Re: [PATCH] kernel/sysrq: reset watchdog on all CPUs while processing sysrq-w

From: Ingo Molnar
Date: Wed Jun 08 2016 - 09:13:32 EST



* Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> wrote:

> Lengthy output of sysrq-w may take a lot of time on slow serial console.
> Currently we reset NMI-watchdog on the current CPU to avoid softlockup.
> Sometimes this doesn't work since watchdog might trigger on the other
> CPU which is waiting for an IPI to proceed.
>
> Reset watchdog on all CPUs to prevent spurious softlockup messages.
>
> Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
> ---
> kernel/sched/core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 7f2cae4..c135eee 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -5134,7 +5134,7 @@ void show_state_filter(unsigned long state_filter)
> * reset the NMI-timeout, listing all files on a slow
> * console might take a lot of time:
> */
> - touch_nmi_watchdog();
> + touch_all_softlockup_watchdogs();

So don't we want both?

Thanks,

Ingo