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-rw-r--r--include/linux/debug_locks.h5
-rw-r--r--include/linux/sched.h10
-rw-r--r--kernel/fork.c5
-rw-r--r--kernel/lockdep.c12
-rw-r--r--kernel/sched.c4
-rw-r--r--kernel/softlockup.c114
-rw-r--r--kernel/sysctl.c27
7 files changed, 164 insertions, 13 deletions
diff --git a/include/linux/debug_locks.h b/include/linux/debug_locks.h
index 1678a5d..f4a5871 100644
--- a/include/linux/debug_locks.h
+++ b/include/linux/debug_locks.h
@@ -47,6 +47,7 @@ struct task_struct;
#ifdef CONFIG_LOCKDEP
extern void debug_show_all_locks(void);
+extern void __debug_show_held_locks(struct task_struct *task);
extern void debug_show_held_locks(struct task_struct *task);
extern void debug_check_no_locks_freed(const void *from, unsigned long len);
extern void debug_check_no_locks_held(struct task_struct *task);
@@ -55,6 +56,10 @@ static inline void debug_show_all_locks(void)
{
}
+static inline void __debug_show_held_locks(struct task_struct *task)
+{
+}
+
static inline void debug_show_held_locks(struct task_struct *task)
{
}
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 288245f..0846f1f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -258,12 +258,17 @@ extern void account_process_tick(struct task_struct *task, int user);
extern void update_process_times(int user);
extern void scheduler_tick(void);
+extern void sched_show_task(struct task_struct *p);
+
#ifdef CONFIG_DETECT_SOFTLOCKUP
extern void softlockup_tick(void);
extern void spawn_softlockup_task(void);
extern void touch_softlockup_watchdog(void);
extern void touch_all_softlockup_watchdogs(void);
extern int softlockup_thresh;
+extern unsigned long sysctl_hung_task_check_count;
+extern unsigned long sysctl_hung_task_timeout_secs;
+extern long sysctl_hung_task_warnings;
#else
static inline void softlockup_tick(void)
{
@@ -1041,6 +1046,11 @@ struct task_struct {
/* ipc stuff */
struct sysv_sem sysvsem;
#endif
+#ifdef CONFIG_DETECT_SOFTLOCKUP
+/* hung task detection */
+ unsigned long last_switch_timestamp;
+ unsigned long last_switch_count;
+#endif
/* CPU-specific state of this task */
struct thread_struct thread;
/* filesystem information */
diff --git a/kernel/fork.c b/kernel/fork.c
index 8dd8ff2..09c0b90 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1059,6 +1059,11 @@ static struct task_struct *copy_process(unsigned long clone_flags,
p->prev_utime = cputime_zero;
p->prev_stime = cputime_zero;
+#ifdef CONFIG_DETECT_SOFTLOCKUP
+ p->last_switch_count = 0;
+ p->last_switch_timestamp = 0;
+#endif
+
#ifdef CONFIG_TASK_XACCT
p->rchar = 0; /* I/O counter: bytes read */
p->wchar = 0; /* I/O counter: bytes written */
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index e2c07ece..3574379 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -3206,7 +3206,11 @@ retry:
EXPORT_SYMBOL_GPL(debug_show_all_locks);
-void debug_show_held_locks(struct task_struct *task)
+/*
+ * Careful: only use this function if you are sure that
+ * the task cannot run in parallel!
+ */
+void __debug_show_held_locks(struct task_struct *task)
{
if (unlikely(!debug_locks)) {
printk("INFO: lockdep is turned off.\n");
@@ -3214,6 +3218,12 @@ void debug_show_held_locks(struct task_struct *task)
}
lockdep_print_held_locks(task);
}
+EXPORT_SYMBOL_GPL(__debug_show_held_locks);
+
+void debug_show_held_locks(struct task_struct *task)
+{
+ __debug_show_held_locks(task);
+}
EXPORT_SYMBOL_GPL(debug_show_held_locks);
diff --git a/kernel/sched.c b/kernel/sched.c
index c0e2db6..5b3d465 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4945,7 +4945,7 @@ out_unlock:
static const char stat_nam[] = "RSDTtZX";
-static void show_task(struct task_struct *p)
+void sched_show_task(struct task_struct *p)
{
unsigned long free = 0;
unsigned state;
@@ -4998,7 +4998,7 @@ void show_state_filter(unsigned long state_filter)
*/
touch_nmi_watchdog();
if (!state_filter || (p->state & state_filter))
- show_task(p);
+ sched_show_task(p);
} while_each_thread(g, p);
touch_all_softlockup_watchdogs();
diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index 11df812..02f0ad5 100644
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -8,6 +8,7 @@
*/
#include <linux/mm.h>
#include <linux/cpu.h>
+#include <linux/nmi.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/freezer.h>
@@ -24,7 +25,7 @@ static DEFINE_PER_CPU(unsigned long, print_timestamp);
static DEFINE_PER_CPU(struct task_struct *, watchdog_task);
static int did_panic;
-int softlockup_thresh = 10;
+int softlockup_thresh = 60;
static int
softlock_panic(struct notifier_block *this, unsigned long event, void *ptr)
@@ -45,7 +46,7 @@ static struct notifier_block panic_block = {
*/
static unsigned long get_timestamp(int this_cpu)
{
- return cpu_clock(this_cpu) >> 30; /* 2^30 ~= 10^9 */
+ return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */
}
void touch_softlockup_watchdog(void)
@@ -100,11 +101,7 @@ void softlockup_tick(void)
now = get_timestamp(this_cpu);
