHbUlRUPmkRb6aO3yRCF+8ADRWKYCO7qd059e5vvQyc9p7FxMpRy yK6aElGVEG1rRRoH4i0ELby/mv6XobYfm7NJGIKaJEA8DWYgI7JeHVHHJ5l69RwW2WVM MNIBWcLwwew5ASqQAc7q4SYDX9xA6MsERsWIb//cqdNkvQpmcUggFcLkB3zoFQMDBzw9 T/XsBb0QSqYdbXf3XNPHdZZtNVQ/dL8ZHqC6DmEFhEVb5SB5csXt7sqriqrmopJy8BxM omLA== 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:message-id:references :mime-version:content-disposition:in-reply-to; bh=7iqMaLM5ngsObMfPwH4GTR7fbydas+V1RNx2qyihbRE=; b=EXoik4K8zs7cZx9sg+KDJdNGTPHeS89yJoZ1fLLiistSUXcUqy4Ec86+ETvYPHImPl HmiP66U1i7BwPH0PfpQAZDWEldN8IzjSd+NKiVOOBMWHzAoLAJYCq1DTj71Nx9QWizn0 Qi8Jr234SJvbn/qy3nj5pLLjQaJ5nqQZ/WxmM9GE5yAbYm3RL+R8PmXnymr8SifHRPRK 3sBlfJlh3XRZzRAkZCS++OMrbT9cliDnUA2wrodRnGLku6ZJiycY3wwyOuJOjWUQwnb1 VHb3FtC3BbHsVrMDvmlaHeei+0iEDQ40GmMZnLXTFvfFs01UnEzJQW3gcy3c6u7NqpjO mY1Q== X-Gm-Message-State: AOAM5314FpBQu6mOl4bBMqoFn1lQmiaMcHeB/IJJCaJZz6ybazv9hNP5 74MYXq941Qg9NZjm1jHosOVU/A== X-Google-Smtp-Source: ABdhPJwYvWXIvOLXd5qgmW2cmliLgAWyRNvV6PcZolMroOO0r5/CLLBELstEgOcEHd1noGRZeNtm8w== X-Received: by 2002:a05:622a:4d1:: with SMTP id q17mr7113455qtx.272.1610736008331; Fri, 15 Jan 2021 10:40:08 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-142-162-115-133.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.115.133]) by smtp.gmail.com with ESMTPSA id u10sm1059825qtb.24.2021.01.15.10.40.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 Jan 2021 10:40:07 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1l0U10-001hs5-Uq; Fri, 15 Jan 2021 14:40:06 -0400 Date: Fri, 15 Jan 2021 14:40:06 -0400 From: Jason Gunthorpe To: Pavel Tatashin Cc: LKML , linux-mm , Andrew Morton , Vlastimil Babka , Michal Hocko , David Hildenbrand , Oscar Salvador , Dan Williams , Sasha Levin , Tyler Hicks , Joonsoo Kim , mike.kravetz@oracle.com, Steven Rostedt , Ingo Molnar , Peter Zijlstra , Mel Gorman , Matthew Wilcox , David Rientjes , John Hubbard , Linux Doc Mailing List , Ira Weiny , linux-kselftest@vger.kernel.org Subject: Re: [PATCH v4 08/10] mm/gup: limit number of gup migration failures, honor failures Message-ID: <20210115184006.GH4605@ziepe.ca> References: <20201217185243.3288048-1-pasha.tatashin@soleen.com> <20201217185243.3288048-9-pasha.tatashin@soleen.com> <20201217205048.GL5487@ziepe.ca> <20201218141927.GM5487@ziepe.ca> <20210113195528.GD4605@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Fri, Jan 15, 2021 at 01:10:27PM -0500, Pavel Tatashin wrote: > I've been thinking about this some more. Again, I am not sure this is > a bug. I understand split_huge_pmd() may split the PMD size page into > PTEs and leave the compound page intact. However, in order for pages[] > to have non sequential addresses in compound page, those PTEs must > also be migrated after split_huge_pmd(), Why focus on migrated? Anything could happen to those PTEs: they could be COW'd, they could be mmap/munmap'd, etc. Jason