diff options
| -rw-r--r-- | include/linux/nmi.h | 5 | ||||
| -rw-r--r-- | kernel/watchdog.c | 123 | ||||
| -rw-r--r-- | lib/Kconfig.debug | 14 |
3 files changed, 135 insertions, 7 deletions
diff --git a/include/linux/nmi.h b/include/linux/nmi.h index db50840e635..c8f8aa0383e 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -14,8 +14,11 @@ * may be used to reset the timeout - for code which intentionally * disables interrupts for a long time. This call is stateless. */ -#if defined(CONFIG_HAVE_NMI_WATCHDOG) || defined(CONFIG_HARDLOCKUP_DETECTOR) +#if defined(CONFIG_HAVE_NMI_WATCHDOG) || defined(CONFIG_HARDLOCKUP_DETECTOR_NMI) #include <asm/nmi.h> +#endif + +#if defined(CONFIG_HAVE_NMI_WATCHDOG) || defined(CONFIG_HARDLOCKUP_DETECTOR) extern void touch_nmi_watchdog(void); #else static inline void touch_nmi_watchdog(void) diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 05039e348f0..e092e5a6cdd 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -45,6 +45,11 @@ static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); static DEFINE_PER_CPU(bool, hard_watchdog_warn); static DEFINE_PER_CPU(bool, watchdog_nmi_touch); static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); +#endif +#ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU +static cpumask_t __read_mostly watchdog_cpus; +#endif +#ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); #endif @@ -178,7 +183,7 @@ void touch_softlockup_watchdog_sync(void) __raw_get_cpu_var(watchdog_touch_ts) = 0; } -#ifdef CONFIG_HARDLOCKUP_DETECTOR +#ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI /* watchdog detector functions */ static int is_hardlockup(void) { @@ -192,6 +197,76 @@ static int is_hardlockup(void) } #endif +#ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU +static unsigned int watchdog_next_cpu(unsigned int cpu) +{ + cpumask_t cpus = watchdog_cpus; + unsigned int next_cpu; + + next_cpu = cpumask_next(cpu, &cpus); + if (next_cpu >= nr_cpu_ids) + next_cpu = cpumask_first(&cpus); + + if (next_cpu == cpu) + return nr_cpu_ids; + + return next_cpu; +} + +static int is_hardlockup_other_cpu(unsigned int cpu) +{ + unsigned long hrint = per_cpu(hrtimer_interrupts, cpu); + + if (per_cpu(hrtimer_interrupts_saved, cpu) == hrint) + return 1; + + per_cpu(hrtimer_interrupts_saved, cpu) = hrint; + return 0; +} + +static void watchdog_check_hardlockup_other_cpu(void) +{ + unsigned int next_cpu; + + /* + * Test for hardlockups every 3 samples. The sample period is + * watchdog_thresh * 2 / 5, so 3 samples gets us back to slightly over + * watchdog_thresh (over by 20%). + */ + if (__this_cpu_read(hrtimer_interrupts) % 3 != 0) + return; + + /* check for a hardlockup on the next cpu */ + next_cpu = watchdog_next_cpu(smp_processor_id()); + if (next_cpu >= nr_cpu_ids) + return; + + smp_rmb(); + + if (per_cpu(watchdog_nmi_touch, next_cpu) == true) { + per_cpu(watchdog_nmi_touch, next_cpu) = false; + return; + } + + if (is_hardlockup_other_cpu(next_cpu)) { + /* only warn once */ + if (per_cpu(hard_watchdog_warn, next_cpu) == true) + return; + + if (hardlockup_panic) + panic("Watchdog detected hard LOCKUP on cpu %u", next_cpu); + else + WARN(1, "Watchdog detected hard LOCKUP on cpu %u", next_cpu); + + per_cpu(hard_watchdog_warn, next_cpu) = true; + } else { + per_cpu(hard_watchdog_warn, next_cpu) = false; + } +} +#else +static inline void watchdog_check_hardlockup_other_cpu(void) { return; } +#endif + static int is_softlockup(unsigned long touch_ts) { unsigned long now = get_timestamp(); @@ -203,7 +278,7 @@ static int is_softlockup(unsigned long touch_ts) return 0; } -#ifdef CONFIG_HARDLOCKUP_DETECTOR +#ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI static struct