return atomic_read(&compound_head(page)->_count);
}
+#ifdef CONFIG_HUGETLB_PAGE
+extern int PageHeadHuge(struct page *page_head);
+#else /* CONFIG_HUGETLB_PAGE */
+static inline int PageHeadHuge(struct page *page_head)
+{
+ return 0;
+}
+#endif /* CONFIG_HUGETLB_PAGE */
+
+static inline bool __compound_tail_refcounted(struct page *page)
+{
+ return !PageSlab(page) && !PageHeadHuge(page);
+}
+
+/*
+ * This takes a head page as parameter and tells if the
+ * tail page reference counting can be skipped.
+ *
+ * For this to be safe, PageSlab and PageHeadHuge must remain true on
+ * any given page where they return true here, until all tail pins
+ * have been released.
+ */
+static inline bool compound_tail_refcounted(struct page *page)
+{
+ VM_BUG_ON(!PageHead(page));
+ return __compound_tail_refcounted(page);
+}
+
static inline void get_huge_page_tail(struct page *page)
{
/*
- * __split_huge_page_refcount() cannot run
- * from under us.
+ * __split_huge_page_refcount() cannot run from under us.
*/
+ VM_BUG_ON(!PageTail(page));
VM_BUG_ON(page_mapcount(page) < 0);
VM_BUG_ON(atomic_read(&page->_count) != 0);
- atomic_inc(&page->_mapcount);
+ if (compound_tail_refcounted(page->first_page))
+ atomic_inc(&page->_mapcount);
}
extern bool __get_page_tail(struct page *page);
#endif
#if defined(WANT_PAGE_VIRTUAL)
-#define page_address(page) ((page)->virtual)
-#define set_page_address(page, address) \
- do { \
- (page)->virtual = (address); \
- } while(0)
+static inline void *page_address(const struct page *page)
+{
+ return page->virtual;
+}
+static inline void set_page_address(struct page *page, void *address)
+{
+ page->virtual = address;
+}
#define page_address_init() do { } while(0)
#endif