Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1 | /* |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2 | * Memory merging support. |
| 3 | * |
| 4 | * This code enables dynamic sharing of identical pages found in different |
| 5 | * memory areas, even if they are not shared by fork() |
| 6 | * |
Izik Eidus | 36b2528 | 2009-09-21 17:02:06 -0700 | [diff] [blame] | 7 | * Copyright (C) 2008-2009 Red Hat, Inc. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 8 | * Authors: |
| 9 | * Izik Eidus |
| 10 | * Andrea Arcangeli |
| 11 | * Chris Wright |
Izik Eidus | 36b2528 | 2009-09-21 17:02:06 -0700 | [diff] [blame] | 12 | * Hugh Dickins |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 13 | * |
| 14 | * This work is licensed under the terms of the GNU GPL, version 2. |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 15 | */ |
| 16 | |
| 17 | #include <linux/errno.h> |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 18 | #include <linux/mm.h> |
| 19 | #include <linux/fs.h> |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 20 | #include <linux/mman.h> |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 21 | #include <linux/sched.h> |
| 22 | #include <linux/rwsem.h> |
| 23 | #include <linux/pagemap.h> |
| 24 | #include <linux/rmap.h> |
| 25 | #include <linux/spinlock.h> |
| 26 | #include <linux/jhash.h> |
| 27 | #include <linux/delay.h> |
| 28 | #include <linux/kthread.h> |
| 29 | #include <linux/wait.h> |
| 30 | #include <linux/slab.h> |
| 31 | #include <linux/rbtree.h> |
| 32 | #include <linux/mmu_notifier.h> |
Izik Eidus | 2c6854f | 2009-09-23 15:56:04 -0700 | [diff] [blame] | 33 | #include <linux/swap.h> |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 34 | #include <linux/ksm.h> |
| 35 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 36 | #include <asm/tlbflush.h> |
| 37 | |
| 38 | /* |
| 39 | * A few notes about the KSM scanning process, |
| 40 | * to make it easier to understand the data structures below: |
| 41 | * |
| 42 | * In order to reduce excessive scanning, KSM sorts the memory pages by their |
| 43 | * contents into a data structure that holds pointers to the pages' locations. |
| 44 | * |
| 45 | * Since the contents of the pages may change at any moment, KSM cannot just |
| 46 | * insert the pages into a normal sorted tree and expect it to find anything. |
| 47 | * Therefore KSM uses two data structures - the stable and the unstable tree. |
| 48 | * |
| 49 | * The stable tree holds pointers to all the merged pages (ksm pages), sorted |
| 50 | * by their contents. Because each such page is write-protected, searching on |
| 51 | * this tree is fully assured to be working (except when pages are unmapped), |
| 52 | * and therefore this tree is called the stable tree. |
| 53 | * |
| 54 | * In addition to the stable tree, KSM uses a second data structure called the |
| 55 | * unstable tree: this tree holds pointers to pages which have been found to |
| 56 | * be "unchanged for a period of time". The unstable tree sorts these pages |
| 57 | * by their contents, but since they are not write-protected, KSM cannot rely |
| 58 | * upon the unstable tree to work correctly - the unstable tree is liable to |
| 59 | * be corrupted as its contents are modified, and so it is called unstable. |
| 60 | * |
| 61 | * KSM solves this problem by several techniques: |
| 62 | * |
| 63 | * 1) The unstable tree is flushed every time KSM completes scanning all |
| 64 | * memory areas, and then the tree is rebuilt again from the beginning. |
| 65 | * 2) KSM will only insert into the unstable tree, pages whose hash value |
| 66 | * has not changed since the previous scan of all memory areas. |
| 67 | * 3) The unstable tree is a RedBlack Tree - so its balancing is based on the |
| 68 | * colors of the nodes and not on their contents, assuring that even when |
| 69 | * the tree gets "corrupted" it won't get out of balance, so scanning time |
| 70 | * remains the same (also, searching and inserting nodes in an rbtree uses |
| 71 | * the same algorithm, so we have no overhead when we flush and rebuild). |
| 72 | * 4) KSM never flushes the stable tree, which means that even if it were to |
| 73 | * take 10 attempts to find a page in the unstable tree, once it is found, |
| 74 | * it is secured in the stable tree. (When we scan a new page, we first |
| 75 | * compare it against the stable tree, and then against the unstable tree.) |
| 76 | */ |
| 77 | |
| 78 | /** |
| 79 | * struct mm_slot - ksm information per mm that is being scanned |
| 80 | * @link: link to the mm_slots hash list |
| 81 | * @mm_list: link into the mm_slots list, rooted in ksm_mm_head |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 82 | * @rmap_list: head for this mm_slot's singly-linked list of rmap_items |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 83 | * @mm: the mm that this information is valid for |
| 84 | */ |
| 85 | struct mm_slot { |
| 86 | struct hlist_node link; |
| 87 | struct list_head mm_list; |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 88 | struct rmap_item *rmap_list; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 89 | struct mm_struct *mm; |
| 90 | }; |
| 91 | |
| 92 | /** |
| 93 | * struct ksm_scan - cursor for scanning |
| 94 | * @mm_slot: the current mm_slot we are scanning |
| 95 | * @address: the next address inside that to be scanned |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 96 | * @rmap_list: link to the next rmap to be scanned in the rmap_list |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 97 | * @seqnr: count of completed full scans (needed when removing unstable node) |
| 98 | * |
| 99 | * There is only the one ksm_scan instance of this cursor structure. |
| 100 | */ |
| 101 | struct ksm_scan { |
| 102 | struct mm_slot *mm_slot; |
| 103 | unsigned long address; |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 104 | struct rmap_item **rmap_list; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 105 | unsigned long seqnr; |
| 106 | }; |
| 107 | |
| 108 | /** |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 109 | * struct stable_node - node of the stable rbtree |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 110 | * @page: pointer to struct page of the ksm page |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 111 | * @node: rb node of this ksm page in the stable tree |
| 112 | * @hlist: hlist head of rmap_items using this ksm page |
| 113 | */ |
| 114 | struct stable_node { |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 115 | struct page *page; |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 116 | struct rb_node node; |
| 117 | struct hlist_head hlist; |
| 118 | }; |
| 119 | |
| 120 | /** |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 121 | * struct rmap_item - reverse mapping item for virtual addresses |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 122 | * @rmap_list: next rmap_item in mm_slot's singly-linked rmap_list |
| 123 | * @filler: unused space we're making available in this patch |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 124 | * @mm: the memory structure this rmap_item is pointing into |
| 125 | * @address: the virtual address this rmap_item tracks (+ flags in low bits) |
| 126 | * @oldchecksum: previous checksum of the page at that virtual address |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 127 | * @node: rb node of this rmap_item in the unstable tree |
| 128 | * @head: pointer to stable_node heading this list in the stable tree |
| 129 | * @hlist: link into hlist of rmap_items hanging off that stable_node |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 130 | */ |
| 131 | struct rmap_item { |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 132 | struct rmap_item *rmap_list; |
| 133 | unsigned long filler; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 134 | struct mm_struct *mm; |
| 135 | unsigned long address; /* + low bits used for flags below */ |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 136 | unsigned int oldchecksum; /* when unstable */ |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 137 | union { |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 138 | struct rb_node node; /* when node of unstable tree */ |
| 139 | struct { /* when listed from stable tree */ |
| 140 | struct stable_node *head; |
| 141 | struct hlist_node hlist; |
| 142 | }; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 143 | }; |
| 144 | }; |
| 145 | |
| 146 | #define SEQNR_MASK 0x0ff /* low bits of unstable tree seqnr */ |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 147 | #define UNSTABLE_FLAG 0x100 /* is a node of the unstable tree */ |
| 148 | #define STABLE_FLAG 0x200 /* is listed from the stable tree */ |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 149 | |
| 150 | /* The stable and unstable tree heads */ |
| 151 | static struct rb_root root_stable_tree = RB_ROOT; |
| 152 | static struct rb_root root_unstable_tree = RB_ROOT; |
| 153 | |
| 154 | #define MM_SLOTS_HASH_HEADS 1024 |
| 155 | static struct hlist_head *mm_slots_hash; |
| 156 | |
| 157 | static struct mm_slot ksm_mm_head = { |
| 158 | .mm_list = LIST_HEAD_INIT(ksm_mm_head.mm_list), |
| 159 | }; |
| 160 | static struct ksm_scan ksm_scan = { |
| 161 | .mm_slot = &ksm_mm_head, |
| 162 | }; |
| 163 | |
| 164 | static struct kmem_cache *rmap_item_cache; |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 165 | static struct kmem_cache *stable_node_cache; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 166 | static struct kmem_cache *mm_slot_cache; |
| 167 | |
| 168 | /* The number of nodes in the stable tree */ |
Hugh Dickins | b402826 | 2009-09-21 17:02:09 -0700 | [diff] [blame] | 169 | static unsigned long ksm_pages_shared; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 170 | |
Hugh Dickins | e178dfd | 2009-09-21 17:02:10 -0700 | [diff] [blame] | 171 | /* The number of page slots additionally sharing those nodes */ |
Hugh Dickins | b402826 | 2009-09-21 17:02:09 -0700 | [diff] [blame] | 172 | static unsigned long ksm_pages_sharing; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 173 | |
Hugh Dickins | 473b0ce | 2009-09-21 17:02:11 -0700 | [diff] [blame] | 174 | /* The number of nodes in the unstable tree */ |
| 175 | static unsigned long ksm_pages_unshared; |
| 176 | |
| 177 | /* The number of rmap_items in use: to calculate pages_volatile */ |
