include/linux/page_ext.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __LINUX_PAGE_EXT_H
   3 #define __LINUX_PAGE_EXT_H
   4
   5 #include <linux/types.h>
   6 #include <linux/stacktrace.h>
   7 #include <linux/stackdepot.h>
   8
   9 struct pglist_data;
  10 struct page_ext_operations {
  11         size_t offset;
  12         size_t size;
  13         bool (*need)(void);
  14         void (*init)(void);
  15 };
  16
  17 #ifdef CONFIG_PAGE_EXTENSION
  18
  19 /*
  20  * page_ext->flags bits:
  21  *
  22  * PAGE_EXT_DEBUG_POISON is set for poisoned pages. This is used to
  23  * implement generic debug pagealloc feature. The pages are filled with
  24  * poison patterns and set this flag after free_pages(). The poisoned
  25  * pages are verified whether the patterns are not corrupted and clear
  26  * the flag before alloc_pages().
  27  */
  28
  29 enum page_ext_flags {
  30         PAGE_EXT_DEBUG_POISON,          /* Page is poisoned */
  31         PAGE_EXT_DEBUG_GUARD,
  32         PAGE_EXT_OWNER,
  33 #if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
  34         PAGE_EXT_YOUNG,
  35         PAGE_EXT_IDLE,
  36 #endif
  37 };
  38
  39 /*
  40  * Page Extension can be considered as an extended mem_map.
  41  * A page_ext page is associated with every page descriptor. The
  42  * page_ext helps us add more information about the page.
  43  * All page_ext are allocated at boot or memory hotplug event,
  44  * then the page_ext for pfn always exists.
  45  */
  46 struct page_ext {
  47         unsigned long flags;
  48 };
  49
  50 extern void pgdat_page_ext_init(struct pglist_data *pgdat);
  51
  52 #ifdef CONFIG_SPARSEMEM
  53 static inline void page_ext_init_flatmem(void)
  54 {
  55 }
  56 extern void page_ext_init(void);
  57 #else
  58 extern void page_ext_init_flatmem(void);
  59 static inline void page_ext_init(void)
  60 {
  61 }
  62 #endif
  63
  64 struct page_ext *lookup_page_ext(struct page *page);
  65
  66 #else /* !CONFIG_PAGE_EXTENSION */
  67 struct page_ext;
  68
  69 static inline void pgdat_page_ext_init(struct pglist_data *pgdat)
  70 {
  71 }
  72
  73 static inline struct page_ext *lookup_page_ext(struct page *page)
  74 {
  75         return NULL;
  76 }
  77
  78 static inline void page_ext_init(void)
  79 {
  80 }
  81
  82 static inline void page_ext_init_flatmem(void)
  83 {
  84 }
  85 #endif /* CONFIG_PAGE_EXTENSION */
  86 #endif /* __LINUX_PAGE_EXT_H */