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[54.240.9.54]) by mx.google.com with ESMTPS id z65si1652677qtc.247.2019.02.04.10.21.39 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 04 Feb 2019 10:21:39 -0800 (PST) Received-SPF: pass (google.com: domain of 01000168b9be8b5a-3b4f8036-50c8-4180-b39f-9ef28cb60cce-000000@amazonses.com designates 54.240.9.54 as permitted sender) client-ip=54.240.9.54; Authentication-Results: mx.google.com; dkim=pass header.i=@amazonses.com header.s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug header.b=eqqPaLK7; spf=pass (google.com: domain of 01000168b9be8b5a-3b4f8036-50c8-4180-b39f-9ef28cb60cce-000000@amazonses.com designates 54.240.9.54 as permitted sender) smtp.mailfrom=01000168b9be8b5a-3b4f8036-50c8-4180-b39f-9ef28cb60cce-000000@amazonses.com DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug; d=amazonses.com; t=1549304499; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References:MIME-Version:Content-Type:Feedback-ID; bh=nirpWIDcnC5D/gqeHhqZEfTAwTpOapalA6vQSFEJlrg=; b=eqqPaLK753ERyVHOui9AhXNyEHkliLZNsy0bLhnJAXqdnvCX6SuwvNdVR6Ayg24Q BMtaV4Me15la7/pns5BOfhHu4OT8QcohddOIF2e3YaiR8izR0bS9HIiZjS5MZ13ecWq lMZeDm9mAAnkNvmVPhAU+QYsBOA41g0I/8sjbvd8= Date: Mon, 4 Feb 2019 18:21:39 +0000 From: Christopher Lameter X-X-Sender: cl@nuc-kabylake To: Jason Gunthorpe 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 In-Reply-To: <20190204175110.GA10237@ziepe.ca> Message-ID: <01000168b9be8b5a-3b4f8036-50c8-4180-b39f-9ef28cb60cce-000000@email.amazonses.com> References: <20190204052135.25784-1-jhubbard@nvidia.com> <01000168b980e880-a7d8e0db-84fb-4398-8269-149c66b701b4-000000@email.amazonses.com> <20190204175110.GA10237@ziepe.ca> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-SES-Outgoing: 2019.02.04-54.240.9.54 Feedback-ID: 1.us-east-1.fQZZZ0Xtj2+TD7V5apTT/NrT6QKuPgzCT/IC7XYgDKI=:AmazonSES X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, 4 Feb 2019, Jason Gunthorpe wrote: > 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. O_DIRECT is the same issue. O_DIRECT addresses always have been in anonymous memory or special file systems.