From: Oleg Nesterov <oleg@redhat.com>
To: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc: linux-kernel@vger.kernel.org,
Suren Baghdasaryan <surenb@google.com>,
kernel-team@android.com, Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Christian Brauner <christian@brauner.io>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH RFC v1] pidfd: fix a race in setting exit_state for pidfd polling
Date: Fri, 19 Jul 2019 18:14:05 +0200 [thread overview]
Message-ID: <20190719161404.GA24170@redhat.com> (raw)
In-Reply-To: <20190717172100.261204-1-joel@joelfernandes.org>
it seems that I missed something else...
On 07/17, Joel Fernandes (Google) wrote:
>
> @@ -1156,10 +1157,11 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
> ptrace_unlink(p);
>
> /* If parent wants a zombie, don't release it now */
> - state = EXIT_ZOMBIE;
> + p->exit_state = EXIT_ZOMBIE;
> if (do_notify_parent(p, p->exit_signal))
> - state = EXIT_DEAD;
> - p->exit_state = state;
> + p->exit_state = EXIT_DEAD;
> +
> + state = p->exit_state;
> write_unlock_irq(&tasklist_lock);
why do you think we also need to change wait_task_zombie() ?
pidfd_poll() only needs the exit_state != 0 check, we know that it
is not zero at this point. Why do we need to change exit_state before
do_notify_parent() ?
Oleg.
next prev parent reply other threads:[~2019-07-19 16:14 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-17 17:21 [PATCH RFC v1] pidfd: fix a race in setting exit_state for pidfd polling Joel Fernandes (Google)
2019-07-17 17:55 ` Christian Brauner
2019-07-17 18:09 ` Suren Baghdasaryan
2019-07-17 20:47 ` Joel Fernandes
2019-07-18 10:09 ` Christian Brauner
2019-07-17 20:51 ` Joel Fernandes
2019-07-18 10:17 ` Christian Brauner
2019-07-18 16:05 ` Suren Baghdasaryan
2019-07-18 15:00 ` Oleg Nesterov
2019-07-19 16:14 ` Oleg Nesterov [this message]
2019-07-19 16:27 ` Christian Brauner
2019-07-19 16:33 ` Suren Baghdasaryan
2019-07-19 16:51 ` Joel Fernandes
2019-07-19 16:53 ` Christian Brauner
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