From: Tejun Heo <tj@kernel.org>
Date: Thu, 16 Oct 2025 18:45:38 +0000 (-1000)
Subject: sched_ext: Merge branch 'sched/core' of git://git.kernel.org/pub/scm/linux/kernel... 
X-Git-Tag: v6.19-rc1~177^2~37
X-Git-Url: https://gentwo.org/gitweb/?a=commitdiff_plain;h=70d837c3e017a0dc2bc52abf07abfeebd006c946;p=linux%2F.git

sched_ext: Merge branch 'sched/core' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into for-6.19

Pull in tip/sched/core to receive:

 50653216e4ff ("sched: Add support to pick functions to take rf")
 4c95380701f5 ("sched/ext: Fold balance_scx() into pick_task_scx()")

which will enable clean integration of DL server support among other things.

This conflicts with the following from sched_ext/for-6.18-fixes:

 a8ad873113d3 ("sched_ext: defer queue_balance_callback() until after ops.dispatch")

which adds maybe_queue_balance_callback() to balance_scx() which is removed
by 50653216e4ff. Resolve by moving the invocation to pick_task_scx() in the
equivalent location.

Signed-off-by: Tejun Heo <tj@kernel.org>
---

70d837c3e017a0dc2bc52abf07abfeebd006c946
diff --cc kernel/sched/ext.c
index 5d6fdb31f18a,49f4a9e76348..adff739b396c
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@@ -2387,41 -2298,22 +2351,26 @@@ static struct task_struct *first_local_
  					struct task_struct, scx.dsq_list.node);
  }
  
- static struct task_struct *pick_task_scx(struct rq *rq)
+ static struct task_struct *pick_task_scx(struct rq *rq, struct rq_flags *rf)
  {
  	struct task_struct *prev = rq->curr;
+ 	bool keep_prev, kick_idle = false;
  	struct task_struct *p;
- 	bool keep_prev = rq->scx.flags & SCX_RQ_BAL_KEEP;
- 	bool kick_idle = false;
  
- 	/*
- 	 * WORKAROUND:
- 	 *
- 	 * %SCX_RQ_BAL_KEEP should be set iff $prev is on SCX as it must just
- 	 * have gone through balance_scx(). Unfortunately, there currently is a
- 	 * bug where fair could say yes on balance() but no on pick_task(),
- 	 * which then ends up calling pick_task_scx() without preceding
- 	 * balance_scx().
- 	 *
- 	 * Keep running @prev if possible and avoid stalling from entering idle
- 	 * without balancing.
- 	 *
- 	 * Once fair is fixed, remove the workaround and trigger WARN_ON_ONCE()
- 	 * if pick_task_scx() is called without preceding balance_scx().
- 	 */
- 	if (unlikely(rq->scx.flags & SCX_RQ_BAL_PENDING)) {
- 		if (prev->scx.flags & SCX_TASK_QUEUED) {
- 			keep_prev = true;
- 		} else {
- 			keep_prev = false;
- 			kick_idle = true;
- 		}
- 	} else if (unlikely(keep_prev &&
- 			    prev->sched_class != &ext_sched_class)) {
- 		/*
- 		 * Can happen while enabling as SCX_RQ_BAL_PENDING assertion is
- 		 * conditional on scx_enabled() and may have been skipped.
- 		 */
+ 	rq_modified_clear(rq);
++
+ 	rq_unpin_lock(rq, rf);
+ 	balance_one(rq, prev);
+ 	rq_repin_lock(rq, rf);
++
++	maybe_queue_balance_callback(rq);
++
+ 	if (rq_modified_above(rq, &ext_sched_class))
+ 		return RETRY_TASK;
+ 
+ 	keep_prev = rq->scx.flags & SCX_RQ_BAL_KEEP;
+ 	if (unlikely(keep_prev &&
+ 		     prev->sched_class != &ext_sched_class)) {
  		WARN_ON_ONCE(scx_enable_state() == SCX_ENABLED);
  		keep_prev = false;
  	}