linux-kernel - Re: [PATCH v4] kthread_worker: Prevent queuing delayed work from timer

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Date:   Thu, 15 Oct 2020 14:38:15 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     akpm@...ux-foundation.org
Cc:     tj@...nel.org, hdanton@...a.com,
        Zqiang <qiang.zhang@...driver.com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH v4] kthread_worker: Prevent queuing delayed work from
 timer_fn when it is being canceled

On Wed 2020-10-14 15:50:48, Zqiang wrote:
> There is a small race window when a delayed work is being canceled and
> the work still might be queued from the timer_fn:
> 
> 	CPU0						CPU1
> kthread_cancel_delayed_work_sync()
>    __kthread_cancel_work_sync()
>      __kthread_cancel_work()
>         work->canceling++;
> 					      kthread_delayed_work_timer_fn()
> 						   kthread_insert_work();
> 
> BUG: kthread_insert_work() should not get called when work->canceling
> is set.
> 
> Cc: <stable@...r.kernel.org>
> Reviewed-by: Petr Mladek <pmladek@...e.com>
> Acked-by: Tejun Heo <tj@...nel.org>
> Signed-off-by: Zqiang <qiang.zhang@...driver.com>

Andrew, are you going to take this patch with -mm tree, please?

I think that you usually take the changes in kthread.c.

Best Regards,
Petr