Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/mm/swapfile.c |
| 3 | * |
| 4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds |
| 5 | * Swap reorganised 29.12.95, Stephen Tweedie |
| 6 | */ |
| 7 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 8 | #include <linux/mm.h> |
| 9 | #include <linux/hugetlb.h> |
| 10 | #include <linux/mman.h> |
| 11 | #include <linux/slab.h> |
| 12 | #include <linux/kernel_stat.h> |
| 13 | #include <linux/swap.h> |
| 14 | #include <linux/vmalloc.h> |
| 15 | #include <linux/pagemap.h> |
| 16 | #include <linux/namei.h> |
| 17 | #include <linux/shm.h> |
| 18 | #include <linux/blkdev.h> |
Hugh Dickins | 20137a4 | 2009-01-06 14:39:54 -0800 | [diff] [blame] | 19 | #include <linux/random.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 20 | #include <linux/writeback.h> |
| 21 | #include <linux/proc_fs.h> |
| 22 | #include <linux/seq_file.h> |
| 23 | #include <linux/init.h> |
| 24 | #include <linux/module.h> |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 25 | #include <linux/ksm.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 26 | #include <linux/rmap.h> |
| 27 | #include <linux/security.h> |
| 28 | #include <linux/backing-dev.h> |
Ingo Molnar | fc0abb1 | 2006-01-18 17:42:33 -0800 | [diff] [blame] | 29 | #include <linux/mutex.h> |
Randy.Dunlap | c59ede7 | 2006-01-11 12:17:46 -0800 | [diff] [blame] | 30 | #include <linux/capability.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | #include <linux/syscalls.h> |
Balbir Singh | 8a9f3cc | 2008-02-07 00:13:53 -0800 | [diff] [blame] | 32 | #include <linux/memcontrol.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 33 | |
| 34 | #include <asm/pgtable.h> |
| 35 | #include <asm/tlbflush.h> |
| 36 | #include <linux/swapops.h> |
KAMEZAWA Hiroyuki | 27a7faa | 2009-01-07 18:07:58 -0800 | [diff] [blame] | 37 | #include <linux/page_cgroup.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 38 | |
Hugh Dickins | 570a335b | 2009-12-14 17:58:46 -0800 | [diff] [blame] | 39 | static bool swap_count_continued(struct swap_info_struct *, pgoff_t, |
| 40 | unsigned char); |
| 41 | static void free_swap_count_continuations(struct swap_info_struct *); |
Lee Schermerhorn | d4906e1 | 2009-12-14 17:58:49 -0800 | [diff] [blame] | 42 | static sector_t map_swap_entry(swp_entry_t, struct block_device**); |
Hugh Dickins | 570a335b | 2009-12-14 17:58:46 -0800 | [diff] [blame] | 43 | |
Adrian Bunk | 7c363b8 | 2008-07-25 19:46:24 -0700 | [diff] [blame] | 44 | static DEFINE_SPINLOCK(swap_lock); |
| 45 | static unsigned int nr_swapfiles; |
Hugh Dickins | b962716 | 2009-01-06 14:39:41 -0800 | [diff] [blame] | 46 | long nr_swap_pages; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 47 | long total_swap_pages; |
Hugh Dickins | 78ecba0 | 2008-07-23 21:28:23 -0700 | [diff] [blame] | 48 | static int least_priority; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 49 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 50 | static const char Bad_file[] = "Bad swap file entry "; |
| 51 | static const char Unused_file[] = "Unused swap file entry "; |
| 52 | static const char Bad_offset[] = "Bad swap offset entry "; |
| 53 | static const char Unused_offset[] = "Unused swap offset entry "; |
| 54 | |
Adrian Bunk | 7c363b8 | 2008-07-25 19:46:24 -0700 | [diff] [blame] | 55 | static struct swap_list_t swap_list = {-1, -1}; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 56 | |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 57 | static struct swap_info_struct *swap_info[MAX_SWAPFILES]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 58 | |
Ingo Molnar | fc0abb1 | 2006-01-18 17:42:33 -0800 | [diff] [blame] | 59 | static DEFINE_MUTEX(swapon_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 60 | |
Hugh Dickins | 8d69aae | 2009-12-14 17:58:45 -0800 | [diff] [blame] | 61 | static inline unsigned char swap_count(unsigned char ent) |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 62 | { |
Hugh Dickins | 570a335b | 2009-12-14 17:58:46 -0800 | [diff] [blame] | 63 | return ent & ~SWAP_HAS_CACHE; /* may include SWAP_HAS_CONT flag */ |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 64 | } |
| 65 | |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 66 | /* returns 1 if swap entry is freed */ |
KAMEZAWA Hiroyuki | c9e4441 | 2009-06-16 15:32:54 -0700 | [diff] [blame] | 67 | static int |
| 68 | __try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset) |
| 69 | { |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 70 | swp_entry_t entry = swp_entry(si->type, offset); |
KAMEZAWA Hiroyuki | c9e4441 | 2009-06-16 15:32:54 -0700 | [diff] [blame] | 71 | struct page *page; |
| 72 | int ret = 0; |
| 73 | |
| 74 | page = find_get_page(&swapper_space, entry.val); |
| 75 | if (!page) |
| 76 | return 0; |
| 77 | /* |
| 78 | * This function is called from scan_swap_map() and it's called |
| 79 | * by vmscan.c at reclaiming pages. So, we hold a lock on a page, here. |
| 80 | * We have to use trylock for avoiding deadlock. This is a special |
| 81 | * case and you should use try_to_free_swap() with explicit lock_page() |
| 82 | * in usual operations. |
| 83 | */ |
| 84 | if (trylock_page(page)) { |
| 85 | ret = try_to_free_swap(page); |
| 86 | unlock_page(page); |
| 87 | } |
| 88 | page_cache_release(page); |
| 89 | return ret; |
| 90 | } |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 91 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 92 | /* |
| 93 | * We need this because the bdev->unplug_fn can sleep and we cannot |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 94 | * hold swap_lock while calling the unplug_fn. And swap_lock |
Ingo Molnar | fc0abb1 | 2006-01-18 17:42:33 -0800 | [diff] [blame] | 95 | * cannot be turned into a mutex. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 96 | */ |
| 97 | static DECLARE_RWSEM(swap_unplug_sem); |
| 98 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 99 | void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page) |
| 100 | { |
| 101 | swp_entry_t entry; |
| 102 | |
| 103 | down_read(&swap_unplug_sem); |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 104 | entry.val = page_private(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 105 | if (PageSwapCache(page)) { |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 106 | struct block_device *bdev = swap_info[swp_type(entry)]->bdev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 107 | struct backing_dev_info *bdi; |
| 108 | |
| 109 | /* |
| 110 | * If the page is removed from swapcache from under us (with a |
| 111 | * racy try_to_unuse/swapoff) we need an additional reference |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 112 | * count to avoid reading garbage from page_private(page) above. |
| 113 | * If the WARN_ON triggers during a swapoff it maybe the race |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 114 | * condition and it's harmless. However if it triggers without |
| 115 | * swapoff it signals a problem. |
| 116 | */ |
| 117 | WARN_ON(page_count(page) <= 1); |
| 118 | |
| 119 | bdi = bdev->bd_inode->i_mapping->backing_dev_info; |
McMullan, Jason | ba32311 | 2005-05-16 21:53:40 -0700 | [diff] [blame] | 120 | blk_run_backing_dev(bdi, page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 121 | } |
| 122 | up_read(&swap_unplug_sem); |
| 123 | } |
| 124 | |
Hugh Dickins | 6a6ba83 | 2009-01-06 14:39:51 -0800 | [diff] [blame] | 125 | /* |
| 126 | * swapon tell device that all the old swap contents can be discarded, |
| 127 | * to allow the swap device to optimize its wear-levelling. |
| 128 | */ |
| 129 | static int discard_swap(struct swap_info_struct *si) |
| 130 | { |
| 131 | struct swap_extent *se; |
Hugh Dickins | 9625a5f | 2009-12-14 17:58:42 -0800 | [diff] [blame] | 132 | sector_t start_block; |
| 133 | sector_t nr_blocks; |
Hugh Dickins | 6a6ba83 | 2009-01-06 14:39:51 -0800 | [diff] [blame] | 134 | int err = 0; |
| 135 | |
Hugh Dickins | 9625a5f | 2009-12-14 17:58:42 -0800 | [diff] [blame] | 136 | /* Do not discard the swap header page! */ |
| 137 | se = &si->first_swap_extent; |
| 138 | start_block = (se->start_block + 1) << (PAGE_SHIFT - 9); |
| 139 | nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9); |
| 140 | if (nr_blocks) { |
| 141 | err = blkdev_issue_discard(si->bdev, start_block, |
Christoph Hellwig | dd3932e | 2010-09-16 20:51:46 +0200 | [diff] [blame] | 142 | nr_blocks, GFP_KERNEL, 0); |
Hugh Dickins | 9625a5f | 2009-12-14 17:58:42 -0800 | [diff] [blame] | 143 | if (err) |
| 144 | return err; |
| 145 | cond_resched(); |
| 146 | } |
Hugh Dickins | 6a6ba83 | 2009-01-06 14:39:51 -0800 | [diff] [blame] | 147 | |
Hugh Dickins | 9625a5f | 2009-12-14 17:58:42 -0800 | [diff] [blame] | 148 | list_for_each_entry(se, &si->first_swap_extent.list, list) { |
| 149 | start_block = se->start_block << (PAGE_SHIFT - 9); |
| 150 | nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); |
Hugh Dickins | 6a6ba83 | 2009-01-06 14:39:51 -0800 | [diff] [blame] | 151 | |
| 152 | err = blkdev_issue_discard(si->bdev, start_block, |
Christoph Hellwig | dd3932e | 2010-09-16 20:51:46 +0200 | [diff] [blame] | 153 | nr_blocks, GFP_KERNEL, 0); |
Hugh Dickins | 6a6ba83 | 2009-01-06 14:39:51 -0800 | [diff] [blame] | 154 | if (err) |
| 155 | break; |
| 156 | |
| 157 | cond_resched(); |
| 158 | } |
| 159 | return err; /* That will often be -EOPNOTSUPP */ |
| 160 | } |
| 161 | |
Hugh Dickins | 7992fde | 2009-01-06 14:39:53 -0800 | [diff] [blame] | 162 | /* |
| 163 | * swap allocation tell device that a cluster of swap can now be discarded, |
| 164 | * to allow the swap device to optimize its wear-levelling. |
| 165 | */ |
| 166 | static void discard_swap_cluster(struct swap_info_struct *si, |
| 167 | pgoff_t start_page, pgoff_t nr_pages) |
| 168 | { |
| 169 | struct swap_extent *se = si->curr_swap_extent; |
| 170 | int found_extent = 0; |
| 171 | |
| 172 | while (nr_pages) { |
| 173 | struct list_head *lh; |
| 174 | |
| 175 | if (se->start_page <= start_page && |
| 176 | start_page < se->start_page + se->nr_pages) { |
| 177 | pgoff_t offset = start_page - se->start_page; |
| 178 | sector_t start_block = se->start_block + offset; |
Hugh Dickins | 858a2990 | 2009-01-06 14:39:56 -0800 | [diff] [blame] | 179 | sector_t nr_blocks = se->nr_pages - offset; |
Hugh Dickins | 7992fde | 2009-01-06 14:39:53 -0800 | [diff] [blame] | 180 | |
| 181 | if (nr_blocks > nr_pages) |
| 182 | nr_blocks = nr_pages; |
| 183 | start_page += nr_blocks; |
| 184 | nr_pages -= nr_blocks; |
| 185 | |
| 186 | if (!found_extent++) |
| 187 | si->curr_swap_extent = se; |
| 188 | |
| 189 | start_block <<= PAGE_SHIFT - 9; |
| 190 | nr_blocks <<= PAGE_SHIFT - 9; |
| 191 | if (blkdev_issue_discard(si->bdev, start_block, |
Christoph Hellwig | dd3932e | 2010-09-16 20:51:46 +0200 | [diff] [blame] | 192 | nr_blocks, GFP_NOIO, 0)) |
Hugh Dickins | 7992fde | 2009-01-06 14:39:53 -0800 | [diff] [blame] | 193 | break; |
| 194 | } |
| 195 | |
| 196 | lh = se->list.next; |
Hugh Dickins | 7992fde | 2009-01-06 14:39:53 -0800 | [diff] [blame] | 197 | se = list_entry(lh, struct swap_extent, list); |
| 198 | } |
| 199 | } |
| 200 | |
| 201 | static int wait_for_discard(void *word) |
| 202 | { |
| 203 | schedule(); |
| 204 | return 0; |
| 205 | } |
| 206 | |
Hugh Dickins | 048c27f | 2005-09-03 15:54:40 -0700 | [diff] [blame] | 207 | #define SWAPFILE_CLUSTER 256 |
| 208 | #define LATENCY_LIMIT 256 |
| 209 | |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 210 | static inline unsigned long scan_swap_map(struct swap_info_struct *si, |
Hugh Dickins | 8d69aae | 2009-12-14 17:58:45 -0800 | [diff] [blame] | 211 | unsigned char usage) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 212 | { |
Hugh Dickins | ebebbbe | 2009-01-06 14:39:50 -0800 | [diff] [blame] | 213 | unsigned long offset; |
Hugh Dickins | c60aa17 | 2009-01-06 14:39:55 -0800 | [diff] [blame] | 214 | unsigned long scan_base; |
Hugh Dickins | 7992fde | 2009-01-06 14:39:53 -0800 | [diff] [blame] | 215 | unsigned long last_in_cluster = 0; |
Hugh Dickins | 048c27f | 2005-09-03 15:54:40 -0700 | [diff] [blame] | 216 | int latency_ration = LATENCY_LIMIT; |
Hugh Dickins | 7992fde | 2009-01-06 14:39:53 -0800 | [diff] [blame] | 217 | int found_free_cluster = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 218 | |
Hugh Dickins | 886bb7e | 2009-01-06 14:39:48 -0800 | [diff] [blame] | 219 | /* |
Hugh Dickins | 7dfad41 | 2005-09-03 15:54:38 -0700 | [diff] [blame] | 220 | * We try to cluster swap pages by allocating them sequentially |
| 221 | * in swap. Once we've allocated SWAPFILE_CLUSTER pages this |
| 222 | * way, however, we resort to first-free allocation, starting |
| 223 | * a new cluster. This prevents us from scattering swap pages |
| 224 | * all over the entire swap partition, so that we reduce |
| 225 | * overall disk seek times between swap pages. -- sct |
| 226 | * But we do now try to find an empty cluster. -Andrea |
Hugh Dickins | c60aa17 | 2009-01-06 14:39:55 -0800 | [diff] [blame] | 227 | * And we let swap pages go all over an SSD partition. Hugh |
Hugh Dickins | 7dfad41 | 2005-09-03 15:54:38 -0700 | [diff] [blame] | 228 | */ |
| 229 | |
Hugh Dickins | 52b7efdb | 2005-09-03 15:54:39 -0700 | [diff] [blame] | 230 | si->flags += SWP_SCANNING; |
Hugh Dickins | c60aa17 | 2009-01-06 14:39:55 -0800 | [diff] [blame] | 231 | scan_base = offset = si->cluster_next; |
Hugh Dickins | ebebbbe | 2009-01-06 14:39:50 -0800 | [diff] [blame] | 232 | |
| 233 | if (unlikely(!si->cluster_nr--)) { |
| 234 | if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { |
| 235 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
| 236 | goto checks; |
| 237 | } |
Hugh Dickins | 7992fde | 2009-01-06 14:39:53 -0800 | [diff] [blame] | 238 | if (si->flags & SWP_DISCARDABLE) { |
| 239 | /* |
| 240 | * Start range check on racing allocations, in case |
| 241 | * they overlap the cluster we eventually decide on |
| 242 | * (we scan without swap_lock to allow preemption). |
| 243 | * It's hardly conceivable that cluster_nr could be |
| 244 | * wrapped during our scan, but don't depend on it. |
| 245 | */ |
| 246 | if (si->lowest_alloc) |
| 247 | goto checks; |
| 248 | si->lowest_alloc = si->max; |
| 249 | si->highest_alloc = 0; |
| 250 | } |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 251 | spin_unlock(&swap_lock); |
Hugh Dickins | 7dfad41 | 2005-09-03 15:54:38 -0700 | [diff] [blame] | 252 | |
Hugh Dickins | c60aa17 | 2009-01-06 14:39:55 -0800 | [diff] [blame] | 253 | /* |
| 254 | * If seek is expensive, start searching for new cluster from |
| 255 | * start of partition, to minimize the span of allocated swap. |
| 256 | * But if seek is cheap, search from our current position, so |
| 257 | * that swap is allocated from all over the partition: if the |
| 258 | * Flash Translation Layer only remaps within limited zones, |
| 259 | * we don't want to wear out the first zone too quickly. |
| 260 | */ |
| 261 | if (!(si->flags & SWP_SOLIDSTATE)) |
| 262 | scan_base = offset = si->lowest_bit; |
Hugh Dickins | 7dfad41 | 2005-09-03 15:54:38 -0700 | [diff] [blame] | 263 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
| 264 | |
| 265 | /* Locate the first empty (unaligned) cluster */ |
| 266 | for (; last_in_cluster <= si->highest_bit; offset++) { |
| 267 | if (si->swap_map[offset]) |
| 268 | last_in_cluster = offset + SWAPFILE_CLUSTER; |
| 269 | else if (offset == last_in_cluster) { |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 270 | spin_lock(&swap_lock); |
Hugh Dickins | ebebbbe | 2009-01-06 14:39:50 -0800 | [diff] [blame] | 271 | offset -= SWAPFILE_CLUSTER - 1; |
| 272 | si->cluster_next = offset; |
| 273 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
Hugh Dickins | 7992fde | 2009-01-06 14:39:53 -0800 | [diff] [blame] | 274 | found_free_cluster = 1; |
Hugh Dickins | ebebbbe | 2009-01-06 14:39:50 -0800 | [diff] [blame] | 275 | goto checks; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 276 | } |
Hugh Dickins | 048c27f | 2005-09-03 15:54:40 -0700 | [diff] [blame] | 277 | if (unlikely(--latency_ration < 0)) { |
| 278 | cond_resched(); |
| 279 | latency_ration = LATENCY_LIMIT; |
| 280 | } |
Hugh Dickins | 7dfad41 | 2005-09-03 15:54:38 -0700 | [diff] [blame] | 281 | } |
Hugh Dickins | ebebbbe | 2009-01-06 14:39:50 -0800 | [diff] [blame] | 282 | |
| 283 | offset = si->lowest_bit; |
Hugh Dickins | c60aa17 | 2009-01-06 14:39:55 -0800 | [diff] [blame] | 284 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
| 285 | |
| 286 | /* Locate the first empty (unaligned) cluster */ |
| 287 | for (; last_in_cluster < scan_base; offset++) { |
| 288 | if (si->swap_map[offset]) |
