Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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
9struct 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 */
18struct 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 */