关于内核线程和rmmod模块的问题

xiaocainiao2011

int init_module()
{
    netlink_exam_sock = netlink_kernel_create(NETLINK_GENERIC, 0,recv_handler,NULL);
    if (!netlink_exam_sock)
    {
        printk("Fail to create netlink socket.\n");
        return 1;
    }

    kernel_thread(process_message_thread, NULL, CLONE_KERNEL);
    return 0;
}
void cleanup_module()
{
    exit_flag = 1;
    wake_up(netlink_exam_sock->sk_sleep);
    wait_for_completion(&exit_completion);
    sock_release(netlink_exam_sock->sk_socket);
}

insmod 模块后能运行，但我想卸除模块的时候，总是显示 Device or resource busy
请问我怎样才能撤销内核线程？哪位高人指点一下，谢谢了

renminbi

kthread_stop().