| 178 | static unsigned long ksm_rmap_items; |
| 179 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 180 | /* Limit on the number of unswappable pages used */ |
Izik Eidus | 2c6854f | 2009-09-23 15:56:04 -0700 | [diff] [blame] | 181 | static unsigned long ksm_max_kernel_pages; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 182 | |
| 183 | /* Number of pages ksmd should scan in one batch */ |
Izik Eidus | 2c6854f | 2009-09-23 15:56:04 -0700 | [diff] [blame] | 184 | static unsigned int ksm_thread_pages_to_scan = 100; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 185 | |
| 186 | /* Milliseconds ksmd should sleep between batches */ |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 187 | static unsigned int ksm_thread_sleep_millisecs = 20; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 188 | |
| 189 | #define KSM_RUN_STOP 0 |
| 190 | #define KSM_RUN_MERGE 1 |
| 191 | #define KSM_RUN_UNMERGE 2 |
Izik Eidus | 2c6854f | 2009-09-23 15:56:04 -0700 | [diff] [blame] | 192 | static unsigned int ksm_run = KSM_RUN_STOP; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 193 | |
| 194 | static DECLARE_WAIT_QUEUE_HEAD(ksm_thread_wait); |
| 195 | static DEFINE_MUTEX(ksm_thread_mutex); |
| 196 | static DEFINE_SPINLOCK(ksm_mmlist_lock); |
| 197 | |
| 198 | #define KSM_KMEM_CACHE(__struct, __flags) kmem_cache_create("ksm_"#__struct,\ |
| 199 | sizeof(struct __struct), __alignof__(struct __struct),\ |
| 200 | (__flags), NULL) |
| 201 | |
| 202 | static int __init ksm_slab_init(void) |
| 203 | { |
| 204 | rmap_item_cache = KSM_KMEM_CACHE(rmap_item, 0); |
| 205 | if (!rmap_item_cache) |
| 206 | goto out; |
| 207 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 208 | stable_node_cache = KSM_KMEM_CACHE(stable_node, 0); |
| 209 | if (!stable_node_cache) |
| 210 | goto out_free1; |
| 211 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 212 | mm_slot_cache = KSM_KMEM_CACHE(mm_slot, 0); |
| 213 | if (!mm_slot_cache) |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 214 | goto out_free2; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 215 | |
| 216 | return 0; |
| 217 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 218 | out_free2: |
| 219 | kmem_cache_destroy(stable_node_cache); |
| 220 | out_free1: |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 221 | kmem_cache_destroy(rmap_item_cache); |
| 222 | out: |
| 223 | return -ENOMEM; |
| 224 | } |
| 225 | |
| 226 | static void __init ksm_slab_free(void) |
| 227 | { |
| 228 | kmem_cache_destroy(mm_slot_cache); |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 229 | kmem_cache_destroy(stable_node_cache); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 230 | kmem_cache_destroy(rmap_item_cache); |
| 231 | mm_slot_cache = NULL; |
| 232 | } |
| 233 | |
| 234 | static inline struct rmap_item *alloc_rmap_item(void) |
| 235 | { |
Hugh Dickins | 473b0ce | 2009-09-21 17:02:11 -0700 | [diff] [blame] | 236 | struct rmap_item *rmap_item; |
| 237 | |
| 238 | rmap_item = kmem_cache_zalloc(rmap_item_cache, GFP_KERNEL); |
| 239 | if (rmap_item) |
| 240 | ksm_rmap_items++; |
| 241 | return rmap_item; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 242 | } |
| 243 | |
| 244 | static inline void free_rmap_item(struct rmap_item *rmap_item) |
| 245 | { |
Hugh Dickins | 473b0ce | 2009-09-21 17:02:11 -0700 | [diff] [blame] | 246 | ksm_rmap_items--; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 247 | rmap_item->mm = NULL; /* debug safety */ |
| 248 | kmem_cache_free(rmap_item_cache, rmap_item); |
| 249 | } |
| 250 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 251 | static inline struct stable_node *alloc_stable_node(void) |
| 252 | { |
| 253 | return kmem_cache_alloc(stable_node_cache, GFP_KERNEL); |
| 254 | } |
| 255 | |
| 256 | static inline void free_stable_node(struct stable_node *stable_node) |
| 257 | { |
| 258 | kmem_cache_free(stable_node_cache, stable_node); |
| 259 | } |
| 260 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 261 | static inline struct mm_slot *alloc_mm_slot(void) |
| 262 | { |
| 263 | if (!mm_slot_cache) /* initialization failed */ |
| 264 | return NULL; |
| 265 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); |
| 266 | } |
| 267 | |
| 268 | static inline void free_mm_slot(struct mm_slot *mm_slot) |
| 269 | { |
| 270 | kmem_cache_free(mm_slot_cache, mm_slot); |
| 271 | } |
| 272 | |
| 273 | static int __init mm_slots_hash_init(void) |
| 274 | { |
| 275 | mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head), |
| 276 | GFP_KERNEL); |
| 277 | if (!mm_slots_hash) |
| 278 | return -ENOMEM; |
| 279 | return 0; |
| 280 | } |
| 281 | |
| 282 | static void __init mm_slots_hash_free(void) |
| 283 | { |
| 284 | kfree(mm_slots_hash); |
| 285 | } |
| 286 | |
| 287 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) |
| 288 | { |
| 289 | struct mm_slot *mm_slot; |
| 290 | struct hlist_head *bucket; |
| 291 | struct hlist_node *node; |
| 292 | |
| 293 | bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct)) |
| 294 | % MM_SLOTS_HASH_HEADS]; |
| 295 | hlist_for_each_entry(mm_slot, node, bucket, link) { |
| 296 | if (mm == mm_slot->mm) |
| 297 | return mm_slot; |
| 298 | } |
| 299 | return NULL; |
| 300 | } |
| 301 | |
| 302 | static void insert_to_mm_slots_hash(struct mm_struct *mm, |
| 303 | struct mm_slot *mm_slot) |
| 304 | { |
| 305 | struct hlist_head *bucket; |
| 306 | |
| 307 | bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct)) |
| 308 | % MM_SLOTS_HASH_HEADS]; |
| 309 | mm_slot->mm = mm; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 310 | hlist_add_head(&mm_slot->link, bucket); |
| 311 | } |
| 312 | |
| 313 | static inline int in_stable_tree(struct rmap_item *rmap_item) |
| 314 | { |
| 315 | return rmap_item->address & STABLE_FLAG; |
| 316 | } |
| 317 | |
| 318 | /* |
Hugh Dickins | a913e18 | 2009-09-21 17:02:26 -0700 | [diff] [blame] | 319 | * ksmd, and unmerge_and_remove_all_rmap_items(), must not touch an mm's |
| 320 | * page tables after it has passed through ksm_exit() - which, if necessary, |
| 321 | * takes mmap_sem briefly to serialize against them. ksm_exit() does not set |
| 322 | * a special flag: they can just back out as soon as mm_users goes to zero. |
| 323 | * ksm_test_exit() is used throughout to make this test for exit: in some |
| 324 | * places for correctness, in some places just to avoid unnecessary work. |
| 325 | */ |
| 326 | static inline bool ksm_test_exit(struct mm_struct *mm) |
| 327 | { |
| 328 | return atomic_read(&mm->mm_users) == 0; |
| 329 | } |
| 330 | |
| 331 | /* |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 332 | * We use break_ksm to break COW on a ksm page: it's a stripped down |
| 333 | * |
| 334 | * if (get_user_pages(current, mm, addr, 1, 1, 1, &page, NULL) == 1) |
| 335 | * put_page(page); |
| 336 | * |
| 337 | * but taking great care only to touch a ksm page, in a VM_MERGEABLE vma, |
| 338 | * in case the application has unmapped and remapped mm,addr meanwhile. |
| 339 | * Could a ksm page appear anywhere else? Actually yes, in a VM_PFNMAP |
| 340 | * mmap of /dev/mem or /dev/kmem, where we would not want to touch it. |
| 341 | */ |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 342 | static int break_ksm(struct vm_area_struct *vma, unsigned long addr) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 343 | { |
| 344 | struct page *page; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 345 | int ret = 0; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 346 | |
| 347 | do { |
| 348 | cond_resched(); |
| 349 | page = follow_page(vma, addr, FOLL_GET); |
| 350 | if (!page) |
| 351 | break; |
| 352 | if (PageKsm(page)) |
| 353 | ret = handle_mm_fault(vma->vm_mm, vma, addr, |
| 354 | FAULT_FLAG_WRITE); |
| 355 | else |
| 356 | ret = VM_FAULT_WRITE; |
| 357 | put_page(page); |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 358 | } while (!(ret & (VM_FAULT_WRITE | VM_FAULT_SIGBUS | VM_FAULT_OOM))); |
| 359 | /* |
| 360 | * We must loop because handle_mm_fault() may back out if there's |
| 361 | * any difficulty e.g. if pte accessed bit gets updated concurrently. |
| 362 | * |
| 363 | * VM_FAULT_WRITE is what we have been hoping for: it indicates that |
| 364 | * COW has been broken, even if the vma does not permit VM_WRITE; |
| 365 | * but note that a concurrent fault might break PageKsm for us. |
| 366 | * |
| 367 | * VM_FAULT_SIGBUS could occur if we race with truncation of the |
| 368 | * backing file, which also invalidates anonymous pages: that's |
| 369 | * okay, that truncation will have unmapped the PageKsm for us. |
| 370 | * |
| 371 | * VM_FAULT_OOM: at the time of writing (late July 2009), setting |
| 372 | * aside mem_cgroup limits, VM_FAULT_OOM would only be set if the |
| 373 | * current task has TIF_MEMDIE set, and will be OOM killed on return |
| 374 | * to user; and ksmd, having no mm, would never be chosen for that. |
| 375 | * |
| 376 | * But if the mm is in a limited mem_cgroup, then the fault may fail |
| 377 | * with VM_FAULT_OOM even if the current task is not TIF_MEMDIE; and |
| 378 | * even ksmd can fail in this way - though it's usually breaking ksm |
| 379 | * just to undo a merge it made a moment before, so unlikely to oom. |
| 380 | * |
| 381 | * That's a pity: we might therefore have more kernel pages allocated |
| 382 | * than we're counting as nodes in the stable tree; but ksm_do_scan |
| 383 | * will retry to break_cow on each pass, so should recover the page |
| 384 | * in due course. The important thing is to not let VM_MERGEABLE |
| 385 | * be cleared while any such pages might remain in the area. |
| 386 | */ |
| 387 | return (ret & VM_FAULT_OOM) ? -ENOMEM : 0; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 388 | } |
| 389 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 390 | static void break_cow(struct rmap_item *rmap_item) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 391 | { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 392 | struct mm_struct *mm = rmap_item->mm; |
| 393 | unsigned long addr = rmap_item->address; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 394 | struct vm_area_struct *vma; |
| 395 | |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 396 | down_read(&mm->mmap_sem); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 397 | if (ksm_test_exit(mm)) |