| 289 | last_in_cluster = offset + SWAPFILE_CLUSTER; |
| 290 | else if (offset == last_in_cluster) { |
| 291 | spin_lock(&swap_lock); |
| 292 | offset -= SWAPFILE_CLUSTER - 1; |
| 293 | si->cluster_next = offset; |
| 294 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
| 295 | found_free_cluster = 1; |
| 296 | goto checks; |
| 297 | } |
| 298 | if (unlikely(--latency_ration < 0)) { |
| 299 | cond_resched(); |
| 300 | latency_ration = LATENCY_LIMIT; |
| 301 | } |
| 302 | } |
| 303 | |
| 304 | offset = scan_base; |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 305 | spin_lock(&swap_lock); |
Hugh Dickins | ebebbbe | 2009-01-06 14:39:50 -0800 | [diff] [blame] | 306 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
Hugh Dickins | 7992fde | 2009-01-06 14:39:53 -0800 | [diff] [blame] | 307 | si->lowest_alloc = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 308 | } |
Hugh Dickins | 7dfad41 | 2005-09-03 15:54:38 -0700 | [diff] [blame] | 309 | |
Hugh Dickins | ebebbbe | 2009-01-06 14:39:50 -0800 | [diff] [blame] | 310 | checks: |
| 311 | if (!(si->flags & SWP_WRITEOK)) |
Hugh Dickins | 52b7efdb | 2005-09-03 15:54:39 -0700 | [diff] [blame] | 312 | goto no_page; |
Hugh Dickins | 7dfad41 | 2005-09-03 15:54:38 -0700 | [diff] [blame] | 313 | if (!si->highest_bit) |
| 314 | goto no_page; |
Hugh Dickins | ebebbbe | 2009-01-06 14:39:50 -0800 | [diff] [blame] | 315 | if (offset > si->highest_bit) |
Hugh Dickins | c60aa17 | 2009-01-06 14:39:55 -0800 | [diff] [blame] | 316 | scan_base = offset = si->lowest_bit; |
KAMEZAWA Hiroyuki | c9e4441 | 2009-06-16 15:32:54 -0700 | [diff] [blame] | 317 | |
Hugh Dickins | b73d7fc | 2010-09-09 16:38:09 -0700 | [diff] [blame] | 318 | /* reuse swap entry of cache-only swap if not busy. */ |
| 319 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
KAMEZAWA Hiroyuki | c9e4441 | 2009-06-16 15:32:54 -0700 | [diff] [blame] | 320 | int swap_was_freed; |
| 321 | spin_unlock(&swap_lock); |
| 322 | swap_was_freed = __try_to_reclaim_swap(si, offset); |
| 323 | spin_lock(&swap_lock); |
| 324 | /* entry was freed successfully, try to use this again */ |
| 325 | if (swap_was_freed) |
| 326 | goto checks; |
| 327 | goto scan; /* check next one */ |
| 328 | } |
| 329 | |
Hugh Dickins | ebebbbe | 2009-01-06 14:39:50 -0800 | [diff] [blame] | 330 | if (si->swap_map[offset]) |
| 331 | goto scan; |
Hugh Dickins | 7dfad41 | 2005-09-03 15:54:38 -0700 | [diff] [blame] | 332 | |
Hugh Dickins | ebebbbe | 2009-01-06 14:39:50 -0800 | [diff] [blame] | 333 | if (offset == si->lowest_bit) |
| 334 | si->lowest_bit++; |
| 335 | if (offset == si->highest_bit) |
| 336 | si->highest_bit--; |
| 337 | si->inuse_pages++; |
| 338 | if (si->inuse_pages == si->pages) { |
| 339 | si->lowest_bit = si->max; |
| 340 | si->highest_bit = 0; |
| 341 | } |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 342 | si->swap_map[offset] = usage; |
Hugh Dickins | ebebbbe | 2009-01-06 14:39:50 -0800 | [diff] [blame] | 343 | si->cluster_next = offset + 1; |
| 344 | si->flags -= SWP_SCANNING; |
Hugh Dickins | 7992fde | 2009-01-06 14:39:53 -0800 | [diff] [blame] | 345 | |
| 346 | if (si->lowest_alloc) { |
| 347 | /* |
| 348 | * Only set when SWP_DISCARDABLE, and there's a scan |
| 349 | * for a free cluster in progress or just completed. |
| 350 | */ |
| 351 | if (found_free_cluster) { |
| 352 | /* |
| 353 | * To optimize wear-levelling, discard the |
| 354 | * old data of the cluster, taking care not to |
| 355 | * discard any of its pages that have already |
| 356 | * been allocated by racing tasks (offset has |
| 357 | * already stepped over any at the beginning). |
| 358 | */ |
| 359 | if (offset < si->highest_alloc && |
| 360 | si->lowest_alloc <= last_in_cluster) |
| 361 | last_in_cluster = si->lowest_alloc - 1; |
| 362 | si->flags |= SWP_DISCARDING; |
| 363 | spin_unlock(&swap_lock); |
| 364 | |
| 365 | if (offset < last_in_cluster) |
| 366 | discard_swap_cluster(si, offset, |
| 367 | last_in_cluster - offset + 1); |
| 368 | |
| 369 | spin_lock(&swap_lock); |
| 370 | si->lowest_alloc = 0; |
| 371 | si->flags &= ~SWP_DISCARDING; |
| 372 | |
| 373 | smp_mb(); /* wake_up_bit advises this */ |
| 374 | wake_up_bit(&si->flags, ilog2(SWP_DISCARDING)); |
| 375 | |
| 376 | } else if (si->flags & SWP_DISCARDING) { |
| 377 | /* |
| 378 | * Delay using pages allocated by racing tasks |
| 379 | * until the whole discard has been issued. We |
| 380 | * could defer that delay until swap_writepage, |
| 381 | * but it's easier to keep this self-contained. |
| 382 | */ |
| 383 | spin_unlock(&swap_lock); |
| 384 | wait_on_bit(&si->flags, ilog2(SWP_DISCARDING), |
| 385 | wait_for_discard, TASK_UNINTERRUPTIBLE); |
| 386 | spin_lock(&swap_lock); |
| 387 | } else { |
| 388 | /* |
| 389 | * Note pages allocated by racing tasks while |
| 390 | * scan for a free cluster is in progress, so |
| 391 | * that its final discard can exclude them. |
| 392 | */ |
| 393 | if (offset < si->lowest_alloc) |
| 394 | si->lowest_alloc = offset; |
| 395 | if (offset > si->highest_alloc) |
| 396 | si->highest_alloc = offset; |
| 397 | } |
| 398 | } |
Hugh Dickins | ebebbbe | 2009-01-06 14:39:50 -0800 | [diff] [blame] | 399 | return offset; |
| 400 | |
| 401 | scan: |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 402 | spin_unlock(&swap_lock); |
Hugh Dickins | 7dfad41 | 2005-09-03 15:54:38 -0700 | [diff] [blame] | 403 | while (++offset <= si->highest_bit) { |
Hugh Dickins | 52b7efdb | 2005-09-03 15:54:39 -0700 | [diff] [blame] | 404 | if (!si->swap_map[offset]) { |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 405 | spin_lock(&swap_lock); |
Hugh Dickins | 52b7efdb | 2005-09-03 15:54:39 -0700 | [diff] [blame] | 406 | goto checks; |
| 407 | } |
KAMEZAWA Hiroyuki | c9e4441 | 2009-06-16 15:32:54 -0700 | [diff] [blame] | 408 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
| 409 | spin_lock(&swap_lock); |
| 410 | goto checks; |
| 411 | } |
Hugh Dickins | 048c27f | 2005-09-03 15:54:40 -0700 | [diff] [blame] | 412 | if (unlikely(--latency_ration < 0)) { |
| 413 | cond_resched(); |
| 414 | latency_ration = LATENCY_LIMIT; |
| 415 | } |
Hugh Dickins | 7dfad41 | 2005-09-03 15:54:38 -0700 | [diff] [blame] | 416 | } |
Hugh Dickins | c60aa17 | 2009-01-06 14:39:55 -0800 | [diff] [blame] | 417 | offset = si->lowest_bit; |
| 418 | while (++offset < scan_base) { |
| 419 | if (!si->swap_map[offset]) { |
| 420 | spin_lock(&swap_lock); |
| 421 | goto checks; |
| 422 | } |
KAMEZAWA Hiroyuki | c9e4441 | 2009-06-16 15:32:54 -0700 | [diff] [blame] | 423 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
| 424 | spin_lock(&swap_lock); |
| 425 | goto checks; |
| 426 | } |
Hugh Dickins | c60aa17 | 2009-01-06 14:39:55 -0800 | [diff] [blame] | 427 | if (unlikely(--latency_ration < 0)) { |
| 428 | cond_resched(); |
| 429 | latency_ration = LATENCY_LIMIT; |
| 430 | } |
| 431 | } |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 432 | spin_lock(&swap_lock); |
Hugh Dickins | 7dfad41 | 2005-09-03 15:54:38 -0700 | [diff] [blame] | 433 | |
| 434 | no_page: |
Hugh Dickins | 52b7efdb | 2005-09-03 15:54:39 -0700 | [diff] [blame] | 435 | si->flags -= SWP_SCANNING; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 436 | return 0; |
| 437 | } |
| 438 | |
| 439 | swp_entry_t get_swap_page(void) |
| 440 | { |
Hugh Dickins | fb4f88d | 2005-09-03 15:54:37 -0700 | [diff] [blame] | 441 | struct swap_info_struct *si; |
| 442 | pgoff_t offset; |
| 443 | int type, next; |
| 444 | int wrapped = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 445 | |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 446 | spin_lock(&swap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 447 | if (nr_swap_pages <= 0) |
Hugh Dickins | fb4f88d | 2005-09-03 15:54:37 -0700 | [diff] [blame] | 448 | goto noswap; |
| 449 | nr_swap_pages--; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 450 | |
Hugh Dickins | fb4f88d | 2005-09-03 15:54:37 -0700 | [diff] [blame] | 451 | for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) { |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 452 | si = swap_info[type]; |
Hugh Dickins | fb4f88d | 2005-09-03 15:54:37 -0700 | [diff] [blame] | 453 | next = si->next; |
| 454 | if (next < 0 || |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 455 | (!wrapped && si->prio != swap_info[next]->prio)) { |
Hugh Dickins | fb4f88d | 2005-09-03 15:54:37 -0700 | [diff] [blame] | 456 | next = swap_list.head; |
| 457 | wrapped++; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 458 | } |
Hugh Dickins | fb4f88d | 2005-09-03 15:54:37 -0700 | [diff] [blame] | 459 | |
| 460 | if (!si->highest_bit) |
| 461 | continue; |
| 462 | if (!(si->flags & SWP_WRITEOK)) |
| 463 | continue; |
| 464 | |
| 465 | swap_list.next = next; |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 466 | /* This is called for allocating swap entry for cache */ |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 467 | offset = scan_swap_map(si, SWAP_HAS_CACHE); |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 468 | if (offset) { |
| 469 | spin_unlock(&swap_lock); |
Hugh Dickins | fb4f88d | 2005-09-03 15:54:37 -0700 | [diff] [blame] | 470 | return swp_entry(type, offset); |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 471 | } |
Hugh Dickins | fb4f88d | 2005-09-03 15:54:37 -0700 | [diff] [blame] | 472 | next = swap_list.next; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 473 | } |
Hugh Dickins | fb4f88d | 2005-09-03 15:54:37 -0700 | [diff] [blame] | 474 | |
| 475 | nr_swap_pages++; |
| 476 | noswap: |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 477 | spin_unlock(&swap_lock); |
Hugh Dickins | fb4f88d | 2005-09-03 15:54:37 -0700 | [diff] [blame] | 478 | return (swp_entry_t) {0}; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 479 | } |
| 480 | |
Hugh Dickins | 910321e | 2010-09-09 16:38:07 -0700 | [diff] [blame] | 481 | /* The only caller of this function is now susupend routine */ |
| 482 | swp_entry_t get_swap_page_of_type(int type) |
| 483 | { |
| 484 | struct swap_info_struct *si; |
| 485 | pgoff_t offset; |
| 486 | |
| 487 | spin_lock(&swap_lock); |
| 488 | si = swap_info[type]; |
| 489 | if (si && (si->flags & SWP_WRITEOK)) { |
| 490 | nr_swap_pages--; |
| 491 | /* This is called for allocating swap entry, not cache */ |
| 492 | offset = scan_swap_map(si, 1); |
| 493 | if (offset) { |
| 494 | spin_unlock(&swap_lock); |
| 495 | return swp_entry(type, offset); |
| 496 | } |
| 497 | nr_swap_pages++; |
| 498 | } |
| 499 | spin_unlock(&swap_lock); |
| 500 | return (swp_entry_t) {0}; |
| 501 | } |
| 502 | |
Hugh Dickins | 73c34b6 | 2009-12-14 17:58:43 -0800 | [diff] [blame] | 503 | static struct swap_info_struct *swap_info_get(swp_entry_t entry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 504 | { |
Hugh Dickins | 73c34b6 | 2009-12-14 17:58:43 -0800 | [diff] [blame] | 505 | struct swap_info_struct *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 506 | unsigned long offset, type; |
| 507 | |
| 508 | if (!entry.val) |
| 509 | goto out; |
| 510 | type = swp_type(entry); |
| 511 | if (type >= nr_swapfiles) |
| 512 | goto bad_nofile; |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 513 | p = swap_info[type]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 514 | if (!(p->flags & SWP_USED)) |
| 515 | goto bad_device; |
| 516 | offset = swp_offset(entry); |
| 517 | if (offset >= p->max) |
| 518 | goto bad_offset; |
| 519 | if (!p->swap_map[offset]) |
| 520 | goto bad_free; |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 521 | spin_lock(&swap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 522 | return p; |
| 523 | |
| 524 | bad_free: |
| 525 | printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val); |
| 526 | goto out; |
| 527 | bad_offset: |
| 528 | printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val); |
| 529 | goto out; |
| 530 | bad_device: |
| 531 | printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val); |
| 532 | goto out; |
| 533 | bad_nofile: |
| 534 | printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val); |
| 535 | out: |
| 536 | return NULL; |
Hugh Dickins | 886bb7e | 2009-01-06 14:39:48 -0800 | [diff] [blame] | 537 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 538 | |
Hugh Dickins | 8d69aae | 2009-12-14 17:58:45 -0800 | [diff] [blame] | 539 | static unsigned char swap_entry_free(struct swap_info_struct *p, |
| 540 | swp_entry_t entry, unsigned char usage) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 541 | { |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 542 | unsigned long offset = swp_offset(entry); |
Hugh Dickins | 8d69aae | 2009-12-14 17:58:45 -0800 | [diff] [blame] | 543 | unsigned char count; |
| 544 | unsigned char has_cache; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 545 | |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 546 | count = p->swap_map[offset]; |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 547 | has_cache = count & SWAP_HAS_CACHE; |
| 548 | count &= ~SWAP_HAS_CACHE; |
| 549 | |
| 550 | if (usage == SWAP_HAS_CACHE) { |
| 551 | VM_BUG_ON(!has_cache); |
| 552 | has_cache = 0; |
Hugh Dickins | aaa4686 | 2009-12-14 17:58:47 -0800 | [diff] [blame] | 553 | } else if (count == SWAP_MAP_SHMEM) { |
| 554 | /* |
| 555 | * Or we could insist on shmem.c using a special |
| 556 | * swap_shmem_free() and free_shmem_swap_and_cache()... |
| 557 | */ |
| 558 | count = 0; |
Hugh Dickins | 570a335b | 2009-12-14 17:58:46 -0800 | [diff] [blame] | 559 | } else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) { |
| 560 | if (count == COUNT_CONTINUED) { |
| 561 | if (swap_count_continued(p, offset, count)) |
| 562 | count = SWAP_MAP_MAX | COUNT_CONTINUED; |
| 563 | else |
| 564 | count = SWAP_MAP_MAX; |
| 565 | } else |
| 566 | count--; |
| 567 | } |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 568 | |
| 569 | if (!count) |
| 570 | mem_cgroup_uncharge_swap(entry); |
| 571 | |
| 572 | usage = count | has_cache; |
| 573 | p->swap_map[offset] = usage; |
| 574 | |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 575 | /* free if no reference */ |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 576 | if (!usage) { |
Nitin Gupta | b3a27d0 | 2010-05-17 11:02:43 +0530 | [diff] [blame] | 577 | struct gendisk *disk = p->bdev->bd_disk; |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 578 | if (offset < p->lowest_bit) |
| 579 | p->lowest_bit = offset; |
| 580 | if (offset > p->highest_bit) |
| 581 | p->highest_bit = offset; |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 582 | if (swap_list.next >= 0 && |
| 583 | p->prio > swap_info[swap_list.next]->prio) |
| 584 | swap_list.next = p->type; |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 585 | nr_swap_pages++; |
| 586 | p->inuse_pages--; |
Nitin Gupta | b3a27d0 | 2010-05-17 11:02:43 +0530 | [diff] [blame] | 587 | if ((p->flags & SWP_BLKDEV) && |
| 588 | disk->fops->swap_slot_free_notify) |
| 589 | disk->fops->swap_slot_free_notify(p->bdev, offset); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 590 | } |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 591 | |
| 592 | return usage; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 593 | } |
| 594 | |
| 595 | /* |
| 596 | * Caller has made sure that the swapdevice corresponding to entry |
| 597 | * is still around or has not been recycled. |
| 598 | */ |
| 599 | void swap_free(swp_entry_t entry) |
| 600 | { |
Hugh Dickins | 73c34b6 | 2009-12-14 17:58:43 -0800 | [diff] [blame] | 601 | struct swap_info_struct *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 602 | |
| 603 | p = swap_info_get(entry); |
| 604 | if (p) { |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 605 | swap_entry_free(p, entry, 1); |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 606 | spin_unlock(&swap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 607 | } |
| 608 | } |
| 609 | |
| 610 | /* |
KAMEZAWA Hiroyuki | cb4b86b | 2009-06-16 15:32:52 -0700 | [diff] [blame] | 611 | * Called after dropping swapcache to decrease refcnt to swap entries. |
| 612 | */ |
| 613 | void swapcache_free(swp_entry_t entry, struct page *page) |
| 614 | { |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 615 | struct swap_info_struct *p; |
Hugh Dickins | 8d69aae | 2009-12-14 17:58:45 -0800 | [diff] [blame] | 616 | unsigned char count; |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 617 | |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 618 | p = swap_info_get(entry); |
| 619 | if (p) { |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 620 | count = swap_entry_free(p, entry, SWAP_HAS_CACHE); |
| 621 | if (page) |
