Merge branch 'core-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  debug lockups: Improve lockup detection, fix generic arch fallback
  debug lockups: Improve lockup detection

1 files changed, 13 insertions, 7 deletions

diff --git a/arch/x86/kernel/apic/nmi.c b/arch/x86/kernel/apic/nmi.c
index b3025b43b63a..db7220220d09 100644
--- a/arch/x86/kernel/apic/nmi.c
+++ b/arch/x86/kernel/apic/nmi.c
@@ -39,7 +39,7 @@
 int unknown_nmi_panic;
 int nmi_watchdog_enabled;
 
-static cpumask_var_t backtrace_mask;
+static cpumask_t backtrace_mask __read_mostly;
 
 /* nmi_active:
  * >0: the lapic NMI watchdog is active, but can be disabled
@@ -138,7 +138,6 @@ int __init check_nmi_watchdog(void)
         if (!prev_nmi_count)
                 goto error;
 
-        alloc_cpumask_var(&backtrace_mask, GFP_KERNEL|__GFP_ZERO);
         printk(KERN_INFO "Testing NMI watchdog ... ");
 
 #ifdef CONFIG_SMP
@@ -415,14 +414,17 @@ nmi_watchdog_tick(struct pt_regs *regs, unsigned reason)
         }
 
         /* We can be called before check_nmi_watchdog, hence NULL check. */
-        if (backtrace_mask != NULL && cpumask_test_cpu(cpu, backtrace_mask)) {
+        if (cpumask_test_cpu(cpu, &backtrace_mask)) {
                 static DEFINE_SPINLOCK(lock);   /* Serialise the printks */
 
                 spin_lock(&lock);
                 printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
+                show_regs(regs);
                 dump_stack();
                 spin_unlock(&lock);
-                cpumask_clear_cpu(cpu, backtrace_mask);
+                cpumask_clear_cpu(cpu, &backtrace_mask);
+
+                rc = 1;
         }
 
         /* Could check oops_in_progress here too, but it's safer not to */
@@ -552,14 +554,18 @@ int do_nmi_callback(struct pt_regs *regs, int cpu)
         return 0;
 }
 
-void __trigger_all_cpu_backtrace(void)
+void arch_trigger_all_cpu_backtrace(void)
 {
         int i;
 
-        cpumask_copy(backtrace_mask, cpu_online_mask);
+        cpumask_copy(&backtrace_mask, cpu_online_mask);
+
+        printk(KERN_INFO "sending NMI to all CPUs:\n");
+        apic->send_IPI_all(NMI_VECTOR);
+
         /* Wait for up to 10 seconds for all CPUs to do the backtrace */
         for (i = 0; i < 10 * 1000; i++) {
-                if (cpumask_empty(backtrace_mask))
+                if (cpumask_empty(&backtrace_mask))
                         break;
                 mdelay(1);
         }