io_uring: complete request via task work in case of DEFER_TASKRUN

commit 860e1c7f8b0b43fbf91b4d689adfaa13adb89452 upstream.

So far io_req_complete_post() only covers DEFER_TASKRUN by completing
request via task work when the request is completed from IOWQ.

However, uring command could be completed from any context, and if io
uring is setup with DEFER_TASKRUN, the command is required to be
completed from current context, otherwise wait on IORING_ENTER_GETEVENTS
can't be wakeup, and may hang forever.

The issue can be observed on removing ublk device, but turns out it is
one generic issue for uring command & DEFER_TASKRUN, so solve it in
io_uring core code.

Fixes: e6aeb2721d3b ("io_uring: complete all requests in task context")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/linux-block/b3fc9991-4c53-9218-a8cc-5b4dd3952108@kernel.dk/
Reported-by: Jens Axboe <axboe@kernel.dk>
Cc: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index add5cff7952c570955759d70c31090934f5ad376..14d4fa64684174062c0c604ac5c302ab09b7e838 100644 (file)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -962,7 +962,7 @@ static void __io_req_complete_post(struct io_kiocb *req)
 
 void io_req_complete_post(struct io_kiocb *req, unsigned issue_flags)
 {
-       if (req->ctx->task_complete && (issue_flags & IO_URING_F_IOWQ)) {
+       if (req->ctx->task_complete && req->ctx->submitter_task != current) {
                req->io_task_work.func = io_req_task_complete;
                io_req_task_work_add(req);
        } else if (!(issue_flags & IO_URING_F_UNLOCKED) ||