On 6/30/20 8:36 AM, Pavel Begunkov wrote: > On 30/06/2020 17:04, Jens Axboe wrote: >> On 6/30/20 6:20 AM, Pavel Begunkov wrote: >>> Don't call io_commit_cqring() without holding the completion spinlock >>> in io_iopoll_complete(), it can race, e.g. with async request failing. >> >> Can you be more specific? > > io_iopoll_complete() > -> io_req_free_batch() > -> io_queue_next() > -> io_req_task_queue() > -> task_work_add() > > if this task_work_add() fails, it will be redirected to io-wq manager task > to do io_req_task_cancel() -> commit_cqring(). > > > And probably something similar will happen if a request currently in io-wq > is retried with > io_rw_should_retry() -> io_async_buf_func() -> task_work_add() For the IOPOLL setup, it should be protected by the ring mutex. Adding the irq disable + lock for polling would be a nasty performance hit. -- Jens Axboe
