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5b99cd0e HC |
1 | #ifndef _LINUX_MM_TYPES_H |
2 | #define _LINUX_MM_TYPES_H | |
3 | ||
4 | #include <linux/types.h> | |
5 | #include <linux/threads.h> | |
6 | #include <linux/list.h> | |
7 | #include <linux/spinlock.h> | |
8 | ||
9 | struct address_space; | |
10 | ||
11 | /* | |
12 | * Each physical page in the system has a struct page associated with | |
13 | * it to keep track of whatever it is we are using the page for at the | |
14 | * moment. Note that we have no way to track which tasks are using | |
15 | * a page, though if it is a pagecache page, rmap structures can tell us | |
16 | * who is mapping it. | |
17 | */ | |
18 | struct page { | |
19 | unsigned long flags; /* Atomic flags, some possibly | |
20 | * updated asynchronously */ | |
21 | atomic_t _count; /* Usage count, see below. */ | |
22 | atomic_t _mapcount; /* Count of ptes mapped in mms, | |
23 | * to show when page is mapped | |
24 | * & limit reverse map searches. | |
25 | */ | |
26 | union { | |
27 | struct { | |
28 | unsigned long private; /* Mapping-private opaque data: | |
29 | * usually used for buffer_heads | |
30 | * if PagePrivate set; used for | |
31 | * swp_entry_t if PageSwapCache; | |
32 | * indicates order in the buddy | |
33 | * system if PG_buddy is set. | |
34 | */ | |
35 | struct address_space *mapping; /* If low bit clear, points to | |
36 | * inode address_space, or NULL. | |
37 | * If page mapped as anonymous | |
38 | * memory, low bit is set, and | |
39 | * it points to anon_vma object: | |
40 | * see PAGE_MAPPING_ANON below. | |
41 | */ | |
42 | }; | |
43 | #if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS | |
44 | spinlock_t ptl; | |
45 | #endif | |
46 | }; | |
47 | pgoff_t index; /* Our offset within mapping. */ | |
48 | struct list_head lru; /* Pageout list, eg. active_list | |
49 | * protected by zone->lru_lock ! | |
50 | */ | |
51 | /* | |
52 | * On machines where all RAM is mapped into kernel address space, | |
53 | * we can simply calculate the virtual address. On machines with | |
54 | * highmem some memory is mapped into kernel virtual memory | |
55 | * dynamically, so we need a place to store that address. | |
56 | * Note that this field could be 16 bits on x86 ... ;) | |
57 | * | |
58 | * Architectures with slow multiplication can define | |
59 | * WANT_PAGE_VIRTUAL in asm/page.h | |
60 | */ | |
61 | #if defined(WANT_PAGE_VIRTUAL) | |
62 | void *virtual; /* Kernel virtual address (NULL if | |
63 | not kmapped, ie. highmem) */ | |
64 | #endif /* WANT_PAGE_VIRTUAL */ | |
65 | }; | |
66 | ||
67 | #endif /* _LINUX_MM_TYPES_H */ |