| 622 | mem_cgroup_uncharge_swapcache(page, entry, count != 0); |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 623 | spin_unlock(&swap_lock); |
| 624 | } |
KAMEZAWA Hiroyuki | cb4b86b | 2009-06-16 15:32:52 -0700 | [diff] [blame] | 625 | } |
| 626 | |
| 627 | /* |
Hugh Dickins | c475a8a | 2005-06-21 17:15:12 -0700 | [diff] [blame] | 628 | * How many references to page are currently swapped out? |
Hugh Dickins | 570a335b | 2009-12-14 17:58:46 -0800 | [diff] [blame] | 629 | * This does not give an exact answer when swap count is continued, |
| 630 | * but does include the high COUNT_CONTINUED flag to allow for that. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 631 | */ |
Hugh Dickins | c475a8a | 2005-06-21 17:15:12 -0700 | [diff] [blame] | 632 | static inline int page_swapcount(struct page *page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 633 | { |
Hugh Dickins | c475a8a | 2005-06-21 17:15:12 -0700 | [diff] [blame] | 634 | int count = 0; |
| 635 | struct swap_info_struct *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 636 | swp_entry_t entry; |
| 637 | |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 638 | entry.val = page_private(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 639 | p = swap_info_get(entry); |
| 640 | if (p) { |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 641 | count = swap_count(p->swap_map[swp_offset(entry)]); |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 642 | spin_unlock(&swap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 643 | } |
Hugh Dickins | c475a8a | 2005-06-21 17:15:12 -0700 | [diff] [blame] | 644 | return count; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 645 | } |
| 646 | |
| 647 | /* |
Hugh Dickins | 7b1fe59 | 2009-01-06 14:39:34 -0800 | [diff] [blame] | 648 | * We can write to an anon page without COW if there are no other references |
| 649 | * to it. And as a side-effect, free up its swap: because the old content |
| 650 | * on disk will never be read, and seeking back there to write new content |
| 651 | * later would only waste time away from clustering. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 652 | */ |
Hugh Dickins | 7b1fe59 | 2009-01-06 14:39:34 -0800 | [diff] [blame] | 653 | int reuse_swap_page(struct page *page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 654 | { |
Hugh Dickins | c475a8a | 2005-06-21 17:15:12 -0700 | [diff] [blame] | 655 | int count; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 656 | |
Hugh Dickins | 51726b1 | 2009-01-06 14:39:25 -0800 | [diff] [blame] | 657 | VM_BUG_ON(!PageLocked(page)); |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 658 | if (unlikely(PageKsm(page))) |
| 659 | return 0; |
Hugh Dickins | c475a8a | 2005-06-21 17:15:12 -0700 | [diff] [blame] | 660 | count = page_mapcount(page); |
Hugh Dickins | 7b1fe59 | 2009-01-06 14:39:34 -0800 | [diff] [blame] | 661 | if (count <= 1 && PageSwapCache(page)) { |
Hugh Dickins | c475a8a | 2005-06-21 17:15:12 -0700 | [diff] [blame] | 662 | count += page_swapcount(page); |
Hugh Dickins | 7b1fe59 | 2009-01-06 14:39:34 -0800 | [diff] [blame] | 663 | if (count == 1 && !PageWriteback(page)) { |
| 664 | delete_from_swap_cache(page); |
| 665 | SetPageDirty(page); |
| 666 | } |
| 667 | } |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 668 | return count <= 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 669 | } |
| 670 | |
| 671 | /* |
Hugh Dickins | a2c43ee | 2009-01-06 14:39:36 -0800 | [diff] [blame] | 672 | * If swap is getting full, or if there are no more mappings of this page, |
| 673 | * then try_to_free_swap is called to free its swap space. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 674 | */ |
Hugh Dickins | a2c43ee | 2009-01-06 14:39:36 -0800 | [diff] [blame] | 675 | int try_to_free_swap(struct page *page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 676 | { |
Hugh Dickins | 51726b1 | 2009-01-06 14:39:25 -0800 | [diff] [blame] | 677 | VM_BUG_ON(!PageLocked(page)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 678 | |
| 679 | if (!PageSwapCache(page)) |
| 680 | return 0; |
| 681 | if (PageWriteback(page)) |
| 682 | return 0; |
Hugh Dickins | a2c43ee | 2009-01-06 14:39:36 -0800 | [diff] [blame] | 683 | if (page_swapcount(page)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 684 | return 0; |
| 685 | |
Hugh Dickins | b73d7fc | 2010-09-09 16:38:09 -0700 | [diff] [blame] | 686 | /* |
| 687 | * Once hibernation has begun to create its image of memory, |
| 688 | * there's a danger that one of the calls to try_to_free_swap() |
| 689 | * - most probably a call from __try_to_reclaim_swap() while |
| 690 | * hibernation is allocating its own swap pages for the image, |
| 691 | * but conceivably even a call from memory reclaim - will free |
| 692 | * the swap from a page which has already been recorded in the |
| 693 | * image as a clean swapcache page, and then reuse its swap for |
| 694 | * another page of the image. On waking from hibernation, the |
| 695 | * original page might be freed under memory pressure, then |
| 696 | * later read back in from swap, now with the wrong data. |
| 697 | * |
| 698 | * Hibernation clears bits from gfp_allowed_mask to prevent |
| 699 | * memory reclaim from writing to disk, so check that here. |
| 700 | */ |
| 701 | if (!(gfp_allowed_mask & __GFP_IO)) |
| 702 | return 0; |
| 703 | |
Hugh Dickins | a2c43ee | 2009-01-06 14:39:36 -0800 | [diff] [blame] | 704 | delete_from_swap_cache(page); |
| 705 | SetPageDirty(page); |
| 706 | return 1; |
Rik van Riel | 68a22394 | 2008-10-18 20:26:23 -0700 | [diff] [blame] | 707 | } |
| 708 | |
| 709 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 710 | * Free the swap entry like above, but also try to |
| 711 | * free the page cache entry if it is the last user. |
| 712 | */ |
Hugh Dickins | 2509ef2 | 2009-01-06 14:40:10 -0800 | [diff] [blame] | 713 | int free_swap_and_cache(swp_entry_t entry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 714 | { |
Hugh Dickins | 2509ef2 | 2009-01-06 14:40:10 -0800 | [diff] [blame] | 715 | struct swap_info_struct *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 716 | struct page *page = NULL; |
| 717 | |
Andi Kleen | a7420aa | 2009-09-16 11:50:05 +0200 | [diff] [blame] | 718 | if (non_swap_entry(entry)) |
Hugh Dickins | 2509ef2 | 2009-01-06 14:40:10 -0800 | [diff] [blame] | 719 | return 1; |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 720 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 721 | p = swap_info_get(entry); |
| 722 | if (p) { |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 723 | if (swap_entry_free(p, entry, 1) == SWAP_HAS_CACHE) { |
Nick Piggin | 93fac70 | 2006-03-31 02:29:56 -0800 | [diff] [blame] | 724 | page = find_get_page(&swapper_space, entry.val); |
Nick Piggin | 8413ac9 | 2008-10-18 20:26:59 -0700 | [diff] [blame] | 725 | if (page && !trylock_page(page)) { |
Nick Piggin | 93fac70 | 2006-03-31 02:29:56 -0800 | [diff] [blame] | 726 | page_cache_release(page); |
| 727 | page = NULL; |
| 728 | } |
| 729 | } |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 730 | spin_unlock(&swap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 731 | } |
| 732 | if (page) { |
Hugh Dickins | a2c43ee | 2009-01-06 14:39:36 -0800 | [diff] [blame] | 733 | /* |
| 734 | * Not mapped elsewhere, or swap space full? Free it! |
| 735 | * Also recheck PageSwapCache now page is locked (above). |
| 736 | */ |
Nick Piggin | 93fac70 | 2006-03-31 02:29:56 -0800 | [diff] [blame] | 737 | if (PageSwapCache(page) && !PageWriteback(page) && |
Hugh Dickins | a2c43ee | 2009-01-06 14:39:36 -0800 | [diff] [blame] | 738 | (!page_mapped(page) || vm_swap_full())) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 739 | delete_from_swap_cache(page); |
| 740 | SetPageDirty(page); |
| 741 | } |
| 742 | unlock_page(page); |
| 743 | page_cache_release(page); |
| 744 | } |
Hugh Dickins | 2509ef2 | 2009-01-06 14:40:10 -0800 | [diff] [blame] | 745 | return p != NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 746 | } |
| 747 | |
Daisuke Nishimura | 0249144 | 2010-03-10 15:22:17 -0800 | [diff] [blame] | 748 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
| 749 | /** |
| 750 | * mem_cgroup_count_swap_user - count the user of a swap entry |
| 751 | * @ent: the swap entry to be checked |
| 752 | * @pagep: the pointer for the swap cache page of the entry to be stored |
| 753 | * |
| 754 | * Returns the number of the user of the swap entry. The number is valid only |
| 755 | * for swaps of anonymous pages. |
| 756 | * If the entry is found on swap cache, the page is stored to pagep with |
| 757 | * refcount of it being incremented. |
| 758 | */ |
| 759 | int mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep) |
| 760 | { |
| 761 | struct page *page; |
| 762 | struct swap_info_struct *p; |
| 763 | int count = 0; |
| 764 | |
| 765 | page = find_get_page(&swapper_space, ent.val); |
| 766 | if (page) |
| 767 | count += page_mapcount(page); |
| 768 | p = swap_info_get(ent); |
| 769 | if (p) { |
| 770 | count += swap_count(p->swap_map[swp_offset(ent)]); |
| 771 | spin_unlock(&swap_lock); |
| 772 | } |
| 773 | |
| 774 | *pagep = page; |
| 775 | return count; |
| 776 | } |
| 777 | #endif |
| 778 | |
Rafael J. Wysocki | b0cb1a1 | 2007-07-29 23:24:36 +0200 | [diff] [blame] | 779 | #ifdef CONFIG_HIBERNATION |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 780 | /* |
Rafael J. Wysocki | 915bae9 | 2006-12-06 20:34:07 -0800 | [diff] [blame] | 781 | * Find the swap type that corresponds to given device (if any). |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 782 | * |
Rafael J. Wysocki | 915bae9 | 2006-12-06 20:34:07 -0800 | [diff] [blame] | 783 | * @offset - number of the PAGE_SIZE-sized block of the device, starting |
| 784 | * from 0, in which the swap header is expected to be located. |
| 785 | * |
| 786 | * This is needed for the suspend to disk (aka swsusp). |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 787 | */ |
Rafael J. Wysocki | 7bf2368 | 2007-01-05 16:36:28 -0800 | [diff] [blame] | 788 | int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 789 | { |
Rafael J. Wysocki | 915bae9 | 2006-12-06 20:34:07 -0800 | [diff] [blame] | 790 | struct block_device *bdev = NULL; |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 791 | int type; |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 792 | |
Rafael J. Wysocki | 915bae9 | 2006-12-06 20:34:07 -0800 | [diff] [blame] | 793 | if (device) |
| 794 | bdev = bdget(device); |
| 795 | |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 796 | spin_lock(&swap_lock); |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 797 | for (type = 0; type < nr_swapfiles; type++) { |
| 798 | struct swap_info_struct *sis = swap_info[type]; |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 799 | |
Rafael J. Wysocki | 915bae9 | 2006-12-06 20:34:07 -0800 | [diff] [blame] | 800 | if (!(sis->flags & SWP_WRITEOK)) |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 801 | continue; |
Rafael J. Wysocki | b6b5bce | 2006-08-27 01:23:25 -0700 | [diff] [blame] | 802 | |
Rafael J. Wysocki | 915bae9 | 2006-12-06 20:34:07 -0800 | [diff] [blame] | 803 | if (!bdev) { |
Rafael J. Wysocki | 7bf2368 | 2007-01-05 16:36:28 -0800 | [diff] [blame] | 804 | if (bdev_p) |
Alan Jenkins | dddac6a | 2009-07-29 21:07:55 +0200 | [diff] [blame] | 805 | *bdev_p = bdgrab(sis->bdev); |
Rafael J. Wysocki | 7bf2368 | 2007-01-05 16:36:28 -0800 | [diff] [blame] | 806 | |
Rafael J. Wysocki | 6e1819d | 2006-03-23 03:00:03 -0800 | [diff] [blame] | 807 | spin_unlock(&swap_lock); |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 808 | return type; |
Rafael J. Wysocki | 6e1819d | 2006-03-23 03:00:03 -0800 | [diff] [blame] | 809 | } |
Rafael J. Wysocki | 915bae9 | 2006-12-06 20:34:07 -0800 | [diff] [blame] | 810 | if (bdev == sis->bdev) { |
Hugh Dickins | 9625a5f | 2009-12-14 17:58:42 -0800 | [diff] [blame] | 811 | struct swap_extent *se = &sis->first_swap_extent; |
Rafael J. Wysocki | 915bae9 | 2006-12-06 20:34:07 -0800 | [diff] [blame] | 812 | |
Rafael J. Wysocki | 915bae9 | 2006-12-06 20:34:07 -0800 | [diff] [blame] | 813 | if (se->start_block == offset) { |
Rafael J. Wysocki | 7bf2368 | 2007-01-05 16:36:28 -0800 | [diff] [blame] | 814 | if (bdev_p) |
Alan Jenkins | dddac6a | 2009-07-29 21:07:55 +0200 | [diff] [blame] | 815 | *bdev_p = bdgrab(sis->bdev); |
Rafael J. Wysocki | 7bf2368 | 2007-01-05 16:36:28 -0800 | [diff] [blame] | 816 | |
Rafael J. Wysocki | 915bae9 | 2006-12-06 20:34:07 -0800 | [diff] [blame] | 817 | spin_unlock(&swap_lock); |
| 818 | bdput(bdev); |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 819 | return type; |
Rafael J. Wysocki | 915bae9 | 2006-12-06 20:34:07 -0800 | [diff] [blame] | 820 | } |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 821 | } |
| 822 | } |
| 823 | spin_unlock(&swap_lock); |
Rafael J. Wysocki | 915bae9 | 2006-12-06 20:34:07 -0800 | [diff] [blame] | 824 | if (bdev) |
| 825 | bdput(bdev); |
| 826 | |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 827 | return -ENODEV; |
| 828 | } |
| 829 | |
| 830 | /* |
Hugh Dickins | 73c34b6 | 2009-12-14 17:58:43 -0800 | [diff] [blame] | 831 | * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev |
| 832 | * corresponding to given index in swap_info (swap type). |
| 833 | */ |
| 834 | sector_t swapdev_block(int type, pgoff_t offset) |
| 835 | { |
| 836 | struct block_device *bdev; |
| 837 | |
| 838 | if ((unsigned int)type >= nr_swapfiles) |
| 839 | return 0; |
| 840 | if (!(swap_info[type]->flags & SWP_WRITEOK)) |
| 841 | return 0; |
Lee Schermerhorn | d4906e1 | 2009-12-14 17:58:49 -0800 | [diff] [blame] | 842 | return map_swap_entry(swp_entry(type, offset), &bdev); |
Hugh Dickins | 73c34b6 | 2009-12-14 17:58:43 -0800 | [diff] [blame] | 843 | } |
| 844 | |
| 845 | /* |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 846 | * Return either the total number of swap pages of given type, or the number |
| 847 | * of free pages of that type (depending on @free) |
| 848 | * |
| 849 | * This is needed for software suspend |
| 850 | */ |
| 851 | unsigned int count_swap_pages(int type, int free) |
| 852 | { |
| 853 | unsigned int n = 0; |
| 854 | |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 855 | spin_lock(&swap_lock); |
| 856 | if ((unsigned int)type < nr_swapfiles) { |
| 857 | struct swap_info_struct *sis = swap_info[type]; |
| 858 | |
| 859 | if (sis->flags & SWP_WRITEOK) { |
| 860 | n = sis->pages; |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 861 | if (free) |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 862 | n -= sis->inuse_pages; |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 863 | } |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 864 | } |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 865 | spin_unlock(&swap_lock); |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 866 | return n; |
| 867 | } |
Hugh Dickins | 73c34b6 | 2009-12-14 17:58:43 -0800 | [diff] [blame] | 868 | #endif /* CONFIG_HIBERNATION */ |
Rafael J. Wysocki | f577eb3 | 2006-03-23 02:59:59 -0800 | [diff] [blame] | 869 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 870 | /* |
Hugh Dickins | 72866f6 | 2005-10-29 18:15:55 -0700 | [diff] [blame] | 871 | * No need to decide whether this PTE shares the swap entry with others, |
| 872 | * just let do_wp_page work it out if a write is requested later - to |
| 873 | * force COW, vm_page_prot omits write permission from any private vma. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 874 | */ |
Hugh Dickins | 044d66c | 2008-02-07 00:14:04 -0800 | [diff] [blame] | 875 | static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 876 | unsigned long addr, swp_entry_t entry, struct page *page) |
| 877 | { |
KAMEZAWA Hiroyuki | 7a81b88 | 2009-01-07 18:07:48 -0800 | [diff] [blame] | 878 | struct mem_cgroup *ptr = NULL; |
Hugh Dickins | 044d66c | 2008-02-07 00:14:04 -0800 | [diff] [blame] | 879 | spinlock_t *ptl; |
| 880 | pte_t *pte; |
| 881 | int ret = 1; |
| 882 | |
KAMEZAWA Hiroyuki | 85d9fc8 | 2009-01-29 14:25:13 -0800 | [diff] [blame] | 883 | if (mem_cgroup_try_charge_swapin(vma->vm_mm, page, GFP_KERNEL, &ptr)) { |
Hugh Dickins | 044d66c | 2008-02-07 00:14:04 -0800 | [diff] [blame] | 884 | ret = -ENOMEM; |
KAMEZAWA Hiroyuki | 85d9fc8 | 2009-01-29 14:25:13 -0800 | [diff] [blame] | 885 | goto out_nolock; |
| 886 | } |
Hugh Dickins | 044d66c | 2008-02-07 00:14:04 -0800 | [diff] [blame] | 887 | |
| 888 | pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); |
| 889 | if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) { |
| 890 | if (ret > 0) |
KAMEZAWA Hiroyuki | 7a81b88 | 2009-01-07 18:07:48 -0800 | [diff] [blame] | 891 | mem_cgroup_cancel_charge_swapin(ptr); |
