From: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> As the consoles are written with preemption enabled in PREEMPT_RT, we must not have any task spinning waiting on them. Currently, the code that would make the task spin is #ifdef out when PREEMPT_RT is enabled, but why go through grabbing of the locks to see if an owner is set, when it never will be? Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> --- diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index a43d07d4e043..1a61132deec1 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -1742,6 +1742,13 @@ static int console_trylock_spinning(void) if (console_trylock()) return 1; + /* + * The consoles are preemptable in PREEMPT_RT, which can cause + * spinning to deadlock. + */ + if (IS_ENABLED(CONFIG_PREEMPT_RT_FULL)) + return 0; + printk_safe_enter_irqsave(flags); raw_spin_lock(&console_owner_lock);
