int pin_user_pages_fast(unsigned long start, int nr_pages,
			unsigned int gup_flags, struct page **pages)
{
	/* FOLL_GET and FOLL_PIN are mutually exclusive. */
	if (WARN_ON_ONCE(gup_flags & FOLL_GET))
		return -EINVAL;

	gup_flags |= FOLL_PIN;
	return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages);
}
int pin_user_pages_fast(unsigned long start, int nr_pages,
			unsigned int gup_flags, struct page **pages)
{
	 
	if (WARN_ON_ONCE(gup_flags & FOLL_GET))
		return -EINVAL;

	gup_flags |= FOLL_PIN;
	return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages);
}