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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qVsP0-007xF4-Th; Tue, 15 Aug 2023 11:39:58 +0000 Date: Tue, 15 Aug 2023 12:39:58 +0100 From: Matthew Wilcox To: David Hildenbrand Cc: Andrew Morton , Jens Axboe , io-uring@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 9/9] mm: Free up a word in the first tail page Message-ID: References: <20230815032645.1393700-1-willy@infradead.org> <20230815032645.1393700-10-willy@infradead.org> <86579ba0-057e-37bd-e2ec-bd705026daa5@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <86579ba0-057e-37bd-e2ec-bd705026daa5@redhat.com> X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 44AD580020 X-Stat-Signature: 5wapjh1a73qsyqy381oefg4biftkgayo X-HE-Tag: 1692099606-888730 X-HE-Meta: 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 9ep1Fwme q5r2tx9McJCfCpetJDHvvXj4yax9gkEyX8JsFa6UHp5wdA75idpnrDz7dnqSvZUShOhw15KXNDpCL3UBm0oxd3hzN69RSAzswAOFxs4isJ8UMDlIkXEVyap9yUkeAl2JrmWe92qAvcz4l1/O2GizU/UrCIRA1DGgDTNfxm5eE89uHmLPw1kseUp74alE0ynn/cHsKG97acrKlOjo= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000063, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Aug 15, 2023 at 09:59:08AM +0200, David Hildenbrand wrote: > On 15.08.23 05:26, Matthew Wilcox (Oracle) wrote: > > Store the folio order in the low byte of the flags word in the first > > tail page. This frees up the word that was being used to store the > > order and dtor bytes previously. > > > > Is there still a free flag in page[1] after this change? I need one, at > least for a prototype I'm working on. (could fallback to page[2], though > eventually, though) There are only ~13 flags used in page[1] at this point. Plenty of space.