Merge tag 'sched_urgent_for_v5.15_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fixes from Borislav Petkov:

 - Tell the compiler to always inline is_percpu_thread()

 - Make sure tunable_scaling buffer is null-terminated after an update
   in sysfs

 - Fix LTP named regression due to cgroup list ordering

* tag 'sched_urgent_for_v5.15_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Always inline is_percpu_thread()
  sched/fair: Null terminate buffer when updating tunable_scaling
  sched/fair: Add ancestors of unthrottled undecayed cfs_rq

2 files changed, 12 insertions, 2 deletions

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 49716228efb4..17a653b67006 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -173,16 +173,22 @@ static ssize_t sched_scaling_write(struct file *filp, const char __user *ubuf,
 				   size_t cnt, loff_t *ppos)
 {
 	char buf[16];
+	unsigned int scaling;
 
 	if (cnt > 15)
 		cnt = 15;
 
 	if (copy_from_user(&buf, ubuf, cnt))
 		return -EFAULT;
+	buf[cnt] = '\0';
 
-	if (kstrtouint(buf, 10, &sysctl_sched_tunable_scaling))
+	if (kstrtouint(buf, 10, &scaling))
 		return -EINVAL;
 
+	if (scaling >= SCHED_TUNABLESCALING_END)
+		return -EINVAL;
+
+	sysctl_sched_tunable_scaling = scaling;
 	if (sched_update_scaling())
 		return -EINVAL;
 
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ff69f245b939..f6a05d9b5443 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4936,8 +4936,12 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
 	/* update hierarchical throttle state */
 	walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
 
-	if (!cfs_rq->load.weight)
+	/* Nothing to run but something to decay (on_list)? Complete the branch */
+	if (!cfs_rq->load.weight) {
+		if (cfs_rq->on_list)
+			goto unthrottle_throttle;
 		return;
+	}
 
 	task_delta = cfs_rq->h_nr_running;
 	idle_task_delta = cfs_rq->idle_h_nr_running;