[mirror_ubuntu-eoan-kernel.git] / kernel / softlockup.c

/*
 * Detect Soft Lockups
 *
 * started by Ingo Molnar, Copyright (C) 2005, 2006 Red Hat, Inc.
 *
 * this code detects soft lockups: incidents in where on a CPU
 * the kernel does not reschedule for 10 seconds or more.
 */
#include <linux/mm.h>
#include <linux/cpu.h>
#include <linux/nmi.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/notifier.h>
#include <linux/module.h>

#include <asm/irq_regs.h>

static DEFINE_SPINLOCK(print_lock);

static DEFINE_PER_CPU(unsigned long, touch_timestamp);
static DEFINE_PER_CPU(unsigned long, print_timestamp);
static DEFINE_PER_CPU(struct task_struct *, watchdog_task);

static int __read_mostly did_panic;
int __read_mostly softlockup_thresh = 60;

/*
 * Should we panic (and reboot, if panic_timeout= is set) when a
 * soft-lockup occurs:
 */
unsigned int __read_mostly softlockup_panic =
				CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;

static int __init softlockup_panic_setup(char *str)
{
	softlockup_panic = simple_strtoul(str, NULL, 0);

	return 1;
}
__setup("softlockup_panic=", softlockup_panic_setup);

static int
softlock_panic(struct notifier_block *this, unsigned long event, void *ptr)
{
	did_panic = 1;

	return NOTIFY_DONE;
}

static struct notifier_block panic_block = {
	.notifier_call = softlock_panic,
};

/*
 * Returns seconds, approximately.  We don't need nanosecond
 * resolution, and we don't need to waste time with a big divide when
 * 2^30ns == 1.074s.
 */
static unsigned long get_timestamp(int this_cpu)
{
	return cpu_clock(this_cpu) >> 30LL;  /* 2^30 ~= 10^9 */
}

static void __touch_softlockup_watchdog(void)
{
	int this_cpu = raw_smp_processor_id();

	__raw_get_cpu_var(touch_timestamp) = get_timestamp(this_cpu);
}

void touch_softlockup_watchdog(void)
{
	__raw_get_cpu_var(touch_timestamp) = 0;
}
EXPORT_SYMBOL(touch_softlockup_watchdog);

void touch_all_softlockup_watchdogs(void)
{
	int cpu;

	/* Cause each CPU to re-update its timestamp rather than complain */
	for_each_online_cpu(cpu)
		per_cpu(touch_timestamp, cpu) = 0;
}
EXPORT_SYMBOL(touch_all_softlockup_watchdogs);

/*
 * This callback runs from the timer interrupt, and checks
 * whether the watchdog thread has hung or not:
 */
void softlockup_tick(void)
{
	int this_cpu = smp_processor_id();
	unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu);
	unsigned long print_timestamp;
	struct pt_regs *regs = get_irq_regs();
	unsigned long now;

	/* Is detection switched off? */
	if (!per_cpu(watchdog_task, this_cpu) || softlockup_thresh <= 0) {
		/* Be sure we don't false trigger if switched back on */
		if (touch_timestamp)
			per_cpu(touch_timestamp, this_cpu) = 0;
		return;
	}

	if (touch_timestamp == 0) {
		__touch_softlockup_watchdog();
		return;
	}

	print_timestamp = per_cpu(print_timestamp, this_cpu);

	/* report at most once a second */
	if ((print_timestamp >= touch_timestamp &&
			print_timestamp < (touch_timestamp + 1)) ||
			did_panic) {
		return;
	}

	/* do not print during early bootup: */
	if (unlikely(system_state != SYSTEM_RUNNING)) {
		__touch_softlockup_watchdog();
		return;
	}

	now = get_timestamp(this_cpu);

	/* Wake up the high-prio watchdog task every second: */
	if (now > (touch_timestamp + 1))
		wake_up_process(per_cpu(watchdog_task, this_cpu));

	/* Warn about unreasonable delays: */
	if (now <= (touch_timestamp + softlockup_thresh))
		return;

	per_cpu(print_timestamp, this_cpu) = touch_timestamp;

	spin_lock(&print_lock);
	printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n",
			this_cpu, now - touch_timestamp,
			current->comm, task_pid_nr(current));
	if (regs)
		show_regs(regs);
	else
		dump_stack();
	spin_unlock(&print_lock);

	if (softlockup_panic)
		panic("softlockup: hung tasks");
}

/*
 * Have a reasonable limit on the number of tasks checked:
 */
unsigned long __read_mostly sysctl_hung_task_check_count = 1024;

/*
 * Zero means infinite timeout - no checking done:
 */
unsigned long __read_mostly sysctl_hung_task_timeout_secs = 120;

unsigned long __read_mostly sysctl_hung_task_warnings = 10;

/*
 * Only do the hung-tasks check on one CPU:
 */
static int check_cpu __read_mostly = -1;

static void check_hung_task(struct task_struct *t, unsigned long now)
{
	unsigned long switch_count = t->nvcsw + t->nivcsw;

	if (t->flags & PF_FROZEN)
		return;

	if (switch_count != t->last_switch_count || !t->last_switch_timestamp) {
		t->last_switch_count = switch_count;
		t->last_switch_timestamp = now;
		return;
	}
	if ((long)(now - t->last_switch_timestamp) <
					sysctl_hung_task_timeout_secs)
		return;
	if (sysctl_hung_task_warnings < 0)
		return;
	sysctl_hung_task_warnings--;

	/*
	 * Ok, the task did not get scheduled for more than 2 minutes,
	 * complain:
	 */
	printk(KERN_ERR "INFO: task %s:%d blocked for more than "
			"%ld seconds.\n", t->comm, t->pid,
			sysctl_hung_task_timeout_secs);
	printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
			" disables this message.\n");
	sched_show_task(t);
	__debug_show_held_locks(t);

	t->last_switch_timestamp = now;
	touch_nmi_watchdog();

	if (softlockup_panic)
		panic("softlockup: blocked tasks");
}

/*
 * Check whether a TASK_UNINTERRUPTIBLE does not get woken up for
 * a really long time (120 seconds). If that happens, print out
 * a warning.
 */
static void check_hung_uninterruptible_tasks(int this_cpu)
{
	int max_count = sysctl_hung_task_check_count;
	unsigned long now = get_timestamp(this_cpu);
	struct task_struct *g, *t;

	/*
	 * If the system crashed already then all bets are off,
	 * do not report extra hung tasks:
	 */
	if ((tainted & TAINT_DIE) || did_panic)
		return;

	read_lock(&tasklist_lock);
	do_each_thread(g, t) {
		if (!--max_count)
			goto unlock;
		if (t->state & TASK_UNINTERRUPTIBLE)
			check_hung_task(t, now);
	} while_each_thread(g, t);
 unlock:
	read_unlock(&tasklist_lock);
}

/*
 * The watchdog thread - runs every second and touches the timestamp.
 */
static int watchdog(void *__bind_cpu)
{
	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
	int this_cpu = (long)__bind_cpu;

	sched_setscheduler(current, SCHED_FIFO, &param);

	/* initialize timestamp */
	__touch_softlockup_watchdog();

	set_current_state(TASK_INTERRUPTIBLE);
	/*
	 * Run briefly once per second to reset the softlockup timestamp.
	 * If this gets delayed for more than 60 seconds then the
	 * debug-printout triggers in softlockup_tick().
	 */
	while (!kthread_should_stop()) {
		__touch_softlockup_watchdog();
		schedule();

		if (kthread_should_stop())
			break;

		if (this_cpu == check_cpu) {
			if (sysctl_hung_task_timeout_secs)
				check_hung_uninterruptible_tasks(this_cpu);
		}

		set_current_state(TASK_INTERRUPTIBLE);
	}
	__set_current_state(TASK_RUNNING);

	return 0;
}

/*
 * Create/destroy watchdog threads as CPUs come and go:
 */
static int __cpuinit
cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
{
	int hotcpu = (unsigned long)hcpu;
	struct task_struct *p;

