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> |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 32 | #include <linux/memory.h> |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 33 | #include <linux/mmu_notifier.h> |
Izik Eidus | 2c6854f | 2009-09-23 15:56:04 -0700 | [diff] [blame] | 34 | #include <linux/swap.h> |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 35 | #include <linux/ksm.h> |
Sasha Levin | 4ca3a69 | 2013-02-22 16:32:28 -0800 | [diff] [blame] | 36 | #include <linux/hashtable.h> |
Andrea Arcangeli | 878aee7 | 2011-01-13 15:47:10 -0800 | [diff] [blame] | 37 | #include <linux/freezer.h> |
David Rientjes | 72788c3 | 2011-05-24 17:11:40 -0700 | [diff] [blame] | 38 | #include <linux/oom.h> |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 39 | #include <linux/numa.h> |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 40 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 41 | #include <asm/tlbflush.h> |
Hugh Dickins | 73848b4 | 2009-12-14 17:59:22 -0800 | [diff] [blame] | 42 | #include "internal.h" |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 43 | |
Hugh Dickins | e850dcf | 2013-02-22 16:35:03 -0800 | [diff] [blame] | 44 | #ifdef CONFIG_NUMA |
| 45 | #define NUMA(x) (x) |
| 46 | #define DO_NUMA(x) do { (x); } while (0) |
| 47 | #else |
| 48 | #define NUMA(x) (0) |
| 49 | #define DO_NUMA(x) do { } while (0) |
| 50 | #endif |
| 51 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 52 | /* |
| 53 | * A few notes about the KSM scanning process, |
| 54 | * to make it easier to understand the data structures below: |
| 55 | * |
| 56 | * In order to reduce excessive scanning, KSM sorts the memory pages by their |
| 57 | * contents into a data structure that holds pointers to the pages' locations. |
| 58 | * |
| 59 | * Since the contents of the pages may change at any moment, KSM cannot just |
| 60 | * insert the pages into a normal sorted tree and expect it to find anything. |
| 61 | * Therefore KSM uses two data structures - the stable and the unstable tree. |
| 62 | * |
| 63 | * The stable tree holds pointers to all the merged pages (ksm pages), sorted |
| 64 | * by their contents. Because each such page is write-protected, searching on |
| 65 | * this tree is fully assured to be working (except when pages are unmapped), |
| 66 | * and therefore this tree is called the stable tree. |
| 67 | * |
| 68 | * In addition to the stable tree, KSM uses a second data structure called the |
| 69 | * unstable tree: this tree holds pointers to pages which have been found to |
| 70 | * be "unchanged for a period of time". The unstable tree sorts these pages |
| 71 | * by their contents, but since they are not write-protected, KSM cannot rely |
| 72 | * upon the unstable tree to work correctly - the unstable tree is liable to |
| 73 | * be corrupted as its contents are modified, and so it is called unstable. |
| 74 | * |
| 75 | * KSM solves this problem by several techniques: |
| 76 | * |
| 77 | * 1) The unstable tree is flushed every time KSM completes scanning all |
| 78 | * memory areas, and then the tree is rebuilt again from the beginning. |
| 79 | * 2) KSM will only insert into the unstable tree, pages whose hash value |
| 80 | * has not changed since the previous scan of all memory areas. |
| 81 | * 3) The unstable tree is a RedBlack Tree - so its balancing is based on the |
| 82 | * colors of the nodes and not on their contents, assuring that even when |
| 83 | * the tree gets "corrupted" it won't get out of balance, so scanning time |
| 84 | * remains the same (also, searching and inserting nodes in an rbtree uses |
| 85 | * the same algorithm, so we have no overhead when we flush and rebuild). |
| 86 | * 4) KSM never flushes the stable tree, which means that even if it were to |
| 87 | * take 10 attempts to find a page in the unstable tree, once it is found, |
| 88 | * it is secured in the stable tree. (When we scan a new page, we first |
| 89 | * compare it against the stable tree, and then against the unstable tree.) |
| 90 | */ |
| 91 | |
| 92 | /** |
| 93 | * struct mm_slot - ksm information per mm that is being scanned |
| 94 | * @link: link to the mm_slots hash list |
| 95 | * @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] | 96 | * @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] | 97 | * @mm: the mm that this information is valid for |
| 98 | */ |
| 99 | struct mm_slot { |
| 100 | struct hlist_node link; |
| 101 | struct list_head mm_list; |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 102 | struct rmap_item *rmap_list; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 103 | struct mm_struct *mm; |
| 104 | }; |
| 105 | |
| 106 | /** |
| 107 | * struct ksm_scan - cursor for scanning |
| 108 | * @mm_slot: the current mm_slot we are scanning |
| 109 | * @address: the next address inside that to be scanned |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 110 | * @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] | 111 | * @seqnr: count of completed full scans (needed when removing unstable node) |
| 112 | * |
| 113 | * There is only the one ksm_scan instance of this cursor structure. |
| 114 | */ |
| 115 | struct ksm_scan { |
| 116 | struct mm_slot *mm_slot; |
| 117 | unsigned long address; |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 118 | struct rmap_item **rmap_list; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 119 | unsigned long seqnr; |
| 120 | }; |
| 121 | |
| 122 | /** |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 123 | * struct stable_node - node of the stable rbtree |
| 124 | * @node: rb node of this ksm page in the stable tree |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 125 | * @head: (overlaying parent) &migrate_nodes indicates temporarily on that list |
| 126 | * @list: linked into migrate_nodes, pending placement in the proper node tree |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 127 | * @hlist: hlist head of rmap_items using this ksm page |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 128 | * @kpfn: page frame number of this ksm page (perhaps temporarily on wrong nid) |
| 129 | * @nid: NUMA node id of stable tree in which linked (may not match kpfn) |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 130 | */ |
| 131 | struct stable_node { |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 132 | union { |
| 133 | struct rb_node node; /* when node of stable tree */ |
| 134 | struct { /* when listed for migration */ |
| 135 | struct list_head *head; |
| 136 | struct list_head list; |
| 137 | }; |
| 138 | }; |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 139 | struct hlist_head hlist; |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 140 | unsigned long kpfn; |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 141 | #ifdef CONFIG_NUMA |
| 142 | int nid; |
| 143 | #endif |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 144 | }; |
| 145 | |
| 146 | /** |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 147 | * struct rmap_item - reverse mapping item for virtual addresses |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 148 | * @rmap_list: next rmap_item in mm_slot's singly-linked rmap_list |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 149 | * @anon_vma: pointer to anon_vma for this mm,address, when in stable tree |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 150 | * @mm: the memory structure this rmap_item is pointing into |
| 151 | * @address: the virtual address this rmap_item tracks (+ flags in low bits) |
| 152 | * @oldchecksum: previous checksum of the page at that virtual address |
Hugh Dickins | e850dcf | 2013-02-22 16:35:03 -0800 | [diff] [blame] | 153 | * @nid: NUMA node id of unstable tree in which linked (may not match page) |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 154 | * @node: rb node of this rmap_item in the unstable tree |
| 155 | * @head: pointer to stable_node heading this list in the stable tree |
| 156 | * @hlist: link into hlist of rmap_items hanging off that stable_node |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 157 | */ |
| 158 | struct rmap_item { |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 159 | struct rmap_item *rmap_list; |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 160 | struct anon_vma *anon_vma; /* when stable */ |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 161 | struct mm_struct *mm; |
| 162 | unsigned long address; /* + low bits used for flags below */ |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 163 | unsigned int oldchecksum; /* when unstable */ |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 164 | #ifdef CONFIG_NUMA |
Hugh Dickins | e850dcf | 2013-02-22 16:35:03 -0800 | [diff] [blame] | 165 | int nid; |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 166 | #endif |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 167 | union { |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 168 | struct rb_node node; /* when node of unstable tree */ |
| 169 | struct { /* when listed from stable tree */ |
| 170 | struct stable_node *head; |
| 171 | struct hlist_node hlist; |
| 172 | }; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 173 | }; |
| 174 | }; |
| 175 | |
| 176 | #define SEQNR_MASK 0x0ff /* low bits of unstable tree seqnr */ |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 177 | #define UNSTABLE_FLAG 0x100 /* is a node of the unstable tree */ |
| 178 | #define STABLE_FLAG 0x200 /* is listed from the stable tree */ |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 179 | |
| 180 | /* The stable and unstable tree heads */ |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 181 | static struct rb_root root_unstable_tree[MAX_NUMNODES]; |
| 182 | static struct rb_root root_stable_tree[MAX_NUMNODES]; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 183 | |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 184 | /* Recently migrated nodes of stable tree, pending proper placement */ |
| 185 | static LIST_HEAD(migrate_nodes); |
| 186 | |
Sasha Levin | 4ca3a69 | 2013-02-22 16:32:28 -0800 | [diff] [blame] | 187 | #define MM_SLOTS_HASH_BITS 10 |
| 188 | static DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 189 | |
| 190 | static struct mm_slot ksm_mm_head = { |
| 191 | .mm_list = LIST_HEAD_INIT(ksm_mm_head.mm_list), |
| 192 | }; |
| 193 | static struct ksm_scan ksm_scan = { |
| 194 | .mm_slot = &ksm_mm_head, |
| 195 | }; |
| 196 | |
| 197 | static struct kmem_cache *rmap_item_cache; |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 198 | static struct kmem_cache *stable_node_cache; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 199 | static struct kmem_cache *mm_slot_cache; |
| 200 | |
| 201 | /* The number of nodes in the stable tree */ |
Hugh Dickins | b402826 | 2009-09-21 17:02:09 -0700 | [diff] [blame] | 202 | static unsigned long ksm_pages_shared; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 203 | |
Hugh Dickins | e178dfd | 2009-09-21 17:02:10 -0700 | [diff] [blame] | 204 | /* The number of page slots additionally sharing those nodes */ |
Hugh Dickins | b402826 | 2009-09-21 17:02:09 -0700 | [diff] [blame] | 205 | static unsigned long ksm_pages_sharing; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 206 | |
Hugh Dickins | 473b0ce | 2009-09-21 17:02:11 -0700 | [diff] [blame] | 207 | /* The number of nodes in the unstable tree */ |
| 208 | static unsigned long ksm_pages_unshared; |
| 209 | |
| 210 | /* The number of rmap_items in use: to calculate pages_volatile */ |
| 211 | static unsigned long ksm_rmap_items; |
| 212 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 213 | /* Number of pages ksmd should scan in one batch */ |
Izik Eidus | 2c6854f | 2009-09-23 15:56:04 -0700 | [diff] [blame] | 214 | static unsigned int ksm_thread_pages_to_scan = 100; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 215 | |
| 216 | /* Milliseconds ksmd should sleep between batches */ |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 217 | static unsigned int ksm_thread_sleep_millisecs = 20; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 218 | |
Hugh Dickins | e850dcf | 2013-02-22 16:35:03 -0800 | [diff] [blame] | 219 | #ifdef CONFIG_NUMA |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 220 | /* Zeroed when merging across nodes is not allowed */ |
| 221 | static unsigned int ksm_merge_across_nodes = 1; |
Hugh Dickins | e850dcf | 2013-02-22 16:35:03 -0800 | [diff] [blame] | 222 | #else |
| 223 | #define ksm_merge_across_nodes 1U |
| 224 | #endif |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 225 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 226 | #define KSM_RUN_STOP 0 |
| 227 | #define KSM_RUN_MERGE 1 |
| 228 | #define KSM_RUN_UNMERGE 2 |
Izik Eidus | 2c6854f | 2009-09-23 15:56:04 -0700 | [diff] [blame] | 229 | static unsigned int ksm_run = KSM_RUN_STOP; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 230 | |
| 231 | static DECLARE_WAIT_QUEUE_HEAD(ksm_thread_wait); |
| 232 | static DEFINE_MUTEX(ksm_thread_mutex); |
| 233 | static DEFINE_SPINLOCK(ksm_mmlist_lock); |
| 234 | |
| 235 | #define KSM_KMEM_CACHE(__struct, __flags) kmem_cache_create("ksm_"#__struct,\ |
| 236 | sizeof(struct __struct), __alignof__(struct __struct),\ |
| 237 | (__flags), NULL) |
| 238 | |
| 239 | static int __init ksm_slab_init(void) |
| 240 | { |
| 241 | rmap_item_cache = KSM_KMEM_CACHE(rmap_item, 0); |
| 242 | if (!rmap_item_cache) |
| 243 | goto out; |
| 244 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 245 | stable_node_cache = KSM_KMEM_CACHE(stable_node, 0); |
| 246 | if (!stable_node_cache) |
| 247 | goto out_free1; |
| 248 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 249 | mm_slot_cache = KSM_KMEM_CACHE(mm_slot, 0); |
| 250 | if (!mm_slot_cache) |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 251 | goto out_free2; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 252 | |
| 253 | return 0; |
| 254 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 255 | out_free2: |
| 256 | kmem_cache_destroy(stable_node_cache); |
| 257 | out_free1: |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 258 | kmem_cache_destroy(rmap_item_cache); |
| 259 | out: |
| 260 | return -ENOMEM; |
| 261 | } |
| 262 | |
| 263 | static void __init ksm_slab_free(void) |
| 264 | { |
| 265 | kmem_cache_destroy(mm_slot_cache); |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 266 | kmem_cache_destroy(stable_node_cache); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 267 | kmem_cache_destroy(rmap_item_cache); |
| 268 | mm_slot_cache = NULL; |
| 269 | } |
| 270 | |
| 271 | static inline struct rmap_item *alloc_rmap_item(void) |
| 272 | { |
Hugh Dickins | 473b0ce | 2009-09-21 17:02:11 -0700 | [diff] [blame] | 273 | struct rmap_item *rmap_item; |
| 274 | |
| 275 | rmap_item = kmem_cache_zalloc(rmap_item_cache, GFP_KERNEL); |
| 276 | if (rmap_item) |
| 277 | ksm_rmap_items++; |
| 278 | return rmap_item; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 279 | } |
| 280 | |
| 281 | static inline void free_rmap_item(struct rmap_item *rmap_item) |
| 282 | { |
Hugh Dickins | 473b0ce | 2009-09-21 17:02:11 -0700 | [diff] [blame] | 283 | ksm_rmap_items--; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 284 | rmap_item->mm = NULL; /* debug safety */ |
| 285 | kmem_cache_free(rmap_item_cache, rmap_item); |
| 286 | } |
| 287 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 288 | static inline struct stable_node *alloc_stable_node(void) |
| 289 | { |
| 290 | return kmem_cache_alloc(stable_node_cache, GFP_KERNEL); |
| 291 | } |
| 292 | |
| 293 | static inline void free_stable_node(struct stable_node *stable_node) |
| 294 | { |
| 295 | kmem_cache_free(stable_node_cache, stable_node); |
| 296 | } |
| 297 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 298 | static inline struct mm_slot *alloc_mm_slot(void) |
