io_uring: don't attempt IO reissue from the ring exit path

If we're exiting the ring, just let the IO fail with -EAGAIN as nobody
will care anyway. It's not the right context to reissue from.

Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -2839,6 +2839,13 @@ static bool io_rw_reissue(struct io_kiocb *req)
 		return false;
 	if ((req->flags & REQ_F_NOWAIT) || io_wq_current_is_worker())
 		return false;
+	/*
+	 * If ref is dying, we might be running poll reap from the exit work.
+	 * Don't attempt to reissue from that path, just let it fail with
+	 * -EAGAIN.
+	 */
+	if (percpu_ref_is_dying(&req->ctx->refs))
+		return false;
 
 	lockdep_assert_held(&req->ctx->uring_lock);