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Tue, 19 Jan 2021 12:24:14 +0000 (UTC) Received: from cust-b5b5937f ([IPv6:fc0c:c16d:66b8:757f:c639:739b:9d66:799d]) by smtp-cloud7.xs4all.net with ESMTPA id 1q3JlOl5LyutM1q3MlbVVy; Tue, 19 Jan 2021 13:24:13 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=xs4all.nl; s=s2; t=1611059053; bh=+fygwg8H7qkyKanjBFzInEqDikPrCtVia5ztmXeuT8o=; h=Subject:To:From:Message-ID:Date:MIME-Version:Content-Type:From: Subject; b=esWbI+Lh9FRvuG9LpVYDuouJ84+y5SVFATzQP7ZpAkWlKhxpMQNv10g7tZk+Q+4GR P8w0iKSjARrqozBk9TMk4qupccz3HMw/pPa5j+Fl4C2W0pgaEOFIATNA5dfqmNbXpF WY3dgySHr2MM3+6svDtBqw3Cm53j9ZKlcznqjLsgYdpTtvUnDnYFt00lTZiImdL2fY qY1XJPsfQLCx3vnp/zkfosk3P0gx6P0mVbHxoub0/O3N+aYXqUBlwVZ01FyUjwj1I0 OZ20uGwGN94AfvQR5wgjFi/ySkQn4HCvdPm/riMHsIyPvQ/Hw151NoHZMXG5h6/u3B ZllT5HuMu4+8A== Subject: Re: [PATCH v7 14/17] media/videobuf1|2: Mark follow_pfn usage as unsafe To: Daniel Vetter , DRI Development , LKML Cc: kvm@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org, Tomasz Figa , Daniel Vetter , Jason Gunthorpe , Kees Cook , Dan Williams , Andrew Morton , John Hubbard , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Jan Kara , Pawel Osciak , Marek Szyprowski , Kyungmin Park , Laurent Dufour , Vlastimil Babka , Daniel Jordan , Michel Lespinasse References: <20201127164131.2244124-1-daniel.vetter@ffwll.ch> <20201127164131.2244124-15-daniel.vetter@ffwll.ch> From: Hans Verkuil Message-ID: Date: Tue, 19 Jan 2021 13:24:05 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20201127164131.2244124-15-daniel.vetter@ffwll.ch> Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-CMAE-Envelope: MS4xfA1H6w7Z451hXz5uBfC+T4CILwukWC7IM/06HM55r5dwzXzD5s4d8wprZRF6kMCTJKToPwR+OFR57hUr5TUeAa3J/b4Bano5cXG5JJs7aDyySvyBQ7iT AF6NJi1hvvqh1FElksqvzLVa/QmOEEejZBgjFwsoa8P3BlX71aUZg55UgN1CoKfvJigaVMx8OmJVZTP1TBgBzYBEZA+0dH6f1b1DMDgA9kXqoDqQfIJqtbCX qHojNYKAiISwBmDYuSZMkSH7KYRNIIB59C3sKlux+Osh+dIvr5KeKL/UVyQNN5t4C8bA3xzI7WdxGoWOTrcrh6osz7j5RinbLE8qyeEUJUyvvWjXKkpd7dqS HMIEDbWiUVhRUKJ1yDeGKCpWevlCpEVMVzY1pNK0/aVSSfNEBvtodYg6CYCokOhjJHvuA+Ep4e+YV4DPrzHET+/xc+NX8AyQiHwb8/yP2YmEZJ49rfgQR9BP dr/7nk6Q/Zh1zkv3OibjwZY9c+4YhA+0B7uhgqimrkbKOf8Rigw2QOU+Ca/UadrwBpoSe8JeVoEhBEL9Z1DvGPDVJmztfvzZh/WKgR3U/UdzLA58H6XYG2Wi kRopGvfHjGH7BGq7rfl3p2JRUv4RPzrY67wfHIz7CJCMySBHEhQmO0DqCexzJwuN7qVDQQUew+dVW+zy8VfPtcLvnQ/ulL2+sYo0AsauVMOoEKmJsD13zo8F BwOGLGocDuv11A3T9etYvQWCfQotxHdMIivYlD9K45bjGngn5VQTZJEBfHREoydJ8pRl5Zubmv1dwvrtHzJ5cUaN75JDMp0+rY6t7CQSF6ElQBaS/BkwGvqT E/8oCoh/4PmJ0q6wWIfjNWnYVoGo3VhXp1URyLLFriMg9vsz5Zk8hKxx6nVgqUGGVM+9vX7XOQ6WrUu2nFalkCfyREoU2d7TZo3kbyVR1cFUVs4KSoSVdkYX 9CdJyh8ZOIugxyoIdE14LTtUXncHFwG8YxkQ+bn6EZL1uWAR Content-Transfer-Encoding: quoted-printable 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 27/11/2020 17:41, Daniel Vetter wrote: > The media model assumes that buffers are all