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    SubjectRe: [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@redhat.com>
    > AuthorDate: Fri, 12 Nov 2010 11:22:23 -0500
    > Committer: Ingo Molnar <mingo@elte.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@redhat.com>
    > Cc: fweisbec@gmail.com
    > Cc: gorcunov@openvz.org
    > LKML-Reference: <1289578944-28564-2-git-send-email-dzickus@redhat.com>
    > Signed-off-by: Ingo Molnar <mingo@elte.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@redhat.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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