From: Christoph Hellwig <hch@infradead.org>
To: John Hubbard <jhubbard@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>,
David Howells <dhowells@redhat.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
willy@infradead.org, linux-mm@kvack.org,
Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org
Subject: Re: Does GUP page unpinning have to be done in the pinning context?
Date: Sun, 6 Apr 2025 23:39:01 -0700 [thread overview]
Message-ID: <Z_NzBWIy-QvFBQZk@infradead.org> (raw)
In-Reply-To: <dcb80dc4-a9f7-44d8-b88c-7221ea29deab@nvidia.com>
On Fri, Apr 04, 2025 at 09:59:40AM -0700, John Hubbard wrote:
> > gup_put_folio() seems to only rely on per-folio information (esp.
> > node_stat_mod_folio).
> >
> > So there should not be such a context requirement.
>
> That is correct. The essence of gup/pup is that it operates on
> struct pages, and doesn't have any "moral" connection to higher
> layers or additional process context.
Hmm, indeed. I misremembered why the block based direct I/O code is
doing the process context offload, which is to call set_page_dirty to
redirty pages where the dirty bit was cleared during direct I/O.
Which I think now that all block based file systems use FOLL_PIN
shouldn't be needed anymore, because no one can clear the dirty bit
while the folios are pinned?
next prev parent reply other threads:[~2025-04-07 6:39 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-04 10:20 David Howells
2025-04-04 10:29 ` David Hildenbrand
2025-04-04 16:59 ` John Hubbard
2025-04-07 6:39 ` Christoph Hellwig [this message]
2025-04-10 2:56 ` John Hubbard
2025-04-10 7:28 ` Christoph Hellwig
2025-04-10 19:11 ` John Hubbard
2025-04-10 19:14 ` Matthew Wilcox
2025-04-10 19:34 ` John Hubbard
2025-05-12 6:21 ` Christoph Hellwig
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