From: Petr Mladek pmladek@suse.com
[ Upstream commit 335a42ebb0ca8ee9997a1731aaaae6dcd704c113 ]
The workqueue watchdog prints a warning when there is no progress in a worker pool. Where the progress means that the pool started processing a pending work item.
Note that it is perfectly fine to process work items much longer. The progress should be guaranteed by waking up or creating idle workers.
show_one_worker_pool() prints state of non-idle worker pool. It shows a delay since the last pool->watchdog_ts.
The timestamp is updated when a first pending work is queued in __queue_work(). Also it is updated when a work is dequeued for processing in worker_thread() and rescuer_thread().
The delay is misleading when there is no pending work item. In this case it shows how long the last work item is being proceed. Show zero instead. There is no stall if there is no pending work.
Fixes: 82607adcf9cdf40fb7b ("workqueue: implement lockup detector") Signed-off-by: Petr Mladek pmladek@suse.com Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/workqueue.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 7f57fed719957..b9041ab881bc8 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -4816,16 +4816,19 @@ void show_workqueue_state(void) for_each_pool(pool, pi) { struct worker *worker; bool first = true; + 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; + 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));