| 398 | goto out; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 399 | vma = find_vma(mm, addr); |
| 400 | if (!vma || vma->vm_start > addr) |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 401 | goto out; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 402 | if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma) |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 403 | goto out; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 404 | break_ksm(vma, addr); |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 405 | out: |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 406 | up_read(&mm->mmap_sem); |
| 407 | } |
| 408 | |
| 409 | static struct page *get_mergeable_page(struct rmap_item *rmap_item) |
| 410 | { |
| 411 | struct mm_struct *mm = rmap_item->mm; |
| 412 | unsigned long addr = rmap_item->address; |
| 413 | struct vm_area_struct *vma; |
| 414 | struct page *page; |
| 415 | |
| 416 | down_read(&mm->mmap_sem); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 417 | if (ksm_test_exit(mm)) |
| 418 | goto out; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 419 | vma = find_vma(mm, addr); |
| 420 | if (!vma || vma->vm_start > addr) |
| 421 | goto out; |
| 422 | if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma) |
| 423 | goto out; |
| 424 | |
| 425 | page = follow_page(vma, addr, FOLL_GET); |
| 426 | if (!page) |
| 427 | goto out; |
| 428 | if (PageAnon(page)) { |
| 429 | flush_anon_page(vma, page, addr); |
| 430 | flush_dcache_page(page); |
| 431 | } else { |
| 432 | put_page(page); |
| 433 | out: page = NULL; |
| 434 | } |
| 435 | up_read(&mm->mmap_sem); |
| 436 | return page; |
| 437 | } |
| 438 | |
| 439 | /* |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 440 | * Removing rmap_item from stable or unstable tree. |
| 441 | * This function will clean the information from the stable/unstable tree. |
| 442 | */ |
| 443 | static void remove_rmap_item_from_tree(struct rmap_item *rmap_item) |
| 444 | { |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 445 | if (rmap_item->address & STABLE_FLAG) { |
| 446 | struct stable_node *stable_node; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 447 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 448 | stable_node = rmap_item->head; |
| 449 | hlist_del(&rmap_item->hlist); |
| 450 | if (stable_node->hlist.first) |
Hugh Dickins | e178dfd | 2009-09-21 17:02:10 -0700 | [diff] [blame] | 451 | ksm_pages_sharing--; |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 452 | else { |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 453 | set_page_stable_node(stable_node->page, NULL); |
| 454 | put_page(stable_node->page); |
| 455 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 456 | rb_erase(&stable_node->node, &root_stable_tree); |
| 457 | free_stable_node(stable_node); |
| 458 | ksm_pages_shared--; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 459 | } |
| 460 | |
Hugh Dickins | 93d1771 | 2009-12-14 17:59:16 -0800 | [diff] [blame] | 461 | rmap_item->address &= PAGE_MASK; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 462 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 463 | } else if (rmap_item->address & UNSTABLE_FLAG) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 464 | unsigned char age; |
| 465 | /* |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 466 | * Usually ksmd can and must skip the rb_erase, because |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 467 | * root_unstable_tree was already reset to RB_ROOT. |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 468 | * But be careful when an mm is exiting: do the rb_erase |
| 469 | * if this rmap_item was inserted by this scan, rather |
| 470 | * than left over from before. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 471 | */ |
| 472 | age = (unsigned char)(ksm_scan.seqnr - rmap_item->address); |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 473 | BUG_ON(age > 1); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 474 | if (!age) |
| 475 | rb_erase(&rmap_item->node, &root_unstable_tree); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 476 | |
Hugh Dickins | 93d1771 | 2009-12-14 17:59:16 -0800 | [diff] [blame] | 477 | ksm_pages_unshared--; |
| 478 | rmap_item->address &= PAGE_MASK; |
| 479 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 480 | |
| 481 | cond_resched(); /* we're called from many long loops */ |
| 482 | } |
| 483 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 484 | static void remove_trailing_rmap_items(struct mm_slot *mm_slot, |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 485 | struct rmap_item **rmap_list) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 486 | { |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 487 | while (*rmap_list) { |
| 488 | struct rmap_item *rmap_item = *rmap_list; |
| 489 | *rmap_list = rmap_item->rmap_list; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 490 | remove_rmap_item_from_tree(rmap_item); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 491 | free_rmap_item(rmap_item); |
| 492 | } |
| 493 | } |
| 494 | |
| 495 | /* |
| 496 | * Though it's very tempting to unmerge in_stable_tree(rmap_item)s rather |
| 497 | * than check every pte of a given vma, the locking doesn't quite work for |
| 498 | * that - an rmap_item is assigned to the stable tree after inserting ksm |
| 499 | * page and upping mmap_sem. Nor does it fit with the way we skip dup'ing |
| 500 | * rmap_items from parent to child at fork time (so as not to waste time |
| 501 | * if exit comes before the next scan reaches it). |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 502 | * |
| 503 | * Similarly, although we'd like to remove rmap_items (so updating counts |
| 504 | * and freeing memory) when unmerging an area, it's easier to leave that |
| 505 | * to the next pass of ksmd - consider, for example, how ksmd might be |
| 506 | * in cmp_and_merge_page on one of the rmap_items we would be removing. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 507 | */ |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 508 | static int unmerge_ksm_pages(struct vm_area_struct *vma, |
| 509 | unsigned long start, unsigned long end) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 510 | { |
| 511 | unsigned long addr; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 512 | int err = 0; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 513 | |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 514 | for (addr = start; addr < end && !err; addr += PAGE_SIZE) { |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 515 | if (ksm_test_exit(vma->vm_mm)) |
| 516 | break; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 517 | if (signal_pending(current)) |
| 518 | err = -ERESTARTSYS; |
| 519 | else |
| 520 | err = break_ksm(vma, addr); |
| 521 | } |
| 522 | return err; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 523 | } |
| 524 | |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 525 | #ifdef CONFIG_SYSFS |
| 526 | /* |
| 527 | * Only called through the sysfs control interface: |
| 528 | */ |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 529 | static int unmerge_and_remove_all_rmap_items(void) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 530 | { |
| 531 | struct mm_slot *mm_slot; |
| 532 | struct mm_struct *mm; |
| 533 | struct vm_area_struct *vma; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 534 | int err = 0; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 535 | |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 536 | spin_lock(&ksm_mmlist_lock); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 537 | ksm_scan.mm_slot = list_entry(ksm_mm_head.mm_list.next, |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 538 | struct mm_slot, mm_list); |
| 539 | spin_unlock(&ksm_mmlist_lock); |
| 540 | |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 541 | for (mm_slot = ksm_scan.mm_slot; |
| 542 | mm_slot != &ksm_mm_head; mm_slot = ksm_scan.mm_slot) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 543 | mm = mm_slot->mm; |
| 544 | down_read(&mm->mmap_sem); |
| 545 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 546 | if (ksm_test_exit(mm)) |
| 547 | break; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 548 | if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma) |
| 549 | continue; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 550 | err = unmerge_ksm_pages(vma, |
| 551 | vma->vm_start, vma->vm_end); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 552 | if (err) |
| 553 | goto error; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 554 | } |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 555 | |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 556 | remove_trailing_rmap_items(mm_slot, &mm_slot->rmap_list); |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 557 | |
| 558 | spin_lock(&ksm_mmlist_lock); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 559 | ksm_scan.mm_slot = list_entry(mm_slot->mm_list.next, |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 560 | struct mm_slot, mm_list); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 561 | if (ksm_test_exit(mm)) { |
| 562 | hlist_del(&mm_slot->link); |
| 563 | list_del(&mm_slot->mm_list); |
| 564 | spin_unlock(&ksm_mmlist_lock); |
| 565 | |
| 566 | free_mm_slot(mm_slot); |
| 567 | clear_bit(MMF_VM_MERGEABLE, &mm->flags); |
| 568 | up_read(&mm->mmap_sem); |
| 569 | mmdrop(mm); |
| 570 | } else { |
| 571 | spin_unlock(&ksm_mmlist_lock); |
| 572 | up_read(&mm->mmap_sem); |
| 573 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 574 | } |
| 575 | |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 576 | ksm_scan.seqnr = 0; |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 577 | return 0; |
| 578 | |
| 579 | error: |
| 580 | up_read(&mm->mmap_sem); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 581 | spin_lock(&ksm_mmlist_lock); |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 582 | ksm_scan.mm_slot = &ksm_mm_head; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 583 | spin_unlock(&ksm_mmlist_lock); |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 584 | return err; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 585 | } |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 586 | #endif /* CONFIG_SYSFS */ |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 587 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 588 | static u32 calc_checksum(struct page *page) |
| 589 | { |
| 590 | u32 checksum; |
| 591 | void *addr = kmap_atomic(page, KM_USER0); |
| 592 | checksum = jhash2(addr, PAGE_SIZE / 4, 17); |
| 593 | kunmap_atomic(addr, KM_USER0); |
| 594 | return checksum; |
| 595 | } |
| 596 | |
| 597 | static int memcmp_pages(struct page *page1, struct page *page2) |
| 598 | { |
| 599 | char *addr1, *addr2; |
| 600 | int ret; |
| 601 | |
| 602 | addr1 = kmap_atomic(page1, KM_USER0); |
| 603 | addr2 = kmap_atomic(page2, KM_USER1); |
| 604 | ret = memcmp(addr1, addr2, PAGE_SIZE); |
| 605 | kunmap_atomic(addr2, KM_USER1); |
| 606 | kunmap_atomic(addr1, KM_USER0); |
| 607 | return ret; |
| 608 | } |
| 609 | |
| 610 | static inline int pages_identical(struct page *page1, struct page *page2) |
| 611 | { |
| 612 | return !memcmp_pages(page1, page2); |
| 613 | } |
| 614 | |
| 615 | static int write_protect_page(struct vm_area_struct *vma, struct page *page, |
| 616 | pte_t *orig_pte) |
| 617 | { |
| 618 | struct mm_struct *mm = vma->vm_mm; |
| 619 | unsigned long addr; |
| 620 | pte_t *ptep; |
| 621 | spinlock_t *ptl; |
| 622 | int swapped; |
| 623 | int err = -EFAULT; |
| 624 | |
| 625 | addr = page_address_in_vma(page, vma); |
| 626 | if (addr == -EFAULT) |
| 627 | goto out; |
| 628 | |
| 629 | ptep = page_check_address(page, mm, addr, &ptl, 0); |
| 630 | if (!ptep) |
| 631 | goto out; |
| 632 | |
| 633 | if (pte_write(*ptep)) { |
| 634 | pte_t entry; |
| 635 | |
| 636 | swapped = PageSwapCache(page); |
| 637 | flush_cache_page(vma, addr, page_to_pfn(page)); |
| 638 | /* |
| 639 | * Ok this is tricky, when get_user_pages_fast() run it doesnt |
| 640 | * take any lock, therefore the check that we are going to make |
| 641 | * with the pagecount against the mapcount is racey and |
| 642 | * O_DIRECT can happen right after the check. |
| 643 | * So we clear the pte and flush the tlb before the check |
| 644 | * this assure us that no O_DIRECT can happen after the check |
| 645 | * or in the middle of the check. |
| 646 | */ |
| 647 | entry = ptep_clear_flush(vma, addr, ptep); |
| 648 | /* |
| 649 | * Check that no O_DIRECT or similar I/O is in progress on the |
| 650 | * page |
| 651 | */ |
Hugh Dickins | 31e855e | 2009-12-14 17:59:17 -0800 | [diff] [blame] | 652 | if (page_mapcount(page) + 1 + swapped != page_count(page)) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 653 | set_pte_at_notify(mm, addr, ptep, entry); |
| 654 | goto out_unlock; |
| 655 | } |
| 656 | entry = pte_wrprotect(entry); |
| 657 | set_pte_at_notify(mm, addr, ptep, entry); |
| 658 | } |
| 659 | *orig_pte = *ptep; |
| 660 | err = 0; |
| 661 | |
| 662 | out_unlock: |
| 663 | pte_unmap_unlock(ptep, ptl); |
| 664 | out: |
| 665 | return err; |
| 666 | } |
| 667 | |
| 668 | /** |
| 669 | * replace_page - replace page in vma by new ksm page |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 670 | * @vma: vma that holds the pte pointing to page |
| 671 | * @page: the page we are replacing by kpage |
| 672 | * @kpage: the ksm page we replace page by |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 673 | * @orig_pte: the original value of the pte |
| 674 | * |
| 675 | * Returns 0 on success, -EFAULT on failure. |
| 676 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 677 | static int replace_page(struct vm_area_struct *vma, struct page *page, |
| 678 | struct page *kpage, pte_t orig_pte) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 679 | { |
| 680 | struct mm_struct *mm = vma->vm_mm; |
| 681 | pgd_t *pgd; |
| 682 | pud_t *pud; |
| 683 | pmd_t *pmd; |
| 684 | pte_t *ptep; |
| 685 | spinlock_t *ptl; |
| 686 | unsigned long addr; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 687 | int err = -EFAULT; |
| 688 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 689 | addr = page_address_in_vma(page, vma); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 690 | if (addr == -EFAULT) |
| 691 | goto out; |
| 692 | |
| 693 | pgd = pgd_offset(mm, addr); |
| 694 | if (!pgd_present(*pgd)) |
| 695 | goto out; |
| 696 | |
| 697 | pud = pud_offset(pgd, addr); |
| 698 | if (!pud_present(*pud)) |
| 699 | goto out; |
| 700 | |
| 701 | pmd = pmd_offset(pud, addr); |
| 702 | if (!pmd_present(*pmd)) |
| 703 | goto out; |
| 704 | |
| 705 | ptep = pte_offset_map_lock(mm, pmd, addr, &ptl); |
| 706 | if (!pte_same(*ptep, orig_pte)) { |
| 707 | pte_unmap_unlock(ptep, ptl); |
| 708 | goto out; |
| 709 | } |
| 710 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 711 | get_page(kpage); |
| 712 | page_add_ksm_rmap(kpage); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 713 | |
| 714 | flush_cache_page(vma, addr, pte_pfn(*ptep)); |
| 715 | ptep_clear_flush(vma, addr, ptep); |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 716 | set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot)); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 717 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 718 | page_remove_rmap(page); |
| 719 | put_page(page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 720 | |
| 721 | pte_unmap_unlock(ptep, ptl); |
| 722 | err = 0; |
| 723 | out: |
| 724 | return err; |
| 725 | } |
| 726 | |
| 727 | /* |
| 728 | * try_to_merge_one_page - take two pages and merge them into one |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 729 | * @vma: the vma that holds the pte pointing to page |
| 730 | * @page: the PageAnon page that we want to replace with kpage |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 731 | * @kpage: the PageKsm page that we want to map instead of page |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 732 | * |
| 733 | * This function returns 0 if the pages were merged, -EFAULT otherwise. |
| 734 | */ |
| 735 | static int try_to_merge_one_page(struct vm_area_struct *vma, |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 736 | struct page *page, struct page *kpage) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 737 | { |
| 738 | pte_t orig_pte = __pte(0); |
| 739 | int err = -EFAULT; |
| 740 | |
| 741 | if (!(vma->vm_flags & VM_MERGEABLE)) |
| 742 | goto out; |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 743 | if (!PageAnon(page)) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 744 | goto out; |
| 745 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 746 | /* |
| 747 | * We need the page lock to read a stable PageSwapCache in |
| 748 | * write_protect_page(). We use trylock_page() instead of |
| 749 | * lock_page() because we don't want to wait here - we |
| 750 | * prefer to continue scanning and merging different pages, |
| 751 | * then come back to this page when it is unlocked. |
| 752 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 753 | if (!trylock_page(page)) |
Hugh Dickins | 31e855e | 2009-12-14 17:59:17 -0800 | [diff] [blame] | 754 | goto out; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 755 | /* |
| 756 | * If this anonymous page is mapped only here, its pte may need |
| 757 | * to be write-protected. If it's mapped elsewhere, all of its |
| 758 | * ptes are necessarily already write-protected. But in either |
| 759 | * case, we need to lock and check page_count is not raised. |
| 760 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 761 | if (write_protect_page(vma, page, &orig_pte) == 0 && |
| 762 | pages_identical(page, kpage)) |
| 763 | err = replace_page(vma, page, kpage, orig_pte); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 764 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 765 | unlock_page(page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 766 | out: |
| 767 | return err; |
| 768 | } |
| 769 | |
| 770 | /* |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 771 | * try_to_merge_with_ksm_page - like try_to_merge_two_pages, |
| 772 | * but no new kernel page is allocated: kpage must already be a ksm page. |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 773 | * |
| 774 | * This function returns 0 if the pages were merged, -EFAULT otherwise. |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 775 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 776 | static int try_to_merge_with_ksm_page(struct rmap_item *rmap_item, |
| 777 | struct page *page, struct page *kpage) |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 778 | { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 779 | struct mm_struct *mm = rmap_item->mm; |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 780 | struct vm_area_struct *vma; |
| 781 | int err = -EFAULT; |
| 782 | |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 783 | if (page == kpage) /* ksm page forked */ |
| 784 | return 0; |
| 785 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 786 | down_read(&mm->mmap_sem); |
| 787 | if (ksm_test_exit(mm)) |
| 788 | goto out; |
| 789 | vma = find_vma(mm, rmap_item->address); |
| 790 | if (!vma || vma->vm_start > rmap_item->address) |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 791 | goto out; |
| 792 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 793 | err = try_to_merge_one_page(vma, page, kpage); |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 794 | out: |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 795 | up_read(&mm->mmap_sem); |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 796 | return err; |
| 797 | } |
| 798 | |
| 799 | /* |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 800 | * try_to_merge_two_pages - take two identical pages and prepare them |
| 801 | * to be merged into one page. |
| 802 | * |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 803 | * This function returns the kpage if we successfully merged two identical |
| 804 | * pages into one ksm page, NULL otherwise. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 805 | * |
| 806 | * Note that this function allocates a new kernel page: if one of the pages |
| 807 | * is already a ksm page, try_to_merge_with_ksm_page should be used. |
| 808 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 809 | static struct page *try_to_merge_two_pages(struct rmap_item *rmap_item, |
| 810 | struct page *page, |
| 811 | struct rmap_item *tree_rmap_item, |
| 812 | struct page *tree_page) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 813 | { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 814 | struct mm_struct *mm = rmap_item->mm; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 815 | struct vm_area_struct *vma; |
