Date:	Thu, 18 Nov 2010 11:11:06 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	mingo@...hat.com, hpa@...or.com, linux-kernel@...r.kernel.org,
	tglx@...utronix.de, dzickus@...hat.com, mingo@...e.hu
CC:	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:perf/core] x86, nmi_watchdog: Remove the old nmi_watchdog

On 11/18/2010 06:05 AM, tip-bot for Don Zickus wrote:
> Commit-ID:  5f2b0ba4d94b3ac23cbc4b7f675d98eb677a760a
> Gitweb:     http://git.kernel.org/tip/5f2b0ba4d94b3ac23cbc4b7f675d98eb677a760a
> Author:     Don Zickus <dzickus@...hat.com>
> AuthorDate: Fri, 12 Nov 2010 11:22:23 -0500
> Committer:  Ingo Molnar <mingo@...e.hu>
> CommitDate: Thu, 18 Nov 2010 09:08:23 +0100
> 
> x86, nmi_watchdog: Remove the old nmi_watchdog
> 
> Now that we have a new nmi_watchdog that is more generic and
> sits on top of the perf subsystem, we really do not need the old
> nmi_watchdog any more.
> 
> In addition, the old nmi_watchdog doesn't really work if you are
> using the default clocksource, hpet.  The old nmi_watchdog code
> relied on local apic interrupts to determine if the cpu is still
> alive.  With hpet as the clocksource, these interrupts don't
> increment any more and the old nmi_watchdog triggers false
> postives.
> 
> This piece removes the old nmi_watchdog code and stubs out any
> variables and functions calls.  The stubs are the same ones used
> by the new nmi_watchdog code, so it should be well tested.
> 
> Signed-off-by: Don Zickus <dzickus@...hat.com>
> Cc: fweisbec@...il.com
> Cc: gorcunov@...nvz.org
> LKML-Reference: <1289578944-28564-2-git-send-email-dzickus@...hat.com>
> Signed-off-by: Ingo Molnar <mingo@...e.hu>
> ---
>  arch/x86/include/asm/nmi.h    |    4 -
>  arch/x86/kernel/apic/Makefile |    5 +-
>  arch/x86/kernel/apic/hw_nmi.c |    6 +-
>  arch/x86/kernel/apic/nmi.c    |  567 -----------------------------------------
>  arch/x86/kernel/traps.c       |    9 -
>  include/linux/nmi.h           |    6 +-
>  kernel/sysctl.c               |   16 --
>  7 files changed, 5 insertions(+), 608 deletions(-)
> 
> diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
> index 932f0f8..33292ec 100644
> --- a/arch/x86/include/asm/nmi.h
> +++ b/arch/x86/include/asm/nmi.h
> @@ -17,9 +17,6 @@ int do_nmi_callback(struct pt_regs *regs, int cpu);
>  
>  extern void die_nmi(char *str, struct pt_regs *regs, int do_panic);
>  extern int check_nmi_watchdog(void);
> -#if !defined(CONFIG_LOCKUP_DETECTOR)
> -extern int nmi_watchdog_enabled;
> -#endif
>  extern int avail_to_resrv_perfctr_nmi_bit(unsigned int);
>  extern int reserve_perfctr_nmi(unsigned int);
>  extern void release_perfctr_nmi(unsigned int);
> @@ -30,7 +27,6 @@ extern void setup_apic_nmi_watchdog(void *);
>  extern void stop_apic_nmi_watchdog(void *);
>  extern void disable_timer_nmi_watchdog(void);
>  extern void enable_timer_nmi_watchdog(void);
> -extern int nmi_watchdog_tick(struct pt_regs *regs, unsigned reason);
>  extern void cpu_nmi_set_wd_enabled(void);
>  
>  extern atomic_t nmi_active;
> diff --git a/arch/x86/kernel/apic/Makefile b/arch/x86/kernel/apic/Makefile
