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