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-rw-r--r--include/linux/nmi.h2
-rw-r--r--kernel/sysctl.c4
-rw-r--r--kernel/time/tick-sched.c15
-rw-r--r--kernel/watchdog.c113
4 files changed, 72 insertions, 62 deletions
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index db50840..6a45fb5 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -46,7 +46,7 @@ static inline bool trigger_all_cpu_backtrace(void)
#ifdef CONFIG_LOCKUP_DETECTOR
int hw_nmi_is_cpu_stuck(struct pt_regs *);
u64 hw_nmi_get_sample_period(int watchdog_thresh);
-extern int watchdog_enabled;
+extern int watchdog_user_enabled;
extern int watchdog_thresh;
struct ctl_table;
extern int proc_dowatchdog(struct ctl_table *, int ,
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 4ce13c3..5c9e33b 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -800,7 +800,7 @@ static struct ctl_table kern_table[] = {
#if defined(CONFIG_LOCKUP_DETECTOR)
{
.procname = "watchdog",
- .data = &watchdog_enabled,
+ .data = &watchdog_user_enabled,
.maxlen = sizeof (int),
.mode = 0644,
.proc_handler = proc_dowatchdog,
@@ -827,7 +827,7 @@ static struct ctl_table kern_table[] = {
},
{
.procname = "nmi_watchdog",
- .data = &watchdog_enabled,
+ .data = &watchdog_user_enabled,
.maxlen = sizeof (int),
.mode = 0644,
.proc_handler = proc_dowatchdog,
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 0cf1c14..6960172 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -178,6 +178,11 @@ static bool can_stop_full_tick(void)
*/
if (!sched_clock_stable) {
trace_tick_stop(0, "unstable sched clock\n");
+ /*
+ * Don't allow the user to think they can get
+ * full NO_HZ with this machine.
+ */
+ WARN_ONCE(1, "NO_HZ FULL will not work with unstable sched clock");
return false;
}
#endif
@@ -346,16 +351,6 @@ void __init tick_nohz_init(void)
}
cpu_notifier(tick_nohz_cpu_down_callback, 0);
-
- /* Make sure full dynticks CPU are also RCU nocbs */
- for_each_cpu(cpu, nohz_full_mask) {
- if (!rcu_is_nocb_cpu(cpu)) {
- pr_warning("NO_HZ: CPU %d is not RCU nocb: "
- "cleared from nohz_full range", cpu);
- cpumask_clear_cpu(cpu, nohz_full_mask);
- }
- }
-
cpulist_scnprintf(nohz_full_buf, sizeof(nohz_full_buf), nohz_full_mask);
pr_info("NO_HZ: Full dynticks CPUs: %s.\n", nohz_full_buf);
}
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 05039e3..1241d8c 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -29,9 +29,9 @@
#include <linux/kvm_para.h>
#include <linux/perf_event.h>
-int watchdog_enabled = 1;
+int watchdog_user_enabled = 1;
int __read_mostly watchdog_thresh = 10;
-static int __read_mostly watchdog_disabled;
+static int __read_mostly watchdog_running;
static u64 __read_mostly sample_period;
static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
@@ -63,7 +63,7 @@ static int __init hardlockup_panic_setup(char *str)
else if (!strncmp(str, "nopanic", 7))
hardlockup_panic = 0;
else if (!strncmp(str, "0", 1))
- watchdog_enabled = 0;
+ watchdog_user_enabled = 0;
return 1;
}
__setup("nmi_watchdog=", hardlockup_panic_setup);
@@ -82,7 +82,7 @@ __setup("softlockup_panic=", softlockup_panic_setup);
static int __init nowatchdog_setup(char *str)
{
- watchdog_enabled = 0;
+ watchdog_user_enabled = 0;
return 1;
}
__setup("nowatchdog", nowatchdog_setup);
@@ -90,7 +90,7 @@ __setup("nowatchdog", nowatchdog_setup);
/* deprecated */
static int __init nosoftlockup_setup(char *str)
{
- watchdog_enabled = 0;
+ watchdog_user_enabled = 0;
return 1;
}
__setup("nosoftlockup", nosoftlockup_setup);
@@ -158,7 +158,7 @@ void touch_all_softlockup_watchdogs(void)
#ifdef CONFIG_HARDLOCKUP_DETECTOR
void touch_nmi_watchdog(void)
{
- if (watchdog_enabled) {
+ if (watchdog_user_enabled) {
unsigned cpu;
for_each_present_cpu(cpu) {
@@ -347,11 +347,6 @@ static void watchdog_enable(unsigned int cpu)
hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
hrtimer->function = watchdog_timer_fn;
