mm/thp: use head for head page in lru_add_page_tail()

	}

}

static void lru_add_page_tail(struct page *page, struct page *page_tail,

static void lru_add_page_tail(struct page *head, struct page *tail,

		struct lruvec *lruvec, struct list_head *list)

{

	VM_BUG_ON_PAGE(!PageHead(page), page);

	VM_BUG_ON_PAGE(PageCompound(page_tail), page);

	VM_BUG_ON_PAGE(PageLRU(page_tail), page);

	VM_BUG_ON_PAGE(!PageHead(head), head);

	VM_BUG_ON_PAGE(PageCompound(tail), head);

	VM_BUG_ON_PAGE(PageLRU(tail), head);

	lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);

	if (!list)

		SetPageLRU(page_tail);

		SetPageLRU(tail);

	if (likely(PageLRU(page)))

		list_add_tail(&page_tail->lru, &page->lru);

	if (likely(PageLRU(head)))

		list_add_tail(&tail->lru, &head->lru);

	else if (list) {

		/* page reclaim is reclaiming a huge page */

		get_page(page_tail);

		list_add_tail(&page_tail->lru, list);

		get_page(tail);

		list_add_tail(&tail->lru, list);

	} else {

		/*

		 * Head page has not yet been counted, as an hpage,

		 * so we must account for each subpage individually.

		 *

		 * Put page_tail on the list at the correct position

		 * Put tail on the list at the correct position

		 * so they all end up in order.

		 */

		add_page_to_lru_list_tail(page_tail, lruvec,

					  page_lru(page_tail));

		add_page_to_lru_list_tail(tail, lruvec, page_lru(tail));

	}

}