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See http://www.infradead.org/rpr.html X-Rspamd-Server: rspam06 X-Stat-Signature: wc75sracqfs6qhh43pninj519b16ym4m X-Rspam-User: X-Rspamd-Queue-Id: 3CDC0A0007 X-HE-Tag: 1791188617-476624 X-HE-Meta: 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 F3jUM0Km 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Sep 29, 2026 at 11:16:03AM +0200, Alexandre Ghiti wrote: > > > > > > Such a bio cannot simply drop REQ_SWAP: dm-crypt and dm-thin rely on it > > > for limit_swap_bios, which caps in-flight swap bios to avoid a memory > > > deadlock, see commit a666e5c05e7c ("dm: fix deadlock when swapping to > > > encrypted device"). > > > > Is that true? REQ_BACKGROUND very much implies the I/O can the throttled > > and thus better not be foreground paging, and thus the caller should be > > able to tolerate a failure. > > > > Yes, I agree, zswap writebacks are only best effort and in case of > failure, the compressed entry still lives. I don't see how > REQ_BACKGROUND could be an issue there? The issue is that by definition it doesn't need REQ_SWAP then. Then again the whole concept of REQ_SWAP looks sketchy to me, non-swap paging can be just as important for forward progress, so if a driver needs it, it has other issues anyway.