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Date: Mon, 11 Mar 2024 17:08:08 +0000
From: Catalin Marinas <catalin.marinas@arm.com>
To: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	"Christoph Lameter (Ampere)" <cl@linux.com>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Viresh Kumar <vireshk@kernel.org>, Will Deacon <will@kernel.org>,
	Jonathan.Cameron@huawei.com, Matteo.Carlini@arm.com,
	Valentin.Schneider@arm.com, akpm@linux-foundation.org,
	anshuman.khandual@arm.com, Eric Mackay <eric.mackay@oracle.com>,
	dave.kleikamp@oracle.com, linux-arm-kernel@lists.infradead.org,
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	linux@armlinux.org.uk, robin.murphy@arm.com,
	vanshikonda@os.amperecomputing.com, yang@os.amperecomputing.com,
	Nishanth Menon <nm@ti.com>, Stephen Boyd <sboyd@kernel.org>
Subject: Re: [PATCH v3] ARM64: Dynamically allocate cpumasks and increase
 supported CPUs to 512
Message-ID: <Ze86eH-RDIanc4Ac@arm.com>
References: <37099a57-b655-3b3a-56d0-5f7fbd49d7db@gentwo.org>
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 <e3952dc0-ec28-e7c7-e858-c47f146c93de@linux.com>
 <Ze71H4AdY786nSvn@FVFF77S0Q05N>
 <8abb1a69-6cbd-4a36-ab1d-d269cdafa391@samsung.com>
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In-Reply-To: <8c8aea4d-e911-44cd-bbec-ead4e44d338a@samsung.com>

On Mon, Mar 11, 2024 at 05:51:04PM +0100, Marek Szyprowski wrote:
> On 11.03.2024 16:22, Catalin Marinas wrote:
> > On Mon, Mar 11, 2024 at 03:56:37PM +0100, Marek Szyprowski wrote:
> >> On 11.03.2024 13:12, Mark Rutland wrote:
> >>> On Fri, Mar 08, 2024 at 09:08:59AM -0800, Christoph Lameter (Ampere) wrote:
> >>>> On Fri, 8 Mar 2024, Marek Szyprowski wrote:
> >>>>>>> It looks that cpufreq-dt and/or opp drivers needs some adjustments
> >>>>>>> related with this change.
> >>>>>> That's strange. Is this with defconfig? I wonder whether NR_CPUS being
> >>>>>> larger caused the issue with this specific code. Otherwise
> >>>>>> CPUMASK_OFFSTACK may not work that well on arm64.
> >>>> cpumask handling must use the accessor functions provided in
> >>>> include/linux/cpumask.h for declaring and accessing cpumasks. It is likely
> >>>> related to the driver opencoding one of the accessors.
> >>> I took a look at both the OPP code and the cpufreq-dt code and it looks like
> >>> those are doign the right thing w.r.t. cpumask manipulation (i.e. they only use
> >>> the cpumask accessors, and use the cpumask_var_*() functions to dynamically
> >>> allocate/free cpumasks). Maybe I've missed something, but superficially those
> >>> look right.
> >>>
> >>> Marek, can you try reverting this commit and trying defconfig + NR_CPUS=512?
> >> Yes, with $subject reverted and CONFIG_NR_CPUS=512 everything works
> >> fine, so it must be something else broken.
> > Thanks for confirming. Would you mind testing the problematic commit
> > with CONFIG_DEBUG_PER_CPU_MAPS enabled? If it doesn't show anything
> > obvious that can be fixed quickly, I'll revert the commit and queue it
> > again after -rc1 for 6.10 (I haven't sent 6.9 the pull request yet).
> 
> I've enabled this option, but unfortunately it didn't reveal anything 
> more besides the warning and error I've posted in my initial report. I 
> will try to analyze this issue further, but I won't manage to do this today.

No worries, thanks for giving this a try.

-- 
Catalin