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[156.34.48.30]) by smtp.gmail.com with ESMTPSA id y3sm131855qto.2.2020.11.04.06.00.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Nov 2020 06:00:24 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kaJKp-00GVgS-9E; Wed, 04 Nov 2020 10:00:23 -0400 Date: Wed, 4 Nov 2020 10:00:23 -0400 From: Jason Gunthorpe To: Daniel Vetter Cc: John Hubbard , DRI Development , LKML , KVM list , Linux MM , Linux ARM , linux-samsung-soc , "open list:DMA BUFFER SHARING FRAMEWORK" , Daniel Vetter , Pawel Osciak , Marek Szyprowski , Kyungmin Park , Tomasz Figa , Mauro Carvalho Chehab , Andrew Morton , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Jan Kara , Dan Williams Subject: Re: [PATCH v5 05/15] mm/frame-vector: Use FOLL_LONGTERM Message-ID: <20201104140023.GQ36674@ziepe.ca> References: <20201030100815.2269-1-daniel.vetter@ffwll.ch> <20201030100815.2269-6-daniel.vetter@ffwll.ch> <446b2d5b-a1a1-a408-f884-f17a04b72c18@nvidia.com> <1f7cf690-35e2-c56f-6d3f-94400633edd2@nvidia.com> <7f29a42a-c408-525d-90b7-ef3c12b5826c@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Sun, Nov 01, 2020 at 11:50:39PM +0100, Daniel Vetter wrote: > It's not device drivers, but everyone else. At least my understanding > is that VM_IO | VM_PFNMAP means "even if it happens to be backed by a > struct page, do not treat it like normal memory". And gup/pup_fast > happily break that. I tried to chase the history of that test, didn't > turn up anything I understood much: VM_IO isn't suppose do thave struct pages, so how can gup_fast return them? I thought some magic in the PTE flags excluded this? Jason