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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Derek Barbosa <debarbos@redhat.com>
Cc: pmladek@suse.com, rostedt@goodmis.org, john.ogness@linutronix.de,
	senozhatsky@chromium.org, linux-rt-users@vger.kernel.org,
	linux-kernel@vger.kernel.org, williams@redhat.com,
	jlelli@redhat.com, ahalaney@redhat.com, lgoncalv@redhat.com,
	jwyatt@redhat.com, aubaker@redhat.com
Subject: Re: [BUG] printk/nbcon.c: watchdog BUG: softlockup - CPU#x stuck for
 78s
Message-ID: <20240620093246.HE9XDWSZ@linutronix.de>
References: <ZnHF5j1DUDjN1kkq@debarbos-thinkpadt14sgen2i.remote.csb>
 <20240620071545.Es9LoyJY@linutronix.de>
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In-Reply-To: <20240620071545.Es9LoyJY@linutronix.de>

On 2024-06-20 09:15:45 [+0200], To Derek Barbosa wrote:
> On 2024-06-18 13:37:42 [-0400], Derek Barbosa wrote:
> > Hi,
> Hi,
> 
> > We have a modicum of reasonable suspicion to believe that nbcon_reacquire, or
> > some other nbcon mechanism *may* be causing such behavior.
> 
> Does this help?
> 
> diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
> index bb9689f94d302..0813ce88a49c5 100644
> --- a/kernel/printk/nbcon.c
> +++ b/kernel/printk/nbcon.c
> @@ -1119,6 +1119,7 @@ static int nbcon_kthread_func(void *__console)
>  		}
>  
>  		console_srcu_read_unlock(cookie);
> +		cond_resched();
>  
>  	} while (backlog);
>  

Okay. Works here on a 144 CPU box without CONFIG_PREEMPT.

Sebastian