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bh=QkxD4jDFwjLSBHfJ/c7FKLTS33arAD1vzMDqCSf5Pqw=; b=WecT/scqjLIK4s1VjLSGGyFo6Jr1XXzXXa7ew7a08lM3Cc2LHE+s4zmMPCPIvNECejz+09 87fbFNALX/Zp+UJRamTk9VK8yhJr+tFbUFAlSdpMq6+uNqrfb6Pxl8tTlZf5YXh6iTKo+f TWLO/fAsZChUP7p2Ke4ZEC50klOeE1NBd8F8IdQ+f42jv/Ri4LXiAAZerNVFEuO0f0OTAP 49SNHsfXxg7npfLUnrb3cg3yme5cB6bsNk9EJ0P5TDYVdftfjG8QemHEHV1r9IdMKbgoSp cuiem2FT9GMotBK2ZTViDARfY+e5A+bTiwA6e3hr1Rdw1c88Odvy6BIG1UPpsQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1684007817; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=QkxD4jDFwjLSBHfJ/c7FKLTS33arAD1vzMDqCSf5Pqw=; b=SUX0/ToMzEcB41KnS0g0Ax0kdf6JxQPb/f2pebxSdCW+QrA33POroMty+gImglWABdG5dz NygQwc3rBZelmEAQ== To: Matthew Wilcox , Ingo Molnar , Peter Zijlstra , Darren Hart , Davidlohr Bueso , =?utf-8?Q?Andr=C3=A9?= Almeida Cc: linux-kernel@vger.kernel.org, Jason Gunthorpe , linux-mm@kvack.org Subject: Re: Futexes & Folios In-Reply-To: References: Date: Sat, 13 May 2023 21:56:56 +0200 Message-ID: <87cz349f93.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 4DD411C0006 X-Stat-Signature: 4f5djg767mjndqumt45jom6jzgwg8tk6 X-HE-Tag: 1684007818-231899 X-HE-Meta: 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 RqdDZ6l4 k+JN7UoCcV/uugfFpzsMN7GUU6ShAEhAy0Edf+j0QJeDJq8o= 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: On Sat, May 13 2023 at 17:16, Matthew Wilcox wrote: > Here's a patch which converts the futex code from using pages to using > folios. I do have some questions. > > - I assume we really do want to base the key on the page offset of the > futex in the file. That is, it's not good enough to base the key > on the folio's index because the folio can be split after setting up > the key, and if it is we'd then fail to find the futex later. Correct. > - In hugetlbfs, it doesn't matter whether the pgoff is based on base > pages or huge page size -- as long as it's consistent between > invocations, everything will work Yes. The patch looks sane, but I need to have a look with brain more awake Thanks, tglx