From: Christoph Hellwig <hch@infradead.org>
To: John Hubbard <jhubbard@nvidia.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Peter Xu <peterx@redhat.com>, Jason Gunthorpe <jgg@ziepe.ca>,
David Hildenbrand <david@redhat.com>,
Lukas Bulwahn <lukas.bulwahn@gmail.com>, Jan Kara <jack@suse.cz>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Alex Williamson <alex.williamson@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, Jason Gunthorpe <jgg@nvidia.com>
Subject: Re: [PATCH v3 4/4] mm/gup: remove get_user_pages_locked()
Date: Thu, 3 Feb 2022 06:01:36 -0800 [thread overview]
Message-ID: <YfvgQHewEbN3lR33@infradead.org> (raw)
In-Reply-To: <20220203093232.572380-5-jhubbard@nvidia.com>
On Thu, Feb 03, 2022 at 01:32:32AM -0800, John Hubbard wrote:
> There is only one caller of get_user_pages_locked(). The purpose of
> get_user_pages_locked() is to allow for unlocking the mmap_lock when
> reading a page from the disk during a page fault (hidden behind
> VM_FAULT_RETRY). The idea is to reduce contention on the heavily-used
> mmap_lock. (Thanks to Jan Kara for clearly pointing that out, and in
> fact I've used some of his wording here.)
>
> However, it is unlikely for lookup_node() to take a page fault. With
> that in mind, change over to calling get_user_pages_fast(). This
> simplifies the code, runs a little faster in the expected case, and
> allows removing get_user_pages_locked() entirely.
Maybe split the lookup_node changes into a separate patch, as that
allows to document that change even better.
next prev parent reply other threads:[~2022-02-03 14:01 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-03 9:32 [PATCH v3 0/4] mm/gup: some cleanups John Hubbard
2022-02-03 9:32 ` [PATCH v3 1/4] mm: Fix invalid page pointer returned with FOLL_PIN gups John Hubbard
2022-02-03 12:10 ` Claudio Imbrenda
2022-02-03 21:25 ` John Hubbard
2022-02-03 14:00 ` Christoph Hellwig
2022-02-03 21:13 ` John Hubbard
2022-02-03 9:32 ` [PATCH v3 2/4] mm/gup: clean up follow_pfn_pte() slightly John Hubbard
2022-02-03 13:31 ` Claudio Imbrenda
2022-02-03 20:53 ` John Hubbard
2022-02-03 13:53 ` Jan Kara
2022-02-03 15:01 ` Jason Gunthorpe
2022-02-03 15:18 ` Matthew Wilcox
2022-02-03 21:19 ` John Hubbard
2022-02-03 9:32 ` [PATCH v3 3/4] mm/gup: remove unused pin_user_pages_locked() John Hubbard
2022-02-03 11:52 ` Claudio Imbrenda
2022-02-03 9:32 ` [PATCH v3 4/4] mm/gup: remove get_user_pages_locked() John Hubbard
2022-02-03 12:04 ` Claudio Imbrenda
2022-02-03 14:01 ` Christoph Hellwig [this message]
2022-02-03 21:27 ` John Hubbard
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YfvgQHewEbN3lR33@infradead.org \
--to=hch@infradead.org \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=alex.williamson@redhat.com \
--cc=david@redhat.com \
--cc=imbrenda@linux.ibm.com \
--cc=jack@suse.cz \
--cc=jgg@nvidia.com \
--cc=jgg@ziepe.ca \
--cc=jhubbard@nvidia.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=lukas.bulwahn@gmail.com \
--cc=peterx@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox