On 5/21/21 9:45 AM, Zhang, Qiang wrote:
[...]
> It looks like
> thread iou-wrk-28796 in io-wq(A) access wqe in the wait queue(data->hash->wait), but this wqe has been free due to the destruction of another io-wq(B).
>
> Should we after wait for all iou-wrk thread exit in the io-wq， remove wqe from the waiting queue (data->hash->wait). prevent some one wqe belonging to this io-wq , may be still existing in the (data->hash->wait)queue before releasing.
The guess looks reasonable, it's likely a problem.
Not sure about the diff, it seems racy but I need to
take a closer look to say for sure
> look forward to your opinion.
>
> --- a/fs/io-wq.c
> +++ b/fs/io-wq.c
> @@ -1003,13 +1003,17 @@ static void io_wq_exit_workers(struct io_wq *wq)
> struct io_wqe *wqe = wq->wqes[node];
>
> io_wq_for_each_worker(wqe, io_wq_worker_wake, NULL);
> - spin_lock_irq(&wq->hash->wait.lock);
> - list_del_init(&wq->wqes[node]->wait.entry);
> - spin_unlock_irq(&wq->hash->wait.lock);
> }
> rcu_read_unlock();
> io_worker_ref_put(wq);
> wait_for_completion(&wq->worker_done);
> + for_each_node(node) {
> + struct io_wqe *wqe = wq->wqes[node];
> +
> + spin_lock_irq(&wq->hash->wait.lock);
> + list_del_init(&wq->wqes[node]->wait.entry);
> + spin_unlock_irq(&wq->hash->wait.lock);
> + }
> put_task_struct(wq->task);
> wq->task = NULL;
> }
--
Pavel Begunkov
