---

yaml
---
r: 223972
b: refs/heads/master
c: 554ec06
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 9ab181fa9ff73a38fccd0a4f1c40a38dfe62b535
+refs/heads/master: 554ec063982752e9a569ab9189eeffa3d96731b2

trunk/arch/x86/kernel/apic/hw_nmi.c

@@ -28,10 +28,20 @@ u64 hw_nmi_get_sample_period(void)
 /* For reliability, we're prepared to waste bits here. */
 static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
 
+/* "in progress" flag of arch_trigger_all_cpu_backtrace */
+static unsigned long backtrace_flag;
+
 void arch_trigger_all_cpu_backtrace(void)
 {
 	int i;
 
+	if (test_and_set_bit(0, &backtrace_flag))
+		/*
+		 * If there is already a trigger_all_cpu_backtrace() in progress
+		 * (backtrace_flag == 1), don't output double cpu dump infos.
+		 */
+		return;
+
 	cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
 
 	printk(KERN_INFO "sending NMI to all CPUs:\n");
@@ -43,6 +53,9 @@ void arch_trigger_all_cpu_backtrace(void)
 			break;
 		mdelay(1);
 	}
+
+	clear_bit(0, &backtrace_flag);
+	smp_mb__after_clear_bit();
 }
 
 static int __kprobes