| 816 | struct page *kpage; |
| 817 | int err = -EFAULT; |
| 818 | |
| 819 | /* |
| 820 | * The number of nodes in the stable tree |
| 821 | * is the number of kernel pages that we hold. |
| 822 | */ |
| 823 | if (ksm_max_kernel_pages && |
Hugh Dickins | b402826 | 2009-09-21 17:02:09 -0700 | [diff] [blame] | 824 | ksm_max_kernel_pages <= ksm_pages_shared) |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 825 | return NULL; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 826 | |
| 827 | kpage = alloc_page(GFP_HIGHUSER); |
| 828 | if (!kpage) |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 829 | return NULL; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 830 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 831 | down_read(&mm->mmap_sem); |
| 832 | if (ksm_test_exit(mm)) |
| 833 | goto up; |
| 834 | vma = find_vma(mm, rmap_item->address); |
| 835 | if (!vma || vma->vm_start > rmap_item->address) |
| 836 | goto up; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 837 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 838 | copy_user_highpage(kpage, page, rmap_item->address, vma); |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 839 | |
| 840 | set_page_stable_node(kpage, NULL); /* mark it PageKsm */ |
| 841 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 842 | err = try_to_merge_one_page(vma, page, kpage); |
| 843 | up: |
| 844 | up_read(&mm->mmap_sem); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 845 | |
| 846 | if (!err) { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 847 | err = try_to_merge_with_ksm_page(tree_rmap_item, |
| 848 | tree_page, kpage); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 849 | /* |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 850 | * If that fails, we have a ksm page with only one pte |
| 851 | * pointing to it: so break it. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 852 | */ |
| 853 | if (err) |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 854 | break_cow(rmap_item); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 855 | } |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 856 | if (err) { |
| 857 | put_page(kpage); |
| 858 | kpage = NULL; |
| 859 | } |
| 860 | return kpage; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 861 | } |
| 862 | |
| 863 | /* |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 864 | * stable_tree_search - search for page inside the stable tree |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 865 | * |
| 866 | * This function checks if there is a page inside the stable tree |
| 867 | * with identical content to the page that we are scanning right now. |
| 868 | * |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 869 | * This function returns the stable tree node of identical content if found, |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 870 | * NULL otherwise. |
| 871 | */ |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 872 | static struct stable_node *stable_tree_search(struct page *page) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 873 | { |
| 874 | struct rb_node *node = root_stable_tree.rb_node; |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 875 | struct stable_node *stable_node; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 876 | |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 877 | stable_node = page_stable_node(page); |
| 878 | if (stable_node) { /* ksm page forked */ |
| 879 | get_page(page); |
| 880 | return stable_node; |
| 881 | } |
| 882 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 883 | while (node) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 884 | int ret; |
| 885 | |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 886 | cond_resched(); |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 887 | stable_node = rb_entry(node, struct stable_node, node); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 888 | |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 889 | ret = memcmp_pages(page, stable_node->page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 890 | |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 891 | if (ret < 0) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 892 | node = node->rb_left; |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 893 | else if (ret > 0) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 894 | node = node->rb_right; |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 895 | else { |
| 896 | get_page(stable_node->page); |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 897 | return stable_node; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 898 | } |
| 899 | } |
| 900 | |
| 901 | return NULL; |
| 902 | } |
| 903 | |
| 904 | /* |
| 905 | * stable_tree_insert - insert rmap_item pointing to new ksm page |
| 906 | * into the stable tree. |
| 907 | * |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 908 | * This function returns the stable tree node just allocated on success, |
| 909 | * NULL otherwise. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 910 | */ |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 911 | static struct stable_node *stable_tree_insert(struct page *kpage) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 912 | { |
| 913 | struct rb_node **new = &root_stable_tree.rb_node; |
| 914 | struct rb_node *parent = NULL; |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 915 | struct stable_node *stable_node; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 916 | |
| 917 | while (*new) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 918 | int ret; |
| 919 | |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 920 | cond_resched(); |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 921 | stable_node = rb_entry(*new, struct stable_node, node); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 922 | |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 923 | ret = memcmp_pages(kpage, stable_node->page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 924 | |
| 925 | parent = *new; |
| 926 | if (ret < 0) |
| 927 | new = &parent->rb_left; |
| 928 | else if (ret > 0) |
| 929 | new = &parent->rb_right; |
| 930 | else { |
| 931 | /* |
| 932 | * It is not a bug that stable_tree_search() didn't |
| 933 | * find this node: because at that time our page was |
| 934 | * not yet write-protected, so may have changed since. |
| 935 | */ |
| 936 | return NULL; |
| 937 | } |
| 938 | } |
| 939 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 940 | stable_node = alloc_stable_node(); |
| 941 | if (!stable_node) |
| 942 | return NULL; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 943 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 944 | rb_link_node(&stable_node->node, parent, new); |
| 945 | rb_insert_color(&stable_node->node, &root_stable_tree); |
| 946 | |
| 947 | INIT_HLIST_HEAD(&stable_node->hlist); |
| 948 | |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 949 | get_page(kpage); |
| 950 | stable_node->page = kpage; |
| 951 | set_page_stable_node(kpage, stable_node); |
| 952 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 953 | return stable_node; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 954 | } |
| 955 | |
| 956 | /* |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 957 | * unstable_tree_search_insert - search for identical page, |
| 958 | * else insert rmap_item into the unstable tree. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 959 | * |
| 960 | * This function searches for a page in the unstable tree identical to the |
| 961 | * page currently being scanned; and if no identical page is found in the |
| 962 | * tree, we insert rmap_item as a new object into the unstable tree. |
| 963 | * |
| 964 | * This function returns pointer to rmap_item found to be identical |
| 965 | * to the currently scanned page, NULL otherwise. |
| 966 | * |
| 967 | * This function does both searching and inserting, because they share |
| 968 | * the same walking algorithm in an rbtree. |
| 969 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 970 | static |
| 971 | struct rmap_item *unstable_tree_search_insert(struct rmap_item *rmap_item, |
| 972 | struct page *page, |
| 973 | struct page **tree_pagep) |
| 974 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 975 | { |
| 976 | struct rb_node **new = &root_unstable_tree.rb_node; |
| 977 | struct rb_node *parent = NULL; |
| 978 | |
| 979 | while (*new) { |
| 980 | struct rmap_item *tree_rmap_item; |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 981 | struct page *tree_page; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 982 | int ret; |
| 983 | |
Hugh Dickins | d178f27 | 2009-11-09 15:58:23 +0000 | [diff] [blame] | 984 | cond_resched(); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 985 | tree_rmap_item = rb_entry(*new, struct rmap_item, node); |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 986 | tree_page = get_mergeable_page(tree_rmap_item); |
| 987 | if (!tree_page) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 988 | return NULL; |
| 989 | |
| 990 | /* |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 991 | * Don't substitute a ksm page for a forked page. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 992 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 993 | if (page == tree_page) { |
| 994 | put_page(tree_page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 995 | return NULL; |
| 996 | } |
| 997 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 998 | ret = memcmp_pages(page, tree_page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 999 | |
| 1000 | parent = *new; |
| 1001 | if (ret < 0) { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1002 | put_page(tree_page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1003 | new = &parent->rb_left; |
| 1004 | } else if (ret > 0) { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1005 | put_page(tree_page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1006 | new = &parent->rb_right; |
| 1007 | } else { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1008 | *tree_pagep = tree_page; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1009 | return tree_rmap_item; |
| 1010 | } |
| 1011 | } |