	switch (action) {
	case CPU_UP_PREPARE:
	case CPU_UP_PREPARE_FROZEN:
		BUG_ON(per_cpu(watchdog_task, hotcpu));
		p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu);
		if (IS_ERR(p)) {
			printk(KERN_ERR "watchdog for %i failed\n", hotcpu);
			return NOTIFY_BAD;
		}
		per_cpu(touch_timestamp, hotcpu) = 0;
		per_cpu(watchdog_task, hotcpu) = p;
		kthread_bind(p, hotcpu);
		break;
	case CPU_ONLINE:
	case CPU_ONLINE_FROZEN:
		check_cpu = any_online_cpu(cpu_online_map);
		wake_up_process(per_cpu(watchdog_task, hotcpu));
		break;
#ifdef CONFIG_HOTPLUG_CPU
	case CPU_DOWN_PREPARE:
	case CPU_DOWN_PREPARE_FROZEN:
		if (hotcpu == check_cpu) {
			cpumask_t temp_cpu_online_map = cpu_online_map;

			cpu_clear(hotcpu, temp_cpu_online_map);
			check_cpu = any_online_cpu(temp_cpu_online_map);
		}
		break;

	case CPU_UP_CANCELED:
	case CPU_UP_CANCELED_FROZEN:
		if (!per_cpu(watchdog_task, hotcpu))
			break;
		/* Unbind so it can run.  Fall thru. */
		kthread_bind(per_cpu(watchdog_task, hotcpu),
			     any_online_cpu(cpu_online_map));
	case CPU_DEAD:
	case CPU_DEAD_FROZEN:
		p = per_cpu(watchdog_task, hotcpu);
		per_cpu(watchdog_task, hotcpu) = NULL;
		kthread_stop(p);
		break;
#endif /* CONFIG_HOTPLUG_CPU */
	}
	return NOTIFY_OK;
}

static struct notifier_block __cpuinitdata cpu_nfb = {
	.notifier_call = cpu_callback
};

__init void spawn_softlockup_task(void)
{
	void *cpu = (void *)(long)smp_processor_id();
	int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);

	BUG_ON(err == NOTIFY_BAD);
	cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
	register_cpu_notifier(&cpu_nfb);

