On panic() from IRQ (for instance from the lockup detector) we will end up in an endless loop on -RT. Each time we invoke spin_trylock_irqsave() we will trigger the WARN_ON() in rt_mutex_trylock(). The WARN_ON() will stuff more data into the printk buffer than we can print on one iteration and so we never end the printing loop.
Signed-off-by: Sebastian Andrzej Siewior <[email protected]> --- drivers/tty/serial/8250/8250_port.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 5568d70eee0c..138b1b985063 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2850,9 +2850,9 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, serial8250_rpm_get(up); - if (port->sysrq) + if (port->sysrq || oops_in_progress) locked = 0; - else if (oops_in_progress || in_kdb_printk()) + else if (in_kdb_printk()) locked = spin_trylock_irqsave(&port->lock, flags); else spin_lock_irqsave(&port->lock, flags); -- 2.7.0
