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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 45500C282C4 for ; Mon, 4 Feb 2019 17:51:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0F5312080A for ; Mon, 4 Feb 2019 17:51:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="A7FU0101" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728111AbfBDRvQ (ORCPT ); Mon, 4 Feb 2019 12:51:16 -0500 Received: from mail-pl1-f193.google.com ([209.85.214.193]:45244 "EHLO mail-pl1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728020AbfBDRvQ (ORCPT ); Mon, 4 Feb 2019 12:51:16 -0500 Received: by mail-pl1-f193.google.com with SMTP id a14so246303plm.12 for ; Mon, 04 Feb 2019 09:51:15 -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:user-agent; bh=gxZcmyrTQ7o98rYEkVwMPBb43wOs0dpxU//wAZw+xbw=; b=A7FU0101Au69fdbvimqEQXAxTxm4eQHcMqr/DHY+0Xd35XfeXkYU3X3Dj0t4aPpV2+ rx31+wKEKVo0388YnAAFzU36OpBWu2TfXTwzoMF8wlup8kGSsehMHugVJ/bW1pb2SpAD G6J85D8wIIdCalmI7cGyRIsRg/L1uCRkAznDmHsXMHwiaveQq8PC5xE2W5+ZrzpaIcQ+ W1S32XGZJuuP/+zEuY4rAvZgR8yo3NDxaRMloUtG9zyws78xLr/NPZQvJth5pXJiG6s3 zHOChaldNMZHgmeF10T17McWCH5NTWmx81B3Q7dDTUsugo+xUB5BCkNM3iqhgMUhBsoM CTPw== 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:user-agent; bh=gxZcmyrTQ7o98rYEkVwMPBb43wOs0dpxU//wAZw+xbw=; b=j/LBTra40tkTXw5prgiq3K6wRDiBA4jV96iJzIr9rUwHAj4CdfU390Fj8bfLUZWM4N hFm3S603qVQtExMy9287aRHvU1QDrZAgIhEU9Na5qTxgB8D9JAxsNVn2MC4fd5BsZA1r qaCQRivqBAgvqMS3qa2Xlk+Viy7higW8jcfqaQrOmQlicbLNpAFVYI7XQAjbUn1Wz17I KGTCk75KvFGOLzT64dBOYv/sMX5bXRPOA2QDmnFArrWLE3PYrHL2cs1OV52OuW83/rsL jpG4+qtRQPkc36G9UR/AQixU8MPqDx5qDCOPfP8LJ5GPCNwmt/uR0ppfSmQWumAMq8Ff r8XQ== X-Gm-Message-State: AHQUAuaNbRpRmFdcPZPJAggtFkpj1peaXwJtgWUeQWGGSKwhVZlWwqI5 8S4kGiaGLF3m9fRlIQQaKbybnw== X-Google-Smtp-Source: AHgI3IYqNbWmq8UYZLwTkZ1W2v6TF+N3keX9gC9JaVu9p6Jyvue8K0UtB8kV2A8jzdpNeHMjlFO+qg== X-Received: by 2002:a17:902:2c83:: with SMTP id n3mr609436plb.104.1549302675060; Mon, 04 Feb 2019 09:51:15 -0800 (PST) Received: from ziepe.ca (S010614cc2056d97f.ed.shawcable.net. [174.3.196.123]) by smtp.gmail.com with ESMTPSA id 6sm1139978pfv.30.2019.02.04.09.51.11 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 04 Feb 2019 09:51:11 -0800 (PST) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1gqiOk-0003oc-Or; Mon, 04 Feb 2019 10:51:10 -0700 Date: Mon, 4 Feb 2019 10:51:10 -0700 From: Jason Gunthorpe To: Christopher Lameter Cc: john.hubbard@gmail.com, Andrew Morton , linux-mm@kvack.org, Al Viro , Christian Benvenuti , Christoph Hellwig , Dan Williams , Dave Chinner , Dennis Dalessandro , Doug Ledford , Jan Kara , Jerome Glisse , Matthew Wilcox , Michal Hocko , Mike Rapoport , Mike Marciniszyn , Ralph Campbell , Tom Talpey , LKML , linux-fsdevel@vger.kernel.org, John Hubbard Subject: Re: [PATCH 0/6] RFC v2: mm: gup/dma tracking Message-ID: <20190204175110.GA10237@ziepe.ca> References: <20190204052135.25784-1-jhubbard@nvidia.com> <01000168b980e880-a7d8e0db-84fb-4398-8269-149c66b701b4-000000@email.amazonses.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <01000168b980e880-a7d8e0db-84fb-4398-8269-149c66b701b4-000000@email.amazonses.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Feb 04, 2019 at 05:14:19PM +0000, Christopher Lameter wrote: > Frankly I still think this does not solve anything. > > Concurrent write access from two sources to a single page is simply wrong. > You cannot make this right by allowing long term RDMA pins in a filesystem > and thus the filesystem can never update part of its files on disk. Fundamentally this patch series is fixing O_DIRECT to not crash the kernel in extreme cases.. RDMA has the same problem, but it is much easier to hit. I think questions related to RDMA are somewhat separate, and maybe it should be blocked, or not, but either way O_DIRECT has to be fixed. Jason