1 files changed, 29 insertions, 2 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 8855481857b5..e6800fe040ea 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1017,10 +1017,30 @@ static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p)
 		uclamp_rq_dec_id(rq, p, clamp_id);
 }
 
+#ifdef CONFIG_UCLAMP_TASK_GROUP
+static void cpu_util_update_eff(struct cgroup_subsys_state *css);
+static void uclamp_update_root_tg(void)
+{
+	struct task_group *tg = &root_task_group;
+
+	uclamp_se_set(&tg->uclamp_req[UCLAMP_MIN],
+		      sysctl_sched_uclamp_util_min, false);
+	uclamp_se_set(&tg->uclamp_req[UCLAMP_MAX],
+		      sysctl_sched_uclamp_util_max, false);
+
+	rcu_read_lock();
+	cpu_util_update_eff(&root_task_group.css);
+	rcu_read_unlock();
+}
+#else
+static void uclamp_update_root_tg(void) { }
+#endif
+
 int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
 				void __user *buffer, size_t *lenp,
 				loff_t *ppos)
 {
+	bool update_root_tg = false;
 	int old_min, old_max;
 	int result;
 
@@ -1043,16 +1063,23 @@ int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
 	if (old_min != sysctl_sched_uclamp_util_min) {
 		uclamp_se_set(&uclamp_default[UCLAMP_MIN],
 			      sysctl_sched_uclamp_util_min, false);
+		update_root_tg = true;
 	}
 	if (old_max != sysctl_sched_uclamp_util_max) {
 		uclamp_se_set(&uclamp_default[UCLAMP_MAX],
 			      sysctl_sched_uclamp_util_max, false);
+		update_root_tg = true;
 	}
 
+	if (update_root_tg)
+		uclamp_update_root_tg();
+
 	/*
-	 * Updating all the RUNNABLE task is expensive, keep it simple and do
-	 * just a lazy update at each next enqueue time.
+	 * We update all RUNNABLE tasks only when task groups are in use.
+	 * Otherwise, keep it simple and do just a lazy update at each next
+	 * task enqueue time.
 	 */
+
 	goto done;
 
 undo: