diff --git a/[refs] b/[refs]
index c82a7754c0d7..4883408f7779 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e9d95bf7eb929b9ddc9af9f4327b76c77ed4c7d6
+refs/heads/master: 8083e4ad970e4eb567e31037060cdd4ba346f0c0
diff --git a/trunk/include/linux/tick.h b/trunk/include/linux/tick.h
index 8cf8cfe2cc97..98921a3e1aa8 100644
--- a/trunk/include/linux/tick.h
+++ b/trunk/include/linux/tick.h
@@ -126,7 +126,7 @@ static inline ktime_t tick_nohz_get_sleep_length(void)
 	return len;
 }
 static inline void tick_nohz_stop_idle(int cpu) { }
-static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return 0; }
+static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; }
 # endif /* !NO_HZ */
 
 #endif
diff --git a/trunk/kernel/time/tick-sched.c b/trunk/kernel/time/tick-sched.c
index cb02324bdb88..a4d219398167 100644
--- a/trunk/kernel/time/tick-sched.c
+++ b/trunk/kernel/time/tick-sched.c
@@ -20,6 +20,7 @@
 #include <linux/profile.h>
 #include <linux/sched.h>
 #include <linux/tick.h>
+#include <linux/module.h>
 
 #include <asm/irq_regs.h>
 
@@ -190,9 +191,17 @@ u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time)
 {
 	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
 
-	*last_update_time = ktime_to_us(ts->idle_lastupdate);
+	if (!tick_nohz_enabled)
+		return -1;
+
+	if (ts->idle_active)
+		*last_update_time = ktime_to_us(ts->idle_lastupdate);
+	else
+		*last_update_time = ktime_to_us(ktime_get());
+
 	return ktime_to_us(ts->idle_sleeptime);
 }
+EXPORT_SYMBOL_GPL(get_cpu_idle_time_us);
 
 /**
  * tick_nohz_stop_sched_tick - stop the idle tick from the idle task