coherency issue observed after hotplug on POWER8

[Krzysztof Kozlowski]

On 24/09/2021 19:17, Naveen N. Rao wrote:
> Hi Cascardo,
> Thanks for reporting this.
> 
> 
> Thadeu Lima de Souza Cascardo wrote:
>> Hi, there.
>>
>> We have been investigating an issue we have observed on POWER8 POWERNV systems.
>> When running the kernel selftests reuseport_bpf_cpu after a CPU hotplug, we see
>> crashes, in different forms. [1]
> 
> Just to re-confirm: you are only seeing this on P8 powernv, and not in a 
> P8 guest/LPAR? I haven't been able to reproduce this on a firestone -- 
> can you share more details about your power8 machine?
> 
> Also, do you only see this with ubuntu kernels, or are you also able to 
> reproduce this with the upstream tree?

Let me just covert this part of your email:

Upstream trees (5.11, 5.13, 5.14). See also:
https://bugs.launchpad.net/ubuntu-power-systems/+bug/1927076/comments/28

I could not reproduce it on Power8 LPAR. Neither on Power9 QEMU guest.

Reproduced on few machines:
IBM, POWER8NVL, 8335-GTB
POWER8, 8001-22C and 8335-GTA

lspcpu for the last one:
https://bugs.launchpad.net/ubuntu-power-systems/+bug/1927076/comments/15


Best regards,
Krzysztof