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See http://www.infradead.org/rpr.html X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: A297880003 X-Stat-Signature: iusd7ftfk66mfpae9mfbpon6ohys6f4c X-Rspam-User: X-HE-Tag: 1748960919-128629 X-HE-Meta: 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 mzUfc4qJ 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 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 Tue, Jun 03, 2025 at 04:18:22PM +0200, Christian König wrote: > > Does it matter compared to the I/O in this case? > > It unfortunately does, see the numbers on patch 3 and 4. That's kinda weird. Why does the page table lookup tage so much time compared to normal I/O? > My question is rather if it's ok to call f_op->write_iter() and > f_op->read_iter() with pages allocated by alloc_pages(), e.g. > where drivers potentially ignore the page count and just re-use pages > as they like? read_iter and write_iter with ITER_BVEC just use the pages as source and destination of the I/O. They must not touch the refcounts or do anything fancy with them. Various places in the kernel rely on that.