Re: [mainline][BUG] Observed Workqueue lockups on offline CPUs.

[Samir M <samir@linux.ibm.com>]

On 30/04/26 8:30 pm, Paul E. McKenney wrote:
> On Thu, Apr 30, 2026 at 11:49:02AM +0530, Samir M wrote:
>> On 29/04/26 11:21 pm, Shrikanth Hegde wrote:
>>> Hi Samir.
>>>
>>> On 4/29/26 3:46 PM, Samir M wrote:
>>>> Hi Boqun,
>>>>
>>>> Thank you for pointing me to the existing patches. I have tested
>>>> both Paul's patch [1] and TJ's workqueue patch [2] on my PowerPC
>>>> system (80 CPUs), and can confirm that the workqueue lockup issue is
>>>> not observed.
>>>>
>>> Can you try only paul's patch and confirm if the issue is fixed?
>>>
>> Hi Shrikanth,
>>
>> I have verified Paul’s “alone” patch, and it resolves the issue no workqueue
>> lockups are observed.
> Thank you, Samir!  May I add your Tested-by?
>
> 							Thanx, Paul

Hi Paul,

Yes, you may add:
Tested-by: Samir <samir@linux.ibm.com>

Thanks,
Samir
>> Regards,
>> Samir.
>>
>>
>>>> Test Environment:
>>>> - System: PowerPC with 80 CPUs ( e.g. PowerPC LPARs with 80 online
>>>> and 384 possible CPUs)
>>>> - Kernel version: Latest upstream (7.1-rc1)
>>>>
>>>> Regression Testing Results:
>>>> All tests completed successfully with no issues observed:
>>>> - Hackbench
>>>> - Kernel selftests
>>>> - LTP scheduler tests
>>>>
>>>> The workqueue lockup that was previously occurring is no longer
>>>> present with the patches applied.
>>>>
>>>> References:
>>>> [1]: https://lore.kernel.org/rcu/ed1fa6cd-7343-4ca3-8b9d-
>>>> d699ca496f83@paulmck-laptop/
>>>> [2]: https://lore.kernel.org/rcu/adlHKowvhn8AGXCc@slm.duckdns.org/
>>>>
>>>> Best regards,
>>>> Samir