[PATCH] check nmi watchdog is broken
A bug against an xSeries system showed up recently noting that the
check_nmi_watchdog() test was failing.
I have been investigating it and discovered in both i386 and x86_64 the
recent change to the routine to use the cpu_callin_map has uncovered a
problem. Prior to that change, on an SMP box, the test was trivally
passing because all cpu's were found to not yet be online, but now with the
callin_map they are discovered, it goes on to test the counter and they
have not yet begun to increment, so it announces a CPU is stuck and bails
out.
On all the systems I have access to test, the announcement of failure is
also bougs... by the time you can login and check /proc/interrupts, the
NMI count is happily incrementing on all CPUs. Its just that the test is
being done too early.
I have tried moving the call to the test around a bit, and it was always
too early. I finally hit on this proposed solution, it delays the routine
via a late_initcall(), seems like the right solution to me.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/x86_64/kernel/nmi.c b/arch/x86_64/kernel/nmi.c
index e00d4ad..61de0b3 100644
--- a/arch/x86_64/kernel/nmi.c
+++ b/arch/x86_64/kernel/nmi.c
@@ -112,17 +112,20 @@
}
}
-int __init check_nmi_watchdog (void)
+static int __init check_nmi_watchdog (void)
{
int counts[NR_CPUS];
int cpu;
+ if (nmi_watchdog == NMI_NONE)
+ return 0;
+
if (nmi_watchdog == NMI_LOCAL_APIC && !cpu_has_lapic()) {
nmi_watchdog = NMI_NONE;
return -1;
}
- printk(KERN_INFO "testing NMI watchdog ... ");
+ printk(KERN_INFO "Testing NMI watchdog ... ");
for (cpu = 0; cpu < NR_CPUS; cpu++)
counts[cpu] = cpu_pda[cpu].__nmi_count;
@@ -148,6 +151,8 @@
return 0;
}
+/* Have this called later during boot so counters are updating */
+late_initcall(check_nmi_watchdog);
int __init setup_nmi_watchdog(char *str)
{