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From: Petr Mladek <pmladek@suse.com>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: john.ogness@linutronix.de, linux-kernel@vger.kernel.org,
	frederic@kernel.org
Subject: Re: [BUG] 8e274732115f ("printk: extend console_lock for per-console locking")
Date: Mon, 13 Jun 2022 12:50:31 +0200	[thread overview]
Message-ID: <YqcWd16LNnFPRJHg@alley> (raw)
In-Reply-To: <20220610205038.GA3050413@paulmck-ThinkPad-P17-Gen-1>

On Fri 2022-06-10 13:50:38, Paul E. McKenney wrote:
> Hello, John,
> 
> I have started getting rcutorture shutdown-time hangs when running
> against recent mainline, and bisected back to the 8e274732115f ("printk:
> extend console_lock for per-console locking") commit.  These hangs go
> away (or at least their probability drops dramatically) if I build with
> CONFIG_PREEMPTION=n -and- CONFIG_NO_HZ=y (not n!), at least assuming
> that I also boot with "nohz_full=0-N".

This means that the kthreads are probably more often sleeping with
con->lock when the pre-emtion is done by regular ticks.

We might want to wake them if we could call pr_flush().
But we could not do this in the generic panic() path.
It might cause deadlock when panic() is called from
scheduler code.

Pest Regards,
Petr

      parent reply	other threads:[~2022-06-13 11:50 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-10 20:50 [BUG] 8e274732115f ("printk: extend console_lock for per-console locking") Paul E. McKenney
2022-06-12 13:23 ` Paul E. McKenney
2022-06-12 16:03   ` John Ogness
2022-06-12 16:30     ` Paul E. McKenney
2022-06-13 11:01     ` Petr Mladek
2022-06-13  2:12 ` John Ogness
2022-06-13  4:29   ` Paul E. McKenney
2022-06-13  9:04     ` John Ogness
2022-06-13 10:32       ` Petr Mladek
2022-06-13 15:07         ` Petr Mladek
2022-06-13 15:51           ` Paul E. McKenney
2022-06-13 15:44       ` Paul E. McKenney
2022-06-13 10:50 ` Petr Mladek [this message]

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