| 299 | { |
| 300 | if (!mm_slot_cache) /* initialization failed */ |
| 301 | return NULL; |
| 302 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); |
| 303 | } |
| 304 | |
| 305 | static inline void free_mm_slot(struct mm_slot *mm_slot) |
| 306 | { |
| 307 | kmem_cache_free(mm_slot_cache, mm_slot); |
| 308 | } |
| 309 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 310 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) |
| 311 | { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 312 | struct hlist_node *node; |
Sasha Levin | 4ca3a69 | 2013-02-22 16:32:28 -0800 | [diff] [blame] | 313 | struct mm_slot *slot; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 314 | |
Sasha Levin | 4ca3a69 | 2013-02-22 16:32:28 -0800 | [diff] [blame] | 315 | hash_for_each_possible(mm_slots_hash, slot, node, link, (unsigned long)mm) |
| 316 | if (slot->mm == mm) |
| 317 | return slot; |
| 318 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 319 | return NULL; |
| 320 | } |
| 321 | |
| 322 | static void insert_to_mm_slots_hash(struct mm_struct *mm, |
| 323 | struct mm_slot *mm_slot) |
| 324 | { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 325 | mm_slot->mm = mm; |
Sasha Levin | 4ca3a69 | 2013-02-22 16:32:28 -0800 | [diff] [blame] | 326 | hash_add(mm_slots_hash, &mm_slot->link, (unsigned long)mm); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 327 | } |
| 328 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 329 | /* |
Hugh Dickins | a913e18 | 2009-09-21 17:02:26 -0700 | [diff] [blame] | 330 | * ksmd, and unmerge_and_remove_all_rmap_items(), must not touch an mm's |
| 331 | * page tables after it has passed through ksm_exit() - which, if necessary, |
| 332 | * takes mmap_sem briefly to serialize against them. ksm_exit() does not set |
| 333 | * a special flag: they can just back out as soon as mm_users goes to zero. |
| 334 | * ksm_test_exit() is used throughout to make this test for exit: in some |
| 335 | * places for correctness, in some places just to avoid unnecessary work. |
| 336 | */ |
| 337 | static inline bool ksm_test_exit(struct mm_struct *mm) |
| 338 | { |
| 339 | return atomic_read(&mm->mm_users) == 0; |
| 340 | } |
| 341 | |
| 342 | /* |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 343 | * We use break_ksm to break COW on a ksm page: it's a stripped down |
| 344 | * |
| 345 | * if (get_user_pages(current, mm, addr, 1, 1, 1, &page, NULL) == 1) |
| 346 | * put_page(page); |
| 347 | * |
| 348 | * but taking great care only to touch a ksm page, in a VM_MERGEABLE vma, |
| 349 | * in case the application has unmapped and remapped mm,addr meanwhile. |
| 350 | * Could a ksm page appear anywhere else? Actually yes, in a VM_PFNMAP |
| 351 | * mmap of /dev/mem or /dev/kmem, where we would not want to touch it. |
| 352 | */ |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 353 | static int break_ksm(struct vm_area_struct *vma, unsigned long addr) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 354 | { |
| 355 | struct page *page; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 356 | int ret = 0; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 357 | |
| 358 | do { |
| 359 | cond_resched(); |
| 360 | page = follow_page(vma, addr, FOLL_GET); |
Dan Carpenter | 22eccdd | 2010-04-23 13:18:10 -0400 | [diff] [blame] | 361 | if (IS_ERR_OR_NULL(page)) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 362 | break; |
| 363 | if (PageKsm(page)) |
| 364 | ret = handle_mm_fault(vma->vm_mm, vma, addr, |
| 365 | FAULT_FLAG_WRITE); |
| 366 | else |
| 367 | ret = VM_FAULT_WRITE; |
| 368 | put_page(page); |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 369 | } while (!(ret & (VM_FAULT_WRITE | VM_FAULT_SIGBUS | VM_FAULT_OOM))); |
| 370 | /* |
| 371 | * We must loop because handle_mm_fault() may back out if there's |
| 372 | * any difficulty e.g. if pte accessed bit gets updated concurrently. |
| 373 | * |
| 374 | * VM_FAULT_WRITE is what we have been hoping for: it indicates that |
| 375 | * COW has been broken, even if the vma does not permit VM_WRITE; |
| 376 | * but note that a concurrent fault might break PageKsm for us. |
| 377 | * |
| 378 | * VM_FAULT_SIGBUS could occur if we race with truncation of the |
| 379 | * backing file, which also invalidates anonymous pages: that's |
| 380 | * okay, that truncation will have unmapped the PageKsm for us. |
| 381 | * |
| 382 | * VM_FAULT_OOM: at the time of writing (late July 2009), setting |
| 383 | * aside mem_cgroup limits, VM_FAULT_OOM would only be set if the |
| 384 | * current task has TIF_MEMDIE set, and will be OOM killed on return |
| 385 | * to user; and ksmd, having no mm, would never be chosen for that. |
| 386 | * |
| 387 | * But if the mm is in a limited mem_cgroup, then the fault may fail |
| 388 | * with VM_FAULT_OOM even if the current task is not TIF_MEMDIE; and |
| 389 | * even ksmd can fail in this way - though it's usually breaking ksm |
| 390 | * just to undo a merge it made a moment before, so unlikely to oom. |
| 391 | * |
| 392 | * That's a pity: we might therefore have more kernel pages allocated |
| 393 | * than we're counting as nodes in the stable tree; but ksm_do_scan |
| 394 | * will retry to break_cow on each pass, so should recover the page |
| 395 | * in due course. The important thing is to not let VM_MERGEABLE |
| 396 | * be cleared while any such pages might remain in the area. |
| 397 | */ |
| 398 | return (ret & VM_FAULT_OOM) ? -ENOMEM : 0; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 399 | } |
| 400 | |
Bob Liu | ef69422 | 2012-03-21 16:34:11 -0700 | [diff] [blame] | 401 | static struct vm_area_struct *find_mergeable_vma(struct mm_struct *mm, |
| 402 | unsigned long addr) |
| 403 | { |
| 404 | struct vm_area_struct *vma; |
| 405 | if (ksm_test_exit(mm)) |
| 406 | return NULL; |
| 407 | vma = find_vma(mm, addr); |
| 408 | if (!vma || vma->vm_start > addr) |
| 409 | return NULL; |
| 410 | if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma) |
| 411 | return NULL; |
| 412 | return vma; |
| 413 | } |
| 414 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 415 | static void break_cow(struct rmap_item *rmap_item) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 416 | { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 417 | struct mm_struct *mm = rmap_item->mm; |
| 418 | unsigned long addr = rmap_item->address; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 419 | struct vm_area_struct *vma; |
| 420 | |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 421 | /* |
| 422 | * It is not an accident that whenever we want to break COW |
| 423 | * to undo, we also need to drop a reference to the anon_vma. |
| 424 | */ |
Peter Zijlstra | 9e60109 | 2011-03-22 16:32:46 -0700 | [diff] [blame] | 425 | put_anon_vma(rmap_item->anon_vma); |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 426 | |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 427 | down_read(&mm->mmap_sem); |
Bob Liu | ef69422 | 2012-03-21 16:34:11 -0700 | [diff] [blame] | 428 | vma = find_mergeable_vma(mm, addr); |
| 429 | if (vma) |
| 430 | break_ksm(vma, addr); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 431 | up_read(&mm->mmap_sem); |
| 432 | } |
| 433 | |
Andrea Arcangeli | 29ad768 | 2011-01-13 15:47:19 -0800 | [diff] [blame] | 434 | static struct page *page_trans_compound_anon(struct page *page) |
| 435 | { |
| 436 | if (PageTransCompound(page)) { |
Andrea Arcangeli | 22e5c47 | 2011-01-13 15:47:20 -0800 | [diff] [blame] | 437 | struct page *head = compound_trans_head(page); |
Andrea Arcangeli | 29ad768 | 2011-01-13 15:47:19 -0800 | [diff] [blame] | 438 | /* |
Andrea Arcangeli | 22e5c47 | 2011-01-13 15:47:20 -0800 | [diff] [blame] | 439 | * head may actually be splitted and freed from under |
| 440 | * us but it's ok here. |
Andrea Arcangeli | 29ad768 | 2011-01-13 15:47:19 -0800 | [diff] [blame] | 441 | */ |
Andrea Arcangeli | 29ad768 | 2011-01-13 15:47:19 -0800 | [diff] [blame] | 442 | if (PageAnon(head)) |
| 443 | return head; |
| 444 | } |
| 445 | return NULL; |
| 446 | } |
| 447 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 448 | static struct page *get_mergeable_page(struct rmap_item *rmap_item) |
| 449 | { |
| 450 | struct mm_struct *mm = rmap_item->mm; |
| 451 | unsigned long addr = rmap_item->address; |
| 452 | struct vm_area_struct *vma; |
| 453 | struct page *page; |
| 454 | |
| 455 | down_read(&mm->mmap_sem); |
Bob Liu | ef69422 | 2012-03-21 16:34:11 -0700 | [diff] [blame] | 456 | vma = find_mergeable_vma(mm, addr); |
| 457 | if (!vma) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 458 | goto out; |
| 459 | |
| 460 | page = follow_page(vma, addr, FOLL_GET); |
Dan Carpenter | 22eccdd | 2010-04-23 13:18:10 -0400 | [diff] [blame] | 461 | if (IS_ERR_OR_NULL(page)) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 462 | goto out; |
Andrea Arcangeli | 29ad768 | 2011-01-13 15:47:19 -0800 | [diff] [blame] | 463 | if (PageAnon(page) || page_trans_compound_anon(page)) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 464 | flush_anon_page(vma, page, addr); |
| 465 | flush_dcache_page(page); |
| 466 | } else { |
| 467 | put_page(page); |
| 468 | out: page = NULL; |
| 469 | } |
| 470 | up_read(&mm->mmap_sem); |
| 471 | return page; |
| 472 | } |
| 473 | |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 474 | /* |
| 475 | * This helper is used for getting right index into array of tree roots. |
| 476 | * When merge_across_nodes knob is set to 1, there are only two rb-trees for |
| 477 | * stable and unstable pages from all nodes with roots in index 0. Otherwise, |
| 478 | * every node has its own stable and unstable tree. |
| 479 | */ |
| 480 | static inline int get_kpfn_nid(unsigned long kpfn) |
| 481 | { |
Hugh Dickins | e850dcf | 2013-02-22 16:35:03 -0800 | [diff] [blame] | 482 | return ksm_merge_across_nodes ? 0 : pfn_to_nid(kpfn); |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 483 | } |
| 484 | |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 485 | static void remove_node_from_stable_tree(struct stable_node *stable_node) |
| 486 | { |
| 487 | struct rmap_item *rmap_item; |
| 488 | struct hlist_node *hlist; |
| 489 | |
| 490 | hlist_for_each_entry(rmap_item, hlist, &stable_node->hlist, hlist) { |
| 491 | if (rmap_item->hlist.next) |
| 492 | ksm_pages_sharing--; |
| 493 | else |
| 494 | ksm_pages_shared--; |
Peter Zijlstra | 9e60109 | 2011-03-22 16:32:46 -0700 | [diff] [blame] | 495 | put_anon_vma(rmap_item->anon_vma); |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 496 | rmap_item->address &= PAGE_MASK; |
| 497 | cond_resched(); |
| 498 | } |
| 499 | |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 500 | if (stable_node->head == &migrate_nodes) |
| 501 | list_del(&stable_node->list); |
| 502 | else |
| 503 | rb_erase(&stable_node->node, |
| 504 | &root_stable_tree[NUMA(stable_node->nid)]); |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 505 | free_stable_node(stable_node); |
| 506 | } |
| 507 | |
| 508 | /* |
| 509 | * get_ksm_page: checks if the page indicated by the stable node |
| 510 | * is still its ksm page, despite having held no reference to it. |
| 511 | * In which case we can trust the content of the page, and it |
| 512 | * returns the gotten page; but if the page has now been zapped, |
| 513 | * remove the stale node from the stable tree and return NULL. |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 514 | * But beware, the stable node's page might be being migrated. |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 515 | * |
| 516 | * You would expect the stable_node to hold a reference to the ksm page. |
| 517 | * But if it increments the page's count, swapping out has to wait for |
| 518 | * ksmd to come around again before it can free the page, which may take |
| 519 | * seconds or even minutes: much too unresponsive. So instead we use a |
| 520 | * "keyhole reference": access to the ksm page from the stable node peeps |
| 521 | * out through its keyhole to see if that page still holds the right key, |
| 522 | * pointing back to this stable node. This relies on freeing a PageAnon |
| 523 | * page to reset its page->mapping to NULL, and relies on no other use of |
| 524 | * a page to put something that might look like our key in page->mapping. |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 525 | * is on its way to being freed; but it is an anomaly to bear in mind. |
| 526 | */ |
Hugh Dickins | 8aafa6a | 2013-02-22 16:35:06 -0800 | [diff] [blame] | 527 | static struct page *get_ksm_page(struct stable_node *stable_node, bool locked) |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 528 | { |
| 529 | struct page *page; |
| 530 | void *expected_mapping; |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 531 | unsigned long kpfn; |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 532 | |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 533 | expected_mapping = (void *)stable_node + |
| 534 | (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM); |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 535 | again: |
| 536 | kpfn = ACCESS_ONCE(stable_node->kpfn); |
| 537 | page = pfn_to_page(kpfn); |
| 538 | |
| 539 | /* |
| 540 | * page is computed from kpfn, so on most architectures reading |
| 541 | * page->mapping is naturally ordered after reading node->kpfn, |
| 542 | * but on Alpha we need to be more careful. |
| 543 | */ |
| 544 | smp_read_barrier_depends(); |
| 545 | if (ACCESS_ONCE(page->mapping) != expected_mapping) |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 546 | goto stale; |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 547 | |
| 548 | /* |
| 549 | * We cannot do anything with the page while its refcount is 0. |
| 550 | * Usually 0 means free, or tail of a higher-order page: in which |
| 551 | * case this node is no longer referenced, and should be freed; |
| 552 | * however, it might mean that the page is under page_freeze_refs(). |
| 553 | * The __remove_mapping() case is easy, again the node is now stale; |
| 554 | * but if page is swapcache in migrate_page_move_mapping(), it might |
| 555 | * still be our page, in which case it's essential to keep the node. |
| 556 | */ |
| 557 | while (!get_page_unless_zero(page)) { |
| 558 | /* |
| 559 | * Another check for page->mapping != expected_mapping would |
| 560 | * work here too. We have chosen the !PageSwapCache test to |
| 561 | * optimize the common case, when the page is or is about to |
| 562 | * be freed: PageSwapCache is cleared (under spin_lock_irq) |
| 563 | * in the freeze_refs section of __remove_mapping(); but Anon |
| 564 | * page->mapping reset to NULL later, in free_pages_prepare(). |
| 565 | */ |
| 566 | if (!PageSwapCache(page)) |
| 567 | goto stale; |
| 568 | cpu_relax(); |
| 569 | } |
| 570 | |
| 571 | if (ACCESS_ONCE(page->mapping) != expected_mapping) { |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 572 | put_page(page); |
| 573 | goto stale; |
| 574 | } |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 575 | |
Hugh Dickins | 8aafa6a | 2013-02-22 16:35:06 -0800 | [diff] [blame] | 576 | if (locked) { |
| 577 | lock_page(page); |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 578 | if (ACCESS_ONCE(page->mapping) != expected_mapping) { |
Hugh Dickins | 8aafa6a | 2013-02-22 16:35:06 -0800 | [diff] [blame] | 579 | unlock_page(page); |
| 580 | put_page(page); |
| 581 | goto stale; |
| 582 | } |
| 583 | } |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 584 | return page; |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 585 | |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 586 | stale: |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 587 | /* |
| 588 | * We come here from above when page->mapping or !PageSwapCache |
