Re: [PATCH sched_ext/for-6.12-fixes] sched_ext: Call __balance_callbacks() from __scx_task_iter_rq_unlock()

[Peter Zijlstra]

On Wed, Oct 30, 2024 at 11:41:39AM -1000, Tejun Heo wrote:

> --- a/kernel/sched/ext.c
> +++ b/kernel/sched/ext.c
> @@ -1315,6 +1315,8 @@ static void scx_task_iter_start(struct s
>  static void __scx_task_iter_rq_unlock(struct scx_task_iter *iter)
>  {
>  	if (iter->locked) {
> +		/* ->switched_from() may have scheduled balance callbacks */
> +		__balance_callbacks(iter->rq);
>  		task_rq_unlock(iter->rq, iter->locked, &iter->rf);
>  		iter->locked = NULL;
>  	}

I think you need to unpin/repin around it. The balance callbacks like to
drop rq->lock at times.