From 18957647d10a17b36cd8ecdb31f661aa931ea8a1 Mon Sep 17 00:00:00 2001 From: Florian Bezdeka Date: Wed, 9 Apr 2025 23:33:42 +0200 Subject: [PATCH 4/7] sched/fair: Take care of group/affinity/sched_class change for throttled task On task group change, for tasks whose on_rq equals to TASK_ON_RQ_QUEUED, core will dequeue it and then requeued it. The throttled task is still considered as queued by core because p->on_rq is still set so core will dequeue it, but since the task is already dequeued on throttle in fair, handle this case properly. Affinity and sched class change is similar. [Florian: manual backport to 6.14] Signed-off-by: Aaron Lu Signed-off-by: Florian Bezdeka --- kernel/sched/fair.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8e3c2ae8da64a..fc42ffcfcccb9 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5890,6 +5890,20 @@ void init_cfs_throttle_work(struct task_struct *p) INIT_LIST_HEAD(&p->throttle_node); } +static void dequeue_throttled_task(struct task_struct *p, int flags) +{ + /* + * Task is throttled and someone wants to dequeue it again: + * it must be sched/core when core needs to do things like + * task affinity change, task group change, task sched class + * change etc. + */ + WARN_ON_ONCE(p->se.on_rq); + WARN_ON_ONCE(flags & DEQUEUE_SLEEP); + + list_del_init(&p->throttle_node); +} + static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags); static int tg_unthrottle_up(struct task_group *tg, void *data) { @@ -6723,6 +6737,7 @@ static inline void sync_throttle(struct task_group *tg, int cpu) {} static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} static void task_throttle_setup_work(struct task_struct *p) {} static bool task_is_throttled(struct task_struct *p) { return false; } +static void dequeue_throttled_task(struct task_struct *p, int flags) {} static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) { @@ -7153,6 +7168,11 @@ static int dequeue_entities(struct rq *rq, struct sched_entity *se, int flags) */ static bool dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) { + if (unlikely(task_is_throttled(p))) { + dequeue_throttled_task(p, flags); + return true; + } + if (!(p->se.sched_delayed && (task_on_rq_migrating(p) || (flags & DEQUEUE_SAVE)))) util_est_dequeue(&rq->cfs, p); -- 2.39.5