preallocated, so that > when a media pipeline is running we never miss a deadline because the > buffers aren't allocated or available. >=20 > This means we cannot fix the v4l follow_pfn usage through > mmu_notifier, without breaking how this all works. The only real fix > is to deprecate userptr support for VM_IO | VM_PFNMAP mappings and > tell everyone to cut over to dma-buf memory sharing for zerocopy. >=20 > userptr for normal memory will keep working as-is, this only affects > the zerocopy userptr usage enabled in 50ac952d2263 ("[media] > videobuf2-dma-sg: Support io userptr operations on io memory"). >=20 > Acked-by: Tomasz Figa Acked-by: Hans Verkuil Regards, Hans > Signed-off-by: Daniel Vetter > Cc: Jason Gunthorpe > Cc: Kees Cook > Cc: Dan Williams > Cc: Andrew Morton > Cc: John Hubbard > Cc: J=C3=A9r=C3=B4me Glisse > Cc: Jan Kara > Cc: Dan Williams > Cc: linux-mm@kvack.org > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-samsung-soc@vger.kernel.org > Cc: linux-media@vger.kernel.org > Cc: Pawel Osciak > Cc: Marek Szyprowski > Cc: Kyungmin Park > Cc: Tomasz Figa > Cc: Laurent Dufour > Cc: Vlastimil Babka > Cc: Daniel Jordan > Cc: Michel Lespinasse > Signed-off-by: Daniel Vetter > -- > v3: > - Reference the commit that enabled the zerocopy userptr use case to > make it abundandtly clear that this patch only affects that, and not > normal memory userptr. The old commit message already explained that > normal memory userptr is unaffected, but I guess that was not clear > enough. > --- > drivers/media/common/videobuf2/frame_vector.c | 2 +- > drivers/media/v4l2-core/videobuf-dma-contig.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) >=20 > diff --git a/drivers/media/common/videobuf2/frame_vector.c b/drivers/me= dia/common/videobuf2/frame_vector.c > index a0e65481a201..1a82ec13ea00 100644 > --- a/drivers/media/common/videobuf2/frame_vector.c > +++ b/drivers/media/common/videobuf2/frame_vector.c > @@ -70,7 +70,7 @@ int get_vaddr_frames(unsigned long start, unsigned in= t nr_frames, > break; > =20 > while (ret < nr_frames && start + PAGE_SIZE <=3D vma->vm_end) { > - err =3D follow_pfn(vma, start, &nums[ret]); > + err =3D unsafe_follow_pfn(vma, start, &nums[ret]); > if (err) { > if (ret =3D=3D 0) > ret =3D err; > diff --git a/drivers/media/v4l2-core/videobuf-dma-contig.c b/drivers/me= dia/v4l2-core/videobuf-dma-contig.c > index 52312ce2ba05..821c4a76ab96 100644 > --- a/drivers/media/v4l2-core/videobuf-dma-contig.c > +++ b/drivers/media/v4l2-core/videobuf-dma-contig.c > @@ -183,7 +183,7 @@ static int videobuf_dma_contig_user_get(struct vide= obuf_dma_contig_memory *mem, > user_address =3D untagged_baddr; > =20 > while (pages_done < (mem->size >> PAGE_SHIFT)) { > - ret =3D follow_pfn(vma, user_address, &this_pfn); > + ret =3D unsafe_follow_pfn(vma, user_address, &this_pfn); > if (ret) > break; > =20 >=20