linux-kernel - Re: [PATCH 1/4] workqueue: Reap workers via kthread_stop() and remove detach

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Message-ID: <CAJhGHyAkGHAje0z89tW-NaXT_u7xgL_CT-4jJKRZn=XcNjLgKQ@mail.gmail.com>
Date: Mon, 29 Jul 2024 09:49:31 +0800
From: Lai Jiangshan <jiangshanlai@...il.com>
To: Marc Hartmayer <mhartmay@...ux.ibm.com>
Cc: linux-kernel@...r.kernel.org, Lai Jiangshan <jiangshan.ljs@...group.com>, 
	Valentin Schneider <vschneid@...hat.com>, Tejun Heo <tj@...nel.org>, Heiko Carstens <hca@...ux.ibm.com>, 
	Sven Schnelle <svens@...ux.ibm.com>, Mete Durlu <meted@...ux.ibm.com>
Subject: Re: [PATCH 1/4] workqueue: Reap workers via kthread_stop() and remove detach_completion

Hello Marc

On Thu, Jul 25, 2024 at 8:11 AM Lai Jiangshan <jiangshanlai@...il.com> wrote:
> > 2024/07/23 18:01:21 [M83LP63]: [  157.267727] ------------[ cut here ]------------
> > 2024/07/23 18:01:21 [M83LP63]: [  157.267735] WARNING: CPU: 21 PID: 725 at kernel/workqueue.c:3340 worker_thread+0x54e/0x558
>
>
> > @@ -3330,7 +3338,6 @@ static int worker_thread(void *__worker)
> >                 ida_free(&pool->worker_ida, worker->id);
> >                 worker_detach_from_pool(worker);
> >                 WARN_ON_ONCE(!list_empty(&worker->entry));
> > -               kfree(worker);
> >                 return 0;
> >         }
>
> The condition "!list_empty(&worker->entry)" can be true when the
> worker is still in the cull_list awaiting being reaped by
> reap_dying_workers() after
> this change.
>
> I will remove the WARN_ON_ONCE().
>

Here is the fix:
https://lore.kernel.org/lkml/20240725010437.694727-1-jiangshanlai@gmail.com/

Could you take a look please.

Thank you for the report,
Lai