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Mon, 23 Feb 2026 13:02:52 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id clmgH/xPnGnCDgAAD6G6ig (envelope-from ); Mon, 23 Feb 2026 13:02:52 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 4D487A0A4A; Mon, 23 Feb 2026 14:02:52 +0100 (CET) Date: Mon, 23 Feb 2026 14:02:52 +0100 From: Jan Kara To: "David Hildenbrand (Arm)" Cc: Matthew Wilcox , Dev Jain , lsf-pc@lists.linux-foundation.org, ryan.roberts@arm.com, catalin.marinas@arm.com, will@kernel.org, ardb@kernel.org, hughd@google.com, baolin.wang@linux.alibaba.com, akpm@linux-foundation.org, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [Lsf-pc] [LSF/MM/BPF TOPIC] Per-process page size Message-ID: References: <20260217145026.3880286-1-dev.jain@arm.com> <2e68ef61-dcf2-46b2-913f-14980a104faf@kernel.org> <5f61a5fd-ab38-4635-aab8-5de515c4015a@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5f61a5fd-ab38-4635-aab8-5de515c4015a@kernel.org> X-Stat-Signature: 6cz5cw3oc9otryx8h3m5u8w4zyzh3az3 X-Rspam-User: X-Rspamd-Queue-Id: 7B51212000B X-Rspamd-Server: rspam01 X-HE-Tag: 1771851774-828847 X-HE-Meta: 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 2mE8zVzF p1ZgJH2U0Ui7n6+NB7DWC4gRBrc+30eK4Mwvf7tf63q/PEyDZutxP6/Jm0o86L+f255EhUXO7jz/a6edweNmYXsa3WJB8bCDqu1iVpGsEAXFKjbjTjcbN4Z3NCzl/uK+Gjggg+lGF+RmH3Y5OBzlaOZUWM3eT07TyIHnGyKRALOx4oXoMdUQkkL1ZXpL5oW74zawnRF5Jf96Jiy8InIsVN2zEzAPoss7K70dKs7STin86jGGolOdmOFyyDJ7ZzHhXTogTc7fDIU6La9p5k4Jf6Ra1hBn2H9dRaSzjhLzhJ6t7vBwR8tHPjcK0xGCS2vNwf489whbaWmLbFD4sjC6W6+z94Q== 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 Fri 20-02-26 17:50:44, David Hildenbrand (Arm) via Lsf-pc wrote: > On 2/20/26 05:49, Matthew Wilcox wrote: > > And if no pages from the file have been mmaped yet, they cannot be pinned > > or mlocked. > > Is there some other way for someone to block a page from getting evicted > from the pagecache? > > We have this memfd_pin_folios() thing, but I don't think we have something > comparable for ordinary pagecache files. > > ... putting them into a pipe and never reading from the pipe maybe (I assume > that's what splice() does, but not sure if it actually places the pages in > there or whether it creates a copy first)? Standard splice copies data first (it's using standard IO callbacks such as ->read_iter) so that doesn't pin page cache AFAICT. Only vmsplice(2) does but that requires mmap. Honza -- Jan Kara SUSE Labs, CR