From: David Laight <david.laight.linux@gmail.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Babanpreet Singh <bbnpreetsingh@gmail.com>,
Christian Brauner <brauner@kernel.org>,
Pavel Tikhomirov <ptikhomirov@virtuozzo.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
syzbot+c382ee653fd70f5cf1bb@syzkaller.appspotmail.com
Subject: Re: [PATCH] pid: use READ_ONCE() in pid_alive()
Date: Mon, 5 Oct 2026 19:46:55 +0100 [thread overview]
Message-ID: <20261005194655.18e8d3a2@pumpkin> (raw)
In-Reply-To: <asO8TiCfByNjBHWK@redhat.com>
On Mon, 5 Oct 2026 17:03:42 +0200
Oleg Nesterov <oleg@redhat.com> wrote:
> On 10/04, David Laight wrote:
...
> > If the 'add code' all the readers and have to hold the lock then does that
> > leave anything other than task exit doing an rcu-delete.
> > I wouldn't have though acquiring the lock in the task exit code would
> > be noticeable.
>
> Still can't understand. The exiting task does take tasklist when it calls
> detach_pid().
I think I've confused myself :-)
The delete needs the lock to avoid corrupting the list.
It would be safe for an rcu protected reader - but it doesn't help you.
David
prev parent reply other threads:[~2026-10-05 18:46 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-02 1:21 Babanpreet Singh
2026-10-02 6:33 ` Bradley Morgan
2026-10-02 11:59 ` Oleg Nesterov
2026-10-03 17:22 ` David Laight
2026-10-04 10:55 ` Oleg Nesterov
2026-10-04 11:11 ` Oleg Nesterov
2026-10-04 11:51 ` David Laight
2026-10-04 13:14 ` Oleg Nesterov
2026-10-04 13:31 ` David Laight
2026-10-05 15:03 ` Oleg Nesterov
2026-10-05 18:46 ` David Laight [this message]
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=20261005194655.18e8d3a2@pumpkin \
--to=david.laight.linux@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=bbnpreetsingh@gmail.com \
--cc=brauner@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=oleg@redhat.com \
--cc=ptikhomirov@virtuozzo.com \
--cc=syzbot+c382ee653fd70f5cf1bb@syzkaller.appspotmail.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
all inboxes | Powered by JetHome®