/*
* PageBuddy() indicate that the page is free and in the buddy system
* (see mm/page_alloc.c).
+ *
+ * PAGE_BUDDY_MAPCOUNT_VALUE must be <= -2 but better not too close to
+ * -2 so that an underflow of the page_mapcount() won't be mistaken
+ * for a genuine PAGE_BUDDY_MAPCOUNT_VALUE. -128 can be created very
+ * efficiently by most CPU architectures.
*/
+#define PAGE_BUDDY_MAPCOUNT_VALUE (-128)
+
static inline int PageBuddy(struct page *page)
{
- return atomic_read(&page->_mapcount) == -2;
+ return atomic_read(&page->_mapcount) == PAGE_BUDDY_MAPCOUNT_VALUE;
}
static inline void __SetPageBuddy(struct page *page)
{
VM_BUG_ON(atomic_read(&page->_mapcount) != -1);
- atomic_set(&page->_mapcount, -2);
+ atomic_set(&page->_mapcount, PAGE_BUDDY_MAPCOUNT_VALUE);
}
static inline void __ClearPageBuddy(struct page *page)
extern void shake_page(struct page *p, int access);
extern atomic_long_t mce_bad_pages;
extern int soft_offline_page(struct page *page, int flags);
-#ifdef CONFIG_MEMORY_FAILURE
-int is_hwpoison_address(unsigned long addr);
-#else
-static inline int is_hwpoison_address(unsigned long addr)
-{
- return 0;
-}
-#endif
extern void dump_page(struct page *page);