Hugh Dickins | 044d66c | 2008-02-07 00:14:04 -0800 | [diff] [blame] | 892 | ret = 0; |
| 893 | goto out; |
| 894 | } |
Balbir Singh | 8a9f3cc | 2008-02-07 00:13:53 -0800 | [diff] [blame] | 895 | |
KAMEZAWA Hiroyuki | b084d43 | 2010-03-05 13:41:42 -0800 | [diff] [blame] | 896 | dec_mm_counter(vma->vm_mm, MM_SWAPENTS); |
KAMEZAWA Hiroyuki | d559db0 | 2010-03-05 13:41:39 -0800 | [diff] [blame] | 897 | inc_mm_counter(vma->vm_mm, MM_ANONPAGES); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 898 | get_page(page); |
| 899 | set_pte_at(vma->vm_mm, addr, pte, |
| 900 | pte_mkold(mk_pte(page, vma->vm_page_prot))); |
| 901 | page_add_anon_rmap(page, vma, addr); |
KAMEZAWA Hiroyuki | 7a81b88 | 2009-01-07 18:07:48 -0800 | [diff] [blame] | 902 | mem_cgroup_commit_charge_swapin(page, ptr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 903 | swap_free(entry); |
| 904 | /* |
| 905 | * Move the page to the active list so it is not |
| 906 | * immediately swapped out again after swapon. |
| 907 | */ |
| 908 | activate_page(page); |
Hugh Dickins | 044d66c | 2008-02-07 00:14:04 -0800 | [diff] [blame] | 909 | out: |
| 910 | pte_unmap_unlock(pte, ptl); |
KAMEZAWA Hiroyuki | 85d9fc8 | 2009-01-29 14:25:13 -0800 | [diff] [blame] | 911 | out_nolock: |
Hugh Dickins | 044d66c | 2008-02-07 00:14:04 -0800 | [diff] [blame] | 912 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 913 | } |
| 914 | |
| 915 | static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, |
| 916 | unsigned long addr, unsigned long end, |
| 917 | swp_entry_t entry, struct page *page) |
| 918 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 919 | pte_t swp_pte = swp_entry_to_pte(entry); |
Hugh Dickins | 705e87c | 2005-10-29 18:16:27 -0700 | [diff] [blame] | 920 | pte_t *pte; |
Balbir Singh | 8a9f3cc | 2008-02-07 00:13:53 -0800 | [diff] [blame] | 921 | int ret = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 922 | |
Hugh Dickins | 044d66c | 2008-02-07 00:14:04 -0800 | [diff] [blame] | 923 | /* |
| 924 | * We don't actually need pte lock while scanning for swp_pte: since |
| 925 | * we hold page lock and mmap_sem, swp_pte cannot be inserted into the |
| 926 | * page table while we're scanning; though it could get zapped, and on |
| 927 | * some architectures (e.g. x86_32 with PAE) we might catch a glimpse |
| 928 | * of unmatched parts which look like swp_pte, so unuse_pte must |
| 929 | * recheck under pte lock. Scanning without pte lock lets it be |
| 930 | * preemptible whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE. |
| 931 | */ |
| 932 | pte = pte_offset_map(pmd, addr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 933 | do { |
| 934 | /* |
| 935 | * swapoff spends a _lot_ of time in this loop! |
| 936 | * Test inline before going to call unuse_pte. |
| 937 | */ |
| 938 | if (unlikely(pte_same(*pte, swp_pte))) { |
Hugh Dickins | 044d66c | 2008-02-07 00:14:04 -0800 | [diff] [blame] | 939 | pte_unmap(pte); |
| 940 | ret = unuse_pte(vma, pmd, addr, entry, page); |
| 941 | if (ret) |
| 942 | goto out; |
| 943 | pte = pte_offset_map(pmd, addr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 944 | } |
| 945 | } while (pte++, addr += PAGE_SIZE, addr != end); |
Hugh Dickins | 044d66c | 2008-02-07 00:14:04 -0800 | [diff] [blame] | 946 | pte_unmap(pte - 1); |
| 947 | out: |
Balbir Singh | 8a9f3cc | 2008-02-07 00:13:53 -0800 | [diff] [blame] | 948 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 949 | } |
| 950 | |
| 951 | static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, |
| 952 | unsigned long addr, unsigned long end, |
| 953 | swp_entry_t entry, struct page *page) |
| 954 | { |
| 955 | pmd_t *pmd; |
| 956 | unsigned long next; |
Balbir Singh | 8a9f3cc | 2008-02-07 00:13:53 -0800 | [diff] [blame] | 957 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 958 | |
| 959 | pmd = pmd_offset(pud, addr); |
| 960 | do { |
| 961 | next = pmd_addr_end(addr, end); |
| 962 | if (pmd_none_or_clear_bad(pmd)) |
| 963 | continue; |
Balbir Singh | 8a9f3cc | 2008-02-07 00:13:53 -0800 | [diff] [blame] | 964 | ret = unuse_pte_range(vma, pmd, addr, next, entry, page); |
| 965 | if (ret) |
| 966 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 967 | } while (pmd++, addr = next, addr != end); |
| 968 | return 0; |
| 969 | } |
| 970 | |
| 971 | static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd, |
| 972 | unsigned long addr, unsigned long end, |
| 973 | swp_entry_t entry, struct page *page) |
| 974 | { |
| 975 | pud_t *pud; |
| 976 | unsigned long next; |
Balbir Singh | 8a9f3cc | 2008-02-07 00:13:53 -0800 | [diff] [blame] | 977 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 978 | |
| 979 | pud = pud_offset(pgd, addr); |
| 980 | do { |
| 981 | next = pud_addr_end(addr, end); |
| 982 | if (pud_none_or_clear_bad(pud)) |
| 983 | continue; |
Balbir Singh | 8a9f3cc | 2008-02-07 00:13:53 -0800 | [diff] [blame] | 984 | ret = unuse_pmd_range(vma, pud, addr, next, entry, page); |
| 985 | if (ret) |
| 986 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 987 | } while (pud++, addr = next, addr != end); |
| 988 | return 0; |
| 989 | } |
| 990 | |
| 991 | static int unuse_vma(struct vm_area_struct *vma, |
| 992 | swp_entry_t entry, struct page *page) |
| 993 | { |
| 994 | pgd_t *pgd; |
| 995 | unsigned long addr, end, next; |
Balbir Singh | 8a9f3cc | 2008-02-07 00:13:53 -0800 | [diff] [blame] | 996 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 997 | |
Hugh Dickins | 3ca7b3c | 2009-12-14 17:58:57 -0800 | [diff] [blame] | 998 | if (page_anon_vma(page)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 999 | addr = page_address_in_vma(page, vma); |
| 1000 | if (addr == -EFAULT) |
| 1001 | return 0; |
| 1002 | else |
| 1003 | end = addr + PAGE_SIZE; |
| 1004 | } else { |
| 1005 | addr = vma->vm_start; |
| 1006 | end = vma->vm_end; |
| 1007 | } |
| 1008 | |
| 1009 | pgd = pgd_offset(vma->vm_mm, addr); |
| 1010 | do { |
| 1011 | next = pgd_addr_end(addr, end); |
| 1012 | if (pgd_none_or_clear_bad(pgd)) |
| 1013 | continue; |
Balbir Singh | 8a9f3cc | 2008-02-07 00:13:53 -0800 | [diff] [blame] | 1014 | ret = unuse_pud_range(vma, pgd, addr, next, entry, page); |
| 1015 | if (ret) |
| 1016 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1017 | } while (pgd++, addr = next, addr != end); |
| 1018 | return 0; |
| 1019 | } |
| 1020 | |
| 1021 | static int unuse_mm(struct mm_struct *mm, |
| 1022 | swp_entry_t entry, struct page *page) |
| 1023 | { |
| 1024 | struct vm_area_struct *vma; |
Balbir Singh | 8a9f3cc | 2008-02-07 00:13:53 -0800 | [diff] [blame] | 1025 | int ret = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1026 | |
| 1027 | if (!down_read_trylock(&mm->mmap_sem)) { |
| 1028 | /* |
Fernando Luis Vazquez Cao | 7d03431 | 2008-07-29 22:33:41 -0700 | [diff] [blame] | 1029 | * Activate page so shrink_inactive_list is unlikely to unmap |
| 1030 | * its ptes while lock is dropped, so swapoff can make progress. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1031 | */ |
Hugh Dickins | c475a8a | 2005-06-21 17:15:12 -0700 | [diff] [blame] | 1032 | activate_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1033 | unlock_page(page); |
| 1034 | down_read(&mm->mmap_sem); |
| 1035 | lock_page(page); |
| 1036 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1037 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
Balbir Singh | 8a9f3cc | 2008-02-07 00:13:53 -0800 | [diff] [blame] | 1038 | if (vma->anon_vma && (ret = unuse_vma(vma, entry, page))) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1039 | break; |
| 1040 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1041 | up_read(&mm->mmap_sem); |
Balbir Singh | 8a9f3cc | 2008-02-07 00:13:53 -0800 | [diff] [blame] | 1042 | return (ret < 0)? ret: 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1043 | } |
| 1044 | |
| 1045 | /* |
| 1046 | * Scan swap_map from current position to next entry still in use. |
| 1047 | * Recycle to start on reaching the end, returning 0 when empty. |
| 1048 | */ |
Hugh Dickins | 6eb396d | 2005-09-03 15:54:35 -0700 | [diff] [blame] | 1049 | static unsigned int find_next_to_unuse(struct swap_info_struct *si, |
| 1050 | unsigned int prev) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1051 | { |
Hugh Dickins | 6eb396d | 2005-09-03 15:54:35 -0700 | [diff] [blame] | 1052 | unsigned int max = si->max; |
| 1053 | unsigned int i = prev; |
Hugh Dickins | 8d69aae | 2009-12-14 17:58:45 -0800 | [diff] [blame] | 1054 | unsigned char count; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1055 | |
| 1056 | /* |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1057 | * No need for swap_lock here: we're just looking |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1058 | * for whether an entry is in use, not modifying it; false |
| 1059 | * hits are okay, and sys_swapoff() has already prevented new |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1060 | * allocations from this area (while holding swap_lock). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1061 | */ |
| 1062 | for (;;) { |
| 1063 | if (++i >= max) { |
| 1064 | if (!prev) { |
| 1065 | i = 0; |
| 1066 | break; |
| 1067 | } |
| 1068 | /* |
| 1069 | * No entries in use at top of swap_map, |
| 1070 | * loop back to start and recheck there. |
| 1071 | */ |
| 1072 | max = prev + 1; |
| 1073 | prev = 0; |
| 1074 | i = 1; |
| 1075 | } |
| 1076 | count = si->swap_map[i]; |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 1077 | if (count && swap_count(count) != SWAP_MAP_BAD) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1078 | break; |
| 1079 | } |
| 1080 | return i; |
| 1081 | } |
| 1082 | |
| 1083 | /* |
| 1084 | * We completely avoid races by reading each swap page in advance, |
| 1085 | * and then search for the process using it. All the necessary |
| 1086 | * page table adjustments can then be made atomically. |
| 1087 | */ |
| 1088 | static int try_to_unuse(unsigned int type) |
| 1089 | { |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1090 | struct swap_info_struct *si = swap_info[type]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1091 | struct mm_struct *start_mm; |
Hugh Dickins | 8d69aae | 2009-12-14 17:58:45 -0800 | [diff] [blame] | 1092 | unsigned char *swap_map; |
| 1093 | unsigned char swcount; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1094 | struct page *page; |
| 1095 | swp_entry_t entry; |
Hugh Dickins | 6eb396d | 2005-09-03 15:54:35 -0700 | [diff] [blame] | 1096 | unsigned int i = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1097 | int retval = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1098 | |
| 1099 | /* |
| 1100 | * When searching mms for an entry, a good strategy is to |
| 1101 | * start at the first mm we freed the previous entry from |
| 1102 | * (though actually we don't notice whether we or coincidence |
| 1103 | * freed the entry). Initialize this start_mm with a hold. |
| 1104 | * |
| 1105 | * A simpler strategy would be to start at the last mm we |
| 1106 | * freed the previous entry from; but that would take less |
| 1107 | * advantage of mmlist ordering, which clusters forked mms |
| 1108 | * together, child after parent. If we race with dup_mmap(), we |
| 1109 | * prefer to resolve parent before child, lest we miss entries |
| 1110 | * duplicated after we scanned child: using last mm would invert |
Hugh Dickins | 570a335b | 2009-12-14 17:58:46 -0800 | [diff] [blame] | 1111 | * that. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1112 | */ |
| 1113 | start_mm = &init_mm; |
| 1114 | atomic_inc(&init_mm.mm_users); |
| 1115 | |
| 1116 | /* |
| 1117 | * Keep on scanning until all entries have gone. Usually, |
| 1118 | * one pass through swap_map is enough, but not necessarily: |
| 1119 | * there are races when an instance of an entry might be missed. |
| 1120 | */ |
| 1121 | while ((i = find_next_to_unuse(si, i)) != 0) { |
| 1122 | if (signal_pending(current)) { |
| 1123 | retval = -EINTR; |
| 1124 | break; |
| 1125 | } |
| 1126 | |
Hugh Dickins | 886bb7e | 2009-01-06 14:39:48 -0800 | [diff] [blame] | 1127 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1128 | * Get a page for the entry, using the existing swap |
| 1129 | * cache page if there is one. Otherwise, get a clean |
Hugh Dickins | 886bb7e | 2009-01-06 14:39:48 -0800 | [diff] [blame] | 1130 | * page and read the swap into it. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1131 | */ |
| 1132 | swap_map = &si->swap_map[i]; |
| 1133 | entry = swp_entry(type, i); |
Hugh Dickins | 02098fe | 2008-02-04 22:28:42 -0800 | [diff] [blame] | 1134 | page = read_swap_cache_async(entry, |
| 1135 | GFP_HIGHUSER_MOVABLE, NULL, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1136 | if (!page) { |
| 1137 | /* |
| 1138 | * Either swap_duplicate() failed because entry |
| 1139 | * has been freed independently, and will not be |
| 1140 | * reused since sys_swapoff() already disabled |
| 1141 | * allocation from here, or alloc_page() failed. |
| 1142 | */ |
| 1143 | if (!*swap_map) |
| 1144 | continue; |
| 1145 | retval = -ENOMEM; |
| 1146 | break; |
| 1147 | } |
| 1148 | |
| 1149 | /* |
| 1150 | * Don't hold on to start_mm if it looks like exiting. |
| 1151 | */ |
| 1152 | if (atomic_read(&start_mm->mm_users) == 1) { |
| 1153 | mmput(start_mm); |
| 1154 | start_mm = &init_mm; |
| 1155 | atomic_inc(&init_mm.mm_users); |
| 1156 | } |
| 1157 | |
| 1158 | /* |
| 1159 | * Wait for and lock page. When do_swap_page races with |
| 1160 | * try_to_unuse, do_swap_page can handle the fault much |
| 1161 | * faster than try_to_unuse can locate the entry. This |
| 1162 | * apparently redundant "wait_on_page_locked" lets try_to_unuse |
| 1163 | * defer to do_swap_page in such a case - in some tests, |
| 1164 | * do_swap_page and try_to_unuse repeatedly compete. |
| 1165 | */ |
| 1166 | wait_on_page_locked(page); |
| 1167 | wait_on_page_writeback(page); |
| 1168 | lock_page(page); |
| 1169 | wait_on_page_writeback(page); |
| 1170 | |
| 1171 | /* |
| 1172 | * Remove all references to entry. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1173 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1174 | swcount = *swap_map; |
Hugh Dickins | aaa4686 | 2009-12-14 17:58:47 -0800 | [diff] [blame] | 1175 | if (swap_count(swcount) == SWAP_MAP_SHMEM) { |
| 1176 | retval = shmem_unuse(entry, page); |
| 1177 | /* page has already been unlocked and released */ |
| 1178 | if (retval < 0) |
| 1179 | break; |
| 1180 | continue; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1181 | } |
Hugh Dickins | aaa4686 | 2009-12-14 17:58:47 -0800 | [diff] [blame] | 1182 | if (swap_count(swcount) && start_mm != &init_mm) |
| 1183 | retval = unuse_mm(start_mm, entry, page); |
| 1184 | |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 1185 | if (swap_count(*swap_map)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1186 | int set_start_mm = (*swap_map >= swcount); |
| 1187 | struct list_head *p = &start_mm->mmlist; |
| 1188 | struct mm_struct *new_start_mm = start_mm; |
| 1189 | struct mm_struct *prev_mm = start_mm; |
| 1190 | struct mm_struct *mm; |
| 1191 | |
| 1192 | atomic_inc(&new_start_mm->mm_users); |
| 1193 | atomic_inc(&prev_mm->mm_users); |
| 1194 | spin_lock(&mmlist_lock); |
Hugh Dickins | aaa4686 | 2009-12-14 17:58:47 -0800 | [diff] [blame] | 1195 | while (swap_count(*swap_map) && !retval && |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1196 | (p = p->next) != &start_mm->mmlist) { |
| 1197 | mm = list_entry(p, struct mm_struct, mmlist); |
Hugh Dickins | 70af7c5 | 2006-06-23 02:03:44 -0700 | [diff] [blame] | 1198 | if (!atomic_inc_not_zero(&mm->mm_users)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1199 | continue; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1200 | spin_unlock(&mmlist_lock); |
| 1201 | mmput(prev_mm); |
| 1202 | prev_mm = mm; |
| 1203 | |
| 1204 | cond_resched(); |
| 1205 | |
| 1206 | swcount = *swap_map; |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 1207 | if (!swap_count(swcount)) /* any usage ? */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1208 | ; |
Hugh Dickins | aaa4686 | 2009-12-14 17:58:47 -0800 | [diff] [blame] | 1209 | else if (mm == &init_mm) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1210 | set_start_mm = 1; |
Hugh Dickins | aaa4686 | 2009-12-14 17:58:47 -0800 | [diff] [blame] | 1211 | else |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1212 | retval = unuse_mm(mm, entry, page); |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 1213 | |
Bo Liu | 32c5fc1 | 2009-11-02 16:50:33 +0000 | [diff] [blame] | 1214 | if (set_start_mm && *swap_map < swcount) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1215 | mmput(new_start_mm); |
