Merge branch 'core/softlockup' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core/softlockup' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: softlockup: make DETECT_HUNG_TASK default depend on DETECT_SOFTLOCKUP softlockup: move 'one' to the softlockup section in sysctl.c softlockup: ensure the task has been switched out once softlockup: remove timestamp checking from hung_task softlockup: convert read_lock in hung_task to rcu_read_lock softlockup: check all tasks in hung_task softlockup: remove unused definition for spawn_softlockup_task softlockup: fix potential race in hung_task when resetting timeout softlockup: fix to allow compiling with !DETECT_HUNG_TASK softlockup: decouple hung tasks check from softlockup detection
This commit is contained in:
Linus Torvalds
Коммит
1551260d1f
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@ -300,17 +300,11 @@ extern int proc_dosoftlockup_thresh(struct ctl_table *table, int write,
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struct file *filp, void __user *buffer,
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size_t *lenp, loff_t *ppos);
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extern unsigned int softlockup_panic;
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extern unsigned long sysctl_hung_task_check_count;
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extern unsigned long sysctl_hung_task_timeout_secs;
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extern unsigned long sysctl_hung_task_warnings;
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extern int softlockup_thresh;
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#else
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static inline void softlockup_tick(void)
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{
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}
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static inline void spawn_softlockup_task(void)
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{
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}
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static inline void touch_softlockup_watchdog(void)
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{
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}
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@ -319,6 +313,15 @@ static inline void touch_all_softlockup_watchdogs(void)
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}
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#endif
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#ifdef CONFIG_DETECT_HUNG_TASK
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extern unsigned int sysctl_hung_task_panic;
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extern unsigned long sysctl_hung_task_check_count;
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extern unsigned long sysctl_hung_task_timeout_secs;
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extern unsigned long sysctl_hung_task_warnings;
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extern int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
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struct file *filp, void __user *buffer,
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size_t *lenp, loff_t *ppos);
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#endif
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/* Attach to any functions which should be ignored in wchan output. */
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#define __sched __attribute__((__section__(".sched.text")))
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@ -1255,9 +1258,8 @@ struct task_struct {
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/* ipc stuff */
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struct sysv_sem sysvsem;
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#endif
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#ifdef CONFIG_DETECT_SOFTLOCKUP
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#ifdef CONFIG_DETECT_HUNG_TASK
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/* hung task detection */
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unsigned long last_switch_timestamp;
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unsigned long last_switch_count;
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#endif
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/* CPU-specific state of this task */
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@ -74,6 +74,7 @@ obj-$(CONFIG_AUDIT_TREE) += audit_tree.o
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obj-$(CONFIG_KPROBES) += kprobes.o
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obj-$(CONFIG_KGDB) += kgdb.o
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obj-$(CONFIG_DETECT_SOFTLOCKUP) += softlockup.o
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obj-$(CONFIG_DETECT_HUNG_TASK) += hung_task.o
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obj-$(CONFIG_GENERIC_HARDIRQS) += irq/
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obj-$(CONFIG_SECCOMP) += seccomp.o
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obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
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@ -645,6 +645,9 @@ static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
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tsk->min_flt = tsk->maj_flt = 0;
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tsk->nvcsw = tsk->nivcsw = 0;
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#ifdef CONFIG_DETECT_HUNG_TASK
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tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
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#endif
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tsk->mm = NULL;
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tsk->active_mm = NULL;
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@ -1032,11 +1035,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
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p->default_timer_slack_ns = current->timer_slack_ns;
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#ifdef CONFIG_DETECT_SOFTLOCKUP
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p->last_switch_count = 0;
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p->last_switch_timestamp = 0;
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#endif
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task_io_accounting_init(&p->ioac);
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acct_clear_integrals(p);
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@ -0,0 +1,217 @@
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/*
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* Detect Hung Task
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*
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* kernel/hung_task.c - kernel thread for detecting tasks stuck in D state
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*
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*/
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#include <linux/mm.h>
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#include <linux/cpu.h>
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#include <linux/nmi.h>
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#include <linux/init.h>
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#include <linux/delay.h>
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#include <linux/freezer.h>
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#include <linux/kthread.h>
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#include <linux/lockdep.h>
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#include <linux/module.h>
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#include <linux/sysctl.h>
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/*
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* The number of tasks checked:
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*/
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unsigned long __read_mostly sysctl_hung_task_check_count = PID_MAX_LIMIT;
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/*
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* Limit number of tasks checked in a batch.
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*
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* This value controls the preemptibility of khungtaskd since preemption
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* is disabled during the critical section. It also controls the size of
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* the RCU grace period. So it needs to be upper-bound.
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*/
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#define HUNG_TASK_BATCHING 1024
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/*
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* Zero means infinite timeout - no checking done:
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*/
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unsigned long __read_mostly sysctl_hung_task_timeout_secs = 120;
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unsigned long __read_mostly sysctl_hung_task_warnings = 10;
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static int __read_mostly did_panic;
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static struct task_struct *watchdog_task;
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/*
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* Should we panic (and reboot, if panic_timeout= is set) when a
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* hung task is detected:
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*/
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unsigned int __read_mostly sysctl_hung_task_panic =
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CONFIG_BOOTPARAM_HUNG_TASK_PANIC_VALUE;
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static int __init hung_task_panic_setup(char *str)
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{
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sysctl_hung_task_panic = simple_strtoul(str, NULL, 0);
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return 1;
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}
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__setup("hung_task_panic=", hung_task_panic_setup);
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static int
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hung_task_panic(struct notifier_block *this, unsigned long event, void *ptr)
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{
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did_panic = 1;
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return NOTIFY_DONE;
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}
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static struct notifier_block panic_block = {
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.notifier_call = hung_task_panic,
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};
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static void check_hung_task(struct task_struct *t, unsigned long timeout)
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{
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unsigned long switch_count = t->nvcsw + t->nivcsw;
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/*
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* Ensure the task is not frozen.
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* Also, when a freshly created task is scheduled once, changes
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* its state to TASK_UNINTERRUPTIBLE without having ever been
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* switched out once, it musn't be checked.
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*/
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if (unlikely(t->flags & PF_FROZEN || !switch_count))
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return;
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if (switch_count != t->last_switch_count) {
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t->last_switch_count = switch_count;
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return;
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}
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if (!sysctl_hung_task_warnings)
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return;
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sysctl_hung_task_warnings--;
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/*
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* Ok, the task did not get scheduled for more than 2 minutes,
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* complain:
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*/
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printk(KERN_ERR "INFO: task %s:%d blocked for more than "
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"%ld seconds.\n", t->comm, t->pid, timeout);
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printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
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" disables this message.\n");
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sched_show_task(t);
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__debug_show_held_locks(t);
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touch_nmi_watchdog();
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if (sysctl_hung_task_panic)
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panic("hung_task: blocked tasks");
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}
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/*
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* To avoid extending the RCU grace period for an unbounded amount of time,
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* periodically exit the critical section and enter a new one.
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*
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* For preemptible RCU it is sufficient to call rcu_read_unlock in order
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* exit the grace period. For classic RCU, a reschedule is required.
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*/
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static void rcu_lock_break(struct task_struct *g, struct task_struct *t)
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{
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get_task_struct(g);
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get_task_struct(t);
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rcu_read_unlock();
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cond_resched();
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rcu_read_lock();
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put_task_struct(t);
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put_task_struct(g);
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}
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/*
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* Check whether a TASK_UNINTERRUPTIBLE does not get woken up for
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* a really long time (120 seconds). If that happens, print out
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* a warning.
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*/
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static void check_hung_uninterruptible_tasks(unsigned long timeout)
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{
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int max_count = sysctl_hung_task_check_count;
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int batch_count = HUNG_TASK_BATCHING;
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struct task_struct *g, *t;
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/*
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* If the system crashed already then all bets are off,
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* do not report extra hung tasks:
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*/
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if (test_taint(TAINT_DIE) || did_panic)
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return;
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rcu_read_lock();
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do_each_thread(g, t) {
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if (!--max_count)
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goto unlock;
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if (!--batch_count) {
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batch_count = HUNG_TASK_BATCHING;
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rcu_lock_break(g, t);
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/* Exit if t or g was unhashed during refresh. */
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if (t->state == TASK_DEAD || g->state == TASK_DEAD)
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goto unlock;
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}
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/* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
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if (t->state == TASK_UNINTERRUPTIBLE)
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check_hung_task(t, timeout);
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} while_each_thread(g, t);
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unlock:
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rcu_read_unlock();
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}
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static unsigned long timeout_jiffies(unsigned long timeout)
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{
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/* timeout of 0 will disable the watchdog */
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return timeout ? timeout * HZ : MAX_SCHEDULE_TIMEOUT;
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}
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/*
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* Process updating of timeout sysctl
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*/
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int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
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struct file *filp, void __user *buffer,
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size_t *lenp, loff_t *ppos)
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{
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int ret;
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ret = proc_doulongvec_minmax(table, write, filp, buffer, lenp, ppos);
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if (ret || !write)
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goto out;
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wake_up_process(watchdog_task);
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out:
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return ret;
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}
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/*
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* kthread which checks for tasks stuck in D state
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*/
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static int watchdog(void *dummy)
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{
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set_user_nice(current, 0);
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for ( ; ; ) {
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unsigned long timeout = sysctl_hung_task_timeout_secs;
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while (schedule_timeout_interruptible(timeout_jiffies(timeout)))
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timeout = sysctl_hung_task_timeout_secs;
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check_hung_uninterruptible_tasks(timeout);
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}
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return 0;
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}
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static int __init hung_task_init(void)
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{
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atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
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watchdog_task = kthread_run(watchdog, NULL, "khungtaskd");
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return 0;
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}
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module_init(hung_task_init);
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@ -165,98 +165,12 @@ void softlockup_tick(void)
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panic("softlockup: hung tasks");
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}
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/*
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* Have a reasonable limit on the number of tasks checked:
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*/
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unsigned long __read_mostly sysctl_hung_task_check_count = 1024;
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/*
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* Zero means infinite timeout - no checking done:
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*/
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unsigned long __read_mostly sysctl_hung_task_timeout_secs = 480;
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unsigned long __read_mostly sysctl_hung_task_warnings = 10;
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/*
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* Only do the hung-tasks check on one CPU:
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*/
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static int check_cpu __read_mostly = -1;
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static void check_hung_task(struct task_struct *t, unsigned long now)
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{
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unsigned long switch_count = t->nvcsw + t->nivcsw;
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if (t->flags & PF_FROZEN)
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return;
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if (switch_count != t->last_switch_count || !t->last_switch_timestamp) {
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t->last_switch_count = switch_count;
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t->last_switch_timestamp = now;
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return;
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}
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if ((long)(now - t->last_switch_timestamp) <
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sysctl_hung_task_timeout_secs)
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return;
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if (!sysctl_hung_task_warnings)
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return;
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sysctl_hung_task_warnings--;
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|
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/*
|
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* Ok, the task did not get scheduled for more than 2 minutes,
|
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* complain:
|
||||
*/
|
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printk(KERN_ERR "INFO: task %s:%d blocked for more than "
|
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"%ld seconds.\n", t->comm, t->pid,
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sysctl_hung_task_timeout_secs);
|
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printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
|
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" disables this message.\n");
|
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sched_show_task(t);
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__debug_show_held_locks(t);
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|
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t->last_switch_timestamp = now;
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touch_nmi_watchdog();
|
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|
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if (softlockup_panic)
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panic("softlockup: blocked tasks");
|
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}
|
||||
|
||||
/*
|
||||
* Check whether a TASK_UNINTERRUPTIBLE does not get woken up for
|
||||
* a really long time (120 seconds). If that happens, print out
|
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* a warning.
|
||||
*/
|
||||
static void check_hung_uninterruptible_tasks(int this_cpu)
|
||||
{
|
||||
int max_count = sysctl_hung_task_check_count;
|
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unsigned long now = get_timestamp(this_cpu);
|
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struct task_struct *g, *t;
|
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|
||||
/*
|
||||
* If the system crashed already then all bets are off,
|
||||
* do not report extra hung tasks:
|
||||
*/
|
||||
if (test_taint(TAINT_DIE) || did_panic)
|
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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);
|
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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))
|
||||
|
|
|
|||
|
|
@ -814,6 +814,19 @@ 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",
|
||||
|
|
@ -829,7 +842,7 @@ 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 DETECT_SOFTLOCKUP
|
||||
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
|
||||
|
|
|
|||
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