diff options
Diffstat (limited to 'kernel/watchdog.c')
-rw-r--r-- | kernel/watchdog.c | 101 |
1 files changed, 82 insertions, 19 deletions
diff --git a/kernel/watchdog.c b/kernel/watchdog.c index c3319bd1b040..70bf11815f84 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -15,11 +15,6 @@ #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/lockdep.h> -#include <linux/notifier.h> #include <linux/module.h> #include <linux/sysctl.h> #include <linux/smpboot.h> @@ -47,6 +42,7 @@ static DEFINE_PER_CPU(bool, softlockup_touch_sync); static DEFINE_PER_CPU(bool, soft_watchdog_warn); static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); +static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved); #ifdef CONFIG_HARDLOCKUP_DETECTOR static DEFINE_PER_CPU(bool, hard_watchdog_warn); static DEFINE_PER_CPU(bool, watchdog_nmi_touch); @@ -63,6 +59,25 @@ static unsigned long soft_lockup_nmi_warn; static int hardlockup_panic = CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; +static bool hardlockup_detector_enabled = true; +/* + * We may not want to enable hard lockup detection by default in all cases, + * for example when running the kernel as a guest on a hypervisor. In these + * cases this function can be called to disable hard lockup detection. This + * function should only be executed once by the boot processor before the + * kernel command line parameters are parsed, because otherwise it is not + * possible to override this in hardlockup_panic_setup(). + */ +void watchdog_enable_hardlockup_detector(bool val) +{ + hardlockup_detector_enabled = val; +} + +bool watchdog_hardlockup_detector_is_enabled(void) +{ + return hardlockup_detector_enabled; +} + static int __init hardlockup_panic_setup(char *str) { if (!strncmp(str, "panic", 5)) @@ -71,6 +86,14 @@ static int __init hardlockup_panic_setup(char *str) hardlockup_panic = 0; else if (!strncmp(str, "0", 1)) watchdog_user_enabled = 0; + else if (!strncmp(str, "1", 1) || !strncmp(str, "2", 1)) { + /* + * Setting 'nmi_watchdog=1' or 'nmi_watchdog=2' (legacy option) + * has the same effect. + */ + watchdog_user_enabled = 1; + watchdog_enable_hardlockup_detector(true); + } return 1; } __setup("nmi_watchdog=", hardlockup_panic_setup); @@ -185,7 +208,7 @@ void touch_nmi_watchdog(void) * case we shouldn't have to worry about the watchdog * going off. */ - __raw_get_cpu_var(watchdog_nmi_touch) = true; + raw_cpu_write(watchdog_nmi_touch, true); touch_softlockup_watchdog(); } EXPORT_SYMBOL(touch_nmi_watchdog); @@ -194,8 +217,8 @@ EXPORT_SYMBOL(touch_nmi_watchdog); void touch_softlockup_watchdog_sync(void) { - __raw_get_cpu_var(softlockup_touch_sync) = true; - __raw_get_cpu_var(watchdog_touch_ts) = 0; + __this_cpu_write(softlockup_touch_sync, true); + __this_cpu_write(watchdog_touch_ts, 0); } #ifdef CONFIG_HARDLOCKUP_DETECTOR @@ -260,9 +283,11 @@ static void watchdog_overflow_callback(struct perf_event *event, return; if (hardlockup_panic) - panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu); + panic("Watchdog detected hard LOCKUP on cpu %d", + this_cpu); else - WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu); + WARN(1, "Watchdog detected hard LOCKUP on cpu %d", + this_cpu); __this_cpu_write(hard_watchdog_warn, true); return; @@ -331,8 +356,22 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) return HRTIMER_RESTART; /* only warn once */ - if (__this_cpu_read(soft_watchdog_warn) == true) + if (__this_cpu_read(soft_watchdog_warn) == true) { + /* + * When multiple processes are causing softlockups the + * softlockup detector only warns on the first one + * because the code relies on a full quiet cycle to + * re-arm. The second process prevents the quiet cycle + * and never gets reported. Use task pointers to detect + * this. + */ + if (__this_cpu_read(softlockup_task_ptr_saved) != + current) { + __this_cpu_write(soft_watchdog_warn, false); + __touch_watchdog(); + } return HRTIMER_RESTART; + } if (softlockup_all_cpu_backtrace) { /* Prevent multiple soft-lockup reports if one cpu is already @@ -345,9 +384,10 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) } } - printk(KERN_EMERG "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", + pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", smp_processor_id(), duration, current->comm, task_pid_nr(current)); + __this_cpu_write(softlockup_task_ptr_saved, current); print_modules(); print_irqtrace_events(current); if (regs) @@ -366,6 +406,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) smp_mb__after_atomic(); } + add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); if (softlockup_panic) panic("softlockup: hung tasks"); __this_cpu_write(soft_watchdog_warn, true); @@ -384,7 +425,7 @@ static void watchdog_set_prio(unsigned int policy, unsigned int prio) static void watchdog_enable(unsigned int cpu) { - struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); + struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); /* kick off the timer for the hardlockup detector */ hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); @@ -404,7 +445,7 @@ static void watchdog_enable(unsigned int cpu) static void watchdog_disable(unsigned int cpu) { - struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); + struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); watchdog_set_prio(SCHED_NORMAL, 0); hrtimer_cancel(hrtimer); @@ -451,6 +492,15 @@ static int watchdog_nmi_enable(unsigned int cpu) struct perf_event_attr *wd_attr; struct perf_event *event = per_cpu(watchdog_ev, cpu); + /* + * Some kernels need to default hard lockup detection to + * 'disabled', for example a guest on a hypervisor. + */ + if (!watchdog_hardlockup_detector_is_enabled()) { + event = ERR_PTR(-ENOENT); + goto handle_err; + } + /* is it already setup and enabled? */ if (event && event->state > PERF_EVENT_STATE_OFF) goto out; @@ -465,6 +515,7 @@ static int watchdog_nmi_enable(unsigned int cpu) /* Try to register using hardware perf events */ event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL); +handle_err: /* save cpu0 error for future comparision */ if (cpu == 0 && IS_ERR(event)) cpu0_err = PTR_ERR(event); @@ -484,7 +535,7 @@ static int watchdog_nmi_enable(unsigned int cpu) if (PTR_ERR(event) == -EOPNOTSUPP) pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu); else if (PTR_ERR(event) == -ENOENT) - pr_warning("disabled (cpu%i): hardware events not enabled\n", + pr_warn("disabled (cpu%i): hardware events not enabled\n", cpu); else pr_err("disabled (cpu%i): unable to create perf event: %ld\n", @@ -511,7 +562,10 @@ static void watchdog_nmi_disable(unsigned int cpu) /* should be in cleanup, but blocks oprofile */ perf_event_release_kernel(event); } - return; + if (cpu == 0) { + /* watchdog_nmi_enable() expects this to be zero initially. */ + cpu0_err = 0; + } } #else static int watchdog_nmi_enable(unsigned int cpu) { return 0; } @@ -531,7 +585,7 @@ static struct smp_hotplug_thread watchdog_threads = { static void restart_watchdog_hrtimer(void *info) { - struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); + struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); int ret; /* @@ -607,11 +661,13 @@ int proc_dowatchdog(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { int err, old_thresh, old_enabled; + bool old_hardlockup; static DEFINE_MUTEX(watchdog_proc_mutex); mutex_lock(&watchdog_proc_mutex); old_thresh = ACCESS_ONCE(watchdog_thresh); old_enabled = ACCESS_ONCE(watchdog_user_enabled); + old_hardlockup = watchdog_hardlockup_detector_is_enabled(); err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); if (err || !write) @@ -623,15 +679,22 @@ int proc_dowatchdog(struct ctl_table *table, int write, * disabled. The 'watchdog_running' variable check in * watchdog_*_all_cpus() function takes care of this. */ - if (watchdog_user_enabled && watchdog_thresh) + if (watchdog_user_enabled && watchdog_thresh) { + /* + * Prevent a change in watchdog_thresh accidentally overriding + * the enablement of the hardlockup detector. + */ + if (watchdog_user_enabled != old_enabled) + watchdog_enable_hardlockup_detector(true); err = watchdog_enable_all_cpus(old_thresh != watchdog_thresh); - else + } else watchdog_disable_all_cpus(); /* Restore old values on failure */ if (err) { watchdog_thresh = old_thresh; watchdog_user_enabled = old_enabled; + watchdog_enable_hardlockup_detector(old_hardlockup); } out: mutex_unlock(&watchdog_proc_mutex); |