From: Daniel Vetter <daniel.vetter@ffwll.ch> To: Jason Gunthorpe <jgg@ziepe.ca> Cc: "DRI Development" <dri-devel@lists.freedesktop.org>, LKML <linux-kernel@vger.kernel.org>, "KVM list" <kvm@vger.kernel.org>, "Linux MM" <linux-mm@kvack.org>, "Linux ARM" <linux-arm-kernel@lists.infradead.org>, linux-samsung-soc <linux-samsung-soc@vger.kernel.org>, "open list:DMA BUFFER SHARING FRAMEWORK" <linux-media@vger.kernel.org>, linux-s390 <linux-s390@vger.kernel.org>, "Daniel Vetter" <daniel.vetter@intel.com>, "Kees Cook" <keescook@chromium.org>, "Dan Williams" <dan.j.williams@intel.com>, "Andrew Morton" <akpm@linux-foundation.org>, "John Hubbard" <jhubbard@nvidia.com>, "Jérôme Glisse" <jglisse@redhat.com>, "Jan Kara" <jack@suse.cz>, "Bjorn Helgaas" <bhelgaas@google.com>, "Linux PCI" <linux-pci@vger.kernel.org>, "Daniel Vetter" <daniel.vetter@ffwll.com> Subject: Re: [PATCH v3 12/16] PCI: Obey iomem restrictions for procfs mmap Date: Wed, 21 Oct 2020 21:24:08 +0200 [thread overview] Message-ID: <CAKMK7uEjE5sHUq0hV_bnYjPKRxYyBnty0sLre+owANGZjLJg9Q@mail.gmail.com> (raw) In-Reply-To: <20201021163702.GM36674@ziepe.ca> On Wed, Oct 21, 2020 at 6:37 PM Jason Gunthorpe <jgg@ziepe.ca> wrote: > > On Wed, Oct 21, 2020 at 05:54:54PM +0200, Daniel Vetter wrote: > > > The trouble is that io_remap_pfn adjust vma->pgoff, so we'd need to > > split that. So ideally ->mmap would never set up any ptes. > > /dev/mem makes pgoff == pfn so it doesn't get changed by remap. > > pgoff doesn't get touched for MAP_SHARED either, so there are other > users that could work like this - eg anyone mmaping IO memory is > probably OK. I was more generally thinking for io_remap_pfn_users because of the mkwrite use-case we might have in fbdev emulation in drm. > > I guess one option would be if remap_pfn_range would steal the > > vma->vm_ops pointer for itself, then it could set up the correct > > ->install_ptes hook. But there's tons of callers for that, so not sure > > that's a bright idea. > > The caller has to check that the mapping is still live, and I think > hold a lock across the remap? Auto-defering it doesn't seem feasible. Right auto-defering reopens the race, so making this work automatically is a bit much. I guess just splitting this into a setup/install part and then doing the install of all the ptes at first fault should be good enough. We don't really need a new install_pages for that, just an io_remap_pfn_range that's split in two parts. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
next prev parent reply other threads:[~2020-10-21 19:24 UTC|newest] Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-10-21 8:56 [PATCH v3 00/16] follow_pfn and other iomap races Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 01/16] drm/exynos: Stop using frame_vector helpers Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 02/16] drm/exynos: Use FOLL_LONGTERM for g2d cmdlists Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 03/16] misc/habana: Stop using frame_vector helpers Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 04/16] misc/habana: Use FOLL_LONGTERM for userptr Daniel Vetter 2020-10-23 9:12 ` Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 05/16] mm/frame-vector: Use FOLL_LONGTERM Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 06/16] media: videobuf2: Move frame_vector into media subsystem Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 07/16] mm: Close race in generic_access_phys Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 08/16] s390/pci: Remove races against pte updates Daniel Vetter 2020-10-21 9:37 ` Niklas Schnelle 2020-10-21 13:56 ` Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 09/16] mm: Add unsafe_follow_pfn Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 10/16] media/videbuf1|2: Mark follow_pfn usage as unsafe Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 11/16] vfio/type1: Mark follow_pfn " Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 12/16] PCI: Obey iomem restrictions for procfs mmap Daniel Vetter 2020-10-21 12:50 ` Jason Gunthorpe 2020-10-21 14:42 ` Daniel Vetter 2020-10-21 15:13 ` Jason Gunthorpe 2020-10-21 15:54 ` Daniel Vetter 2020-10-21 16:37 ` Jason Gunthorpe 2020-10-21 19:24 ` Daniel Vetter [this message] 2020-10-21 23:20 ` Jason Gunthorpe 2020-10-22 7:00 ` Daniel Vetter 2020-10-22 11:43 ` Jason Gunthorpe 2020-10-22 13:04 ` Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 13/16] /dev/mem: Only set filp->f_mapping Daniel Vetter 2020-10-21 18:21 ` Dan Williams 2020-10-21 8:56 ` [PATCH v3 14/16] resource: Move devmem revoke code to resource framework Daniel Vetter 2020-10-21 18:59 ` Dan Williams 2020-10-21 19:25 ` Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 15/16] sysfs: Support zapping of binary attr mmaps Daniel Vetter 2020-10-21 8:56 ` [PATCH v3 16/16] PCI: Revoke mappings like devmem Daniel Vetter 2020-10-21 12:51 ` [PATCH v3 00/16] follow_pfn and other iomap races Jason Gunthorpe
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