| 1012 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1013 | rmap_item->address |= UNSTABLE_FLAG; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1014 | rmap_item->address |= (ksm_scan.seqnr & SEQNR_MASK); |
| 1015 | rb_link_node(&rmap_item->node, parent, new); |
| 1016 | rb_insert_color(&rmap_item->node, &root_unstable_tree); |
| 1017 | |
Hugh Dickins | 473b0ce | 2009-09-21 17:02:11 -0700 | [diff] [blame] | 1018 | ksm_pages_unshared++; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1019 | return NULL; |
| 1020 | } |
| 1021 | |
| 1022 | /* |
| 1023 | * stable_tree_append - add another rmap_item to the linked list of |
| 1024 | * rmap_items hanging off a given node of the stable tree, all sharing |
| 1025 | * the same ksm page. |
| 1026 | */ |
| 1027 | static void stable_tree_append(struct rmap_item *rmap_item, |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1028 | struct stable_node *stable_node) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1029 | { |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1030 | rmap_item->head = stable_node; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1031 | rmap_item->address |= STABLE_FLAG; |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1032 | hlist_add_head(&rmap_item->hlist, &stable_node->hlist); |
Hugh Dickins | e178dfd | 2009-09-21 17:02:10 -0700 | [diff] [blame] | 1033 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1034 | if (rmap_item->hlist.next) |
| 1035 | ksm_pages_sharing++; |
| 1036 | else |
| 1037 | ksm_pages_shared++; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1038 | } |
| 1039 | |
| 1040 | /* |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 1041 | * cmp_and_merge_page - first see if page can be merged into the stable tree; |
| 1042 | * if not, compare checksum to previous and if it's the same, see if page can |
| 1043 | * be inserted into the unstable tree, or merged with a page already there and |
| 1044 | * both transferred to the stable tree. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1045 | * |
| 1046 | * @page: the page that we are searching identical page to. |
| 1047 | * @rmap_item: the reverse mapping into the virtual address of this page |
| 1048 | */ |
| 1049 | static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item) |
| 1050 | { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1051 | struct rmap_item *tree_rmap_item; |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1052 | struct page *tree_page = NULL; |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1053 | struct stable_node *stable_node; |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1054 | struct page *kpage; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1055 | unsigned int checksum; |
| 1056 | int err; |
| 1057 | |
Hugh Dickins | 93d1771 | 2009-12-14 17:59:16 -0800 | [diff] [blame] | 1058 | remove_rmap_item_from_tree(rmap_item); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1059 | |
| 1060 | /* We first start with searching the page inside the stable tree */ |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 1061 | stable_node = stable_tree_search(page); |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1062 | if (stable_node) { |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 1063 | kpage = stable_node->page; |
| 1064 | err = try_to_merge_with_ksm_page(rmap_item, page, kpage); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1065 | if (!err) { |
| 1066 | /* |
| 1067 | * The page was successfully merged: |
| 1068 | * add its rmap_item to the stable tree. |
| 1069 | */ |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1070 | stable_tree_append(rmap_item, stable_node); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1071 | } |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1072 | put_page(kpage); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1073 | return; |
| 1074 | } |
| 1075 | |
| 1076 | /* |
| 1077 | * A ksm page might have got here by fork, but its other |
| 1078 | * references have already been removed from the stable tree. |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 1079 | * Or it might be left over from a break_ksm which failed |
| 1080 | * when the mem_cgroup had reached its limit: try again now. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1081 | */ |
| 1082 | if (PageKsm(page)) |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1083 | break_cow(rmap_item); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1084 | |
| 1085 | /* |
| 1086 | * In case the hash value of the page was changed from the last time we |
| 1087 | * have calculated it, this page to be changed frequely, therefore we |
| 1088 | * don't want to insert it to the unstable tree, and we don't want to |
| 1089 | * waste our time to search if there is something identical to it there. |
| 1090 | */ |
| 1091 | checksum = calc_checksum(page); |
| 1092 | if (rmap_item->oldchecksum != checksum) { |
| 1093 | rmap_item->oldchecksum = checksum; |
| 1094 | return; |
| 1095 | } |
| 1096 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1097 | tree_rmap_item = |
| 1098 | unstable_tree_search_insert(rmap_item, page, &tree_page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1099 | if (tree_rmap_item) { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1100 | kpage = try_to_merge_two_pages(rmap_item, page, |
| 1101 | tree_rmap_item, tree_page); |
| 1102 | put_page(tree_page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1103 | /* |
| 1104 | * As soon as we merge this page, we want to remove the |
| 1105 | * rmap_item of the page we have merged with from the unstable |
| 1106 | * tree, and insert it instead as new node in the stable tree. |
| 1107 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1108 | if (kpage) { |
Hugh Dickins | 93d1771 | 2009-12-14 17:59:16 -0800 | [diff] [blame] | 1109 | remove_rmap_item_from_tree(tree_rmap_item); |
Hugh Dickins | 473b0ce | 2009-09-21 17:02:11 -0700 | [diff] [blame] | 1110 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1111 | stable_node = stable_tree_insert(kpage); |
| 1112 | if (stable_node) { |
| 1113 | stable_tree_append(tree_rmap_item, stable_node); |
| 1114 | stable_tree_append(rmap_item, stable_node); |
| 1115 | } |
| 1116 | put_page(kpage); |
| 1117 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1118 | /* |
| 1119 | * If we fail to insert the page into the stable tree, |
| 1120 | * we will have 2 virtual addresses that are pointing |
| 1121 | * to a ksm page left outside the stable tree, |
| 1122 | * in which case we need to break_cow on both. |
| 1123 | */ |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1124 | if (!stable_node) { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1125 | break_cow(tree_rmap_item); |
| 1126 | break_cow(rmap_item); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1127 | } |
| 1128 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1129 | } |
| 1130 | } |
| 1131 | |
| 1132 | static struct rmap_item *get_next_rmap_item(struct mm_slot *mm_slot, |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1133 | struct rmap_item **rmap_list, |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1134 | unsigned long addr) |
| 1135 | { |
| 1136 | struct rmap_item *rmap_item; |
| 1137 | |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1138 | while (*rmap_list) { |
| 1139 | rmap_item = *rmap_list; |
Hugh Dickins | 93d1771 | 2009-12-14 17:59:16 -0800 | [diff] [blame] | 1140 | if ((rmap_item->address & PAGE_MASK) == addr) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1141 | return rmap_item; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1142 | if (rmap_item->address > addr) |
| 1143 | break; |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1144 | *rmap_list = rmap_item->rmap_list; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1145 | remove_rmap_item_from_tree(rmap_item); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1146 | free_rmap_item(rmap_item); |
| 1147 | } |
| 1148 | |
| 1149 | rmap_item = alloc_rmap_item(); |
| 1150 | if (rmap_item) { |
| 1151 | /* It has already been zeroed */ |
| 1152 | rmap_item->mm = mm_slot->mm; |
| 1153 | rmap_item->address = addr; |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1154 | rmap_item->rmap_list = *rmap_list; |
| 1155 | *rmap_list = rmap_item; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1156 | } |
| 1157 | return rmap_item; |
| 1158 | } |
| 1159 | |
| 1160 | static struct rmap_item *scan_get_next_rmap_item(struct page **page) |
| 1161 | { |
| 1162 | struct mm_struct *mm; |
| 1163 | struct mm_slot *slot; |
| 1164 | struct vm_area_struct *vma; |
| 1165 | struct rmap_item *rmap_item; |
| 1166 | |
| 1167 | if (list_empty(&ksm_mm_head.mm_list)) |
| 1168 | return NULL; |
| 1169 | |
| 1170 | slot = ksm_scan.mm_slot; |
| 1171 | if (slot == &ksm_mm_head) { |
| 1172 | root_unstable_tree = RB_ROOT; |
| 1173 | |
| 1174 | spin_lock(&ksm_mmlist_lock); |
| 1175 | slot = list_entry(slot->mm_list.next, struct mm_slot, mm_list); |
| 1176 | ksm_scan.mm_slot = slot; |
| 1177 | spin_unlock(&ksm_mmlist_lock); |
| 1178 | next_mm: |
| 1179 | ksm_scan.address = 0; |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1180 | ksm_scan.rmap_list = &slot->rmap_list; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1181 | } |
| 1182 | |
| 1183 | mm = slot->mm; |
| 1184 | down_read(&mm->mmap_sem); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1185 | if (ksm_test_exit(mm)) |
| 1186 | vma = NULL; |
| 1187 | else |
| 1188 | vma = find_vma(mm, ksm_scan.address); |
| 1189 | |
| 1190 | for (; vma; vma = vma->vm_next) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1191 | if (!(vma->vm_flags & VM_MERGEABLE)) |
| 1192 | continue; |
| 1193 | if (ksm_scan.address < vma->vm_start) |
| 1194 | ksm_scan.address = vma->vm_start; |
| 1195 | if (!vma->anon_vma) |
| 1196 | ksm_scan.address = vma->vm_end; |
| 1197 | |
| 1198 | while (ksm_scan.address < vma->vm_end) { |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1199 | if (ksm_test_exit(mm)) |
| 1200 | break; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1201 | *page = follow_page(vma, ksm_scan.address, FOLL_GET); |
| 1202 | if (*page && PageAnon(*page)) { |
| 1203 | flush_anon_page(vma, *page, ksm_scan.address); |
| 1204 | flush_dcache_page(*page); |
| 1205 | rmap_item = get_next_rmap_item(slot, |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1206 | ksm_scan.rmap_list, ksm_scan.address); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1207 | if (rmap_item) { |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1208 | ksm_scan.rmap_list = |
