io_wq_put_and_exit() is called from do_exit(), but all FIXED_FILE requests in io_wq aren't canceled in io_uring_cancel_generic() called from do_exit(). Meantime io_wq IO code path may share resource with normal iopoll code path. So if any HIPRI request is submittd via io_wq, this request may not get resouce for moving on, given iopoll isn't possible in io_wq_put_and_exit(). The issue can be triggered when terminating 't/io_uring -n4 /dev/nullb0' with default null_blk parameters. Fix it by always cancelling all requests in io_wq by adding helper of io_uring_cancel_wq(), and this way is reasonable because io_wq destroying follows canceling requests immediately. Closes: https://lore.kernel.org/linux-block/3893581.1691785261@xxxxxxxxxxxxxxxxxxxxxx/ Reported-by: David Howells <dhowells@xxxxxxxxxx> Cc: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>, Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> --- V2: - avoid to mess up io_uring_cancel_generic() by adding one new helper for canceling io_wq requests io_uring/io_uring.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index f4591b912ea8..7b3518f96c3b 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -3298,6 +3298,37 @@ static s64 tctx_inflight(struct io_uring_task *tctx, bool tracked) return percpu_counter_sum(&tctx->inflight); } +static void io_uring_cancel_wq(struct io_uring_task *tctx) +{ + int ret; + + if (!tctx->io_wq) + return; + + /* + * FIXED_FILE request isn't tracked in do_exit(), and these + * requests may be submitted to our io_wq as iopoll, so have to + * cancel them before destroying io_wq for avoiding IO hang + */ + do { + struct io_tctx_node *node; + unsigned long index; + + ret = 0; + xa_for_each(&tctx->xa, index, node) { + struct io_ring_ctx *ctx = node->ctx; + struct io_task_cancel cancel = { .task = current, .all = true, }; + enum io_wq_cancel cret; + + io_iopoll_try_reap_events(ctx); + cret = io_wq_cancel_cb(tctx->io_wq, io_cancel_task_cb, + &cancel, true); + ret |= (cret != IO_WQ_CANCEL_NOTFOUND); + cond_resched(); + } + } while (ret); +} + /* * Find any io_uring ctx that this task has registered or done IO on, and cancel * requests. @sqd should be not-null IFF it's an SQPOLL thread cancellation. @@ -3369,6 +3400,7 @@ __cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd) finish_wait(&tctx->wait, &wait); } while (1); + io_uring_cancel_wq(tctx); io_uring_clean_tctx(tctx); if (cancel_all) { /* -- 2.41.0
