1 files changed, 13 insertions, 0 deletions

diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
index 2b40a6045da..72ec29e1ae0 100644
--- a/arch/x86/kernel/apic/hw_nmi.c
+++ b/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