> index 910f20b..3966b56 100644
> --- a/arch/x86/kernel/apic/Makefile
> +++ b/arch/x86/kernel/apic/Makefile
> @@ -3,10 +3,7 @@
>  #
>  
>  obj-$(CONFIG_X86_LOCAL_APIC)	+= apic.o apic_noop.o probe_$(BITS).o ipi.o
> -ifneq ($(CONFIG_HARDLOCKUP_DETECTOR),y)
> -obj-$(CONFIG_X86_LOCAL_APIC)	+= nmi.o
> -endif
> -obj-$(CONFIG_HARDLOCKUP_DETECTOR)	+= hw_nmi.o
> +obj-y				+= hw_nmi.o
>  
>  obj-$(CONFIG_X86_IO_APIC)	+= io_apic.o
>  obj-$(CONFIG_SMP)		+= ipi.o
> diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
> index cefd694..b68b174 100644
> --- a/arch/x86/kernel/apic/hw_nmi.c
> +++ b/arch/x86/kernel/apic/hw_nmi.c
> @@ -20,12 +20,14 @@
>  /* For reliability, we're prepared to waste bits here. */
>  static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
>  
> +#ifdef CONFIG_HARDLOCKUP_DETECTOR
>  u64 hw_nmi_get_sample_period(void)
>  {
>  	return (u64)(cpu_khz) * 1000 * 60;
>  }
> +#endif
>  
> -#ifdef ARCH_HAS_NMI_WATCHDOG
> +#ifdef arch_trigger_all_cpu_backtrace
>  void arch_trigger_all_cpu_backtrace(void)
>  {
>  	int i;
> @@ -95,8 +97,6 @@ early_initcall(register_trigger_all_cpu_backtrace);
>  #if defined(CONFIG_X86_LOCAL_APIC)
>  unsigned int nmi_watchdog = NMI_NONE;
>  EXPORT_SYMBOL(nmi_watchdog);
> -void acpi_nmi_enable(void) { return; }
> -void acpi_nmi_disable(void) { return; }
>  #endif
>  atomic_t nmi_active = ATOMIC_INIT(0);           /* oprofile uses this */
>  EXPORT_SYMBOL(nmi_active);
> diff --git a/arch/x86/kernel/apic/nmi.c b/arch/x86/kernel/apic/nmi.c
> deleted file mode 100644
> index c90041c..0000000
> --- a/arch/x86/kernel/apic/nmi.c
> +++ /dev/null
> @@ -1,567 +0,0 @@
> -/*
> - *  NMI watchdog support on APIC systems
> - *
> - *  Started by Ingo Molnar <mingo@...hat.com>
> - *
> - *  Fixes:
> - *  Mikael Pettersson	: AMD K7 support for local APIC NMI watchdog.
> - *  Mikael Pettersson	: Power Management for local APIC NMI watchdog.
> - *  Mikael Pettersson	: Pentium 4 support for local APIC NMI watchdog.
> - *  Pavel Machek and
> - *  Mikael Pettersson	: PM converted to driver model. Disable/enable API.
> - */
> -
> -#include <asm/apic.h>
> -
> -#include <linux/nmi.h>
> -#include <linux/mm.h>
> -#include <linux/delay.h>
> -#include <linux/interrupt.h>
> -#include <linux/module.h>
> -#include <linux/slab.h>
> -#include <linux/sysdev.h>
> -#include <linux/sysctl.h>
> -#include <linux/percpu.h>
> -#include <linux/kprobes.h>
> -#include <linux/cpumask.h>
> -#include <linux/kernel_stat.h>
> -#include <linux/kdebug.h>
> -#include <linux/smp.h>
> -
> -#include <asm/i8259.h>
> -#include <asm/io_apic.h>
> -#include <asm/proto.h>
> -#include <asm/timer.h>
> -
> -#include <asm/mce.h>
> -
> -#include <asm/mach_traps.h>
> -
> -int unknown_nmi_panic;
> -int nmi_watchdog_enabled;
> -
> -/* For reliability, we're prepared to waste bits here. */
> -static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
> -
> -/* nmi_active:
> - * >0: the lapic NMI watchdog is active, but can be disabled
> - * <0: the lapic NMI watchdog has not been set up, and cannot
> - *     be enabled