| 1216 | atomic_inc(&mm->mm_users); |
| 1217 | new_start_mm = mm; |
| 1218 | set_start_mm = 0; |
| 1219 | } |
| 1220 | spin_lock(&mmlist_lock); |
| 1221 | } |
| 1222 | spin_unlock(&mmlist_lock); |
| 1223 | mmput(prev_mm); |
| 1224 | mmput(start_mm); |
| 1225 | start_mm = new_start_mm; |
| 1226 | } |
| 1227 | if (retval) { |
| 1228 | unlock_page(page); |
| 1229 | page_cache_release(page); |
| 1230 | break; |
| 1231 | } |
| 1232 | |
| 1233 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1234 | * If a reference remains (rare), we would like to leave |
| 1235 | * the page in the swap cache; but try_to_unmap could |
| 1236 | * then re-duplicate the entry once we drop page lock, |
| 1237 | * so we might loop indefinitely; also, that page could |
| 1238 | * not be swapped out to other storage meanwhile. So: |
| 1239 | * delete from cache even if there's another reference, |
| 1240 | * after ensuring that the data has been saved to disk - |
| 1241 | * since if the reference remains (rarer), it will be |
| 1242 | * read from disk into another page. Splitting into two |
| 1243 | * pages would be incorrect if swap supported "shared |
| 1244 | * private" pages, but they are handled by tmpfs files. |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 1245 | * |
| 1246 | * Given how unuse_vma() targets one particular offset |
| 1247 | * in an anon_vma, once the anon_vma has been determined, |
| 1248 | * this splitting happens to be just what is needed to |
| 1249 | * handle where KSM pages have been swapped out: re-reading |
| 1250 | * is unnecessarily slow, but we can fix that later on. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1251 | */ |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 1252 | if (swap_count(*swap_map) && |
| 1253 | PageDirty(page) && PageSwapCache(page)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1254 | struct writeback_control wbc = { |
| 1255 | .sync_mode = WB_SYNC_NONE, |
| 1256 | }; |
| 1257 | |
| 1258 | swap_writepage(page, &wbc); |
| 1259 | lock_page(page); |
| 1260 | wait_on_page_writeback(page); |
| 1261 | } |
Hugh Dickins | 68bdc8d | 2009-01-06 14:39:37 -0800 | [diff] [blame] | 1262 | |
| 1263 | /* |
| 1264 | * It is conceivable that a racing task removed this page from |
| 1265 | * swap cache just before we acquired the page lock at the top, |
| 1266 | * or while we dropped it in unuse_mm(). The page might even |
| 1267 | * be back in swap cache on another swap area: that we must not |
| 1268 | * delete, since it may not have been written out to swap yet. |
| 1269 | */ |
| 1270 | if (PageSwapCache(page) && |
| 1271 | likely(page_private(page) == entry.val)) |
Hugh Dickins | 2e0e26c | 2008-02-04 22:28:53 -0800 | [diff] [blame] | 1272 | delete_from_swap_cache(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1273 | |
| 1274 | /* |
| 1275 | * So we could skip searching mms once swap count went |
| 1276 | * to 1, we did not mark any present ptes as dirty: must |
Anderson Briglia | 2706a1b | 2007-07-15 23:38:09 -0700 | [diff] [blame] | 1277 | * mark page dirty so shrink_page_list will preserve it. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1278 | */ |
| 1279 | SetPageDirty(page); |
| 1280 | unlock_page(page); |
| 1281 | page_cache_release(page); |
| 1282 | |
| 1283 | /* |
| 1284 | * Make sure that we aren't completely killing |
| 1285 | * interactive performance. |
| 1286 | */ |
| 1287 | cond_resched(); |
| 1288 | } |
| 1289 | |
| 1290 | mmput(start_mm); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1291 | return retval; |
| 1292 | } |
| 1293 | |
| 1294 | /* |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1295 | * After a successful try_to_unuse, if no swap is now in use, we know |
| 1296 | * we can empty the mmlist. swap_lock must be held on entry and exit. |
| 1297 | * Note that mmlist_lock nests inside swap_lock, and an mm must be |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1298 | * added to the mmlist just after page_duplicate - before would be racy. |
| 1299 | */ |
| 1300 | static void drain_mmlist(void) |
| 1301 | { |
| 1302 | struct list_head *p, *next; |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1303 | unsigned int type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1304 | |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1305 | for (type = 0; type < nr_swapfiles; type++) |
| 1306 | if (swap_info[type]->inuse_pages) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1307 | return; |
| 1308 | spin_lock(&mmlist_lock); |
| 1309 | list_for_each_safe(p, next, &init_mm.mmlist) |
| 1310 | list_del_init(p); |
| 1311 | spin_unlock(&mmlist_lock); |
| 1312 | } |
| 1313 | |
| 1314 | /* |
| 1315 | * Use this swapdev's extent info to locate the (PAGE_SIZE) block which |
Lee Schermerhorn | d4906e1 | 2009-12-14 17:58:49 -0800 | [diff] [blame] | 1316 | * corresponds to page offset for the specified swap entry. |
| 1317 | * Note that the type of this function is sector_t, but it returns page offset |
| 1318 | * into the bdev, not sector offset. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1319 | */ |
Lee Schermerhorn | d4906e1 | 2009-12-14 17:58:49 -0800 | [diff] [blame] | 1320 | static sector_t map_swap_entry(swp_entry_t entry, struct block_device **bdev) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1321 | { |
Hugh Dickins | f29ad6a | 2009-12-14 17:58:40 -0800 | [diff] [blame] | 1322 | struct swap_info_struct *sis; |
| 1323 | struct swap_extent *start_se; |
| 1324 | struct swap_extent *se; |
| 1325 | pgoff_t offset; |
| 1326 | |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1327 | sis = swap_info[swp_type(entry)]; |
Hugh Dickins | f29ad6a | 2009-12-14 17:58:40 -0800 | [diff] [blame] | 1328 | *bdev = sis->bdev; |
| 1329 | |
| 1330 | offset = swp_offset(entry); |
| 1331 | start_se = sis->curr_swap_extent; |
| 1332 | se = start_se; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1333 | |
| 1334 | for ( ; ; ) { |
| 1335 | struct list_head *lh; |
| 1336 | |
| 1337 | if (se->start_page <= offset && |
| 1338 | offset < (se->start_page + se->nr_pages)) { |
| 1339 | return se->start_block + (offset - se->start_page); |
| 1340 | } |
Hugh Dickins | 11d3188 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 1341 | lh = se->list.next; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1342 | se = list_entry(lh, struct swap_extent, list); |
| 1343 | sis->curr_swap_extent = se; |
| 1344 | BUG_ON(se == start_se); /* It *must* be present */ |
| 1345 | } |
| 1346 | } |
| 1347 | |
| 1348 | /* |
Lee Schermerhorn | d4906e1 | 2009-12-14 17:58:49 -0800 | [diff] [blame] | 1349 | * Returns the page offset into bdev for the specified page's swap entry. |
| 1350 | */ |
| 1351 | sector_t map_swap_page(struct page *page, struct block_device **bdev) |
| 1352 | { |
| 1353 | swp_entry_t entry; |
| 1354 | entry.val = page_private(page); |
| 1355 | return map_swap_entry(entry, bdev); |
| 1356 | } |
| 1357 | |
| 1358 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1359 | * Free all of a swapdev's extent information |
| 1360 | */ |
| 1361 | static void destroy_swap_extents(struct swap_info_struct *sis) |
| 1362 | { |
Hugh Dickins | 9625a5f | 2009-12-14 17:58:42 -0800 | [diff] [blame] | 1363 | while (!list_empty(&sis->first_swap_extent.list)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1364 | struct swap_extent *se; |
| 1365 | |
Hugh Dickins | 9625a5f | 2009-12-14 17:58:42 -0800 | [diff] [blame] | 1366 | se = list_entry(sis->first_swap_extent.list.next, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1367 | struct swap_extent, list); |
| 1368 | list_del(&se->list); |
| 1369 | kfree(se); |
| 1370 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1371 | } |
| 1372 | |
| 1373 | /* |
| 1374 | * Add a block range (and the corresponding page range) into this swapdev's |
Hugh Dickins | 11d3188 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 1375 | * extent list. The extent list is kept sorted in page order. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1376 | * |
Hugh Dickins | 11d3188 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 1377 | * This function rather assumes that it is called in ascending page order. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1378 | */ |
| 1379 | static int |
| 1380 | add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, |
| 1381 | unsigned long nr_pages, sector_t start_block) |
| 1382 | { |
| 1383 | struct swap_extent *se; |
| 1384 | struct swap_extent *new_se; |
| 1385 | struct list_head *lh; |
| 1386 | |
Hugh Dickins | 9625a5f | 2009-12-14 17:58:42 -0800 | [diff] [blame] | 1387 | if (start_page == 0) { |
| 1388 | se = &sis->first_swap_extent; |
| 1389 | sis->curr_swap_extent = se; |
| 1390 | se->start_page = 0; |
| 1391 | se->nr_pages = nr_pages; |
| 1392 | se->start_block = start_block; |
| 1393 | return 1; |
| 1394 | } else { |
| 1395 | lh = sis->first_swap_extent.list.prev; /* Highest extent */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1396 | se = list_entry(lh, struct swap_extent, list); |
Hugh Dickins | 11d3188 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 1397 | BUG_ON(se->start_page + se->nr_pages != start_page); |
| 1398 | if (se->start_block + se->nr_pages == start_block) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1399 | /* Merge it */ |
| 1400 | se->nr_pages += nr_pages; |
| 1401 | return 0; |
| 1402 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1403 | } |
| 1404 | |
| 1405 | /* |
| 1406 | * No merge. Insert a new extent, preserving ordering. |
| 1407 | */ |
| 1408 | new_se = kmalloc(sizeof(*se), GFP_KERNEL); |
| 1409 | if (new_se == NULL) |
| 1410 | return -ENOMEM; |
| 1411 | new_se->start_page = start_page; |
| 1412 | new_se->nr_pages = nr_pages; |
| 1413 | new_se->start_block = start_block; |
| 1414 | |
Hugh Dickins | 9625a5f | 2009-12-14 17:58:42 -0800 | [diff] [blame] | 1415 | list_add_tail(&new_se->list, &sis->first_swap_extent.list); |
Hugh Dickins | 53092a7 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 1416 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1417 | } |
| 1418 | |
| 1419 | /* |
| 1420 | * A `swap extent' is a simple thing which maps a contiguous range of pages |
| 1421 | * onto a contiguous range of disk blocks. An ordered list of swap extents |
| 1422 | * is built at swapon time and is then used at swap_writepage/swap_readpage |
| 1423 | * time for locating where on disk a page belongs. |
| 1424 | * |
| 1425 | * If the swapfile is an S_ISBLK block device, a single extent is installed. |
| 1426 | * This is done so that the main operating code can treat S_ISBLK and S_ISREG |
| 1427 | * swap files identically. |
| 1428 | * |
| 1429 | * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap |
| 1430 | * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK |
| 1431 | * swapfiles are handled *identically* after swapon time. |
| 1432 | * |
| 1433 | * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks |
| 1434 | * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If |
| 1435 | * some stray blocks are found which do not fall within the PAGE_SIZE alignment |
| 1436 | * requirements, they are simply tossed out - we will never use those blocks |
| 1437 | * for swapping. |
| 1438 | * |
Hugh Dickins | b0d9bcd | 2005-09-03 15:54:31 -0700 | [diff] [blame] | 1439 | * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1440 | * prevents root from shooting her foot off by ftruncating an in-use swapfile, |
| 1441 | * which will scribble on the fs. |
| 1442 | * |
| 1443 | * The amount of disk space which a single swap extent represents varies. |
| 1444 | * Typically it is in the 1-4 megabyte range. So we can have hundreds of |
| 1445 | * extents in the list. To avoid much list walking, we cache the previous |
| 1446 | * search location in `curr_swap_extent', and start new searches from there. |
| 1447 | * This is extremely effective. The average number of iterations in |
| 1448 | * map_swap_page() has been measured at about 0.3 per page. - akpm. |
| 1449 | */ |
Hugh Dickins | 53092a7 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 1450 | static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1451 | { |
| 1452 | struct inode *inode; |
| 1453 | unsigned blocks_per_page; |
| 1454 | unsigned long page_no; |
| 1455 | unsigned blkbits; |
| 1456 | sector_t probe_block; |
| 1457 | sector_t last_block; |
Hugh Dickins | 53092a7 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 1458 | sector_t lowest_block = -1; |
| 1459 | sector_t highest_block = 0; |
| 1460 | int nr_extents = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1461 | int ret; |
| 1462 | |
| 1463 | inode = sis->swap_file->f_mapping->host; |
| 1464 | if (S_ISBLK(inode->i_mode)) { |
| 1465 | ret = add_swap_extent(sis, 0, sis->max, 0); |
Hugh Dickins | 53092a7 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 1466 | *span = sis->pages; |
Hugh Dickins | 9625a5f | 2009-12-14 17:58:42 -0800 | [diff] [blame] | 1467 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1468 | } |
| 1469 | |
| 1470 | blkbits = inode->i_blkbits; |
| 1471 | blocks_per_page = PAGE_SIZE >> blkbits; |
| 1472 | |
| 1473 | /* |
| 1474 | * Map all the blocks into the extent list. This code doesn't try |
| 1475 | * to be very smart. |
| 1476 | */ |
| 1477 | probe_block = 0; |
| 1478 | page_no = 0; |
| 1479 | last_block = i_size_read(inode) >> blkbits; |
| 1480 | while ((probe_block + blocks_per_page) <= last_block && |
| 1481 | page_no < sis->max) { |
| 1482 | unsigned block_in_page; |
| 1483 | sector_t first_block; |
| 1484 | |
| 1485 | first_block = bmap(inode, probe_block); |
| 1486 | if (first_block == 0) |
| 1487 | goto bad_bmap; |
| 1488 | |
| 1489 | /* |
| 1490 | * It must be PAGE_SIZE aligned on-disk |
| 1491 | */ |
| 1492 | if (first_block & (blocks_per_page - 1)) { |
| 1493 | probe_block++; |
| 1494 | goto reprobe; |
| 1495 | } |
| 1496 | |
| 1497 | for (block_in_page = 1; block_in_page < blocks_per_page; |
| 1498 | block_in_page++) { |
| 1499 | sector_t block; |
| 1500 | |
| 1501 | block = bmap(inode, probe_block + block_in_page); |
| 1502 | if (block == 0) |
| 1503 | goto bad_bmap; |
| 1504 | if (block != first_block + block_in_page) { |
| 1505 | /* Discontiguity */ |
| 1506 | probe_block++; |
| 1507 | goto reprobe; |
| 1508 | } |
| 1509 | } |
| 1510 | |
Hugh Dickins | 53092a7 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 1511 | first_block >>= (PAGE_SHIFT - blkbits); |
| 1512 | if (page_no) { /* exclude the header page */ |
| 1513 | if (first_block < lowest_block) |
| 1514 | lowest_block = first_block; |
| 1515 | if (first_block > highest_block) |
| 1516 | highest_block = first_block; |
| 1517 | } |
| 1518 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1519 | /* |
| 1520 | * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks |
| 1521 | */ |
Hugh Dickins | 53092a7 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 1522 | ret = add_swap_extent(sis, page_no, 1, first_block); |
| 1523 | if (ret < 0) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1524 | goto out; |
Hugh Dickins | 53092a7 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 1525 | nr_extents += ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1526 | page_no++; |
| 1527 | probe_block += blocks_per_page; |
| 1528 | reprobe: |
| 1529 | continue; |
| 1530 | } |
Hugh Dickins | 53092a7 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 1531 | ret = nr_extents; |
| 1532 | *span = 1 + highest_block - lowest_block; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1533 | if (page_no == 0) |
Hugh Dickins | e2244ec | 2005-09-03 15:54:32 -0700 | [diff] [blame] | 1534 | page_no = 1; /* force Empty message */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1535 | sis->max = page_no; |
Hugh Dickins | e2244ec | 2005-09-03 15:54:32 -0700 | [diff] [blame] | 1536 | sis->pages = page_no - 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1537 | sis->highest_bit = page_no - 1; |
Hugh Dickins | 9625a5f | 2009-12-14 17:58:42 -0800 | [diff] [blame] | 1538 | out: |
| 1539 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1540 | bad_bmap: |
| 1541 | printk(KERN_ERR "swapon: swapfile has holes\n"); |
| 1542 | ret = -EINVAL; |
Hugh Dickins | 9625a5f | 2009-12-14 17:58:42 -0800 | [diff] [blame] | 1543 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1544 | } |
| 1545 | |
Heiko Carstens | c4ea37c | 2009-01-14 14:14:28 +0100 | [diff] [blame] | 1546 | SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1547 | { |
Hugh Dickins | 73c34b6 | 2009-12-14 17:58:43 -0800 | [diff] [blame] | 1548 | struct swap_info_struct *p = NULL; |
