From 8a80eddcec0f7b6e1bc7ca7945cdeae9d35f31b4 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 18 May 2020 11:04:17 -0600 Subject: [PATCH] io_uring: cancel work if task_work_add() fails We currently move it to the io_wqe_manager for execution, but we cannot safely do so as we may lack some of the state to execute it out of context. As we cancel work anyway when the ring/task exits, just mark this request as canceled and io_async_task_func() will do the right thing. Fixes: 0be7ca8b9b47 ("io_uring: use io-wq manager as backup task if task is exiting") Signed-off-by: Jens Axboe --- fs/io_uring.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index ecfd7f054ef68..29aa53000def7 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -4135,12 +4135,14 @@ static int __io_async_wake(struct io_kiocb *req, struct io_poll_iocb *poll, req->result = mask; init_task_work(&req->task_work, func); /* - * If this fails, then the task is exiting. Punt to one of the io-wq - * threads to ensure the work gets run, we can't always rely on exit - * cancelation taking care of this. + * If this fails, then the task is exiting. When a task exits, the + * work gets canceled, so just cancel this request as well instead + * of executing it. We can't safely execute it anyway, as we may not + * have the needed state needed for it anyway. */ ret = task_work_add(tsk, &req->task_work, true); if (unlikely(ret)) { + WRITE_ONCE(poll->canceled, true); tsk = io_wq_get_task(req->ctx->io_wq); task_work_add(tsk, &req->task_work, true); } -- 2.39.5