Re: [PATCH] Revert "sched/core: Tweak wait_task_inactive() to force dequeue sched_delayed tasks"

[K Prateek Nayak]

Hello Matt,

On 9/26/2025 9:04 PM, Matt Fleming wrote:
> On Fri, Sep 26, 2025 at 3:43 AM K Prateek Nayak <kprateek.nayak@xxxxxxx> wrote:
>>
>> Hello John, Matt,
>>
>> On 9/26/2025 5:35 AM, John Stultz wrote:
>>>
>>> However, there are two spots where we might exit dequeue_entities()
>>> early when cfs_rq_throttled(rq), so maybe that's what's catching us
>>> here?
>>
>> That could very likely be it.
> 
> That tracks -- we're heavy users of cgroups and this particular issue
> only appeared on our kubernetes nodes.
> 
>> Matt, if possible can you try the patch attached below to check if the
>> bailout for throttled hierarchy is indeed the root cause. Thanks in
>> advance.
> 
> I've been running our reproducer with this patch for the last few
> hours without any issues, so the fix looks good to me.
> 
> Tested-by: Matt Fleming <mfleming@xxxxxxxxxxxxxx>

Thank you for testing the diff. I see Ingo has already posted the
scheduler pull for v6.18 which indirectly solves this by removing those
early returns.

Once that lands, I'll attach a formal commit log and send out a patch
targeting the stable kernels >= 6.12.

-- 
Thanks and Regards,
Prateek