> - *  0: the lapic NMI watchdog is disabled, but can be enabled
> - */
> -atomic_t nmi_active = ATOMIC_INIT(0);		/* oprofile uses this */
> -EXPORT_SYMBOL(nmi_active);
> -
> -unsigned int nmi_watchdog = NMI_NONE;
> -EXPORT_SYMBOL(nmi_watchdog);
> -
> -static int panic_on_timeout;
> -
> -static unsigned int nmi_hz = HZ;
> -static DEFINE_PER_CPU(short, wd_enabled);
> -static int endflag __initdata;
> -
> -static inline unsigned int get_nmi_count(int cpu)
> -{
> -	return per_cpu(irq_stat, cpu).__nmi_count;
> -}
> -
> -static inline int mce_in_progress(void)
> -{
> -#if defined(CONFIG_X86_MCE)
> -	return atomic_read(&mce_entry) > 0;
> -#endif
> -	return 0;
> -}
> -
> -/*
> - * Take the local apic timer and PIT/HPET into account. We don't
> - * know which one is active, when we have highres/dyntick on
> - */
> -static inline unsigned int get_timer_irqs(int cpu)
> -{
> -	return per_cpu(irq_stat, cpu).apic_timer_irqs +
> -		per_cpu(irq_stat, cpu).irq0_irqs;
> -}
> -
> -#ifdef CONFIG_SMP
> -/*
> - * The performance counters used by NMI_LOCAL_APIC don't trigger when
> - * the CPU is idle. To make sure the NMI watchdog really ticks on all
> - * CPUs during the test make them busy.
> - */
> -static __init void nmi_cpu_busy(void *data)
> -{
> -	local_irq_enable_in_hardirq();
> -	/*
> -	 * Intentionally don't use cpu_relax here. This is
> -	 * to make sure that the performance counter really ticks,
> -	 * even if there is a simulator or similar that catches the
> -	 * pause instruction. On a real HT machine this is fine because
> -	 * all other CPUs are busy with "useless" delay loops and don't
> -	 * care if they get somewhat less cycles.
> -	 */
> -	while (endflag == 0)
> -		mb();
> -}
> -#endif
> -
> -static void report_broken_nmi(int cpu, unsigned int *prev_nmi_count)
> -{
> -	printk(KERN_CONT "\n");
> -
> -	printk(KERN_WARNING
> -		"WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
> -			cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
> -
> -	printk(KERN_WARNING
> -		"Please report this to bugzilla.kernel.org,\n");
> -	printk(KERN_WARNING
> -		"and attach the output of the 'dmesg' command.\n");
> -
> -	per_cpu(wd_enabled, cpu) = 0;
> -	atomic_dec(&nmi_active);
> -}
> -
> -static void __acpi_nmi_disable(void *__unused)
> -{
> -	apic_write(APIC_LVT0, APIC_DM_NMI | APIC_LVT_MASKED);
> -}
> -
> -int __init check_nmi_watchdog(void)
> -{
> -	unsigned int *prev_nmi_count;
> -	int cpu;
> -
> -	if (!nmi_watchdog_active() || !atomic_read(&nmi_active))
> -		return 0;
> -
> -	prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(int), GFP_KERNEL);
> -	if (!prev_nmi_count)
> -		goto error;
> -
> -	printk(KERN_INFO "Testing NMI watchdog ... ");
> -
> -#ifdef CONFIG_SMP
> -	if (nmi_watchdog == NMI_LOCAL_APIC)
> -		smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
> -#endif
> -
> -	for_each_possible_cpu(cpu)
> -		prev_nmi_count[cpu] = get_nmi_count(cpu);
> -	local_irq_enable();
> -	mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
> -
> -	for_each_online_cpu(cpu) {
> -		if (!per_cpu(wd_enabled, cpu))
