Merge: sched: several fixes from sched/urgent for 9.8

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/7612

JIRA: https://issues.redhat.com/browse/RHEL-128251

Several fixes have landed upstream circa v6.18 for
things we have in EL9. Pull them in to 9.8 to prevent
later issues.

Signed-off-by: Phil Auld <pauld@redhat.com>

Approved-by: Herton R. Krzesinski <herton@redhat.com>
Approved-by: Waiman Long <longman@redhat.com>
Approved-by: Juri Lelli <juri.lelli@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: CKI GitLab Kmaint Pipeline Bot <26919896-cki-kmaint-pipeline-bot@users.noreply.gitlab.com>

Author: CKI KWF Bot

kernel/sched/fair.c

@@ -8489,21 +8489,21 @@ done: __maybe_unused;
 	return p;
 
 idle:
-	if (!rf)
-		return NULL;
-
-	new_tasks = sched_balance_newidle(rq, rf);
+	if (rf) {
+		new_tasks = sched_balance_newidle(rq, rf);
 
-	/*
-	 * Because sched_balance_newidle() releases (and re-acquires) rq->lock, it is
-	 * possible for any higher priority task to appear. In that case we
-	 * must re-start the pick_next_entity() loop.
-	 */
-	if (new_tasks < 0)
-		return RETRY_TASK;
+		/*
+		 * Because sched_balance_newidle() releases (and re-acquires)
+		 * rq->lock, it is possible for any higher priority task to
+		 * appear. In that case we must re-start the pick_next_entity()
+		 * loop.
+		 */
+		if (new_tasks < 0)
+			return RETRY_TASK;
 
-	if (new_tasks > 0)
-		goto again;
+		if (new_tasks > 0)
+			goto again;
+	}
 
 	/*
 	 * rq is about to be idle, check if we need to update the

kernel/sched/topology.c

@@ -2252,6 +2252,8 @@ int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node)
 		goto unlock;
 
 	hop_masks = bsearch(&k, k.masks, sched_domains_numa_levels, sizeof(k.masks[0]), hop_cmp);
+	if (!hop_masks)
+		goto unlock;
 	hop = hop_masks	- k.masks;
 
 	ret = hop ?