Merge tag 'sched-urgent-2025-03-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fix from Ingo Molnar:
 "Revert a scheduler performance optimization that regressed other
  workloads"

* tag 'sched-urgent-2025-03-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Revert "sched/core: Reduce cost of sched_move_task when config autogroup"

Author: torvalds

kernel/sched/core.c

@@ -9016,7 +9016,7 @@ void sched_release_group(struct task_group *tg)
 	spin_unlock_irqrestore(&task_group_lock, flags);
 }
 
-static struct task_group *sched_get_task_group(struct task_struct *tsk)
+static void sched_change_group(struct task_struct *tsk)
 {
 	struct task_group *tg;
 
@@ -9028,13 +9028,7 @@ static struct task_group *sched_get_task_group(struct task_struct *tsk)
 	tg = container_of(task_css_check(tsk, cpu_cgrp_id, true),
 			  struct task_group, css);
 	tg = autogroup_task_group(tsk, tg);
-
-	return tg;
-}
-
-static void sched_change_group(struct task_struct *tsk, struct task_group *group)
-{
-	tsk->sched_task_group = group;
+	tsk->sched_task_group = tg;
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
 	if (tsk->sched_class->task_change_group)
@@ -9055,20 +9049,11 @@ void sched_move_task(struct task_struct *tsk, bool for_autogroup)
 {
 	int queued, running, queue_flags =
 		DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
-	struct task_group *group;
 	struct rq *rq;
 
 	CLASS(task_rq_lock, rq_guard)(tsk);
 	rq = rq_guard.rq;
 
-	/*
-	 * Esp. with SCHED_AUTOGROUP enabled it is possible to get superfluous
-	 * group changes.
-	 */
-	group = sched_get_task_group(tsk);
-	if (group == tsk->sched_task_group)
-		return;
-
 	update_rq_clock(rq);
 
 	running = task_current_donor(rq, tsk);
@@ -9079,7 +9064,7 @@ void sched_move_task(struct task_struct *tsk, bool for_autogroup)
 	if (running)
 		put_prev_task(rq, tsk);
 
-	sched_change_group(tsk, group);
+	sched_change_group(tsk);
 	if (!for_autogroup)
 		scx_cgroup_move_task(tsk);