Re: [PATCH v11 4/6] arm64: smp: Add arch support for backtrace using pseudo-NMI

From: Doug Anderson <dianders@chromium.org>
To: "Tomohiro Misono (Fujitsu)" <misono.tomohiro@fujitsu.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Sumit Garg <sumit.garg@linaro.org>,
	Daniel Thompson <daniel.thompson@linaro.org>,
	Marc Zyngier <maz@kernel.org>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"kgdb-bugreport@lists.sourceforge.net" 
	<kgdb-bugreport@lists.sourceforge.net>,
	Lecopzer Chen <lecopzer.chen@mediatek.com>,
	"linux-perf-users@vger.kernel.org"
	<linux-perf-users@vger.kernel.org>,
	Masayoshi Mizuma <msys.mizuma@gmail.com>,
	Chen-Yu Tsai <wens@csie.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"Yuichi Ito (Fujitsu)" <ito-yuichi@fujitsu.com>,
	Stephen Boyd <swboyd@chromium.org>,
	Peter Zijlstra <peterz@infradead.org>,
	D Scott Phillips <scott@os.amperecomputing.com>,
	Ingo Molnar <mingo@kernel.org>,
	Josh Poimboeuf <jpoimboe@kernel.org>,
	Valentin Schneider <vschneid@redhat.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v11 4/6] arm64: smp: Add arch support for backtrace using pseudo-NMI
Date: Tue, 29 Aug 2023 09:03:04 -0700	[thread overview]
Message-ID: <CAD=FV=UZeHicVLn3GAxdFrtUbwHnb8GEvsfe9BM7cfBrTrK=Fg@mail.gmail.com> (raw)
In-Reply-To: <TYCPR01MB11025E1AB8ED779D1D67F05CBE5E7A@TYCPR01MB11025.jpnprd01.prod.outlook.com>

Hi,

On Mon, Aug 28, 2023 at 10:23 PM Tomohiro Misono (Fujitsu)
<misono.tomohiro@fujitsu.com> wrote:
>
> > -----Original Message-----
> > Subject: [PATCH v11 4/6] arm64: smp: Add arch support for backtrace using
> > pseudo-NMI
> >
> > Enable arch_trigger_cpumask_backtrace() support on arm64. This enables
> > things much like they are enabled on arm32 (including some of the
> > funky logic around NR_IPI, nr_ipi, and MAX_IPI) but with the
> > difference that, unlike arm32, we'll try to enable the backtrace to
> > use pseudo-NMI.
> >
> > NOTE: this patch is a squash of the little bit of code adding the
> > ability to mark an IPI to try to use pseudo-NMI plus the little bit of
> > code to hook things up for kgdb. This approach was decided upon in the
> > discussion of v9 [1].
> >
> > This patch depends on commit 36759e343ff9 ("nmi_backtrace: allow
>
> Hi,
> Is this commit ID valid? I believe this commit is not included in the
> mainline yet. Other than this,
>  Reviewed-by: Misono Tomohiro <misono.tomohiro@fujitsu.com>

Ah, good call. I must have grabbed that git hash before the commit
moved from Andrew Morton's unstable branch to his stable branch. As
far as I can tell, it should be commit 8d539b84f1e3 ("nmi_backtrace:
allow excluding an arbitrary CPU"). ...at least that's what's in
linuxnext today. That also appears to match the commit hash in the
pull request that Andrew just sent to Linus [1].

I'll update the git hash and add your tag in v12, which I'm currently
aiming to send out tomorrow.

[1] https://lore.kernel.org/r/20230828225431.354d3d2d3b80ee5b88e65eb5@linux-foundation.org