Re: [PATCH v3] ARM64: Dynamically allocate cpumasks and increase supported CPUs to 512

[Catalin Marinas <catalin.marinas@arm.com>]

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).

-- 
Catalin