The CPU trigger is invoked on ARM from CPU-idle. That trigger later invokes led_trigger_event() which may invoke the callback of the actual driver. That driver can acquire a spinlock_t which is okay on kernel without PREEMPT_RT. On a PREEMPT_RT enabled kernel this lock is turned into a sleeping lock and must not be acquired with disabled interrupts. Disable the CPU trigger on PREEMPT_RT. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20210924111501.m57cwwn7ahiyxxdd@xxxxxxxxxxxxx --- v1…v2: Reword commit message now that read lock has been removed. drivers/leds/trigger/Kconfig | 1 + 1 file changed, 1 insertion(+) --- a/drivers/leds/trigger/Kconfig +++ b/drivers/leds/trigger/Kconfig @@ -64,6 +64,7 @@ config LEDS_TRIGGER_BACKLIGHT config LEDS_TRIGGER_CPU bool "LED CPU Trigger" + depends on !PREEMPT_RT help This allows LEDs to be controlled by active CPUs. This shows the active CPUs across an array of LEDs so you can see which
