diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c
index f5bc7e1..a5e34d6 100644
--- a/arch/i386/kernel/nmi.c
+++ b/arch/i386/kernel/nmi.c
@@ -195,6 +195,8 @@
 	return 0;
 }
 
+static int endflag __initdata = 0;
+
 #ifdef CONFIG_SMP
 /* The performance counters used by NMI_LOCAL_APIC don't trigger when
  * the CPU is idle. To make sure the NMI watchdog really ticks on all
@@ -202,7 +204,6 @@
  */
 static __init void nmi_cpu_busy(void *data)
 {
-	volatile int *endflag = data;
 	local_irq_enable_in_hardirq();
 	/* Intentionally don't use cpu_relax here. This is
 	   to make sure that the performance counter really ticks,
@@ -210,14 +211,13 @@
 	   pause instruction. On a real HT machine this is fine because
 	   all other CPUs are busy with "useless" delay loops and don't
 	   care if they get somewhat less cycles. */
-	while (*endflag == 0)
-		barrier();
+	while (endflag == 0)
+		mb();
 }
 #endif
 
 static int __init check_nmi_watchdog(void)
 {
-	volatile int endflag = 0;
 	unsigned int *prev_nmi_count;
 	int cpu;
 
diff --git a/arch/x86_64/kernel/nmi.c b/arch/x86_64/kernel/nmi.c
index 27e95e7..186aebb 100644
--- a/arch/x86_64/kernel/nmi.c
+++ b/arch/x86_64/kernel/nmi.c
@@ -193,6 +193,8 @@
 		nmi_watchdog = NMI_IO_APIC;
 }
 
+static int endflag __initdata = 0;
+
 #ifdef CONFIG_SMP
 /* The performance counters used by NMI_LOCAL_APIC don't trigger when
  * the CPU is idle. To make sure the NMI watchdog really ticks on all
@@ -200,7 +202,6 @@
  */
 static __init void nmi_cpu_busy(void *data)
 {
-	volatile int *endflag = data;
 	local_irq_enable_in_hardirq();
 	/* Intentionally don't use cpu_relax here. This is
 	   to make sure that the performance counter really ticks,
@@ -208,14 +209,13 @@
 	   pause instruction. On a real HT machine this is fine because
 	   all other CPUs are busy with "useless" delay loops and don't
 	   care if they get somewhat less cycles. */
-	while (*endflag == 0)
-		barrier();
+	while (endflag == 0)
+		mb();
 }
 #endif
 
 int __init check_nmi_watchdog (void)
 {
-	volatile int endflag = 0;
 	int *counts;
 	int cpu;
 
@@ -256,6 +256,7 @@
 	if (!atomic_read(&nmi_active)) {
 		kfree(counts);
 		atomic_set(&nmi_active, -1);
+		endflag = 1;
 		return -1;
 	}
 	endflag = 1;