Hugh Dickins | 8d69aae | 2009-12-14 17:58:45 -0800 | [diff] [blame] | 1549 | unsigned char *swap_map; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1550 | struct file *swap_file, *victim; |
| 1551 | struct address_space *mapping; |
| 1552 | struct inode *inode; |
Hugh Dickins | 73c34b6 | 2009-12-14 17:58:43 -0800 | [diff] [blame] | 1553 | char *pathname; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1554 | int i, type, prev; |
| 1555 | int err; |
Hugh Dickins | 886bb7e | 2009-01-06 14:39:48 -0800 | [diff] [blame] | 1556 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1557 | if (!capable(CAP_SYS_ADMIN)) |
| 1558 | return -EPERM; |
| 1559 | |
| 1560 | pathname = getname(specialfile); |
| 1561 | err = PTR_ERR(pathname); |
| 1562 | if (IS_ERR(pathname)) |
| 1563 | goto out; |
| 1564 | |
| 1565 | victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0); |
| 1566 | putname(pathname); |
| 1567 | err = PTR_ERR(victim); |
| 1568 | if (IS_ERR(victim)) |
| 1569 | goto out; |
| 1570 | |
| 1571 | mapping = victim->f_mapping; |
| 1572 | prev = -1; |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1573 | spin_lock(&swap_lock); |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1574 | for (type = swap_list.head; type >= 0; type = swap_info[type]->next) { |
| 1575 | p = swap_info[type]; |
Hugh Dickins | 22c6f8f | 2009-01-06 14:39:48 -0800 | [diff] [blame] | 1576 | if (p->flags & SWP_WRITEOK) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1577 | if (p->swap_file->f_mapping == mapping) |
| 1578 | break; |
| 1579 | } |
| 1580 | prev = type; |
| 1581 | } |
| 1582 | if (type < 0) { |
| 1583 | err = -EINVAL; |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1584 | spin_unlock(&swap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1585 | goto out_dput; |
| 1586 | } |
| 1587 | if (!security_vm_enough_memory(p->pages)) |
| 1588 | vm_unacct_memory(p->pages); |
| 1589 | else { |
| 1590 | err = -ENOMEM; |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1591 | spin_unlock(&swap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1592 | goto out_dput; |
| 1593 | } |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1594 | if (prev < 0) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1595 | swap_list.head = p->next; |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1596 | else |
| 1597 | swap_info[prev]->next = p->next; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1598 | if (type == swap_list.next) { |
| 1599 | /* just pick something that's safe... */ |
| 1600 | swap_list.next = swap_list.head; |
| 1601 | } |
Hugh Dickins | 78ecba0 | 2008-07-23 21:28:23 -0700 | [diff] [blame] | 1602 | if (p->prio < 0) { |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1603 | for (i = p->next; i >= 0; i = swap_info[i]->next) |
| 1604 | swap_info[i]->prio = p->prio--; |
Hugh Dickins | 78ecba0 | 2008-07-23 21:28:23 -0700 | [diff] [blame] | 1605 | least_priority++; |
| 1606 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1607 | nr_swap_pages -= p->pages; |
| 1608 | total_swap_pages -= p->pages; |
| 1609 | p->flags &= ~SWP_WRITEOK; |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1610 | spin_unlock(&swap_lock); |
Hugh Dickins | fb4f88d | 2005-09-03 15:54:37 -0700 | [diff] [blame] | 1611 | |
Hugh Dickins | 35451be | 2009-09-21 17:02:27 -0700 | [diff] [blame] | 1612 | current->flags |= PF_OOM_ORIGIN; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1613 | err = try_to_unuse(type); |
Hugh Dickins | 35451be | 2009-09-21 17:02:27 -0700 | [diff] [blame] | 1614 | current->flags &= ~PF_OOM_ORIGIN; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1615 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1616 | if (err) { |
| 1617 | /* re-insert swap space back into swap_list */ |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1618 | spin_lock(&swap_lock); |
Hugh Dickins | 78ecba0 | 2008-07-23 21:28:23 -0700 | [diff] [blame] | 1619 | if (p->prio < 0) |
| 1620 | p->prio = --least_priority; |
| 1621 | prev = -1; |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1622 | for (i = swap_list.head; i >= 0; i = swap_info[i]->next) { |
| 1623 | if (p->prio >= swap_info[i]->prio) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1624 | break; |
Hugh Dickins | 78ecba0 | 2008-07-23 21:28:23 -0700 | [diff] [blame] | 1625 | prev = i; |
| 1626 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1627 | p->next = i; |
| 1628 | if (prev < 0) |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1629 | swap_list.head = swap_list.next = type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1630 | else |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1631 | swap_info[prev]->next = type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1632 | nr_swap_pages += p->pages; |
| 1633 | total_swap_pages += p->pages; |
| 1634 | p->flags |= SWP_WRITEOK; |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1635 | spin_unlock(&swap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1636 | goto out_dput; |
| 1637 | } |
Hugh Dickins | 52b7efdb | 2005-09-03 15:54:39 -0700 | [diff] [blame] | 1638 | |
| 1639 | /* wait for any unplug function to finish */ |
| 1640 | down_write(&swap_unplug_sem); |
| 1641 | up_write(&swap_unplug_sem); |
| 1642 | |
Hugh Dickins | 4cd3bb1 | 2005-09-03 15:54:33 -0700 | [diff] [blame] | 1643 | destroy_swap_extents(p); |
Hugh Dickins | 570a335b | 2009-12-14 17:58:46 -0800 | [diff] [blame] | 1644 | if (p->flags & SWP_CONTINUED) |
| 1645 | free_swap_count_continuations(p); |
| 1646 | |
Ingo Molnar | fc0abb1 | 2006-01-18 17:42:33 -0800 | [diff] [blame] | 1647 | mutex_lock(&swapon_mutex); |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1648 | spin_lock(&swap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1649 | drain_mmlist(); |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1650 | |
| 1651 | /* wait for anyone still in scan_swap_map */ |
| 1652 | p->highest_bit = 0; /* cuts scans short */ |
| 1653 | while (p->flags >= SWP_SCANNING) { |
| 1654 | spin_unlock(&swap_lock); |
Nishanth Aravamudan | 13e4b57 | 2005-09-10 00:27:25 -0700 | [diff] [blame] | 1655 | schedule_timeout_uninterruptible(1); |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1656 | spin_lock(&swap_lock); |
| 1657 | } |
| 1658 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1659 | swap_file = p->swap_file; |
| 1660 | p->swap_file = NULL; |
| 1661 | p->max = 0; |
| 1662 | swap_map = p->swap_map; |
| 1663 | p->swap_map = NULL; |
| 1664 | p->flags = 0; |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1665 | spin_unlock(&swap_lock); |
Ingo Molnar | fc0abb1 | 2006-01-18 17:42:33 -0800 | [diff] [blame] | 1666 | mutex_unlock(&swapon_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1667 | vfree(swap_map); |
KAMEZAWA Hiroyuki | 27a7faa | 2009-01-07 18:07:58 -0800 | [diff] [blame] | 1668 | /* Destroy swap account informatin */ |
| 1669 | swap_cgroup_swapoff(type); |
| 1670 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1671 | inode = mapping->host; |
| 1672 | if (S_ISBLK(inode->i_mode)) { |
| 1673 | struct block_device *bdev = I_BDEV(inode); |
| 1674 | set_blocksize(bdev, p->old_block_size); |
| 1675 | bd_release(bdev); |
| 1676 | } else { |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 1677 | mutex_lock(&inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1678 | inode->i_flags &= ~S_SWAPFILE; |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 1679 | mutex_unlock(&inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1680 | } |
| 1681 | filp_close(swap_file, NULL); |
| 1682 | err = 0; |
| 1683 | |
| 1684 | out_dput: |
| 1685 | filp_close(victim, NULL); |
| 1686 | out: |
| 1687 | return err; |
| 1688 | } |
| 1689 | |
| 1690 | #ifdef CONFIG_PROC_FS |
| 1691 | /* iterator */ |
| 1692 | static void *swap_start(struct seq_file *swap, loff_t *pos) |
| 1693 | { |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1694 | struct swap_info_struct *si; |
| 1695 | int type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1696 | loff_t l = *pos; |
| 1697 | |
Ingo Molnar | fc0abb1 | 2006-01-18 17:42:33 -0800 | [diff] [blame] | 1698 | mutex_lock(&swapon_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1699 | |
Suleiman Souhlal | 881e4aa | 2006-12-06 20:32:28 -0800 | [diff] [blame] | 1700 | if (!l) |
| 1701 | return SEQ_START_TOKEN; |
| 1702 | |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1703 | for (type = 0; type < nr_swapfiles; type++) { |
| 1704 | smp_rmb(); /* read nr_swapfiles before swap_info[type] */ |
| 1705 | si = swap_info[type]; |
| 1706 | if (!(si->flags & SWP_USED) || !si->swap_map) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1707 | continue; |
Suleiman Souhlal | 881e4aa | 2006-12-06 20:32:28 -0800 | [diff] [blame] | 1708 | if (!--l) |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1709 | return si; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1710 | } |
| 1711 | |
| 1712 | return NULL; |
| 1713 | } |
| 1714 | |
| 1715 | static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) |
| 1716 | { |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1717 | struct swap_info_struct *si = v; |
| 1718 | int type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1719 | |
Suleiman Souhlal | 881e4aa | 2006-12-06 20:32:28 -0800 | [diff] [blame] | 1720 | if (v == SEQ_START_TOKEN) |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1721 | type = 0; |
| 1722 | else |
| 1723 | type = si->type + 1; |
Suleiman Souhlal | 881e4aa | 2006-12-06 20:32:28 -0800 | [diff] [blame] | 1724 | |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1725 | for (; type < nr_swapfiles; type++) { |
| 1726 | smp_rmb(); /* read nr_swapfiles before swap_info[type] */ |
| 1727 | si = swap_info[type]; |
| 1728 | if (!(si->flags & SWP_USED) || !si->swap_map) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1729 | continue; |
| 1730 | ++*pos; |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1731 | return si; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1732 | } |
| 1733 | |
| 1734 | return NULL; |
| 1735 | } |
| 1736 | |
| 1737 | static void swap_stop(struct seq_file *swap, void *v) |
| 1738 | { |
Ingo Molnar | fc0abb1 | 2006-01-18 17:42:33 -0800 | [diff] [blame] | 1739 | mutex_unlock(&swapon_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1740 | } |
| 1741 | |
| 1742 | static int swap_show(struct seq_file *swap, void *v) |
| 1743 | { |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1744 | struct swap_info_struct *si = v; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1745 | struct file *file; |
| 1746 | int len; |
| 1747 | |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1748 | if (si == SEQ_START_TOKEN) { |
Suleiman Souhlal | 881e4aa | 2006-12-06 20:32:28 -0800 | [diff] [blame] | 1749 | seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n"); |
| 1750 | return 0; |
| 1751 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1752 | |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1753 | file = si->swap_file; |
Jan Blunck | c32c2f6 | 2008-02-14 19:38:43 -0800 | [diff] [blame] | 1754 | len = seq_path(swap, &file->f_path, " \t\n\\"); |
Hugh Dickins | 6eb396d | 2005-09-03 15:54:35 -0700 | [diff] [blame] | 1755 | seq_printf(swap, "%*s%s\t%u\t%u\t%d\n", |
Hugh Dickins | 886bb7e | 2009-01-06 14:39:48 -0800 | [diff] [blame] | 1756 | len < 40 ? 40 - len : 1, " ", |
| 1757 | S_ISBLK(file->f_path.dentry->d_inode->i_mode) ? |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1758 | "partition" : "file\t", |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1759 | si->pages << (PAGE_SHIFT - 10), |
| 1760 | si->inuse_pages << (PAGE_SHIFT - 10), |
| 1761 | si->prio); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1762 | return 0; |
| 1763 | } |
| 1764 | |
Helge Deller | 15ad7cd | 2006-12-06 20:40:36 -0800 | [diff] [blame] | 1765 | static const struct seq_operations swaps_op = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1766 | .start = swap_start, |
| 1767 | .next = swap_next, |
| 1768 | .stop = swap_stop, |
| 1769 | .show = swap_show |
| 1770 | }; |
| 1771 | |
| 1772 | static int swaps_open(struct inode *inode, struct file *file) |
| 1773 | { |
| 1774 | return seq_open(file, &swaps_op); |
| 1775 | } |
| 1776 | |
Helge Deller | 15ad7cd | 2006-12-06 20:40:36 -0800 | [diff] [blame] | 1777 | static const struct file_operations proc_swaps_operations = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1778 | .open = swaps_open, |
| 1779 | .read = seq_read, |
| 1780 | .llseek = seq_lseek, |
| 1781 | .release = seq_release, |
| 1782 | }; |
| 1783 | |
| 1784 | static int __init procswaps_init(void) |
| 1785 | { |
Denis V. Lunev | 3d71f86 | 2008-04-29 01:02:13 -0700 | [diff] [blame] | 1786 | proc_create("swaps", 0, NULL, &proc_swaps_operations); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1787 | return 0; |
| 1788 | } |
| 1789 | __initcall(procswaps_init); |
| 1790 | #endif /* CONFIG_PROC_FS */ |
| 1791 | |
Jan Beulich | 1796316 | 2008-12-16 11:35:24 +0000 | [diff] [blame] | 1792 | #ifdef MAX_SWAPFILES_CHECK |
| 1793 | static int __init max_swapfiles_check(void) |
| 1794 | { |
| 1795 | MAX_SWAPFILES_CHECK(); |
| 1796 | return 0; |
| 1797 | } |
| 1798 | late_initcall(max_swapfiles_check); |
| 1799 | #endif |
| 1800 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1801 | /* |
| 1802 | * Written 01/25/92 by Simmule Turner, heavily changed by Linus. |
| 1803 | * |
| 1804 | * The swapon system call |
| 1805 | */ |
Heiko Carstens | c4ea37c | 2009-01-14 14:14:28 +0100 | [diff] [blame] | 1806 | SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1807 | { |
Hugh Dickins | 73c34b6 | 2009-12-14 17:58:43 -0800 | [diff] [blame] | 1808 | struct swap_info_struct *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1809 | char *name = NULL; |
| 1810 | struct block_device *bdev = NULL; |
| 1811 | struct file *swap_file = NULL; |
| 1812 | struct address_space *mapping; |
| 1813 | unsigned int type; |
| 1814 | int i, prev; |
| 1815 | int error; |
Hugh Dickins | ad2bd7e | 2010-03-05 13:42:12 -0800 | [diff] [blame] | 1816 | union swap_header *swap_header; |
| 1817 | unsigned int nr_good_pages; |
Hugh Dickins | 6eb396d | 2005-09-03 15:54:35 -0700 | [diff] [blame] | 1818 | int nr_extents = 0; |
Hugh Dickins | 53092a7 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 1819 | sector_t span; |
Hugh Dickins | ad2bd7e | 2010-03-05 13:42:12 -0800 | [diff] [blame] | 1820 | unsigned long maxpages; |
Hugh Dickins | 73fd874 | 2009-01-06 14:39:47 -0800 | [diff] [blame] | 1821 | unsigned long swapfilepages; |
Hugh Dickins | 8d69aae | 2009-12-14 17:58:45 -0800 | [diff] [blame] | 1822 | unsigned char *swap_map = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1823 | struct page *page = NULL; |
| 1824 | struct inode *inode = NULL; |
| 1825 | int did_down = 0; |
| 1826 | |
| 1827 | if (!capable(CAP_SYS_ADMIN)) |
| 1828 | return -EPERM; |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1829 | |
| 1830 | p = kzalloc(sizeof(*p), GFP_KERNEL); |
| 1831 | if (!p) |
| 1832 | return -ENOMEM; |
| 1833 | |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1834 | spin_lock(&swap_lock); |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1835 | for (type = 0; type < nr_swapfiles; type++) { |
| 1836 | if (!(swap_info[type]->flags & SWP_USED)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1837 | break; |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1838 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1839 | error = -EPERM; |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 1840 | if (type >= MAX_SWAPFILES) { |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1841 | spin_unlock(&swap_lock); |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1842 | kfree(p); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1843 | goto out; |
| 1844 | } |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1845 | if (type >= nr_swapfiles) { |
| 1846 | p->type = type; |
| 1847 | swap_info[type] = p; |
| 1848 | /* |
| 1849 | * Write swap_info[type] before nr_swapfiles, in case a |
| 1850 | * racing procfs swap_start() or swap_next() is reading them. |
| 1851 | * (We never shrink nr_swapfiles, we never free this entry.) |
| 1852 | */ |
| 1853 | smp_wmb(); |
| 1854 | nr_swapfiles++; |
| 1855 | } else { |
| 1856 | kfree(p); |
| 1857 | p = swap_info[type]; |
| 1858 | /* |
| 1859 | * Do not memset this entry: a racing procfs swap_next() |
| 1860 | * would be relying on p->type to remain valid. |
| 1861 | */ |
| 1862 | } |
