linux-kernel - Re: [PATCH] release_task: kill the no longer needed get/put_pid(thread

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Message-ID: <20250414203955.GH28345@redhat.com>
Date: Mon, 14 Apr 2025 22:39:56 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Christian Brauner <brauner@...nel.org>
Cc: Mateusz Guzik <mjguzik@...il.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] release_task: kill the no longer needed
 get/put_pid(thread_pid)

On 04/14, Christian Brauner wrote:
>
> On Mon, Apr 14, 2025 at 09:39:47PM +0200, Christian Brauner wrote:
> > On Fri, Apr 11, 2025 at 02:18:57PM +0200, Oleg Nesterov wrote:
> > > -	put_pid(thread_pid);
> > > +	/* p->thread_pid can't go away until free_pids() below */
> > > +	proc_flush_pid(p->thread_pid);
> >
> > This cannot work though, right?
> > Because after __unhash_process() p->thread_pid may be NULL:

Oh, indeed! What was I thinking about???

And, as you can guess, I didn't even bother to test this "obvious" cleanup :/

> The task_pid() needs to be moved after the repeat label. I'm appending
> the full patch I applied.

Thanks a lot!

Can you add your Co-developed-by or Fixed-by ?

Oleg.