Re: [PATCH v5 05/29] sched/deadline: Do not divide by zero active CPUs of a root domain

[Juri Lelli]

On 09/11/26 09:57, Mathieu Desnoyers wrote:
> On 2026-11-09 09:30, Juri Lelli wrote:
> [...]
> > This 2nd hunk complements and tightens 4043f54984161 ("sched/deadline:
> > Reject debugfs dl_server writes for offline CPUs") which has Fixes:
> > d741f297bcea ("sched/fair: Fair server interface"). Do we need both
> > fixes (if that is allowed) or maybe we need to split this change in two
> > (as this second part won't apply to old kernels w/o dl-servers)?
> 
> Good point. I will split it in two in the next version:
> 
> - __dl_sub() and __dl_add() skip the division when the root domain has
>   no active CPU. Fixes: daec57983670. This alone removes the divide
>   error, on the debugfs path too.
> - The debugfs write is refused while the runqueue is offline. Fixes:
>   4043f5498416, which it completes for the hotplug windows. It only
>   applies where that commit is.

Hummm, I'm not sure we can say it fixes 4043f5498416, which was a
correct, but only incomplete, fix for d741f297bcea (which the second
hunk fixes properly).