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[54.240.9.33]) by mx.google.com with ESMTPS id 40si4482322qvu.207.2019.02.04.09.14.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 04 Feb 2019 09:14:20 -0800 (PST) Received-SPF: pass (google.com: domain of 01000168b980e880-a7d8e0db-84fb-4398-8269-149c66b701b4-000000@amazonses.com designates 54.240.9.33 as permitted sender) client-ip=54.240.9.33; Authentication-Results: mx.google.com; dkim=pass header.i=@amazonses.com header.s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug header.b=fNHfgZqQ; spf=pass (google.com: domain of 01000168b980e880-a7d8e0db-84fb-4398-8269-149c66b701b4-000000@amazonses.com designates 54.240.9.33 as permitted sender) smtp.mailfrom=01000168b980e880-a7d8e0db-84fb-4398-8269-149c66b701b4-000000@amazonses.com DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug; d=amazonses.com; t=1549300459; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References:MIME-Version:Content-Type:Feedback-ID; bh=rRIYgpkoOU9OXyNN7jqzPWMWewZIFQicQrnhsy101kA=; b=fNHfgZqQCAIPedvEn9/V09tGYqNz+41uFUDzEvPKPtLzF+oYs+UPyt9aF1iKxinD bh8DOvBrneM8djIV8FXwYLhmyfi1OX1or69dkUp1EME8XHHZE50Sl5/y2eNyzaDG0p9 sgutHg/yTiJ/yAYnzb5sp8+EcpQzIQIv6gS10zzU= Date: Mon, 4 Feb 2019 17:14:19 +0000 From: Christopher Lameter X-X-Sender: cl@nuc-kabylake To: john.hubbard@gmail.com cc: Andrew Morton , linux-mm@kvack.org, Al Viro , Christian Benvenuti , Christoph Hellwig , Dan Williams , Dave Chinner , Dennis Dalessandro , Doug Ledford , Jan Kara , Jason Gunthorpe , 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: <20190204052135.25784-1-jhubbard@nvidia.com> Message-ID: <01000168b980e880-a7d8e0db-84fb-4398-8269-149c66b701b4-000000@email.amazonses.com> References: <20190204052135.25784-1-jhubbard@nvidia.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-SES-Outgoing: 2019.02.04-54.240.9.33 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: 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. Can we just disable RDMA to regular filesystems? Regular filesystems should have full control of the write back and dirty status of their pages. Special filesystems that do not actually do write back (like hugetlbfs), mmaped raw device files and anonymous allocations are fine.