int id; /* I: pool ID */
unsigned int flags; /* X: flags */
+ unsigned long watchdog_ts; /* L: watchdog timestamp */
+
struct list_head worklist; /* L: list of pending works */
int nr_workers; /* L: total number of workers */
struct pool_workqueue *pwq = get_work_pwq(work);
trace_workqueue_activate_work(work);
+ if (list_empty(&pwq->pool->worklist))
+ pwq->pool->watchdog_ts = jiffies;
move_linked_works(work, &pwq->pool->worklist, NULL);
__clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
pwq->nr_active++;
trace_workqueue_activate_work(work);
pwq->nr_active++;
worklist = &pwq->pool->worklist;
+ if (list_empty(worklist))
+ pwq->pool->watchdog_ts = jiffies;
} else {
work_flags |= WORK_STRUCT_DELAYED;
worklist = &pwq->delayed_works;
list_first_entry(&pool->worklist,
struct work_struct, entry);
+ pool->watchdog_ts = jiffies;
+
if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
/* optimization path, not strictly necessary */
process_one_work(worker, work);
struct pool_workqueue, mayday_node);
struct worker_pool *pool = pwq->pool;
struct work_struct *work, *n;
+ bool first = true;
__set_current_state(TASK_RUNNING);
list_del_init(&pwq->mayday_node);
* process'em.
*/
WARN_ON_ONCE(!list_empty(scheduled));
- list_for_each_entry_safe(work, n, &pool->worklist, entry)
- if (get_work_pwq(work) == pwq)
+ list_for_each_entry_safe(work, n, &pool->worklist, entry) {
+ if (get_work_pwq(work) == pwq) {
+ if (first)
+ pool->watchdog_ts = jiffies;
move_linked_works(work, scheduled, &n);
+ }
+ first = false;
+ }
if (!list_empty(scheduled)) {
process_scheduled_works(rescuer);
pool->cpu = -1;
pool->node = NUMA_NO_NODE;
pool->flags |= POOL_DISASSOCIATED;
+ pool->watchdog_ts = jiffies;
INIT_LIST_HEAD(&pool->worklist);
INIT_LIST_HEAD(&pool->idle_list);
hash_init(pool->busy_hash);
pr_info("pool %d:", pool->id);
pr_cont_pool_info(pool);
- pr_cont(" workers=%d", pool->nr_workers);
+ pr_cont(" hung=%us workers=%d",
+ jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000,
+ pool->nr_workers);
if (pool->manager)
pr_cont(" manager: %d",
task_pid_nr(pool->manager->task));
static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { }
#endif /* CONFIG_SYSFS */
+/*
+ * Workqueue watchdog.
+ *
+ * Stall may be caused by various bugs - missing WQ_MEM_RECLAIM, illegal
+ * flush dependency, a concurrency managed work item which stays RUNNING
+ * indefinitely. Workqueue stalls can be very difficult to debug as the
+ * usual warning mechanisms don't trigger and internal workqueue state is
+ * largely opaque.
+ *
+ * Workqueue watchdog monitors all worker pools periodically and dumps
+ * state if some pools failed to make forward progress for a while where
+ * forward progress is defined as the first item on ->worklist changing.
+ *
+ * This mechanism is controlled through the kernel parameter
+ * "workqueue.watchdog_thresh" which can be updated at runtime through the
+ * corresponding sysfs parameter file.
+ */
+#ifdef CONFIG_WQ_WATCHDOG
+
+static void wq_watchdog_timer_fn(unsigned long data);
+
+static unsigned long wq_watchdog_thresh = 30;
+static struct timer_list wq_watchdog_timer =
+ TIMER_DEFERRED_INITIALIZER(wq_watchdog_timer_fn, 0, 0);
+
+static unsigned long wq_watchdog_touched = INITIAL_JIFFIES;
+static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES;
+
+static void wq_watchdog_reset_touched(void)
+{
+ int cpu;
+
+ wq_watchdog_touched = jiffies;
+ for_each_possible_cpu(cpu)
+ per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies;
+}
+
+static void wq_watchdog_timer_fn(unsigned long data)
+{
+ unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ;
+ bool lockup_detected = false;
+ struct worker_pool *pool;
+ int pi;
+
+ if (!thresh)
+ return;
+
+ rcu_read_lock();
+
+ for_each_pool(pool, pi) {
+ unsigned long pool_ts, touched, ts;
+
+ if (list_empty(&pool->worklist))
+ continue;
+
+ /* get the latest of pool and touched timestamps */
+ pool_ts = READ_ONCE(pool->watchdog_ts);
+ touched = READ_ONCE(wq_watchdog_touched);
+
+ if (time_after(pool_ts, touched))
+ ts = pool_ts;
+ else
+ ts = touched;
+
+ if (pool->cpu >= 0) {
+ unsigned long cpu_touched =
+ READ_ONCE(per_cpu(wq_watchdog_touched_cpu,
+ pool->cpu));
+ if (time_after(cpu_touched, ts))
+ ts = cpu_touched;
+ }
+
+ /* did we stall? */
+ if (time_after(jiffies, ts + thresh)) {
+ lockup_detected = true;
+ pr_emerg("BUG: workqueue lockup - pool");
+ pr_cont_pool_info(pool);
+ pr_cont(" stuck for %us!\n",
+ jiffies_to_msecs(jiffies - pool_ts) / 1000);
+ }
+ }
+
+ rcu_read_unlock();
+
+ if (lockup_detected)
+ show_workqueue_state();
+
+ wq_watchdog_reset_touched();
+ mod_timer(&wq_watchdog_timer, jiffies + thresh);
+}
+
+void wq_watchdog_touch(int cpu)
+{
+ if (cpu >= 0)
+ per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies;
+ else
+ wq_watchdog_touched = jiffies;
+}
+
+static void wq_watchdog_set_thresh(unsigned long thresh)
+{
+ wq_watchdog_thresh = 0;
+ del_timer_sync(&wq_watchdog_timer);
+
+ if (thresh) {
+ wq_watchdog_thresh = thresh;
+ wq_watchdog_reset_touched();
+ mod_timer(&wq_watchdog_timer, jiffies + thresh * HZ);
+ }
+}
+
+static int wq_watchdog_param_set_thresh(const char *val,
+ const struct kernel_param *kp)
+{
+ unsigned long thresh;
+ int ret;
+
+ ret = kstrtoul(val, 0, &thresh);
+ if (ret)
+ return ret;
+
+ if (system_wq)
+ wq_watchdog_set_thresh(thresh);
+ else
+ wq_watchdog_thresh = thresh;
+
+ return 0;
+}
+
+static const struct kernel_param_ops wq_watchdog_thresh_ops = {
+ .set = wq_watchdog_param_set_thresh,
+ .get = param_get_ulong,
+};
+
+module_param_cb(watchdog_thresh, &wq_watchdog_thresh_ops, &wq_watchdog_thresh,
+ 0644);
+
+static void wq_watchdog_init(void)
+{
+ wq_watchdog_set_thresh(wq_watchdog_thresh);
+}
+
+#else /* CONFIG_WQ_WATCHDOG */
+
+static inline void wq_watchdog_init(void) { }
+
+#endif /* CONFIG_WQ_WATCHDOG */
+
static void __init wq_numa_init(void)
{
cpumask_var_t *tbl;
!system_unbound_wq || !system_freezable_wq ||
!system_power_efficient_wq ||
!system_freezable_power_efficient_wq);
+
+ wq_watchdog_init();
+
return 0;
}
early_initcall(init_workqueues);
projects / cascardo / linux.git / commitdiff