softlockup: decouple hung tasks check from softlockup detection
Decoupling allows: * hung tasks check to happen at very low priority * hung tasks check and softlockup to be enabled/disabled independently at compile and/or run-time * individual panic settings to be enabled disabled independently at compile and/or run-time * softlockup threshold to be reduced without increasing hung tasks poll frequency (hung task check is expensive relative to softlock watchdog) * hung task check to be zero over-head when disabled at run-time Signed-off-by: Mandeep Singh Baines <msb@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Mandeep Singh Baines
Ingo Molnar
Родитель
c903ff8379
Коммит
e162b39a36
|
|
@ -297,9 +297,6 @@ extern int proc_dosoftlockup_thresh(struct ctl_table *table, int write,
|
|||
struct file *filp, void __user *buffer,
|
||||
size_t *lenp, loff_t *ppos);
|
||||
extern unsigned int softlockup_panic;
|
||||
extern unsigned long sysctl_hung_task_check_count;
|
||||
extern unsigned long sysctl_hung_task_timeout_secs;
|
||||
extern unsigned long sysctl_hung_task_warnings;
|
||||
extern int softlockup_thresh;
|
||||
#else
|
||||
static inline void softlockup_tick(void)
|
||||
|
|
@ -316,6 +313,15 @@ static inline void touch_all_softlockup_watchdogs(void)
|
|||
}
|
||||
#endif
|
||||
|
||||
#ifdef CONFIG_DETECT_HUNG_TASK
|
||||
extern unsigned int sysctl_hung_task_panic;
|
||||
extern unsigned long sysctl_hung_task_check_count;
|
||||
extern unsigned long sysctl_hung_task_timeout_secs;
|
||||
extern unsigned long sysctl_hung_task_warnings;
|
||||
extern int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
|
||||
struct file *filp, void __user *buffer,
|
||||
size_t *lenp, loff_t *ppos);
|
||||
#endif
|
||||
|
||||
/* Attach to any functions which should be ignored in wchan output. */
|
||||
#define __sched __attribute__((__section__(".sched.text")))
|
||||
|
|
@ -1236,7 +1242,7 @@ struct task_struct {
|
|||
/* ipc stuff */
|
||||
struct sysv_sem sysvsem;
|
||||
#endif
|
||||
#ifdef CONFIG_DETECT_SOFTLOCKUP
|
||||
#ifdef CONFIG_DETECT_HUNG_TASK
|
||||
/* hung task detection */
|
||||
unsigned long last_switch_timestamp;
|
||||
unsigned long last_switch_count;
|
||||
|
|
|
|||
|
|
@ -74,6 +74,7 @@ obj-$(CONFIG_AUDIT_TREE) += audit_tree.o
|
|||
obj-$(CONFIG_KPROBES) += kprobes.o
|
||||
obj-$(CONFIG_KGDB) += kgdb.o
|
||||
obj-$(CONFIG_DETECT_SOFTLOCKUP) += softlockup.o
|
||||
obj-$(CONFIG_DETECT_HUNG_TASK) += hung_task.o
|
||||
obj-$(CONFIG_GENERIC_HARDIRQS) += irq/
|
||||
obj-$(CONFIG_SECCOMP) += seccomp.o
|
||||
obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
|
||||
|
|
|
|||
|
|
@ -0,0 +1,198 @@
|
|||
/*
|
||||
* Detect Hung Task
|
||||
*
|
||||
* kernel/hung_task.c - kernel thread for detecting tasks stuck in D state
|
||||
*
|
||||
*/
|
||||
|
||||
#include <linux/mm.h>
|
||||
#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/module.h>
|
||||
#include <linux/sysctl.h>
|
||||
|
||||
/*
|
||||
* Have a reasonable limit on the number of tasks checked:
|
||||
*/
|
||||
unsigned long __read_mostly sysctl_hung_task_check_count = 1024;
|
||||
|
||||
/*
|
||||
* Zero means infinite timeout - no checking done:
|
||||
*/
|
||||
unsigned long __read_mostly sysctl_hung_task_timeout_secs = 120;
|
||||
static unsigned long __read_mostly hung_task_poll_jiffies;
|
||||
|
||||
unsigned long __read_mostly sysctl_hung_task_warnings = 10;
|
||||
|
||||
static int __read_mostly did_panic;
|
||||
|
||||
static struct task_struct *watchdog_task;
|
||||
|
||||
/*
|
||||
* Should we panic (and reboot, if panic_timeout= is set) when a
|
||||
* hung task is detected:
|
||||
*/
|
||||
unsigned int __read_mostly sysctl_hung_task_panic =
|
||||
CONFIG_BOOTPARAM_HUNG_TASK_PANIC_VALUE;
|
||||
|
||||
static int __init hung_task_panic_setup(char *str)
|
||||
{
|
||||
sysctl_hung_task_panic = simple_strtoul(str, NULL, 0);
|
||||
|
||||
return 1;
|
||||
}
|
||||
__setup("hung_task_panic=", hung_task_panic_setup);
|
||||
|
||||
static int
|
||||
hung_task_panic(struct notifier_block *this, unsigned long event, void *ptr)
|
||||
{
|
||||
did_panic = 1;
|
||||
|
||||
return NOTIFY_DONE;
|
||||
}
|
||||
|
||||
static struct notifier_block panic_block = {
|
||||
.notifier_call = hung_task_panic,
|
||||
};
|
||||
|
||||
/*
|
||||
* Returns seconds, approximately. We don't need nanosecond
|
||||
* resolution, and we don't need to waste time with a big divide when
|
||||
* 2^30ns == 1.074s.
|
||||
*/
|
||||
static unsigned long get_timestamp(void)
|
||||
{
|
||||
int this_cpu = raw_smp_processor_id();
|
||||
|
||||
return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */
|
||||
}
|
||||
|
||||
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)
|
||||
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();
|
||||
|
||||
if (sysctl_hung_task_panic)
|
||||
panic("hung_task: blocked tasks");
|
||||
}
|
||||
|
||||
/*
|
||||
* 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(void)
|
||||
{
|
||||
int max_count = sysctl_hung_task_check_count;
|
||||
unsigned long now = get_timestamp();
|
||||
struct task_struct *g, *t;
|
||||
|
||||
/*
|
||||
* If the system crashed already then all bets are off,
|
||||
* do not report extra hung tasks:
|
||||
*/
|
||||
if (test_taint(TAINT_DIE) || did_panic)
|
||||
return;
|
||||
|
||||
read_lock(&tasklist_lock);
|
||||
do_each_thread(g, t) {
|
||||
if (!--max_count)
|
||||
goto unlock;
|
||||
/* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
|
||||
if (t->state == TASK_UNINTERRUPTIBLE)
|
||||
check_hung_task(t, now);
|
||||
} while_each_thread(g, t);
|
||||
unlock:
|
||||
read_unlock(&tasklist_lock);
|
||||
}
|
||||
|
||||
static void update_poll_jiffies(void)
|
||||
{
|
||||
/* timeout of 0 will disable the watchdog */
|
||||
if (sysctl_hung_task_timeout_secs == 0)
|
||||
hung_task_poll_jiffies = MAX_SCHEDULE_TIMEOUT;
|
||||
else
|
||||
hung_task_poll_jiffies = sysctl_hung_task_timeout_secs * HZ / 2;
|
||||
}
|
||||
|
||||
/*
|
||||
* Process updating of timeout sysctl
|
||||
*/
|
||||
int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
|
||||
struct file *filp, void __user *buffer,
|
||||
size_t *lenp, loff_t *ppos)
|
||||
{
|
||||
int ret;
|
||||
|
||||
ret = proc_doulongvec_minmax(table, write, filp, buffer, lenp, ppos);
|
||||
|
||||
if (ret || !write)
|
||||
goto out;
|
||||
|
||||
update_poll_jiffies();
|
||||
|
||||
wake_up_process(watchdog_task);
|
||||
|
||||
out:
|
||||
return ret;
|
||||
}
|
||||
|
||||
/*
|
||||
* kthread which checks for tasks stuck in D state
|
||||
*/
|
||||
static int watchdog(void *dummy)
|
||||
{
|
||||
set_user_nice(current, 0);
|
||||
update_poll_jiffies();
|
||||
|
||||
for ( ; ; ) {
|
||||
while (schedule_timeout_interruptible(hung_task_poll_jiffies));
|
||||
check_hung_uninterruptible_tasks();
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int __init hung_task_init(void)
|
||||
{
|
||||
atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
|
||||
watchdog_task = kthread_run(watchdog, NULL, "khungtaskd");
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
module_init(hung_task_init);
|
||||
|
|
@ -165,98 +165,12 @@ void softlockup_tick(void)
|
|||
panic("softlockup: hung tasks");
|
||||
}
|
||||
|
||||
/*
|
||||
* Have a reasonable limit on the number of tasks checked:
|
||||
*/
|
||||
unsigned long __read_mostly sysctl_hung_task_check_count = 1024;
|
||||
|
||||
/*
|
||||
* Zero means infinite timeout - no checking done:
|
||||
*/
|
||||
unsigned long __read_mostly sysctl_hung_task_timeout_secs = 480;
|
||||
|
||||
unsigned long __read_mostly 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)
|
||||
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();
|
||||
|
||||
if (softlockup_panic)
|
||||
panic("softlockup: blocked tasks");
|
||||
}
|
||||
|
||||
/*
|
||||
* 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 (test_taint(TAINT_DIE) || did_panic)
|
||||
return;
|
||||
|
||||
read_lock(&tasklist_lock);
|
||||
do_each_thread(g, t) {
|
||||
if (!--max_count)
|
||||
goto unlock;
|
||||
/* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
|
||||
if (t->state == TASK_UNINTERRUPTIBLE)
|
||||
check_hung_task(t, now);
|
||||
} while_each_thread(g, t);
|
||||
unlock:
|
||||
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, ¶m);
|
||||
|
||||
|
|
@ -276,11 +190,6 @@ static int watchdog(void *__bind_cpu)
|
|||
if (kthread_should_stop())
|
||||
break;
|
||||
|
||||
if (this_cpu == check_cpu) {
|
||||
if (sysctl_hung_task_timeout_secs)
|
||||
check_hung_uninterruptible_tasks(this_cpu);
|
||||
}
|
||||
|
||||
set_current_state(TASK_INTERRUPTIBLE);
|
||||
}
|
||||
__set_current_state(TASK_RUNNING);
|
||||
|
|
@ -312,18 +221,9 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
|
|||
break;
|
||||
case CPU_ONLINE:
|
||||
case CPU_ONLINE_FROZEN:
|
||||
check_cpu = cpumask_any(cpu_online_mask);
|
||||
wake_up_process(per_cpu(watchdog_task, hotcpu));
|
||||
break;
|
||||
#ifdef CONFIG_HOTPLUG_CPU
|
||||
case CPU_DOWN_PREPARE:
|
||||
case CPU_DOWN_PREPARE_FROZEN:
|
||||
if (hotcpu == check_cpu) {
|
||||
/* Pick any other online cpu. */
|
||||
check_cpu = cpumask_any_but(cpu_online_mask, hotcpu);
|
||||
}
|
||||
break;
|
||||
|
||||
case CPU_UP_CANCELED:
|
||||
case CPU_UP_CANCELED_FROZEN:
|
||||
if (!per_cpu(watchdog_task, hotcpu))
|
||||
|
|
|
|||
|
|
@ -805,6 +805,19 @@ static struct ctl_table kern_table[] = {
|
|||
.extra1 = &neg_one,
|
||||
.extra2 = &sixty,
|
||||
},
|
||||
#endif
|
||||
#ifdef CONFIG_DETECT_HUNG_TASK
|
||||
{
|
||||
.ctl_name = CTL_UNNUMBERED,
|
||||
.procname = "hung_task_panic",
|
||||
.data = &sysctl_hung_task_panic,
|
||||
.maxlen = sizeof(int),
|
||||
.mode = 0644,
|
||||
.proc_handler = &proc_dointvec_minmax,
|
||||
.strategy = &sysctl_intvec,
|
||||
.extra1 = &zero,
|
||||
.extra2 = &one,
|
||||
},
|
||||
{
|
||||
.ctl_name = CTL_UNNUMBERED,
|
||||
.procname = "hung_task_check_count",
|
||||
|
|
@ -820,7 +833,7 @@ static struct ctl_table kern_table[] = {
|
|||
.data = &sysctl_hung_task_timeout_secs,
|
||||
.maxlen = sizeof(unsigned long),
|
||||
.mode = 0644,
|
||||
.proc_handler = &proc_doulongvec_minmax,
|
||||
.proc_handler = &proc_dohung_task_timeout_secs,
|
||||
.strategy = &sysctl_intvec,
|
||||
},
|
||||
{
|
||||
|
|
|
|||
|
|
@ -186,6 +186,44 @@ config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
|
|||
default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
|
||||
default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
|
||||
|
||||
config DETECT_HUNG_TASK
|
||||
bool "Detect Hung Tasks"
|
||||
depends on DEBUG_KERNEL
|
||||
default y
|
||||
help
|
||||
Say Y here to enable the kernel to detect "hung tasks",
|
||||
which are bugs that cause the task to be stuck in
|
||||
uninterruptible "D" state indefinitiley.
|
||||
|
||||
When a hung task is detected, the kernel will print the
|
||||
current stack trace (which you should report), but the
|
||||
task will stay in uninterruptible state. If lockdep is
|
||||
enabled then all held locks will also be reported. This
|
||||
feature has negligible overhead.
|
||||
|
||||
config BOOTPARAM_HUNG_TASK_PANIC
|
||||
bool "Panic (Reboot) On Hung Tasks"
|
||||
depends on DETECT_HUNG_TASK
|
||||
help
|
||||
Say Y here to enable the kernel to panic on "hung tasks",
|
||||
which are bugs that cause the kernel to leave a task stuck
|
||||
in uninterruptible "D" state.
|
||||
|
||||
The panic can be used in combination with panic_timeout,
|
||||
to cause the system to reboot automatically after a
|
||||
hung task has been detected. This feature is useful for
|
||||
high-availability systems that have uptime guarantees and
|
||||
where a hung tasks must be resolved ASAP.
|
||||
|
||||
Say N if unsure.
|
||||
|
||||
config BOOTPARAM_HUNG_TASK_PANIC_VALUE
|
||||
int
|
||||
depends on DETECT_HUNG_TASK
|
||||
range 0 1
|
||||
default 0 if !BOOTPARAM_HUNG_TASK_PANIC
|
||||
default 1 if BOOTPARAM_HUNG_TASK_PANIC
|
||||
|
||||
config SCHED_DEBUG
|
||||
bool "Collect scheduler debugging info"
|
||||
depends on DEBUG_KERNEL && PROC_FS
|
||||
|
|
|
|||
Загрузка…
Ссылка в новой задаче