Merge tag 'sched-urgent-2025-02-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
"Fix a cfs_rq->h_nr_runnable accounting bug that trips up a defensive
SCHED_WARN_ON() on certain workloads. The bug is believed to be
(accidentally) self-correcting, hence no behavioral side effects are
expected.
Also print se.slice in debug output, since this value can now be set
via the syscall ABI and can be useful to track"
* tag 'sched-urgent-2025-02-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/debug: Provide slice length for fair tasks
sched/fair: Fix inaccurate h_nr_runnable accounting with delayed dequeue
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index fd7e852..ef047ad 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -1262,6 +1262,8 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
if (task_has_dl_policy(p)) {
P(dl.runtime);
P(dl.deadline);
+ } else if (fair_policy(p->policy)) {
+ P(se.slice);
}
#ifdef CONFIG_SCHED_CLASS_EXT
__PS("ext.enabled", task_on_scx(p));
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ce2e94c..1c0ef43 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5385,6 +5385,15 @@ static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
static void set_delayed(struct sched_entity *se)
{
se->sched_delayed = 1;
+
+ /*
+ * Delayed se of cfs_rq have no tasks queued on them.
+ * Do not adjust h_nr_runnable since dequeue_entities()
+ * will account it for blocked tasks.
+ */
+ if (!entity_is_task(se))
+ return;
+
for_each_sched_entity(se) {
struct cfs_rq *cfs_rq = cfs_rq_of(se);
@@ -5397,6 +5406,16 @@ static void set_delayed(struct sched_entity *se)
static void clear_delayed(struct sched_entity *se)
{
se->sched_delayed = 0;
+
+ /*
+ * Delayed se of cfs_rq have no tasks queued on them.
+ * Do not adjust h_nr_runnable since a dequeue has
+ * already accounted for it or an enqueue of a task
+ * below it will account for it in enqueue_task_fair().
+ */
+ if (!entity_is_task(se))
+ return;
+
for_each_sched_entity(se) {
struct cfs_rq *cfs_rq = cfs_rq_of(se);