Hugh Dickins | 9625a5f | 2009-12-14 17:58:42 -0800 | [diff] [blame] | 1863 | INIT_LIST_HEAD(&p->first_swap_extent.list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1864 | p->flags = SWP_USED; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1865 | p->next = -1; |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 1866 | spin_unlock(&swap_lock); |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1867 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1868 | name = getname(specialfile); |
| 1869 | error = PTR_ERR(name); |
| 1870 | if (IS_ERR(name)) { |
| 1871 | name = NULL; |
| 1872 | goto bad_swap_2; |
| 1873 | } |
| 1874 | swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0); |
| 1875 | error = PTR_ERR(swap_file); |
| 1876 | if (IS_ERR(swap_file)) { |
| 1877 | swap_file = NULL; |
| 1878 | goto bad_swap_2; |
| 1879 | } |
| 1880 | |
| 1881 | p->swap_file = swap_file; |
| 1882 | mapping = swap_file->f_mapping; |
| 1883 | inode = mapping->host; |
| 1884 | |
| 1885 | error = -EBUSY; |
| 1886 | for (i = 0; i < nr_swapfiles; i++) { |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1887 | struct swap_info_struct *q = swap_info[i]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1888 | |
| 1889 | if (i == type || !q->swap_file) |
| 1890 | continue; |
| 1891 | if (mapping == q->swap_file->f_mapping) |
| 1892 | goto bad_swap; |
| 1893 | } |
| 1894 | |
| 1895 | error = -EINVAL; |
| 1896 | if (S_ISBLK(inode->i_mode)) { |
| 1897 | bdev = I_BDEV(inode); |
| 1898 | error = bd_claim(bdev, sys_swapon); |
| 1899 | if (error < 0) { |
| 1900 | bdev = NULL; |
Rob Landley | f7b3a43 | 2005-09-22 21:44:27 -0700 | [diff] [blame] | 1901 | error = -EINVAL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1902 | goto bad_swap; |
| 1903 | } |
| 1904 | p->old_block_size = block_size(bdev); |
| 1905 | error = set_blocksize(bdev, PAGE_SIZE); |
| 1906 | if (error < 0) |
| 1907 | goto bad_swap; |
| 1908 | p->bdev = bdev; |
Nitin Gupta | b272564 | 2010-05-17 11:02:42 +0530 | [diff] [blame] | 1909 | p->flags |= SWP_BLKDEV; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1910 | } else if (S_ISREG(inode->i_mode)) { |
| 1911 | p->bdev = inode->i_sb->s_bdev; |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 1912 | mutex_lock(&inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1913 | did_down = 1; |
| 1914 | if (IS_SWAPFILE(inode)) { |
| 1915 | error = -EBUSY; |
| 1916 | goto bad_swap; |
| 1917 | } |
| 1918 | } else { |
| 1919 | goto bad_swap; |
| 1920 | } |
| 1921 | |
Hugh Dickins | 73fd874 | 2009-01-06 14:39:47 -0800 | [diff] [blame] | 1922 | swapfilepages = i_size_read(inode) >> PAGE_SHIFT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1923 | |
| 1924 | /* |
| 1925 | * Read the swap header. |
| 1926 | */ |
| 1927 | if (!mapping->a_ops->readpage) { |
| 1928 | error = -EINVAL; |
| 1929 | goto bad_swap; |
| 1930 | } |
Pekka Enberg | 090d2b1 | 2006-06-23 02:05:08 -0700 | [diff] [blame] | 1931 | page = read_mapping_page(mapping, 0, swap_file); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1932 | if (IS_ERR(page)) { |
| 1933 | error = PTR_ERR(page); |
| 1934 | goto bad_swap; |
| 1935 | } |
Hugh Dickins | 81e3397 | 2009-01-06 14:39:49 -0800 | [diff] [blame] | 1936 | swap_header = kmap(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1937 | |
Hugh Dickins | 81e3397 | 2009-01-06 14:39:49 -0800 | [diff] [blame] | 1938 | if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) { |
Jesper Juhl | e97a311 | 2006-01-11 01:50:28 +0100 | [diff] [blame] | 1939 | printk(KERN_ERR "Unable to find swap-space signature\n"); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1940 | error = -EINVAL; |
| 1941 | goto bad_swap; |
| 1942 | } |
Hugh Dickins | 886bb7e | 2009-01-06 14:39:48 -0800 | [diff] [blame] | 1943 | |
Hugh Dickins | 81e3397 | 2009-01-06 14:39:49 -0800 | [diff] [blame] | 1944 | /* swap partition endianess hack... */ |
| 1945 | if (swab32(swap_header->info.version) == 1) { |
| 1946 | swab32s(&swap_header->info.version); |
| 1947 | swab32s(&swap_header->info.last_page); |
| 1948 | swab32s(&swap_header->info.nr_badpages); |
| 1949 | for (i = 0; i < swap_header->info.nr_badpages; i++) |
| 1950 | swab32s(&swap_header->info.badpages[i]); |
| 1951 | } |
| 1952 | /* Check the swap header's sub-version */ |
| 1953 | if (swap_header->info.version != 1) { |
| 1954 | printk(KERN_WARNING |
| 1955 | "Unable to handle swap header version %d\n", |
| 1956 | swap_header->info.version); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1957 | error = -EINVAL; |
| 1958 | goto bad_swap; |
Hugh Dickins | 81e3397 | 2009-01-06 14:39:49 -0800 | [diff] [blame] | 1959 | } |
| 1960 | |
| 1961 | p->lowest_bit = 1; |
| 1962 | p->cluster_next = 1; |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 1963 | p->cluster_nr = 0; |
Hugh Dickins | 81e3397 | 2009-01-06 14:39:49 -0800 | [diff] [blame] | 1964 | |
| 1965 | /* |
| 1966 | * Find out how many pages are allowed for a single swap |
| 1967 | * device. There are two limiting factors: 1) the number of |
| 1968 | * bits for the swap offset in the swp_entry_t type and |
| 1969 | * 2) the number of bits in the a swap pte as defined by |
| 1970 | * the different architectures. In order to find the |
| 1971 | * largest possible bit mask a swap entry with swap type 0 |
| 1972 | * and swap offset ~0UL is created, encoded to a swap pte, |
| 1973 | * decoded to a swp_entry_t again and finally the swap |
| 1974 | * offset is extracted. This will mask all the bits from |
| 1975 | * the initial ~0UL mask that can't be encoded in either |
| 1976 | * the swp_entry_t or the architecture definition of a |
| 1977 | * swap pte. |
| 1978 | */ |
| 1979 | maxpages = swp_offset(pte_to_swp_entry( |
Hugh Dickins | ad2bd7e | 2010-03-05 13:42:12 -0800 | [diff] [blame] | 1980 | swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1; |
| 1981 | if (maxpages > swap_header->info.last_page) { |
| 1982 | maxpages = swap_header->info.last_page + 1; |
| 1983 | /* p->max is an unsigned int: don't overflow it */ |
| 1984 | if ((unsigned int)maxpages == 0) |
| 1985 | maxpages = UINT_MAX; |
| 1986 | } |
Hugh Dickins | 81e3397 | 2009-01-06 14:39:49 -0800 | [diff] [blame] | 1987 | p->highest_bit = maxpages - 1; |
| 1988 | |
| 1989 | error = -EINVAL; |
| 1990 | if (!maxpages) |
| 1991 | goto bad_swap; |
| 1992 | if (swapfilepages && maxpages > swapfilepages) { |
| 1993 | printk(KERN_WARNING |
| 1994 | "Swap area shorter than signature indicates\n"); |
| 1995 | goto bad_swap; |
| 1996 | } |
| 1997 | if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) |
| 1998 | goto bad_swap; |
| 1999 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
| 2000 | goto bad_swap; |
| 2001 | |
| 2002 | /* OK, set up the swap map and apply the bad block list */ |
Hugh Dickins | 8d69aae | 2009-12-14 17:58:45 -0800 | [diff] [blame] | 2003 | swap_map = vmalloc(maxpages); |
Hugh Dickins | 81e3397 | 2009-01-06 14:39:49 -0800 | [diff] [blame] | 2004 | if (!swap_map) { |
| 2005 | error = -ENOMEM; |
| 2006 | goto bad_swap; |
| 2007 | } |
| 2008 | |
Hugh Dickins | 8d69aae | 2009-12-14 17:58:45 -0800 | [diff] [blame] | 2009 | memset(swap_map, 0, maxpages); |
Hugh Dickins | ad2bd7e | 2010-03-05 13:42:12 -0800 | [diff] [blame] | 2010 | nr_good_pages = maxpages - 1; /* omit header page */ |
| 2011 | |
Hugh Dickins | 81e3397 | 2009-01-06 14:39:49 -0800 | [diff] [blame] | 2012 | for (i = 0; i < swap_header->info.nr_badpages; i++) { |
Hugh Dickins | ad2bd7e | 2010-03-05 13:42:12 -0800 | [diff] [blame] | 2013 | unsigned int page_nr = swap_header->info.badpages[i]; |
| 2014 | if (page_nr == 0 || page_nr > swap_header->info.last_page) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2015 | error = -EINVAL; |
| 2016 | goto bad_swap; |
| 2017 | } |
Hugh Dickins | ad2bd7e | 2010-03-05 13:42:12 -0800 | [diff] [blame] | 2018 | if (page_nr < maxpages) { |
| 2019 | swap_map[page_nr] = SWAP_MAP_BAD; |
| 2020 | nr_good_pages--; |
| 2021 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2022 | } |
KAMEZAWA Hiroyuki | 27a7faa | 2009-01-07 18:07:58 -0800 | [diff] [blame] | 2023 | |
| 2024 | error = swap_cgroup_swapon(type, maxpages); |
| 2025 | if (error) |
| 2026 | goto bad_swap; |
| 2027 | |
Hugh Dickins | e2244ec | 2005-09-03 15:54:32 -0700 | [diff] [blame] | 2028 | if (nr_good_pages) { |
Hugh Dickins | 78ecba0 | 2008-07-23 21:28:23 -0700 | [diff] [blame] | 2029 | swap_map[0] = SWAP_MAP_BAD; |
Hugh Dickins | e2244ec | 2005-09-03 15:54:32 -0700 | [diff] [blame] | 2030 | p->max = maxpages; |
| 2031 | p->pages = nr_good_pages; |
Hugh Dickins | 53092a7 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 2032 | nr_extents = setup_swap_extents(p, &span); |
| 2033 | if (nr_extents < 0) { |
| 2034 | error = nr_extents; |
Hugh Dickins | e2244ec | 2005-09-03 15:54:32 -0700 | [diff] [blame] | 2035 | goto bad_swap; |
Hugh Dickins | 53092a7 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 2036 | } |
Hugh Dickins | e2244ec | 2005-09-03 15:54:32 -0700 | [diff] [blame] | 2037 | nr_good_pages = p->pages; |
| 2038 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2039 | if (!nr_good_pages) { |
| 2040 | printk(KERN_WARNING "Empty swap-file\n"); |
| 2041 | error = -EINVAL; |
| 2042 | goto bad_swap; |
| 2043 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2044 | |
Suresh Jayaraman | 3bd0f0c | 2009-09-30 10:53:48 +0200 | [diff] [blame] | 2045 | if (p->bdev) { |
| 2046 | if (blk_queue_nonrot(bdev_get_queue(p->bdev))) { |
| 2047 | p->flags |= SWP_SOLIDSTATE; |
| 2048 | p->cluster_next = 1 + (random32() % p->highest_bit); |
| 2049 | } |
Hugh Dickins | 3399446 | 2010-09-09 16:38:11 -0700 | [diff] [blame] | 2050 | if (discard_swap(p) == 0 && (swap_flags & SWAP_FLAG_DISCARD)) |
Suresh Jayaraman | 3bd0f0c | 2009-09-30 10:53:48 +0200 | [diff] [blame] | 2051 | p->flags |= SWP_DISCARDABLE; |
Hugh Dickins | 20137a4 | 2009-01-06 14:39:54 -0800 | [diff] [blame] | 2052 | } |
Hugh Dickins | 6a6ba83 | 2009-01-06 14:39:51 -0800 | [diff] [blame] | 2053 | |
Ingo Molnar | fc0abb1 | 2006-01-18 17:42:33 -0800 | [diff] [blame] | 2054 | mutex_lock(&swapon_mutex); |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 2055 | spin_lock(&swap_lock); |
Hugh Dickins | 78ecba0 | 2008-07-23 21:28:23 -0700 | [diff] [blame] | 2056 | if (swap_flags & SWAP_FLAG_PREFER) |
| 2057 | p->prio = |
| 2058 | (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT; |
| 2059 | else |
| 2060 | p->prio = --least_priority; |
| 2061 | p->swap_map = swap_map; |
Hugh Dickins | 22c6f8f | 2009-01-06 14:39:48 -0800 | [diff] [blame] | 2062 | p->flags |= SWP_WRITEOK; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2063 | nr_swap_pages += nr_good_pages; |
| 2064 | total_swap_pages += nr_good_pages; |
Hugh Dickins | 53092a7 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 2065 | |
Hugh Dickins | 6eb396d | 2005-09-03 15:54:35 -0700 | [diff] [blame] | 2066 | printk(KERN_INFO "Adding %uk swap on %s. " |
Hugh Dickins | 20137a4 | 2009-01-06 14:39:54 -0800 | [diff] [blame] | 2067 | "Priority:%d extents:%d across:%lluk %s%s\n", |
Hugh Dickins | 53092a7 | 2005-09-03 15:54:34 -0700 | [diff] [blame] | 2068 | nr_good_pages<<(PAGE_SHIFT-10), name, p->prio, |
Hugh Dickins | 6a6ba83 | 2009-01-06 14:39:51 -0800 | [diff] [blame] | 2069 | nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10), |
Hugh Dickins | 20137a4 | 2009-01-06 14:39:54 -0800 | [diff] [blame] | 2070 | (p->flags & SWP_SOLIDSTATE) ? "SS" : "", |
| 2071 | (p->flags & SWP_DISCARDABLE) ? "D" : ""); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2072 | |
| 2073 | /* insert swap space into swap_list: */ |
| 2074 | prev = -1; |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 2075 | for (i = swap_list.head; i >= 0; i = swap_info[i]->next) { |
| 2076 | if (p->prio >= swap_info[i]->prio) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2077 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2078 | prev = i; |
| 2079 | } |
| 2080 | p->next = i; |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 2081 | if (prev < 0) |
| 2082 | swap_list.head = swap_list.next = type; |
| 2083 | else |
| 2084 | swap_info[prev]->next = type; |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 2085 | spin_unlock(&swap_lock); |
Ingo Molnar | fc0abb1 | 2006-01-18 17:42:33 -0800 | [diff] [blame] | 2086 | mutex_unlock(&swapon_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2087 | error = 0; |
| 2088 | goto out; |
| 2089 | bad_swap: |
| 2090 | if (bdev) { |
| 2091 | set_blocksize(bdev, p->old_block_size); |
| 2092 | bd_release(bdev); |
| 2093 | } |
Hugh Dickins | 4cd3bb1 | 2005-09-03 15:54:33 -0700 | [diff] [blame] | 2094 | destroy_swap_extents(p); |
KAMEZAWA Hiroyuki | 27a7faa | 2009-01-07 18:07:58 -0800 | [diff] [blame] | 2095 | swap_cgroup_swapoff(type); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2096 | bad_swap_2: |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 2097 | spin_lock(&swap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2098 | p->swap_file = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2099 | p->flags = 0; |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 2100 | spin_unlock(&swap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2101 | vfree(swap_map); |
| 2102 | if (swap_file) |
| 2103 | filp_close(swap_file, NULL); |
| 2104 | out: |
| 2105 | if (page && !IS_ERR(page)) { |
| 2106 | kunmap(page); |
| 2107 | page_cache_release(page); |
| 2108 | } |
| 2109 | if (name) |
| 2110 | putname(name); |
| 2111 | if (did_down) { |
| 2112 | if (!error) |
| 2113 | inode->i_flags |= S_SWAPFILE; |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 2114 | mutex_unlock(&inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2115 | } |
| 2116 | return error; |
| 2117 | } |
| 2118 | |
| 2119 | void si_swapinfo(struct sysinfo *val) |
| 2120 | { |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 2121 | unsigned int type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2122 | unsigned long nr_to_be_unused = 0; |
| 2123 | |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 2124 | spin_lock(&swap_lock); |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 2125 | for (type = 0; type < nr_swapfiles; type++) { |
| 2126 | struct swap_info_struct *si = swap_info[type]; |
| 2127 | |
| 2128 | if ((si->flags & SWP_USED) && !(si->flags & SWP_WRITEOK)) |
| 2129 | nr_to_be_unused += si->inuse_pages; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2130 | } |
| 2131 | val->freeswap = nr_swap_pages + nr_to_be_unused; |
| 2132 | val->totalswap = total_swap_pages + nr_to_be_unused; |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 2133 | spin_unlock(&swap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2134 | } |
| 2135 | |
| 2136 | /* |
| 2137 | * Verify that a swap entry is valid and increment its swap map count. |
| 2138 | * |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2139 | * Returns error code in following case. |
| 2140 | * - success -> 0 |
| 2141 | * - swp_entry is invalid -> EINVAL |
| 2142 | * - swp_entry is migration entry -> EINVAL |
| 2143 | * - swap-cache reference is requested but there is already one. -> EEXIST |
| 2144 | * - swap-cache reference is requested but the entry is not used. -> ENOENT |
Hugh Dickins | 570a335b | 2009-12-14 17:58:46 -0800 | [diff] [blame] | 2145 | * - swap-mapped reference requested but needs continued swap count. -> ENOMEM |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2146 | */ |
Hugh Dickins | 8d69aae | 2009-12-14 17:58:45 -0800 | [diff] [blame] | 2147 | static int __swap_duplicate(swp_entry_t entry, unsigned char usage) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2148 | { |
Hugh Dickins | 73c34b6 | 2009-12-14 17:58:43 -0800 | [diff] [blame] | 2149 | struct swap_info_struct *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2150 | unsigned long offset, type; |
Hugh Dickins | 8d69aae | 2009-12-14 17:58:45 -0800 | [diff] [blame] | 2151 | unsigned char count; |
| 2152 | unsigned char has_cache; |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 2153 | int err = -EINVAL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2154 | |
Andi Kleen | a7420aa | 2009-09-16 11:50:05 +0200 | [diff] [blame] | 2155 | if (non_swap_entry(entry)) |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 2156 | goto out; |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 2157 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2158 | type = swp_type(entry); |
| 2159 | if (type >= nr_swapfiles) |
| 2160 | goto bad_file; |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 2161 | p = swap_info[type]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2162 | offset = swp_offset(entry); |
| 2163 | |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 2164 | spin_lock(&swap_lock); |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2165 | if (unlikely(offset >= p->max)) |