> -			continue;
> -		if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
> -			report_broken_nmi(cpu, prev_nmi_count);
> -	}
> -	endflag = 1;
> -	if (!atomic_read(&nmi_active)) {
> -		kfree(prev_nmi_count);
> -		atomic_set(&nmi_active, -1);
> -		goto error;
> -	}
> -	printk("OK.\n");
> -
> -	/*
> -	 * now that we know it works we can reduce NMI frequency to
> -	 * something more reasonable; makes a difference in some configs
> -	 */
> -	if (nmi_watchdog == NMI_LOCAL_APIC)
> -		nmi_hz = lapic_adjust_nmi_hz(1);
> -
> -	kfree(prev_nmi_count);
> -	return 0;
> -error:
> -	if (nmi_watchdog == NMI_IO_APIC) {
> -		if (!timer_through_8259)
> -			legacy_pic->mask(0);
> -		on_each_cpu(__acpi_nmi_disable, NULL, 1);
> -	}
> -
> -#ifdef CONFIG_X86_32
> -	timer_ack = 0;
> -#endif
> -	return -1;
> -}
> -
> -static int __init setup_nmi_watchdog(char *str)
> -{
> -	unsigned int nmi;
> -
> -	if (!strncmp(str, "panic", 5)) {
> -		panic_on_timeout = 1;
> -		str = strchr(str, ',');
> -		if (!str)
> -			return 1;
> -		++str;
> -	}
> -
> -	if (!strncmp(str, "lapic", 5))
> -		nmi_watchdog = NMI_LOCAL_APIC;
> -	else if (!strncmp(str, "ioapic", 6))
> -		nmi_watchdog = NMI_IO_APIC;
> -	else {
> -		get_option(&str, &nmi);
> -		if (nmi >= NMI_INVALID)
> -			return 0;
> -		nmi_watchdog = nmi;
> -	}
> -
> -	return 1;
> -}
> -__setup("nmi_watchdog=", setup_nmi_watchdog);
> -
> -/*
> - * Suspend/resume support
> - */
> -#ifdef CONFIG_PM
> -
> -static int nmi_pm_active; /* nmi_active before suspend */
> -
> -static int lapic_nmi_suspend(struct sys_device *dev, pm_message_t state)
> -{
> -	/* only CPU0 goes here, other CPUs should be offline */
> -	nmi_pm_active = atomic_read(&nmi_active);
> -	stop_apic_nmi_watchdog(NULL);
> -	BUG_ON(atomic_read(&nmi_active) != 0);
> -	return 0;
> -}
> -
> -static int lapic_nmi_resume(struct sys_device *dev)
> -{
> -	/* only CPU0 goes here, other CPUs should be offline */
> -	if (nmi_pm_active > 0) {
> -		setup_apic_nmi_watchdog(NULL);
> -		touch_nmi_watchdog();
> -	}
> -	return 0;
> -}
> -
> -static struct sysdev_class nmi_sysclass = {
> -	.name		= "lapic_nmi",
> -	.resume		= lapic_nmi_resume,
> -	.suspend	= lapic_nmi_suspend,
> -};
> -
> -static struct sys_device device_lapic_nmi = {
> -	.id	= 0,
> -	.cls	= &nmi_sysclass,
> -};
> -
> -static int __init init_lapic_nmi_sysfs(void)
> -{
> -	int error;
> -
> -	/*
> -	 * should really be a BUG_ON but b/c this is an
> -	 * init call, it just doesn't work.  -dcz
> -	 */
> -	if (nmi_watchdog != NMI_LOCAL_APIC)
> -		return 0;
> -
> -	if (atomic_read(&nmi_active) < 0)
> -		return 0;
> -
> -	error = sysdev_class_register(&nmi_sysclass);
> -	if (!error)
> -		error = sysdev_register(&device_lapic_nmi);
> -	return error;
> -}
> -
> -/* must come after the local APIC's device_initcall() */
> -late_initcall(init_lapic_nmi_sysfs);
> -
> -#endif	/* CONFIG_PM */
> -
> -static void __acpi_nmi_enable(void *__unused)
> -{
> -	apic_write(APIC_LVT0, APIC_DM_NMI);
> -}
> -
> -/*
> - * Enable timer based NMIs on all CPUs:
> - */
> -void acpi_nmi_enable(void)
> -{
> -	if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC)
> -		on_each_cpu(__acpi_nmi_enable, NULL, 1);
> -}
> -
> -/*
> - * Disable timer based NMIs on all CPUs:
> - */
> -void acpi_nmi_disable(void)
> -{
> -	if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC)
> -		on_each_cpu(__acpi_nmi_disable, NULL, 1);
> -}
> -
> -/*
> - * This function is called as soon the LAPIC NMI watchdog driver has everything
> - * in place and it's ready to check if the NMIs belong to the NMI watchdog
> - */
> -void cpu_nmi_set_wd_enabled(void)
> -{
> -	__get_cpu_var(wd_enabled) = 1;
> -}
> -
> -void setup_apic_nmi_watchdog(void *unused)
> -{
> -	if (__get_cpu_var(wd_enabled))
> -		return;
> -
> -	/* cheap hack to support suspend/resume */
> -	/* if cpu0 is not active neither should the other cpus */
> -	if (smp_processor_id() != 0 && atomic_read(&nmi_active) <= 0)
> -		return;
> -
> -	switch (nmi_watchdog) {
> -	case NMI_LOCAL_APIC:
> -		if (lapic_watchdog_init(nmi_hz) < 0) {
> -			__get_cpu_var(wd_enabled) = 0;
> -			return;
> -		}
> -		/* FALL THROUGH */
> -	case NMI_IO_APIC:
> -		__get_cpu_var(wd_enabled) = 1;
> -		atomic_inc(&nmi_active);
> -	}
> -}
> -
> -void stop_apic_nmi_watchdog(void *unused)
> -{
> -	/* only support LOCAL and IO APICs for now */
> -	if (!nmi_watchdog_active())
> -		return;
> -	if (__get_cpu_var(wd_enabled) == 0)
> -		return;
> -	if (nmi_watchdog == NMI_LOCAL_APIC)
> -		lapic_watchdog_stop();
> -	else
> -		__acpi_nmi_disable(NULL);
> -	__get_cpu_var(wd_enabled) = 0;
> -	atomic_dec(&nmi_active);
> -}
> -
> -/*
> - * the best way to detect whether a CPU has a 'hard lockup' problem
> - * is to check it's local APIC timer IRQ counts. If they are not
> - * changing then that CPU has some problem.
> - *
> - * as these watchdog NMI IRQs are generated on every CPU, we only
> - * have to check the current processor.
> - *
> - * since NMIs don't listen to _any_ locks, we have to be extremely
> - * careful not to rely on unsafe variables. The printk might lock
> - * up though, so we have to break up any console locks first ...
> - * [when there will be more tty-related locks, break them up here too!]
> - */
> -
> -static DEFINE_PER_CPU(unsigned, last_irq_sum);
> -static DEFINE_PER_CPU(long, alert_counter);
> -static DEFINE_PER_CPU(int, nmi_touch);
> -
> -void touch_nmi_watchdog(void)
> -{
> -	if (nmi_watchdog_active()) {
> -		unsigned cpu;
> -
> -		/*
> -		 * Tell other CPUs to reset their alert counters. We cannot
> -		 * do it ourselves because the alert count increase is not
> -		 * atomic.
> -		 */
> -		for_each_present_cpu(cpu) {
> -			if (per_cpu(nmi_touch, cpu) != 1)
> -				per_cpu(nmi_touch, cpu) = 1;
> -		}
> -	}
> -
> -	/*
> -	 * Tickle the softlockup detector too:
> -	 */
> -	touch_softlockup_watchdog();
> -}
> -EXPORT_SYMBOL(touch_nmi_watchdog);
> -
> -notrace __kprobes int
> -nmi_watchdog_tick(struct pt_regs *regs, unsigned reason)
> -{
> -	/*
> -	 * Since current_thread_info()-> is always on the stack, and we
> -	 * always switch the stack NMI-atomically, it's safe to use
> -	 * smp_processor_id().
