watchdog: Don't throttle the watchdog

Stephane reported that when the machine locks up, the regular ticks, which are responsible to resetting the throttle count, stop too. Hence the NMI watchdog can end up being throttled before it reports on the locked up state, and we end up being sad.. Cure this by having the watchdog overflow reset its own throttle count. Reported-by: Stephane Eranian <eranian@google.com> Tested-by: Stephane Eranian <eranian@google.com> Cc: Don Zickus <dzickus@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1282215916.1926.4696.camel@laptop> Signed-off-by: Ingo Molnar <mingo@elte.hu>

watchdog: Don't throttle the watchdog
Stephane reported that when the machine locks up, the regular ticks, which are responsible to resetting the throttle count, stop too. Hence the NMI watchdog can end up being throttled before it reports on the locked up state, and we end up being sad.. Cure this by having the watchdog overflow reset its own throttle count. Reported-by: Stephane Eranian <eranian@google.com> Tested-by: Stephane Eranian <eranian@google.com> Cc: Don Zickus <dzickus@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1282215916.1926.4696.camel@laptop> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Peter Zijlstra · Ingo Molnar
1 parent ede1b42907
Showing 1 changed file with 3 additions and 0 deletions Side-by-side Diff
kernel/watchdog.c
@@ -206,6 +206,9 @@
 		 struct perf_sample_data *data,
 		 struct pt_regs *regs)
 {
+	/* Ensure the watchdog never gets throttled */
+	event->hw.interrupts = 0;
+
 	if (__get_cpu_var(watchdog_nmi_touch) == true) {
 		__get_cpu_var(watchdog_nmi_touch) = false;
 		return;
...	...	@@ -206,6 +206,9 @@
206	206	struct perf_sample_data *data,
207	207	struct pt_regs *regs)
208	208	{
	209	+ /* Ensure the watchdog never gets throttled */
	210	+ event->hw.interrupts = 0;
	211	+
209	212	if (__get_cpu_var(watchdog_nmi_touch) == true) {
210	213	__get_cpu_var(watchdog_nmi_touch) = false;
211	214	return;