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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id h10si363823pgp.4.2019.02.04.08.12.04 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 04 Feb 2019 08:12:05 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of batv+4d538b5499ac5f299814+5643+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=IIH8Libj; spf=pass (google.com: best guess record for domain of batv+4d538b5499ac5f299814+5643+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=BATV+4d538b5499ac5f299814+5643+infradead.org+hch@bombadil.srs.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=oFN+KQoRP/AZ1fMH9/ahgnepZfE4l2bgG1MGqmiAXis=; b=IIH8LibjpIBarmSURFAhpGGHO 6jYB4GH/OrYb9bjQOV28kRqaV6jviv7pI2JsEQkNq5Im+9xjCZSveKgs6GrOHfZzOr1/P43ErwTbY qOecBn0wKyQUfSn6ZzCiVF76G4UcuU1P5zYtisBhgJMcHcILQwUuVd54UkZm/uug0wIpRdDcySrbk HOARpCDt5dxiOqD7Awl+Y5kwvZwZQhuPkX7NUjT7pNTbk8bzFRA7FJ0KgOFYJIcDoh27sWeHUeuf2 cmfW6x/FNFlkLG8XNrxLiN1O9frNiXmpaAFsSkg6uf3THD8RCKMPXagf4+CMDyz0bYlS3cel/Crh1 AjXfAJ9ow==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gqgqn-0003SS-Di; Mon, 04 Feb 2019 16:12:01 +0000 Date: Mon, 4 Feb 2019 08:12:01 -0800 From: Christoph Hellwig 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: <20190204161201.GA6840@infradead.org> References: <20190204052135.25784-1-jhubbard@nvidia.com> <01000168b94439c0-28d5e096-718d-4e39-a7af-20d0a6d7b768-000000@email.amazonses.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <01000168b94439c0-28d5e096-718d-4e39-a7af-20d0a6d7b768-000000@email.amazonses.com> User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html 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 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.