From d63285e94af3ade4fa8b10b0d9a22bcf72baf2f9 Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Fri, 11 Oct 2013 21:39:25 -0300 Subject: pvclock: detect watchdog reset at pvclock read Implement reset of kernel watchdogs at pvclock read time. This avoids adding special code to every watchdog. This is possible for watchdogs which measure time based on sched_clock() or ktime_get() variants. Suggested by Don Zickus. Acked-by: Don Zickus Acked-by: Paolo Bonzini Signed-off-by: Marcelo Tosatti Signed-off-by: Gleb Natapov --- arch/x86/kernel/kvmclock.c | 1 + arch/x86/kernel/pvclock.c | 12 ++++++++++++ 2 files changed, 13 insertions(+) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index 1570e074134..e6041094ff2 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -139,6 +139,7 @@ bool kvm_check_and_clear_guest_paused(void) src = &hv_clock[cpu].pvti; if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) { src->flags &= ~PVCLOCK_GUEST_STOPPED; + pvclock_touch_watchdogs(); ret = true; } diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c index a16bae3f83b..6279928c0a7 100644 --- a/arch/x86/kernel/pvclock.c +++ b/arch/x86/kernel/pvclock.c @@ -43,6 +43,13 @@ unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src) return pv_tsc_khz; } +void pvclock_touch_watchdogs(void) +{ + touch_softlockup_watchdog_sync(); + clocksource_touch_watchdog(); + rcu_cpu_stall_reset(); +} + static atomic64_t last_value = ATOMIC64_INIT(0); void pvclock_resume(void) @@ -74,6 +81,11 @@ cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src) version = __pvclock_read_cycles(src, &ret, &flags); } while ((src->version & 1) || version != src->version); + if (unlikely((flags & PVCLOCK_GUEST_STOPPED) != 0)) { + src->flags &= ~PVCLOCK_GUEST_STOPPED; + pvclock_touch_watchdogs(); + } + if ((valid_flags & PVCLOCK_TSC_STABLE_BIT) && (flags & PVCLOCK_TSC_STABLE_BIT)) return ret; -- cgit v1.2.3-70-g09d2 From 8b414521bc5375ae8ba18c083af95d44b8da0d04 Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Fri, 11 Oct 2013 21:39:26 -0300 Subject: hung_task: add method to reset detector In certain occasions it is possible for a hung task detector positive to be false: continuation from a paused VM, for example. Add a method to reset detection, similar as is done with other kernel watchdogs. Acked-by: Don Zickus Acked-by: Paolo Bonzini Signed-off-by: Marcelo Tosatti Signed-off-by: Gleb Natapov --- arch/x86/kernel/pvclock.c | 1 + include/linux/sched.h | 8 ++++++++ kernel/hung_task.c | 11 +++++++++++ 3 files changed, 20 insertions(+) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c index 6279928c0a7..2f355d229a5 100644 --- a/arch/x86/kernel/pvclock.c +++ b/arch/x86/kernel/pvclock.c @@ -48,6 +48,7 @@ void pvclock_touch_watchdogs(void) touch_softlockup_watchdog_sync(); clocksource_touch_watchdog(); rcu_cpu_stall_reset(); + reset_hung_task_detector(); } static atomic64_t last_value = ATOMIC64_INIT(0); diff --git a/include/linux/sched.h b/include/linux/sched.h index 6682da36b29..7bb4b4a2a10 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -285,6 +285,14 @@ static inline void lockup_detector_init(void) } #endif +#ifdef CONFIG_DETECT_HUNG_TASK +void reset_hung_task_detector(void); +#else +static inline void reset_hung_task_detector(void) +{ +} +#endif + /* Attach to any functions which should be ignored in wchan output. */ #define __sched __attribute__((__section__(".sched.text"))) diff --git a/kernel/hung_task.c b/kernel/hung_task.c index 3e97fb126e6..dfdf51534b3 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -203,6 +203,14 @@ int proc_dohung_task_timeout_secs(struct ctl_table *table, int write, return ret; } +static atomic_t reset_hung_task = ATOMIC_INIT(0); + +void reset_hung_task_detector(void) +{ + atomic_set(&reset_hung_task, 1); +} +EXPORT_SYMBOL_GPL(reset_hung_task_detector); + /* * kthread which checks for tasks stuck in D state */ @@ -216,6 +224,9 @@ static int watchdog(void *dummy) while (schedule_timeout_interruptible(timeout_jiffies(timeout))) timeout = sysctl_hung_task_timeout_secs; + if (atomic_xchg(&reset_hung_task, 0)) + continue; + check_hung_uninterruptible_tasks(timeout); } -- cgit v1.2.3-70-g09d2