1 #ifndef _LINUX_RMAP_H 2 #define _LINUX_RMAP_H 3 /* 4 * Declarations for Reverse Mapping functions in mm/rmap.c 5 */ 6 7 #include <linux/list.h> 8 #include <linux/slab.h> 9 #include <linux/mm.h> 10 #include <linux/spinlock.h> 11 #include <linux/memcontrol.h> 12 13 /* 14 * The anon_vma heads a list of private "related" vmas, to scan if 15 * an anonymous page pointing to this anon_vma needs to be unmapped: 16 * the vmas on the list will be related by forking, or by splitting. 17 * 18 * Since vmas come and go as they are split and merged (particularly 19 * in mprotect), the mapping field of an anonymous page cannot point 20 * directly to a vma: instead it points to an anon_vma, on whose list 21 * the related vmas can be easily linked or unlinked. 22 * 23 * After unlinking the last vma on the list, we must garbage collect 24 * the anon_vma object itself: we're guaranteed no page can be 25 * pointing to this anon_vma once its vma list is empty. 26 */ 27 struct anon_vma { 28 spinlock_t lock; /* Serialize access to vma list */ 29 /* 30 * NOTE: the LSB of the head.next is set by 31 * mm_take_all_locks() _after_ taking the above lock. So the 32 * head must only be read/written after taking the above lock 33 * to be sure to see a valid next pointer. The LSB bit itself 34 * is serialized by a system wide lock only visible to 35 * mm_take_all_locks() (mm_all_locks_mutex). 36 */ 37 struct list_head head; /* List of private "related" vmas */ 38 }; 39 40 #ifdef CONFIG_MMU 41 42 static inline void anon_vma_lock(struct vm_area_struct *vma) 43 { 44 struct anon_vma *anon_vma = vma->anon_vma; 45 if (anon_vma) 46 spin_lock(&anon_vma->lock); 47 } 48 49 static inline void anon_vma_unlock(struct vm_area_struct *vma) 50 { 51 struct anon_vma *anon_vma = vma->anon_vma; 52 if (anon_vma) 53 spin_unlock(&anon_vma->lock); 54 } 55 56 /* 57 * anon_vma helper functions. 58 */ 59 void anon_vma_init(void); /* create anon_vma_cachep */ 60 int anon_vma_prepare(struct vm_area_struct *); 61 void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *); 62 void anon_vma_unlink(struct vm_area_struct *); 63 void anon_vma_link(struct vm_area_struct *); 64 void __anon_vma_link(struct vm_area_struct *); 65 66 extern struct anon_vma *page_lock_anon_vma(struct page *page); 67 extern void page_unlock_anon_vma(struct anon_vma *anon_vma); 68 69 /* 70 * rmap interfaces called when adding or removing pte of page 71 */ 72 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 73 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 74 void page_add_file_rmap(struct page *); 75 void page_remove_rmap(struct page *, struct vm_area_struct *); 76 77 #ifdef CONFIG_DEBUG_VM 78 void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address); 79 #else 80 static inline void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) 81 { 82 atomic_inc(&page->_mapcount); 83 } 84 #endif 85 86 /* 87 * Called from mm/vmscan.c to handle paging out 88 */ 89 int page_referenced(struct page *, int is_locked, struct mem_cgroup *cnt); 90 int try_to_unmap(struct page *, int ignore_refs); 91 92 /* 93 * Called from mm/filemap_xip.c to unmap empty zero page 94 */ 95 pte_t *page_check_address(struct page *, struct mm_struct *, 96 unsigned long, spinlock_t **, int); 97 98 /* 99 * Used by swapoff to help locate where page is expected in vma. 100 */ 101 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *); 102 103 /* 104 * Cleans the PTEs of shared mappings. 105 * (and since clean PTEs should also be readonly, write protects them too) 106 * 107 * returns the number of cleaned PTEs. 108 */ 109 int page_mkclean(struct page *); 110 111 #ifdef CONFIG_UNEVICTABLE_LRU 112 /* 113 * called in munlock()/munmap() path to check for other vmas holding 114 * the page mlocked. 115 */ 116 int try_to_munlock(struct page *); 117 #else 118 static inline int try_to_munlock(struct page *page) 119 { 120 return 0; /* a.k.a. SWAP_SUCCESS */ 121 } 122 #endif 123 124 #else /* !CONFIG_MMU */ 125 126 #define anon_vma_init() do {} while (0) 127 #define anon_vma_prepare(vma) (0) 128 #define anon_vma_link(vma) do {} while (0) 129 130 #define page_referenced(page,l,cnt) TestClearPageReferenced(page) 131 #define try_to_unmap(page, refs) SWAP_FAIL 132 133 static inline int page_mkclean(struct page *page) 134 { 135 return 0; 136 } 137 138 139 #endif /* CONFIG_MMU */ 140 141 /* 142 * Return values of try_to_unmap 143 */ 144 #define SWAP_SUCCESS 0 145 #define SWAP_AGAIN 1 146 #define SWAP_FAIL 2 147 #define SWAP_MLOCK 3 148 149 #endif /* _LINUX_RMAP_H */ 150