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See http://www.infradead.org/rpr.html X-Rspam-User: X-Stat-Signature: tyg99i9os61rdc87q573438kf7zdhsmx X-Rspamd-Queue-Id: 2F95940002 X-Rspamd-Server: rspam09 X-HE-Tag: 1760960673-446084 X-HE-Meta: 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 a4wAGjCW PTUPpy1ELD0Qkx0WGxxsWz7YEGwCdN6UquHInmqzj3nYe8fr2DTjYJycdLSu253e9QCQpP8j0ntSkQb+7+YjOWGL2ZkIOPOMJPw9fiXmc9EwPjJUGSx716BLjHAanFesLVlRY7osLvKZzp3x6vI5vd0RjKJjVs4hE+0pvuDT3flmqLnKrMTi+Ae/HD71xNL7SUgWVh6BnTIdGsq9/6+yd6wnoyFoD58vOYorgjeZZCxdK4O7pi4q4FuqdBH51ufeCQ3IIpchQSIK3E6bxbYi0plXv9Hs0AU/C5zVA3WzSUCJu/L8x66C6CIJSmlkavxEsQnjxNXf/sHAUkaYWkkAPpZc6fRTsxAZqAZiRyT0S0TeNItocnosFfvCdapuC+SqmaOSkcbuvA8FmQ9EZ5/Cgd3lC5zAjmn/PlheUvjz4wbWL4FH0OIfyXMe6fkQkkOIIHCZjxcNOF6sFGp5go+AIbTzasZrsUlS25JjR 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: List-Subscribe: List-Unsubscribe: On Mon, Oct 20, 2025 at 01:16:39PM +0200, Jan Kara wrote: > Hmm, this is an interesting twist in the problems with pinned pages - so > far I was thinking about problems where pinned page cache page gets > modified (e.g. through DIO or RDMA) and this causes checksum failures if > it races with writeback. If I understand you right, now you are concerned > about a situation where some page is used as a buffer for direct IO write > / RDMA and it gets modified while the DMA is running which causes checksum > mismatch? Really all of the above. Even worse this can also happen for reads, e.g. when the parity or checksum is calculated in the user buffer. > Writeprotecting the buffer before the DIO starts isn't that hard > to do (although it has a non-trivial cost) but we don't have a mechanism to > make sure the page cannot be writeably mapped while it is pinned (and > avoiding that without introducing deadlocks would be *fun*). Well, this goes back to the old idea of maybe bounce buffering in that case?