---

yaml
---
r: 189431
b: refs/heads/master
c: 8bb39f9
h: refs/heads/master
i:
  189429: b85731d
  189427: a501001
  189423: 18a714c
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 257ef9d21f1b008a6c7425544b36641c4325a922
+refs/heads/master: 8bb39f9aa068262732fe44b965d7a6eb5a5a7d67

trunk/kernel/perf_event.c

@@ -3376,15 +3376,23 @@ static void perf_event_task_output(struct perf_event *event,
 				     struct perf_task_event *task_event)
 {
 	struct perf_output_handle handle;
-	int size;
 	struct task_struct *task = task_event->task;
-	int ret;
+	unsigned long flags;
+	int size, ret;
+
+	/*
+	 * If this CPU attempts to acquire an rq lock held by a CPU spinning
+	 * in perf_output_lock() from interrupt context, it's game over.
+	 */
+	local_irq_save(flags);
 
 	size  = task_event->event_id.header.size;
 	ret = perf_output_begin(&handle, event, size, 0, 0);
 
-	if (ret)
+	if (ret) {
+		local_irq_restore(flags);
 		return;
+	}
 
 	task_event->event_id.pid = perf_event_pid(event, task);
 	task_event->event_id.ppid = perf_event_pid(event, current);
@@ -3395,6 +3403,7 @@ static void perf_event_task_output(struct perf_event *event,
 	perf_output_put(&handle, task_event->event_id);
 
 	perf_output_end(&handle);
+	local_irq_restore(flags);
 }
 
 static int perf_event_task_match(struct perf_event *event)