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[192.55.52.136]) by mx.google.com with ESMTPS id j21si1410929pfn.277.2019.02.04.15.35.36 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 04 Feb 2019 15:35:36 -0800 (PST) Received-SPF: pass (google.com: domain of ira.weiny@intel.com designates 192.55.52.136 as permitted sender) client-ip=192.55.52.136; Authentication-Results: mx.google.com; spf=pass (google.com: domain of ira.weiny@intel.com designates 192.55.52.136 as permitted sender) smtp.mailfrom=ira.weiny@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 04 Feb 2019 15:35:35 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,560,1539673200"; d="scan'208";a="113707140" Received: from iweiny-desk2.sc.intel.com ([10.3.52.157]) by orsmga006.jf.intel.com with ESMTP; 04 Feb 2019 15:35:34 -0800 Date: Mon, 4 Feb 2019 15:35:14 -0800 From: Ira Weiny 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 , 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 Message-ID: <20190204233513.GA7917@iweiny-DESK2.sc.intel.com> 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/1.11.1 (2018-12-01) 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, 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. I think this is the correct path toward supporting this use case. Ira