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Wed, 25 Mar 2026 01:46:51 -0700 (PDT) From: Askar Safin To: jack@suse.cz Cc: Liam.Howlett@oracle.com, akpm@linux-foundation.org, ardb@kernel.org, baolin.wang@linux.alibaba.com, catalin.marinas@arm.com, david@kernel.org, dev.jain@arm.com, hughd@google.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, lsf-pc@lists.linux-foundation.org, mhocko@suse.com, rppt@kernel.org, ryan.roberts@arm.com, surenb@google.com, vbabka@suse.cz, will@kernel.org, willy@infradead.org Subject: Re: [Lsf-pc] [LSF/MM/BPF TOPIC] Per-process page size Date: Wed, 25 Mar 2026 11:46:32 +0300 Message-ID: <20260325084633.906324-1-safinaskar@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 0AE9C20002 X-Stat-Signature: ppm48861cuqiwrz9yexk3dj3fi8g99xt X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1774428413-2622 X-HE-Meta: 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 Ix+TnmBK o3PbRbSx3UmEDbz+8ZGcSEDMe5Jq3GyxmrTLXhkeNUTuHMwtrL0jsuGTcOEVwym2r38k+Bwlo0dnph3Z5GcgB6BRDivQ2/5aKzWArbhhZgOx/P3yMoNEJfK1FI+LC1hnBjD/ZXCoUNu4oyZH3M2x/6oojYtwo5XpYSneSz6A0miC2bBTZaKuxfR3LjIJh573QnfqgPqIh+2z0q5MQ2g2uA0uKNOKNV7euDyOdpzVxWTE2IDSiaPsYdMnqJVYj2owYHrLuDF8oNXyaazzce7R29jQn5hqfTNChcc3O8kyL/c2f6jZghvTvPqkPFS7HsTGdoisDZknDyekWEtYR4LA0liJpJPwiIQ/rsoShTAhfL+H8za/atKhH94jw3ASAnlasKThtD0tNEfIXJNYQQjqNe0QK68/F8bVLBh59GyGXzyn8CLEdPw+bFnJV8RNC4hV+mdfP Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Jan Kara : > > 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. Splice from page cache to pipe sometimes doesn't copy data. That is why test program mentioned here may print "new": https://lore.kernel.org/all/CAHk-=wjixHw6n_R5TQWW1r0a+GgFAPGw21KMj6obkzr3qXXbYA@mail.gmail.com/ -- Askar Safin