- if (!watchdog_enabled) {
- kthread_park(current);
- return;
- }
-
/* Enable the perf event */
watchdog_nmi_enable(cpu);
@@ -374,6 +369,11 @@ static void watchdog_disable(unsigned int cpu)
watchdog_nmi_disable(cpu);
}
+static void watchdog_cleanup(unsigned int cpu, bool online)
+{
+ watchdog_disable(cpu);
+}
+
static int watchdog_should_run(unsigned int cpu)
{
return __this_cpu_read(hrtimer_interrupts) !=
@@ -475,28 +475,40 @@ static int watchdog_nmi_enable(unsigned int cpu) { return 0; }
static void watchdog_nmi_disable(unsigned int cpu) { return; }
#endif /* CONFIG_HARDLOCKUP_DETECTOR */
-/* prepare/enable/disable routines */
-/* sysctl functions */
-#ifdef CONFIG_SYSCTL
-static void watchdog_enable_all_cpus(void)
+static struct smp_hotplug_thread watchdog_threads = {
+ .store = &softlockup_watchdog,
+ .thread_should_run = watchdog_should_run,
+ .thread_fn = watchdog,
+ .thread_comm = "watchdog/%u",
+ .setup = watchdog_enable,
+ .cleanup = watchdog_cleanup,
+ .park = watchdog_disable,
+ .unpark = watchdog_enable,
+};
+
+static int watchdog_enable_all_cpus(void)
{
- unsigned int cpu;
+ int err = 0;
- if (watchdog_disabled) {
- watchdog_disabled = 0;
- for_each_online_cpu(cpu)
- kthread_unpark(per_cpu(softlockup_watchdog, cpu));
+ if (!watchdog_running) {
+ err = smpboot_register_percpu_thread(&watchdog_threads);
+ if (err)
+ pr_err("Failed to create watchdog threads, disabled\n");
+ else
+ watchdog_running = 1;
}
+
+ return err;
}
+/* prepare/enable/disable routines */
+/* sysctl functions */
+#ifdef CONFIG_SYSCTL
static void watchdog_disable_all_cpus(void)
{
- unsigned int cpu;
-
- if (!watchdog_disabled) {
- watchdog_disabled = 1;
- for_each_online_cpu(cpu)
- kthread_park(per_cpu(softlockup_watchdog, cpu));
+ if (watchdog_running) {
+ watchdog_running = 0;
+ smpboot_unregister_percpu_thread(&watchdog_threads);
}
}
@@ -507,45 +519,48 @@ static void watchdog_disable_all_cpus(void)
int proc_dowatchdog(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
- int ret;
+ int err, old_thresh, old_enabled;
- if (watchdog_disabled < 0)
- return -ENODEV;
+ old_thresh = ACCESS_ONCE(watchdog_thresh);
+ old_enabled = ACCESS_ONCE(watchdog_user_enabled);
- ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
- if (ret || !write)
- return ret;
+ err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+ if (err || !write)
+ return err;
set_sample_period();
/*
* Watchdog threads shouldn't be enabled if they are
- * disabled. The 'watchdog_disabled' variable check in
+ * disabled. The 'watchdog_running' variable check in
* watchdog_*_all_cpus() function takes care of this.
*/
- if (watchdog_enabled && watchdog_thresh)
- watchdog_enable_all_cpus();
+ if (watchdog_user_enabled && watchdog_thresh)
+ err = watchdog_enable_all_cpus();
else
watchdog_disable_all_cpus();
- return ret;
+ /* Restore old values on failure */
+ if (err) {
+ watchdog_thresh = old_thresh;
+ watchdog_user_enabled = old_enabled;
+ }
+
+ return err;
}
#endif /* CONFIG_SYSCTL */
-static struct smp_hotplug_thread watchdog_threads = {
- .store = &softlockup_watchdog,
- .thread_should_run = watchdog_should_run,
- .thread_fn = watchdog,
- .thread_comm = "watchdog/%u",
- .setup = watchdog_enable,
- .park = watchdog_disable,
- .unpark = watchdog_enable,
-};
-
void __init lockup_detector_init(void)
{
set_sample_period();
- if (smpboot_register_percpu_thread(&watchdog_threads)) {
- pr_err("Failed to create watchdog threads, disabled\n");
- watchdog_disabled = -ENODEV;
+
+#ifdef CONFIG_NO_HZ_FULL
+ if (watchdog_user_enabled) {
+ watchdog_user_enabled = 0;
+ pr_warning("Disabled lockup detectors by default for full dynticks\n");
+ pr_warning("You can reactivate it with 'sysctl -w kernel.watchdog=1'\n");
}
+#endif
+
+ if (watchdog_user_enabled)
+ watchdog_enable_all_cpus();
}
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