| 589 | * suggests that the node is stale; but it might be under migration. |
| 590 | * We need smp_rmb(), matching the smp_wmb() in ksm_migrate_page(), |
| 591 | * before checking whether node->kpfn has been changed. |
| 592 | */ |
| 593 | smp_rmb(); |
| 594 | if (ACCESS_ONCE(stable_node->kpfn) != kpfn) |
| 595 | goto again; |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 596 | remove_node_from_stable_tree(stable_node); |
| 597 | return NULL; |
| 598 | } |
| 599 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 600 | /* |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 601 | * Removing rmap_item from stable or unstable tree. |
| 602 | * This function will clean the information from the stable/unstable tree. |
| 603 | */ |
| 604 | static void remove_rmap_item_from_tree(struct rmap_item *rmap_item) |
| 605 | { |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 606 | if (rmap_item->address & STABLE_FLAG) { |
| 607 | struct stable_node *stable_node; |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 608 | struct page *page; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 609 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 610 | stable_node = rmap_item->head; |
Hugh Dickins | 8aafa6a | 2013-02-22 16:35:06 -0800 | [diff] [blame] | 611 | page = get_ksm_page(stable_node, true); |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 612 | if (!page) |
| 613 | goto out; |
| 614 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 615 | hlist_del(&rmap_item->hlist); |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 616 | unlock_page(page); |
| 617 | put_page(page); |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame] | 618 | |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 619 | if (stable_node->hlist.first) |
| 620 | ksm_pages_sharing--; |
| 621 | else |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 622 | ksm_pages_shared--; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 623 | |
Peter Zijlstra | 9e60109 | 2011-03-22 16:32:46 -0700 | [diff] [blame] | 624 | put_anon_vma(rmap_item->anon_vma); |
Hugh Dickins | 93d1771 | 2009-12-14 17:59:16 -0800 | [diff] [blame] | 625 | rmap_item->address &= PAGE_MASK; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 626 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 627 | } else if (rmap_item->address & UNSTABLE_FLAG) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 628 | unsigned char age; |
| 629 | /* |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 630 | * Usually ksmd can and must skip the rb_erase, because |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 631 | * root_unstable_tree was already reset to RB_ROOT. |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 632 | * But be careful when an mm is exiting: do the rb_erase |
| 633 | * if this rmap_item was inserted by this scan, rather |
| 634 | * than left over from before. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 635 | */ |
| 636 | age = (unsigned char)(ksm_scan.seqnr - rmap_item->address); |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 637 | BUG_ON(age > 1); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 638 | if (!age) |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 639 | rb_erase(&rmap_item->node, |
Hugh Dickins | e850dcf | 2013-02-22 16:35:03 -0800 | [diff] [blame] | 640 | &root_unstable_tree[NUMA(rmap_item->nid)]); |
Hugh Dickins | 93d1771 | 2009-12-14 17:59:16 -0800 | [diff] [blame] | 641 | ksm_pages_unshared--; |
| 642 | rmap_item->address &= PAGE_MASK; |
| 643 | } |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 644 | out: |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 645 | cond_resched(); /* we're called from many long loops */ |
| 646 | } |
| 647 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 648 | static void remove_trailing_rmap_items(struct mm_slot *mm_slot, |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 649 | struct rmap_item **rmap_list) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 650 | { |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 651 | while (*rmap_list) { |
| 652 | struct rmap_item *rmap_item = *rmap_list; |
| 653 | *rmap_list = rmap_item->rmap_list; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 654 | remove_rmap_item_from_tree(rmap_item); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 655 | free_rmap_item(rmap_item); |
| 656 | } |
| 657 | } |
| 658 | |
| 659 | /* |
Hugh Dickins | e850dcf | 2013-02-22 16:35:03 -0800 | [diff] [blame] | 660 | * Though it's very tempting to unmerge rmap_items from stable tree rather |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 661 | * than check every pte of a given vma, the locking doesn't quite work for |
| 662 | * that - an rmap_item is assigned to the stable tree after inserting ksm |
| 663 | * page and upping mmap_sem. Nor does it fit with the way we skip dup'ing |
| 664 | * rmap_items from parent to child at fork time (so as not to waste time |
| 665 | * if exit comes before the next scan reaches it). |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 666 | * |
| 667 | * Similarly, although we'd like to remove rmap_items (so updating counts |
| 668 | * and freeing memory) when unmerging an area, it's easier to leave that |
| 669 | * to the next pass of ksmd - consider, for example, how ksmd might be |
| 670 | * 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] | 671 | */ |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 672 | static int unmerge_ksm_pages(struct vm_area_struct *vma, |
| 673 | unsigned long start, unsigned long end) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 674 | { |
| 675 | unsigned long addr; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 676 | int err = 0; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 677 | |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 678 | for (addr = start; addr < end && !err; addr += PAGE_SIZE) { |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 679 | if (ksm_test_exit(vma->vm_mm)) |
| 680 | break; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 681 | if (signal_pending(current)) |
| 682 | err = -ERESTARTSYS; |
| 683 | else |
| 684 | err = break_ksm(vma, addr); |
| 685 | } |
| 686 | return err; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 687 | } |
| 688 | |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 689 | #ifdef CONFIG_SYSFS |
| 690 | /* |
| 691 | * Only called through the sysfs control interface: |
| 692 | */ |
Hugh Dickins | cbf86cf | 2013-02-22 16:35:08 -0800 | [diff] [blame] | 693 | static int remove_stable_node(struct stable_node *stable_node) |
| 694 | { |
| 695 | struct page *page; |
| 696 | int err; |
| 697 | |
| 698 | page = get_ksm_page(stable_node, true); |
| 699 | if (!page) { |
| 700 | /* |
| 701 | * get_ksm_page did remove_node_from_stable_tree itself. |
| 702 | */ |
| 703 | return 0; |
| 704 | } |
| 705 | |
| 706 | if (WARN_ON_ONCE(page_mapped(page))) |
| 707 | err = -EBUSY; |
| 708 | else { |
| 709 | /* |
| 710 | * This page might be in a pagevec waiting to be freed, |
| 711 | * or it might be PageSwapCache (perhaps under writeback), |
| 712 | * or it might have been removed from swapcache a moment ago. |
| 713 | */ |
| 714 | set_page_stable_node(page, NULL); |
| 715 | remove_node_from_stable_tree(stable_node); |
| 716 | err = 0; |
| 717 | } |
| 718 | |
| 719 | unlock_page(page); |
| 720 | put_page(page); |
| 721 | return err; |
| 722 | } |
| 723 | |
| 724 | static int remove_all_stable_nodes(void) |
| 725 | { |
| 726 | struct stable_node *stable_node; |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 727 | struct list_head *this, *next; |
Hugh Dickins | cbf86cf | 2013-02-22 16:35:08 -0800 | [diff] [blame] | 728 | int nid; |
| 729 | int err = 0; |
| 730 | |
| 731 | for (nid = 0; nid < nr_node_ids; nid++) { |
| 732 | while (root_stable_tree[nid].rb_node) { |
| 733 | stable_node = rb_entry(root_stable_tree[nid].rb_node, |
| 734 | struct stable_node, node); |
| 735 | if (remove_stable_node(stable_node)) { |
| 736 | err = -EBUSY; |
| 737 | break; /* proceed to next nid */ |
| 738 | } |
| 739 | cond_resched(); |
| 740 | } |
| 741 | } |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 742 | list_for_each_safe(this, next, &migrate_nodes) { |
| 743 | stable_node = list_entry(this, struct stable_node, list); |
| 744 | if (remove_stable_node(stable_node)) |
| 745 | err = -EBUSY; |
| 746 | cond_resched(); |
| 747 | } |
Hugh Dickins | cbf86cf | 2013-02-22 16:35:08 -0800 | [diff] [blame] | 748 | return err; |
| 749 | } |
| 750 | |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 751 | static int unmerge_and_remove_all_rmap_items(void) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 752 | { |
| 753 | struct mm_slot *mm_slot; |
| 754 | struct mm_struct *mm; |
| 755 | struct vm_area_struct *vma; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 756 | int err = 0; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 757 | |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 758 | spin_lock(&ksm_mmlist_lock); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 759 | ksm_scan.mm_slot = list_entry(ksm_mm_head.mm_list.next, |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 760 | struct mm_slot, mm_list); |
| 761 | spin_unlock(&ksm_mmlist_lock); |
| 762 | |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 763 | for (mm_slot = ksm_scan.mm_slot; |
| 764 | mm_slot != &ksm_mm_head; mm_slot = ksm_scan.mm_slot) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 765 | mm = mm_slot->mm; |
| 766 | down_read(&mm->mmap_sem); |
| 767 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 768 | if (ksm_test_exit(mm)) |
| 769 | break; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 770 | if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma) |
| 771 | continue; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 772 | err = unmerge_ksm_pages(vma, |
| 773 | vma->vm_start, vma->vm_end); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 774 | if (err) |
| 775 | goto error; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 776 | } |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 777 | |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 778 | remove_trailing_rmap_items(mm_slot, &mm_slot->rmap_list); |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 779 | |
| 780 | spin_lock(&ksm_mmlist_lock); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 781 | ksm_scan.mm_slot = list_entry(mm_slot->mm_list.next, |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 782 | struct mm_slot, mm_list); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 783 | if (ksm_test_exit(mm)) { |
Sasha Levin | 4ca3a69 | 2013-02-22 16:32:28 -0800 | [diff] [blame] | 784 | hash_del(&mm_slot->link); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 785 | list_del(&mm_slot->mm_list); |
| 786 | spin_unlock(&ksm_mmlist_lock); |
| 787 | |
| 788 | free_mm_slot(mm_slot); |
| 789 | clear_bit(MMF_VM_MERGEABLE, &mm->flags); |
| 790 | up_read(&mm->mmap_sem); |
| 791 | mmdrop(mm); |
| 792 | } else { |
| 793 | spin_unlock(&ksm_mmlist_lock); |
| 794 | up_read(&mm->mmap_sem); |
| 795 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 796 | } |
| 797 | |
Hugh Dickins | cbf86cf | 2013-02-22 16:35:08 -0800 | [diff] [blame] | 798 | /* Clean up stable nodes, but don't worry if some are still busy */ |
| 799 | remove_all_stable_nodes(); |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 800 | ksm_scan.seqnr = 0; |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 801 | return 0; |
| 802 | |
| 803 | error: |
| 804 | up_read(&mm->mmap_sem); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 805 | spin_lock(&ksm_mmlist_lock); |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 806 | ksm_scan.mm_slot = &ksm_mm_head; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 807 | spin_unlock(&ksm_mmlist_lock); |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 808 | return err; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 809 | } |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 810 | #endif /* CONFIG_SYSFS */ |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 811 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 812 | static u32 calc_checksum(struct page *page) |
| 813 | { |
| 814 | u32 checksum; |
Cong Wang | 9b04c5f | 2011-11-25 23:14:39 +0800 | [diff] [blame] | 815 | void *addr = kmap_atomic(page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 816 | checksum = jhash2(addr, PAGE_SIZE / 4, 17); |
Cong Wang | 9b04c5f | 2011-11-25 23:14:39 +0800 | [diff] [blame] | 817 | kunmap_atomic(addr); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 818 | return checksum; |
| 819 | } |
| 820 | |
| 821 | static int memcmp_pages(struct page *page1, struct page *page2) |
| 822 | { |
| 823 | char *addr1, *addr2; |
| 824 | int ret; |
| 825 | |
Cong Wang | 9b04c5f | 2011-11-25 23:14:39 +0800 | [diff] [blame] | 826 | addr1 = kmap_atomic(page1); |
| 827 | addr2 = kmap_atomic(page2); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 828 | ret = memcmp(addr1, addr2, PAGE_SIZE); |
Cong Wang | 9b04c5f | 2011-11-25 23:14:39 +0800 | [diff] [blame] | 829 | kunmap_atomic(addr2); |
| 830 | kunmap_atomic(addr1); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 831 | return ret; |
| 832 | } |
| 833 | |
| 834 | static inline int pages_identical(struct page *page1, struct page *page2) |
| 835 | { |
| 836 | return !memcmp_pages(page1, page2); |
| 837 | } |
| 838 | |
| 839 | static int write_protect_page(struct vm_area_struct *vma, struct page *page, |
| 840 | pte_t *orig_pte) |
| 841 | { |
| 842 | struct mm_struct *mm = vma->vm_mm; |
| 843 | unsigned long addr; |
| 844 | pte_t *ptep; |
| 845 | spinlock_t *ptl; |
| 846 | int swapped; |
| 847 | int err = -EFAULT; |
Haggai Eran | 6bdb913 | 2012-10-08 16:33:35 -0700 | [diff] [blame] | 848 | unsigned long mmun_start; /* For mmu_notifiers */ |
| 849 | unsigned long mmun_end; /* For mmu_notifiers */ |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 850 | |
| 851 | addr = page_address_in_vma(page, vma); |
| 852 | if (addr == -EFAULT) |
| 853 | goto out; |
| 854 | |
Andrea Arcangeli | 29ad768 | 2011-01-13 15:47:19 -0800 | [diff] [blame] | 855 | BUG_ON(PageTransCompound(page)); |
Haggai Eran | 6bdb913 | 2012-10-08 16:33:35 -0700 | [diff] [blame] | 856 | |
| 857 | mmun_start = addr; |
| 858 | mmun_end = addr + PAGE_SIZE; |
| 859 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
| 860 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 861 | ptep = page_check_address(page, mm, addr, &ptl, 0); |
| 862 | if (!ptep) |
Haggai Eran | 6bdb913 | 2012-10-08 16:33:35 -0700 | [diff] [blame] | 863 | goto out_mn; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 864 | |
Hugh Dickins | 4e31635 | 2010-10-02 17:49:08 -0700 | [diff] [blame] | 865 | if (pte_write(*ptep) || pte_dirty(*ptep)) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 866 | pte_t entry; |
| 867 | |
| 868 | swapped = PageSwapCache(page); |
| 869 | flush_cache_page(vma, addr, page_to_pfn(page)); |
| 870 | /* |
Lucas De Marchi | 25985ed | 2011-03-30 22:57:33 -0300 | [diff] [blame] | 871 | * Ok this is tricky, when get_user_pages_fast() run it doesn't |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 872 | * take any lock, therefore the check that we are going to make |
| 873 | * with the pagecount against the mapcount is racey and |
| 874 | * O_DIRECT can happen right after the check. |
| 875 | * So we clear the pte and flush the tlb before the check |
| 876 | * this assure us that no O_DIRECT can happen after the check |
| 877 | * or in the middle of the check. |
| 878 | */ |
| 879 | entry = ptep_clear_flush(vma, addr, ptep); |
| 880 | /* |
| 881 | * Check that no O_DIRECT or similar I/O is in progress on the |
| 882 | * page |
| 883 | */ |
Hugh Dickins | 31e855e | 2009-12-14 17:59:17 -0800 | [diff] [blame] | 884 | if (page_mapcount(page) + 1 + swapped != page_count(page)) { |