> -	 */
> -	unsigned int sum;
> -	int touched = 0;
> -	int cpu = smp_processor_id();
> -	int rc = 0;
> -
> -	sum = get_timer_irqs(cpu);
> -
> -	if (__get_cpu_var(nmi_touch)) {
> -		__get_cpu_var(nmi_touch) = 0;
> -		touched = 1;
> -	}
> -
> -	/* We can be called before check_nmi_watchdog, hence NULL check. */
> -	if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
> -		static DEFINE_RAW_SPINLOCK(lock); /* Serialise the printks */
> -
> -		raw_spin_lock(&lock);
> -		printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
> -		show_regs(regs);
> -		dump_stack();
> -		raw_spin_unlock(&lock);
> -		cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
> -
> -		rc = 1;
> -	}
> -
> -	/* Could check oops_in_progress here too, but it's safer not to */
> -	if (mce_in_progress())
> -		touched = 1;
> -
> -	/* if the none of the timers isn't firing, this cpu isn't doing much */
> -	if (!touched && __get_cpu_var(last_irq_sum) == sum) {
> -		/*
> -		 * Ayiee, looks like this CPU is stuck ...
> -		 * wait a few IRQs (5 seconds) before doing the oops ...
> -		 */
> -		__this_cpu_inc(alert_counter);
> -		if (__this_cpu_read(alert_counter) == 5 * nmi_hz)
> -			/*
> -			 * die_nmi will return ONLY if NOTIFY_STOP happens..
> -			 */
> -			die_nmi("BUG: NMI Watchdog detected LOCKUP",
> -				regs, panic_on_timeout);
> -	} else {
> -		__get_cpu_var(last_irq_sum) = sum;
> -		__this_cpu_write(alert_counter, 0);
> -	}
> -
> -	/* see if the nmi watchdog went off */
> -	if (!__get_cpu_var(wd_enabled))
> -		return rc;
> -	switch (nmi_watchdog) {
> -	case NMI_LOCAL_APIC:
> -		rc |= lapic_wd_event(nmi_hz);
> -		break;
> -	case NMI_IO_APIC:
> -		/*
> -		 * don't know how to accurately check for this.
> -		 * just assume it was a watchdog timer interrupt
> -		 * This matches the old behaviour.
> -		 */
> -		rc = 1;
> -		break;
> -	}
> -	return rc;
> -}
> -
> -#ifdef CONFIG_SYSCTL
> -
> -static void enable_ioapic_nmi_watchdog_single(void *unused)
> -{
> -	__get_cpu_var(wd_enabled) = 1;
> -	atomic_inc(&nmi_active);
> -	__acpi_nmi_enable(NULL);
> -}
> -
> -static void enable_ioapic_nmi_watchdog(void)
> -{
> -	on_each_cpu(enable_ioapic_nmi_watchdog_single, NULL, 1);
> -	touch_nmi_watchdog();
> -}
> -
> -static void disable_ioapic_nmi_watchdog(void)
> -{
> -	on_each_cpu(stop_apic_nmi_watchdog, NULL, 1);
> -}
> -
> -static int __init setup_unknown_nmi_panic(char *str)
> -{
> -	unknown_nmi_panic = 1;
> -	return 1;
> -}
> -__setup("unknown_nmi_panic", setup_unknown_nmi_panic);
> -
> -static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu)
> -{
> -	unsigned char reason = get_nmi_reason();
> -	char buf[64];
> -
> -	sprintf(buf, "NMI received for unknown reason %02x\n", reason);
> -	die_nmi(buf, regs, 1); /* Always panic here */
> -	return 0;
> -}
> -
> -/*
> - * proc handler for /proc/sys/kernel/nmi
> - */
> -int proc_nmi_enabled(struct ctl_table *table, int write,
> -			void __user *buffer, size_t *length, loff_t *ppos)
> -{
> -	int old_state;
> -
> -	nmi_watchdog_enabled = (atomic_read(&nmi_active) > 0) ? 1 : 0;
> -	old_state = nmi_watchdog_enabled;
> -	proc_dointvec(table, write, buffer, length, ppos);
> -	if (!!old_state == !!nmi_watchdog_enabled)
> -		return 0;
> -
> -	if (atomic_read(&nmi_active) < 0 || !nmi_watchdog_active()) {
> -		printk(KERN_WARNING
> -			"NMI watchdog is permanently disabled\n");
> -		return -EIO;
> -	}
> -
> -	if (nmi_watchdog == NMI_LOCAL_APIC) {
> -		if (nmi_watchdog_enabled)
