Re: [PATCH v27 02/10] sched: Avoid donor->sched_class->yield_task() null traversal

[K Prateek Nayak]

Hello John,

On 4/4/2026 11:06 AM, John Stultz wrote:
> With proxy-exec once we do return migration from ttwu(), if a
> task is proxying for a waiting donor, and the donor is woken up,
> we switch the rq->donor to point to idle briefly until we can
> re-enter __schedule().
> 
> However, if a task that was acting as a proxy calls into
> yield() right after the donor is switched to idle, it may
> trip a null  pointer traversal, because the idle task doesn't
> have a yield_task() pointer.

After introduction of proxy_resched_idle(), we shouldn't
have any case of running with rq->idle as donor with a
different rq->curr.

I think we can drop this fix now and squash the changes from
Patch 7 into Patch 6 to even avoid any transient cases during
bisection where this might be possible

Thoughts?

-- 
Thanks and Regards,
Prateek