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Fri, 09 Oct 2026 08:27:07 -0700 (PDT) Date: Fri, 9 Oct 2026 17:27:04 +0200 From: Petr Mladek To: John Ogness Cc: Sebastian Andrzej Siewior , Sergey Senozhatsky , Steven Rostedt , Pavel Tikhomirov , Oleg Nesterov , Christian Brauner , oe-lkp@lists.linux.dev, lkp@intel.com, linux-serial@vger.kernel.org, oliver.sang@intel.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] nbcon/reboot: Flush nbcon consoles synchronously on reboot Message-ID: References: <20261008150852.8286-1-pmladek@suse.com> <20261009065152.udyfFRHx@linutronix.de> <87qzhzxatd.fsf@jogness.linutronix.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87qzhzxatd.fsf@jogness.linutronix.de> On Fri 2026-10-09 15:34:30, John Ogness wrote: > On 2026-10-09, Petr Mladek wrote: > > Anyway, IMHO, we should switch to NBCON_PRIO_EMERGENCY for the post-running > > states and flush the pending messages immediately. It is more > > reliable. It is easy to find the locations when system_state() is set. > > And all follow-up printk() calls will try the direct flush so that > > they won't rely on an explicit flush. > > We need to be careful about abusing CPU state in order to get certain > functionality. We already have things in place to gracefully switch to > atomic after shutting down the printing kthreads. This explains why I see the messages even without this patch. I wonder what is actually going on in the test. The log contains: LKP: ttyS0: 256: LKP: tbox cant kexec and rebooting forcely I see this message in lkp-tests/bin/lkp-setup-rootfs: lkp_reboot() { local tbox_state="rebooting" [ -n "$1" ] && tbox_state="rebooting_$1" set_tbox_wtmp $tbox_state # Avoid get stuck in yocto minimal rootfs. # LKP: rebooting # [ 8.124081] LKP: rebooting # # (shell prompt) is_virt && [ -e '/proc/sysrq-trigger' ] && { sync echo s >/proc/sysrq-trigger echo b >/proc/sysrq-trigger } start_reboot_watchdog reboot_tbox 2>/dev/null exit } [...] if tbox_cant_kexec; then echo_to_tty "LKP: tbox cant kexec and rebooting forcely" lkp_reboot "cant_kexec" fi so, it ends with reboot_tbox which is: reboot_tbox() { reboot } BUG: kernel reboot-without-warning in test stage I might need to try reproducing it with the lkp-test framework. But it has to wait for the next week. Best Regards, Petr