Re: [PATCH 3/3 v6] s390/pai: Support CPU hotplug for PMU PAI

[sashiko-bot@kernel.org]

> The command 'perf stat -e pai_crypto/CRYPTO_ALL/ -- <command>'
> crashes the kernel when CPUs are hotplug added during that run.
> 
> Root cause is the missing allocation of per-CPU data structures
> for that new CPU. The allocation is dynamic and the first
> event that has task context creates such a structure for
> each online CPU. This is not sufficient. CPUs may be offline
> during event creation and can be set online during the
> perf run time. For example commands
> 
>  # echo 0 > /sys/devices/system/cpu/cpu1/online
>  # perf stat -e cycles -i -- stress-ng -t10s --matrix X
>  # sleep 1
>  # echo 1 > /sys/devices/system/cpu/cpu1/online
> 
> [ ... ]
> 
>  #Cc: stable@vger.kernel.org # v6.19
> Fixes: 582cc1b28e8c ("s390/pai_ext: Enable per-task and system-wide sampling event")
> Fixes: 9f66572f2889 ("s390/pai_crypto: Enable per-task and system-wide sampling event")
> Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260825072931.3738180-1-tmricht@linux.ibm.com?part=3