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See http://www.infradead.org/rpr.html X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-samsung-soc , Jan Kara , KVM list , Pawel Osciak , Linux MM , John Hubbard , LKML , DRI Development , Tomasz Figa , Christoph Hellwig , Jason Gunthorpe , J??r??me Glisse , "open list:DMA BUFFER SHARING FRAMEWORK" , Daniel Vetter , Kyungmin Park , Andrew Morton , Mauro Carvalho Chehab , Dan Williams , Linux ARM , Marek Szyprowski Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Nov 04, 2020 at 04:37:58PM +0000, Christoph Hellwig wrote: > On Wed, Nov 04, 2020 at 05:26:58PM +0100, Daniel Vetter wrote: > > What we're discussing is whether gup_fast and pup_fast also obey this, > > or fall over and can give you the struct page that's backing the > > dma_mmap_* memory. Since the _fast variant doesn't check for > > vma->vm_flags, and afaict that's the only thing which closes this gap. > > And like you restate, that would be a bit a problem. So where's that > > check which Jason&me aren't spotting? > > remap_pte_range uses pte_mkspecial to set up the PTEs, and gup_pte_range > errors out on pte_special. Of course this only works for the > CONFIG_ARCH_HAS_PTE_SPECIAL case, for other architectures we do have > a real problem. Except that we don't really support pte-level gup-fast without CONFIG_ARCH_HAS_PTE_SPECIAL, and in fact all architectures selecting HAVE_FAST_GUP also select ARCH_HAS_PTE_SPECIAL, so we should be fine. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel