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1 | // SPDX-License-Identifier: GPL-2.0-only | |
2 | /* | |
3 | * linux/mm/swapfile.c | |
4 | * | |
5 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
6 | * Swap reorganised 29.12.95, Stephen Tweedie | |
7 | */ | |
8 | ||
9 | #include <linux/mm.h> | |
10 | #include <linux/sched/mm.h> | |
11 | #include <linux/sched/task.h> | |
12 | #include <linux/hugetlb.h> | |
13 | #include <linux/mman.h> | |
14 | #include <linux/slab.h> | |
15 | #include <linux/kernel_stat.h> | |
16 | #include <linux/swap.h> | |
17 | #include <linux/vmalloc.h> | |
18 | #include <linux/pagemap.h> | |
19 | #include <linux/namei.h> | |
20 | #include <linux/shmem_fs.h> | |
21 | #include <linux/blkdev.h> | |
22 | #include <linux/random.h> | |
23 | #include <linux/writeback.h> | |
24 | #include <linux/proc_fs.h> | |
25 | #include <linux/seq_file.h> | |
26 | #include <linux/init.h> | |
27 | #include <linux/ksm.h> | |
28 | #include <linux/rmap.h> | |
29 | #include <linux/security.h> | |
30 | #include <linux/backing-dev.h> | |
31 | #include <linux/mutex.h> | |
32 | #include <linux/capability.h> | |
33 | #include <linux/syscalls.h> | |
34 | #include <linux/memcontrol.h> | |
35 | #include <linux/poll.h> | |
36 | #include <linux/oom.h> | |
37 | #include <linux/frontswap.h> | |
38 | #include <linux/swapfile.h> | |
39 | #include <linux/export.h> | |
40 | #include <linux/swap_slots.h> | |
41 | #include <linux/sort.h> | |
42 | ||
43 | #include <asm/tlbflush.h> | |
44 | #include <linux/swapops.h> | |
45 | #include <linux/swap_cgroup.h> | |
46 | ||
47 | static bool swap_count_continued(struct swap_info_struct *, pgoff_t, | |
48 | unsigned char); | |
49 | static void free_swap_count_continuations(struct swap_info_struct *); | |
50 | static sector_t map_swap_entry(swp_entry_t, struct block_device**); | |
51 | ||
52 | DEFINE_SPINLOCK(swap_lock); | |
53 | static unsigned int nr_swapfiles; | |
54 | atomic_long_t nr_swap_pages; | |
55 | /* | |
56 | * Some modules use swappable objects and may try to swap them out under | |
57 | * memory pressure (via the shrinker). Before doing so, they may wish to | |
58 | * check to see if any swap space is available. | |
59 | */ | |
60 | EXPORT_SYMBOL_GPL(nr_swap_pages); | |
61 | /* protected with swap_lock. reading in vm_swap_full() doesn't need lock */ | |
62 | long total_swap_pages; | |
63 | static int least_priority = -1; | |
64 | ||
65 | static const char Bad_file[] = "Bad swap file entry "; | |
66 | static const char Unused_file[] = "Unused swap file entry "; | |
67 | static const char Bad_offset[] = "Bad swap offset entry "; | |
68 | static const char Unused_offset[] = "Unused swap offset entry "; | |
69 | ||
70 | /* | |
71 | * all active swap_info_structs | |
72 | * protected with swap_lock, and ordered by priority. | |
73 | */ | |
74 | PLIST_HEAD(swap_active_head); | |
75 | ||
76 | /* | |
77 | * all available (active, not full) swap_info_structs | |
78 | * protected with swap_avail_lock, ordered by priority. | |
79 | * This is used by get_swap_page() instead of swap_active_head | |
80 | * because swap_active_head includes all swap_info_structs, | |
81 | * but get_swap_page() doesn't need to look at full ones. | |
82 | * This uses its own lock instead of swap_lock because when a | |
83 | * swap_info_struct changes between not-full/full, it needs to | |
84 | * add/remove itself to/from this list, but the swap_info_struct->lock | |
85 | * is held and the locking order requires swap_lock to be taken | |
86 | * before any swap_info_struct->lock. | |
87 | */ | |
88 | static struct plist_head *swap_avail_heads; | |
89 | static DEFINE_SPINLOCK(swap_avail_lock); | |
90 | ||
91 | struct swap_info_struct *swap_info[MAX_SWAPFILES]; | |
92 | ||
93 | static DEFINE_MUTEX(swapon_mutex); | |
94 | ||
95 | static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait); | |
96 | /* Activity counter to indicate that a swapon or swapoff has occurred */ | |
97 | static atomic_t proc_poll_event = ATOMIC_INIT(0); | |
98 | ||
99 | atomic_t nr_rotate_swap = ATOMIC_INIT(0); | |
100 | ||
101 | static struct swap_info_struct *swap_type_to_swap_info(int type) | |
102 | { | |
103 | if (type >= READ_ONCE(nr_swapfiles)) | |
104 | return NULL; | |
105 | ||
106 | smp_rmb(); /* Pairs with smp_wmb in alloc_swap_info. */ | |
107 | return READ_ONCE(swap_info[type]); | |
108 | } | |
109 | ||
110 | static inline unsigned char swap_count(unsigned char ent) | |
111 | { | |
112 | return ent & ~SWAP_HAS_CACHE; /* may include COUNT_CONTINUED flag */ | |
113 | } | |
114 | ||
115 | /* Reclaim the swap entry anyway if possible */ | |
116 | #define TTRS_ANYWAY 0x1 | |
117 | /* | |
118 | * Reclaim the swap entry if there are no more mappings of the | |
119 | * corresponding page | |
120 | */ | |
121 | #define TTRS_UNMAPPED 0x2 | |
122 | /* Reclaim the swap entry if swap is getting full*/ | |
123 | #define TTRS_FULL 0x4 | |
124 | ||
125 | /* returns 1 if swap entry is freed */ | |
126 | static int __try_to_reclaim_swap(struct swap_info_struct *si, | |
127 | unsigned long offset, unsigned long flags) | |
128 | { | |
129 | swp_entry_t entry = swp_entry(si->type, offset); | |
130 | struct page *page; | |
131 | int ret = 0; | |
132 | ||
133 | page = find_get_page(swap_address_space(entry), offset); | |
134 | if (!page) | |
135 | return 0; | |
136 | /* | |
137 | * When this function is called from scan_swap_map_slots() and it's | |
138 | * called by vmscan.c at reclaiming pages. So, we hold a lock on a page, | |
139 | * here. We have to use trylock for avoiding deadlock. This is a special | |
140 | * case and you should use try_to_free_swap() with explicit lock_page() | |
141 | * in usual operations. | |
142 | */ | |
143 | if (trylock_page(page)) { | |
144 | if ((flags & TTRS_ANYWAY) || | |
145 | ((flags & TTRS_UNMAPPED) && !page_mapped(page)) || | |
146 | ((flags & TTRS_FULL) && mem_cgroup_swap_full(page))) | |
147 | ret = try_to_free_swap(page); | |
148 | unlock_page(page); | |
149 | } | |
150 | put_page(page); | |
151 | return ret; | |
152 | } | |
153 | ||
154 | static inline struct swap_extent *first_se(struct swap_info_struct *sis) | |
155 | { | |
156 | struct rb_node *rb = rb_first(&sis->swap_extent_root); | |
157 | return rb_entry(rb, struct swap_extent, rb_node); | |
158 | } | |
159 | ||
160 | static inline struct swap_extent *next_se(struct swap_extent *se) | |
161 | { | |
162 | struct rb_node *rb = rb_next(&se->rb_node); | |
163 | return rb ? rb_entry(rb, struct swap_extent, rb_node) : NULL; | |
164 | } | |
165 | ||
166 | /* | |
167 | * swapon tell device that all the old swap contents can be discarded, | |
168 | * to allow the swap device to optimize its wear-levelling. | |
169 | */ | |
170 | static int discard_swap(struct swap_info_struct *si) | |
171 | { | |
172 | struct swap_extent *se; | |
173 | sector_t start_block; | |
174 | sector_t nr_blocks; | |
175 | int err = 0; | |
176 | ||
177 | /* Do not discard the swap header page! */ | |
178 | se = first_se(si); | |
179 | start_block = (se->start_block + 1) << (PAGE_SHIFT - 9); | |
180 | nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9); | |
181 | if (nr_blocks) { | |
182 | err = blkdev_issue_discard(si->bdev, start_block, | |
183 | nr_blocks, GFP_KERNEL, 0); | |
184 | if (err) | |
185 | return err; | |
186 | cond_resched(); | |
187 | } | |
188 | ||
189 | for (se = next_se(se); se; se = next_se(se)) { | |
190 | start_block = se->start_block << (PAGE_SHIFT - 9); | |
191 | nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); | |
192 | ||
193 | err = blkdev_issue_discard(si->bdev, start_block, | |
194 | nr_blocks, GFP_KERNEL, 0); | |
195 | if (err) | |
196 | break; | |
197 | ||
198 | cond_resched(); | |
199 | } | |
200 | return err; /* That will often be -EOPNOTSUPP */ | |
201 | } | |
202 | ||
203 | static struct swap_extent * | |
204 | offset_to_swap_extent(struct swap_info_struct *sis, unsigned long offset) | |
205 | { | |
206 | struct swap_extent *se; | |
207 | struct rb_node *rb; | |
208 | ||
209 | rb = sis->swap_extent_root.rb_node; | |
210 | while (rb) { | |
211 | se = rb_entry(rb, struct swap_extent, rb_node); | |
212 | if (offset < se->start_page) | |
213 | rb = rb->rb_left; | |
214 | else if (offset >= se->start_page + se->nr_pages) | |
215 | rb = rb->rb_right; | |
216 | else | |
217 | return se; | |
218 | } | |
219 | /* It *must* be present */ | |
220 | BUG(); | |
221 | } | |
222 | ||
223 | /* | |
224 | * swap allocation tell device that a cluster of swap can now be discarded, | |
225 | * to allow the swap device to optimize its wear-levelling. | |
226 | */ | |
227 | static void discard_swap_cluster(struct swap_info_struct *si, | |
228 | pgoff_t start_page, pgoff_t nr_pages) | |
229 | { | |
230 | struct swap_extent *se = offset_to_swap_extent(si, start_page); | |
231 | ||
232 | while (nr_pages) { | |
233 | pgoff_t offset = start_page - se->start_page; | |
234 | sector_t start_block = se->start_block + offset; | |
235 | sector_t nr_blocks = se->nr_pages - offset; | |
236 | ||
237 | if (nr_blocks > nr_pages) | |
238 | nr_blocks = nr_pages; | |
239 | start_page += nr_blocks; | |
240 | nr_pages -= nr_blocks; | |
241 | ||
242 | start_block <<= PAGE_SHIFT - 9; | |
243 | nr_blocks <<= PAGE_SHIFT - 9; | |
244 | if (blkdev_issue_discard(si->bdev, start_block, | |
245 | nr_blocks, GFP_NOIO, 0)) | |
246 | break; | |
247 | ||
248 | se = next_se(se); | |
249 | } | |
250 | } | |
251 | ||
252 | #ifdef CONFIG_THP_SWAP | |
253 | #define SWAPFILE_CLUSTER HPAGE_PMD_NR | |
254 | ||
255 | #define swap_entry_size(size) (size) | |
256 | #else | |
257 | #define SWAPFILE_CLUSTER 256 | |
258 | ||
259 | /* | |
260 | * Define swap_entry_size() as constant to let compiler to optimize | |
261 | * out some code if !CONFIG_THP_SWAP | |
262 | */ | |
263 | #define swap_entry_size(size) 1 | |
264 | #endif | |
265 | #define LATENCY_LIMIT 256 | |
266 | ||
267 | static inline void cluster_set_flag(struct swap_cluster_info *info, | |
268 | unsigned int flag) | |
269 | { | |
270 | info->flags = flag; | |
271 | } | |
272 | ||
273 | static inline unsigned int cluster_count(struct swap_cluster_info *info) | |
274 | { | |
275 | return info->data; | |
276 | } | |
277 | ||
278 | static inline void cluster_set_count(struct swap_cluster_info *info, | |
279 | unsigned int c) | |
280 | { | |
281 | info->data = c; | |
282 | } | |
283 | ||
284 | static inline void cluster_set_count_flag(struct swap_cluster_info *info, | |
285 | unsigned int c, unsigned int f) | |
286 | { | |
287 | info->flags = f; | |
288 | info->data = c; | |
289 | } | |
290 | ||
291 | static inline unsigned int cluster_next(struct swap_cluster_info *info) | |
292 | { | |
293 | return info->data; | |
294 | } | |
295 | ||
296 | static inline void cluster_set_next(struct swap_cluster_info *info, | |
297 | unsigned int n) | |
298 | { | |
299 | info->data = n; | |
300 | } | |
301 | ||
302 | static inline void cluster_set_next_flag(struct swap_cluster_info *info, | |
303 | unsigned int n, unsigned int f) | |
304 | { | |
305 | info->flags = f; | |
306 | info->data = n; | |
307 | } | |
308 | ||
309 | static inline bool cluster_is_free(struct swap_cluster_info *info) | |
310 | { | |
311 | return info->flags & CLUSTER_FLAG_FREE; | |
312 | } | |
313 | ||
314 | static inline bool cluster_is_null(struct swap_cluster_info *info) | |
315 | { | |
316 | return info->flags & CLUSTER_FLAG_NEXT_NULL; | |
317 | } | |
318 | ||
319 | static inline void cluster_set_null(struct swap_cluster_info *info) | |
320 | { | |
321 | info->flags = CLUSTER_FLAG_NEXT_NULL; | |
322 | info->data = 0; | |
323 | } | |
324 | ||
325 | static inline bool cluster_is_huge(struct swap_cluster_info *info) | |
326 | { | |
327 | if (IS_ENABLED(CONFIG_THP_SWAP)) | |
328 | return info->flags & CLUSTER_FLAG_HUGE; | |
329 | return false; | |
330 | } | |
331 | ||
332 | static inline void cluster_clear_huge(struct swap_cluster_info *info) | |
333 | { | |
334 | info->flags &= ~CLUSTER_FLAG_HUGE; | |
335 | } | |
336 | ||
337 | static inline struct swap_cluster_info *lock_cluster(struct swap_info_struct *si, | |
338 | unsigned long offset) | |
339 | { | |
340 | struct swap_cluster_info *ci; | |
341 | ||
342 | ci = si->cluster_info; | |
343 | if (ci) { | |
344 | ci += offset / SWAPFILE_CLUSTER; | |
345 | spin_lock(&ci->lock); | |
346 | } | |
347 | return ci; | |
348 | } | |
349 | ||
350 | static inline void unlock_cluster(struct swap_cluster_info *ci) | |
351 | { | |
352 | if (ci) | |
353 | spin_unlock(&ci->lock); | |
354 | } | |
355 | ||
356 | /* | |
357 | * Determine the locking method in use for this device. Return | |
358 | * swap_cluster_info if SSD-style cluster-based locking is in place. | |
359 | */ | |
360 | static inline struct swap_cluster_info *lock_cluster_or_swap_info( | |
361 | struct swap_info_struct *si, unsigned long offset) | |
362 | { | |
363 | struct swap_cluster_info *ci; | |
364 | ||
365 | /* Try to use fine-grained SSD-style locking if available: */ | |
366 | ci = lock_cluster(si, offset); | |
367 | /* Otherwise, fall back to traditional, coarse locking: */ | |
368 | if (!ci) | |
369 | spin_lock(&si->lock); | |
370 | ||
371 | return ci; | |
372 | } | |
373 | ||
374 | static inline void unlock_cluster_or_swap_info(struct swap_info_struct *si, | |
375 | struct swap_cluster_info *ci) | |
376 | { | |
377 | if (ci) | |
378 | unlock_cluster(ci); | |
379 | else | |
380 | spin_unlock(&si->lock); | |
381 | } | |
382 | ||
383 | static inline bool cluster_list_empty(struct swap_cluster_list *list) | |
384 | { | |
385 | return cluster_is_null(&list->head); | |
386 | } | |
387 | ||
388 | static inline unsigned int cluster_list_first(struct swap_cluster_list *list) | |
389 | { | |
390 | return cluster_next(&list->head); | |
391 | } | |
392 | ||
393 | static void cluster_list_init(struct swap_cluster_list *list) | |
394 | { | |
395 | cluster_set_null(&list->head); | |
396 | cluster_set_null(&list->tail); | |
397 | } | |
398 | ||
399 | static void cluster_list_add_tail(struct swap_cluster_list *list, | |
400 | struct swap_cluster_info *ci, | |
401 | unsigned int idx) | |
402 | { | |
403 | if (cluster_list_empty(list)) { | |
404 | cluster_set_next_flag(&list->head, idx, 0); | |
405 | cluster_set_next_flag(&list->tail, idx, 0); | |
406 | } else { | |
407 | struct swap_cluster_info *ci_tail; | |
408 | unsigned int tail = cluster_next(&list->tail); | |
409 | ||
410 | /* | |
411 | * Nested cluster lock, but both cluster locks are | |
412 | * only acquired when we held swap_info_struct->lock | |
413 | */ | |
414 | ci_tail = ci + tail; | |
415 | spin_lock_nested(&ci_tail->lock, SINGLE_DEPTH_NESTING); | |
416 | cluster_set_next(ci_tail, idx); | |
417 | spin_unlock(&ci_tail->lock); | |
418 | cluster_set_next_flag(&list->tail, idx, 0); | |
419 | } | |
420 | } | |
421 | ||
422 | static unsigned int cluster_list_del_first(struct swap_cluster_list *list, | |
423 | struct swap_cluster_info *ci) | |
424 | { | |
425 | unsigned int idx; | |
426 | ||
427 | idx = cluster_next(&list->head); | |
428 | if (cluster_next(&list->tail) == idx) { | |
429 | cluster_set_null(&list->head); | |
430 | cluster_set_null(&list->tail); | |
431 | } else | |
432 | cluster_set_next_flag(&list->head, | |
433 | cluster_next(&ci[idx]), 0); | |
434 | ||
435 | return idx; | |
436 | } | |
437 | ||
438 | /* Add a cluster to discard list and schedule it to do discard */ | |
439 | static void swap_cluster_schedule_discard(struct swap_info_struct *si, | |
440 | unsigned int idx) | |
441 | { | |
442 | /* | |
443 | * If scan_swap_map() can't find a free cluster, it will check | |
444 | * si->swap_map directly. To make sure the discarding cluster isn't | |
445 | * taken by scan_swap_map(), mark the swap entries bad (occupied). It | |
446 | * will be cleared after discard | |
447 | */ | |
448 | memset(si->swap_map + idx * SWAPFILE_CLUSTER, | |
449 | SWAP_MAP_BAD, SWAPFILE_CLUSTER); | |
450 | ||
451 | cluster_list_add_tail(&si->discard_clusters, si->cluster_info, idx); | |
452 | ||
453 | schedule_work(&si->discard_work); | |
454 | } | |
455 | ||
456 | static void __free_cluster(struct swap_info_struct *si, unsigned long idx) | |
457 | { | |
458 | struct swap_cluster_info *ci = si->cluster_info; | |
459 | ||
460 | cluster_set_flag(ci + idx, CLUSTER_FLAG_FREE); | |
461 | cluster_list_add_tail(&si->free_clusters, ci, idx); | |
462 | } | |
463 | ||
464 | /* | |
465 | * Doing discard actually. After a cluster discard is finished, the cluster | |
466 | * will be added to free cluster list. caller should hold si->lock. | |
467 | */ | |
468 | static void swap_do_scheduled_discard(struct swap_info_struct *si) | |
469 | { | |
470 | struct swap_cluster_info *info, *ci; | |
471 | unsigned int idx; | |
472 | ||
473 | info = si->cluster_info; | |
474 | ||
475 | while (!cluster_list_empty(&si->discard_clusters)) { | |
476 | idx = cluster_list_del_first(&si->discard_clusters, info); | |
477 | spin_unlock(&si->lock); | |
478 | ||
479 | discard_swap_cluster(si, idx * SWAPFILE_CLUSTER, | |
480 | SWAPFILE_CLUSTER); | |
481 | ||
482 | spin_lock(&si->lock); | |
483 | ci = lock_cluster(si, idx * SWAPFILE_CLUSTER); | |
484 | __free_cluster(si, idx); | |
485 | memset(si->swap_map + idx * SWAPFILE_CLUSTER, | |
486 | 0, SWAPFILE_CLUSTER); | |
487 | unlock_cluster(ci); | |
488 | } | |
489 | } | |
490 | ||
491 | static void swap_discard_work(struct work_struct *work) | |
492 | { | |
493 | struct swap_info_struct *si; | |
494 | ||
495 | si = container_of(work, struct swap_info_struct, discard_work); | |
496 | ||
497 | spin_lock(&si->lock); | |
498 | swap_do_scheduled_discard(si); | |
499 | spin_unlock(&si->lock); | |
500 | } | |
501 | ||
502 | static void alloc_cluster(struct swap_info_struct *si, unsigned long idx) | |
503 | { | |
504 | struct swap_cluster_info *ci = si->cluster_info; | |
505 | ||
506 | VM_BUG_ON(cluster_list_first(&si->free_clusters) != idx); | |
507 | cluster_list_del_first(&si->free_clusters, ci); | |
508 | cluster_set_count_flag(ci + idx, 0, 0); | |
509 | } | |
510 | ||
511 | static void free_cluster(struct swap_info_struct *si, unsigned long idx) | |
512 | { | |
513 | struct swap_cluster_info *ci = si->cluster_info + idx; | |
514 | ||
515 | VM_BUG_ON(cluster_count(ci) != 0); | |
516 | /* | |
517 | * If the swap is discardable, prepare discard the cluster | |
518 | * instead of free it immediately. The cluster will be freed | |
519 | * after discard. | |
520 | */ | |
521 | if ((si->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) == | |
522 | (SWP_WRITEOK | SWP_PAGE_DISCARD)) { | |
523 | swap_cluster_schedule_discard(si, idx); | |
524 | return; | |
525 | } | |
526 | ||
527 | __free_cluster(si, idx); | |
528 | } | |
529 | ||
530 | /* | |
531 | * The cluster corresponding to page_nr will be used. The cluster will be | |
532 | * removed from free cluster list and its usage counter will be increased. | |
533 | */ | |
534 | static void inc_cluster_info_page(struct swap_info_struct *p, | |
535 | struct swap_cluster_info *cluster_info, unsigned long page_nr) | |
536 | { | |
537 | unsigned long idx = page_nr / SWAPFILE_CLUSTER; | |
538 | ||
539 | if (!cluster_info) | |
540 | return; | |
541 | if (cluster_is_free(&cluster_info[idx])) | |
542 | alloc_cluster(p, idx); | |
543 | ||
544 | VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER); | |
545 | cluster_set_count(&cluster_info[idx], | |
546 | cluster_count(&cluster_info[idx]) + 1); | |
547 | } | |
548 | ||
549 | /* | |
550 | * The cluster corresponding to page_nr decreases one usage. If the usage | |
551 | * counter becomes 0, which means no page in the cluster is in using, we can | |
552 | * optionally discard the cluster and add it to free cluster list. | |
553 | */ | |
554 | static void dec_cluster_info_page(struct swap_info_struct *p, | |
555 | struct swap_cluster_info *cluster_info, unsigned long page_nr) | |
556 | { | |
557 | unsigned long idx = page_nr / SWAPFILE_CLUSTER; | |
558 | ||
559 | if (!cluster_info) | |
560 | return; | |
561 | ||
562 | VM_BUG_ON(cluster_count(&cluster_info[idx]) == 0); | |
563 | cluster_set_count(&cluster_info[idx], | |
564 | cluster_count(&cluster_info[idx]) - 1); | |
565 | ||
566 | if (cluster_count(&cluster_info[idx]) == 0) | |
567 | free_cluster(p, idx); | |
568 | } | |
569 | ||
570 | /* | |
571 | * It's possible scan_swap_map() uses a free cluster in the middle of free | |
572 | * cluster list. Avoiding such abuse to avoid list corruption. | |
573 | */ | |
574 | static bool | |
575 | scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si, | |
576 | unsigned long offset) | |
577 | { | |
578 | struct percpu_cluster *percpu_cluster; | |
579 | bool conflict; | |
580 | ||
581 | offset /= SWAPFILE_CLUSTER; | |
582 | conflict = !cluster_list_empty(&si->free_clusters) && | |
583 | offset != cluster_list_first(&si->free_clusters) && | |
584 | cluster_is_free(&si->cluster_info[offset]); | |
585 | ||
586 | if (!conflict) | |
587 | return false; | |
588 | ||
589 | percpu_cluster = this_cpu_ptr(si->percpu_cluster); | |
590 | cluster_set_null(&percpu_cluster->index); | |
591 | return true; | |
592 | } | |
593 | ||
594 | /* | |
595 | * Try to get a swap entry from current cpu's swap entry pool (a cluster). This | |
596 | * might involve allocating a new cluster for current CPU too. | |
597 | */ | |
598 | static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si, | |
599 | unsigned long *offset, unsigned long *scan_base) | |
600 | { | |
601 | struct percpu_cluster *cluster; | |
602 | struct swap_cluster_info *ci; | |
603 | unsigned long tmp, max; | |
604 | ||
605 | new_cluster: | |
606 | cluster = this_cpu_ptr(si->percpu_cluster); | |
607 | if (cluster_is_null(&cluster->index)) { | |
608 | if (!cluster_list_empty(&si->free_clusters)) { | |
609 | cluster->index = si->free_clusters.head; | |
610 | cluster->next = cluster_next(&cluster->index) * | |
611 | SWAPFILE_CLUSTER; | |
612 | } else if (!cluster_list_empty(&si->discard_clusters)) { | |
613 | /* | |
614 | * we don't have free cluster but have some clusters in | |
615 | * discarding, do discard now and reclaim them, then | |
616 | * reread cluster_next_cpu since we dropped si->lock | |
617 | */ | |
618 | swap_do_scheduled_discard(si); | |
619 | *scan_base = this_cpu_read(*si->cluster_next_cpu); | |
620 | *offset = *scan_base; | |
621 | goto new_cluster; | |
622 | } else | |
623 | return false; | |
624 | } | |
625 | ||
626 | /* | |
627 | * Other CPUs can use our cluster if they can't find a free cluster, | |
628 | * check if there is still free entry in the cluster | |
629 | */ | |
630 | tmp = cluster->next; | |
631 | max = min_t(unsigned long, si->max, | |
632 | (cluster_next(&cluster->index) + 1) * SWAPFILE_CLUSTER); | |
633 | if (tmp < max) { | |
634 | ci = lock_cluster(si, tmp); | |
635 | while (tmp < max) { | |
636 | if (!si->swap_map[tmp]) | |
637 | break; | |
638 | tmp++; | |
639 | } | |
640 | unlock_cluster(ci); | |
641 | } | |
642 | if (tmp >= max) { | |
643 | cluster_set_null(&cluster->index); | |
644 | goto new_cluster; | |
645 | } | |
646 | cluster->next = tmp + 1; | |
647 | *offset = tmp; | |
648 | *scan_base = tmp; | |
649 | return true; | |
650 | } | |
651 | ||
652 | static void __del_from_avail_list(struct swap_info_struct *p) | |
653 | { | |
654 | int nid; | |
655 | ||
656 | for_each_node(nid) | |
657 | plist_del(&p->avail_lists[nid], &swap_avail_heads[nid]); | |
658 | } | |
659 | ||
660 | static void del_from_avail_list(struct swap_info_struct *p) | |
661 | { | |
662 | spin_lock(&swap_avail_lock); | |
663 | __del_from_avail_list(p); | |
664 | spin_unlock(&swap_avail_lock); | |
665 | } | |
666 | ||
667 | static void swap_range_alloc(struct swap_info_struct *si, unsigned long offset, | |
668 | unsigned int nr_entries) | |
669 | { | |
670 | unsigned int end = offset + nr_entries - 1; | |
671 | ||
672 | if (offset == si->lowest_bit) | |
673 | si->lowest_bit += nr_entries; | |
674 | if (end == si->highest_bit) | |
675 | si->highest_bit -= nr_entries; | |
676 | si->inuse_pages += nr_entries; | |
677 | if (si->inuse_pages == si->pages) { | |
678 | si->lowest_bit = si->max; | |
679 | si->highest_bit = 0; | |
680 | del_from_avail_list(si); | |
681 | } | |
682 | } | |
683 | ||
684 | static void add_to_avail_list(struct swap_info_struct *p) | |
685 | { | |
686 | int nid; | |
687 | ||
688 | spin_lock(&swap_avail_lock); | |
689 | for_each_node(nid) { | |
690 | WARN_ON(!plist_node_empty(&p->avail_lists[nid])); | |
691 | plist_add(&p->avail_lists[nid], &swap_avail_heads[nid]); | |
692 | } | |
693 | spin_unlock(&swap_avail_lock); | |
694 | } | |
695 | ||
696 | static void swap_range_free(struct swap_info_struct *si, unsigned long offset, | |
697 | unsigned int nr_entries) | |
698 | { | |
699 | unsigned long end = offset + nr_entries - 1; | |
700 | void (*swap_slot_free_notify)(struct block_device *, unsigned long); | |
701 | ||
702 | if (offset < si->lowest_bit) | |
703 | si->lowest_bit = offset; | |
704 | if (end > si->highest_bit) { | |
705 | bool was_full = !si->highest_bit; | |
706 | ||
707 | si->highest_bit = end; | |
708 | if (was_full && (si->flags & SWP_WRITEOK)) | |
709 | add_to_avail_list(si); | |
710 | } | |
711 | atomic_long_add(nr_entries, &nr_swap_pages); | |
712 | si->inuse_pages -= nr_entries; | |
713 | if (si->flags & SWP_BLKDEV) | |
714 | swap_slot_free_notify = | |
715 | si->bdev->bd_disk->fops->swap_slot_free_notify; | |
716 | else | |
717 | swap_slot_free_notify = NULL; | |
718 | while (offset <= end) { | |
719 | frontswap_invalidate_page(si->type, offset); | |
720 | if (swap_slot_free_notify) | |
721 | swap_slot_free_notify(si->bdev, offset); | |
722 | offset++; | |
723 | } | |
724 | } | |
725 | ||
726 | static void set_cluster_next(struct swap_info_struct *si, unsigned long next) | |
727 | { | |
728 | unsigned long prev; | |
729 | ||
730 | if (!(si->flags & SWP_SOLIDSTATE)) { | |
731 | si->cluster_next = next; | |
732 | return; | |
733 | } | |
734 | ||
735 | prev = this_cpu_read(*si->cluster_next_cpu); | |
736 | /* | |
737 | * Cross the swap address space size aligned trunk, choose | |
738 | * another trunk randomly to avoid lock contention on swap | |
739 | * address space if possible. | |
740 | */ | |
741 | if ((prev >> SWAP_ADDRESS_SPACE_SHIFT) != | |
742 | (next >> SWAP_ADDRESS_SPACE_SHIFT)) { | |
743 | /* No free swap slots available */ | |
744 | if (si->highest_bit <= si->lowest_bit) | |
745 | return; | |
746 | next = si->lowest_bit + | |
747 | prandom_u32_max(si->highest_bit - si->lowest_bit + 1); | |
748 | next = ALIGN_DOWN(next, SWAP_ADDRESS_SPACE_PAGES); | |
749 | next = max_t(unsigned int, next, si->lowest_bit); | |
750 | } | |
751 | this_cpu_write(*si->cluster_next_cpu, next); | |
752 | } | |
753 | ||
754 | static int scan_swap_map_slots(struct swap_info_struct *si, | |
755 | unsigned char usage, int nr, | |
756 | swp_entry_t slots[]) | |
757 | { | |
758 | struct swap_cluster_info *ci; | |
759 | unsigned long offset; | |
760 | unsigned long scan_base; | |
761 | unsigned long last_in_cluster = 0; | |
762 | int latency_ration = LATENCY_LIMIT; | |
763 | int n_ret = 0; | |
764 | bool scanned_many = false; | |
765 | ||
766 | /* | |
767 | * We try to cluster swap pages by allocating them sequentially | |
768 | * in swap. Once we've allocated SWAPFILE_CLUSTER pages this | |
769 | * way, however, we resort to first-free allocation, starting | |
770 | * a new cluster. This prevents us from scattering swap pages | |
771 | * all over the entire swap partition, so that we reduce | |
772 | * overall disk seek times between swap pages. -- sct | |
773 | * But we do now try to find an empty cluster. -Andrea | |
774 | * And we let swap pages go all over an SSD partition. Hugh | |
775 | */ | |
776 | ||
777 | si->flags += SWP_SCANNING; | |
778 | /* | |
779 | * Use percpu scan base for SSD to reduce lock contention on | |
780 | * cluster and swap cache. For HDD, sequential access is more | |
781 | * important. | |
782 | */ | |
783 | if (si->flags & SWP_SOLIDSTATE) | |
784 | scan_base = this_cpu_read(*si->cluster_next_cpu); | |
785 | else | |
786 | scan_base = si->cluster_next; | |
787 | offset = scan_base; | |
788 | ||
789 | /* SSD algorithm */ | |
790 | if (si->cluster_info) { | |
791 | if (!scan_swap_map_try_ssd_cluster(si, &offset, &scan_base)) | |
792 | goto scan; | |
793 | } else if (unlikely(!si->cluster_nr--)) { | |
794 | if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { | |
795 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
796 | goto checks; | |
797 | } | |
798 | ||
799 | spin_unlock(&si->lock); | |
800 | ||
801 | /* | |
802 | * If seek is expensive, start searching for new cluster from | |
803 | * start of partition, to minimize the span of allocated swap. | |
804 | * If seek is cheap, that is the SWP_SOLIDSTATE si->cluster_info | |
805 | * case, just handled by scan_swap_map_try_ssd_cluster() above. | |
806 | */ | |
807 | scan_base = offset = si->lowest_bit; | |
808 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; | |
809 | ||
810 | /* Locate the first empty (unaligned) cluster */ | |
811 | for (; last_in_cluster <= si->highest_bit; offset++) { | |
812 | if (si->swap_map[offset]) | |
813 | last_in_cluster = offset + SWAPFILE_CLUSTER; | |
814 | else if (offset == last_in_cluster) { | |
815 | spin_lock(&si->lock); | |
816 | offset -= SWAPFILE_CLUSTER - 1; | |
817 | si->cluster_next = offset; | |
818 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
819 | goto checks; | |
820 | } | |
821 | if (unlikely(--latency_ration < 0)) { | |
822 | cond_resched(); | |
823 | latency_ration = LATENCY_LIMIT; | |
824 | } | |
825 | } | |
826 | ||
827 | offset = scan_base; | |
828 | spin_lock(&si->lock); | |
829 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
830 | } | |
831 | ||
832 | checks: | |
833 | if (si->cluster_info) { | |
834 | while (scan_swap_map_ssd_cluster_conflict(si, offset)) { | |
835 | /* take a break if we already got some slots */ | |
836 | if (n_ret) | |
837 | goto done; | |
838 | if (!scan_swap_map_try_ssd_cluster(si, &offset, | |
839 | &scan_base)) | |
840 | goto scan; | |
841 | } | |
842 | } | |
843 | if (!(si->flags & SWP_WRITEOK)) | |
844 | goto no_page; | |
845 | if (!si->highest_bit) | |
846 | goto no_page; | |
847 | if (offset > si->highest_bit) | |
848 | scan_base = offset = si->lowest_bit; | |
849 | ||
850 | ci = lock_cluster(si, offset); | |
851 | /* reuse swap entry of cache-only swap if not busy. */ | |
852 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { | |
853 | int swap_was_freed; | |
854 | unlock_cluster(ci); | |
855 | spin_unlock(&si->lock); | |
856 | swap_was_freed = __try_to_reclaim_swap(si, offset, TTRS_ANYWAY); | |
857 | spin_lock(&si->lock); | |
858 | /* entry was freed successfully, try to use this again */ | |
859 | if (swap_was_freed) | |
860 | goto checks; | |
861 | goto scan; /* check next one */ | |
862 | } | |
863 | ||
864 | if (si->swap_map[offset]) { | |
865 | unlock_cluster(ci); | |
866 | if (!n_ret) | |
867 | goto scan; | |
868 | else | |
869 | goto done; | |
870 | } | |
871 | si->swap_map[offset] = usage; | |
872 | inc_cluster_info_page(si, si->cluster_info, offset); | |
873 | unlock_cluster(ci); | |
874 | ||
875 | swap_range_alloc(si, offset, 1); | |
876 | slots[n_ret++] = swp_entry(si->type, offset); | |
877 | ||
878 | /* got enough slots or reach max slots? */ | |
879 | if ((n_ret == nr) || (offset >= si->highest_bit)) | |
880 | goto done; | |
881 | ||
882 | /* search for next available slot */ | |
883 | ||
884 | /* time to take a break? */ | |
885 | if (unlikely(--latency_ration < 0)) { | |
886 | if (n_ret) | |
887 | goto done; | |
888 | spin_unlock(&si->lock); | |
889 | cond_resched(); | |
890 | spin_lock(&si->lock); | |
891 | latency_ration = LATENCY_LIMIT; | |
892 | } | |
893 | ||
894 | /* try to get more slots in cluster */ | |
895 | if (si->cluster_info) { | |
896 | if (scan_swap_map_try_ssd_cluster(si, &offset, &scan_base)) | |
897 | goto checks; | |
898 | } else if (si->cluster_nr && !si->swap_map[++offset]) { | |
899 | /* non-ssd case, still more slots in cluster? */ | |
900 | --si->cluster_nr; | |
901 | goto checks; | |
902 | } | |
903 | ||
904 | /* | |
905 | * Even if there's no free clusters available (fragmented), | |
906 | * try to scan a little more quickly with lock held unless we | |
907 | * have scanned too many slots already. | |
908 | */ | |
909 | if (!scanned_many) { | |
910 | unsigned long scan_limit; | |
911 | ||
912 | if (offset < scan_base) | |
913 | scan_limit = scan_base; | |
914 | else | |
915 | scan_limit = si->highest_bit; | |
916 | for (; offset <= scan_limit && --latency_ration > 0; | |
917 | offset++) { | |
918 | if (!si->swap_map[offset]) | |
919 | goto checks; | |
920 | } | |
921 | } | |
922 | ||
923 | done: | |
924 | set_cluster_next(si, offset + 1); | |
925 | si->flags -= SWP_SCANNING; | |
926 | return n_ret; | |
927 | ||
928 | scan: | |
929 | spin_unlock(&si->lock); | |
930 | while (++offset <= si->highest_bit) { | |
931 | if (!si->swap_map[offset]) { | |
932 | spin_lock(&si->lock); | |
933 | goto checks; | |
934 | } | |
935 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { | |
936 | spin_lock(&si->lock); | |
937 | goto checks; | |
938 | } | |
939 | if (unlikely(--latency_ration < 0)) { | |
940 | cond_resched(); | |
941 | latency_ration = LATENCY_LIMIT; | |
942 | scanned_many = true; | |
943 | } | |
944 | } | |
945 | offset = si->lowest_bit; | |
946 | while (offset < scan_base) { | |
947 | if (!si->swap_map[offset]) { | |
948 | spin_lock(&si->lock); | |
949 | goto checks; | |
950 | } | |
951 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { | |
952 | spin_lock(&si->lock); | |
953 | goto checks; | |
954 | } | |
955 | if (unlikely(--latency_ration < 0)) { | |
956 | cond_resched(); | |
957 | latency_ration = LATENCY_LIMIT; | |
958 | scanned_many = true; | |
959 | } | |
960 | offset++; | |
961 | } | |
962 | spin_lock(&si->lock); | |
963 | ||
964 | no_page: | |
965 | si->flags -= SWP_SCANNING; | |
966 | return n_ret; | |
967 | } | |
968 | ||
969 | static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) | |
970 | { | |
971 | unsigned long idx; | |
972 | struct swap_cluster_info *ci; | |
973 | unsigned long offset, i; | |
974 | unsigned char *map; | |
975 | ||
976 | /* | |
977 | * Should not even be attempting cluster allocations when huge | |
978 | * page swap is disabled. Warn and fail the allocation. | |
979 | */ | |
980 | if (!IS_ENABLED(CONFIG_THP_SWAP)) { | |
981 | VM_WARN_ON_ONCE(1); | |
982 | return 0; | |
983 | } | |
984 | ||
985 | if (cluster_list_empty(&si->free_clusters)) | |
986 | return 0; | |
987 | ||
988 | idx = cluster_list_first(&si->free_clusters); | |
989 | offset = idx * SWAPFILE_CLUSTER; | |
990 | ci = lock_cluster(si, offset); | |
991 | alloc_cluster(si, idx); | |
992 | cluster_set_count_flag(ci, SWAPFILE_CLUSTER, CLUSTER_FLAG_HUGE); | |
993 | ||
994 | map = si->swap_map + offset; | |
995 | for (i = 0; i < SWAPFILE_CLUSTER; i++) | |
996 | map[i] = SWAP_HAS_CACHE; | |
997 | unlock_cluster(ci); | |
998 | swap_range_alloc(si, offset, SWAPFILE_CLUSTER); | |
999 | *slot = swp_entry(si->type, offset); | |
1000 | ||
1001 | return 1; | |
1002 | } | |
1003 | ||
1004 | static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx) | |
1005 | { | |
1006 | unsigned long offset = idx * SWAPFILE_CLUSTER; | |
1007 | struct swap_cluster_info *ci; | |
1008 | ||
1009 | ci = lock_cluster(si, offset); | |
1010 | memset(si->swap_map + offset, 0, SWAPFILE_CLUSTER); | |
1011 | cluster_set_count_flag(ci, 0, 0); | |
1012 | free_cluster(si, idx); | |
1013 | unlock_cluster(ci); | |
1014 | swap_range_free(si, offset, SWAPFILE_CLUSTER); | |
1015 | } | |
1016 | ||
1017 | static unsigned long scan_swap_map(struct swap_info_struct *si, | |
1018 | unsigned char usage) | |
1019 | { | |
1020 | swp_entry_t entry; | |
1021 | int n_ret; | |
1022 | ||
1023 | n_ret = scan_swap_map_slots(si, usage, 1, &entry); | |
1024 | ||
1025 | if (n_ret) | |
1026 | return swp_offset(entry); | |
1027 | else | |
1028 | return 0; | |
1029 | ||
1030 | } | |
1031 | ||
1032 | int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size) | |
1033 | { | |
1034 | unsigned long size = swap_entry_size(entry_size); | |
1035 | struct swap_info_struct *si, *next; | |
1036 | long avail_pgs; | |
1037 | int n_ret = 0; | |
1038 | int node; | |
1039 | ||
1040 | /* Only single cluster request supported */ | |
1041 | WARN_ON_ONCE(n_goal > 1 && size == SWAPFILE_CLUSTER); | |
1042 | ||
1043 | avail_pgs = atomic_long_read(&nr_swap_pages) / size; | |
1044 | if (avail_pgs <= 0) | |
1045 | goto noswap; | |
1046 | ||
1047 | n_goal = min3((long)n_goal, (long)SWAP_BATCH, avail_pgs); | |
1048 | ||
1049 | atomic_long_sub(n_goal * size, &nr_swap_pages); | |
1050 | ||
1051 | spin_lock(&swap_avail_lock); | |
1052 | ||
1053 | start_over: | |
1054 | node = numa_node_id(); | |
1055 | plist_for_each_entry_safe(si, next, &swap_avail_heads[node], avail_lists[node]) { | |
1056 | /* requeue si to after same-priority siblings */ | |
1057 | plist_requeue(&si->avail_lists[node], &swap_avail_heads[node]); | |
1058 | spin_unlock(&swap_avail_lock); | |
1059 | spin_lock(&si->lock); | |
1060 | if (!si->highest_bit || !(si->flags & SWP_WRITEOK)) { | |
1061 | spin_lock(&swap_avail_lock); | |
1062 | if (plist_node_empty(&si->avail_lists[node])) { | |
1063 | spin_unlock(&si->lock); | |
1064 | goto nextsi; | |
1065 | } | |
1066 | WARN(!si->highest_bit, | |
1067 | "swap_info %d in list but !highest_bit\n", | |
1068 | si->type); | |
1069 | WARN(!(si->flags & SWP_WRITEOK), | |
1070 | "swap_info %d in list but !SWP_WRITEOK\n", | |
1071 | si->type); | |
1072 | __del_from_avail_list(si); | |
1073 | spin_unlock(&si->lock); | |
1074 | goto nextsi; | |
1075 | } | |
1076 | if (size == SWAPFILE_CLUSTER) { | |
1077 | if (!(si->flags & SWP_FS)) | |
1078 | n_ret = swap_alloc_cluster(si, swp_entries); | |
1079 | } else | |
1080 | n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, | |
1081 | n_goal, swp_entries); | |
1082 | spin_unlock(&si->lock); | |
1083 | if (n_ret || size == SWAPFILE_CLUSTER) | |
1084 | goto check_out; | |
1085 | pr_debug("scan_swap_map of si %d failed to find offset\n", | |
1086 | si->type); | |
1087 | ||
1088 | spin_lock(&swap_avail_lock); | |
1089 | nextsi: | |
1090 | /* | |
1091 | * if we got here, it's likely that si was almost full before, | |
1092 | * and since scan_swap_map() can drop the si->lock, multiple | |
1093 | * callers probably all tried to get a page from the same si | |
1094 | * and it filled up before we could get one; or, the si filled | |
1095 | * up between us dropping swap_avail_lock and taking si->lock. | |
1096 | * Since we dropped the swap_avail_lock, the swap_avail_head | |
1097 | * list may have been modified; so if next is still in the | |
1098 | * swap_avail_head list then try it, otherwise start over | |
1099 | * if we have not gotten any slots. | |
1100 | */ | |
1101 | if (plist_node_empty(&next->avail_lists[node])) | |
1102 | goto start_over; | |
1103 | } | |
1104 | ||
1105 | spin_unlock(&swap_avail_lock); | |
1106 | ||
1107 | check_out: | |
1108 | if (n_ret < n_goal) | |
1109 | atomic_long_add((long)(n_goal - n_ret) * size, | |
1110 | &nr_swap_pages); | |
1111 | noswap: | |
1112 | return n_ret; | |
1113 | } | |
1114 | ||
1115 | /* The only caller of this function is now suspend routine */ | |
1116 | swp_entry_t get_swap_page_of_type(int type) | |
1117 | { | |
1118 | struct swap_info_struct *si = swap_type_to_swap_info(type); | |
1119 | pgoff_t offset; | |
1120 | ||
1121 | if (!si) | |
1122 | goto fail; | |
1123 | ||
1124 | spin_lock(&si->lock); | |
1125 | if (si->flags & SWP_WRITEOK) { | |
1126 | atomic_long_dec(&nr_swap_pages); | |
1127 | /* This is called for allocating swap entry, not cache */ | |
1128 | offset = scan_swap_map(si, 1); | |
1129 | if (offset) { | |
1130 | spin_unlock(&si->lock); | |
1131 | return swp_entry(type, offset); | |
1132 | } | |
1133 | atomic_long_inc(&nr_swap_pages); | |
1134 | } | |
1135 | spin_unlock(&si->lock); | |
1136 | fail: | |
1137 | return (swp_entry_t) {0}; | |
1138 | } | |
1139 | ||
1140 | static struct swap_info_struct *__swap_info_get(swp_entry_t entry) | |
1141 | { | |
1142 | struct swap_info_struct *p; | |
1143 | unsigned long offset; | |
1144 | ||
1145 | if (!entry.val) | |
1146 | goto out; | |
1147 | p = swp_swap_info(entry); | |
1148 | if (!p) | |
1149 | goto bad_nofile; | |
1150 | if (!(p->flags & SWP_USED)) | |
1151 | goto bad_device; | |
1152 | offset = swp_offset(entry); | |
1153 | if (offset >= p->max) | |
1154 | goto bad_offset; | |
1155 | return p; | |
1156 | ||
1157 | bad_offset: | |
1158 | pr_err("swap_info_get: %s%08lx\n", Bad_offset, entry.val); | |
1159 | goto out; | |
1160 | bad_device: | |
1161 | pr_err("swap_info_get: %s%08lx\n", Unused_file, entry.val); | |
1162 | goto out; | |
1163 | bad_nofile: | |
1164 | pr_err("swap_info_get: %s%08lx\n", Bad_file, entry.val); | |
1165 | out: | |
1166 | return NULL; | |
1167 | } | |
1168 | ||
1169 | static struct swap_info_struct *_swap_info_get(swp_entry_t entry) | |
1170 | { | |
1171 | struct swap_info_struct *p; | |
1172 | ||
1173 | p = __swap_info_get(entry); | |
1174 | if (!p) | |
1175 | goto out; | |
1176 | if (!p->swap_map[swp_offset(entry)]) | |
1177 | goto bad_free; | |
1178 | return p; | |
1179 | ||
1180 | bad_free: | |
1181 | pr_err("swap_info_get: %s%08lx\n", Unused_offset, entry.val); | |
1182 | goto out; | |
1183 | out: | |
1184 | return NULL; | |
1185 | } | |
1186 | ||
1187 | static struct swap_info_struct *swap_info_get(swp_entry_t entry) | |
1188 | { | |
1189 | struct swap_info_struct *p; | |
1190 | ||
1191 | p = _swap_info_get(entry); | |
1192 | if (p) | |
1193 | spin_lock(&p->lock); | |
1194 | return p; | |
1195 | } | |
1196 | ||
1197 | static struct swap_info_struct *swap_info_get_cont(swp_entry_t entry, | |
1198 | struct swap_info_struct *q) | |
1199 | { | |
1200 | struct swap_info_struct *p; | |
1201 | ||
1202 | p = _swap_info_get(entry); | |
1203 | ||
1204 | if (p != q) { | |
1205 | if (q != NULL) | |
1206 | spin_unlock(&q->lock); | |
1207 | if (p != NULL) | |
1208 | spin_lock(&p->lock); | |
1209 | } | |
1210 | return p; | |
1211 | } | |
1212 | ||
1213 | static unsigned char __swap_entry_free_locked(struct swap_info_struct *p, | |
1214 | unsigned long offset, | |
1215 | unsigned char usage) | |
1216 | { | |
1217 | unsigned char count; | |
1218 | unsigned char has_cache; | |
1219 | ||
1220 | count = p->swap_map[offset]; | |
1221 | ||
1222 | has_cache = count & SWAP_HAS_CACHE; | |
1223 | count &= ~SWAP_HAS_CACHE; | |
1224 | ||
1225 | if (usage == SWAP_HAS_CACHE) { | |
1226 | VM_BUG_ON(!has_cache); | |
1227 | has_cache = 0; | |
1228 | } else if (count == SWAP_MAP_SHMEM) { | |
1229 | /* | |
1230 | * Or we could insist on shmem.c using a special | |
1231 | * swap_shmem_free() and free_shmem_swap_and_cache()... | |
1232 | */ | |
1233 | count = 0; | |
1234 | } else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) { | |
1235 | if (count == COUNT_CONTINUED) { | |
1236 | if (swap_count_continued(p, offset, count)) | |
1237 | count = SWAP_MAP_MAX | COUNT_CONTINUED; | |
1238 | else | |
1239 | count = SWAP_MAP_MAX; | |
1240 | } else | |
1241 | count--; | |
1242 | } | |
1243 | ||
1244 | usage = count | has_cache; | |
1245 | p->swap_map[offset] = usage ? : SWAP_HAS_CACHE; | |
1246 | ||
1247 | return usage; | |
1248 | } | |
1249 | ||
1250 | /* | |
1251 | * Check whether swap entry is valid in the swap device. If so, | |
1252 | * return pointer to swap_info_struct, and keep the swap entry valid | |
1253 | * via preventing the swap device from being swapoff, until | |
1254 | * put_swap_device() is called. Otherwise return NULL. | |
1255 | * | |
1256 | * The entirety of the RCU read critical section must come before the | |
1257 | * return from or after the call to synchronize_rcu() in | |
1258 | * enable_swap_info() or swapoff(). So if "si->flags & SWP_VALID" is | |
1259 | * true, the si->map, si->cluster_info, etc. must be valid in the | |
1260 | * critical section. | |
1261 | * | |
1262 | * Notice that swapoff or swapoff+swapon can still happen before the | |
1263 | * rcu_read_lock() in get_swap_device() or after the rcu_read_unlock() | |
1264 | * in put_swap_device() if there isn't any other way to prevent | |
1265 | * swapoff, such as page lock, page table lock, etc. The caller must | |
1266 | * be prepared for that. For example, the following situation is | |
1267 | * possible. | |
1268 | * | |
1269 | * CPU1 CPU2 | |
1270 | * do_swap_page() | |
1271 | * ... swapoff+swapon | |
1272 | * __read_swap_cache_async() | |
1273 | * swapcache_prepare() | |
1274 | * __swap_duplicate() | |
1275 | * // check swap_map | |
1276 | * // verify PTE not changed | |
1277 | * | |
1278 | * In __swap_duplicate(), the swap_map need to be checked before | |
1279 | * changing partly because the specified swap entry may be for another | |
1280 | * swap device which has been swapoff. And in do_swap_page(), after | |
1281 | * the page is read from the swap device, the PTE is verified not | |
1282 | * changed with the page table locked to check whether the swap device | |
1283 | * has been swapoff or swapoff+swapon. | |
1284 | */ | |
1285 | struct swap_info_struct *get_swap_device(swp_entry_t entry) | |
1286 | { | |
1287 | struct swap_info_struct *si; | |
1288 | unsigned long offset; | |
1289 | ||
1290 | if (!entry.val) | |
1291 | goto out; | |
1292 | si = swp_swap_info(entry); | |
1293 | if (!si) | |
1294 | goto bad_nofile; | |
1295 | ||
1296 | rcu_read_lock(); | |
1297 | if (!(si->flags & SWP_VALID)) | |
1298 | goto unlock_out; | |
1299 | offset = swp_offset(entry); | |
1300 | if (offset >= si->max) | |
1301 | goto unlock_out; | |
1302 | ||
1303 | return si; | |
1304 | bad_nofile: | |
1305 | pr_err("%s: %s%08lx\n", __func__, Bad_file, entry.val); | |
1306 | out: | |
1307 | return NULL; | |
1308 | unlock_out: | |
1309 | rcu_read_unlock(); | |
1310 | return NULL; | |
1311 | } | |
1312 | ||
1313 | static unsigned char __swap_entry_free(struct swap_info_struct *p, | |
1314 | swp_entry_t entry) | |
1315 | { | |
1316 | struct swap_cluster_info *ci; | |
1317 | unsigned long offset = swp_offset(entry); | |
1318 | unsigned char usage; | |
1319 | ||
1320 | ci = lock_cluster_or_swap_info(p, offset); | |
1321 | usage = __swap_entry_free_locked(p, offset, 1); | |
1322 | unlock_cluster_or_swap_info(p, ci); | |
1323 | if (!usage) | |
1324 | free_swap_slot(entry); | |
1325 | ||
1326 | return usage; | |
1327 | } | |
1328 | ||
1329 | static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry) | |
1330 | { | |
1331 | struct swap_cluster_info *ci; | |
1332 | unsigned long offset = swp_offset(entry); | |
1333 | unsigned char count; | |
1334 | ||
1335 | ci = lock_cluster(p, offset); | |
1336 | count = p->swap_map[offset]; | |
1337 | VM_BUG_ON(count != SWAP_HAS_CACHE); | |
1338 | p->swap_map[offset] = 0; | |
1339 | dec_cluster_info_page(p, p->cluster_info, offset); | |
1340 | unlock_cluster(ci); | |
1341 | ||
1342 | mem_cgroup_uncharge_swap(entry, 1); | |
1343 | swap_range_free(p, offset, 1); | |
1344 | } | |
1345 | ||
1346 | /* | |
1347 | * Caller has made sure that the swap device corresponding to entry | |
1348 | * is still around or has not been recycled. | |
1349 | */ | |
1350 | void swap_free(swp_entry_t entry) | |
1351 | { | |
1352 | struct swap_info_struct *p; | |
1353 | ||
1354 | p = _swap_info_get(entry); | |
1355 | if (p) | |
1356 | __swap_entry_free(p, entry); | |
1357 | } | |
1358 | ||
1359 | /* | |
1360 | * Called after dropping swapcache to decrease refcnt to swap entries. | |
1361 | */ | |
1362 | void put_swap_page(struct page *page, swp_entry_t entry) | |
1363 | { | |
1364 | unsigned long offset = swp_offset(entry); | |
1365 | unsigned long idx = offset / SWAPFILE_CLUSTER; | |
1366 | struct swap_cluster_info *ci; | |
1367 | struct swap_info_struct *si; | |
1368 | unsigned char *map; | |
1369 | unsigned int i, free_entries = 0; | |
1370 | unsigned char val; | |
1371 | int size = swap_entry_size(hpage_nr_pages(page)); | |
1372 | ||
1373 | si = _swap_info_get(entry); | |
1374 | if (!si) | |
1375 | return; | |
1376 | ||
1377 | ci = lock_cluster_or_swap_info(si, offset); | |
1378 | if (size == SWAPFILE_CLUSTER) { | |
1379 | VM_BUG_ON(!cluster_is_huge(ci)); | |
1380 | map = si->swap_map + offset; | |
1381 | for (i = 0; i < SWAPFILE_CLUSTER; i++) { | |
1382 | val = map[i]; | |
1383 | VM_BUG_ON(!(val & SWAP_HAS_CACHE)); | |
1384 | if (val == SWAP_HAS_CACHE) | |
1385 | free_entries++; | |
1386 | } | |
1387 | cluster_clear_huge(ci); | |
1388 | if (free_entries == SWAPFILE_CLUSTER) { | |
1389 | unlock_cluster_or_swap_info(si, ci); | |
1390 | spin_lock(&si->lock); | |
1391 | mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER); | |
1392 | swap_free_cluster(si, idx); | |
1393 | spin_unlock(&si->lock); | |
1394 | return; | |
1395 | } | |
1396 | } | |
1397 | for (i = 0; i < size; i++, entry.val++) { | |
1398 | if (!__swap_entry_free_locked(si, offset + i, SWAP_HAS_CACHE)) { | |
1399 | unlock_cluster_or_swap_info(si, ci); | |
1400 | free_swap_slot(entry); | |
1401 | if (i == size - 1) | |
1402 | return; | |
1403 | lock_cluster_or_swap_info(si, offset); | |
1404 | } | |
1405 | } | |
1406 | unlock_cluster_or_swap_info(si, ci); | |
1407 | } | |
1408 | ||
1409 | #ifdef CONFIG_THP_SWAP | |
1410 | int split_swap_cluster(swp_entry_t entry) | |
1411 | { | |
1412 | struct swap_info_struct *si; | |
1413 | struct swap_cluster_info *ci; | |
1414 | unsigned long offset = swp_offset(entry); | |
1415 | ||
1416 | si = _swap_info_get(entry); | |
1417 | if (!si) | |
1418 | return -EBUSY; | |
1419 | ci = lock_cluster(si, offset); | |
1420 | cluster_clear_huge(ci); | |
1421 | unlock_cluster(ci); | |
1422 | return 0; | |
1423 | } | |
1424 | #endif | |
1425 | ||
1426 | static int swp_entry_cmp(const void *ent1, const void *ent2) | |
1427 | { | |
1428 | const swp_entry_t *e1 = ent1, *e2 = ent2; | |
1429 | ||
1430 | return (int)swp_type(*e1) - (int)swp_type(*e2); | |
1431 | } | |
1432 | ||
1433 | void swapcache_free_entries(swp_entry_t *entries, int n) | |
1434 | { | |
1435 | struct swap_info_struct *p, *prev; | |
1436 | int i; | |
1437 | ||
1438 | if (n <= 0) | |
1439 | return; | |
1440 | ||
1441 | prev = NULL; | |
1442 | p = NULL; | |
1443 | ||
1444 | /* | |
1445 | * Sort swap entries by swap device, so each lock is only taken once. | |
1446 | * nr_swapfiles isn't absolutely correct, but the overhead of sort() is | |
1447 | * so low that it isn't necessary to optimize further. | |
1448 | */ | |
1449 | if (nr_swapfiles > 1) | |
1450 | sort(entries, n, sizeof(entries[0]), swp_entry_cmp, NULL); | |
1451 | for (i = 0; i < n; ++i) { | |
1452 | p = swap_info_get_cont(entries[i], prev); | |
1453 | if (p) | |
1454 | swap_entry_free(p, entries[i]); | |
1455 | prev = p; | |
1456 | } | |
1457 | if (p) | |
1458 | spin_unlock(&p->lock); | |
1459 | } | |
1460 | ||
1461 | /* | |
1462 | * How many references to page are currently swapped out? | |
1463 | * This does not give an exact answer when swap count is continued, | |
1464 | * but does include the high COUNT_CONTINUED flag to allow for that. | |
1465 | */ | |
1466 | int page_swapcount(struct page *page) | |
1467 | { | |
1468 | int count = 0; | |
1469 | struct swap_info_struct *p; | |
1470 | struct swap_cluster_info *ci; | |
1471 | swp_entry_t entry; | |
1472 | unsigned long offset; | |
1473 | ||
1474 | entry.val = page_private(page); | |
1475 | p = _swap_info_get(entry); | |
1476 | if (p) { | |
1477 | offset = swp_offset(entry); | |
1478 | ci = lock_cluster_or_swap_info(p, offset); | |
1479 | count = swap_count(p->swap_map[offset]); | |
1480 | unlock_cluster_or_swap_info(p, ci); | |
1481 | } | |
1482 | return count; | |
1483 | } | |
1484 | ||
1485 | int __swap_count(swp_entry_t entry) | |
1486 | { | |
1487 | struct swap_info_struct *si; | |
1488 | pgoff_t offset = swp_offset(entry); | |
1489 | int count = 0; | |
1490 | ||
1491 | si = get_swap_device(entry); | |
1492 | if (si) { | |
1493 | count = swap_count(si->swap_map[offset]); | |
1494 | put_swap_device(si); | |
1495 | } | |
1496 | return count; | |
1497 | } | |
1498 | ||
1499 | static int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry) | |
1500 | { | |
1501 | int count = 0; | |
1502 | pgoff_t offset = swp_offset(entry); | |
1503 | struct swap_cluster_info *ci; | |
1504 | ||
1505 | ci = lock_cluster_or_swap_info(si, offset); | |
1506 | count = swap_count(si->swap_map[offset]); | |
1507 | unlock_cluster_or_swap_info(si, ci); | |
1508 | return count; | |
1509 | } | |
1510 | ||
1511 | /* | |
1512 | * How many references to @entry are currently swapped out? | |
1513 | * This does not give an exact answer when swap count is continued, | |
1514 | * but does include the high COUNT_CONTINUED flag to allow for that. | |
1515 | */ | |
1516 | int __swp_swapcount(swp_entry_t entry) | |
1517 | { | |
1518 | int count = 0; | |
1519 | struct swap_info_struct *si; | |
1520 | ||
1521 | si = get_swap_device(entry); | |
1522 | if (si) { | |
1523 | count = swap_swapcount(si, entry); | |
1524 | put_swap_device(si); | |
1525 | } | |
1526 | return count; | |
1527 | } | |
1528 | ||
1529 | /* | |
1530 | * How many references to @entry are currently swapped out? | |
1531 | * This considers COUNT_CONTINUED so it returns exact answer. | |
1532 | */ | |
1533 | int swp_swapcount(swp_entry_t entry) | |
1534 | { | |
1535 | int count, tmp_count, n; | |
1536 | struct swap_info_struct *p; | |
1537 | struct swap_cluster_info *ci; | |
1538 | struct page *page; | |
1539 | pgoff_t offset; | |
1540 | unsigned char *map; | |
1541 | ||
1542 | p = _swap_info_get(entry); | |
1543 | if (!p) | |
1544 | return 0; | |
1545 | ||
1546 | offset = swp_offset(entry); | |
1547 | ||
1548 | ci = lock_cluster_or_swap_info(p, offset); | |
1549 | ||
1550 | count = swap_count(p->swap_map[offset]); | |
1551 | if (!(count & COUNT_CONTINUED)) | |
1552 | goto out; | |
1553 | ||
1554 | count &= ~COUNT_CONTINUED; | |
1555 | n = SWAP_MAP_MAX + 1; | |
1556 | ||
1557 | page = vmalloc_to_page(p->swap_map + offset); | |
1558 | offset &= ~PAGE_MASK; | |
1559 | VM_BUG_ON(page_private(page) != SWP_CONTINUED); | |
1560 | ||
1561 | do { | |
1562 | page = list_next_entry(page, lru); | |
1563 | map = kmap_atomic(page); | |
1564 | tmp_count = map[offset]; | |
1565 | kunmap_atomic(map); | |
1566 | ||
1567 | count += (tmp_count & ~COUNT_CONTINUED) * n; | |
1568 | n *= (SWAP_CONT_MAX + 1); | |
1569 | } while (tmp_count & COUNT_CONTINUED); | |
1570 | out: | |
1571 | unlock_cluster_or_swap_info(p, ci); | |
1572 | return count; | |
1573 | } | |
1574 | ||
1575 | static bool swap_page_trans_huge_swapped(struct swap_info_struct *si, | |
1576 | swp_entry_t entry) | |
1577 | { | |
1578 | struct swap_cluster_info *ci; | |
1579 | unsigned char *map = si->swap_map; | |
1580 | unsigned long roffset = swp_offset(entry); | |
1581 | unsigned long offset = round_down(roffset, SWAPFILE_CLUSTER); | |
1582 | int i; | |
1583 | bool ret = false; | |
1584 | ||
1585 | ci = lock_cluster_or_swap_info(si, offset); | |
1586 | if (!ci || !cluster_is_huge(ci)) { | |
1587 | if (swap_count(map[roffset])) | |
1588 | ret = true; | |
1589 | goto unlock_out; | |
1590 | } | |
1591 | for (i = 0; i < SWAPFILE_CLUSTER; i++) { | |
1592 | if (swap_count(map[offset + i])) { | |
1593 | ret = true; | |
1594 | break; | |
1595 | } | |
1596 | } | |
1597 | unlock_out: | |
1598 | unlock_cluster_or_swap_info(si, ci); | |
1599 | return ret; | |
1600 | } | |
1601 | ||
1602 | static bool page_swapped(struct page *page) | |
1603 | { | |
1604 | swp_entry_t entry; | |
1605 | struct swap_info_struct *si; | |
1606 | ||
1607 | if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!PageTransCompound(page))) | |
1608 | return page_swapcount(page) != 0; | |
1609 | ||
1610 | page = compound_head(page); | |
1611 | entry.val = page_private(page); | |
1612 | si = _swap_info_get(entry); | |
1613 | if (si) | |
1614 | return swap_page_trans_huge_swapped(si, entry); | |
1615 | return false; | |
1616 | } | |
1617 | ||
1618 | static int page_trans_huge_map_swapcount(struct page *page, int *total_mapcount, | |
1619 | int *total_swapcount) | |
1620 | { | |
1621 | int i, map_swapcount, _total_mapcount, _total_swapcount; | |
1622 | unsigned long offset = 0; | |
1623 | struct swap_info_struct *si; | |
1624 | struct swap_cluster_info *ci = NULL; | |
1625 | unsigned char *map = NULL; | |
1626 | int mapcount, swapcount = 0; | |
1627 | ||
1628 | /* hugetlbfs shouldn't call it */ | |
1629 | VM_BUG_ON_PAGE(PageHuge(page), page); | |
1630 | ||
1631 | if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!PageTransCompound(page))) { | |
1632 | mapcount = page_trans_huge_mapcount(page, total_mapcount); | |
1633 | if (PageSwapCache(page)) | |
1634 | swapcount = page_swapcount(page); | |
1635 | if (total_swapcount) | |
1636 | *total_swapcount = swapcount; | |
1637 | return mapcount + swapcount; | |
1638 | } | |
1639 | ||
1640 | page = compound_head(page); | |
1641 | ||
1642 | _total_mapcount = _total_swapcount = map_swapcount = 0; | |
1643 | if (PageSwapCache(page)) { | |
1644 | swp_entry_t entry; | |
1645 | ||
1646 | entry.val = page_private(page); | |
1647 | si = _swap_info_get(entry); | |
1648 | if (si) { | |
1649 | map = si->swap_map; | |
1650 | offset = swp_offset(entry); | |
1651 | } | |
1652 | } | |
1653 | if (map) | |
1654 | ci = lock_cluster(si, offset); | |
1655 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1656 | mapcount = atomic_read(&page[i]._mapcount) + 1; | |
1657 | _total_mapcount += mapcount; | |
1658 | if (map) { | |
1659 | swapcount = swap_count(map[offset + i]); | |
1660 | _total_swapcount += swapcount; | |
1661 | } | |
1662 | map_swapcount = max(map_swapcount, mapcount + swapcount); | |
1663 | } | |
1664 | unlock_cluster(ci); | |
1665 | if (PageDoubleMap(page)) { | |
1666 | map_swapcount -= 1; | |
1667 | _total_mapcount -= HPAGE_PMD_NR; | |
1668 | } | |
1669 | mapcount = compound_mapcount(page); | |
1670 | map_swapcount += mapcount; | |
1671 | _total_mapcount += mapcount; | |
1672 | if (total_mapcount) | |
1673 | *total_mapcount = _total_mapcount; | |
1674 | if (total_swapcount) | |
1675 | *total_swapcount = _total_swapcount; | |
1676 | ||
1677 | return map_swapcount; | |
1678 | } | |
1679 | ||
1680 | /* | |
1681 | * We can write to an anon page without COW if there are no other references | |
1682 | * to it. And as a side-effect, free up its swap: because the old content | |
1683 | * on disk will never be read, and seeking back there to write new content | |
1684 | * later would only waste time away from clustering. | |
1685 | * | |
1686 | * NOTE: total_map_swapcount should not be relied upon by the caller if | |
1687 | * reuse_swap_page() returns false, but it may be always overwritten | |
1688 | * (see the other implementation for CONFIG_SWAP=n). | |
1689 | */ | |
1690 | bool reuse_swap_page(struct page *page, int *total_map_swapcount) | |
1691 | { | |
1692 | int count, total_mapcount, total_swapcount; | |
1693 | ||
1694 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
1695 | if (unlikely(PageKsm(page))) | |
1696 | return false; | |
1697 | count = page_trans_huge_map_swapcount(page, &total_mapcount, | |
1698 | &total_swapcount); | |
1699 | if (total_map_swapcount) | |
1700 | *total_map_swapcount = total_mapcount + total_swapcount; | |
1701 | if (count == 1 && PageSwapCache(page) && | |
1702 | (likely(!PageTransCompound(page)) || | |
1703 | /* The remaining swap count will be freed soon */ | |
1704 | total_swapcount == page_swapcount(page))) { | |
1705 | if (!PageWriteback(page)) { | |
1706 | page = compound_head(page); | |
1707 | delete_from_swap_cache(page); | |
1708 | SetPageDirty(page); | |
1709 | } else { | |
1710 | swp_entry_t entry; | |
1711 | struct swap_info_struct *p; | |
1712 | ||
1713 | entry.val = page_private(page); | |
1714 | p = swap_info_get(entry); | |
1715 | if (p->flags & SWP_STABLE_WRITES) { | |
1716 | spin_unlock(&p->lock); | |
1717 | return false; | |
1718 | } | |
1719 | spin_unlock(&p->lock); | |
1720 | } | |
1721 | } | |
1722 | ||
1723 | return count <= 1; | |
1724 | } | |
1725 | ||
1726 | /* | |
1727 | * If swap is getting full, or if there are no more mappings of this page, | |
1728 | * then try_to_free_swap is called to free its swap space. | |
1729 | */ | |
1730 | int try_to_free_swap(struct page *page) | |
1731 | { | |
1732 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
1733 | ||
1734 | if (!PageSwapCache(page)) | |
1735 | return 0; | |
1736 | if (PageWriteback(page)) | |
1737 | return 0; | |
1738 | if (page_swapped(page)) | |
1739 | return 0; | |
1740 | ||
1741 | /* | |
1742 | * Once hibernation has begun to create its image of memory, | |
1743 | * there's a danger that one of the calls to try_to_free_swap() | |
1744 | * - most probably a call from __try_to_reclaim_swap() while | |
1745 | * hibernation is allocating its own swap pages for the image, | |
1746 | * but conceivably even a call from memory reclaim - will free | |
1747 | * the swap from a page which has already been recorded in the | |
1748 | * image as a clean swapcache page, and then reuse its swap for | |
1749 | * another page of the image. On waking from hibernation, the | |
1750 | * original page might be freed under memory pressure, then | |
1751 | * later read back in from swap, now with the wrong data. | |
1752 | * | |
1753 | * Hibernation suspends storage while it is writing the image | |
1754 | * to disk so check that here. | |
1755 | */ | |
1756 | if (pm_suspended_storage()) | |
1757 | return 0; | |
1758 | ||
1759 | page = compound_head(page); | |
1760 | delete_from_swap_cache(page); | |
1761 | SetPageDirty(page); | |
1762 | return 1; | |
1763 | } | |
1764 | ||
1765 | /* | |
1766 | * Free the swap entry like above, but also try to | |
1767 | * free the page cache entry if it is the last user. | |
1768 | */ | |
1769 | int free_swap_and_cache(swp_entry_t entry) | |
1770 | { | |
1771 | struct swap_info_struct *p; | |
1772 | unsigned char count; | |
1773 | ||
1774 | if (non_swap_entry(entry)) | |
1775 | return 1; | |
1776 | ||
1777 | p = _swap_info_get(entry); | |
1778 | if (p) { | |
1779 | count = __swap_entry_free(p, entry); | |
1780 | if (count == SWAP_HAS_CACHE && | |
1781 | !swap_page_trans_huge_swapped(p, entry)) | |
1782 | __try_to_reclaim_swap(p, swp_offset(entry), | |
1783 | TTRS_UNMAPPED | TTRS_FULL); | |
1784 | } | |
1785 | return p != NULL; | |
1786 | } | |
1787 | ||
1788 | #ifdef CONFIG_HIBERNATION | |
1789 | /* | |
1790 | * Find the swap type that corresponds to given device (if any). | |
1791 | * | |
1792 | * @offset - number of the PAGE_SIZE-sized block of the device, starting | |
1793 | * from 0, in which the swap header is expected to be located. | |
1794 | * | |
1795 | * This is needed for the suspend to disk (aka swsusp). | |
1796 | */ | |
1797 | int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) | |
1798 | { | |
1799 | struct block_device *bdev = NULL; | |
1800 | int type; | |
1801 | ||
1802 | if (device) | |
1803 | bdev = bdget(device); | |
1804 | ||
1805 | spin_lock(&swap_lock); | |
1806 | for (type = 0; type < nr_swapfiles; type++) { | |
1807 | struct swap_info_struct *sis = swap_info[type]; | |
1808 | ||
1809 | if (!(sis->flags & SWP_WRITEOK)) | |
1810 | continue; | |
1811 | ||
1812 | if (!bdev) { | |
1813 | if (bdev_p) | |
1814 | *bdev_p = bdgrab(sis->bdev); | |
1815 | ||
1816 | spin_unlock(&swap_lock); | |
1817 | return type; | |
1818 | } | |
1819 | if (bdev == sis->bdev) { | |
1820 | struct swap_extent *se = first_se(sis); | |
1821 | ||
1822 | if (se->start_block == offset) { | |
1823 | if (bdev_p) | |
1824 | *bdev_p = bdgrab(sis->bdev); | |
1825 | ||
1826 | spin_unlock(&swap_lock); | |
1827 | bdput(bdev); | |
1828 | return type; | |
1829 | } | |
1830 | } | |
1831 | } | |
1832 | spin_unlock(&swap_lock); | |
1833 | if (bdev) | |
1834 | bdput(bdev); | |
1835 | ||
1836 | return -ENODEV; | |
1837 | } | |
1838 | ||
1839 | /* | |
1840 | * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev | |
1841 | * corresponding to given index in swap_info (swap type). | |
1842 | */ | |
1843 | sector_t swapdev_block(int type, pgoff_t offset) | |
1844 | { | |
1845 | struct block_device *bdev; | |
1846 | struct swap_info_struct *si = swap_type_to_swap_info(type); | |
1847 | ||
1848 | if (!si || !(si->flags & SWP_WRITEOK)) | |
1849 | return 0; | |
1850 | return map_swap_entry(swp_entry(type, offset), &bdev); | |
1851 | } | |
1852 | ||
1853 | /* | |
1854 | * Return either the total number of swap pages of given type, or the number | |
1855 | * of free pages of that type (depending on @free) | |
1856 | * | |
1857 | * This is needed for software suspend | |
1858 | */ | |
1859 | unsigned int count_swap_pages(int type, int free) | |
1860 | { | |
1861 | unsigned int n = 0; | |
1862 | ||
1863 | spin_lock(&swap_lock); | |
1864 | if ((unsigned int)type < nr_swapfiles) { | |
1865 | struct swap_info_struct *sis = swap_info[type]; | |
1866 | ||
1867 | spin_lock(&sis->lock); | |
1868 | if (sis->flags & SWP_WRITEOK) { | |
1869 | n = sis->pages; | |
1870 | if (free) | |
1871 | n -= sis->inuse_pages; | |
1872 | } | |
1873 | spin_unlock(&sis->lock); | |
1874 | } | |
1875 | spin_unlock(&swap_lock); | |
1876 | return n; | |
1877 | } | |
1878 | #endif /* CONFIG_HIBERNATION */ | |
1879 | ||
1880 | static inline int pte_same_as_swp(pte_t pte, pte_t swp_pte) | |
1881 | { | |
1882 | return pte_same(pte_swp_clear_soft_dirty(pte), swp_pte); | |
1883 | } | |
1884 | ||
1885 | /* | |
1886 | * No need to decide whether this PTE shares the swap entry with others, | |
1887 | * just let do_wp_page work it out if a write is requested later - to | |
1888 | * force COW, vm_page_prot omits write permission from any private vma. | |
1889 | */ | |
1890 | static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, | |
1891 | unsigned long addr, swp_entry_t entry, struct page *page) | |
1892 | { | |
1893 | struct page *swapcache; | |
1894 | spinlock_t *ptl; | |
1895 | pte_t *pte; | |
1896 | int ret = 1; | |
1897 | ||
1898 | swapcache = page; | |
1899 | page = ksm_might_need_to_copy(page, vma, addr); | |
1900 | if (unlikely(!page)) | |
1901 | return -ENOMEM; | |
1902 | ||
1903 | pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); | |
1904 | if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) { | |
1905 | ret = 0; | |
1906 | goto out; | |
1907 | } | |
1908 | ||
1909 | dec_mm_counter(vma->vm_mm, MM_SWAPENTS); | |
1910 | inc_mm_counter(vma->vm_mm, MM_ANONPAGES); | |
1911 | get_page(page); | |
1912 | set_pte_at(vma->vm_mm, addr, pte, | |
1913 | pte_mkold(mk_pte(page, vma->vm_page_prot))); | |
1914 | if (page == swapcache) { | |
1915 | page_add_anon_rmap(page, vma, addr, false); | |
1916 | } else { /* ksm created a completely new copy */ | |
1917 | page_add_new_anon_rmap(page, vma, addr, false); | |
1918 | lru_cache_add_active_or_unevictable(page, vma); | |
1919 | } | |
1920 | swap_free(entry); | |
1921 | /* | |
1922 | * Move the page to the active list so it is not | |
1923 | * immediately swapped out again after swapon. | |
1924 | */ | |
1925 | activate_page(page); | |
1926 | out: | |
1927 | pte_unmap_unlock(pte, ptl); | |
1928 | if (page != swapcache) { | |
1929 | unlock_page(page); | |
1930 | put_page(page); | |
1931 | } | |
1932 | return ret; | |
1933 | } | |
1934 | ||
1935 | static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, | |
1936 | unsigned long addr, unsigned long end, | |
1937 | unsigned int type, bool frontswap, | |
1938 | unsigned long *fs_pages_to_unuse) | |
1939 | { | |
1940 | struct page *page; | |
1941 | swp_entry_t entry; | |
1942 | pte_t *pte; | |
1943 | struct swap_info_struct *si; | |
1944 | unsigned long offset; | |
1945 | int ret = 0; | |
1946 | volatile unsigned char *swap_map; | |
1947 | ||
1948 | si = swap_info[type]; | |
1949 | pte = pte_offset_map(pmd, addr); | |
1950 | do { | |
1951 | struct vm_fault vmf; | |
1952 | ||
1953 | if (!is_swap_pte(*pte)) | |
1954 | continue; | |
1955 | ||
1956 | entry = pte_to_swp_entry(*pte); | |
1957 | if (swp_type(entry) != type) | |
1958 | continue; | |
1959 | ||
1960 | offset = swp_offset(entry); | |
1961 | if (frontswap && !frontswap_test(si, offset)) | |
1962 | continue; | |
1963 | ||
1964 | pte_unmap(pte); | |
1965 | swap_map = &si->swap_map[offset]; | |
1966 | page = lookup_swap_cache(entry, vma, addr); | |
1967 | if (!page) { | |
1968 | vmf.vma = vma; | |
1969 | vmf.address = addr; | |
1970 | vmf.pmd = pmd; | |
1971 | page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, | |
1972 | &vmf); | |
1973 | } | |
1974 | if (!page) { | |
1975 | if (*swap_map == 0 || *swap_map == SWAP_MAP_BAD) | |
1976 | goto try_next; | |
1977 | return -ENOMEM; | |
1978 | } | |
1979 | ||
1980 | lock_page(page); | |
1981 | wait_on_page_writeback(page); | |
1982 | ret = unuse_pte(vma, pmd, addr, entry, page); | |
1983 | if (ret < 0) { | |
1984 | unlock_page(page); | |
1985 | put_page(page); | |
1986 | goto out; | |
1987 | } | |
1988 | ||
1989 | try_to_free_swap(page); | |
1990 | unlock_page(page); | |
1991 | put_page(page); | |
1992 | ||
1993 | if (*fs_pages_to_unuse && !--(*fs_pages_to_unuse)) { | |
1994 | ret = FRONTSWAP_PAGES_UNUSED; | |
1995 | goto out; | |
1996 | } | |
1997 | try_next: | |
1998 | pte = pte_offset_map(pmd, addr); | |
1999 | } while (pte++, addr += PAGE_SIZE, addr != end); | |
2000 | pte_unmap(pte - 1); | |
2001 | ||
2002 | ret = 0; | |
2003 | out: | |
2004 | return ret; | |
2005 | } | |
2006 | ||
2007 | static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, | |
2008 | unsigned long addr, unsigned long end, | |
2009 | unsigned int type, bool frontswap, | |
2010 | unsigned long *fs_pages_to_unuse) | |
2011 | { | |
2012 | pmd_t *pmd; | |
2013 | unsigned long next; | |
2014 | int ret; | |
2015 | ||
2016 | pmd = pmd_offset(pud, addr); | |
2017 | do { | |
2018 | cond_resched(); | |
2019 | next = pmd_addr_end(addr, end); | |
2020 | if (pmd_none_or_trans_huge_or_clear_bad(pmd)) | |
2021 | continue; | |
2022 | ret = unuse_pte_range(vma, pmd, addr, next, type, | |
2023 | frontswap, fs_pages_to_unuse); | |
2024 | if (ret) | |
2025 | return ret; | |
2026 | } while (pmd++, addr = next, addr != end); | |
2027 | return 0; | |
2028 | } | |
2029 | ||
2030 | static inline int unuse_pud_range(struct vm_area_struct *vma, p4d_t *p4d, | |
2031 | unsigned long addr, unsigned long end, | |
2032 | unsigned int type, bool frontswap, | |
2033 | unsigned long *fs_pages_to_unuse) | |
2034 | { | |
2035 | pud_t *pud; | |
2036 | unsigned long next; | |
2037 | int ret; | |
2038 | ||
2039 | pud = pud_offset(p4d, addr); | |
2040 | do { | |
2041 | next = pud_addr_end(addr, end); | |
2042 | if (pud_none_or_clear_bad(pud)) | |
2043 | continue; | |
2044 | ret = unuse_pmd_range(vma, pud, addr, next, type, | |
2045 | frontswap, fs_pages_to_unuse); | |
2046 | if (ret) | |
2047 | return ret; | |
2048 | } while (pud++, addr = next, addr != end); | |
2049 | return 0; | |
2050 | } | |
2051 | ||
2052 | static inline int unuse_p4d_range(struct vm_area_struct *vma, pgd_t *pgd, | |
2053 | unsigned long addr, unsigned long end, | |
2054 | unsigned int type, bool frontswap, | |
2055 | unsigned long *fs_pages_to_unuse) | |
2056 | { | |
2057 | p4d_t *p4d; | |
2058 | unsigned long next; | |
2059 | int ret; | |
2060 | ||
2061 | p4d = p4d_offset(pgd, addr); | |
2062 | do { | |
2063 | next = p4d_addr_end(addr, end); | |
2064 | if (p4d_none_or_clear_bad(p4d)) | |
2065 | continue; | |
2066 | ret = unuse_pud_range(vma, p4d, addr, next, type, | |
2067 | frontswap, fs_pages_to_unuse); | |
2068 | if (ret) | |
2069 | return ret; | |
2070 | } while (p4d++, addr = next, addr != end); | |
2071 | return 0; | |
2072 | } | |
2073 | ||
2074 | static int unuse_vma(struct vm_area_struct *vma, unsigned int type, | |
2075 | bool frontswap, unsigned long *fs_pages_to_unuse) | |
2076 | { | |
2077 | pgd_t *pgd; | |
2078 | unsigned long addr, end, next; | |
2079 | int ret; | |
2080 | ||
2081 | addr = vma->vm_start; | |
2082 | end = vma->vm_end; | |
2083 | ||
2084 | pgd = pgd_offset(vma->vm_mm, addr); | |
2085 | do { | |
2086 | next = pgd_addr_end(addr, end); | |
2087 | if (pgd_none_or_clear_bad(pgd)) | |
2088 | continue; | |
2089 | ret = unuse_p4d_range(vma, pgd, addr, next, type, | |
2090 | frontswap, fs_pages_to_unuse); | |
2091 | if (ret) | |
2092 | return ret; | |
2093 | } while (pgd++, addr = next, addr != end); | |
2094 | return 0; | |
2095 | } | |
2096 | ||
2097 | static int unuse_mm(struct mm_struct *mm, unsigned int type, | |
2098 | bool frontswap, unsigned long *fs_pages_to_unuse) | |
2099 | { | |
2100 | struct vm_area_struct *vma; | |
2101 | int ret = 0; | |
2102 | ||
2103 | mmap_read_lock(mm); | |
2104 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
2105 | if (vma->anon_vma) { | |
2106 | ret = unuse_vma(vma, type, frontswap, | |
2107 | fs_pages_to_unuse); | |
2108 | if (ret) | |
2109 | break; | |
2110 | } | |
2111 | cond_resched(); | |
2112 | } | |
2113 | mmap_read_unlock(mm); | |
2114 | return ret; | |
2115 | } | |
2116 | ||
2117 | /* | |
2118 | * Scan swap_map (or frontswap_map if frontswap parameter is true) | |
2119 | * from current position to next entry still in use. Return 0 | |
2120 | * if there are no inuse entries after prev till end of the map. | |
2121 | */ | |
2122 | static unsigned int find_next_to_unuse(struct swap_info_struct *si, | |
2123 | unsigned int prev, bool frontswap) | |
2124 | { | |
2125 | unsigned int i; | |
2126 | unsigned char count; | |
2127 | ||
2128 | /* | |
2129 | * No need for swap_lock here: we're just looking | |
2130 | * for whether an entry is in use, not modifying it; false | |
2131 | * hits are okay, and sys_swapoff() has already prevented new | |
2132 | * allocations from this area (while holding swap_lock). | |
2133 | */ | |
2134 | for (i = prev + 1; i < si->max; i++) { | |
2135 | count = READ_ONCE(si->swap_map[i]); | |
2136 | if (count && swap_count(count) != SWAP_MAP_BAD) | |
2137 | if (!frontswap || frontswap_test(si, i)) | |
2138 | break; | |
2139 | if ((i % LATENCY_LIMIT) == 0) | |
2140 | cond_resched(); | |
2141 | } | |
2142 | ||
2143 | if (i == si->max) | |
2144 | i = 0; | |
2145 | ||
2146 | return i; | |
2147 | } | |
2148 | ||
2149 | /* | |
2150 | * If the boolean frontswap is true, only unuse pages_to_unuse pages; | |
2151 | * pages_to_unuse==0 means all pages; ignored if frontswap is false | |
2152 | */ | |
2153 | int try_to_unuse(unsigned int type, bool frontswap, | |
2154 | unsigned long pages_to_unuse) | |
2155 | { | |
2156 | struct mm_struct *prev_mm; | |
2157 | struct mm_struct *mm; | |
2158 | struct list_head *p; | |
2159 | int retval = 0; | |
2160 | struct swap_info_struct *si = swap_info[type]; | |
2161 | struct page *page; | |
2162 | swp_entry_t entry; | |
2163 | unsigned int i; | |
2164 | ||
2165 | if (!READ_ONCE(si->inuse_pages)) | |
2166 | return 0; | |
2167 | ||
2168 | if (!frontswap) | |
2169 | pages_to_unuse = 0; | |
2170 | ||
2171 | retry: | |
2172 | retval = shmem_unuse(type, frontswap, &pages_to_unuse); | |
2173 | if (retval) | |
2174 | goto out; | |
2175 | ||
2176 | prev_mm = &init_mm; | |
2177 | mmget(prev_mm); | |
2178 | ||
2179 | spin_lock(&mmlist_lock); | |
2180 | p = &init_mm.mmlist; | |
2181 | while (READ_ONCE(si->inuse_pages) && | |
2182 | !signal_pending(current) && | |
2183 | (p = p->next) != &init_mm.mmlist) { | |
2184 | ||
2185 | mm = list_entry(p, struct mm_struct, mmlist); | |
2186 | if (!mmget_not_zero(mm)) | |
2187 | continue; | |
2188 | spin_unlock(&mmlist_lock); | |
2189 | mmput(prev_mm); | |
2190 | prev_mm = mm; | |
2191 | retval = unuse_mm(mm, type, frontswap, &pages_to_unuse); | |
2192 | ||
2193 | if (retval) { | |
2194 | mmput(prev_mm); | |
2195 | goto out; | |
2196 | } | |
2197 | ||
2198 | /* | |
2199 | * Make sure that we aren't completely killing | |
2200 | * interactive performance. | |
2201 | */ | |
2202 | cond_resched(); | |
2203 | spin_lock(&mmlist_lock); | |
2204 | } | |
2205 | spin_unlock(&mmlist_lock); | |
2206 | ||
2207 | mmput(prev_mm); | |
2208 | ||
2209 | i = 0; | |
2210 | while (READ_ONCE(si->inuse_pages) && | |
2211 | !signal_pending(current) && | |
2212 | (i = find_next_to_unuse(si, i, frontswap)) != 0) { | |
2213 | ||
2214 | entry = swp_entry(type, i); | |
2215 | page = find_get_page(swap_address_space(entry), i); | |
2216 | if (!page) | |
2217 | continue; | |
2218 | ||
2219 | /* | |
2220 | * It is conceivable that a racing task removed this page from | |
2221 | * swap cache just before we acquired the page lock. The page | |
2222 | * might even be back in swap cache on another swap area. But | |
2223 | * that is okay, try_to_free_swap() only removes stale pages. | |
2224 | */ | |
2225 | lock_page(page); | |
2226 | wait_on_page_writeback(page); | |
2227 | try_to_free_swap(page); | |
2228 | unlock_page(page); | |
2229 | put_page(page); | |
2230 | ||
2231 | /* | |
2232 | * For frontswap, we just need to unuse pages_to_unuse, if | |
2233 | * it was specified. Need not check frontswap again here as | |
2234 | * we already zeroed out pages_to_unuse if not frontswap. | |
2235 | */ | |
2236 | if (pages_to_unuse && --pages_to_unuse == 0) | |
2237 | goto out; | |
2238 | } | |
2239 | ||
2240 | /* | |
2241 | * Lets check again to see if there are still swap entries in the map. | |
2242 | * If yes, we would need to do retry the unuse logic again. | |
2243 | * Under global memory pressure, swap entries can be reinserted back | |
2244 | * into process space after the mmlist loop above passes over them. | |
2245 | * | |
2246 | * Limit the number of retries? No: when mmget_not_zero() above fails, | |
2247 | * that mm is likely to be freeing swap from exit_mmap(), which proceeds | |
2248 | * at its own independent pace; and even shmem_writepage() could have | |
2249 | * been preempted after get_swap_page(), temporarily hiding that swap. | |
2250 | * It's easy and robust (though cpu-intensive) just to keep retrying. | |
2251 | */ | |
2252 | if (READ_ONCE(si->inuse_pages)) { | |
2253 | if (!signal_pending(current)) | |
2254 | goto retry; | |
2255 | retval = -EINTR; | |
2256 | } | |
2257 | out: | |
2258 | return (retval == FRONTSWAP_PAGES_UNUSED) ? 0 : retval; | |
2259 | } | |
2260 | ||
2261 | /* | |
2262 | * After a successful try_to_unuse, if no swap is now in use, we know | |
2263 | * we can empty the mmlist. swap_lock must be held on entry and exit. | |
2264 | * Note that mmlist_lock nests inside swap_lock, and an mm must be | |
2265 | * added to the mmlist just after page_duplicate - before would be racy. | |
2266 | */ | |
2267 | static void drain_mmlist(void) | |
2268 | { | |
2269 | struct list_head *p, *next; | |
2270 | unsigned int type; | |
2271 | ||
2272 | for (type = 0; type < nr_swapfiles; type++) | |
2273 | if (swap_info[type]->inuse_pages) | |
2274 | return; | |
2275 | spin_lock(&mmlist_lock); | |
2276 | list_for_each_safe(p, next, &init_mm.mmlist) | |
2277 | list_del_init(p); | |
2278 | spin_unlock(&mmlist_lock); | |
2279 | } | |
2280 | ||
2281 | /* | |
2282 | * Use this swapdev's extent info to locate the (PAGE_SIZE) block which | |
2283 | * corresponds to page offset for the specified swap entry. | |
2284 | * Note that the type of this function is sector_t, but it returns page offset | |
2285 | * into the bdev, not sector offset. | |
2286 | */ | |
2287 | static sector_t map_swap_entry(swp_entry_t entry, struct block_device **bdev) | |
2288 | { | |
2289 | struct swap_info_struct *sis; | |
2290 | struct swap_extent *se; | |
2291 | pgoff_t offset; | |
2292 | ||
2293 | sis = swp_swap_info(entry); | |
2294 | *bdev = sis->bdev; | |
2295 | ||
2296 | offset = swp_offset(entry); | |
2297 | se = offset_to_swap_extent(sis, offset); | |
2298 | return se->start_block + (offset - se->start_page); | |
2299 | } | |
2300 | ||
2301 | /* | |
2302 | * Returns the page offset into bdev for the specified page's swap entry. | |
2303 | */ | |
2304 | sector_t map_swap_page(struct page *page, struct block_device **bdev) | |
2305 | { | |
2306 | swp_entry_t entry; | |
2307 | entry.val = page_private(page); | |
2308 | return map_swap_entry(entry, bdev); | |
2309 | } | |
2310 | ||
2311 | /* | |
2312 | * Free all of a swapdev's extent information | |
2313 | */ | |
2314 | static void destroy_swap_extents(struct swap_info_struct *sis) | |
2315 | { | |
2316 | while (!RB_EMPTY_ROOT(&sis->swap_extent_root)) { | |
2317 | struct rb_node *rb = sis->swap_extent_root.rb_node; | |
2318 | struct swap_extent *se = rb_entry(rb, struct swap_extent, rb_node); | |
2319 | ||
2320 | rb_erase(rb, &sis->swap_extent_root); | |
2321 | kfree(se); | |
2322 | } | |
2323 | ||
2324 | if (sis->flags & SWP_ACTIVATED) { | |
2325 | struct file *swap_file = sis->swap_file; | |
2326 | struct address_space *mapping = swap_file->f_mapping; | |
2327 | ||
2328 | sis->flags &= ~SWP_ACTIVATED; | |
2329 | if (mapping->a_ops->swap_deactivate) | |
2330 | mapping->a_ops->swap_deactivate(swap_file); | |
2331 | } | |
2332 | } | |
2333 | ||
2334 | /* | |
2335 | * Add a block range (and the corresponding page range) into this swapdev's | |
2336 | * extent tree. | |
2337 | * | |
2338 | * This function rather assumes that it is called in ascending page order. | |
2339 | */ | |
2340 | int | |
2341 | add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, | |
2342 | unsigned long nr_pages, sector_t start_block) | |
2343 | { | |
2344 | struct rb_node **link = &sis->swap_extent_root.rb_node, *parent = NULL; | |
2345 | struct swap_extent *se; | |
2346 | struct swap_extent *new_se; | |
2347 | ||
2348 | /* | |
2349 | * place the new node at the right most since the | |
2350 | * function is called in ascending page order. | |
2351 | */ | |
2352 | while (*link) { | |
2353 | parent = *link; | |
2354 | link = &parent->rb_right; | |
2355 | } | |
2356 | ||
2357 | if (parent) { | |
2358 | se = rb_entry(parent, struct swap_extent, rb_node); | |
2359 | BUG_ON(se->start_page + se->nr_pages != start_page); | |
2360 | if (se->start_block + se->nr_pages == start_block) { | |
2361 | /* Merge it */ | |
2362 | se->nr_pages += nr_pages; | |
2363 | return 0; | |
2364 | } | |
2365 | } | |
2366 | ||
2367 | /* No merge, insert a new extent. */ | |
2368 | new_se = kmalloc(sizeof(*se), GFP_KERNEL); | |
2369 | if (new_se == NULL) | |
2370 | return -ENOMEM; | |
2371 | new_se->start_page = start_page; | |
2372 | new_se->nr_pages = nr_pages; | |
2373 | new_se->start_block = start_block; | |
2374 | ||
2375 | rb_link_node(&new_se->rb_node, parent, link); | |
2376 | rb_insert_color(&new_se->rb_node, &sis->swap_extent_root); | |
2377 | return 1; | |
2378 | } | |
2379 | EXPORT_SYMBOL_GPL(add_swap_extent); | |
2380 | ||
2381 | /* | |
2382 | * A `swap extent' is a simple thing which maps a contiguous range of pages | |
2383 | * onto a contiguous range of disk blocks. An ordered list of swap extents | |
2384 | * is built at swapon time and is then used at swap_writepage/swap_readpage | |
2385 | * time for locating where on disk a page belongs. | |
2386 | * | |
2387 | * If the swapfile is an S_ISBLK block device, a single extent is installed. | |
2388 | * This is done so that the main operating code can treat S_ISBLK and S_ISREG | |
2389 | * swap files identically. | |
2390 | * | |
2391 | * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap | |
2392 | * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK | |
2393 | * swapfiles are handled *identically* after swapon time. | |
2394 | * | |
2395 | * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks | |
2396 | * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If | |
2397 | * some stray blocks are found which do not fall within the PAGE_SIZE alignment | |
2398 | * requirements, they are simply tossed out - we will never use those blocks | |
2399 | * for swapping. | |
2400 | * | |
2401 | * For all swap devices we set S_SWAPFILE across the life of the swapon. This | |
2402 | * prevents users from writing to the swap device, which will corrupt memory. | |
2403 | * | |
2404 | * The amount of disk space which a single swap extent represents varies. | |
2405 | * Typically it is in the 1-4 megabyte range. So we can have hundreds of | |
2406 | * extents in the list. To avoid much list walking, we cache the previous | |
2407 | * search location in `curr_swap_extent', and start new searches from there. | |
2408 | * This is extremely effective. The average number of iterations in | |
2409 | * map_swap_page() has been measured at about 0.3 per page. - akpm. | |
2410 | */ | |
2411 | static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) | |
2412 | { | |
2413 | struct file *swap_file = sis->swap_file; | |
2414 | struct address_space *mapping = swap_file->f_mapping; | |
2415 | struct inode *inode = mapping->host; | |
2416 | int ret; | |
2417 | ||
2418 | if (S_ISBLK(inode->i_mode)) { | |
2419 | ret = add_swap_extent(sis, 0, sis->max, 0); | |
2420 | *span = sis->pages; | |
2421 | return ret; | |
2422 | } | |
2423 | ||
2424 | if (mapping->a_ops->swap_activate) { | |
2425 | ret = mapping->a_ops->swap_activate(sis, swap_file, span); | |
2426 | if (ret >= 0) | |
2427 | sis->flags |= SWP_ACTIVATED; | |
2428 | if (!ret) { | |
2429 | sis->flags |= SWP_FS; | |
2430 | ret = add_swap_extent(sis, 0, sis->max, 0); | |
2431 | *span = sis->pages; | |
2432 | } | |
2433 | return ret; | |
2434 | } | |
2435 | ||
2436 | return generic_swapfile_activate(sis, swap_file, span); | |
2437 | } | |
2438 | ||
2439 | static int swap_node(struct swap_info_struct *p) | |
2440 | { | |
2441 | struct block_device *bdev; | |
2442 | ||
2443 | if (p->bdev) | |
2444 | bdev = p->bdev; | |
2445 | else | |
2446 | bdev = p->swap_file->f_inode->i_sb->s_bdev; | |
2447 | ||
2448 | return bdev ? bdev->bd_disk->node_id : NUMA_NO_NODE; | |
2449 | } | |
2450 | ||
2451 | static void setup_swap_info(struct swap_info_struct *p, int prio, | |
2452 | unsigned char *swap_map, | |
2453 | struct swap_cluster_info *cluster_info) | |
2454 | { | |
2455 | int i; | |
2456 | ||
2457 | if (prio >= 0) | |
2458 | p->prio = prio; | |
2459 | else | |
2460 | p->prio = --least_priority; | |
2461 | /* | |
2462 | * the plist prio is negated because plist ordering is | |
2463 | * low-to-high, while swap ordering is high-to-low | |
2464 | */ | |
2465 | p->list.prio = -p->prio; | |
2466 | for_each_node(i) { | |
2467 | if (p->prio >= 0) | |
2468 | p->avail_lists[i].prio = -p->prio; | |
2469 | else { | |
2470 | if (swap_node(p) == i) | |
2471 | p->avail_lists[i].prio = 1; | |
2472 | else | |
2473 | p->avail_lists[i].prio = -p->prio; | |
2474 | } | |
2475 | } | |
2476 | p->swap_map = swap_map; | |
2477 | p->cluster_info = cluster_info; | |
2478 | } | |
2479 | ||
2480 | static void _enable_swap_info(struct swap_info_struct *p) | |
2481 | { | |
2482 | p->flags |= SWP_WRITEOK | SWP_VALID; | |
2483 | atomic_long_add(p->pages, &nr_swap_pages); | |
2484 | total_swap_pages += p->pages; | |
2485 | ||
2486 | assert_spin_locked(&swap_lock); | |
2487 | /* | |
2488 | * both lists are plists, and thus priority ordered. | |
2489 | * swap_active_head needs to be priority ordered for swapoff(), | |
2490 | * which on removal of any swap_info_struct with an auto-assigned | |
2491 | * (i.e. negative) priority increments the auto-assigned priority | |
2492 | * of any lower-priority swap_info_structs. | |
2493 | * swap_avail_head needs to be priority ordered for get_swap_page(), | |
2494 | * which allocates swap pages from the highest available priority | |
2495 | * swap_info_struct. | |
2496 | */ | |
2497 | plist_add(&p->list, &swap_active_head); | |
2498 | add_to_avail_list(p); | |
2499 | } | |
2500 | ||
2501 | static void enable_swap_info(struct swap_info_struct *p, int prio, | |
2502 | unsigned char *swap_map, | |
2503 | struct swap_cluster_info *cluster_info, | |
2504 | unsigned long *frontswap_map) | |
2505 | { | |
2506 | frontswap_init(p->type, frontswap_map); | |
2507 | spin_lock(&swap_lock); | |
2508 | spin_lock(&p->lock); | |
2509 | setup_swap_info(p, prio, swap_map, cluster_info); | |
2510 | spin_unlock(&p->lock); | |
2511 | spin_unlock(&swap_lock); | |
2512 | /* | |
2513 | * Guarantee swap_map, cluster_info, etc. fields are valid | |
2514 | * between get/put_swap_device() if SWP_VALID bit is set | |
2515 | */ | |
2516 | synchronize_rcu(); | |
2517 | spin_lock(&swap_lock); | |
2518 | spin_lock(&p->lock); | |
2519 | _enable_swap_info(p); | |
2520 | spin_unlock(&p->lock); | |
2521 | spin_unlock(&swap_lock); | |
2522 | } | |
2523 | ||
2524 | static void reinsert_swap_info(struct swap_info_struct *p) | |
2525 | { | |
2526 | spin_lock(&swap_lock); | |
2527 | spin_lock(&p->lock); | |
2528 | setup_swap_info(p, p->prio, p->swap_map, p->cluster_info); | |
2529 | _enable_swap_info(p); | |
2530 | spin_unlock(&p->lock); | |
2531 | spin_unlock(&swap_lock); | |
2532 | } | |
2533 | ||
2534 | bool has_usable_swap(void) | |
2535 | { | |
2536 | bool ret = true; | |
2537 | ||
2538 | spin_lock(&swap_lock); | |
2539 | if (plist_head_empty(&swap_active_head)) | |
2540 | ret = false; | |
2541 | spin_unlock(&swap_lock); | |
2542 | return ret; | |
2543 | } | |
2544 | ||
2545 | SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) | |
2546 | { | |
2547 | struct swap_info_struct *p = NULL; | |
2548 | unsigned char *swap_map; | |
2549 | struct swap_cluster_info *cluster_info; | |
2550 | unsigned long *frontswap_map; | |
2551 | struct file *swap_file, *victim; | |
2552 | struct address_space *mapping; | |
2553 | struct inode *inode; | |
2554 | struct filename *pathname; | |
2555 | int err, found = 0; | |
2556 | unsigned int old_block_size; | |
2557 | ||
2558 | if (!capable(CAP_SYS_ADMIN)) | |
2559 | return -EPERM; | |
2560 | ||
2561 | BUG_ON(!current->mm); | |
2562 | ||
2563 | pathname = getname(specialfile); | |
2564 | if (IS_ERR(pathname)) | |
2565 | return PTR_ERR(pathname); | |
2566 | ||
2567 | victim = file_open_name(pathname, O_RDWR|O_LARGEFILE, 0); | |
2568 | err = PTR_ERR(victim); | |
2569 | if (IS_ERR(victim)) | |
2570 | goto out; | |
2571 | ||
2572 | mapping = victim->f_mapping; | |
2573 | spin_lock(&swap_lock); | |
2574 | plist_for_each_entry(p, &swap_active_head, list) { | |
2575 | if (p->flags & SWP_WRITEOK) { | |
2576 | if (p->swap_file->f_mapping == mapping) { | |
2577 | found = 1; | |
2578 | break; | |
2579 | } | |
2580 | } | |
2581 | } | |
2582 | if (!found) { | |
2583 | err = -EINVAL; | |
2584 | spin_unlock(&swap_lock); | |
2585 | goto out_dput; | |
2586 | } | |
2587 | if (!security_vm_enough_memory_mm(current->mm, p->pages)) | |
2588 | vm_unacct_memory(p->pages); | |
2589 | else { | |
2590 | err = -ENOMEM; | |
2591 | spin_unlock(&swap_lock); | |
2592 | goto out_dput; | |
2593 | } | |
2594 | del_from_avail_list(p); | |
2595 | spin_lock(&p->lock); | |
2596 | if (p->prio < 0) { | |
2597 | struct swap_info_struct *si = p; | |
2598 | int nid; | |
2599 | ||
2600 | plist_for_each_entry_continue(si, &swap_active_head, list) { | |
2601 | si->prio++; | |
2602 | si->list.prio--; | |
2603 | for_each_node(nid) { | |
2604 | if (si->avail_lists[nid].prio != 1) | |
2605 | si->avail_lists[nid].prio--; | |
2606 | } | |
2607 | } | |
2608 | least_priority++; | |
2609 | } | |
2610 | plist_del(&p->list, &swap_active_head); | |
2611 | atomic_long_sub(p->pages, &nr_swap_pages); | |
2612 | total_swap_pages -= p->pages; | |
2613 | p->flags &= ~SWP_WRITEOK; | |
2614 | spin_unlock(&p->lock); | |
2615 | spin_unlock(&swap_lock); | |
2616 | ||
2617 | disable_swap_slots_cache_lock(); | |
2618 | ||
2619 | set_current_oom_origin(); | |
2620 | err = try_to_unuse(p->type, false, 0); /* force unuse all pages */ | |
2621 | clear_current_oom_origin(); | |
2622 | ||
2623 | if (err) { | |
2624 | /* re-insert swap space back into swap_list */ | |
2625 | reinsert_swap_info(p); | |
2626 | reenable_swap_slots_cache_unlock(); | |
2627 | goto out_dput; | |
2628 | } | |
2629 | ||
2630 | reenable_swap_slots_cache_unlock(); | |
2631 | ||
2632 | spin_lock(&swap_lock); | |
2633 | spin_lock(&p->lock); | |
2634 | p->flags &= ~SWP_VALID; /* mark swap device as invalid */ | |
2635 | spin_unlock(&p->lock); | |
2636 | spin_unlock(&swap_lock); | |
2637 | /* | |
2638 | * wait for swap operations protected by get/put_swap_device() | |
2639 | * to complete | |
2640 | */ | |
2641 | synchronize_rcu(); | |
2642 | ||
2643 | flush_work(&p->discard_work); | |
2644 | ||
2645 | destroy_swap_extents(p); | |
2646 | if (p->flags & SWP_CONTINUED) | |
2647 | free_swap_count_continuations(p); | |
2648 | ||
2649 | if (!p->bdev || !blk_queue_nonrot(bdev_get_queue(p->bdev))) | |
2650 | atomic_dec(&nr_rotate_swap); | |
2651 | ||
2652 | mutex_lock(&swapon_mutex); | |
2653 | spin_lock(&swap_lock); | |
2654 | spin_lock(&p->lock); | |
2655 | drain_mmlist(); | |
2656 | ||
2657 | /* wait for anyone still in scan_swap_map */ | |
2658 | p->highest_bit = 0; /* cuts scans short */ | |
2659 | while (p->flags >= SWP_SCANNING) { | |
2660 | spin_unlock(&p->lock); | |
2661 | spin_unlock(&swap_lock); | |
2662 | schedule_timeout_uninterruptible(1); | |
2663 | spin_lock(&swap_lock); | |
2664 | spin_lock(&p->lock); | |
2665 | } | |
2666 | ||
2667 | swap_file = p->swap_file; | |
2668 | old_block_size = p->old_block_size; | |
2669 | p->swap_file = NULL; | |
2670 | p->max = 0; | |
2671 | swap_map = p->swap_map; | |
2672 | p->swap_map = NULL; | |
2673 | cluster_info = p->cluster_info; | |
2674 | p->cluster_info = NULL; | |
2675 | frontswap_map = frontswap_map_get(p); | |
2676 | spin_unlock(&p->lock); | |
2677 | spin_unlock(&swap_lock); | |
2678 | frontswap_invalidate_area(p->type); | |
2679 | frontswap_map_set(p, NULL); | |
2680 | mutex_unlock(&swapon_mutex); | |
2681 | free_percpu(p->percpu_cluster); | |
2682 | p->percpu_cluster = NULL; | |
2683 | free_percpu(p->cluster_next_cpu); | |
2684 | p->cluster_next_cpu = NULL; | |
2685 | vfree(swap_map); | |
2686 | kvfree(cluster_info); | |
2687 | kvfree(frontswap_map); | |
2688 | /* Destroy swap account information */ | |
2689 | swap_cgroup_swapoff(p->type); | |
2690 | exit_swap_address_space(p->type); | |
2691 | ||
2692 | inode = mapping->host; | |
2693 | if (S_ISBLK(inode->i_mode)) { | |
2694 | struct block_device *bdev = I_BDEV(inode); | |
2695 | ||
2696 | set_blocksize(bdev, old_block_size); | |
2697 | blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); | |
2698 | } | |
2699 | ||
2700 | inode_lock(inode); | |
2701 | inode->i_flags &= ~S_SWAPFILE; | |
2702 | inode_unlock(inode); | |
2703 | filp_close(swap_file, NULL); | |
2704 | ||
2705 | /* | |
2706 | * Clear the SWP_USED flag after all resources are freed so that swapon | |
2707 | * can reuse this swap_info in alloc_swap_info() safely. It is ok to | |
2708 | * not hold p->lock after we cleared its SWP_WRITEOK. | |
2709 | */ | |
2710 | spin_lock(&swap_lock); | |
2711 | p->flags = 0; | |
2712 | spin_unlock(&swap_lock); | |
2713 | ||
2714 | err = 0; | |
2715 | atomic_inc(&proc_poll_event); | |
2716 | wake_up_interruptible(&proc_poll_wait); | |
2717 | ||
2718 | out_dput: | |
2719 | filp_close(victim, NULL); | |
2720 | out: | |
2721 | putname(pathname); | |
2722 | return err; | |
2723 | } | |
2724 | ||
2725 | #ifdef CONFIG_PROC_FS | |
2726 | static __poll_t swaps_poll(struct file *file, poll_table *wait) | |
2727 | { | |
2728 | struct seq_file *seq = file->private_data; | |
2729 | ||
2730 | poll_wait(file, &proc_poll_wait, wait); | |
2731 | ||
2732 | if (seq->poll_event != atomic_read(&proc_poll_event)) { | |
2733 | seq->poll_event = atomic_read(&proc_poll_event); | |
2734 | return EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI; | |
2735 | } | |
2736 | ||
2737 | return EPOLLIN | EPOLLRDNORM; | |
2738 | } | |
2739 | ||
2740 | /* iterator */ | |
2741 | static void *swap_start(struct seq_file *swap, loff_t *pos) | |
2742 | { | |
2743 | struct swap_info_struct *si; | |
2744 | int type; | |
2745 | loff_t l = *pos; | |
2746 | ||
2747 | mutex_lock(&swapon_mutex); | |
2748 | ||
2749 | if (!l) | |
2750 | return SEQ_START_TOKEN; | |
2751 | ||
2752 | for (type = 0; (si = swap_type_to_swap_info(type)); type++) { | |
2753 | if (!(si->flags & SWP_USED) || !si->swap_map) | |
2754 | continue; | |
2755 | if (!--l) | |
2756 | return si; | |
2757 | } | |
2758 | ||
2759 | return NULL; | |
2760 | } | |
2761 | ||
2762 | static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) | |
2763 | { | |
2764 | struct swap_info_struct *si = v; | |
2765 | int type; | |
2766 | ||
2767 | if (v == SEQ_START_TOKEN) | |
2768 | type = 0; | |
2769 | else | |
2770 | type = si->type + 1; | |
2771 | ||
2772 | ++(*pos); | |
2773 | for (; (si = swap_type_to_swap_info(type)); type++) { | |
2774 | if (!(si->flags & SWP_USED) || !si->swap_map) | |
2775 | continue; | |
2776 | return si; | |
2777 | } | |
2778 | ||
2779 | return NULL; | |
2780 | } | |
2781 | ||
2782 | static void swap_stop(struct seq_file *swap, void *v) | |
2783 | { | |
2784 | mutex_unlock(&swapon_mutex); | |
2785 | } | |
2786 | ||
2787 | static int swap_show(struct seq_file *swap, void *v) | |
2788 | { | |
2789 | struct swap_info_struct *si = v; | |
2790 | struct file *file; | |
2791 | int len; | |
2792 | unsigned int bytes, inuse; | |
2793 | ||
2794 | if (si == SEQ_START_TOKEN) { | |
2795 | seq_puts(swap,"Filename\t\t\t\tType\t\tSize\t\tUsed\t\tPriority\n"); | |
2796 | return 0; | |
2797 | } | |
2798 | ||
