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From: Miroslav Benes <mbenes@suse.cz>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>,
	jpoimboe@kernel.org, jikos@kernel.org,  joe.lawrence@redhat.com,
	live-patching@vger.kernel.org
Subject: Re: [PATCH] livepatch: Avoid hard lockup caused by klp_try_switch_task()
Date: Fri, 31 Jan 2025 14:06:38 +0100 (CET)	[thread overview]
Message-ID: <alpine.LSU.2.21.2501311405280.10231@pobox.suse.cz> (raw)
In-Reply-To: <CALOAHbCw5_ZxNuRkwzMqz7NFdnJWgt-n4R--oYiE+BtNGP_8aw@mail.gmail.com>

Hi,

> $ cat log | grep do_exit | wc -l
> 1061
> 
> It seems that there are simply too many threads executing do_exit() at
> the moment.
> 
> >
> > You might try to use printk_deferred() instead. Also you might need
> > to disable interrupts around the read_lock()/read_unlock() to
> > make sure that the console handling will be deferred after
> > the tasklist_lock gets released.
> >
> > Anyway, I am against this patch.
> 
> However, there is still a risk of triggering a hard lockup if a large
> number of tasks are involved.

And as Petr said, it is very likely caused by pr_debug() in this setup. 
The proposed patch is not a fix and would make things only worse.

Regards,
Miroslav

  reply	other threads:[~2025-01-31 13:06 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-01-22  8:51 [PATCH] livepatch: Avoid hard lockup caused by klp_try_switch_task() Yafang Shao
2025-01-22 12:50 ` Petr Mladek
2025-01-22 13:46   ` Yafang Shao
2025-01-31 13:06     ` Miroslav Benes [this message]
2025-01-31 13:22   ` zhang warden
2025-01-31 13:39     ` Petr Mladek
2025-02-01  2:04       ` zhang warden
2025-02-05  8:39       ` Yafang Shao
2025-02-06 16:43         ` Petr Mladek
2025-02-07  2:16           ` Yafang Shao

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