---

yaml
---
r: 376914
b: refs/heads/master
c: 34376a5
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 1b79821fe7855c34030bc2f177660874e0a0ab62
+refs/heads/master: 34376a50fb1fa095b9d0636fa41ed2e73125f214

trunk/kernel/softirq.c

@@ -195,15 +195,20 @@ void local_bh_enable_ip(unsigned long ip)
 EXPORT_SYMBOL(local_bh_enable_ip);
 
 /*
- * We restart softirq processing for at most 2 ms,
- * and if need_resched() is not set.
+ * We restart softirq processing for at most MAX_SOFTIRQ_RESTART times,
+ * but break the loop if need_resched() is set or after 2 ms.
+ * The MAX_SOFTIRQ_TIME provides a nice upper bound in most cases, but in
+ * certain cases, such as stop_machine(), jiffies may cease to
+ * increment and so we need the MAX_SOFTIRQ_RESTART limit as
+ * well to make sure we eventually return from this method.
  *
  * These limits have been established via experimentation.
  * The two things to balance is latency against fairness -
  * we want to handle softirqs as soon as possible, but they
  * should not be able to lock up the box.
  */
 #define MAX_SOFTIRQ_TIME  msecs_to_jiffies(2)
+#define MAX_SOFTIRQ_RESTART 10
 
 asmlinkage void __do_softirq(void)
 {
@@ -212,6 +217,7 @@ asmlinkage void __do_softirq(void)
 	unsigned long end = jiffies + MAX_SOFTIRQ_TIME;
 	int cpu;
 	unsigned long old_flags = current->flags;
+	int max_restart = MAX_SOFTIRQ_RESTART;
 
 	/*
 	 * Mask out PF_MEMALLOC s current task context is borrowed for the
@@ -265,7 +271,8 @@ asmlinkage void __do_softirq(void)
 
 	pending = local_softirq_pending();
 	if (pending) {
-		if (time_before(jiffies, end) && !need_resched())
+		if (time_before(jiffies, end) && !need_resched() &&
+		    --max_restart)
 			goto restart;
 
 		wakeup_softirqd();