Re: [PATCH 0/4] ARM: allocate the cacheinfo early to fix the PREEMPT_RT boot warning

[Sebastian Andrzej Siewior]

On 2026-09-12 21:55:48 [+0200], Karl Mehltretter wrote:
> This series moves ARM cacheinfo allocation to the boot CPU to avoid
> sleeping-lock warnings during PREEMPT_RT secondary-CPU startup. It is
> based on 5225b8eec4c9 (7.3-rc2 plus one day).
> 
> Patches 1-3 prepare for early allocation: bound cache-leaf writes,
> include external caches in the allocation size, and guard CLIDR reads
> on older CPUs. Patch 4 enables early allocation. Please take all four
> patches together for stable.
> 
> Tested on QEMU virt (Cortex-A15), vexpress-a9 (Cortex-A9 with PL310),
> and realview-eb-mpcore (ARM11 MPCore) with PREEMPT_RT, plus non-RT
> virt and vexpress-a9 builds. Cache sysfs output is unchanged for the
> normal platform DTs, and CPU hotplug passes where supported. Additional
> checks cover DT leaf undercounting with KASAN and ARM11 DT cache
> descriptions.
> 
> The full series also passes on a Raspberry Pi 400 with a 32-bit
> PREEMPT_RT 7.2.6-rc1 kernel: the boot warning is absent and all 12 cache
> sysfs entries match the baseline. CPU hotplug is unavailable there.

This makes sense.

Tested-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>

Sebastian