[tip: sched/urgent] sched/ext: Fix scx vs sched_delayed

["tip-bot2 for Peter Zijlstra" <tip-bot2@linutronix.de>]

The following commit has been merged into the sched/urgent branch of tip:

Commit-ID:     69d5e722be949a1e2409c3f2865ba6020c279db6
Gitweb:        https://git.kernel.org/tip/69d5e722be949a1e2409c3f2865ba6020c279db6
Author:        Peter Zijlstra <peterz@infradead.org>
AuthorDate:    Wed, 30 Oct 2024 11:49:34 +01:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 30 Oct 2024 22:42:12 +01:00

sched/ext: Fix scx vs sched_delayed

Commit 98442f0ccd82 ("sched: Fix delayed_dequeue vs
switched_from_fair()") forgot about scx :/

Fixes: 98442f0ccd82 ("sched: Fix delayed_dequeue vs switched_from_fair()")
Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lkml.kernel.org/r/20241030104934.GK14555@noisy.programming.kicks-ass.net
---
 kernel/sched/ext.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 40bdfe8..721a754 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -4489,11 +4489,16 @@ static void scx_ops_disable_workfn(struct kthread_work *work)
 	scx_task_iter_start(&sti);
 	while ((p = scx_task_iter_next_locked(&sti))) {
 		const struct sched_class *old_class = p->sched_class;
+		const struct sched_class *new_class =
+			__setscheduler_class(p->policy, p->prio);
 		struct sched_enq_and_set_ctx ctx;
 
+		if (old_class != new_class && p->se.sched_delayed)
+			dequeue_task(task_rq(p), p, DEQUEUE_SLEEP | DEQUEUE_DELAYED);
+
 		sched_deq_and_put_task(p, DEQUEUE_SAVE | DEQUEUE_MOVE, &ctx);
 
-		p->sched_class = __setscheduler_class(p->policy, p->prio);
+		p->sched_class = new_class;
 		check_class_changing(task_rq(p), p, old_class);
 
 		sched_enq_and_set_task(&ctx);
@@ -5199,12 +5204,17 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link)
 	scx_task_iter_start(&sti);
 	while ((p = scx_task_iter_next_locked(&sti))) {
 		const struct sched_class *old_class = p->sched_class;
+		const struct sched_class *new_class =
+			__setscheduler_class(p->policy, p->prio);
 		struct sched_enq_and_set_ctx ctx;
 
+		if (old_class != new_class && p->se.sched_delayed)
+			dequeue_task(task_rq(p), p, DEQUEUE_SLEEP | DEQUEUE_DELAYED);
+
 		sched_deq_and_put_task(p, DEQUEUE_SAVE | DEQUEUE_MOVE, &ctx);
 
 		p->scx.slice = SCX_SLICE_DFL;
-		p->sched_class = __setscheduler_class(p->policy, p->prio);
+		p->sched_class = new_class;
 		check_class_changing(task_rq(p), p, old_class);
 
 		sched_enq_and_set_task(&ctx);