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From:   John Ogness <john.ogness@linutronix.de>
To:     Conor Dooley <conor.dooley@microchip.com>,
        Petr Mladek <pmladek@suse.com>
Cc:     Thorsten Leemhuis <regressions@leemhuis.info>,
        Conor Dooley <conor@kernel.org>, senozhatsky@chromium.org,
        rostedt@goodmis.org, linux-kernel@vger.kernel.org,
        regressions@lists.linux.dev
Subject: Re: [resend][bug] low-probability console lockups since 5.19
In-Reply-To: <YzV40LbMHcW1S/9O@wendy>
References: <Yy3dsSgpDnovBdEn@spud> <YzR8fzyjhggO+/tT@spud>
 <98f62903-3d6f-30b4-82ef-3b0460824907@leemhuis.info>
 <YzVlYaUPcRmlfE7c@wendy> <YzVvl+rv3iZS9vxk@alley> <YzV40LbMHcW1S/9O@wendy>
Date:   Thu, 29 Sep 2022 16:19:03 +0206
Message-ID: <877d1m46c0.fsf@jogness.linutronix.de>
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On 2022-09-29, Conor Dooley <conor.dooley@microchip.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)