- /* Wake up the high-prio watchdog task every second: */
- if (now > (touch_timestamp + 1))
- wake_up_process(per_cpu(watchdog_task, this_cpu));
-
- /* Warn about unreasonable 10+ seconds delays: */
+ /* Warn about unreasonable delays: */
if (now <= (touch_timestamp + softlockup_thresh))
return;
@@ -122,11 +119,93 @@ void softlockup_tick(void)
}
/*
+ * Have a reasonable limit on the number of tasks checked:
+ */
+unsigned long sysctl_hung_task_check_count = 1024;
+
+/*
+ * Zero means infinite timeout - no checking done:
+ */
+unsigned long sysctl_hung_task_timeout_secs = 120;
+
+long sysctl_hung_task_warnings = 10;
+
+/*
+ * Only do the hung-tasks check on one CPU:
+ */
+static int check_cpu __read_mostly = -1;
+
+static void check_hung_task(struct task_struct *t, unsigned long now)
+{
+ unsigned long switch_count = t->nvcsw + t->nivcsw;
+
+ if (t->flags & PF_FROZEN)
+ return;
+
+ if (switch_count != t->last_switch_count || !t->last_switch_timestamp) {
+ t->last_switch_count = switch_count;
+ t->last_switch_timestamp = now;
+ return;
+ }
+ if ((long)(now - t->last_switch_timestamp) <
+ sysctl_hung_task_timeout_secs)
+ return;
+ if (sysctl_hung_task_warnings < 0)
+ return;
+ sysctl_hung_task_warnings--;
+
+ /*
+ * Ok, the task did not get scheduled for more than 2 minutes,
+ * complain:
+ */
+ printk(KERN_ERR "INFO: task %s:%d blocked for more than "
+ "%ld seconds.\n", t->comm, t->pid,
+ sysctl_hung_task_timeout_secs);
+ printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
+ " disables this message.\n");
+ sched_show_task(t);
+ __debug_show_held_locks(t);
+
+ t->last_switch_timestamp = now;
+ touch_nmi_watchdog();
+}
+
+/*
+ * Check whether a TASK_UNINTERRUPTIBLE does not get woken up for
+ * a really long time (120 seconds). If that happens, print out
+ * a warning.
+ */
+static void check_hung_uninterruptible_tasks(int this_cpu)
+{
+ int max_count = sysctl_hung_task_check_count;
+ unsigned long now = get_timestamp(this_cpu);
+ struct task_struct *g, *t;
+
+ /*
+ * If the system crashed already then all bets are off,
+ * do not report extra hung tasks:
+ */
+ if ((tainted & TAINT_DIE) || did_panic)
+ return;
+
+ read_lock(&tasklist_lock);
+ do_each_thread(g, t) {
+ if (!--max_count)
+ break;
+ if (t->state & TASK_UNINTERRUPTIBLE)
+ check_hung_task(t, now);
+ } while_each_thread(g, t);
+
+ read_unlock(&tasklist_lock);
+}
+
+/*
* The watchdog thread - runs every second and touches the timestamp.
*/
static int watchdog(void *__bind_cpu)
{
struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
+ int this_cpu = (long)__bind_cpu;
sched_setscheduler(current, SCHED_FIFO, &param);
@@ -135,13 +214,18 @@ static int watchdog(void *__bind_cpu)
/*
* Run briefly once per second to reset the softlockup timestamp.
- * If this gets delayed for more than 10 seconds then the
+ * If this gets delayed for more than 60 seconds then the
* debug-printout triggers in softlockup_tick().
*/
while (!kthread_should_stop()) {
- set_current_state(TASK_INTERRUPTIBLE);
touch_softlockup_watchdog();
- schedule();
+ msleep_interruptible(10000);
+
+ if (this_cpu != check_cpu)
+ continue;
+
+ if (sysctl_hung_task_timeout_secs)
+ check_hung_uninterruptible_tasks(this_cpu);
}
return 0;
@@ -171,6 +255,7 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
break;
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
+ check_cpu = any_online_cpu(cpu_online_map);
wake_up_process(per_cpu(watchdog_task, hotcpu));
break;
#ifdef CONFIG_HOTPLUG_CPU
@@ -181,6 +266,15 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
/* Unbind so it can run. Fall thru. */
kthread_bind(per_cpu(watchdog_task, hotcpu),
any_online_cpu(cpu_online_map));
+ case CPU_DOWN_PREPARE:
+ case CPU_DOWN_PREPARE_FROZEN:
+ if (hotcpu == check_cpu) {
+ cpumask_t temp_cpu_online_map = cpu_online_map;
+
+ cpu_clear(hotcpu, temp_cpu_online_map);
+ check_cpu = any_online_cpu(temp_cpu_online_map);
+ }
+ break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
p = per_cpu(watchdog_task, hotcpu);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index c95f3ed..96f31c1 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -753,6 +753,33 @@ static struct ctl_table kern_table[] = {
.extra1 = &one,
.extra2 = &sixty,
},
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "hung_task_check_count",
+ .data = &sysctl_hung_task_check_count,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec_minmax,
+ .strategy = &sysctl_intvec,
+ },
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "hung_task_timeout_secs",
+ .data = &sysctl_hung_task_timeout_secs,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec_minmax,
+ .strategy = &sysctl_intvec,
+ },
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "hung_task_warnings",
+ .data = &sysctl_hung_task_warnings,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec_minmax,
+ .strategy = &sysctl_intvec,
+ },
#endif
#ifdef CONFIG_COMPAT
{
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