Robin Holt | cb53237 | 2010-03-23 13:35:26 -0700 | [diff] [blame] | 885 | set_pte_at(mm, addr, ptep, entry); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 886 | goto out_unlock; |
| 887 | } |
Hugh Dickins | 4e31635 | 2010-10-02 17:49:08 -0700 | [diff] [blame] | 888 | if (pte_dirty(entry)) |
| 889 | set_page_dirty(page); |
| 890 | entry = pte_mkclean(pte_wrprotect(entry)); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 891 | set_pte_at_notify(mm, addr, ptep, entry); |
| 892 | } |
| 893 | *orig_pte = *ptep; |
| 894 | err = 0; |
| 895 | |
| 896 | out_unlock: |
| 897 | pte_unmap_unlock(ptep, ptl); |
Haggai Eran | 6bdb913 | 2012-10-08 16:33:35 -0700 | [diff] [blame] | 898 | out_mn: |
| 899 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 900 | out: |
| 901 | return err; |
| 902 | } |
| 903 | |
| 904 | /** |
| 905 | * replace_page - replace page in vma by new ksm page |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 906 | * @vma: vma that holds the pte pointing to page |
| 907 | * @page: the page we are replacing by kpage |
| 908 | * @kpage: the ksm page we replace page by |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 909 | * @orig_pte: the original value of the pte |
| 910 | * |
| 911 | * Returns 0 on success, -EFAULT on failure. |
| 912 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 913 | static int replace_page(struct vm_area_struct *vma, struct page *page, |
| 914 | struct page *kpage, pte_t orig_pte) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 915 | { |
| 916 | struct mm_struct *mm = vma->vm_mm; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 917 | pmd_t *pmd; |
| 918 | pte_t *ptep; |
| 919 | spinlock_t *ptl; |
| 920 | unsigned long addr; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 921 | int err = -EFAULT; |
Haggai Eran | 6bdb913 | 2012-10-08 16:33:35 -0700 | [diff] [blame] | 922 | unsigned long mmun_start; /* For mmu_notifiers */ |
| 923 | unsigned long mmun_end; /* For mmu_notifiers */ |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 924 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 925 | addr = page_address_in_vma(page, vma); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 926 | if (addr == -EFAULT) |
| 927 | goto out; |
| 928 | |
Bob Liu | 6219049 | 2012-12-11 16:00:37 -0800 | [diff] [blame] | 929 | pmd = mm_find_pmd(mm, addr); |
| 930 | if (!pmd) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 931 | goto out; |
Andrea Arcangeli | 29ad768 | 2011-01-13 15:47:19 -0800 | [diff] [blame] | 932 | BUG_ON(pmd_trans_huge(*pmd)); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 933 | |
Haggai Eran | 6bdb913 | 2012-10-08 16:33:35 -0700 | [diff] [blame] | 934 | mmun_start = addr; |
| 935 | mmun_end = addr + PAGE_SIZE; |
| 936 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
| 937 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 938 | ptep = pte_offset_map_lock(mm, pmd, addr, &ptl); |
| 939 | if (!pte_same(*ptep, orig_pte)) { |
| 940 | pte_unmap_unlock(ptep, ptl); |
Haggai Eran | 6bdb913 | 2012-10-08 16:33:35 -0700 | [diff] [blame] | 941 | goto out_mn; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 942 | } |
| 943 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 944 | get_page(kpage); |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 945 | page_add_anon_rmap(kpage, vma, addr); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 946 | |
| 947 | flush_cache_page(vma, addr, pte_pfn(*ptep)); |
| 948 | ptep_clear_flush(vma, addr, ptep); |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 949 | 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] | 950 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 951 | page_remove_rmap(page); |
Hugh Dickins | ae52a2a | 2011-01-13 15:46:28 -0800 | [diff] [blame] | 952 | if (!page_mapped(page)) |
| 953 | try_to_free_swap(page); |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 954 | put_page(page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 955 | |
| 956 | pte_unmap_unlock(ptep, ptl); |
| 957 | err = 0; |
Haggai Eran | 6bdb913 | 2012-10-08 16:33:35 -0700 | [diff] [blame] | 958 | out_mn: |
| 959 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 960 | out: |
| 961 | return err; |
| 962 | } |
| 963 | |
Andrea Arcangeli | 29ad768 | 2011-01-13 15:47:19 -0800 | [diff] [blame] | 964 | static int page_trans_compound_anon_split(struct page *page) |
| 965 | { |
| 966 | int ret = 0; |
| 967 | struct page *transhuge_head = page_trans_compound_anon(page); |
| 968 | if (transhuge_head) { |
| 969 | /* Get the reference on the head to split it. */ |
| 970 | if (get_page_unless_zero(transhuge_head)) { |
| 971 | /* |
| 972 | * Recheck we got the reference while the head |
| 973 | * was still anonymous. |
| 974 | */ |
| 975 | if (PageAnon(transhuge_head)) |
| 976 | ret = split_huge_page(transhuge_head); |
| 977 | else |
| 978 | /* |
| 979 | * Retry later if split_huge_page run |
| 980 | * from under us. |
| 981 | */ |
| 982 | ret = 1; |
| 983 | put_page(transhuge_head); |
| 984 | } else |
| 985 | /* Retry later if split_huge_page run from under us. */ |
| 986 | ret = 1; |
| 987 | } |
| 988 | return ret; |
| 989 | } |
| 990 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 991 | /* |
| 992 | * 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] | 993 | * @vma: the vma that holds the pte pointing to page |
| 994 | * @page: the PageAnon page that we want to replace with kpage |
Hugh Dickins | 80e14822 | 2009-12-14 17:59:29 -0800 | [diff] [blame] | 995 | * @kpage: the PageKsm page that we want to map instead of page, |
| 996 | * or NULL the first time when we want to use page as kpage. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 997 | * |
| 998 | * This function returns 0 if the pages were merged, -EFAULT otherwise. |
| 999 | */ |
| 1000 | static int try_to_merge_one_page(struct vm_area_struct *vma, |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1001 | struct page *page, struct page *kpage) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1002 | { |
| 1003 | pte_t orig_pte = __pte(0); |
| 1004 | int err = -EFAULT; |
| 1005 | |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1006 | if (page == kpage) /* ksm page forked */ |
| 1007 | return 0; |
| 1008 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1009 | if (!(vma->vm_flags & VM_MERGEABLE)) |
| 1010 | goto out; |
Andrea Arcangeli | 29ad768 | 2011-01-13 15:47:19 -0800 | [diff] [blame] | 1011 | if (PageTransCompound(page) && page_trans_compound_anon_split(page)) |
| 1012 | goto out; |
| 1013 | BUG_ON(PageTransCompound(page)); |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1014 | if (!PageAnon(page)) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1015 | goto out; |
| 1016 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1017 | /* |
| 1018 | * We need the page lock to read a stable PageSwapCache in |
| 1019 | * write_protect_page(). We use trylock_page() instead of |
| 1020 | * lock_page() because we don't want to wait here - we |
| 1021 | * prefer to continue scanning and merging different pages, |
| 1022 | * then come back to this page when it is unlocked. |
| 1023 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1024 | if (!trylock_page(page)) |
Hugh Dickins | 31e855e | 2009-12-14 17:59:17 -0800 | [diff] [blame] | 1025 | goto out; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1026 | /* |
| 1027 | * If this anonymous page is mapped only here, its pte may need |
| 1028 | * to be write-protected. If it's mapped elsewhere, all of its |
| 1029 | * ptes are necessarily already write-protected. But in either |
| 1030 | * case, we need to lock and check page_count is not raised. |
| 1031 | */ |
Hugh Dickins | 80e14822 | 2009-12-14 17:59:29 -0800 | [diff] [blame] | 1032 | if (write_protect_page(vma, page, &orig_pte) == 0) { |
| 1033 | if (!kpage) { |
| 1034 | /* |
| 1035 | * While we hold page lock, upgrade page from |
| 1036 | * PageAnon+anon_vma to PageKsm+NULL stable_node: |
| 1037 | * stable_tree_insert() will update stable_node. |
| 1038 | */ |
| 1039 | set_page_stable_node(page, NULL); |
| 1040 | mark_page_accessed(page); |
| 1041 | err = 0; |
| 1042 | } else if (pages_identical(page, kpage)) |
| 1043 | err = replace_page(vma, page, kpage, orig_pte); |
| 1044 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1045 | |
Hugh Dickins | 80e14822 | 2009-12-14 17:59:29 -0800 | [diff] [blame] | 1046 | if ((vma->vm_flags & VM_LOCKED) && kpage && !err) { |
Hugh Dickins | 73848b4 | 2009-12-14 17:59:22 -0800 | [diff] [blame] | 1047 | munlock_vma_page(page); |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1048 | if (!PageMlocked(kpage)) { |
| 1049 | unlock_page(page); |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1050 | lock_page(kpage); |
| 1051 | mlock_vma_page(kpage); |
| 1052 | page = kpage; /* for final unlock */ |
| 1053 | } |
| 1054 | } |
Hugh Dickins | 73848b4 | 2009-12-14 17:59:22 -0800 | [diff] [blame] | 1055 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1056 | unlock_page(page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1057 | out: |
| 1058 | return err; |
| 1059 | } |
| 1060 | |
| 1061 | /* |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 1062 | * try_to_merge_with_ksm_page - like try_to_merge_two_pages, |
| 1063 | * 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] | 1064 | * |
| 1065 | * This function returns 0 if the pages were merged, -EFAULT otherwise. |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 1066 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1067 | static int try_to_merge_with_ksm_page(struct rmap_item *rmap_item, |
| 1068 | struct page *page, struct page *kpage) |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 1069 | { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1070 | struct mm_struct *mm = rmap_item->mm; |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 1071 | struct vm_area_struct *vma; |
| 1072 | int err = -EFAULT; |
| 1073 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1074 | down_read(&mm->mmap_sem); |
| 1075 | if (ksm_test_exit(mm)) |
| 1076 | goto out; |
| 1077 | vma = find_vma(mm, rmap_item->address); |
| 1078 | if (!vma || vma->vm_start > rmap_item->address) |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1079 | goto out; |
| 1080 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1081 | err = try_to_merge_one_page(vma, page, kpage); |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1082 | if (err) |
| 1083 | goto out; |
| 1084 | |
| 1085 | /* Must get reference to anon_vma while still holding mmap_sem */ |
Peter Zijlstra | 9e60109 | 2011-03-22 16:32:46 -0700 | [diff] [blame] | 1086 | rmap_item->anon_vma = vma->anon_vma; |
| 1087 | get_anon_vma(vma->anon_vma); |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 1088 | out: |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1089 | up_read(&mm->mmap_sem); |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 1090 | return err; |
| 1091 | } |
| 1092 | |
| 1093 | /* |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1094 | * try_to_merge_two_pages - take two identical pages and prepare them |
| 1095 | * to be merged into one page. |
| 1096 | * |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1097 | * This function returns the kpage if we successfully merged two identical |
| 1098 | * pages into one ksm page, NULL otherwise. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1099 | * |
Hugh Dickins | 80e14822 | 2009-12-14 17:59:29 -0800 | [diff] [blame] | 1100 | * Note that this function upgrades page to ksm page: if one of the pages |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1101 | * is already a ksm page, try_to_merge_with_ksm_page should be used. |
| 1102 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1103 | static struct page *try_to_merge_two_pages(struct rmap_item *rmap_item, |
| 1104 | struct page *page, |
| 1105 | struct rmap_item *tree_rmap_item, |
| 1106 | struct page *tree_page) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1107 | { |
Hugh Dickins | 80e14822 | 2009-12-14 17:59:29 -0800 | [diff] [blame] | 1108 | int err; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1109 | |
Hugh Dickins | 80e14822 | 2009-12-14 17:59:29 -0800 | [diff] [blame] | 1110 | err = try_to_merge_with_ksm_page(rmap_item, page, NULL); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1111 | if (!err) { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1112 | err = try_to_merge_with_ksm_page(tree_rmap_item, |
Hugh Dickins | 80e14822 | 2009-12-14 17:59:29 -0800 | [diff] [blame] | 1113 | tree_page, page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1114 | /* |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 1115 | * If that fails, we have a ksm page with only one pte |
| 1116 | * pointing to it: so break it. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1117 | */ |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 1118 | if (err) |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1119 | break_cow(rmap_item); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1120 | } |
Hugh Dickins | 80e14822 | 2009-12-14 17:59:29 -0800 | [diff] [blame] | 1121 | return err ? NULL : page; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1122 | } |
| 1123 | |
| 1124 | /* |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1125 | * stable_tree_search - search for page inside the stable tree |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1126 | * |
| 1127 | * This function checks if there is a page inside the stable tree |
| 1128 | * with identical content to the page that we are scanning right now. |
| 1129 | * |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1130 | * This function returns the stable tree node of identical content if found, |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1131 | * NULL otherwise. |
| 1132 | */ |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 1133 | static struct page *stable_tree_search(struct page *page) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1134 | { |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 1135 | int nid; |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1136 | struct rb_node **new; |
| 1137 | struct rb_node *parent; |
| 1138 | struct stable_node *stable_node; |
| 1139 | struct stable_node *page_node; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1140 | |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1141 | page_node = page_stable_node(page); |
| 1142 | if (page_node && page_node->head != &migrate_nodes) { |
| 1143 | /* ksm page forked */ |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame] | 1144 | get_page(page); |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 1145 | return page; |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame] | 1146 | } |
| 1147 | |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 1148 | nid = get_kpfn_nid(page_to_pfn(page)); |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1149 | again: |
| 1150 | new = &root_stable_tree[nid].rb_node; |
| 1151 | parent = NULL; |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 1152 | |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1153 | while (*new) { |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 1154 | struct page *tree_page; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1155 | int ret; |
| 1156 | |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame] | 1157 | cond_resched(); |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1158 | stable_node = rb_entry(*new, struct stable_node, node); |
Hugh Dickins | 8aafa6a | 2013-02-22 16:35:06 -0800 | [diff] [blame] | 1159 | tree_page = get_ksm_page(stable_node, false); |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 1160 | if (!tree_page) |
