From: Benjamin Marzinski <bmarzins@redhat.com>
To: Joel Colledge <joel.colledge@linbit.com>
Cc: Christian Loehle <christian.loehle@arm.com>,
Mikulas Patocka <mpatocka@redhat.com>,
Alasdair Kergon <agk@redhat.com>,
Mike Snitzer <snitzer@kernel.org>,
dm-devel@lists.linux.dev
Subject: Re: [PATCH 1/1] dm-delay: fix hung task introduced by kthread mode
Date: Fri, 3 May 2024 18:56:58 -0400 [thread overview]
Message-ID: <ZjVrulz4zt77Lv6f@redhat.com> (raw)
In-Reply-To: <CAGNP_+WStY+C9=eT=gzC-dYhMtPTj4kzKDSuYiVHi0w41Qa_8w@mail.gmail.com>
On Tue, Apr 30, 2024 at 06:12:37PM +0200, Joel Colledge wrote:
> On Tue, 30 Apr 2024 at 17:27, Christian Loehle <christian.loehle@arm.com> wrote:
> > On 30/04/2024 15:44, Joel Colledge wrote:
> > > On Tue, 30 Apr 2024 at 16:28, Christian Loehle <christian.loehle@arm.com> wrote:
> > >> Is this an issue for delay > 0 too somehow?
> > >
> > > I believe it is. If there is simply no IO to the delay device, then
> > > nothing will wake the new thread and the same issue will occur.
> >
> > Yes, but might be better to just set_current_state(TASK_INTERRUPTIBLE);
> > instead of the wakeup.
>
> I'm afraid I don't follow what you mean.
> set_current_state(TASK_INTERRUPTIBLE) would need to be called from the
> worker, but the worker isn't running yet, so it can't do that.
>
> When preparing this patch, I checked how common kthread_create()
> followed by wake_up_process() is. It is fairly common according to
> this very approximate metric:
> $ grep -r -I -A10 kthread_create | grep -c wake_up_process
> 49
>
> I just looked through those matches in more detail and noticed that
> there is a kthread_run() macro which does exactly what we need. I will
> change my suggestion to use that instead.
>
> I will wait for more comments before sending a new version of the patch.
kthread_run() looks like the right solution here. There's no need to
wait for more initialization and the kthread will put itself to sleep
momentarily. Please send an updated patch.
-Ben
>
> Best regards,
> Joel
prev parent reply other threads:[~2024-05-03 22:57 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 7:21 [PATCH 0/1] dm-delay: fix hung task issue Joel Colledge
2024-04-26 7:21 ` [PATCH 1/1] dm-delay: fix hung task introduced by kthread mode Joel Colledge
2024-04-30 14:28 ` Christian Loehle
2024-04-30 14:44 ` Joel Colledge
2024-04-30 15:26 ` Christian Loehle
2024-04-30 16:12 ` Joel Colledge
2024-05-01 8:26 ` Christian Loehle
2024-05-03 22:56 ` Benjamin Marzinski [this message]
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