Re: [PATCH v5 15/18] watchdog/perf: Add a weak function for an arch to detect if perf can use NMIs

From: Mark Rutland <mark.rutland@arm.com>
To: Doug Anderson <dianders@chromium.org>
Cc: Petr Mladek <pmladek@suse.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Matthias Kaehlcke <mka@chromium.org>,
	kgdb-bugreport@lists.sourceforge.net,
	Stephane Eranian <eranian@google.com>,
	mpe@ellerman.id.au, Tzung-Bi Shih <tzungbi@chromium.org>,
	Daniel Thompson <daniel.thompson@linaro.org>,
	linuxppc-dev@lists.ozlabs.org, Sumit Garg <sumit.garg@linaro.org>,
	npiggin@gmail.com, davem@davemloft.net,
	Marc Zyngier <maz@kernel.org>, Stephen Boyd <swboyd@chromium.org>,
	sparclinux@vger.kernel.org, christophe.leroy@csgroup.eu,
	Catalin Marinas <catalin.marinas@arm.com>,
	ravi.v.shankar@intel.com, Randy Dunlap <rdunlap@infradead.org>,
	Pingfan Liu <kernelfans@gmail.com>,
	Guenter Roeck <groeck@chromium.org>,
	Lecopzer Chen <lecopzer.chen@mediatek.com>,
	Ian Rogers <irogers@google.com>,
	ito-yuichi@fujitsu.com, ricardo.neri@intel.com,
	linux-arm-kernel@lists.infradead.org,
	linux-perf-users@vger.kernel.org, Will Deacon <will@kernel.org>,
	Chen-Yu Tsai <wens@csie.org>,
	linux-kernel@vger.kernel.org,
	Masayoshi Mizuma <msys.mizuma@gmail.com>,
	Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH v5 15/18] watchdog/perf: Add a weak function for an arch to detect if perf can use NMIs
Date: Mon, 12 Jun 2023 14:59:13 +0100	[thread overview]
Message-ID: <ZIckscgmirrgxZ75@FVFF77S0Q05N> (raw)
In-Reply-To: <CAD=FV=WyLKygSsArCaSzid47Rz5=ozR6Yh9L6Q3JStpzF9Tn9w@mail.gmail.com>

On Mon, Jun 12, 2023 at 06:55:37AM -0700, Doug Anderson wrote:
> Mark,
> 
> On Mon, Jun 12, 2023 at 3:33 AM Mark Rutland <mark.rutland@arm.com> wrote:
> >
> > On Fri, May 19, 2023 at 10:18:39AM -0700, Douglas Anderson wrote:
> > > On arm64, NMI support needs to be detected at runtime. Add a weak
> > > function to the perf hardlockup detector so that an architecture can
> > > implement it to detect whether NMIs are available.
> > >
> > > Signed-off-by: Douglas Anderson <dianders@chromium.org>
> > > ---
> > > While I won't object to this patch landing, I consider it part of the
> > > arm64 perf hardlockup effort. I would be OK with the earlier patches
> > > in the series landing and then not landing ${SUBJECT} patch nor
> > > anything else later.
> >
> > FWIW, everything prior to this looks fine to me, so I reckon it'd be worth
> > splitting the series here and getting the buddy lockup detector in first, to
> > avoid a log-jam on all the subsequent NMI bits.
> 
> I think the whole series has already landed in Andrew's tree,
> including the arm64 "perf" lockup detector bits. I saw all the
> notifications from Andrew go through over the weekend that they were
> moved from an "unstable" branch to a "stable" one and I see them at:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/log/?h=mm-nonmm-stable
> 
> When I first saw Anderw land the arm64 perf lockup detector bits in
> his unstable branch several weeks ago, I sent a private message to the
> arm64 maintainers (yourself included) to make sure you were aware of
> it and that it hadn't been caught in mail filters. I got the
> impression that everything was OK. Is that not the case?

Sorry; I'm slowly catching up with a backlog of email, and I'm just behind.

Feel free to ignore this; sorry for the noise!

If we spot anything going wrong in testing we can look at fixing those up.

Thanks,
Mark.