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 */ 68