	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
}
Commit	Line	Data
8446f1d3 IM	1	/*
	2	* Detect Soft Lockups
	3	*
6687a97d	4	* started by Ingo Molnar, Copyright (C) 2005, 2006 Red Hat, Inc.
8446f1d3 IM	5	*
	6	* this code detects soft lockups: incidents in where on a CPU
	7	* the kernel does not reschedule for 10 seconds or more.
	8	*/
8446f1d3 IM	9	#include <linux/mm.h>
8446f1d3 IM	10	#include <linux/cpu.h>
82a1fcb9	11	#include <linux/nmi.h>
8446f1d3 IM	12	#include <linux/init.h>
8446f1d3 IM	13	#include <linux/delay.h>
83144186	14	#include <linux/freezer.h>
8446f1d3 IM	15	#include <linux/kthread.h>
	16	#include <linux/notifier.h>
	17	#include <linux/module.h>
	18
43581a10 IM	19	#include <asm/irq_regs.h>
43581a10 IM	20
8446f1d3 IM	21	static DEFINE_SPINLOCK(print_lock);
8446f1d3 IM	22
6687a97d IM	23	static DEFINE_PER_CPU(unsigned long, touch_timestamp);
6687a97d IM	24	static DEFINE_PER_CPU(unsigned long, print_timestamp);
8446f1d3 IM	25	static DEFINE_PER_CPU(struct task_struct *, watchdog_task);
8446f1d3 IM	26
90739081	27	static int __read_mostly did_panic;
9383d967	28	int __read_mostly softlockup_thresh = 60;
6687a97d	29
9c44bc03 IM	30	/*
	31	* Should we panic (and reboot, if panic_timeout= is set) when a
	32	* soft-lockup occurs:
	33	*/
	34	unsigned int __read_mostly softlockup_panic =
	35	CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
	36
	37	static int __init softlockup_panic_setup(char *str)
	38	{
	39	softlockup_panic = simple_strtoul(str, NULL, 0);
	40
	41	return 1;
	42	}
	43	__setup("softlockup_panic=", softlockup_panic_setup);
	44
6687a97d IM	45	static int
6687a97d IM	46	softlock_panic(struct notifier_block this, unsigned long event, void ptr)
8446f1d3 IM	47	{
	48	did_panic = 1;
	49
	50	return NOTIFY_DONE;
	51	}
	52
	53	static struct notifier_block panic_block = {
	54	.notifier_call = softlock_panic,
	55	};
	56
966812dc JF	57	/*
	58	* Returns seconds, approximately. We don't need nanosecond
	59	* resolution, and we don't need to waste time with a big divide when
	60	* 2^30ns == 1.074s.
	61	*/
a3b13c23	62	static unsigned long get_timestamp(int this_cpu)
966812dc	63	{
82a1fcb9	64	return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */
966812dc JF	65	}
966812dc JF	66
8c2238ea	67	static void __touch_softlockup_watchdog(void)
8446f1d3	68	{
a3b13c23 IM	69	int this_cpu = raw_smp_processor_id();
	70
	71	__raw_get_cpu_var(touch_timestamp) = get_timestamp(this_cpu);
8446f1d3	72	}
8c2238ea JW	73
	74	void touch_softlockup_watchdog(void)
	75	{
	76	__raw_get_cpu_var(touch_timestamp) = 0;
	77	}
8446f1d3 IM	78	EXPORT_SYMBOL(touch_softlockup_watchdog);
8446f1d3 IM	79
04c9167f JF	80	void touch_all_softlockup_watchdogs(void)
	81	{
	82	int cpu;
	83
	84	/* Cause each CPU to re-update its timestamp rather than complain */
	85	for_each_online_cpu(cpu)
	86	per_cpu(touch_timestamp, cpu) = 0;
	87	}
	88	EXPORT_SYMBOL(touch_all_softlockup_watchdogs);
	89
8446f1d3 IM	90	/*
	91	* This callback runs from the timer interrupt, and checks
	92	* whether the watchdog thread has hung or not:
	93	*/
6687a97d	94	void softlockup_tick(void)
8446f1d3 IM	95	{
8446f1d3 IM	96	int this_cpu = smp_processor_id();
6687a97d	97	unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu);
966812dc	98	unsigned long print_timestamp;
43581a10	99	struct pt_regs *regs = get_irq_regs();
966812dc	100	unsigned long now;
8446f1d3	101
9383d967 DS	102	/* Is detection switched off? */
	103	if (!per_cpu(watchdog_task, this_cpu) \|\| softlockup_thresh <= 0) {
	104	/* Be sure we don't false trigger if switched back on */
	105	if (touch_timestamp)
	106	per_cpu(touch_timestamp, this_cpu) = 0;
	107	return;
	108	}
	109
04c9167f	110	if (touch_timestamp == 0) {
8c2238ea	111	__touch_softlockup_watchdog();
966812dc	112	return;
04c9167f	113	}
966812dc JF	114
