From: "Ahmed S. Darwish" <a.darwish@linutronix.de>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: linux-kernel@vger.kernel.org, Peter Xu <peterx@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
Christoph Hellwig <hch@lst.de>, Hugh Dickins <hughd@google.com>,
Jan Kara <jack@suse.cz>, Jann Horn <jannh@google.com>,
John Hubbard <jhubbard@nvidia.com>,
Kirill Shutemov <kirill@shutemov.name>,
Kirill Tkhai <ktkhai@virtuozzo.com>,
Leon Romanovsky <leonro@nvidia.com>,
Linux-MM <linux-mm@kvack.org>, Michal Hocko <mhocko@suse.com>,
Oleg Nesterov <oleg@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
"Sebastian A. Siewior" <bigeasy@linutronix.de>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v3 2/2] mm: prevent gup_fast from racing with COW during fork
Date: Fri, 6 Nov 2020 18:17:16 +0100 [thread overview]
Message-ID: <20201106171716.GA91138@lx-t490> (raw)
In-Reply-To: <2-v3-7358966cab09+14e9-gup_fork_jgg@nvidia.com>
Hi Jason,
On Fri, Nov 06, 2020 at 11:55:14AM -0400, Jason Gunthorpe wrote:
...
> + if (gup_flags & FOLL_PIN) {
> + seq = raw_read_seqcount(¤t->mm->write_protect_seq);
> + if (seq & 1)
> + return 0;
> + }
> +
...
> + if (gup_flags & FOLL_PIN) {
> + if (read_seqcount_t_retry(¤t->mm->write_protect_seq,
> + seq)) {
> + unpin_user_pages(pages, nr_pinned);
> + return 0;
> + }
> + }
From seqlock.h:
/**
* raw_read_seqcount() - read the raw seqcount_t counter value
* ...
* Return: count to be passed to read_seqcount_retry()
*/
#define raw_read_seqcount(s)
Please avoid using the internal API (read_seqcount_*t*_retry) and just
use read_seqcount_retry() as the documentation suggests.
(I guess you just missed changing that last one... I'm in process of
changing all these "*_seqcount_t_*" stuff to "do_*" as we talked on the
v2 thread. Hopefully there will be no more confusion after that.)
Kind regards,
--
Ahmed S. Darwish
Linutronix GmbH
next prev parent reply other threads:[~2020-11-06 17:17 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <0-v3-7358966cab09+14e9-gup_fork_jgg@nvidia.com>
2020-11-06 15:55 ` [PATCH v3 1/2] mm: reorganize internal_get_user_pages_fast() Jason Gunthorpe
[not found] ` <2-v3-7358966cab09+14e9-gup_fork_jgg@nvidia.com>
2020-11-06 17:17 ` Ahmed S. Darwish [this message]
2020-11-06 18:52 ` [PATCH v3 0/2] Add a seqcount between gup_fast and copy_page_range() Ahmed S. Darwish
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=20201106171716.GA91138@lx-t490 \
--to=a.darwish@linutronix.de \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=aneesh.kumar@linux.ibm.com \
--cc=bigeasy@linutronix.de \
--cc=hch@lst.de \
--cc=hughd@google.com \
--cc=jack@suse.cz \
--cc=jannh@google.com \
--cc=jgg@nvidia.com \
--cc=jhubbard@nvidia.com \
--cc=kirill@shutemov.name \
--cc=ktkhai@virtuozzo.com \
--cc=leonro@nvidia.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.com \
--cc=oleg@redhat.com \
--cc=peterx@redhat.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
/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;
as well as URLs for NNTP newsgroup(s).