linux-kernel - Re: [resend][bug] low-probability console lockups since 5.19

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Message-ID: <877d1m46c0.fsf@jogness.linutronix.de>
Date:   Thu, 29 Sep 2022 16:19:03 +0206
From:   John Ogness <john.ogness@...utronix.de>
To:     Conor Dooley <conor.dooley@...rochip.com>,
        Petr Mladek <pmladek@...e.com>
Cc:     Thorsten Leemhuis <regressions@...mhuis.info>,
        Conor Dooley <conor@...nel.org>, senozhatsky@...omium.org,
        rostedt@...dmis.org, linux-kernel@...r.kernel.org,
        regressions@...ts.linux.dev
Subject: Re: [resend][bug] low-probability console lockups since 5.19

On 2022-09-29, Conor Dooley <conor.dooley@...rochip.com> wrote:
> I will, possibly tonight but probably not, run the bisection again
> with the threaded printer merge reverted. Hopefully it is not filled
> with conflicts if I go that way...

It might be easier for you to just apply the following patch to run your
tests . This simple patch disables kthread usage.

John Ogness


diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index b095fb5f5f61..9679887c0805 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3605,6 +3605,10 @@ static int __init printk_activate_kthreads(void)
 {
 	struct console *con;
 
+	/* hack: never activate kthreads */
+	if (!printk_kthreads_available)
+		return 0;
+
 	console_lock();
 	printk_kthreads_available = true;
 	for_each_console(con)