include/linux/page_ext.h

   1 #ifndef __LINUX_PAGE_EXT_H
   2 #define __LINUX_PAGE_EXT_H
   3
   4 #include <linux/types.h>
   5 #include <linux/stacktrace.h>
   6 #include <linux/stackdepot.h>
   7
   8 struct pglist_data;
   9 struct page_ext_operations {
  10         size_t offset;
  11         size_t size;
  12         bool (*need)(void);
  13         void (*init)(void);
  14 };
  15
  16 #ifdef CONFIG_PAGE_EXTENSION
  17
  18 /*
  19  * page_ext->flags bits:
  20  *
  21  * PAGE_EXT_DEBUG_POISON is set for poisoned pages. This is used to
  22  * implement generic debug pagealloc feature. The pages are filled with
  23  * poison patterns and set this flag after free_pages(). The poisoned
  24  * pages are verified whether the patterns are not corrupted and clear
  25  * the flag before alloc_pages().
  26  */
  27
  28 enum page_ext_flags {
  29         PAGE_EXT_DEBUG_POISON,          /* Page is poisoned */
  30         PAGE_EXT_DEBUG_GUARD,
  31         PAGE_EXT_OWNER,
  32 #if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
  33         PAGE_EXT_YOUNG,
  34         PAGE_EXT_IDLE,
  35 #endif
  36 };
  37
  38 /*
  39  * Page Extension can be considered as an extended mem_map.
  40  * A page_ext page is associated with every page descriptor. The
  41  * page_ext helps us add more information about the page.
  42  * All page_ext are allocated at boot or memory hotplug event,
  43  * then the page_ext for pfn always exists.
  44  */
  45 struct page_ext {
  46         unsigned long flags;
  47 };
  48
  49 extern void pgdat_page_ext_init(struct pglist_data *pgdat);
  50
  51 #ifdef CONFIG_SPARSEMEM
  52 static inline void page_ext_init_flatmem(void)
  53 {
  54 }
  55 extern void page_ext_init(void);
  56 #else
  57 extern void page_ext_init_flatmem(void);
  58 static inline void page_ext_init(void)
  59 {
  60 }
  61 #endif
  62
  63 struct page_ext *lookup_page_ext(struct page *page);
  64
  65 #else /* !CONFIG_PAGE_EXTENSION */
  66 struct page_ext;
  67
  68 static inline void pgdat_page_ext_init(struct pglist_data *pgdat)
  69 {
  70 }
  71
  72 static inline struct page_ext *lookup_page_ext(struct page *page)
  73 {
  74         return NULL;
  75 }
  76
  77 static inline void page_ext_init(void)
  78 {
  79 }
  80
  81 static inline void page_ext_init_flatmem(void)
  82 {
  83 }
  84 #endif /* CONFIG_PAGE_EXTENSION */
  85 #endif /* __LINUX_PAGE_EXT_H */