From: Mikulas Patocka <mpatocka@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>,
Mike Snitzer <msnitzer@redhat.com>, Jens Axboe <axboe@kernel.dk>,
Damien Le Moal <dlemoal@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Waiman Long <longman@redhat.com>,
Guangwu Zhang <guazhang@redhat.com>,
dm-devel@lists.linux.dev, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] completion: move blk_wait_io to kernel/sched/completion.c
Date: Tue, 23 Apr 2024 14:36:45 +0200 (CEST) [thread overview]
Message-ID: <8ab5c16e-154-c66-d167-5ce9eb6ea331@redhat.com> (raw)
In-Reply-To: <20240422105956.GN30852@noisy.programming.kicks-ass.net>
On Mon, 22 Apr 2024, Peter Zijlstra wrote:
> On Wed, Apr 17, 2024 at 09:57:04PM -0700, Christoph Hellwig wrote:
> > On Wed, Apr 17, 2024 at 08:00:22PM +0200, Mikulas Patocka wrote:
> > > > > +EXPORT_SYMBOL(wait_for_completion_long_io);
> > > >
> > > > Urgh, why is it a sane thing to circumvent the hang check timer?
> > >
> > > The block layer already does it - the bios can have arbitrary size, so
> > > waiting for them takes arbitrary time.
> >
> > And as mentioned the last few times around, I think we want a task
> > state to say that task can sleep long or even forever and not propagate
> > this hack even further.
>
> A bit like TASK_NOLOAD (which is used to make TASK_IDLE work), but
> different I suppose.
>
> TASK_NOHUNG would be trivial to add ofc. But is it worth it?
>
> Anyway, as per the other email, anything like this needs to come with a
> big fat warning. You get to keep the pieces etc..
This seems better than the blk_wait_io hack.
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
> ---
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 3c2abbc587b4..83b25327c233 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -112,7 +112,8 @@ struct user_event_mm;
> #define TASK_FREEZABLE 0x00002000
> #define __TASK_FREEZABLE_UNSAFE (0x00004000 * IS_ENABLED(CONFIG_LOCKDEP))
> #define TASK_FROZEN 0x00008000
> -#define TASK_STATE_MAX 0x00010000
> +#define TASK_NOHUNG 0x00010000
> +#define TASK_STATE_MAX 0x00020000
>
> #define TASK_ANY (TASK_STATE_MAX-1)
>
> diff --git a/kernel/hung_task.c b/kernel/hung_task.c
> index b2fc2727d654..126fac835e5e 100644
> --- a/kernel/hung_task.c
> +++ b/kernel/hung_task.c
> @@ -210,7 +210,8 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
> state = READ_ONCE(t->__state);
> if ((state & TASK_UNINTERRUPTIBLE) &&
> !(state & TASK_WAKEKILL) &&
> - !(state & TASK_NOLOAD))
> + !(state & TASK_NOLOAD) &&
> + !(state & TASK_NOHUNG))
> check_hung_task(t, timeout);
> }
> unlock:
>
next prev parent reply other threads:[~2024-04-23 12:36 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-17 17:49 [PATCH 1/2] completion: move blk_wait_io to kernel/sched/completion.c Mikulas Patocka
2024-04-17 17:55 ` Peter Zijlstra
2024-04-17 18:00 ` Mikulas Patocka
2024-04-18 4:57 ` Christoph Hellwig
2024-04-18 14:30 ` Jens Axboe
2024-04-18 14:46 ` Christoph Hellwig
2024-04-18 15:09 ` Jens Axboe
2024-04-22 10:59 ` Peter Zijlstra
2024-04-23 12:36 ` Mikulas Patocka [this message]
2024-04-26 6:06 ` Christoph Hellwig
2024-04-22 10:54 ` Peter Zijlstra
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