diff options
| -rw-r--r-- | MAINTAINERS | 1 | ||||
| -rw-r--r-- | include/linux/workqueue.h | 1 | ||||
| -rw-r--r-- | kernel/power/process.c | 2 | ||||
| -rw-r--r-- | kernel/workqueue.c | 134 |
4 files changed, 124 insertions, 14 deletions
diff --git a/MAINTAINERS b/MAINTAINERS index 4e9370793300..e2a91d048365 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -22743,6 +22743,7 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git F: Documentation/core-api/workqueue.rst F: include/linux/workqueue.h F: kernel/workqueue.c +F: kernel/workqueue_internal.h WWAN DRIVERS M: Loic Poulain <loic.poulain@linaro.org> diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index ac551b8ee7d9..3992c994787f 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -472,6 +472,7 @@ extern unsigned int work_busy(struct work_struct *work); extern __printf(1, 2) void set_worker_desc(const char *fmt, ...); extern void print_worker_info(const char *log_lvl, struct task_struct *task); extern void show_all_workqueues(void); +extern void show_freezable_workqueues(void); extern void show_one_workqueue(struct workqueue_struct *wq); extern void wq_worker_comm(char *buf, size_t size, struct task_struct *task); diff --git a/kernel/power/process.c b/kernel/power/process.c index 6c1c7e566d35..cae81a87cc91 100644 --- a/kernel/power/process.c +++ b/kernel/power/process.c @@ -93,7 +93,7 @@ static int try_to_freeze_tasks(bool user_only) todo - wq_busy, wq_busy); if (wq_busy) - show_all_workqueues(); + show_freezable_workqueues(); if (!wakeup || pm_debug_messages_on) { read_lock(&tasklist_lock); diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 209917792fa4..4666a1a92a31 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -49,6 +49,7 @@ #include <linux/moduleparam.h> #include <linux/uaccess.h> #include <linux/sched/isolation.h> +#include <linux/sched/debug.h> #include <linux/nmi.h> #include <linux/kvm_para.h> @@ -141,6 +142,8 @@ enum { * WR: wq->mutex protected for writes. RCU protected for reads. * * MD: wq_mayday_lock protected. + * + * WD: Used internally by the watchdog. */ /* struct worker is defined in workqueue_internal.h */ @@ -153,6 +156,7 @@ struct worker_pool { unsigned int flags; /* X: flags */ unsigned long watchdog_ts; /* L: watchdog timestamp */ + bool cpu_stall; /* WD: stalled cpu bound pool */ /* * The counter is incremented in a process context on the associated CPU @@ -1392,15 +1396,13 @@ static bool is_chained_work(struct workqueue_struct *wq) */ static int wq_select_unbound_cpu(int cpu) { - static bool printed_dbg_warning; int new_cpu; if (likely(!wq_debug_force_rr_cpu)) { if (cpumask_test_cpu(cpu, wq_unbound_cpumask)) return cpu; - } else if (!printed_dbg_warning) { - pr_warn("workqueue: round-robin CPU selection forced, expect performance impact\n"); - printed_dbg_warning = true; + } else { + pr_warn_once("workqueue: round-robin CPU selection forced, expect performance impact\n"); } if (cpumask_empty(wq_unbound_cpumask)) @@ -1938,12 +1940,17 @@ static struct worker *create_worker(struct worker_pool *pool) /* ID is needed to determine kthread name */ id = ida_alloc(&pool->worker_ida, GFP_KERNEL); - if (id < 0) + if (id < 0) { + pr_err_once("workqueue: Failed to allocate a worker ID: %pe\n", + ERR_PTR(id)); return NULL; + } worker = alloc_worker(pool->node); - if (!worker) + if (!worker) { + pr_err_once("workqueue: Failed to allocate a worker\n"); goto fail; + } worker->id = id; @@ -1955,8 +1962,16 @@ static struct worker *create_worker(struct worker_pool *pool) worker->task = kthread_create_on_node(worker_thread, worker, pool->node, "kworker/%s", id_buf); - if (IS_ERR(worker->task)) + if (IS_ERR(worker->task)) { + if (PTR_ERR(worker->task) == -EINTR) { + pr_err("workqueue: Interrupted when creating a worker thread \"kworker/%s\"\n", + id_buf); + } else { + pr_err_once("workqueue: Failed to create a worker thread: %pe", + worker->task); + } goto fail; + } set_user_nice(worker->task, pool->attrs->nice); kthread_bind_mask(worker->task, pool->attrs->cpumask); @@ -4380,13 +4395,18 @@ static int init_rescuer(struct workqueue_struct *wq) return 0; rescuer = alloc_worker(NUMA_NO_NODE); - if (!rescuer) + if (!rescuer) { + pr_err("workqueue: Failed to allocate a rescuer for wq \"%s\"\n", + wq->name); return -ENOMEM; + } rescuer->rescue_wq = wq; rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", wq->name); if (IS_ERR(rescuer->task)) { ret = PTR_ERR(rescuer->task); + pr_err("workqueue: Failed to create a rescuer kthread for wq \"%s\": %pe", + wq->name, ERR_PTR(ret)); kfree(rescuer); return ret; } @@ -5002,10 +5022,16 @@ static void show_one_worker_pool(struct worker_pool *pool) struct worker *worker; bool first = true; unsigned long flags; + unsigned long hung = 0; raw_spin_lock_irqsave(&pool->lock, flags); if (pool->nr_workers == pool->nr_idle) goto next_pool; + + /* How long the first pending work is waiting for a worker. */ + if (!list_empty(&pool->worklist)) + hung = jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000; + /* * Defer printing to avoid deadlocks in console drivers that * queue work while holding locks also taken in their write @@ -5014,9 +5040,7 @@ static void show_one_worker_pool(struct worker_pool *pool) printk_deferred_enter(); pr_info("pool %d:", pool->id); pr_cont_pool_info(pool); - pr_cont(" hung=%us workers=%d", - jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000, - pool->nr_workers); + pr_cont(" hung=%lus workers=%d", hung, pool->nr_workers); if (pool->manager) pr_cont(" manager: %d", task_pid_nr(pool->manager->task)); @@ -5041,8 +5065,7 @@ next_pool: /** * show_all_workqueues - dump workqueue state * - * Called from a sysrq handler or try_to_freeze_tasks() and prints out - * all busy workqueues and pools. + * Called from a sysrq handler and prints out all busy workqueues and pools. */ void show_all_workqueues(void) { @@ -5063,6 +5086,29 @@ void show_all_workqueues(void) rcu_read_unlock(); } +/** + * show_freezable_workqueues - dump freezable workqueue state + * + * Called from try_to_freeze_tasks() and prints out all freezable workqueues + * still busy. + */ +void show_freezable_workqueues(void) +{ + struct workqueue_struct *wq; + + rcu_read_lock(); + + pr_info("Showing freezable workqueues that are still busy:\n"); + + list_for_each_entry_rcu(wq, &workqueues, list) { + if (!(wq->flags & WQ_FREEZABLE)) + continue; + show_one_workqueue(wq); + } + + rcu_read_unlock(); +} + /* used to show worker information through /proc/PID/{comm,stat,status} */ void wq_worker_comm(char *buf, size_t size, struct task_struct *task) { @@ -5962,6 +6008,57 @@ static struct timer_list wq_watchdog_timer; static unsigned long wq_watchdog_touched = INITIAL_JIFFIES; static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES; +/* + * Show workers that might prevent the processing of pending work items. + * The only candidates are CPU-bound workers in the running state. + * Pending work items should be handled by another idle worker + * in all other situations. + */ +static void show_cpu_pool_hog(struct worker_pool *pool) +{ + struct worker *worker; + unsigned long flags; + int bkt; + + raw_spin_lock_irqsave(&pool->lock, flags); + + hash_for_each(pool->busy_hash, bkt, worker, hentry) { + if (task_is_running(worker->task)) { + /* + * Defer printing to avoid deadlocks in console + * drivers that queue work while holding locks + * also taken in their write paths. + */ + printk_deferred_enter(); + + pr_info("pool %d:\n", pool->id); + sched_show_task(worker->task); + + printk_deferred_exit(); + } + } + + raw_spin_unlock_irqrestore(&pool->lock, flags); +} + +static void show_cpu_pools_hogs(void) +{ + struct worker_pool *pool; + int pi; + + pr_info("Showing backtraces of running workers in stalled CPU-bound worker pools:\n"); + + rcu_read_lock(); + + for_each_pool(pool, pi) { + if (pool->cpu_stall) + show_cpu_pool_hog(pool); + + } + + rcu_read_unlock(); +} + static void wq_watchdog_reset_touched(void) { int cpu; @@ -5975,6 +6072,7 @@ static void wq_watchdog_timer_fn(struct timer_list *unused) { unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ; bool lockup_detected = false; + bool cpu_pool_stall = false; unsigned long now = jiffies; struct worker_pool *pool; int pi; @@ -5987,6 +6085,7 @@ static void wq_watchdog_timer_fn(struct timer_list *unused) for_each_pool(pool, pi) { unsigned long pool_ts, touched, ts; + pool->cpu_stall = false; if (list_empty(&pool->worklist)) continue; @@ -6011,11 +6110,17 @@ static void wq_watchdog_timer_fn(struct timer_list *unused) /* did we stall? */ if (time_after(now, ts + thresh)) { lockup_detected = true; + if (pool->cpu >= 0) { + pool->cpu_stall = true; + cpu_pool_stall = true; + } pr_emerg("BUG: workqueue lockup - pool"); pr_cont_pool_info(pool); pr_cont(" stuck for %us!\n", jiffies_to_msecs(now - pool_ts) / 1000); } + + } rcu_read_unlock(); @@ -6023,6 +6128,9 @@ static void wq_watchdog_timer_fn(struct timer_list *unused) if (lockup_detected) show_all_workqueues(); + if (cpu_pool_stall) + show_cpu_pools_hogs(); + wq_watchdog_reset_touched(); mod_timer(&wq_watchdog_timer, jiffies + thresh); } |