*
* Also, many kernel routines increase the page count before a critical
* routine so they can be sure the page doesn't go away from under them.
- *
- * Since 2.6.6 (approx), a free page has ->_count = -1. This is so that we
- * can use atomic_add_negative(-1, page->_count) to detect when the page
- * becomes free and so that we can also use atomic_inc_and_test to atomically
- * detect when we just tried to grab a ref on a page which some other CPU has
- * already deemed to be freeable.
- *
- * NO code should make assumptions about this internal detail! Use the provided
- * macros which retain the old rules: page_count(page) == 0 is a free page.
*/
/*
* Drop a ref, return true if the logical refcount fell to zero (the page has
* no users)
*/
-#define put_page_testzero(p) \
- ({ \
- BUG_ON(atomic_read(&(p)->_count) == -1);\
- atomic_add_negative(-1, &(p)->_count); \
- })
+static inline int put_page_testzero(struct page *page)
+{
+ BUG_ON(atomic_read(&page->_count) == 0);
+ return atomic_dec_and_test(&page->_count);
+}
/*
- * Grab a ref, return true if the page previously had a logical refcount of
- * zero. ie: returns true if we just grabbed an already-deemed-to-be-free page
+ * Try to grab a ref unless the page has a refcount of zero, return false if
+ * that is the case.
*/
-#define get_page_testone(p) atomic_inc_and_test(&(p)->_count)
+static inline int get_page_unless_zero(struct page *page)
+{
+ return atomic_inc_not_zero(&page->_count);
+}
-#define set_page_count(p,v) atomic_set(&(p)->_count, (v) - 1)
+#define set_page_count(p,v) atomic_set(&(p)->_count, (v))
#define __put_page(p) atomic_dec(&(p)->_count)
extern void FASTCALL(__page_cache_release(struct page *));
{
if (PageCompound(page))
page = (struct page *)page_private(page);
- return atomic_read(&page->_count) + 1;
+ return atomic_read(&page->_count);
}
static inline void get_page(struct page *page)
void put_page(struct page *page);
+#ifdef CONFIG_MMU
+void split_page(struct page *page, unsigned int order);
+#else
+static inline void split_page(struct page *page, unsigned int order) {}
+#endif
+
/*
* Multiple processes may "see" the same page. E.g. for untouched
* mappings of /dev/null, all processes see the same page full of
int drop_caches_sysctl_handler(struct ctl_table *, int, struct file *,
void __user *, size_t *, loff_t *);
-int shrink_slab(unsigned long scanned, gfp_t gfp_mask,
+unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
unsigned long lru_pages);
void drop_pagecache(void);
void drop_slab(void);
+#ifndef CONFIG_MMU
+#define randomize_va_space 0
+#else
extern int randomize_va_space;
+#endif
#endif /* __KERNEL__ */
#endif /* _LINUX_MM_H */