On Thu, 8 Nov 2018 21:05:03 +0800 Feng Tang <[email protected]> wrote:
> Sometimes when debugging kernel panic, we saw many extra noisy error
> messages after the expected end:
>
> [ 35.743249] ---[ end Kernel panic - not syncing: Fatal exception
> [ 35.749975] ------------[ cut here ]------------
What are these "noisy messages"? The above looks OK?
> When panic happens under console mode, the screen will first show the panic
> call stack, but will immediately be overrided by noisy extra messages, like
> this for every CPU except the panic one:
>
> WARNING: CPU: 1 PID: 280 at kernel/sched/core.c:1198
> set_task_cpu+0x183/0x190
> Call Trace:
> <IRQ>
> try_to_wake_up
> default_wake_function
> autoremove_wake_function
> __wake_up_common
> __wake_up_common_lock
> __wake_up
> wake_up_klogd_work_func
> irq_work_run_list
> irq_work_tick
> update_process_times
> tick_sched_timer
> __hrtimer_run_queues
> hrtimer_interrupt
> smp_apic_timer_interrupt
> apic_timer_interrupt
And this output looks OK as well.
> Which make debugging more difficult, as the original context is
> lost on screen.
>
> Keeping the CPU IRQ disabled will void these messages, as we code
> run to this point, the user has chosed not to reboot, nor do
> some extra handling with panic notifier, not much point in
> re-enabling the interrupt.
And please have another attempt at the above paragraph?
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -295,7 +295,6 @@ void panic(const char *fmt, ...)
> }
> #endif
> pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
> - local_irq_enable();
> for (i = 0; ; i += PANIC_TIMER_STEP) {
> touch_softlockup_watchdog();
> if (i >= i_next) {
The patch looks reasonable, but the description is just too hard for me
to follow, sorry. Please spend a bit more time over that and resend?