perf_event_attr wd_hw_attr = { .type = PERF_TYPE_HARDWARE, @@ -251,7 +326,7 @@ static void watchdog_overflow_callback(struct perf_event *event, __this_cpu_write(hard_watchdog_warn, false); return; } -#endif /* CONFIG_HARDLOCKUP_DETECTOR */ +#endif /* CONFIG_HARDLOCKUP_DETECTOR_NMI */ static void watchdog_interrupt_count(void) { @@ -271,6 +346,9 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) /* kick the hardlockup detector */ watchdog_interrupt_count(); + /* test for hardlockups on the next cpu */ + watchdog_check_hardlockup_other_cpu(); + /* kick the softlockup detector */ wake_up_process(__this_cpu_read(softlockup_watchdog)); @@ -395,7 +473,7 @@ static void watchdog(unsigned int cpu) __touch_watchdog(); } -#ifdef CONFIG_HARDLOCKUP_DETECTOR +#ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI /* * People like the simple clean cpu node info on boot. * Reduce the watchdog noise by only printing messages @@ -471,9 +549,44 @@ static void watchdog_nmi_disable(unsigned int cpu) return; } #else +#ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU +static int watchdog_nmi_enable(unsigned int cpu) +{ + /* + * The new cpu will be marked online before the first hrtimer interrupt + * runs on it. If another cpu tests for a hardlockup on the new cpu + * before it has run its first hrtimer, it will get a false positive. + * Touch the watchdog on the new cpu to delay the first check for at + * least 3 sampling periods to guarantee one hrtimer has run on the new + * cpu. + */ + per_cpu(watchdog_nmi_touch, cpu) = true; + smp_wmb(); + cpumask_set_cpu(cpu, &watchdog_cpus); + return 0; +} + +static void watchdog_nmi_disable(unsigned int cpu) +{ + unsigned int next_cpu = watchdog_next_cpu(cpu); + + /* + * Offlining this cpu will cause the cpu before this one to start + * checking the one after this one. If this cpu just finished checking + * the next cpu and updating hrtimer_interrupts_saved, and then the + * previous cpu checks it within one sample period, it will trigger a + * false positive. Touch the watchdog on the next cpu to prevent it. + */ + if (next_cpu < nr_cpu_ids) + per_cpu(watchdog_nmi_touch, next_cpu) = true; + smp_wmb(); + cpumask_clear_cpu(cpu, &watchdog_cpus); +} +#else static int watchdog_nmi_enable(unsigned int cpu) { return 0; } static void watchdog_nmi_disable(unsigned int cpu) { return; } -#endif /* CONFIG_HARDLOCKUP_DETECTOR */ +#endif /* CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU */ +#endif /* CONFIG_HARDLOCKUP_DETECTOR_NMI */ /* prepare/enable/disable routines */ /* sysctl functions */ diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 8e642918a1c..86ed2395e58 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -191,15 +191,27 @@ config LOCKUP_DETECTOR The overhead should be minimal. A periodic hrtimer runs to generate interrupts and kick the watchdog task every 4 seconds. An NMI is generated every 10 seconds or so to check for hardlockups. + If NMIs are not available on the platform, every 12 seconds the + hrtimer interrupt on one cpu will be used to check for hardlockups + on the next cpu. The frequency of hrtimer and NMI events and the soft and hard lockup thresholds can be controlled through the sysctl watchdog_thresh. -config HARDLOCKUP_DETECTOR +config HARDLOCKUP_DETECTOR_NMI def_bool y depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI +config HARDLOCKUP_DETECTOR_OTHER_CPU + def_bool y + depends on LOCKUP_DETECTOR && SMP + depends on !HARDLOCKUP_DETECTOR_NMI && !HAVE_NMI_WATCHDOG + +config HARDLOCKUP_DETECTOR + def_bool y + depends on HARDLOCKUP_DETECTOR_NMI || HARDLOCKUP_DETECTOR_OTHER_CPU + config BOOTPARAM_HARDLOCKUP_PANIC bool "Panic (Reboot) On Hard Lockups" depends on HARDLOCKUP_DETECTOR |