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[54.240.9.112]) by mx.google.com with ESMTPS id e24si3414716qtp.141.2019.02.05.11.30.22 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 05 Feb 2019 11:30:22 -0800 (PST) Received-SPF: pass (google.com: domain of 01000168bf23d0fa-f96456c7-8569-4542-9926-f91baa3c0f06-000000@amazonses.com designates 54.240.9.112 as permitted sender) client-ip=54.240.9.112; Authentication-Results: mx.google.com; dkim=pass header.i=@amazonses.com header.s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug header.b=VVg9xA+D; spf=pass (google.com: domain of 01000168bf23d0fa-f96456c7-8569-4542-9926-f91baa3c0f06-000000@amazonses.com designates 54.240.9.112 as permitted sender) smtp.mailfrom=01000168bf23d0fa-f96456c7-8569-4542-9926-f91baa3c0f06-000000@amazonses.com DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug; d=amazonses.com; t=1549395022; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References:MIME-Version:Content-Type:Feedback-ID; bh=YJTd4VU+NL7d41BJd/g/275y6kyES9bTfQmjZG0ZH+I=; b=VVg9xA+DkL+JMOKCvFEIsD3XF1phH2CCO/7+guj4mnZ3H1lP6Pn4EiG7M3TNes+Q F+/9xWOc2jtDS9z+NpYZrsT3EvFzypd6UNaSuc8OcyeiKqsf8uP8RLqRn+5P+soDC2E o4/78BCE2H2py7WW36QP0n1XyVmiXR+H7uHrRwh4= Date: Tue, 5 Feb 2019 19:30:22 +0000 From: Christopher Lameter X-X-Sender: cl@nuc-kabylake To: Ira Weiny 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 , 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: <20190204233513.GA7917@iweiny-DESK2.sc.intel.com> Message-ID: <01000168bf23d0fa-f96456c7-8569-4542-9926-f91baa3c0f06-000000@email.amazonses.com> References: <20190204052135.25784-1-jhubbard@nvidia.com> <01000168b980e880-a7d8e0db-84fb-4398-8269-149c66b701b4-000000@email.amazonses.com> <20190204233513.GA7917@iweiny-DESK2.sc.intel.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: 2019.02.05-54.240.9.112 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, Ira Weiny 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. > > > > Can we just disable RDMA to regular filesystems? Regular filesystems > > should have full control of the write back and dirty status of their > > pages. > > That may be a solution to the corruption/crashes but it is not a solution which > users want to see. RDMA directly to file systems (specifically DAX) is a use > case we have seen customers ask for. DAX is a special file system that does not use writeback for the DAX mappings. Thus it could be an exception. And the pages are already pinned.