| 2166 | goto unlock_out; |
| 2167 | |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 2168 | count = p->swap_map[offset]; |
| 2169 | has_cache = count & SWAP_HAS_CACHE; |
| 2170 | count &= ~SWAP_HAS_CACHE; |
| 2171 | err = 0; |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2172 | |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 2173 | if (usage == SWAP_HAS_CACHE) { |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2174 | |
| 2175 | /* set SWAP_HAS_CACHE if there is no cache and entry is used */ |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 2176 | if (!has_cache && count) |
| 2177 | has_cache = SWAP_HAS_CACHE; |
| 2178 | else if (has_cache) /* someone else added cache */ |
| 2179 | err = -EEXIST; |
| 2180 | else /* no users remaining */ |
| 2181 | err = -ENOENT; |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2182 | |
| 2183 | } else if (count || has_cache) { |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 2184 | |
Hugh Dickins | 570a335b | 2009-12-14 17:58:46 -0800 | [diff] [blame] | 2185 | if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX) |
| 2186 | count += usage; |
| 2187 | else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX) |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 2188 | err = -EINVAL; |
Hugh Dickins | 570a335b | 2009-12-14 17:58:46 -0800 | [diff] [blame] | 2189 | else if (swap_count_continued(p, offset, count)) |
| 2190 | count = COUNT_CONTINUED; |
| 2191 | else |
| 2192 | err = -ENOMEM; |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2193 | } else |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 2194 | err = -ENOENT; /* unused swap entry */ |
| 2195 | |
| 2196 | p->swap_map[offset] = count | has_cache; |
| 2197 | |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2198 | unlock_out: |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 2199 | spin_unlock(&swap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2200 | out: |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 2201 | return err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2202 | |
| 2203 | bad_file: |
| 2204 | printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val); |
| 2205 | goto out; |
| 2206 | } |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 2207 | |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2208 | /* |
Hugh Dickins | aaa4686 | 2009-12-14 17:58:47 -0800 | [diff] [blame] | 2209 | * Help swapoff by noting that swap entry belongs to shmem/tmpfs |
| 2210 | * (in which case its reference count is never incremented). |
| 2211 | */ |
| 2212 | void swap_shmem_alloc(swp_entry_t entry) |
| 2213 | { |
| 2214 | __swap_duplicate(entry, SWAP_MAP_SHMEM); |
| 2215 | } |
| 2216 | |
| 2217 | /* |
Hugh Dickins | 08259d5 | 2010-03-05 13:42:25 -0800 | [diff] [blame] | 2218 | * Increase reference count of swap entry by 1. |
| 2219 | * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required |
| 2220 | * but could not be atomically allocated. Returns 0, just as if it succeeded, |
| 2221 | * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which |
| 2222 | * might occur if a page table entry has got corrupted. |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2223 | */ |
Hugh Dickins | 570a335b | 2009-12-14 17:58:46 -0800 | [diff] [blame] | 2224 | int swap_duplicate(swp_entry_t entry) |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2225 | { |
Hugh Dickins | 570a335b | 2009-12-14 17:58:46 -0800 | [diff] [blame] | 2226 | int err = 0; |
| 2227 | |
| 2228 | while (!err && __swap_duplicate(entry, 1) == -ENOMEM) |
| 2229 | err = add_swap_count_continuation(entry, GFP_ATOMIC); |
| 2230 | return err; |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2231 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2232 | |
KAMEZAWA Hiroyuki | cb4b86b | 2009-06-16 15:32:52 -0700 | [diff] [blame] | 2233 | /* |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2234 | * @entry: swap entry for which we allocate swap cache. |
| 2235 | * |
Hugh Dickins | 73c34b6 | 2009-12-14 17:58:43 -0800 | [diff] [blame] | 2236 | * Called when allocating swap cache for existing swap entry, |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2237 | * This can return error codes. Returns 0 at success. |
| 2238 | * -EBUSY means there is a swap cache. |
| 2239 | * Note: return code is different from swap_duplicate(). |
KAMEZAWA Hiroyuki | cb4b86b | 2009-06-16 15:32:52 -0700 | [diff] [blame] | 2240 | */ |
| 2241 | int swapcache_prepare(swp_entry_t entry) |
| 2242 | { |
Hugh Dickins | 253d553 | 2009-12-14 17:58:44 -0800 | [diff] [blame] | 2243 | return __swap_duplicate(entry, SWAP_HAS_CACHE); |
KAMEZAWA Hiroyuki | cb4b86b | 2009-06-16 15:32:52 -0700 | [diff] [blame] | 2244 | } |
| 2245 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2246 | /* |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 2247 | * swap_lock prevents swap_map being freed. Don't grab an extra |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2248 | * reference on the swaphandle, it doesn't matter if it becomes unused. |
| 2249 | */ |
| 2250 | int valid_swaphandles(swp_entry_t entry, unsigned long *offset) |
| 2251 | { |
Hugh Dickins | 8952898 | 2008-02-04 22:28:45 -0800 | [diff] [blame] | 2252 | struct swap_info_struct *si; |
Hugh Dickins | 3f9e794 | 2006-09-29 02:01:26 -0700 | [diff] [blame] | 2253 | int our_page_cluster = page_cluster; |
Hugh Dickins | 8952898 | 2008-02-04 22:28:45 -0800 | [diff] [blame] | 2254 | pgoff_t target, toff; |
| 2255 | pgoff_t base, end; |
| 2256 | int nr_pages = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2257 | |
Hugh Dickins | 3f9e794 | 2006-09-29 02:01:26 -0700 | [diff] [blame] | 2258 | if (!our_page_cluster) /* no readahead */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2259 | return 0; |
Hugh Dickins | 8952898 | 2008-02-04 22:28:45 -0800 | [diff] [blame] | 2260 | |
Hugh Dickins | efa90a9 | 2009-12-14 17:58:41 -0800 | [diff] [blame] | 2261 | si = swap_info[swp_type(entry)]; |
Hugh Dickins | 8952898 | 2008-02-04 22:28:45 -0800 | [diff] [blame] | 2262 | target = swp_offset(entry); |
| 2263 | base = (target >> our_page_cluster) << our_page_cluster; |
| 2264 | end = base + (1 << our_page_cluster); |
| 2265 | if (!base) /* first page is swap header */ |
| 2266 | base++; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2267 | |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 2268 | spin_lock(&swap_lock); |
Hugh Dickins | 8952898 | 2008-02-04 22:28:45 -0800 | [diff] [blame] | 2269 | if (end > si->max) /* don't go beyond end of map */ |
| 2270 | end = si->max; |
| 2271 | |
| 2272 | /* Count contiguous allocated slots above our target */ |
| 2273 | for (toff = target; ++toff < end; nr_pages++) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2274 | /* Don't read in free or bad pages */ |
Hugh Dickins | 8952898 | 2008-02-04 22:28:45 -0800 | [diff] [blame] | 2275 | if (!si->swap_map[toff]) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2276 | break; |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2277 | if (swap_count(si->swap_map[toff]) == SWAP_MAP_BAD) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2278 | break; |
Hugh Dickins | 8952898 | 2008-02-04 22:28:45 -0800 | [diff] [blame] | 2279 | } |
| 2280 | /* Count contiguous allocated slots below our target */ |
| 2281 | for (toff = target; --toff >= base; nr_pages++) { |
| 2282 | /* Don't read in free or bad pages */ |
| 2283 | if (!si->swap_map[toff]) |
| 2284 | break; |
KAMEZAWA Hiroyuki | 355cfa7 | 2009-06-16 15:32:53 -0700 | [diff] [blame] | 2285 | if (swap_count(si->swap_map[toff]) == SWAP_MAP_BAD) |
Hugh Dickins | 8952898 | 2008-02-04 22:28:45 -0800 | [diff] [blame] | 2286 | break; |
| 2287 | } |
Hugh Dickins | 5d337b9 | 2005-09-03 15:54:41 -0700 | [diff] [blame] | 2288 | spin_unlock(&swap_lock); |
Hugh Dickins | 8952898 | 2008-02-04 22:28:45 -0800 | [diff] [blame] | 2289 | |
| 2290 | /* |
| 2291 | * Indicate starting offset, and return number of pages to get: |
| 2292 | * if only 1, say 0, since there's then no readahead to be done. |
| 2293 | */ |
| 2294 | *offset = ++toff; |
| 2295 | return nr_pages? ++nr_pages: 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2296 | } |
Hugh Dickins | 570a335b | 2009-12-14 17:58:46 -0800 | [diff] [blame] | 2297 | |
| 2298 | /* |
| 2299 | * add_swap_count_continuation - called when a swap count is duplicated |
| 2300 | * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's |
| 2301 | * page of the original vmalloc'ed swap_map, to hold the continuation count |
| 2302 | * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called |
| 2303 | * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc. |
| 2304 | * |
| 2305 | * These continuation pages are seldom referenced: the common paths all work |
| 2306 | * on the original swap_map, only referring to a continuation page when the |
| 2307 | * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX. |
| 2308 | * |
| 2309 | * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding |
| 2310 | * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL) |
| 2311 | * can be called after dropping locks. |
| 2312 | */ |
| 2313 | int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask) |
| 2314 | { |
| 2315 | struct swap_info_struct *si; |
| 2316 | struct page *head; |
| 2317 | struct page *page; |
| 2318 | struct page *list_page; |
| 2319 | pgoff_t offset; |
| 2320 | unsigned char count; |
| 2321 | |
| 2322 | /* |
| 2323 | * When debugging, it's easier to use __GFP_ZERO here; but it's better |
| 2324 | * for latency not to zero a page while GFP_ATOMIC and holding locks. |
| 2325 | */ |
| 2326 | page = alloc_page(gfp_mask | __GFP_HIGHMEM); |
| 2327 | |
| 2328 | si = swap_info_get(entry); |
| 2329 | if (!si) { |
| 2330 | /* |
| 2331 | * An acceptable race has occurred since the failing |
| 2332 | * __swap_duplicate(): the swap entry has been freed, |
| 2333 | * perhaps even the whole swap_map cleared for swapoff. |
| 2334 | */ |
| 2335 | goto outer; |
| 2336 | } |
| 2337 | |
| 2338 | offset = swp_offset(entry); |
| 2339 | count = si->swap_map[offset] & ~SWAP_HAS_CACHE; |
| 2340 | |
| 2341 | if ((count & ~COUNT_CONTINUED) != SWAP_MAP_MAX) { |
| 2342 | /* |
| 2343 | * The higher the swap count, the more likely it is that tasks |
| 2344 | * will race to add swap count continuation: we need to avoid |
| 2345 | * over-provisioning. |
| 2346 | */ |
| 2347 | goto out; |
| 2348 | } |
| 2349 | |
| 2350 | if (!page) { |
| 2351 | spin_unlock(&swap_lock); |
| 2352 | return -ENOMEM; |
| 2353 | } |
| 2354 | |
| 2355 | /* |
| 2356 | * We are fortunate that although vmalloc_to_page uses pte_offset_map, |
| 2357 | * no architecture is using highmem pages for kernel pagetables: so it |
| 2358 | * will not corrupt the GFP_ATOMIC caller's atomic pagetable kmaps. |
| 2359 | */ |
| 2360 | head = vmalloc_to_page(si->swap_map + offset); |
| 2361 | offset &= ~PAGE_MASK; |
| 2362 | |
| 2363 | /* |
| 2364 | * Page allocation does not initialize the page's lru field, |
| 2365 | * but it does always reset its private field. |
| 2366 | */ |
| 2367 | if (!page_private(head)) { |
| 2368 | BUG_ON(count & COUNT_CONTINUED); |
| 2369 | INIT_LIST_HEAD(&head->lru); |
| 2370 | set_page_private(head, SWP_CONTINUED); |
| 2371 | si->flags |= SWP_CONTINUED; |
| 2372 | } |
| 2373 | |
| 2374 | list_for_each_entry(list_page, &head->lru, lru) { |
| 2375 | unsigned char *map; |
| 2376 | |
| 2377 | /* |
| 2378 | * If the previous map said no continuation, but we've found |
| 2379 | * a continuation page, free our allocation and use this one. |
| 2380 | */ |
| 2381 | if (!(count & COUNT_CONTINUED)) |
| 2382 | goto out; |
| 2383 | |
| 2384 | map = kmap_atomic(list_page, KM_USER0) + offset; |
| 2385 | count = *map; |
| 2386 | kunmap_atomic(map, KM_USER0); |
| 2387 | |
| 2388 | /* |
| 2389 | * If this continuation count now has some space in it, |
| 2390 | * free our allocation and use this one. |
| 2391 | */ |
| 2392 | if ((count & ~COUNT_CONTINUED) != SWAP_CONT_MAX) |
| 2393 | goto out; |
| 2394 | } |
| 2395 | |
| 2396 | list_add_tail(&page->lru, &head->lru); |
| 2397 | page = NULL; /* now it's attached, don't free it */ |
| 2398 | out: |
| 2399 | spin_unlock(&swap_lock); |
| 2400 | outer: |
| 2401 | if (page) |
| 2402 | __free_page(page); |
| 2403 | return 0; |
| 2404 | } |
| 2405 | |
| 2406 | /* |
| 2407 | * swap_count_continued - when the original swap_map count is incremented |
| 2408 | * from SWAP_MAP_MAX, check if there is already a continuation page to carry |
| 2409 | * into, carry if so, or else fail until a new continuation page is allocated; |
| 2410 | * when the original swap_map count is decremented from 0 with continuation, |
| 2411 | * borrow from the continuation and report whether it still holds more. |
| 2412 | * Called while __swap_duplicate() or swap_entry_free() holds swap_lock. |
| 2413 | */ |
| 2414 | static bool swap_count_continued(struct swap_info_struct *si, |
| 2415 | pgoff_t offset, unsigned char count) |
| 2416 | { |
| 2417 | struct page *head; |
| 2418 | struct page *page; |
| 2419 | unsigned char *map; |
| 2420 | |
| 2421 | head = vmalloc_to_page(si->swap_map + offset); |
| 2422 | if (page_private(head) != SWP_CONTINUED) { |
| 2423 | BUG_ON(count & COUNT_CONTINUED); |
| 2424 | return false; /* need to add count continuation */ |
| 2425 | } |
| 2426 | |
| 2427 | offset &= ~PAGE_MASK; |
| 2428 | page = list_entry(head->lru.next, struct page, lru); |
| 2429 | map = kmap_atomic(page, KM_USER0) + offset; |
| 2430 | |
| 2431 | if (count == SWAP_MAP_MAX) /* initial increment from swap_map */ |
| 2432 | goto init_map; /* jump over SWAP_CONT_MAX checks */ |
| 2433 | |
| 2434 | if (count == (SWAP_MAP_MAX | COUNT_CONTINUED)) { /* incrementing */ |
| 2435 | /* |
| 2436 | * Think of how you add 1 to 999 |
| 2437 | */ |
| 2438 | while (*map == (SWAP_CONT_MAX | COUNT_CONTINUED)) { |
| 2439 | kunmap_atomic(map, KM_USER0); |
| 2440 | page = list_entry(page->lru.next, struct page, lru); |
| 2441 | BUG_ON(page == head); |
| 2442 | map = kmap_atomic(page, KM_USER0) + offset; |
| 2443 | } |
| 2444 | if (*map == SWAP_CONT_MAX) { |
| 2445 | kunmap_atomic(map, KM_USER0); |
| 2446 | page = list_entry(page->lru.next, struct page, lru); |
| 2447 | if (page == head) |
| 2448 | return false; /* add count continuation */ |
| 2449 | map = kmap_atomic(page, KM_USER0) + offset; |
| 2450 | init_map: *map = 0; /* we didn't zero the page */ |
| 2451 | } |
| 2452 | *map += 1; |
| 2453 | kunmap_atomic(map, KM_USER0); |
| 2454 | page = list_entry(page->lru.prev, struct page, lru); |
| 2455 | while (page != head) { |
| 2456 | map = kmap_atomic(page, KM_USER0) + offset; |
| 2457 | *map = COUNT_CONTINUED; |
| 2458 | kunmap_atomic(map, KM_USER0); |
| 2459 | page = list_entry(page->lru.prev, struct page, lru); |
| 2460 | } |
| 2461 | return true; /* incremented */ |
| 2462 | |
| 2463 | } else { /* decrementing */ |
| 2464 | /* |
| 2465 | * Think of how you subtract 1 from 1000 |
| 2466 | */ |
| 2467 | BUG_ON(count != COUNT_CONTINUED); |
| 2468 | while (*map == COUNT_CONTINUED) { |
| 2469 | kunmap_atomic(map, KM_USER0); |
| 2470 | page = list_entry(page->lru.next, struct page, lru); |
| 2471 | BUG_ON(page == head); |
| 2472 | map = kmap_atomic(page, KM_USER0) + offset; |
| 2473 | } |
| 2474 | BUG_ON(*map == 0); |
| 2475 | *map -= 1; |
| 2476 | if (*map == 0) |
| 2477 | count = 0; |
| 2478 | kunmap_atomic(map, KM_USER0); |
| 2479 | page = list_entry(page->lru.prev, struct page, lru); |
| 2480 | while (page != head) { |
| 2481 | map = kmap_atomic(page, KM_USER0) + offset; |
| 2482 | *map = SWAP_CONT_MAX | count; |
| 2483 | count = COUNT_CONTINUED; |
| 2484 | kunmap_atomic(map, KM_USER0); |
| 2485 | page = list_entry(page->lru.prev, struct page, lru); |
| 2486 | } |
| 2487 | return count == COUNT_CONTINUED; |
| 2488 | } |
| 2489 | } |
| 2490 | |
| 2491 | /* |
| 2492 | * free_swap_count_continuations - swapoff free all the continuation pages |
| 2493 | * appended to the swap_map, after swap_map is quiesced, before vfree'ing it. |
| 2494 | */ |
| 2495 | static void free_swap_count_continuations(struct swap_info_struct *si) |
| 2496 | { |
| 2497 | pgoff_t offset; |
| 2498 | |
| 2499 | for (offset = 0; offset < si->max; offset += PAGE_SIZE) { |
| 2500 | struct page *head; |
| 2501 | head = vmalloc_to_page(si->swap_map + offset); |
| 2502 | if (page_private(head)) { |
| 2503 | struct list_head *this, *next; |
| 2504 | list_for_each_safe(this, next, &head->lru) { |
| 2505 | struct page *page; |
| 2506 | page = list_entry(this, struct page, lru); |
| 2507 | list_del(this); |
| 2508 | __free_page(page); |
| 2509 | } |
| 2510 | } |
| 2511 | } |
| 2512 | } |