static void fill_random_ptr_key(struct random_ready_callback *unused)
{
	get_random_bytes(&ptr_key, sizeof(ptr_key));
	/*
	 * have_filled_random_ptr_key==true is dependent on get_random_bytes().
	 * ptr_to_id() needs to see have_filled_random_ptr_key==true
	 * after get_random_bytes() returns.
	 */
	smp_mb();
	WRITE_ONCE(have_filled_random_ptr_key, true);
}
static void fill_random_ptr_key(struct random_ready_callback *unused)
{
	get_random_bytes(&ptr_key, sizeof(ptr_key));
	 
	smp_mb();
	WRITE_ONCE(have_filled_random_ptr_key, true);
}