	115	print_timestamp = per_cpu(print_timestamp, this_cpu);
	116
	117	/* report at most once a second */
a115d5ca IM	118	if ((print_timestamp >= touch_timestamp &&
a115d5ca IM	119	print_timestamp < (touch_timestamp + 1)) \|\|
9383d967	120	did_panic) {
8446f1d3	121	return;
a115d5ca	122	}
8446f1d3	123
6687a97d IM	124	/* do not print during early bootup: */
6687a97d IM	125	if (unlikely(system_state != SYSTEM_RUNNING)) {
8c2238ea	126	__touch_softlockup_watchdog();
8446f1d3	127	return;
6687a97d	128	}
8446f1d3	129
a3b13c23	130	now = get_timestamp(this_cpu);
966812dc	131
ed50d6cb PZ	132	/* Wake up the high-prio watchdog task every second: */
	133	if (now > (touch_timestamp + 1))
	134	wake_up_process(per_cpu(watchdog_task, this_cpu));
	135
82a1fcb9	136	/* Warn about unreasonable delays: */
c4f3b63f	137	if (now <= (touch_timestamp + softlockup_thresh))
43581a10	138	return;
8446f1d3	139
43581a10 IM	140	per_cpu(print_timestamp, this_cpu) = touch_timestamp;
	141
	142	spin_lock(&print_lock);
c4f3b63f RT	143	printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n",
c4f3b63f RT	144	this_cpu, now - touch_timestamp,
ba25f9dc	145	current->comm, task_pid_nr(current));
43581a10 IM	146	if (regs)
	147	show_regs(regs);
	148	else
6687a97d	149	dump_stack();
43581a10	150	spin_unlock(&print_lock);
9c44bc03 IM	151
	152	if (softlockup_panic)
	153	panic("softlockup: hung tasks");
8446f1d3 IM	154	}
8446f1d3 IM	155
82a1fcb9 IM	156	/*
	157	* Have a reasonable limit on the number of tasks checked:
	158	*/
90739081	159	unsigned long __read_mostly sysctl_hung_task_check_count = 1024;
82a1fcb9 IM	160
	161	/*
	162	* Zero means infinite timeout - no checking done:
	163	*/
90739081	164	unsigned long __read_mostly sysctl_hung_task_timeout_secs = 120;
82a1fcb9	165
90739081	166	unsigned long __read_mostly sysctl_hung_task_warnings = 10;
82a1fcb9 IM	167
	168	/*
	169	* Only do the hung-tasks check on one CPU:
	170	*/
	171	static int check_cpu __read_mostly = -1;
	172
	173	static void check_hung_task(struct task_struct *t, unsigned long now)
	174	{
	175	unsigned long switch_count = t->nvcsw + t->nivcsw;
	176
	177	if (t->flags & PF_FROZEN)
	178	return;
	179
	180	if (switch_count != t->last_switch_count \|\| !t->last_switch_timestamp) {
	181	t->last_switch_count = switch_count;
	182	t->last_switch_timestamp = now;
	183	return;
	184	}
	185	if ((long)(now - t->last_switch_timestamp) <
	186	sysctl_hung_task_timeout_secs)
	187	return;
	188	if (sysctl_hung_task_warnings < 0)
	189	return;
	190	sysctl_hung_task_warnings--;
	191
	192	/*
	193	* Ok, the task did not get scheduled for more than 2 minutes,
	194	* complain:
	195	*/
	196	printk(KERN_ERR "INFO: task %s:%d blocked for more than "
	197	"%ld seconds.\n", t->comm, t->pid,
	198	sysctl_hung_task_timeout_secs);
	199	printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
	200	" disables this message.\n");
	201	sched_show_task(t);
	202	__debug_show_held_locks(t);
	203
	204	t->last_switch_timestamp = now;
	205	touch_nmi_watchdog();
9c44bc03 IM	206
	207	if (softlockup_panic)
	208	panic("softlockup: blocked tasks");
82a1fcb9 IM	209	}
	210
	211	/*
	212	* Check whether a TASK_UNINTERRUPTIBLE does not get woken up for
	213	* a really long time (120 seconds). If that happens, print out
	214	* a warning.
	215	*/
	216	static void check_hung_uninterruptible_tasks(int this_cpu)
	217	{
	218	int max_count = sysctl_hung_task_check_count;
	219	unsigned long now = get_timestamp(this_cpu);
	220	struct task_struct g, t;
	221
	222	/*
	223	* If the system crashed already then all bets are off,
	224	* do not report extra hung tasks:
	225	*/
	226	if ((tainted & TAINT_DIE) \|\| did_panic)
	227	return;
	228
	229	read_lock(&tasklist_lock);
	230	do_each_thread(g, t) {
	231	if (!--max_count)
ed50d6cb	232	goto unlock;
82a1fcb9 IM	233	if (t->state & TASK_UNINTERRUPTIBLE)
