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

From: Doug Anderson <dianders@chromium.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Ian Rogers <irogers@google.com>,
	ito-yuichi@fujitsu.com,
	Lecopzer Chen <lecopzer.chen@mediatek.com>,
	ravi.v.shankar@intel.com,
	Catalin Marinas <catalin.marinas@arm.com>,
	ricardo.neri@intel.com, Stephane Eranian <eranian@google.com>,
	sparclinux@vger.kernel.org, Guenter Roeck <groeck@chromium.org>,
	Will Deacon <will@kernel.org>,
	Daniel Thompson <daniel.thompson@linaro.org>,
	Andi Kleen <ak@linux.intel.com>, Marc Zyngier <maz@kernel.org>,
	Chen-Yu Tsai <wens@csie.org>,
	Matthias Kaehlcke <mka@chromium.org>,
	kgdb-bugreport@lists.sourceforge.net,
	Masayoshi Mizuma <msys.mizuma@gmail.com>,
	Petr Mladek <pmladek@suse.com>,
	Tzung-Bi Shih <tzungbi@chromium.org>,
	npiggin@gmail.com, Stephen Boyd <swboyd@chromium.org>,
	Pingfan Liu <kernelfans@gmail.com>,
	linux-arm-kernel@lists.infradead.org,
	Sumit Garg <sumit.garg@linaro.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	linuxppc-dev@lists.ozlabs.o rg, davem@davemloft.net
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 06:55:37 -0700	[thread overview]
Message-ID: <CAD=FV=WyLKygSsArCaSzid47Rz5=ozR6Yh9L6Q3JStpzF9Tn9w@mail.gmail.com> (raw)
In-Reply-To: <ZIb0hd8djM+jJviF@FVFF77S0Q05N>

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?

-Doug