| 1161 | return NULL; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1162 | |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 1163 | ret = memcmp_pages(page, tree_page); |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 1164 | put_page(tree_page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1165 | |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1166 | parent = *new; |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 1167 | if (ret < 0) |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1168 | new = &parent->rb_left; |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 1169 | else if (ret > 0) |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1170 | new = &parent->rb_right; |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 1171 | else { |
| 1172 | /* |
| 1173 | * Lock and unlock the stable_node's page (which |
| 1174 | * might already have been migrated) so that page |
| 1175 | * migration is sure to notice its raised count. |
| 1176 | * It would be more elegant to return stable_node |
| 1177 | * than kpage, but that involves more changes. |
| 1178 | */ |
| 1179 | tree_page = get_ksm_page(stable_node, true); |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1180 | if (tree_page) { |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 1181 | unlock_page(tree_page); |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1182 | if (get_kpfn_nid(stable_node->kpfn) != |
| 1183 | NUMA(stable_node->nid)) { |
| 1184 | put_page(tree_page); |
| 1185 | goto replace; |
| 1186 | } |
| 1187 | return tree_page; |
| 1188 | } |
| 1189 | /* |
| 1190 | * There is now a place for page_node, but the tree may |
| 1191 | * have been rebalanced, so re-evaluate parent and new. |
| 1192 | */ |
| 1193 | if (page_node) |
| 1194 | goto again; |
| 1195 | return NULL; |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 1196 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1197 | } |
| 1198 | |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1199 | if (!page_node) |
| 1200 | return NULL; |
| 1201 | |
| 1202 | list_del(&page_node->list); |
| 1203 | DO_NUMA(page_node->nid = nid); |
| 1204 | rb_link_node(&page_node->node, parent, new); |
| 1205 | rb_insert_color(&page_node->node, &root_stable_tree[nid]); |
| 1206 | get_page(page); |
| 1207 | return page; |
| 1208 | |
| 1209 | replace: |
| 1210 | if (page_node) { |
| 1211 | list_del(&page_node->list); |
| 1212 | DO_NUMA(page_node->nid = nid); |
| 1213 | rb_replace_node(&stable_node->node, |
| 1214 | &page_node->node, &root_stable_tree[nid]); |
| 1215 | get_page(page); |
| 1216 | } else { |
| 1217 | rb_erase(&stable_node->node, &root_stable_tree[nid]); |
| 1218 | page = NULL; |
| 1219 | } |
| 1220 | stable_node->head = &migrate_nodes; |
| 1221 | list_add(&stable_node->list, stable_node->head); |
| 1222 | return page; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1223 | } |
| 1224 | |
| 1225 | /* |
Hugh Dickins | e850dcf | 2013-02-22 16:35:03 -0800 | [diff] [blame] | 1226 | * stable_tree_insert - insert stable tree node pointing to new ksm page |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1227 | * into the stable tree. |
| 1228 | * |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1229 | * This function returns the stable tree node just allocated on success, |
| 1230 | * NULL otherwise. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1231 | */ |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1232 | static struct stable_node *stable_tree_insert(struct page *kpage) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1233 | { |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 1234 | int nid; |
| 1235 | unsigned long kpfn; |
| 1236 | struct rb_node **new; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1237 | struct rb_node *parent = NULL; |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1238 | struct stable_node *stable_node; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1239 | |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 1240 | kpfn = page_to_pfn(kpage); |
| 1241 | nid = get_kpfn_nid(kpfn); |
| 1242 | new = &root_stable_tree[nid].rb_node; |
| 1243 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1244 | while (*new) { |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 1245 | struct page *tree_page; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1246 | int ret; |
| 1247 | |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame] | 1248 | cond_resched(); |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1249 | stable_node = rb_entry(*new, struct stable_node, node); |
Hugh Dickins | 8aafa6a | 2013-02-22 16:35:06 -0800 | [diff] [blame] | 1250 | tree_page = get_ksm_page(stable_node, false); |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 1251 | if (!tree_page) |
| 1252 | return NULL; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1253 | |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 1254 | ret = memcmp_pages(kpage, tree_page); |
| 1255 | put_page(tree_page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1256 | |
| 1257 | parent = *new; |
| 1258 | if (ret < 0) |
| 1259 | new = &parent->rb_left; |
| 1260 | else if (ret > 0) |
| 1261 | new = &parent->rb_right; |
| 1262 | else { |
| 1263 | /* |
| 1264 | * It is not a bug that stable_tree_search() didn't |
| 1265 | * find this node: because at that time our page was |
| 1266 | * not yet write-protected, so may have changed since. |
| 1267 | */ |
| 1268 | return NULL; |
| 1269 | } |
| 1270 | } |
| 1271 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1272 | stable_node = alloc_stable_node(); |
| 1273 | if (!stable_node) |
| 1274 | return NULL; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1275 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1276 | INIT_HLIST_HEAD(&stable_node->hlist); |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 1277 | stable_node->kpfn = kpfn; |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame] | 1278 | set_page_stable_node(kpage, stable_node); |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1279 | DO_NUMA(stable_node->nid = nid); |
Hugh Dickins | e850dcf | 2013-02-22 16:35:03 -0800 | [diff] [blame] | 1280 | rb_link_node(&stable_node->node, parent, new); |
| 1281 | rb_insert_color(&stable_node->node, &root_stable_tree[nid]); |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame] | 1282 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1283 | return stable_node; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1284 | } |
| 1285 | |
| 1286 | /* |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1287 | * unstable_tree_search_insert - search for identical page, |
| 1288 | * else insert rmap_item into the unstable tree. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1289 | * |
| 1290 | * This function searches for a page in the unstable tree identical to the |
| 1291 | * page currently being scanned; and if no identical page is found in the |
| 1292 | * tree, we insert rmap_item as a new object into the unstable tree. |
| 1293 | * |
| 1294 | * This function returns pointer to rmap_item found to be identical |
| 1295 | * to the currently scanned page, NULL otherwise. |
| 1296 | * |
| 1297 | * This function does both searching and inserting, because they share |
| 1298 | * the same walking algorithm in an rbtree. |
| 1299 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1300 | static |
| 1301 | struct rmap_item *unstable_tree_search_insert(struct rmap_item *rmap_item, |
| 1302 | struct page *page, |
| 1303 | struct page **tree_pagep) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1304 | { |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 1305 | struct rb_node **new; |
| 1306 | struct rb_root *root; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1307 | struct rb_node *parent = NULL; |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 1308 | int nid; |
| 1309 | |
| 1310 | nid = get_kpfn_nid(page_to_pfn(page)); |
| 1311 | root = &root_unstable_tree[nid]; |
| 1312 | new = &root->rb_node; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1313 | |
| 1314 | while (*new) { |
| 1315 | struct rmap_item *tree_rmap_item; |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1316 | struct page *tree_page; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1317 | int ret; |
| 1318 | |
Hugh Dickins | d178f27 | 2009-11-09 15:58:23 +0000 | [diff] [blame] | 1319 | cond_resched(); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1320 | tree_rmap_item = rb_entry(*new, struct rmap_item, node); |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1321 | tree_page = get_mergeable_page(tree_rmap_item); |
Dan Carpenter | 22eccdd | 2010-04-23 13:18:10 -0400 | [diff] [blame] | 1322 | if (IS_ERR_OR_NULL(tree_page)) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1323 | return NULL; |
| 1324 | |
| 1325 | /* |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1326 | * Don't substitute a ksm page for a forked page. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1327 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1328 | if (page == tree_page) { |
| 1329 | put_page(tree_page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1330 | return NULL; |
| 1331 | } |
| 1332 | |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 1333 | /* |
| 1334 | * If tree_page has been migrated to another NUMA node, it |
| 1335 | * will be flushed out and put into the right unstable tree |
| 1336 | * next time: only merge with it if merge_across_nodes. |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 1337 | */ |
| 1338 | if (!ksm_merge_across_nodes && page_to_nid(tree_page) != nid) { |
| 1339 | put_page(tree_page); |
| 1340 | return NULL; |
| 1341 | } |
| 1342 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1343 | ret = memcmp_pages(page, tree_page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1344 | |
| 1345 | parent = *new; |
| 1346 | if (ret < 0) { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1347 | put_page(tree_page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1348 | new = &parent->rb_left; |
| 1349 | } else if (ret > 0) { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1350 | put_page(tree_page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1351 | new = &parent->rb_right; |
| 1352 | } else { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1353 | *tree_pagep = tree_page; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1354 | return tree_rmap_item; |
| 1355 | } |
| 1356 | } |
| 1357 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1358 | rmap_item->address |= UNSTABLE_FLAG; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1359 | rmap_item->address |= (ksm_scan.seqnr & SEQNR_MASK); |
Hugh Dickins | e850dcf | 2013-02-22 16:35:03 -0800 | [diff] [blame] | 1360 | DO_NUMA(rmap_item->nid = nid); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1361 | rb_link_node(&rmap_item->node, parent, new); |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 1362 | rb_insert_color(&rmap_item->node, root); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1363 | |
Hugh Dickins | 473b0ce | 2009-09-21 17:02:11 -0700 | [diff] [blame] | 1364 | ksm_pages_unshared++; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1365 | return NULL; |
| 1366 | } |
| 1367 | |
| 1368 | /* |
| 1369 | * stable_tree_append - add another rmap_item to the linked list of |
| 1370 | * rmap_items hanging off a given node of the stable tree, all sharing |
| 1371 | * the same ksm page. |
| 1372 | */ |
| 1373 | static void stable_tree_append(struct rmap_item *rmap_item, |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1374 | struct stable_node *stable_node) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1375 | { |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1376 | rmap_item->head = stable_node; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1377 | rmap_item->address |= STABLE_FLAG; |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1378 | hlist_add_head(&rmap_item->hlist, &stable_node->hlist); |
Hugh Dickins | e178dfd | 2009-09-21 17:02:10 -0700 | [diff] [blame] | 1379 | |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1380 | if (rmap_item->hlist.next) |
| 1381 | ksm_pages_sharing++; |
| 1382 | else |
| 1383 | ksm_pages_shared++; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1384 | } |
| 1385 | |
| 1386 | /* |
Hugh Dickins | 81464e30 | 2009-09-21 17:02:15 -0700 | [diff] [blame] | 1387 | * cmp_and_merge_page - first see if page can be merged into the stable tree; |
| 1388 | * if not, compare checksum to previous and if it's the same, see if page can |
| 1389 | * be inserted into the unstable tree, or merged with a page already there and |
| 1390 | * both transferred to the stable tree. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1391 | * |
| 1392 | * @page: the page that we are searching identical page to. |
| 1393 | * @rmap_item: the reverse mapping into the virtual address of this page |
| 1394 | */ |
| 1395 | static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item) |
| 1396 | { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1397 | struct rmap_item *tree_rmap_item; |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1398 | struct page *tree_page = NULL; |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1399 | struct stable_node *stable_node; |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1400 | struct page *kpage; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1401 | unsigned int checksum; |
| 1402 | int err; |
| 1403 | |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1404 | stable_node = page_stable_node(page); |
| 1405 | if (stable_node) { |
| 1406 | if (stable_node->head != &migrate_nodes && |
| 1407 | get_kpfn_nid(stable_node->kpfn) != NUMA(stable_node->nid)) { |
| 1408 | rb_erase(&stable_node->node, |
| 1409 | &root_stable_tree[NUMA(stable_node->nid)]); |
| 1410 | stable_node->head = &migrate_nodes; |
| 1411 | list_add(&stable_node->list, stable_node->head); |
| 1412 | } |
| 1413 | if (stable_node->head != &migrate_nodes && |
| 1414 | rmap_item->head == stable_node) |
| 1415 | return; |
| 1416 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1417 | |
| 1418 | /* We first start with searching the page inside the stable tree */ |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 1419 | kpage = stable_tree_search(page); |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1420 | if (kpage == page && rmap_item->head == stable_node) { |
| 1421 | put_page(kpage); |
| 1422 | return; |
| 1423 | } |
| 1424 | |
| 1425 | remove_rmap_item_from_tree(rmap_item); |
| 1426 | |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 1427 | if (kpage) { |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame] | 1428 | err = try_to_merge_with_ksm_page(rmap_item, page, kpage); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1429 | if (!err) { |
| 1430 | /* |
| 1431 | * The page was successfully merged: |
| 1432 | * add its rmap_item to the stable tree. |
| 1433 | */ |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1434 | lock_page(kpage); |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 1435 | stable_tree_append(rmap_item, page_stable_node(kpage)); |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1436 | unlock_page(kpage); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1437 | } |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1438 | put_page(kpage); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1439 | return; |
| 1440 | } |
| 1441 | |
| 1442 | /* |
Hugh Dickins | 4035c07a | 2009-12-14 17:59:27 -0800 | [diff] [blame] | 1443 | * If the hash value of the page has changed from the last time |
| 1444 | * we calculated it, this page is changing frequently: therefore we |
| 1445 | * don't want to insert it in the unstable tree, and we don't want |
| 1446 | * to waste our time searching for something identical to it there. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1447 | */ |