> -			enable_lapic_nmi_watchdog();
> -		else
> -			disable_lapic_nmi_watchdog();
> -	} else if (nmi_watchdog == NMI_IO_APIC) {
> -		if (nmi_watchdog_enabled)
> -			enable_ioapic_nmi_watchdog();
> -		else
> -			disable_ioapic_nmi_watchdog();
> -	} else {
> -		printk(KERN_WARNING
> -			"NMI watchdog doesn't know what hardware to touch\n");
> -		return -EIO;
> -	}
> -	return 0;
> -}
> -
> -#endif /* CONFIG_SYSCTL */
> -
> -int do_nmi_callback(struct pt_regs *regs, int cpu)
> -{
> -#ifdef CONFIG_SYSCTL
> -	if (unknown_nmi_panic)
> -		return unknown_nmi_panic_callback(regs, cpu);
> -#endif
> -	return 0;
> -}
> -
> -void arch_trigger_all_cpu_backtrace(void)
> -{
> -	int i;
> -
> -	cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
> -
> -	printk(KERN_INFO "sending NMI to all CPUs:\n");
> -	apic->send_IPI_all(NMI_VECTOR);
> -
> -	/* Wait for up to 10 seconds for all CPUs to do the backtrace */
> -	for (i = 0; i < 10 * 1000; i++) {
> -		if (cpumask_empty(to_cpumask(backtrace_mask)))
> -			break;
> -		mdelay(1);
> -	}
> -}
> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> index cb838ca..db30d9c 100644
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c
> @@ -398,15 +398,6 @@ static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
>  							== NOTIFY_STOP)
>  			return;
>  
> -#ifndef CONFIG_LOCKUP_DETECTOR
> -		/*
> -		 * Ok, so this is none of the documented NMI sources,
> -		 * so it must be the NMI watchdog.
> -		 */
> -		if (nmi_watchdog_tick(regs, reason))
> -			return;
> -		if (!do_nmi_callback(regs, cpu))
> -#endif /* !CONFIG_LOCKUP_DETECTOR */
>  			unknown_nmi_error(reason, regs);
>  #else
>  		unknown_nmi_error(reason, regs);
> diff --git a/include/linux/nmi.h b/include/linux/nmi.h
> index 06aab5e..0cb3e5c 100644
> --- a/include/linux/nmi.h
> +++ b/include/linux/nmi.h
> @@ -16,10 +16,7 @@
>   */
>  #ifdef ARCH_HAS_NMI_WATCHDOG
>  #include <asm/nmi.h>
> -extern void touch_nmi_watchdog(void);
> -extern void acpi_nmi_disable(void);
> -extern void acpi_nmi_enable(void);
> -#else
> +#endif
>  #ifndef CONFIG_HARDLOCKUP_DETECTOR
>  static inline void touch_nmi_watchdog(void)
>  {
> @@ -30,7 +27,6 @@ extern void touch_nmi_watchdog(void);
>  #endif
>  static inline void acpi_nmi_disable(void) { }
>  static inline void acpi_nmi_enable(void) { }
> -#endif
>  
>  /*
>   * Create trigger_all_cpu_backtrace() out of the arch-provided
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index b65bf63..ce33e2a 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -746,22 +746,6 @@ static struct ctl_table kern_table[] = {
>  		.extra2		= &one,
>  	},
>  #endif
> -#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86) && !defined(CONFIG_LOCKUP_DETECTOR)
> -	{
> -		.procname       = "unknown_nmi_panic",
> -		.data           = &unknown_nmi_panic,
> -		.maxlen         = sizeof (int),
> -		.mode           = 0644,
> -		.proc_handler   = proc_dointvec,
> -	},
> -	{
> -		.procname       = "nmi_watchdog",
> -		.data           = &nmi_watchdog_enabled,
> -		.maxlen         = sizeof (int),
> -		.mode           = 0644,
> -		.proc_handler   = proc_nmi_enabled,
> -	},
> -#endif

Please update the kernel-parameters.txt accordingly.

and you need to keep unknown_nmi_panic or else as early_param().

Also any corresponding part like "nmi_watchdog=off" ?

Thanks

Yinghai Lu

>  #if defined(CONFIG_X86)
>  	{
>  		.procname	= "panic_on_unrecovered_nmi",
> --
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