Commit ac1f5912 authored by Don Zickus's avatar Don Zickus Committed by Linus Torvalds

kernel/watchdog.c: add sysctl knob hardlockup_panic

The only way to enable a hardlockup to panic the machine is to set
'nmi_watchdog=panic' on the kernel command line.

This makes it awkward for end users and folks who want to run automate
tests (like myself).

Mimic the softlockup_panic knob and create a /proc/sys/kernel/hardlockup_panic
Signed-off-by: default avatarDon Zickus <>
Cc: Ulrich Obergfell <>
Acked-by: default avatarJiri Kosina <>
Reviewed-by: default avatarAaron Tomlin <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 55537871
......@@ -20,8 +20,9 @@ kernel mode for more than 10 seconds (see "Implementation" below for
details), without letting other interrupts have a chance to run.
Similarly to the softlockup case, the current stack trace is displayed
upon detection and the system will stay locked up unless the default
behavior is changed, which can be done through a compile time knob,
"BOOTPARAM_HARDLOCKUP_PANIC", and a kernel parameter, "nmi_watchdog"
behavior is changed, which can be done through a sysctl,
'hardlockup_panic', a compile time knob, "BOOTPARAM_HARDLOCKUP_PANIC",
and a kernel parameter, "nmi_watchdog"
(see "Documentation/kernel-parameters.txt" for details).
The panic option can be used in combination with panic_timeout (this
......@@ -384,6 +384,7 @@ extern int proc_dowatchdog_thresh(struct ctl_table *table, int write,
void __user *buffer,
size_t *lenp, loff_t *ppos);
extern unsigned int softlockup_panic;
extern unsigned int hardlockup_panic;
void lockup_detector_init(void);
static inline void touch_softlockup_watchdog(void)
......@@ -888,6 +888,17 @@ static struct ctl_table kern_table[] = {
.extra1 = &zero,
.extra2 = &one,
.procname = "hardlockup_panic",
.data = &hardlockup_panic,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &zero,
.extra2 = &one,
.procname = "softlockup_all_cpu_backtrace",
......@@ -112,7 +112,7 @@ static unsigned long soft_lockup_nmi_warn;
* Should we panic when a soft-lockup or hard-lockup occurs:
static int hardlockup_panic =
unsigned int __read_mostly hardlockup_panic =
static unsigned long hardlockup_allcpu_dumped;
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