	234	check_hung_task(t, now);
	235	} while_each_thread(g, t);
ed50d6cb	236	unlock:
82a1fcb9 IM	237	read_unlock(&tasklist_lock);
	238	}
	239
8446f1d3 IM	240	/*
	241	* The watchdog thread - runs every second and touches the timestamp.
	242	*/
a5f2ce3c	243	static int watchdog(void *__bind_cpu)
8446f1d3	244	{
02fb6149	245	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
82a1fcb9	246	int this_cpu = (long)__bind_cpu;
8446f1d3 IM	247
8446f1d3 IM	248	sched_setscheduler(current, SCHED_FIFO, &param);
8446f1d3	249
966812dc	250	/* initialize timestamp */
8c2238ea	251	__touch_softlockup_watchdog();
966812dc	252
7be2a03e	253	set_current_state(TASK_INTERRUPTIBLE);
8446f1d3	254	/*
6687a97d	255	* Run briefly once per second to reset the softlockup timestamp.
82a1fcb9	256	* If this gets delayed for more than 60 seconds then the
6687a97d	257	* debug-printout triggers in softlockup_tick().
8446f1d3 IM	258	*/
8446f1d3 IM	259	while (!kthread_should_stop()) {
8c2238ea	260	__touch_softlockup_watchdog();
ed50d6cb PZ	261	schedule();
	262
	263	if (kthread_should_stop())
	264	break;
82a1fcb9	265
7be2a03e DA	266	if (this_cpu == check_cpu) {
	267	if (sysctl_hung_task_timeout_secs)
	268	check_hung_uninterruptible_tasks(this_cpu);
	269	}
ed50d6cb	270
7be2a03e	271	set_current_state(TASK_INTERRUPTIBLE);
8446f1d3	272	}
7be2a03e	273	__set_current_state(TASK_RUNNING);
8446f1d3 IM	274
	275	return 0;
	276	}
	277
	278	/*
	279	* Create/destroy watchdog threads as CPUs come and go:
	280	*/
8c78f307	281	static int __cpuinit
8446f1d3 IM	282	cpu_callback(struct notifier_block nfb, unsigned long action, void hcpu)
	283	{
	284	int hotcpu = (unsigned long)hcpu;
	285	struct task_struct *p;
	286
	287	switch (action) {
	288	case CPU_UP_PREPARE:
8bb78442	289	case CPU_UP_PREPARE_FROZEN:
8446f1d3 IM	290	BUG_ON(per_cpu(watchdog_task, hotcpu));
	291	p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu);
	292	if (IS_ERR(p)) {
a5f2ce3c	293	printk(KERN_ERR "watchdog for %i failed\n", hotcpu);
8446f1d3 IM	294	return NOTIFY_BAD;
8446f1d3 IM	295	}
a5f2ce3c IM	296	per_cpu(touch_timestamp, hotcpu) = 0;
a5f2ce3c IM	297	per_cpu(watchdog_task, hotcpu) = p;
8446f1d3	298	kthread_bind(p, hotcpu);
a5f2ce3c	299	break;
8446f1d3	300	case CPU_ONLINE:
8bb78442	301	case CPU_ONLINE_FROZEN:
82a1fcb9	302	check_cpu = any_online_cpu(cpu_online_map);
8446f1d3 IM	303	wake_up_process(per_cpu(watchdog_task, hotcpu));
	304	break;
	305	#ifdef CONFIG_HOTPLUG_CPU
82a1fcb9 IM	306	case CPU_DOWN_PREPARE:
	307	case CPU_DOWN_PREPARE_FROZEN:
	308	if (hotcpu == check_cpu) {
	309	cpumask_t temp_cpu_online_map = cpu_online_map;
	310
	311	cpu_clear(hotcpu, temp_cpu_online_map);
	312	check_cpu = any_online_cpu(temp_cpu_online_map);
	313	}
	314	break;
ed50d6cb PZ	315
	316	case CPU_UP_CANCELED:
	317	case CPU_UP_CANCELED_FROZEN:
	318	if (!per_cpu(watchdog_task, hotcpu))
	319	break;
	320	/* Unbind so it can run. Fall thru. */
	321	kthread_bind(per_cpu(watchdog_task, hotcpu),
	322	any_online_cpu(cpu_online_map));
8446f1d3	323	case CPU_DEAD:
8bb78442	324	case CPU_DEAD_FROZEN:
8446f1d3 IM	325	p = per_cpu(watchdog_task, hotcpu);
	326	per_cpu(watchdog_task, hotcpu) = NULL;
	327	kthread_stop(p);
	328	break;
	329	#endif /* CONFIG_HOTPLUG_CPU */
a5f2ce3c	330	}
8446f1d3 IM	331	return NOTIFY_OK;
	332	}
	333
8c78f307	334	static struct notifier_block __cpuinitdata cpu_nfb = {
8446f1d3 IM	335	.notifier_call = cpu_callback
	336	};
	337
	338	__init void spawn_softlockup_task(void)
	339	{
	340	void cpu = (void )(long)smp_processor_id();
07dccf33	341	int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
8446f1d3	342
07dccf33	343	BUG_ON(err == NOTIFY_BAD);
8446f1d3 IM	344	cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
	345	register_cpu_notifier(&cpu_nfb);
	346
e041c683	347	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
8446f1d3	348	}