| 1448 | checksum = calc_checksum(page); |
| 1449 | if (rmap_item->oldchecksum != checksum) { |
| 1450 | rmap_item->oldchecksum = checksum; |
| 1451 | return; |
| 1452 | } |
| 1453 | |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1454 | tree_rmap_item = |
| 1455 | unstable_tree_search_insert(rmap_item, page, &tree_page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1456 | if (tree_rmap_item) { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1457 | kpage = try_to_merge_two_pages(rmap_item, page, |
| 1458 | tree_rmap_item, tree_page); |
| 1459 | put_page(tree_page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1460 | /* |
| 1461 | * As soon as we merge this page, we want to remove the |
| 1462 | * rmap_item of the page we have merged with from the unstable |
| 1463 | * tree, and insert it instead as new node in the stable tree. |
| 1464 | */ |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1465 | if (kpage) { |
Hugh Dickins | 93d1771 | 2009-12-14 17:59:16 -0800 | [diff] [blame] | 1466 | remove_rmap_item_from_tree(tree_rmap_item); |
Hugh Dickins | 473b0ce | 2009-09-21 17:02:11 -0700 | [diff] [blame] | 1467 | |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1468 | lock_page(kpage); |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1469 | stable_node = stable_tree_insert(kpage); |
| 1470 | if (stable_node) { |
| 1471 | stable_tree_append(tree_rmap_item, stable_node); |
| 1472 | stable_tree_append(rmap_item, stable_node); |
| 1473 | } |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1474 | unlock_page(kpage); |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1475 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1476 | /* |
| 1477 | * If we fail to insert the page into the stable tree, |
| 1478 | * we will have 2 virtual addresses that are pointing |
| 1479 | * to a ksm page left outside the stable tree, |
| 1480 | * in which case we need to break_cow on both. |
| 1481 | */ |
Hugh Dickins | 7b6ba2c | 2009-12-14 17:59:20 -0800 | [diff] [blame] | 1482 | if (!stable_node) { |
Hugh Dickins | 8dd3557 | 2009-12-14 17:59:18 -0800 | [diff] [blame] | 1483 | break_cow(tree_rmap_item); |
| 1484 | break_cow(rmap_item); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1485 | } |
| 1486 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1487 | } |
| 1488 | } |
| 1489 | |
| 1490 | 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] | 1491 | struct rmap_item **rmap_list, |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1492 | unsigned long addr) |
| 1493 | { |
| 1494 | struct rmap_item *rmap_item; |
| 1495 | |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1496 | while (*rmap_list) { |
| 1497 | rmap_item = *rmap_list; |
Hugh Dickins | 93d1771 | 2009-12-14 17:59:16 -0800 | [diff] [blame] | 1498 | if ((rmap_item->address & PAGE_MASK) == addr) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1499 | return rmap_item; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1500 | if (rmap_item->address > addr) |
| 1501 | break; |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1502 | *rmap_list = rmap_item->rmap_list; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1503 | remove_rmap_item_from_tree(rmap_item); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1504 | free_rmap_item(rmap_item); |
| 1505 | } |
| 1506 | |
| 1507 | rmap_item = alloc_rmap_item(); |
| 1508 | if (rmap_item) { |
| 1509 | /* It has already been zeroed */ |
| 1510 | rmap_item->mm = mm_slot->mm; |
| 1511 | rmap_item->address = addr; |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1512 | rmap_item->rmap_list = *rmap_list; |
| 1513 | *rmap_list = rmap_item; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1514 | } |
| 1515 | return rmap_item; |
| 1516 | } |
| 1517 | |
| 1518 | static struct rmap_item *scan_get_next_rmap_item(struct page **page) |
| 1519 | { |
| 1520 | struct mm_struct *mm; |
| 1521 | struct mm_slot *slot; |
| 1522 | struct vm_area_struct *vma; |
| 1523 | struct rmap_item *rmap_item; |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 1524 | int nid; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1525 | |
| 1526 | if (list_empty(&ksm_mm_head.mm_list)) |
| 1527 | return NULL; |
| 1528 | |
| 1529 | slot = ksm_scan.mm_slot; |
| 1530 | if (slot == &ksm_mm_head) { |
Hugh Dickins | 2919bfd | 2011-01-13 15:47:29 -0800 | [diff] [blame] | 1531 | /* |
| 1532 | * A number of pages can hang around indefinitely on per-cpu |
| 1533 | * pagevecs, raised page count preventing write_protect_page |
| 1534 | * from merging them. Though it doesn't really matter much, |
| 1535 | * it is puzzling to see some stuck in pages_volatile until |
| 1536 | * other activity jostles them out, and they also prevented |
| 1537 | * LTP's KSM test from succeeding deterministically; so drain |
| 1538 | * them here (here rather than on entry to ksm_do_scan(), |
| 1539 | * so we don't IPI too often when pages_to_scan is set low). |
| 1540 | */ |
| 1541 | lru_add_drain_all(); |
| 1542 | |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1543 | /* |
| 1544 | * Whereas stale stable_nodes on the stable_tree itself |
| 1545 | * get pruned in the regular course of stable_tree_search(), |
| 1546 | * those moved out to the migrate_nodes list can accumulate: |
| 1547 | * so prune them once before each full scan. |
| 1548 | */ |
| 1549 | if (!ksm_merge_across_nodes) { |
| 1550 | struct stable_node *stable_node; |
| 1551 | struct list_head *this, *next; |
| 1552 | struct page *page; |
| 1553 | |
| 1554 | list_for_each_safe(this, next, &migrate_nodes) { |
| 1555 | stable_node = list_entry(this, |
| 1556 | struct stable_node, list); |
| 1557 | page = get_ksm_page(stable_node, false); |
| 1558 | if (page) |
| 1559 | put_page(page); |
| 1560 | cond_resched(); |
| 1561 | } |
| 1562 | } |
| 1563 | |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 1564 | for (nid = 0; nid < nr_node_ids; nid++) |
| 1565 | root_unstable_tree[nid] = RB_ROOT; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1566 | |
| 1567 | spin_lock(&ksm_mmlist_lock); |
| 1568 | slot = list_entry(slot->mm_list.next, struct mm_slot, mm_list); |
| 1569 | ksm_scan.mm_slot = slot; |
| 1570 | spin_unlock(&ksm_mmlist_lock); |
Hugh Dickins | 2b47261 | 2011-06-15 15:08:58 -0700 | [diff] [blame] | 1571 | /* |
| 1572 | * Although we tested list_empty() above, a racing __ksm_exit |
| 1573 | * of the last mm on the list may have removed it since then. |
| 1574 | */ |
| 1575 | if (slot == &ksm_mm_head) |
| 1576 | return NULL; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1577 | next_mm: |
| 1578 | ksm_scan.address = 0; |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1579 | ksm_scan.rmap_list = &slot->rmap_list; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1580 | } |
| 1581 | |
| 1582 | mm = slot->mm; |
| 1583 | down_read(&mm->mmap_sem); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1584 | if (ksm_test_exit(mm)) |
| 1585 | vma = NULL; |
| 1586 | else |
| 1587 | vma = find_vma(mm, ksm_scan.address); |
| 1588 | |
| 1589 | for (; vma; vma = vma->vm_next) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1590 | if (!(vma->vm_flags & VM_MERGEABLE)) |
| 1591 | continue; |
| 1592 | if (ksm_scan.address < vma->vm_start) |
| 1593 | ksm_scan.address = vma->vm_start; |
| 1594 | if (!vma->anon_vma) |
| 1595 | ksm_scan.address = vma->vm_end; |
| 1596 | |
| 1597 | while (ksm_scan.address < vma->vm_end) { |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1598 | if (ksm_test_exit(mm)) |
| 1599 | break; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1600 | *page = follow_page(vma, ksm_scan.address, FOLL_GET); |
Andrea Arcangeli | 21ae5b0 | 2011-01-13 15:47:00 -0800 | [diff] [blame] | 1601 | if (IS_ERR_OR_NULL(*page)) { |
| 1602 | ksm_scan.address += PAGE_SIZE; |
| 1603 | cond_resched(); |
| 1604 | continue; |
| 1605 | } |
Andrea Arcangeli | 29ad768 | 2011-01-13 15:47:19 -0800 | [diff] [blame] | 1606 | if (PageAnon(*page) || |
| 1607 | page_trans_compound_anon(*page)) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1608 | flush_anon_page(vma, *page, ksm_scan.address); |
| 1609 | flush_dcache_page(*page); |
| 1610 | rmap_item = get_next_rmap_item(slot, |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1611 | ksm_scan.rmap_list, ksm_scan.address); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1612 | if (rmap_item) { |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1613 | ksm_scan.rmap_list = |
| 1614 | &rmap_item->rmap_list; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1615 | ksm_scan.address += PAGE_SIZE; |
| 1616 | } else |
| 1617 | put_page(*page); |
| 1618 | up_read(&mm->mmap_sem); |
| 1619 | return rmap_item; |
| 1620 | } |
Andrea Arcangeli | 21ae5b0 | 2011-01-13 15:47:00 -0800 | [diff] [blame] | 1621 | put_page(*page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1622 | ksm_scan.address += PAGE_SIZE; |
| 1623 | cond_resched(); |
| 1624 | } |
| 1625 | } |
| 1626 | |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1627 | if (ksm_test_exit(mm)) { |
| 1628 | ksm_scan.address = 0; |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1629 | ksm_scan.rmap_list = &slot->rmap_list; |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1630 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1631 | /* |
| 1632 | * Nuke all the rmap_items that are above this current rmap: |
| 1633 | * because there were no VM_MERGEABLE vmas with such addresses. |
| 1634 | */ |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1635 | remove_trailing_rmap_items(slot, ksm_scan.rmap_list); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1636 | |
| 1637 | spin_lock(&ksm_mmlist_lock); |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1638 | ksm_scan.mm_slot = list_entry(slot->mm_list.next, |
| 1639 | struct mm_slot, mm_list); |
| 1640 | if (ksm_scan.address == 0) { |
| 1641 | /* |
| 1642 | * We've completed a full scan of all vmas, holding mmap_sem |
| 1643 | * throughout, and found no VM_MERGEABLE: so do the same as |
| 1644 | * __ksm_exit does to remove this mm from all our lists now. |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1645 | * This applies either when cleaning up after __ksm_exit |
| 1646 | * (but beware: we can reach here even before __ksm_exit), |
| 1647 | * or when all VM_MERGEABLE areas have been unmapped (and |
| 1648 | * mmap_sem then protects against race with MADV_MERGEABLE). |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1649 | */ |
Sasha Levin | 4ca3a69 | 2013-02-22 16:32:28 -0800 | [diff] [blame] | 1650 | hash_del(&slot->link); |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1651 | list_del(&slot->mm_list); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1652 | spin_unlock(&ksm_mmlist_lock); |
| 1653 | |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1654 | free_mm_slot(slot); |
| 1655 | clear_bit(MMF_VM_MERGEABLE, &mm->flags); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1656 | up_read(&mm->mmap_sem); |
| 1657 | mmdrop(mm); |
| 1658 | } else { |
| 1659 | spin_unlock(&ksm_mmlist_lock); |
| 1660 | up_read(&mm->mmap_sem); |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1661 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1662 | |
| 1663 | /* Repeat until we've completed scanning the whole list */ |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1664 | slot = ksm_scan.mm_slot; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1665 | if (slot != &ksm_mm_head) |
| 1666 | goto next_mm; |
| 1667 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1668 | ksm_scan.seqnr++; |
| 1669 | return NULL; |
| 1670 | } |
| 1671 | |
| 1672 | /** |
| 1673 | * ksm_do_scan - the ksm scanner main worker function. |
| 1674 | * @scan_npages - number of pages we want to scan before we return. |
| 1675 | */ |
| 1676 | static void ksm_do_scan(unsigned int scan_npages) |
| 1677 | { |
| 1678 | struct rmap_item *rmap_item; |
Dan Carpenter | 22eccdd | 2010-04-23 13:18:10 -0400 | [diff] [blame] | 1679 | struct page *uninitialized_var(page); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1680 | |
Andrea Arcangeli | 878aee7 | 2011-01-13 15:47:10 -0800 | [diff] [blame] | 1681 | while (scan_npages-- && likely(!freezing(current))) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1682 | cond_resched(); |
| 1683 | rmap_item = scan_get_next_rmap_item(&page); |
| 1684 | if (!rmap_item) |
| 1685 | return; |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 1686 | cmp_and_merge_page(page, rmap_item); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1687 | put_page(page); |
| 1688 | } |
| 1689 | } |
| 1690 | |
Hugh Dickins | 6e158384 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1691 | static int ksmd_should_run(void) |
| 1692 | { |
| 1693 | return (ksm_run & KSM_RUN_MERGE) && !list_empty(&ksm_mm_head.mm_list); |
| 1694 | } |
| 1695 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1696 | static int ksm_scan_thread(void *nothing) |
| 1697 | { |
Andrea Arcangeli | 878aee7 | 2011-01-13 15:47:10 -0800 | [diff] [blame] | 1698 | set_freezable(); |
Izik Eidus | 339aa62 | 2009-09-21 17:02:07 -0700 | [diff] [blame] | 1699 | set_user_nice(current, 5); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1700 | |
| 1701 | while (!kthread_should_stop()) { |
Hugh Dickins | 6e158384 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1702 | mutex_lock(&ksm_thread_mutex); |
| 1703 | if (ksmd_should_run()) |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1704 | ksm_do_scan(ksm_thread_pages_to_scan); |
Hugh Dickins | 6e158384 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1705 | mutex_unlock(&ksm_thread_mutex); |
| 1706 | |
Andrea Arcangeli | 878aee7 | 2011-01-13 15:47:10 -0800 | [diff] [blame] | 1707 | try_to_freeze(); |
| 1708 | |
Hugh Dickins | 6e158384 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1709 | if (ksmd_should_run()) { |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1710 | schedule_timeout_interruptible( |
| 1711 | msecs_to_jiffies(ksm_thread_sleep_millisecs)); |
| 1712 | } else { |
Andrea Arcangeli | 878aee7 | 2011-01-13 15:47:10 -0800 | [diff] [blame] | 1713 | wait_event_freezable(ksm_thread_wait, |
Hugh Dickins | 6e158384 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1714 | ksmd_should_run() || kthread_should_stop()); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1715 | } |
| 1716 | } |
| 1717 | return 0; |
| 1718 | } |
| 1719 | |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1720 | int ksm_madvise(struct vm_area_struct *vma, unsigned long start, |
| 1721 | unsigned long end, int advice, unsigned long *vm_flags) |
| 1722 | { |
| 1723 | struct mm_struct *mm = vma->vm_mm; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 1724 | int err; |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1725 | |
| 1726 | switch (advice) { |
| 1727 | case MADV_MERGEABLE: |
| 1728 | /* |
| 1729 | * Be somewhat over-protective for now! |
| 1730 | */ |
| 1731 | if (*vm_flags & (VM_MERGEABLE | VM_SHARED | VM_MAYSHARE | |
| 1732 | VM_PFNMAP | VM_IO | VM_DONTEXPAND | |
Konstantin Khlebnikov | 314e51b | 2012-10-08 16:29:02 -0700 | [diff] [blame] | 1733 | VM_HUGETLB | VM_NONLINEAR | VM_MIXEDMAP)) |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1734 | return 0; /* just ignore the advice */ |
| 1735 | |
Konstantin Khlebnikov | cc2383e | 2012-10-08 16:28:37 -0700 | [diff] [blame] | 1736 | #ifdef VM_SAO |
| 1737 | if (*vm_flags & VM_SAO) |
| 1738 | return 0; |
| 1739 | #endif |
| 1740 | |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 1741 | if (!test_bit(MMF_VM_MERGEABLE, &mm->flags)) { |
| 1742 | err = __ksm_enter(mm); |
| 1743 | if (err) |
| 1744 | return err; |
| 1745 | } |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1746 | |
| 1747 | *vm_flags |= VM_MERGEABLE; |
| 1748 | break; |
| 1749 | |
| 1750 | case MADV_UNMERGEABLE: |
