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From: Askar Safin <safinaskar@gmail.com>
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	[thread overview]
Message-ID: <20260325084633.906324-1-safinaskar@gmail.com> (raw)
In-Reply-To: <pqwem5hownnfwcqrubksdwwraqbkthpzucknhavrghmw5lyszs@vdorbx4fyyaf>

Jan Kara <jack@suse.cz>:
> > 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


  reply	other threads:[~2026-03-25  8:46 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-17 14:50 [LSF/MM/BPF TOPIC] Per-process page size Dev Jain
2026-02-17 15:22 ` Matthew Wilcox
2026-02-17 15:30   ` David Hildenbrand (Arm)
2026-02-17 15:51     ` Ryan Roberts
2026-02-20  4:49     ` Matthew Wilcox
2026-02-20 16:50       ` David Hildenbrand (Arm)
2026-02-23 13:02         ` [Lsf-pc] " Jan Kara
2026-03-25  8:46           ` Askar Safin [this message]
2026-02-18  8:39   ` Dev Jain
2026-02-18  8:58     ` Dev Jain
2026-02-18  9:15       ` David Hildenbrand (Arm)
2026-02-20  9:49   ` Arnd Bergmann
2026-02-20 13:37 ` Pedro Falcato
2026-02-23  5:07   ` Dev Jain
2026-02-23 12:49     ` Pedro Falcato
2026-02-23 13:01       ` David Hildenbrand (Arm)
2026-02-23 15:18     ` Matthew Wilcox
2026-02-23 16:28       ` David Hildenbrand (Arm)
2026-02-24  4:32         ` Dev Jain
2026-02-26  7:40 ` Kalesh Singh
2026-02-26  8:45   ` Dev Jain
2026-02-27  5:11     ` Kalesh Singh
2026-03-25 12:04 ` Lorenzo Stoakes (Oracle)

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