Merge tag 'sched_urgent_for_v5.13_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fix from Borislav Petkov:
 "A single fix to restore fairness between control groups with equal
  priority"

* tag 'sched_urgent_for_v5.13_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Correctly insert cfs_rq's to list on unthrottle

1 files changed, 25 insertions, 19 deletions

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 2c8a9352590d..bfaa6e1f6067 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3298,6 +3298,24 @@ static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq, int flags)
 
 #ifdef CONFIG_SMP
 #ifdef CONFIG_FAIR_GROUP_SCHED
+
+static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
+{
+	if (cfs_rq->load.weight)
+		return false;
+
+	if (cfs_rq->avg.load_sum)
+		return false;
+
+	if (cfs_rq->avg.util_sum)
+		return false;
+
+	if (cfs_rq->avg.runnable_sum)
+		return false;
+
+	return true;
+}
+
 /**
  * update_tg_load_avg - update the tg's load avg
  * @cfs_rq: the cfs_rq whose avg changed
@@ -4091,6 +4109,11 @@ static inline void update_misfit_status(struct task_struct *p, struct rq *rq)
 
 #else /* CONFIG_SMP */
 
+static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
+{
+	return true;
+}
+
 #define UPDATE_TG	0x0
 #define SKIP_AGE_LOAD	0x0
 #define DO_ATTACH	0x0
@@ -4749,8 +4772,8 @@ static int tg_unthrottle_up(struct task_group *tg, void *data)
 		cfs_rq->throttled_clock_task_time += rq_clock_task(rq) -
 					     cfs_rq->throttled_clock_task;
 
-		/* Add cfs_rq with already running entity in the list */
-		if (cfs_rq->nr_running >= 1)
+		/* Add cfs_rq with load or one or more already running entities to the list */
+		if (!cfs_rq_is_decayed(cfs_rq) || cfs_rq->nr_running)
 			list_add_leaf_cfs_rq(cfs_rq);
 	}
 
@@ -7996,23 +8019,6 @@ static bool __update_blocked_others(struct rq *rq, bool *done)
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
 
-static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
-{
-	if (cfs_rq->load.weight)
-		return false;
-
-	if (cfs_rq->avg.load_sum)
-		return false;
-
-	if (cfs_rq->avg.util_sum)
-		return false;
-
-	if (cfs_rq->avg.runnable_sum)
-		return false;
-
-	return true;
-}
-
 static bool __update_blocked_fair(struct rq *rq, bool *done)
 {
 	struct cfs_rq *cfs_rq, *pos;