broken daemonize (COW credentials?)

[Jiri Slaby <jirislaby@gmail.com>]

Hi,

I'm observing daemonize crashes with this code:
static struct pid *pid;
static DECLARE_COMPLETION(comp);

static int bubak(void *data)
{
        daemonize("bubak");
        while (!signal_pending(current))
                msleep_interruptible(5000);
        complete_and_exit(&comp, 0);
        return 0;
}

static int init1(void) <-- module_init function
{
        int ret;

        ret = kernel_thread(bubak, NULL, 0);
        if (ret < 0)
                return ret;
        pid = find_get_pid(ret);
	return 0;
}
----------------------- cut here -------------------

This is due to:
daemonize
 -> exit_mm
   -> tsk->mm = NULL; (i.e. current->mm)
 -> reparent_to_kthreadd
   -> commit_creds
     -> set_dumpable(task->mm, suid_dumpable); (i.e. current->mm)

The culprit is probably COW credentials. David?