*
* 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.
*/
/*
*/
static inline int put_page_testzero(struct page *page)
{
- BUG_ON(atomic_read(&page->_count) == -1);
- return atomic_add_negative(-1, &page->_count);
+ BUG_ON(atomic_read(&page->_count) == 0);
+ return atomic_dec_and_test(&page->_count);
}
/*
*/
static inline int get_page_unless_zero(struct page *page)
{
- return atomic_add_unless(&page->_count, 1, -1);
+ return atomic_inc_not_zero(&page->_count);
}
-#define set_page_count(p,v) atomic_set(&(p)->_count, (v) - 1)
-#define __put_page(p) atomic_dec(&(p)->_count)
-
extern void FASTCALL(__page_cache_release(struct page *));
static inline int page_count(struct page *page)
{
- if (PageCompound(page))
+ if (unlikely(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)
atomic_inc(&page->_count);
}
+/*
+ * Setup the page count before being freed into the page allocator for
+ * the first time (boot or memory hotplug)
+ */
+static inline void init_page_count(struct page *page)
+{
+ atomic_set(&page->_count, 1);
+}
+
void put_page(struct page *page);
+void split_page(struct page *page, unsigned int order);
+
/*
* 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);