Re: [PATCH] watchdog: ignore nohz_full cores in new cpumask

[Zqiang]

On 2021/11/15 下午11:31, Petr Mladek wrote:
> On Fri 2021-11-12 13:14:34, Zqiang wrote:
> > If the nohz_full is enabled, when update watchdog_mask, the
> > nohz_full cores should be ignored.
> >
> > Signed-off-by: Zqiang <qiang.zhang1211@xxxxxxxxx>
> > ---
> >   kernel/watchdog.c | 4 +++-
> >   1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel/watchdog.c b/kernel/watchdog.c
> > index ad912511a0c0..3ef11a94783c 100644
> > --- a/kernel/watchdog.c
> > +++ b/kernel/watchdog.c
> > @@ -628,7 +628,9 @@ void lockup_detector_soft_poweroff(void)
> >   static void proc_watchdog_update(void)
> >   {
> >   	/* Remove impossible cpus to keep sysctl output clean. */
> > -	cpumask_and(&watchdog_cpumask, &watchdog_cpumask, cpu_possible_mask);
> > +	cpumask_and(&watchdog_cpumask, &watchdog_cpumask,
> > housekeeping_cpumask(HK_FLAG_TIMER));
> I am not familiar with nozh_full code but this looks fine.
>
>
> > +	if (cpumask_empty(&watchdog_cpumask))
> > +		return;
> But this looks looks wrong. Is there any reason for this?
>
> We need to stop the watchdog when it was running before.
>
> I mean that lockup_detector_reconfigure() must be called anytime
> when the mask has changed even when it became empty.

Thanks Petr

I will resend patch v2.

> >   	lockup_detector_reconfigure();
> >   }
> Best Regards,
> Petr