Re: [PATCH -v2 15/17] sched: Fix migrate_disable() vs rt/dl balancing

[Dietmar Eggemann]

On 05/10/2020 16:57, Peter Zijlstra wrote:

[...]

> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -1859,7 +1859,7 @@ static struct task_struct *pick_next_pus
>   * running task can migrate over to a CPU that is running a task
>   * of lesser priority.
>   */
> -static int push_rt_task(struct rq *rq)
> +static int push_rt_task(struct rq *rq, bool pull)
>  {
>  	struct task_struct *next_task;
>  	struct rq *lowest_rq;
> @@ -1873,6 +1873,34 @@ static int push_rt_task(struct rq *rq)
>  		return 0;
>  
>  retry:
> +	if (is_migration_disabled(next_task)) {
> +		struct task_struct *push_task = NULL;
> +		int cpu;
> +
> +		if (!pull || rq->push_busy)
> +			return 0;

Shouldn't there be the same functionality in push_dl_task(), i.e.
returning 0 earlier for a task with migration_disabled?

[...]