| 1751 | if (!(*vm_flags & VM_MERGEABLE)) |
| 1752 | return 0; /* just ignore the advice */ |
| 1753 | |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 1754 | if (vma->anon_vma) { |
| 1755 | err = unmerge_ksm_pages(vma, start, end); |
| 1756 | if (err) |
| 1757 | return err; |
| 1758 | } |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1759 | |
| 1760 | *vm_flags &= ~VM_MERGEABLE; |
| 1761 | break; |
| 1762 | } |
| 1763 | |
| 1764 | return 0; |
| 1765 | } |
| 1766 | |
| 1767 | int __ksm_enter(struct mm_struct *mm) |
| 1768 | { |
Hugh Dickins | 6e158384 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1769 | struct mm_slot *mm_slot; |
| 1770 | int needs_wakeup; |
| 1771 | |
| 1772 | mm_slot = alloc_mm_slot(); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1773 | if (!mm_slot) |
| 1774 | return -ENOMEM; |
| 1775 | |
Hugh Dickins | 6e158384 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1776 | /* Check ksm_run too? Would need tighter locking */ |
| 1777 | needs_wakeup = list_empty(&ksm_mm_head.mm_list); |
| 1778 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1779 | spin_lock(&ksm_mmlist_lock); |
| 1780 | insert_to_mm_slots_hash(mm, mm_slot); |
| 1781 | /* |
Hugh Dickins | cbf86cf | 2013-02-22 16:35:08 -0800 | [diff] [blame] | 1782 | * When KSM_RUN_MERGE (or KSM_RUN_STOP), |
| 1783 | * insert just behind the scanning cursor, to let the area settle |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1784 | * down a little; when fork is followed by immediate exec, we don't |
| 1785 | * want ksmd to waste time setting up and tearing down an rmap_list. |
Hugh Dickins | cbf86cf | 2013-02-22 16:35:08 -0800 | [diff] [blame] | 1786 | * |
| 1787 | * But when KSM_RUN_UNMERGE, it's important to insert ahead of its |
| 1788 | * scanning cursor, otherwise KSM pages in newly forked mms will be |
| 1789 | * missed: then we might as well insert at the end of the list. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1790 | */ |
Hugh Dickins | cbf86cf | 2013-02-22 16:35:08 -0800 | [diff] [blame] | 1791 | if (ksm_run & KSM_RUN_UNMERGE) |
| 1792 | list_add_tail(&mm_slot->mm_list, &ksm_mm_head.mm_list); |
| 1793 | else |
| 1794 | list_add_tail(&mm_slot->mm_list, &ksm_scan.mm_slot->mm_list); |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1795 | spin_unlock(&ksm_mmlist_lock); |
| 1796 | |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1797 | set_bit(MMF_VM_MERGEABLE, &mm->flags); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1798 | atomic_inc(&mm->mm_count); |
Hugh Dickins | 6e158384 | 2009-09-21 17:02:14 -0700 | [diff] [blame] | 1799 | |
| 1800 | if (needs_wakeup) |
| 1801 | wake_up_interruptible(&ksm_thread_wait); |
| 1802 | |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1803 | return 0; |
| 1804 | } |
| 1805 | |
Andrea Arcangeli | 1c2fb7a | 2009-09-21 17:02:22 -0700 | [diff] [blame] | 1806 | void __ksm_exit(struct mm_struct *mm) |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1807 | { |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1808 | struct mm_slot *mm_slot; |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1809 | int easy_to_free = 0; |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1810 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1811 | /* |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1812 | * This process is exiting: if it's straightforward (as is the |
| 1813 | * case when ksmd was never running), free mm_slot immediately. |
| 1814 | * But if it's at the cursor or has rmap_items linked to it, use |
| 1815 | * mmap_sem to synchronize with any break_cows before pagetables |
| 1816 | * are freed, and leave the mm_slot on the list for ksmd to free. |
| 1817 | * Beware: ksm may already have noticed it exiting and freed the slot. |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1818 | */ |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1819 | |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1820 | spin_lock(&ksm_mmlist_lock); |
| 1821 | mm_slot = get_mm_slot(mm); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1822 | if (mm_slot && ksm_scan.mm_slot != mm_slot) { |
Hugh Dickins | 6514d51 | 2009-12-14 17:59:19 -0800 | [diff] [blame] | 1823 | if (!mm_slot->rmap_list) { |
Sasha Levin | 4ca3a69 | 2013-02-22 16:32:28 -0800 | [diff] [blame] | 1824 | hash_del(&mm_slot->link); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1825 | list_del(&mm_slot->mm_list); |
| 1826 | easy_to_free = 1; |
| 1827 | } else { |
| 1828 | list_move(&mm_slot->mm_list, |
| 1829 | &ksm_scan.mm_slot->mm_list); |
| 1830 | } |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1831 | } |
Hugh Dickins | cd551f9 | 2009-09-21 17:02:17 -0700 | [diff] [blame] | 1832 | spin_unlock(&ksm_mmlist_lock); |
| 1833 | |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1834 | if (easy_to_free) { |
| 1835 | free_mm_slot(mm_slot); |
| 1836 | clear_bit(MMF_VM_MERGEABLE, &mm->flags); |
| 1837 | mmdrop(mm); |
| 1838 | } else if (mm_slot) { |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1839 | down_write(&mm->mmap_sem); |
| 1840 | up_write(&mm->mmap_sem); |
Hugh Dickins | 9ba6929 | 2009-09-21 17:02:20 -0700 | [diff] [blame] | 1841 | } |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 1842 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 1843 | |
Hugh Dickins | cbf86cf | 2013-02-22 16:35:08 -0800 | [diff] [blame] | 1844 | struct page *ksm_might_need_to_copy(struct page *page, |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1845 | struct vm_area_struct *vma, unsigned long address) |
| 1846 | { |
Hugh Dickins | cbf86cf | 2013-02-22 16:35:08 -0800 | [diff] [blame] | 1847 | struct anon_vma *anon_vma = page_anon_vma(page); |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1848 | struct page *new_page; |
| 1849 | |
Hugh Dickins | cbf86cf | 2013-02-22 16:35:08 -0800 | [diff] [blame] | 1850 | if (PageKsm(page)) { |
| 1851 | if (page_stable_node(page) && |
| 1852 | !(ksm_run & KSM_RUN_UNMERGE)) |
| 1853 | return page; /* no need to copy it */ |
| 1854 | } else if (!anon_vma) { |
| 1855 | return page; /* no need to copy it */ |
| 1856 | } else if (anon_vma->root == vma->anon_vma->root && |
| 1857 | page->index == linear_page_index(vma, address)) { |
| 1858 | return page; /* still no need to copy it */ |
| 1859 | } |
| 1860 | if (!PageUptodate(page)) |
| 1861 | return page; /* let do_swap_page report the error */ |
| 1862 | |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1863 | new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); |
| 1864 | if (new_page) { |
| 1865 | copy_user_highpage(new_page, page, address, vma); |
| 1866 | |
| 1867 | SetPageDirty(new_page); |
| 1868 | __SetPageUptodate(new_page); |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1869 | __set_page_locked(new_page); |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1870 | } |
| 1871 | |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1872 | return new_page; |
| 1873 | } |
| 1874 | |
| 1875 | int page_referenced_ksm(struct page *page, struct mem_cgroup *memcg, |
| 1876 | unsigned long *vm_flags) |
| 1877 | { |
| 1878 | struct stable_node *stable_node; |
| 1879 | struct rmap_item *rmap_item; |
| 1880 | struct hlist_node *hlist; |
| 1881 | unsigned int mapcount = page_mapcount(page); |
| 1882 | int referenced = 0; |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1883 | int search_new_forks = 0; |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1884 | |
| 1885 | VM_BUG_ON(!PageKsm(page)); |
| 1886 | VM_BUG_ON(!PageLocked(page)); |
| 1887 | |
| 1888 | stable_node = page_stable_node(page); |
| 1889 | if (!stable_node) |
| 1890 | return 0; |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1891 | again: |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1892 | hlist_for_each_entry(rmap_item, hlist, &stable_node->hlist, hlist) { |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1893 | struct anon_vma *anon_vma = rmap_item->anon_vma; |
Rik van Riel | 5beb493 | 2010-03-05 13:42:07 -0800 | [diff] [blame] | 1894 | struct anon_vma_chain *vmac; |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1895 | struct vm_area_struct *vma; |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1896 | |
Hugh Dickins | b6b19f2 | 2012-12-19 17:44:29 -0800 | [diff] [blame] | 1897 | anon_vma_lock_read(anon_vma); |
Michel Lespinasse | bf181b9 | 2012-10-08 16:31:39 -0700 | [diff] [blame] | 1898 | anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root, |
| 1899 | 0, ULONG_MAX) { |
Rik van Riel | 5beb493 | 2010-03-05 13:42:07 -0800 | [diff] [blame] | 1900 | vma = vmac->vma; |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1901 | if (rmap_item->address < vma->vm_start || |
| 1902 | rmap_item->address >= vma->vm_end) |
| 1903 | continue; |
| 1904 | /* |
| 1905 | * Initially we examine only the vma which covers this |
| 1906 | * rmap_item; but later, if there is still work to do, |
| 1907 | * we examine covering vmas in other mms: in case they |
| 1908 | * were forked from the original since ksmd passed. |
| 1909 | */ |
| 1910 | if ((rmap_item->mm == vma->vm_mm) == search_new_forks) |
| 1911 | continue; |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1912 | |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1913 | if (memcg && !mm_match_cgroup(vma->vm_mm, memcg)) |
| 1914 | continue; |
| 1915 | |
| 1916 | referenced += page_referenced_one(page, vma, |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1917 | rmap_item->address, &mapcount, vm_flags); |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1918 | if (!search_new_forks || !mapcount) |
| 1919 | break; |
| 1920 | } |
Hugh Dickins | b6b19f2 | 2012-12-19 17:44:29 -0800 | [diff] [blame] | 1921 | anon_vma_unlock_read(anon_vma); |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1922 | if (!mapcount) |
| 1923 | goto out; |
| 1924 | } |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1925 | if (!search_new_forks++) |
| 1926 | goto again; |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1927 | out: |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1928 | return referenced; |
| 1929 | } |
| 1930 | |
| 1931 | int try_to_unmap_ksm(struct page *page, enum ttu_flags flags) |
| 1932 | { |
| 1933 | struct stable_node *stable_node; |
| 1934 | struct hlist_node *hlist; |
| 1935 | struct rmap_item *rmap_item; |
| 1936 | int ret = SWAP_AGAIN; |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1937 | int search_new_forks = 0; |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1938 | |
| 1939 | VM_BUG_ON(!PageKsm(page)); |
| 1940 | VM_BUG_ON(!PageLocked(page)); |
| 1941 | |
| 1942 | stable_node = page_stable_node(page); |
| 1943 | if (!stable_node) |
| 1944 | return SWAP_FAIL; |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1945 | again: |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1946 | hlist_for_each_entry(rmap_item, hlist, &stable_node->hlist, hlist) { |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1947 | struct anon_vma *anon_vma = rmap_item->anon_vma; |
Rik van Riel | 5beb493 | 2010-03-05 13:42:07 -0800 | [diff] [blame] | 1948 | struct anon_vma_chain *vmac; |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1949 | struct vm_area_struct *vma; |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1950 | |
Hugh Dickins | b6b19f2 | 2012-12-19 17:44:29 -0800 | [diff] [blame] | 1951 | anon_vma_lock_read(anon_vma); |
Michel Lespinasse | bf181b9 | 2012-10-08 16:31:39 -0700 | [diff] [blame] | 1952 | anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root, |
| 1953 | 0, ULONG_MAX) { |
Rik van Riel | 5beb493 | 2010-03-05 13:42:07 -0800 | [diff] [blame] | 1954 | vma = vmac->vma; |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1955 | if (rmap_item->address < vma->vm_start || |
| 1956 | rmap_item->address >= vma->vm_end) |
| 1957 | continue; |
| 1958 | /* |
| 1959 | * Initially we examine only the vma which covers this |
| 1960 | * rmap_item; but later, if there is still work to do, |
| 1961 | * we examine covering vmas in other mms: in case they |
| 1962 | * were forked from the original since ksmd passed. |
| 1963 | */ |
| 1964 | if ((rmap_item->mm == vma->vm_mm) == search_new_forks) |
| 1965 | continue; |
| 1966 | |
| 1967 | ret = try_to_unmap_one(page, vma, |
| 1968 | rmap_item->address, flags); |
| 1969 | if (ret != SWAP_AGAIN || !page_mapped(page)) { |
Hugh Dickins | b6b19f2 | 2012-12-19 17:44:29 -0800 | [diff] [blame] | 1970 | anon_vma_unlock_read(anon_vma); |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1971 | goto out; |
| 1972 | } |
| 1973 | } |
Hugh Dickins | b6b19f2 | 2012-12-19 17:44:29 -0800 | [diff] [blame] | 1974 | anon_vma_unlock_read(anon_vma); |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1975 | } |
Hugh Dickins | db114b8 | 2009-12-14 17:59:25 -0800 | [diff] [blame] | 1976 | if (!search_new_forks++) |
| 1977 | goto again; |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1978 | out: |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1979 | return ret; |
| 1980 | } |
| 1981 | |
Hugh Dickins | e9995ef | 2009-12-14 17:59:31 -0800 | [diff] [blame] | 1982 | #ifdef CONFIG_MIGRATION |
| 1983 | int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page *, |
| 1984 | struct vm_area_struct *, unsigned long, void *), void *arg) |
| 1985 | { |
| 1986 | struct stable_node *stable_node; |
| 1987 | struct hlist_node *hlist; |
| 1988 | struct rmap_item *rmap_item; |
| 1989 | int ret = SWAP_AGAIN; |
| 1990 | int search_new_forks = 0; |
| 1991 | |
| 1992 | VM_BUG_ON(!PageKsm(page)); |
| 1993 | VM_BUG_ON(!PageLocked(page)); |
| 1994 | |
| 1995 | stable_node = page_stable_node(page); |
| 1996 | if (!stable_node) |
| 1997 | return ret; |
| 1998 | again: |
| 1999 | hlist_for_each_entry(rmap_item, hlist, &stable_node->hlist, hlist) { |
| 2000 | struct anon_vma *anon_vma = rmap_item->anon_vma; |
Rik van Riel | 5beb493 | 2010-03-05 13:42:07 -0800 | [diff] [blame] | 2001 | struct anon_vma_chain *vmac; |
Hugh Dickins | e9995ef | 2009-12-14 17:59:31 -0800 | [diff] [blame] | 2002 | struct vm_area_struct *vma; |
| 2003 | |
Hugh Dickins | b6b19f2 | 2012-12-19 17:44:29 -0800 | [diff] [blame] | 2004 | anon_vma_lock_read(anon_vma); |
Michel Lespinasse | bf181b9 | 2012-10-08 16:31:39 -0700 | [diff] [blame] | 2005 | anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root, |
| 2006 | 0, ULONG_MAX) { |
Rik van Riel | 5beb493 | 2010-03-05 13:42:07 -0800 | [diff] [blame] | 2007 | vma = vmac->vma; |
Hugh Dickins | e9995ef | 2009-12-14 17:59:31 -0800 | [diff] [blame] | 2008 | if (rmap_item->address < vma->vm_start || |
| 2009 | rmap_item->address >= vma->vm_end) |
| 2010 | continue; |
| 2011 | /* |
| 2012 | * Initially we examine only the vma which covers this |
| 2013 | * rmap_item; but later, if there is still work to do, |
| 2014 | * we examine covering vmas in other mms: in case they |
| 2015 | * were forked from the original since ksmd passed. |
| 2016 | */ |
| 2017 | if ((rmap_item->mm == vma->vm_mm) == search_new_forks) |
| 2018 | continue; |
| 2019 | |
| 2020 | ret = rmap_one(page, vma, rmap_item->address, arg); |
| 2021 | if (ret != SWAP_AGAIN) { |
Hugh Dickins | b6b19f2 | 2012-12-19 17:44:29 -0800 | [diff] [blame] | 2022 | anon_vma_unlock_read(anon_vma); |
Hugh Dickins | e9995ef | 2009-12-14 17:59:31 -0800 | [diff] [blame] | 2023 | goto out; |
| 2024 | } |
| 2025 | } |
Hugh Dickins | b6b19f2 | 2012-12-19 17:44:29 -0800 | [diff] [blame] | 2026 | anon_vma_unlock_read(anon_vma); |
Hugh Dickins | e9995ef | 2009-12-14 17:59:31 -0800 | [diff] [blame] | 2027 | } |
| 2028 | if (!search_new_forks++) |
| 2029 | goto again; |
| 2030 | out: |
| 2031 | return ret; |
| 2032 | } |
| 2033 | |
| 2034 | void ksm_migrate_page(struct page *newpage, struct page *oldpage) |
| 2035 | { |
| 2036 | struct stable_node *stable_node; |
| 2037 | |
| 2038 | VM_BUG_ON(!PageLocked(oldpage)); |
| 2039 | VM_BUG_ON(!PageLocked(newpage)); |
