linux-kernel - Re: [BUG] printk/nbcon.c: watchdog BUG: softlockup

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Message-ID: <20240620071545.Es9LoyJY@linutronix.de>
Date: Thu, 20 Jun 2024 09:15:45 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Derek Barbosa <debarbos@...hat.com>
Cc: pmladek@...e.com, rostedt@...dmis.org, john.ogness@...utronix.de,
	senozhatsky@...omium.org, linux-rt-users@...r.kernel.org,
	linux-kernel@...r.kernel.org, williams@...hat.com,
	jlelli@...hat.com, ahalaney@...hat.com, lgoncalv@...hat.com,
	jwyatt@...hat.com, aubaker@...hat.com
Subject: Re: [BUG] printk/nbcon.c: watchdog BUG: softlockup - CPU#x stuck for
 78s

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);
 

Sebastian