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From: Petr Mladek <pmladek@suse.com>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: John Ogness <john.ogness@linutronix.de>,
	Sergey Senozhatsky <senozhatsky@chromium.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	frederic@kernel.org, Peter Geis <pgwipeout@gmail.com>,
	zhouzhouyi@gmail.com, dave@stgolabs.net, josh@joshtriplett.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	rcu@vger.kernel.org, linux-rockchip@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/2] printk: Prevent printk kthreads from blocking direct console handling
Date: Wed, 15 Jun 2022 22:09:17 +0200	[thread overview]
Message-ID: <Yqo8bbp10BFqNmiD@alley> (raw)
In-Reply-To: <20220615171042.GT1790663@paulmck-ThinkPad-P17-Gen-1>

On Wed 2022-06-15 10:10:42, Paul E. McKenney wrote:
> On Wed, Jun 15, 2022 at 06:28:03PM +0200, Petr Mladek wrote:
> > There are reports that console kthreads prevented printing
> > messages during panic() or shutdown(), see
> > BugLink: https://lore.kernel.org/r/20220610205038.GA3050413@paulmck-ThinkPad-P17-Gen-1
> > BugLink: https://lore.kernel.org/r/CAMdYzYpF4FNTBPZsEFeWRuEwSies36QM_As8osPWZSr2q-viEA@mail.gmail.com
> > 
> > In both situations, printk() correctly tries to flush the consoles
> > directly but it fails to get the global console_lock(). Both
> > problems went away with these patches:
> > 
> > 1st patch blocks console kthreads so that they do not start
> > handling new messages when the direct printing is preferred
> > by the system state. It is probably enough on its own. It
> > solves the problem when the kthreads actively did
> > the wrong thing.
> > 
> > 2nd patch allows to wait for the console kthreads to release
> > the lock in any context. It should make it more reliable.
> > It would have been useful even for the legacy code.
> 
> Thank you!
> 
> For the series:
> 
> Tested-by: Paul E. McKenney <paulmck@kernel.org>

Thanks a lot for testing.

I have pushed it into printk/linux.git, branch rework/kthreads
to give it a spin in linux-next.

Best Regards,
Petr

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      reply	other threads:[~2022-06-15 20:09 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-15 16:28 [PATCH 0/2] printk: Prevent printk kthreads from blocking direct console handling Petr Mladek
2022-06-15 16:28 ` [PATCH 1/2] printk: Block console kthreads when direct printing will be required Petr Mladek
2022-06-15 17:47   ` Linus Torvalds
2022-06-15 19:20     ` Petr Mladek
2022-06-15 16:28 ` [PATCH 2/2] printk: Wait for the global console lock when the system is going down Petr Mladek
2022-06-15 17:10 ` [PATCH 0/2] printk: Prevent printk kthreads from blocking direct console handling Paul E. McKenney
2022-06-15 20:09   ` Petr Mladek [this message]

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