| 1209 | &rmap_item->rmap_list; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1210 | ksm_scan.address += PAGE_SIZE; |
| 1211 | } else |
| 1212 | put_page(*page); |
| 1213 | up_read(&mm->mmap_sem); |
| 1214 | return rmap_item; |
| 1215 | } |
| 1216 | if (*page) |
| 1217 | put_page(*page); |
| 1218 | ksm_scan.address += PAGE_SIZE; |
| 1219 | cond_resched(); |
| 1220 | } |
| 1221 | } |
| 1222 | |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1223 | if (ksm_test_exit(mm)) { |
| 1224 | ksm_scan.address = 0; |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1225 | ksm_scan.rmap_list = &slot->rmap_list; |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1226 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1227 | /* |
| 1228 | * Nuke all the rmap_items that are above this current rmap: |
| 1229 | * because there were no VM_MERGEABLE vmas with such addresses. |
| 1230 | */ |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1231 | remove_trailing_rmap_items(slot, ksm_scan.rmap_list); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1232 | |
| 1233 | spin_lock(&ksm_mmlist_lock); |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1234 | ksm_scan.mm_slot = list_entry(slot->mm_list.next, |
| 1235 | struct mm_slot, mm_list); |
| 1236 | if (ksm_scan.address == 0) { |
| 1237 | /* |
| 1238 | * We've completed a full scan of all vmas, holding mmap_sem |
| 1239 | * throughout, and found no VM_MERGEABLE: so do the same as |
| 1240 | * __ksm_exit does to remove this mm from all our lists now. |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1241 | * This applies either when cleaning up after __ksm_exit |
| 1242 | * (but beware: we can reach here even before __ksm_exit), |
| 1243 | * or when all VM_MERGEABLE areas have been unmapped (and |
| 1244 | * mmap_sem then protects against race with MADV_MERGEABLE). |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1245 | */ |
| 1246 | hlist_del(&slot->link); |
| 1247 | list_del(&slot->mm_list); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1248 | spin_unlock(&ksm_mmlist_lock); |
| 1249 | |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1250 | free_mm_slot(slot); |
| 1251 | clear_bit(MMF_VM_MERGEABLE, &mm->flags); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1252 | up_read(&mm->mmap_sem); |
| 1253 | mmdrop(mm); |
| 1254 | } else { |
| 1255 | spin_unlock(&ksm_mmlist_lock); |
| 1256 | up_read(&mm->mmap_sem); |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1257 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1258 | |
| 1259 | /* Repeat until we've completed scanning the whole list */ |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1260 | slot = ksm_scan.mm_slot; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1261 | if (slot != &ksm_mm_head) |
| 1262 | goto next_mm; |
| 1263 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1264 | ksm_scan.seqnr++; |
| 1265 | return NULL; |
| 1266 | } |
| 1267 | |
| 1268 | /** |
| 1269 | * ksm_do_scan - the ksm scanner main worker function. |
| 1270 | * @scan_npages - number of pages we want to scan before we return. |
| 1271 | */ |
| 1272 | static void ksm_do_scan(unsigned int scan_npages) |
| 1273 | { |
| 1274 | struct rmap_item *rmap_item; |
| 1275 | struct page *page; |
| 1276 | |
| 1277 | while (scan_npages--) { |
| 1278 | cond_resched(); |
| 1279 | rmap_item = scan_get_next_rmap_item(&page); |
| 1280 | if (!rmap_item) |
| 1281 | return; |
| 1282 | if (!PageKsm(page) || !in_stable_tree(rmap_item)) |
| 1283 | cmp_and_merge_page(page, rmap_item); |
Hugh Dickins | 26465d3 | 2009-09-21 17:02:12 -0700 | [diff] [blame] | 1284 | else if (page_mapcount(page) == 1) { |
| 1285 | /* |
| 1286 | * Replace now-unshared ksm page by ordinary page. |
| 1287 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1288 | break_cow(rmap_item); |
Hugh Dickins | 26465d3 | 2009-09-21 17:02:12 -0700 | [diff] [blame] | 1289 | remove_rmap_item_from_tree(rmap_item); |
| 1290 | rmap_item->oldchecksum = calc_checksum(page); |
| 1291 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1292 | put_page(page); |
| 1293 | } |
| 1294 | } |
| 1295 | |
Hugh Dickins | 6e15838 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1296 | static int ksmd_should_run(void) |
| 1297 | { |
| 1298 | return (ksm_run & KSM_RUN_MERGE) && !list_empty(&ksm_mm_head.mm_list); |
| 1299 | } |
| 1300 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1301 | static int ksm_scan_thread(void *nothing) |
| 1302 | { |
Izik Eidus | 339aa62 | 2009-09-21 17:02:07 -0700 | [diff] [blame] | 1303 | set_user_nice(current, 5); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1304 | |
| 1305 | while (!kthread_should_stop()) { |
Hugh Dickins | 6e15838 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1306 | mutex_lock(&ksm_thread_mutex); |
| 1307 | if (ksmd_should_run()) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1308 | ksm_do_scan(ksm_thread_pages_to_scan); |
Hugh Dickins | 6e15838 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1309 | mutex_unlock(&ksm_thread_mutex); |
| 1310 | |
| 1311 | if (ksmd_should_run()) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1312 | schedule_timeout_interruptible( |
| 1313 | msecs_to_jiffies(ksm_thread_sleep_millisecs)); |
| 1314 | } else { |
| 1315 | wait_event_interruptible(ksm_thread_wait, |
Hugh Dickins | 6e15838 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1316 | ksmd_should_run() || kthread_should_stop()); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1317 | } |
| 1318 | } |
| 1319 | return 0; |
| 1320 | } |
| 1321 | |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1322 | int ksm_madvise(struct vm_area_struct *vma, unsigned long start, |
| 1323 | unsigned long end, int advice, unsigned long *vm_flags) |
| 1324 | { |
| 1325 | struct mm_struct *mm = vma->vm_mm; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 1326 | int err; |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1327 | |
| 1328 | switch (advice) { |
| 1329 | case MADV_MERGEABLE: |
| 1330 | /* |
| 1331 | * Be somewhat over-protective for now! |
| 1332 | */ |
| 1333 | if (*vm_flags & (VM_MERGEABLE | VM_SHARED | VM_MAYSHARE | |
| 1334 | VM_PFNMAP | VM_IO | VM_DONTEXPAND | |
| 1335 | VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE | |
| 1336 | VM_MIXEDMAP | VM_SAO)) |
| 1337 | return 0; /* just ignore the advice */ |
| 1338 | |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 1339 | if (!test_bit(MMF_VM_MERGEABLE, &mm->flags)) { |
| 1340 | err = __ksm_enter(mm); |
| 1341 | if (err) |
| 1342 | return err; |
| 1343 | } |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1344 | |
| 1345 | *vm_flags |= VM_MERGEABLE; |
| 1346 | break; |
| 1347 | |
| 1348 | case MADV_UNMERGEABLE: |
| 1349 | if (!(*vm_flags & VM_MERGEABLE)) |
| 1350 | return 0; /* just ignore the advice */ |
| 1351 | |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 1352 | if (vma->anon_vma) { |
| 1353 | err = unmerge_ksm_pages(vma, start, end); |
| 1354 | if (err) |
| 1355 | return err; |
| 1356 | } |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1357 | |
| 1358 | *vm_flags &= ~VM_MERGEABLE; |
| 1359 | break; |
| 1360 | } |
| 1361 | |
| 1362 | return 0; |
| 1363 | } |
| 1364 | |
| 1365 | int __ksm_enter(struct mm_struct *mm) |
| 1366 | { |
Hugh Dickins | 6e15838 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1367 | struct mm_slot *mm_slot; |
| 1368 | int needs_wakeup; |
| 1369 | |
| 1370 | mm_slot = alloc_mm_slot(); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1371 | if (!mm_slot) |
| 1372 | return -ENOMEM; |
| 1373 | |
Hugh Dickins | 6e15838 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1374 | /* Check ksm_run too? Would need tighter locking */ |
| 1375 | needs_wakeup = list_empty(&ksm_mm_head.mm_list); |
| 1376 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1377 | spin_lock(&ksm_mmlist_lock); |
| 1378 | insert_to_mm_slots_hash(mm, mm_slot); |
| 1379 | /* |
| 1380 | * Insert just behind the scanning cursor, to let the area settle |
| 1381 | * down a little; when fork is followed by immediate exec, we don't |
| 1382 | * want ksmd to waste time setting up and tearing down an rmap_list. |
| 1383 | */ |
| 1384 | list_add_tail(&mm_slot->mm_list, &ksm_scan.mm_slot->mm_list); |
| 1385 | spin_unlock(&ksm_mmlist_lock); |
| 1386 | |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1387 | set_bit(MMF_VM_MERGEABLE, &mm->flags); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1388 | atomic_inc(&mm->mm_count); |
Hugh Dickins | 6e15838 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1389 | |
| 1390 | if (needs_wakeup) |
| 1391 | wake_up_interruptible(&ksm_thread_wait); |
| 1392 | |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1393 | return 0; |
| 1394 | } |
| 1395 | |
Andrea Arcangeli | 1c2fb7a | 2009-09-21 17:02:22 -0700 | [diff] [blame] | 1396 | void __ksm_exit(struct mm_struct *mm) |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1397 | { |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1398 | struct mm_slot *mm_slot; |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1399 | int easy_to_free = 0; |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1400 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1401 | /* |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1402 | * This process is exiting: if it's straightforward (as is the |
| 1403 | * case when ksmd was never running), free mm_slot immediately. |
| 1404 | * But if it's at the cursor or has rmap_items linked to it, use |
| 1405 | * mmap_sem to synchronize with any break_cows before pagetables |
| 1406 | * are freed, and leave the mm_slot on the list for ksmd to free. |
| 1407 | * Beware: ksm may already have noticed it exiting and freed the slot. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1408 | */ |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1409 | |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1410 | spin_lock(&ksm_mmlist_lock); |
| 1411 | mm_slot = get_mm_slot(mm); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1412 | if (mm_slot && ksm_scan.mm_slot != mm_slot) { |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1413 | if (!mm_slot->rmap_list) { |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1414 | hlist_del(&mm_slot->link); |
