Re: [PATCH v2 2/2] mm: initialize deferred pages with interrupts enabled

From: Michal Hocko
Date: Thu Apr 02 2020 - 13:16:37 EST


On Thu 02-04-20 11:13:49, Pavel Tatashin wrote:
> > > I do wonder if this change is strictly required in this patch (IOW, if
> > > we could keep calling touch_nmi_watchdog() also without holding a spinlock)
> >
> > Exactly. I would go with your patch on top.
> >
> > > Anyhow, it's the right thing to do.
>
> Michal,
>
> The reason I changed it here is because in the original patch that
> this patch fixes we changed cond_sched() to touch_nmi_watchdog():
> $ git show 3a2d7fa8a3d5 | grep -E '(nmi|sched)'
> - cond_resched();
> + touch_nmi_watchdog();
> - cond_resched();
> + touch_nmi_watchdog();
>
> So, should I move it to a separate patch or is it OK to keep it here?

Having in a separate patch would be better IMO. If for nothing else, the
RCU stall would be easier to see.
--
Michal Hocko
SUSE Labs