Re: [PATCH v5] arm64: Enable perf events based hard lockup detector

[Sumit Garg]

On Tue, 30 Mar 2021 at 14:07, Lecopzer Chen <lecopzer.chen@xxxxxxxxxxxx> wrote:
>
> > > Hi Will, Mark,
> > >
> > > On Fri, 15 Jan 2021 at 17:32, Sumit Garg <sumit.garg@xxxxxxxxxx> wrote:
> > > >
> > > > With the recent feature added to enable perf events to use pseudo NMIs
> > > > as interrupts on platforms which support GICv3 or later, its now been
> > > > possible to enable hard lockup detector (or NMI watchdog) on arm64
> > > > platforms. So enable corresponding support.
> > > >
> > > > One thing to note here is that normally lockup detector is initialized
> > > > just after the early initcalls but PMU on arm64 comes up much later as
> > > > device_initcall(). So we need to re-initialize lockup detection once
> > > > PMU has been initialized.
> > > >
> > > > Signed-off-by: Sumit Garg <sumit.garg@xxxxxxxxxx>
> > > > ---
> > > >
> > > > Changes in v5:
> > > > - Fix lockup_detector_init() invocation to be rather invoked from CPU
> > > >   binded context as it makes heavy use of per-cpu variables and shouldn't
> > > >   be invoked from preemptible context.
> > > >
> > >
> > > Do you have any further comments on this?
> > >
> > > Lecopzer,
> > >
> > > Does this feature work fine for you now?
> >
> > This really fixes the warning, I have a real hardware for testing this now.

Thanks for the testing. I assume it as an implicit Tested-by.

> > but do we need to call lockup_detector_init() for each cpu?
> >
> > In init/main.c, it's only called by cpu 0 for once.
>
> Oh sorry, I just misread the code, please ignore previous mail.
>

No worries.

-Sumit

>
> BRs,
> Lecopzer