| 1415 | list_del(&mm_slot->mm_list); |
| 1416 | easy_to_free = 1; |
| 1417 | } else { |
| 1418 | list_move(&mm_slot->mm_list, |
| 1419 | &ksm_scan.mm_slot->mm_list); |
| 1420 | } |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1421 | } |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1422 | spin_unlock(&ksm_mmlist_lock); |
| 1423 | |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1424 | if (easy_to_free) { |
| 1425 | free_mm_slot(mm_slot); |
| 1426 | clear_bit(MMF_VM_MERGEABLE, &mm->flags); |
| 1427 | mmdrop(mm); |
| 1428 | } else if (mm_slot) { |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1429 | down_write(&mm->mmap_sem); |
| 1430 | up_write(&mm->mmap_sem); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1431 | } |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1432 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1433 | |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 1434 | #ifdef CONFIG_SYSFS |
| 1435 | /* |
| 1436 | * This all compiles without CONFIG_SYSFS, but is a waste of space. |
| 1437 | */ |
| 1438 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1439 | #define KSM_ATTR_RO(_name) \ |
| 1440 | static struct kobj_attribute _name##_attr = __ATTR_RO(_name) |
| 1441 | #define KSM_ATTR(_name) \ |
| 1442 | static struct kobj_attribute _name##_attr = \ |
| 1443 | __ATTR(_name, 0644, _name##_show, _name##_store) |
| 1444 | |
| 1445 | static ssize_t sleep_millisecs_show(struct kobject *kobj, |
| 1446 | struct kobj_attribute *attr, char *buf) |
| 1447 | { |
| 1448 | return sprintf(buf, "%u\n", ksm_thread_sleep_millisecs); |
| 1449 | } |
| 1450 | |
| 1451 | static ssize_t sleep_millisecs_store(struct kobject *kobj, |
| 1452 | struct kobj_attribute *attr, |
| 1453 | const char *buf, size_t count) |
| 1454 | { |
| 1455 | unsigned long msecs; |
| 1456 | int err; |
| 1457 | |
| 1458 | err = strict_strtoul(buf, 10, &msecs); |
| 1459 | if (err || msecs > UINT_MAX) |
| 1460 | return -EINVAL; |
| 1461 | |
| 1462 | ksm_thread_sleep_millisecs = msecs; |
| 1463 | |
| 1464 | return count; |
| 1465 | } |
| 1466 | KSM_ATTR(sleep_millisecs); |
| 1467 | |
| 1468 | static ssize_t pages_to_scan_show(struct kobject *kobj, |
| 1469 | struct kobj_attribute *attr, char *buf) |
| 1470 | { |
| 1471 | return sprintf(buf, "%u\n", ksm_thread_pages_to_scan); |
| 1472 | } |
| 1473 | |
| 1474 | static ssize_t pages_to_scan_store(struct kobject *kobj, |
| 1475 | struct kobj_attribute *attr, |
| 1476 | const char *buf, size_t count) |
| 1477 | { |
| 1478 | int err; |
| 1479 | unsigned long nr_pages; |
| 1480 | |
| 1481 | err = strict_strtoul(buf, 10, &nr_pages); |
| 1482 | if (err || nr_pages > UINT_MAX) |
| 1483 | return -EINVAL; |
| 1484 | |
| 1485 | ksm_thread_pages_to_scan = nr_pages; |
| 1486 | |
| 1487 | return count; |
| 1488 | } |
| 1489 | KSM_ATTR(pages_to_scan); |
| 1490 | |
| 1491 | static ssize_t run_show(struct kobject *kobj, struct kobj_attribute *attr, |
| 1492 | char *buf) |
| 1493 | { |
| 1494 | return sprintf(buf, "%u\n", ksm_run); |
| 1495 | } |
| 1496 | |
| 1497 | static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr, |
| 1498 | const char *buf, size_t count) |
| 1499 | { |
| 1500 | int err; |
| 1501 | unsigned long flags; |
| 1502 | |
| 1503 | err = strict_strtoul(buf, 10, &flags); |
| 1504 | if (err || flags > UINT_MAX) |
| 1505 | return -EINVAL; |
| 1506 | if (flags > KSM_RUN_UNMERGE) |
| 1507 | return -EINVAL; |
| 1508 | |
| 1509 | /* |
| 1510 | * KSM_RUN_MERGE sets ksmd running, and 0 stops it running. |
| 1511 | * KSM_RUN_UNMERGE stops it running and unmerges all rmap_items, |
Hugh Dickins | b402826 | 2009-09-21 17:02:09 -0700 | [diff] [blame] | 1512 | * breaking COW to free the unswappable pages_shared (but leaves |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1513 | * mm_slots on the list for when ksmd may be set running again). |
| 1514 | */ |
| 1515 | |
| 1516 | mutex_lock(&ksm_thread_mutex); |
| 1517 | if (ksm_run != flags) { |
| 1518 | ksm_run = flags; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 1519 | if (flags & KSM_RUN_UNMERGE) { |
Hugh Dickins | 35451be | 2009-09-21 17:02:27 -0700 | [diff] [blame] | 1520 | current->flags |= PF_OOM_ORIGIN; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 1521 | err = unmerge_and_remove_all_rmap_items(); |
Hugh Dickins | 35451be | 2009-09-21 17:02:27 -0700 | [diff] [blame] | 1522 | current->flags &= ~PF_OOM_ORIGIN; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 1523 | if (err) { |
| 1524 | ksm_run = KSM_RUN_STOP; |
| 1525 | count = err; |
| 1526 | } |
| 1527 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1528 | } |
| 1529 | mutex_unlock(&ksm_thread_mutex); |
| 1530 | |
| 1531 | if (flags & KSM_RUN_MERGE) |
| 1532 | wake_up_interruptible(&ksm_thread_wait); |
| 1533 | |
| 1534 | return count; |
| 1535 | } |
| 1536 | KSM_ATTR(run); |
| 1537 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1538 | static ssize_t max_kernel_pages_store(struct kobject *kobj, |
| 1539 | struct kobj_attribute *attr, |
| 1540 | const char *buf, size_t count) |
| 1541 | { |
| 1542 | int err; |
| 1543 | unsigned long nr_pages; |
| 1544 | |
| 1545 | err = strict_strtoul(buf, 10, &nr_pages); |
| 1546 | if (err) |
| 1547 | return -EINVAL; |
| 1548 | |
| 1549 | ksm_max_kernel_pages = nr_pages; |
| 1550 | |
| 1551 | return count; |
| 1552 | } |
| 1553 | |
| 1554 | static ssize_t max_kernel_pages_show(struct kobject *kobj, |
| 1555 | struct kobj_attribute *attr, char *buf) |
| 1556 | { |
| 1557 | return sprintf(buf, "%lu\n", ksm_max_kernel_pages); |
| 1558 | } |
| 1559 | KSM_ATTR(max_kernel_pages); |
| 1560 | |
Hugh Dickins | b402826 | 2009-09-21 17:02:09 -0700 | [diff] [blame] | 1561 | static ssize_t pages_shared_show(struct kobject *kobj, |
| 1562 | struct kobj_attribute *attr, char *buf) |
| 1563 | { |
| 1564 | return sprintf(buf, "%lu\n", ksm_pages_shared); |
| 1565 | } |
| 1566 | KSM_ATTR_RO(pages_shared); |
| 1567 | |
| 1568 | static ssize_t pages_sharing_show(struct kobject *kobj, |
| 1569 | struct kobj_attribute *attr, char *buf) |
| 1570 | { |
Hugh Dickins | e178dfd | 2009-09-21 17:02:10 -0700 | [diff] [blame] | 1571 | return sprintf(buf, "%lu\n", ksm_pages_sharing); |
Hugh Dickins | b402826 | 2009-09-21 17:02:09 -0700 | [diff] [blame] | 1572 | } |
| 1573 | KSM_ATTR_RO(pages_sharing); |
| 1574 | |
Hugh Dickins | 473b0ce | 2009-09-21 17:02:11 -0700 | [diff] [blame] | 1575 | static ssize_t pages_unshared_show(struct kobject *kobj, |
| 1576 | struct kobj_attribute *attr, char *buf) |
| 1577 | { |
| 1578 | return sprintf(buf, "%lu\n", ksm_pages_unshared); |
| 1579 | } |
| 1580 | KSM_ATTR_RO(pages_unshared); |
| 1581 | |
| 1582 | static ssize_t pages_volatile_show(struct kobject *kobj, |
| 1583 | struct kobj_attribute *attr, char *buf) |
| 1584 | { |
| 1585 | long ksm_pages_volatile; |
| 1586 | |
| 1587 | ksm_pages_volatile = ksm_rmap_items - ksm_pages_shared |
| 1588 | - ksm_pages_sharing - ksm_pages_unshared; |
| 1589 | /* |
| 1590 | * It was not worth any locking to calculate that statistic, |
| 1591 | * but it might therefore sometimes be negative: conceal that. |
| 1592 | */ |
| 1593 | if (ksm_pages_volatile < 0) |
| 1594 | ksm_pages_volatile = 0; |
| 1595 | return sprintf(buf, "%ld\n", ksm_pages_volatile); |
| 1596 | } |
| 1597 | KSM_ATTR_RO(pages_volatile); |
| 1598 | |
| 1599 | static ssize_t full_scans_show(struct kobject *kobj, |
| 1600 | struct kobj_attribute *attr, char *buf) |
| 1601 | { |
| 1602 | return sprintf(buf, "%lu\n", ksm_scan.seqnr); |
| 1603 | } |
| 1604 | KSM_ATTR_RO(full_scans); |
| 1605 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1606 | static struct attribute *ksm_attrs[] = { |
| 1607 | &sleep_millisecs_attr.attr, |
| 1608 | &pages_to_scan_attr.attr, |
| 1609 | &run_attr.attr, |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1610 | &max_kernel_pages_attr.attr, |
Hugh Dickins | b402826 | 2009-09-21 17:02:09 -0700 | [diff] [blame] | 1611 | &pages_shared_attr.attr, |
| 1612 | &pages_sharing_attr.attr, |
Hugh Dickins | 473b0ce | 2009-09-21 17:02:11 -0700 | [diff] [blame] | 1613 | &pages_unshared_attr.attr, |
| 1614 | &pages_volatile_attr.attr, |
| 1615 | &full_scans_attr.attr, |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1616 | NULL, |
| 1617 | }; |
| 1618 | |
| 1619 | static struct attribute_group ksm_attr_group = { |
| 1620 | .attrs = ksm_attrs, |
| 1621 | .name = "ksm", |
| 1622 | }; |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 1623 | #endif /* CONFIG_SYSFS */ |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1624 | |
| 1625 | static int __init ksm_init(void) |
| 1626 | { |
| 1627 | struct task_struct *ksm_thread; |
| 1628 | int err; |
| 1629 | |
Hugh Dickins | c73602a | 2009-10-07 16:32:22 -0700 | [diff] [blame] | 1630 | ksm_max_kernel_pages = totalram_pages / 4; |
Izik Eidus | 2c6854f | 2009-09-23 15:56:04 -0700 | [diff] [blame] | 1631 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1632 | err = ksm_slab_init(); |
| 1633 | if (err) |
| 1634 | goto out; |
| 1635 | |
| 1636 | err = mm_slots_hash_init(); |
| 1637 | if (err) |
| 1638 | goto out_free1; |
| 1639 | |
| 1640 | ksm_thread = kthread_run(ksm_scan_thread, NULL, "ksmd"); |
| 1641 | if (IS_ERR(ksm_thread)) { |
| 1642 | printk(KERN_ERR "ksm: creating kthread failed\n"); |
| 1643 | err = PTR_ERR(ksm_thread); |
| 1644 | goto out_free2; |
| 1645 | } |
| 1646 | |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 1647 | #ifdef CONFIG_SYSFS |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1648 | err = sysfs_create_group(mm_kobj, &ksm_attr_group); |
| 1649 | if (err) { |
| 1650 | printk(KERN_ERR "ksm: register sysfs failed\n"); |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 1651 | kthread_stop(ksm_thread); |
| 1652 | goto out_free2; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1653 | } |
Hugh Dickins | c73602a | 2009-10-07 16:32:22 -0700 | [diff] [blame] | 1654 | #else |
| 1655 | ksm_run = KSM_RUN_MERGE; /* no way for user to start it */ |
| 1656 | |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 1657 | #endif /* CONFIG_SYSFS */ |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1658 | |
| 1659 | return 0; |
| 1660 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1661 | out_free2: |
| 1662 | mm_slots_hash_free(); |
| 1663 | out_free1: |
| 1664 | ksm_slab_free(); |
| 1665 | out: |
| 1666 | return err; |
| 1667 | } |
| 1668 | module_init(ksm_init) |