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

From: Sumit Garg <sumit.garg@linaro.org>
To: Will Deacon <will@kernel.org>
Cc: Alexandru Elisei <alexandru.elisei@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	 Daniel Thompson <daniel.thompson@linaro.org>,
	Douglas Anderson <dianders@chromium.org>,
	 Lecopzer Chen <lecopzer@gmail.com>,
	Lecopzer Chen <lecopzer.chen@mediatek.com>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	 Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	 Stephen Boyd <swboyd@chromium.org>,
	yj.chiang@mediatek.com
Subject: Re: [PATCH v5] arm64: Enable perf events based hard lockup detector
Date: Mon, 12 Apr 2021 17:31:13 +0530	[thread overview]
Message-ID: <CAFA6WYPXu8biPPim5EoQ1pi+w3APKm65tzfOvH4OSORZdJ6+8Q@mail.gmail.com> (raw)
In-Reply-To: <CAFA6WYMqLMEG2s7OdNweQKkP0K2LZ575B1BVw-zfsg7_KBSM5Q@mail.gmail.com>

Hi Will,

On Tue, 30 Mar 2021 at 18:00, Sumit Garg <sumit.garg@linaro.org> wrote:
>
> On Tue, 30 Mar 2021 at 14:07, Lecopzer Chen <lecopzer.chen@mediatek.com> wrote:
> >
> > > > Hi Will, Mark,
> > > >
> > > > On Fri, 15 Jan 2021 at 17:32, Sumit Garg <sumit.garg@linaro.org> 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@linaro.org>
> > > > > ---
> > > > >
> > > > > 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?
> > > >

Since there aren't any further comments, can you re-pick this feature for 5.13?

-Sumit

> > > > 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

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