Re: [PATCH -next v1 05/12] srcu: Don't queue workqueue handlers to never-online CPUs

On 5/17/26 20:03, Paul E. McKenney wrote:
> On Sun, May 17, 2026 at 02:47:55PM +0200, Uladzislau Rezki wrote:
>> On Wed, May 13, 2026 at 12:38:01PM +0200, Thorsten Leemhuis wrote:
>>> On 5/11/26 19:54, Uladzislau Rezki (Sony) wrote:
>>>> From: "Paul E. McKenney" <[email protected]>
>>>>
>>>> While an srcu_struct structure is in the midst of switching from CPU-0
>>>> to all-CPUs state, it can attempt to invoke callbacks for CPUs that
>>>> have never been online.  Worse yet, it can attempt in invoke callbacks
>>>> for CPUs that never will be online, even including imaginary CPUs not in
>>>> cpu_possible_mask.  This can cause hangs on s390,
>>>
>>> Uladzislau, Paul, according to the fixes tag below this change fixes a
>>> change that went into 7.0-rc6 -- and apparently causes a "hang" on some
>>> architectures. So shouldn't this be heading to mainline instead of
>>> -next? Ideally with a stable tag to ensure backporting to 7.0.y, but
>>> that is a separate decision?
>>>
>> I assume it will be picked to stable

Thx for the reply. This answered the second aspect I raised. What about
the first: shouldn't this be heading to mainline this cycle, ideally
quite soon? Or is this the plan and I misinterpreted the "-next" in the
subject?

Sadly Jiri (now CCed) afaics didn't yet report if this fix helped to fix
the issues they were seeing, but it sounded a lot like it was likely:
https://lore.kernel.org/all/[email protected]/

>> since there is a "Fixes:" tag. From
>> the other hand i can explicitly update commit message with Cc: [email protected]
>>
>> Paul, any thoughts?
> 
> The "Fixes" tag should cover it.

Often it does, yes, but it might be silently dropped for one reason or
another. So in the end only a stable tag will guarantee backporting
attempt by the stable team.

Site note: I recently also tried to persuade Greg to also take those
with a stable tag first in case there is a huge backlog.

Ciao, Thorsten