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[54.240.9.114]) by mx.google.com with ESMTPS id 13si3836613qtu.390.2019.02.04.08.59.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 04 Feb 2019 08:59:17 -0800 (PST) Received-SPF: pass (google.com: domain of 01000168b97322ff-7c681a52-566f-4de1-ba1e-0a045b7f3622-000000@amazonses.com designates 54.240.9.114 as permitted sender) client-ip=54.240.9.114; Authentication-Results: mx.google.com; dkim=pass header.i=@amazonses.com header.s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug header.b=PczSozFF; spf=pass (google.com: domain of 01000168b97322ff-7c681a52-566f-4de1-ba1e-0a045b7f3622-000000@amazonses.com designates 54.240.9.114 as permitted sender) smtp.mailfrom=01000168b97322ff-7c681a52-566f-4de1-ba1e-0a045b7f3622-000000@amazonses.com DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug; d=amazonses.com; t=1549299557; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References:MIME-Version:Content-Type:Feedback-ID; bh=dFVSi6eAG6s4EOjNzfgj7jQYa7+0xeruK9bRGAAvn/0=; b=PczSozFFqeRL7X+LTVq/x4SUbvHWdcH7f444zjDojJHuUSurhYyjMpazh91nqYfc IaVvmvTRYQS6v/LqWHm6LnWzaz3MZ89JxulkbSfH0GWidNhdvPRq1ddxLuTj2iYqGSM lkgO3lvUPBKUvTT6vy7WFXpTOY6Rt2jkSXfkysN8= Date: Mon, 4 Feb 2019 16:59:17 +0000 From: Christopher Lameter X-X-Sender: cl@nuc-kabylake To: Christoph Hellwig cc: john.hubbard@gmail.com, Andrew Morton , linux-mm@kvack.org, Al Viro , Christian Benvenuti , 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: <20190204161201.GA6840@infradead.org> Message-ID: <01000168b97322ff-7c681a52-566f-4de1-ba1e-0a045b7f3622-000000@email.amazonses.com> References: <20190204052135.25784-1-jhubbard@nvidia.com> <01000168b94439c0-28d5e096-718d-4e39-a7af-20d0a6d7b768-000000@email.amazonses.com> <20190204161201.GA6840@infradead.org> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-SES-Outgoing: 2019.02.04-54.240.9.114 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, Christoph Hellwig wrote: > On Mon, Feb 04, 2019 at 04:08:02PM +0000, Christopher Lameter wrote: > > It may be worth noting a couple of times in this text that this was > > designed for anonymous memory and that such use is/was ok. We are talking > > about a use case here using mmapped access with a regular filesystem that > > was not initially intended. The mmapping of from the hugepages filesystem > > is special in that it is not a device that is actually writing things > > back. > > > > Any use with a filesystem that actually writes data back to a medium > > is something that is broken. > > Saying it was not intended seems rather odd, as it was supported > since day 0 and people made use of it. Well until last year I never thought there was a problem because I considered it separate from regular filesystem I/O.