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
next prev parent reply other threads:[~2026-10-05 18:46 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-02 1:21 [PATCH] pid: use READ_ONCE() in pid_alive() 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]
2026-10-12 9:13 ` Christian Brauner
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