io_uring: kill cached requests from exiting task closing the ring

Be nice and prune these upfront, in case the ring is being shared and
one of the tasks is going away. This is a bit more important now that
we account the allocations.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -9232,8 +9232,10 @@ static int io_uring_flush(struct file *file, void *data)
 	struct io_uring_task *tctx = current->io_uring;
 	struct io_ring_ctx *ctx = file->private_data;
 
-	if (fatal_signal_pending(current) || (current->flags & PF_EXITING))
+	if (fatal_signal_pending(current) || (current->flags & PF_EXITING)) {
 		io_uring_cancel_task_requests(ctx, NULL);
+		io_req_caches_free(ctx, current);
+	}
 
 	if (!tctx)
 		return 0;