| 2040 | VM_BUG_ON(newpage->mapping != oldpage->mapping); |
| 2041 | |
| 2042 | stable_node = page_stable_node(newpage); |
| 2043 | if (stable_node) { |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 2044 | VM_BUG_ON(stable_node->kpfn != page_to_pfn(oldpage)); |
| 2045 | stable_node->kpfn = page_to_pfn(newpage); |
Hugh Dickins | c8d6553 | 2013-02-22 16:35:10 -0800 | [diff] [blame] | 2046 | /* |
| 2047 | * newpage->mapping was set in advance; now we need smp_wmb() |
| 2048 | * to make sure that the new stable_node->kpfn is visible |
| 2049 | * to get_ksm_page() before it can see that oldpage->mapping |
| 2050 | * has gone stale (or that PageSwapCache has been cleared). |
| 2051 | */ |
| 2052 | smp_wmb(); |
| 2053 | set_page_stable_node(oldpage, NULL); |
Hugh Dickins | e9995ef | 2009-12-14 17:59:31 -0800 | [diff] [blame] | 2054 | } |
| 2055 | } |
| 2056 | #endif /* CONFIG_MIGRATION */ |
| 2057 | |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 2058 | #ifdef CONFIG_MEMORY_HOTREMOVE |
Hugh Dickins | ee0ea59 | 2013-02-22 16:35:05 -0800 | [diff] [blame] | 2059 | static void ksm_check_stable_tree(unsigned long start_pfn, |
| 2060 | unsigned long end_pfn) |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 2061 | { |
Hugh Dickins | ee0ea59 | 2013-02-22 16:35:05 -0800 | [diff] [blame] | 2062 | struct stable_node *stable_node; |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 2063 | struct list_head *this, *next; |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 2064 | struct rb_node *node; |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 2065 | int nid; |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 2066 | |
Hugh Dickins | ee0ea59 | 2013-02-22 16:35:05 -0800 | [diff] [blame] | 2067 | for (nid = 0; nid < nr_node_ids; nid++) { |
| 2068 | node = rb_first(&root_stable_tree[nid]); |
| 2069 | while (node) { |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 2070 | stable_node = rb_entry(node, struct stable_node, node); |
| 2071 | if (stable_node->kpfn >= start_pfn && |
Hugh Dickins | ee0ea59 | 2013-02-22 16:35:05 -0800 | [diff] [blame] | 2072 | stable_node->kpfn < end_pfn) { |
| 2073 | /* |
| 2074 | * Don't get_ksm_page, page has already gone: |
| 2075 | * which is why we keep kpfn instead of page* |
| 2076 | */ |
| 2077 | remove_node_from_stable_tree(stable_node); |
| 2078 | node = rb_first(&root_stable_tree[nid]); |
| 2079 | } else |
| 2080 | node = rb_next(node); |
| 2081 | cond_resched(); |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 2082 | } |
Hugh Dickins | ee0ea59 | 2013-02-22 16:35:05 -0800 | [diff] [blame] | 2083 | } |
Hugh Dickins | 4146d2d | 2013-02-22 16:35:11 -0800 | [diff] [blame^] | 2084 | list_for_each_safe(this, next, &migrate_nodes) { |
| 2085 | stable_node = list_entry(this, struct stable_node, list); |
| 2086 | if (stable_node->kpfn >= start_pfn && |
| 2087 | stable_node->kpfn < end_pfn) |
| 2088 | remove_node_from_stable_tree(stable_node); |
| 2089 | cond_resched(); |
| 2090 | } |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 2091 | } |
| 2092 | |
| 2093 | static int ksm_memory_callback(struct notifier_block *self, |
| 2094 | unsigned long action, void *arg) |
| 2095 | { |
| 2096 | struct memory_notify *mn = arg; |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 2097 | |
| 2098 | switch (action) { |
| 2099 | case MEM_GOING_OFFLINE: |
| 2100 | /* |
| 2101 | * Keep it very simple for now: just lock out ksmd and |
| 2102 | * MADV_UNMERGEABLE while any memory is going offline. |
KOSAKI Motohiro | a0b0f58 | 2010-12-02 14:31:20 -0800 | [diff] [blame] | 2103 | * mutex_lock_nested() is necessary because lockdep was alarmed |
| 2104 | * that here we take ksm_thread_mutex inside notifier chain |
| 2105 | * mutex, and later take notifier chain mutex inside |
| 2106 | * ksm_thread_mutex to unlock it. But that's safe because both |
| 2107 | * are inside mem_hotplug_mutex. |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 2108 | */ |
KOSAKI Motohiro | a0b0f58 | 2010-12-02 14:31:20 -0800 | [diff] [blame] | 2109 | mutex_lock_nested(&ksm_thread_mutex, SINGLE_DEPTH_NESTING); |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 2110 | break; |
| 2111 | |
| 2112 | case MEM_OFFLINE: |
| 2113 | /* |
| 2114 | * Most of the work is done by page migration; but there might |
| 2115 | * be a few stable_nodes left over, still pointing to struct |
Hugh Dickins | ee0ea59 | 2013-02-22 16:35:05 -0800 | [diff] [blame] | 2116 | * pages which have been offlined: prune those from the tree, |
| 2117 | * otherwise get_ksm_page() might later try to access a |
| 2118 | * non-existent struct page. |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 2119 | */ |
Hugh Dickins | ee0ea59 | 2013-02-22 16:35:05 -0800 | [diff] [blame] | 2120 | ksm_check_stable_tree(mn->start_pfn, |
| 2121 | mn->start_pfn + mn->nr_pages); |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 2122 | /* fallthrough */ |
| 2123 | |
| 2124 | case MEM_CANCEL_OFFLINE: |
| 2125 | mutex_unlock(&ksm_thread_mutex); |
| 2126 | break; |
| 2127 | } |
| 2128 | return NOTIFY_OK; |
| 2129 | } |
| 2130 | #endif /* CONFIG_MEMORY_HOTREMOVE */ |
| 2131 | |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 2132 | #ifdef CONFIG_SYSFS |
| 2133 | /* |
| 2134 | * This all compiles without CONFIG_SYSFS, but is a waste of space. |
| 2135 | */ |
| 2136 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2137 | #define KSM_ATTR_RO(_name) \ |
| 2138 | static struct kobj_attribute _name##_attr = __ATTR_RO(_name) |
| 2139 | #define KSM_ATTR(_name) \ |
| 2140 | static struct kobj_attribute _name##_attr = \ |
| 2141 | __ATTR(_name, 0644, _name##_show, _name##_store) |
| 2142 | |
| 2143 | static ssize_t sleep_millisecs_show(struct kobject *kobj, |
| 2144 | struct kobj_attribute *attr, char *buf) |
| 2145 | { |
| 2146 | return sprintf(buf, "%u\n", ksm_thread_sleep_millisecs); |
| 2147 | } |
| 2148 | |
| 2149 | static ssize_t sleep_millisecs_store(struct kobject *kobj, |
| 2150 | struct kobj_attribute *attr, |
| 2151 | const char *buf, size_t count) |
| 2152 | { |
| 2153 | unsigned long msecs; |
| 2154 | int err; |
| 2155 | |
| 2156 | err = strict_strtoul(buf, 10, &msecs); |
| 2157 | if (err || msecs > UINT_MAX) |
| 2158 | return -EINVAL; |
| 2159 | |
| 2160 | ksm_thread_sleep_millisecs = msecs; |
| 2161 | |
| 2162 | return count; |
| 2163 | } |
| 2164 | KSM_ATTR(sleep_millisecs); |
| 2165 | |
| 2166 | static ssize_t pages_to_scan_show(struct kobject *kobj, |
| 2167 | struct kobj_attribute *attr, char *buf) |
| 2168 | { |
| 2169 | return sprintf(buf, "%u\n", ksm_thread_pages_to_scan); |
| 2170 | } |
| 2171 | |
| 2172 | static ssize_t pages_to_scan_store(struct kobject *kobj, |
| 2173 | struct kobj_attribute *attr, |
| 2174 | const char *buf, size_t count) |
| 2175 | { |
| 2176 | int err; |
| 2177 | unsigned long nr_pages; |
| 2178 | |
| 2179 | err = strict_strtoul(buf, 10, &nr_pages); |
| 2180 | if (err || nr_pages > UINT_MAX) |
| 2181 | return -EINVAL; |
| 2182 | |
| 2183 | ksm_thread_pages_to_scan = nr_pages; |
| 2184 | |
| 2185 | return count; |
| 2186 | } |
| 2187 | KSM_ATTR(pages_to_scan); |
| 2188 | |
| 2189 | static ssize_t run_show(struct kobject *kobj, struct kobj_attribute *attr, |
| 2190 | char *buf) |
| 2191 | { |
| 2192 | return sprintf(buf, "%u\n", ksm_run); |
| 2193 | } |
| 2194 | |
| 2195 | static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr, |
| 2196 | const char *buf, size_t count) |
| 2197 | { |
| 2198 | int err; |
| 2199 | unsigned long flags; |
| 2200 | |
| 2201 | err = strict_strtoul(buf, 10, &flags); |
| 2202 | if (err || flags > UINT_MAX) |
| 2203 | return -EINVAL; |
| 2204 | if (flags > KSM_RUN_UNMERGE) |
| 2205 | return -EINVAL; |
| 2206 | |
| 2207 | /* |
| 2208 | * KSM_RUN_MERGE sets ksmd running, and 0 stops it running. |
| 2209 | * KSM_RUN_UNMERGE stops it running and unmerges all rmap_items, |
Hugh Dickins | d0f209f | 2009-12-14 17:59:34 -0800 | [diff] [blame] | 2210 | * breaking COW to free the pages_shared (but leaves mm_slots |
| 2211 | * on the list for when ksmd may be set running again). |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2212 | */ |
| 2213 | |
| 2214 | mutex_lock(&ksm_thread_mutex); |
| 2215 | if (ksm_run != flags) { |
| 2216 | ksm_run = flags; |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 2217 | if (flags & KSM_RUN_UNMERGE) { |
David Rientjes | e1e12d2 | 2012-12-11 16:02:56 -0800 | [diff] [blame] | 2218 | set_current_oom_origin(); |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 2219 | err = unmerge_and_remove_all_rmap_items(); |
David Rientjes | e1e12d2 | 2012-12-11 16:02:56 -0800 | [diff] [blame] | 2220 | clear_current_oom_origin(); |
Hugh Dickins | d952b79 | 2009-09-21 17:02:16 -0700 | [diff] [blame] | 2221 | if (err) { |
| 2222 | ksm_run = KSM_RUN_STOP; |
| 2223 | count = err; |
| 2224 | } |
| 2225 | } |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2226 | } |
| 2227 | mutex_unlock(&ksm_thread_mutex); |
| 2228 | |
| 2229 | if (flags & KSM_RUN_MERGE) |
| 2230 | wake_up_interruptible(&ksm_thread_wait); |
| 2231 | |
| 2232 | return count; |
| 2233 | } |
| 2234 | KSM_ATTR(run); |
| 2235 | |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 2236 | #ifdef CONFIG_NUMA |
| 2237 | static ssize_t merge_across_nodes_show(struct kobject *kobj, |
| 2238 | struct kobj_attribute *attr, char *buf) |
| 2239 | { |
| 2240 | return sprintf(buf, "%u\n", ksm_merge_across_nodes); |
| 2241 | } |
| 2242 | |
| 2243 | static ssize_t merge_across_nodes_store(struct kobject *kobj, |
| 2244 | struct kobj_attribute *attr, |
| 2245 | const char *buf, size_t count) |
| 2246 | { |
| 2247 | int err; |
| 2248 | unsigned long knob; |
| 2249 | |
| 2250 | err = kstrtoul(buf, 10, &knob); |
| 2251 | if (err) |
| 2252 | return err; |
| 2253 | if (knob > 1) |
| 2254 | return -EINVAL; |
| 2255 | |
| 2256 | mutex_lock(&ksm_thread_mutex); |
| 2257 | if (ksm_merge_across_nodes != knob) { |
Hugh Dickins | cbf86cf | 2013-02-22 16:35:08 -0800 | [diff] [blame] | 2258 | if (ksm_pages_shared || remove_all_stable_nodes()) |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 2259 | err = -EBUSY; |
| 2260 | else |
| 2261 | ksm_merge_across_nodes = knob; |
| 2262 | } |
| 2263 | mutex_unlock(&ksm_thread_mutex); |
| 2264 | |
| 2265 | return err ? err : count; |
| 2266 | } |
| 2267 | KSM_ATTR(merge_across_nodes); |
| 2268 | #endif |
| 2269 | |
Hugh Dickins | b402826 | 2009-09-21 17:02:09 -0700 | [diff] [blame] | 2270 | static ssize_t pages_shared_show(struct kobject *kobj, |
| 2271 | struct kobj_attribute *attr, char *buf) |
| 2272 | { |
| 2273 | return sprintf(buf, "%lu\n", ksm_pages_shared); |
| 2274 | } |
| 2275 | KSM_ATTR_RO(pages_shared); |
| 2276 | |
| 2277 | static ssize_t pages_sharing_show(struct kobject *kobj, |
| 2278 | struct kobj_attribute *attr, char *buf) |
| 2279 | { |
Hugh Dickins | e178dfd | 2009-09-21 17:02:10 -0700 | [diff] [blame] | 2280 | return sprintf(buf, "%lu\n", ksm_pages_sharing); |
Hugh Dickins | b402826 | 2009-09-21 17:02:09 -0700 | [diff] [blame] | 2281 | } |
| 2282 | KSM_ATTR_RO(pages_sharing); |
| 2283 | |
Hugh Dickins | 473b0ce | 2009-09-21 17:02:11 -0700 | [diff] [blame] | 2284 | static ssize_t pages_unshared_show(struct kobject *kobj, |
| 2285 | struct kobj_attribute *attr, char *buf) |
| 2286 | { |
| 2287 | return sprintf(buf, "%lu\n", ksm_pages_unshared); |
| 2288 | } |
| 2289 | KSM_ATTR_RO(pages_unshared); |
| 2290 | |
| 2291 | static ssize_t pages_volatile_show(struct kobject *kobj, |
| 2292 | struct kobj_attribute *attr, char *buf) |
| 2293 | { |
| 2294 | long ksm_pages_volatile; |
| 2295 | |
| 2296 | ksm_pages_volatile = ksm_rmap_items - ksm_pages_shared |
| 2297 | - ksm_pages_sharing - ksm_pages_unshared; |
| 2298 | /* |
| 2299 | * It was not worth any locking to calculate that statistic, |
| 2300 | * but it might therefore sometimes be negative: conceal that. |
| 2301 | */ |
| 2302 | if (ksm_pages_volatile < 0) |
| 2303 | ksm_pages_volatile = 0; |
| 2304 | return sprintf(buf, "%ld\n", ksm_pages_volatile); |
| 2305 | } |
| 2306 | KSM_ATTR_RO(pages_volatile); |
| 2307 | |
| 2308 | static ssize_t full_scans_show(struct kobject *kobj, |
| 2309 | struct kobj_attribute *attr, char *buf) |
| 2310 | { |
| 2311 | return sprintf(buf, "%lu\n", ksm_scan.seqnr); |
| 2312 | } |
| 2313 | KSM_ATTR_RO(full_scans); |
| 2314 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2315 | static struct attribute *ksm_attrs[] = { |
| 2316 | &sleep_millisecs_attr.attr, |
| 2317 | &pages_to_scan_attr.attr, |
| 2318 | &run_attr.attr, |
Hugh Dickins | b402826 | 2009-09-21 17:02:09 -0700 | [diff] [blame] | 2319 | &pages_shared_attr.attr, |
| 2320 | &pages_sharing_attr.attr, |
Hugh Dickins | 473b0ce | 2009-09-21 17:02:11 -0700 | [diff] [blame] | 2321 | &pages_unshared_attr.attr, |
| 2322 | &pages_volatile_attr.attr, |
| 2323 | &full_scans_attr.attr, |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 2324 | #ifdef CONFIG_NUMA |
| 2325 | &merge_across_nodes_attr.attr, |
| 2326 | #endif |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2327 | NULL, |
| 2328 | }; |
| 2329 | |
| 2330 | static struct attribute_group ksm_attr_group = { |
| 2331 | .attrs = ksm_attrs, |
| 2332 | .name = "ksm", |
| 2333 | }; |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 2334 | #endif /* CONFIG_SYSFS */ |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2335 | |
| 2336 | static int __init ksm_init(void) |
| 2337 | { |
| 2338 | struct task_struct *ksm_thread; |
| 2339 | int err; |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 2340 | int nid; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2341 | |
| 2342 | err = ksm_slab_init(); |
| 2343 | if (err) |
| 2344 | goto out; |
| 2345 | |
Petr Holasek | 90bd6fd | 2013-02-22 16:35:00 -0800 | [diff] [blame] | 2346 | for (nid = 0; nid < nr_node_ids; nid++) |
| 2347 | root_stable_tree[nid] = RB_ROOT; |
| 2348 | |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2349 | ksm_thread = kthread_run(ksm_scan_thread, NULL, "ksmd"); |
| 2350 | if (IS_ERR(ksm_thread)) { |
| 2351 | printk(KERN_ERR "ksm: creating kthread failed\n"); |
| 2352 | err = PTR_ERR(ksm_thread); |
Lai Jiangshan | d9f8984 | 2010-08-09 17:20:02 -0700 | [diff] [blame] | 2353 | goto out_free; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2354 | } |
| 2355 | |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 2356 | #ifdef CONFIG_SYSFS |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2357 | err = sysfs_create_group(mm_kobj, &ksm_attr_group); |
| 2358 | if (err) { |
| 2359 | printk(KERN_ERR "ksm: register sysfs failed\n"); |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 2360 | kthread_stop(ksm_thread); |
Lai Jiangshan | d9f8984 | 2010-08-09 17:20:02 -0700 | [diff] [blame] | 2361 | goto out_free; |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2362 | } |
Hugh Dickins | c73602a | 2009-10-07 16:32:22 -0700 | [diff] [blame] | 2363 | #else |
| 2364 | ksm_run = KSM_RUN_MERGE; /* no way for user to start it */ |
| 2365 | |
Hugh Dickins | 2ffd867 | 2009-09-21 17:02:23 -0700 | [diff] [blame] | 2366 | #endif /* CONFIG_SYSFS */ |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2367 | |
Hugh Dickins | 62b61f6 | 2009-12-14 17:59:33 -0800 | [diff] [blame] | 2368 | #ifdef CONFIG_MEMORY_HOTREMOVE |
| 2369 | /* |
| 2370 | * Choose a high priority since the callback takes ksm_thread_mutex: |
| 2371 | * later callbacks could only be taking locks which nest within that. |
| 2372 | */ |
| 2373 | hotplug_memory_notifier(ksm_memory_callback, 100); |
| 2374 | #endif |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2375 | return 0; |
| 2376 | |
Lai Jiangshan | d9f8984 | 2010-08-09 17:20:02 -0700 | [diff] [blame] | 2377 | out_free: |
Izik Eidus | 31dbd01 | 2009-09-21 17:02:03 -0700 | [diff] [blame] | 2378 | ksm_slab_free(); |
| 2379 | out: |
| 2380 | return err; |
| 2381 | } |
| 2382 | module_init(ksm_init) |