diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index f91d85cd121b..3f3f09a021db 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6739,6 +6739,7 @@ static int tg_unthrottle_up(struct task_group *tg, void *data) struct rq *rq = data; struct cfs_rq *cfs_rq = tg_cfs_rq(tg, cpu_of(rq)); struct task_struct *p, *tmp; + LIST_HEAD(throttled_tasks); /* * If cfs_rq->curr is set, the cfs_rq might not have caught up @@ -6769,13 +6770,31 @@ static int tg_unthrottle_up(struct task_group *tg, void *data) cfs_rq->throttled_clock_self_time += delta; } + /* + * Move the tasks to a local list since an update_curr() during + * enqueue_task_fair() can throttle a higher cfs_rq, and it can + * see the "throttled_limbo_list" being non-empty in + * tg_throttle_down() if throttle_count turned 0 above. + */ + list_splice_init(&cfs_rq->throttled_limbo_list, &throttled_tasks); + /* Re-enqueue the tasks that have been throttled at this level. */ - list_for_each_entry_safe(p, tmp, &cfs_rq->throttled_limbo_list, throttle_node) { + list_for_each_entry_safe(p, tmp, &throttled_tasks, throttle_node) { + /* + * Back to being throttled! Break out and put the remaining + * tasks back onto the limbo_list to prevent running them + * unnecessarily. + */ + if (cfs_rq->throttle_count) + break; + list_del_init(&p->throttle_node); p->throttled = false; - enqueue_task_fair(rq_of(cfs_rq), p, ENQUEUE_WAKEUP); + enqueue_task_fair(rq, p, ENQUEUE_WAKEUP); } + list_splice(&throttled_tasks, &cfs_rq->throttled_limbo_list); + /* Add cfs_rq with load or one or more already running entities to the list */ if (!cfs_rq_is_decayed(cfs_rq)) list_add_leaf_cfs_rq(cfs_rq);