The current touch_nmi_watchdog() function in /kernel/watchdog.c does
not always catch all cases when a processor is spinning in the nmi
handler inside either KGDB, KDB, or MDB, in particular, the case where
a processor is being held by a debugger inside an int1 handler.
The hrtimer_interrupts_saved count can still end up matching the
hrtime value in some cases, resulting in the hard lockup detector
tagging processors inside a debugger and executing a panic.
The patch below corrects this problem. I did not add this to
the touch_nmi_function directly becuase of possible affects on
timing issues since the function is widely used by drivers and
modules.
I have tested this patch and it fixes the problem for kernel debuggers
stopping errant hard lockup events when processors are spinning inside
the debugger.
Signed-off-by: Jeff Merkey <linux....@gmail.com>
---
kernel/watchdog.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 18f34cf..b682aab 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -283,6 +283,13 @@ static bool is_hardlockup(void)
__this_cpu_write(hrtimer_interrupts_saved, hrint);
return false;
}
+
+void touch_hardlockup_watchdog(void)
+{
+ __this_cpu_write(hrtimer_interrupts_saved, 0);
+}
+EXPORT_SYMBOL_GPL(touch_hardlockup_watchdog);
+
#endif
static int is_softlockup(unsigned long touch_ts)
--
1.8.3.1
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