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 #if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
30 	PAGE_EXT_YOUNG,
31 	PAGE_EXT_IDLE,
32 #endif
33 };
34 
35 /*
36  * Page Extension can be considered as an extended mem_map.
37  * A page_ext page is associated with every page descriptor. The
38  * page_ext helps us add more information about the page.
39  * All page_ext are allocated at boot or memory hotplug event,
40  * then the page_ext for pfn always exists.
41  */
42 struct page_ext {
43 	unsigned long flags;
44 #ifdef CONFIG_PAGE_OWNER
45 	unsigned int order;
46 	gfp_t gfp_mask;
47 	unsigned int nr_entries;
48 	unsigned long trace_entries[8];
49 #endif
50 };
51 
52 extern void pgdat_page_ext_init(struct pglist_data *pgdat);
53 
54 #ifdef CONFIG_SPARSEMEM
page_ext_init_flatmem(void)55 static inline void page_ext_init_flatmem(void)
56 {
57 }
58 extern void page_ext_init(void);
59 #else
60 extern void page_ext_init_flatmem(void);
page_ext_init(void)61 static inline void page_ext_init(void)
62 {
63 }
64 #endif
65 
66 struct page_ext *lookup_page_ext(struct page *page);
67 
68 #else /* !CONFIG_PAGE_EXTENSION */
69 struct page_ext;
70 
pgdat_page_ext_init(struct pglist_data * pgdat)71 static inline void pgdat_page_ext_init(struct pglist_data *pgdat)
72 {
73 }
74 
lookup_page_ext(struct page * page)75 static inline struct page_ext *lookup_page_ext(struct page *page)
76 {
77 	return NULL;
78 }
79 
page_ext_init(void)80 static inline void page_ext_init(void)
81 {
82 }
83 
page_ext_init_flatmem(void)84 static inline void page_ext_init_flatmem(void)
85 {
86 }
87 #endif /* CONFIG_PAGE_EXTENSION */
88 #endif /* __LINUX_PAGE_EXT_H */
89