[PATCH] fix "NMI appears to be stuck"

  Testing NMI watchdog ... CPU#0: NMI appears to be stuck (54->54)!
  CPU#1: NMI appears to be stuck (0->0)!

Keep the PIT/HPET alive when nmi_watchdog = 1 is given on the command
line.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 2 deletions

diff --git a/arch/i386/kernel/apic.c b/arch/i386/kernel/apic.c
index 7a2c9cbdb511..2383bcf18c5d 100644
--- a/arch/i386/kernel/apic.c
+++ b/arch/i386/kernel/apic.c
@@ -493,8 +493,15 @@ void __init setup_boot_APIC_clock(void)
                 /* No broadcast on UP ! */
                 if (num_possible_cpus() == 1)
                         return;
-        } else
-                lapic_clockevent.features &= ~CLOCK_EVT_FEAT_DUMMY;
+        } else {
+                /*
+                 * If nmi_watchdog is set to IO_APIC, we need the
+                 * PIT/HPET going.  Otherwise register lapic as a dummy
+                 * device.
+                 */
+                if (nmi_watchdog != NMI_IO_APIC)
+                        lapic_clockevent.features &= ~CLOCK_EVT_FEAT_DUMMY;
+        }
 
         /* Setup the lapic or request the broadcast */
         setup_APIC_timer();