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See http://www.infradead.org/rpr.html X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 159D540007 X-Stat-Signature: 5unz44qkuesi6nwowd56wfu5eukygap9 X-Rspam-User: X-HE-Tag: 1738647411-752752 X-HE-Meta: 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 DrIKYzy+ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Simona, On Mon, Feb 03, 2025 at 04:49:34PM +0100, Simona Vetter wrote: > > Could we go one step further and entirely drop the struct page? Similar to > unmap_mapping_range for VM_SPECIAL mappings, except it only updates the > write protection. The reason is that ideally we'd like fbdev defio to > entirely get rid of any struct page usage, because with some dma_alloc() > memory regions there's simply no struct page for them (it's a carveout). Umm, for dma_alloc* where * is not _pages you never can get a page or PFN form them. They are block boxes and drivers must not attempt to translated them into either a page or PFN or things will go wrong. Only the kernel virtual address and dma_address may be used. > See e.g. Sa498d4d06d6 ("drm/fbdev-dma: Only install deferred I/O if > necessary") for some of the pain this has caused. The commit hash is corrupted, I guess this is 5a498d4d06d6 as the subject line matches. And that commit (just like the code it is trying to fix) is completely broken as it violates the above.