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From: John Ogness <john.ogness@linutronix.de>
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To: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>, Steven Rostedt
 <rostedt@goodmis.org>, Pavel Tikhomirov <ptikhomirov@virtuozzo.com>, Oleg
 Nesterov <oleg@redhat.com>, Christian Brauner <brauner@kernel.org>,
 Sebastian Andrzej Siewior <bigeasy@linutronix.de>, oe-lkp@lists.linux.dev,
 lkp@intel.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
 Petr Mladek <pmladek@suse.com>
Subject: Re: [PATCH v2] nbcon/reboot: Switch NBCON consoles into the
 emergency mode in emergency_restart()
In-Reply-To: <20261013154141.94016-1-pmladek@suse.com>
References: <20261013154141.94016-1-pmladek@suse.com>
Date: Tue, 13 Oct 2026 18:15:19 +0206
Message-ID: <87y0c1vaz4.fsf@jogness.linutronix.de>
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On 2026-10-13, Petr Mladek <pmladek@suse.com> wrote:
> When the system is going down a normal way, the NBCON kthreads are
> flushed and stopped properly via a syscore shutdown callback, see
> printk_kthreads_shutdown().
>
> One missing piece is emergency_restart() where the kthreads are not
> stopped. It might be called from several non-panic code paths,
> e.g. sysrq-o, kdb_reboot(), or some watchdogs.
>
> Fix it by explicitly entering the emergency (atomic) mode and trying
> to flush the consoles there.
>
> Note that printk_trigger_flush() must be used instead of pr_flush()
> because the later is not safe in an atomic context.
>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/all/202608061008.48a1e76e-lkp@intel.com/
> Suggested-by: John Ogness <john.ogness@linutronix.de>
> Signed-off-by: Petr Mladek <pmladek@suse.com>

Reviewed-by: John Ogness <john.ogness@linutronix.de>

Thanks, Petr.