2799 | bytes = si->pages << (PAGE_SHIFT - 10); | |
2800 | inuse = si->inuse_pages << (PAGE_SHIFT - 10); | |
2801 | ||
2802 | file = si->swap_file; | |
2803 | len = seq_file_path(swap, file, " \t\n\\"); | |
2804 | seq_printf(swap, "%*s%s\t%u\t%s%u\t%s%d\n", | |
2805 | len < 40 ? 40 - len : 1, " ", | |
2806 | S_ISBLK(file_inode(file)->i_mode) ? | |
2807 | "partition" : "file\t", | |
2808 | bytes, bytes < 10000000 ? "\t" : "", | |
2809 | inuse, inuse < 10000000 ? "\t" : "", | |
2810 | si->prio); | |
2811 | return 0; | |
2812 | } | |
2813 | ||
2814 | static const struct seq_operations swaps_op = { | |
2815 | .start = swap_start, | |
2816 | .next = swap_next, | |
2817 | .stop = swap_stop, | |
2818 | .show = swap_show | |
2819 | }; | |
2820 | ||
2821 | static int swaps_open(struct inode *inode, struct file *file) | |
2822 | { | |
2823 | struct seq_file *seq; | |
2824 | int ret; | |
2825 | ||
2826 | ret = seq_open(file, &swaps_op); | |
2827 | if (ret) | |
2828 | return ret; | |
2829 | ||
2830 | seq = file->private_data; | |
2831 | seq->poll_event = atomic_read(&proc_poll_event); | |
2832 | return 0; | |
2833 | } | |
2834 | ||
2835 | static const struct proc_ops swaps_proc_ops = { | |
2836 | .proc_flags = PROC_ENTRY_PERMANENT, | |
2837 | .proc_open = swaps_open, | |
2838 | .proc_read = seq_read, | |
2839 | .proc_lseek = seq_lseek, | |
2840 | .proc_release = seq_release, | |
2841 | .proc_poll = swaps_poll, | |
2842 | }; | |
2843 | ||
2844 | static int __init procswaps_init(void) | |
2845 | { | |
2846 | proc_create("swaps", 0, NULL, &swaps_proc_ops); | |
2847 | return 0; | |
2848 | } | |
2849 | __initcall(procswaps_init); | |
2850 | #endif /* CONFIG_PROC_FS */ | |
2851 | ||
2852 | #ifdef MAX_SWAPFILES_CHECK | |
2853 | static int __init max_swapfiles_check(void) | |
2854 | { | |
2855 | MAX_SWAPFILES_CHECK(); | |
2856 | return 0; | |
2857 | } | |
2858 | late_initcall(max_swapfiles_check); | |
2859 | #endif | |
2860 | ||
2861 | static struct swap_info_struct *alloc_swap_info(void) | |
2862 | { | |
2863 | struct swap_info_struct *p; | |
2864 | unsigned int type; | |
2865 | int i; | |
2866 | ||
2867 | p = kvzalloc(struct_size(p, avail_lists, nr_node_ids), GFP_KERNEL); | |
2868 | if (!p) | |
2869 | return ERR_PTR(-ENOMEM); | |
2870 | ||
2871 | spin_lock(&swap_lock); | |
2872 | for (type = 0; type < nr_swapfiles; type++) { | |
2873 | if (!(swap_info[type]->flags & SWP_USED)) | |
2874 | break; | |
2875 | } | |
2876 | if (type >= MAX_SWAPFILES) { | |
2877 | spin_unlock(&swap_lock); | |
2878 | kvfree(p); | |
2879 | return ERR_PTR(-EPERM); | |
2880 | } | |
2881 | if (type >= nr_swapfiles) { | |
2882 | p->type = type; | |
2883 | WRITE_ONCE(swap_info[type], p); | |
2884 | /* | |
2885 | * Write swap_info[type] before nr_swapfiles, in case a | |
2886 | * racing procfs swap_start() or swap_next() is reading them. | |
2887 | * (We never shrink nr_swapfiles, we never free this entry.) | |
2888 | */ | |
2889 | smp_wmb(); | |
2890 | WRITE_ONCE(nr_swapfiles, nr_swapfiles + 1); | |
2891 | } else { | |
2892 | kvfree(p); | |
2893 | p = swap_info[type]; | |
2894 | /* | |
2895 | * Do not memset this entry: a racing procfs swap_next() | |
2896 | * would be relying on p->type to remain valid. | |
2897 | */ | |
2898 | } | |
2899 | p->swap_extent_root = RB_ROOT; | |
2900 | plist_node_init(&p->list, 0); | |
2901 | for_each_node(i) | |
2902 | plist_node_init(&p->avail_lists[i], 0); | |
2903 | p->flags = SWP_USED; | |
2904 | spin_unlock(&swap_lock); | |
2905 | spin_lock_init(&p->lock); | |
2906 | spin_lock_init(&p->cont_lock); | |
2907 | ||
2908 | return p; | |
2909 | } | |
2910 | ||
2911 | static int claim_swapfile(struct swap_info_struct *p, struct inode *inode) | |
2912 | { | |
2913 | int error; | |
2914 | ||
2915 | if (S_ISBLK(inode->i_mode)) { | |
2916 | p->bdev = bdgrab(I_BDEV(inode)); | |
2917 | error = blkdev_get(p->bdev, | |
2918 | FMODE_READ | FMODE_WRITE | FMODE_EXCL, p); | |
2919 | if (error < 0) { | |
2920 | p->bdev = NULL; | |
2921 | return error; | |
2922 | } | |
2923 | p->old_block_size = block_size(p->bdev); | |
2924 | error = set_blocksize(p->bdev, PAGE_SIZE); | |
2925 | if (error < 0) | |
2926 | return error; | |
2927 | /* | |
2928 | * Zoned block devices contain zones that have a sequential | |
2929 | * write only restriction. Hence zoned block devices are not | |
2930 | * suitable for swapping. Disallow them here. | |
2931 | */ | |
2932 | if (blk_queue_is_zoned(p->bdev->bd_queue)) | |
2933 | return -EINVAL; | |
2934 | p->flags |= SWP_BLKDEV; | |
2935 | } else if (S_ISREG(inode->i_mode)) { | |
2936 | p->bdev = inode->i_sb->s_bdev; | |
2937 | } | |
2938 | ||
2939 | return 0; | |
2940 | } | |
2941 | ||
2942 | ||
2943 | /* | |
2944 | * Find out how many pages are allowed for a single swap device. There | |
2945 | * are two limiting factors: | |
2946 | * 1) the number of bits for the swap offset in the swp_entry_t type, and | |
2947 | * 2) the number of bits in the swap pte, as defined by the different | |
2948 | * architectures. | |
2949 | * | |
2950 | * In order to find the largest possible bit mask, a swap entry with | |
2951 | * swap type 0 and swap offset ~0UL is created, encoded to a swap pte, | |
2952 | * decoded to a swp_entry_t again, and finally the swap offset is | |
2953 | * extracted. | |
2954 | * | |
2955 | * This will mask all the bits from the initial ~0UL mask that can't | |
2956 | * be encoded in either the swp_entry_t or the architecture definition | |
2957 | * of a swap pte. | |
2958 | */ | |
2959 | unsigned long generic_max_swapfile_size(void) | |
2960 | { | |
2961 | return swp_offset(pte_to_swp_entry( | |
2962 | swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1; | |
2963 | } | |
2964 | ||
2965 | /* Can be overridden by an architecture for additional checks. */ | |
2966 | __weak unsigned long max_swapfile_size(void) | |
2967 | { | |
2968 | return generic_max_swapfile_size(); | |
2969 | } | |
2970 | ||
2971 | static unsigned long read_swap_header(struct swap_info_struct *p, | |
2972 | union swap_header *swap_header, | |
2973 | struct inode *inode) | |
2974 | { | |
2975 | int i; | |
2976 | unsigned long maxpages; | |
2977 | unsigned long swapfilepages; | |
2978 | unsigned long last_page; | |
2979 | ||
2980 | if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) { | |
2981 | pr_err("Unable to find swap-space signature\n"); | |
2982 | return 0; | |
2983 | } | |
2984 | ||
2985 | /* swap partition endianess hack... */ | |
2986 | if (swab32(swap_header->info.version) == 1) { | |
2987 | swab32s(&swap_header->info.version); | |
2988 | swab32s(&swap_header->info.last_page); | |
2989 | swab32s(&swap_header->info.nr_badpages); | |
2990 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) | |
2991 | return 0; | |
2992 | for (i = 0; i < swap_header->info.nr_badpages; i++) | |
2993 | swab32s(&swap_header->info.badpages[i]); | |
2994 | } | |
2995 | /* Check the swap header's sub-version */ | |
2996 | if (swap_header->info.version != 1) { | |
2997 | pr_warn("Unable to handle swap header version %d\n", | |
2998 | swap_header->info.version); | |
2999 | return 0; | |
3000 | } | |
3001 | ||
3002 | p->lowest_bit = 1; | |
3003 | p->cluster_next = 1; | |
3004 | p->cluster_nr = 0; | |
3005 | ||
3006 | maxpages = max_swapfile_size(); | |
3007 | last_page = swap_header->info.last_page; | |
3008 | if (!last_page) { | |
3009 | pr_warn("Empty swap-file\n"); | |
3010 | return 0; | |
3011 | } | |
3012 | if (last_page > maxpages) { | |
3013 | pr_warn("Truncating oversized swap area, only using %luk out of %luk\n", | |
3014 | maxpages << (PAGE_SHIFT - 10), | |
3015 | last_page << (PAGE_SHIFT - 10)); | |
3016 | } | |
3017 | if (maxpages > last_page) { | |
3018 | maxpages = last_page + 1; | |
3019 | /* p->max is an unsigned int: don't overflow it */ | |
3020 | if ((unsigned int)maxpages == 0) | |
3021 | maxpages = UINT_MAX; | |
3022 | } | |
3023 | p->highest_bit = maxpages - 1; | |
3024 | ||
3025 | if (!maxpages) | |
3026 | return 0; | |
3027 | swapfilepages = i_size_read(inode) >> PAGE_SHIFT; | |
3028 | if (swapfilepages && maxpages > swapfilepages) { | |
3029 | pr_warn("Swap area shorter than signature indicates\n"); | |
3030 | return 0; | |
3031 | } | |
3032 | if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) | |
3033 | return 0; | |
3034 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) | |
3035 | return 0; | |
3036 | ||
3037 | return maxpages; | |
3038 | } | |
3039 | ||
3040 | #define SWAP_CLUSTER_INFO_COLS \ | |
3041 | DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info)) | |
3042 | #define SWAP_CLUSTER_SPACE_COLS \ | |
3043 | DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER) | |
3044 | #define SWAP_CLUSTER_COLS \ | |
3045 | max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS) | |
3046 | ||
3047 | static int setup_swap_map_and_extents(struct swap_info_struct *p, | |
3048 | union swap_header *swap_header, | |
3049 | unsigned char *swap_map, | |
3050 | struct swap_cluster_info *cluster_info, | |
3051 | unsigned long maxpages, | |
3052 | sector_t *span) | |
3053 | { | |
3054 | unsigned int j, k; | |
3055 | unsigned int nr_good_pages; | |
3056 | int nr_extents; | |
3057 | unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); | |
3058 | unsigned long col = p->cluster_next / SWAPFILE_CLUSTER % SWAP_CLUSTER_COLS; | |
3059 | unsigned long i, idx; | |
3060 | ||
3061 | nr_good_pages = maxpages - 1; /* omit header page */ | |
3062 | ||
3063 | cluster_list_init(&p->free_clusters); | |
3064 | cluster_list_init(&p->discard_clusters); | |
3065 | ||
3066 | for (i = 0; i < swap_header->info.nr_badpages; i++) { | |
3067 | unsigned int page_nr = swap_header->info.badpages[i]; | |
3068 | if (page_nr == 0 || page_nr > swap_header->info.last_page) | |
3069 | return -EINVAL; | |
3070 | if (page_nr < maxpages) { | |
3071 | swap_map[page_nr] = SWAP_MAP_BAD; | |
3072 | nr_good_pages--; | |
3073 | /* | |
3074 | * Haven't marked the cluster free yet, no list | |
3075 | * operation involved | |
3076 | */ | |
3077 | inc_cluster_info_page(p, cluster_info, page_nr); | |
3078 | } | |
3079 | } | |
3080 | ||
3081 | /* Haven't marked the cluster free yet, no list operation involved */ | |
3082 | for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++) | |
3083 | inc_cluster_info_page(p, cluster_info, i); | |
3084 | ||
3085 | if (nr_good_pages) { | |
3086 | swap_map[0] = SWAP_MAP_BAD; | |
3087 | /* | |
3088 | * Not mark the cluster free yet, no list | |
3089 | * operation involved | |
3090 | */ | |
3091 | inc_cluster_info_page(p, cluster_info, 0); | |
3092 | p->max = maxpages; | |
3093 | p->pages = nr_good_pages; | |
3094 | nr_extents = setup_swap_extents(p, span); | |
3095 | if (nr_extents < 0) | |
3096 | return nr_extents; | |
3097 | nr_good_pages = p->pages; | |
3098 | } | |
3099 | if (!nr_good_pages) { | |
3100 | pr_warn("Empty swap-file\n"); | |
3101 | return -EINVAL; | |
3102 | } | |
3103 | ||
3104 | if (!cluster_info) | |
3105 | return nr_extents; | |
3106 | ||
3107 | ||
3108 | /* | |
3109 | * Reduce false cache line sharing between cluster_info and | |
3110 | * sharing same address space. | |
3111 | */ | |
3112 | for (k = 0; k < SWAP_CLUSTER_COLS; k++) { | |
3113 | j = (k + col) % SWAP_CLUSTER_COLS; | |
3114 | for (i = 0; i < DIV_ROUND_UP(nr_clusters, SWAP_CLUSTER_COLS); i++) { | |
3115 | idx = i * SWAP_CLUSTER_COLS + j; | |
3116 | if (idx >= nr_clusters) | |
3117 | continue; | |
3118 | if (cluster_count(&cluster_info[idx])) | |
3119 | continue; | |
3120 | cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE); | |
3121 | cluster_list_add_tail(&p->free_clusters, cluster_info, | |
3122 | idx); | |
3123 | } | |
3124 | } | |
3125 | return nr_extents; | |
3126 | } | |
3127 | ||
3128 | /* | |
3129 | * Helper to sys_swapon determining if a given swap | |
3130 | * backing device queue supports DISCARD operations. | |
3131 | */ | |
3132 | static bool swap_discardable(struct swap_info_struct *si) | |
3133 | { | |
3134 | struct request_queue *q = bdev_get_queue(si->bdev); | |
3135 | ||
3136 | if (!q || !blk_queue_discard(q)) | |
3137 | return false; | |
3138 | ||
3139 | return true; | |
3140 | } | |
3141 | ||
3142 | SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) | |
3143 | { | |
3144 | struct swap_info_struct *p; | |
3145 | struct filename *name; | |
3146 | struct file *swap_file = NULL; | |
3147 | struct address_space *mapping; | |
3148 | int prio; | |
3149 | int error; | |
3150 | union swap_header *swap_header; | |
3151 | int nr_extents; | |
3152 | sector_t span; | |
3153 | unsigned long maxpages; | |
3154 | unsigned char *swap_map = NULL; | |
3155 | struct swap_cluster_info *cluster_info = NULL; | |
3156 | unsigned long *frontswap_map = NULL; | |
3157 | struct page *page = NULL; | |
3158 | struct inode *inode = NULL; | |
3159 | bool inced_nr_rotate_swap = false; | |
3160 | ||
3161 | if (swap_flags & ~SWAP_FLAGS_VALID) | |
3162 | return -EINVAL; | |
3163 | ||
3164 | if (!capable(CAP_SYS_ADMIN)) | |
3165 | return -EPERM; | |
3166 | ||
3167 | if (!swap_avail_heads) | |
3168 | return -ENOMEM; | |
3169 | ||
3170 | p = alloc_swap_info(); | |
3171 | if (IS_ERR(p)) | |
3172 | return PTR_ERR(p); | |
3173 | ||
3174 | INIT_WORK(&p->discard_work, swap_discard_work); | |
3175 | ||
3176 | name = getname(specialfile); | |
3177 | if (IS_ERR(name)) { | |
3178 | error = PTR_ERR(name); | |
3179 | name = NULL; | |
3180 | goto bad_swap; | |
3181 | } | |
3182 | swap_file = file_open_name(name, O_RDWR|O_LARGEFILE, 0); | |
3183 | if (IS_ERR(swap_file)) { | |
3184 | error = PTR_ERR(swap_file); | |
3185 | swap_file = NULL; | |
3186 | goto bad_swap; | |
3187 | } | |
3188 | ||
3189 | p->swap_file = swap_file; | |
3190 | mapping = swap_file->f_mapping; | |
3191 | inode = mapping->host; | |
3192 | ||
3193 | error = claim_swapfile(p, inode); | |
3194 | if (unlikely(error)) | |
3195 | goto bad_swap; | |
3196 | ||
3197 | inode_lock(inode); | |
3198 | if (IS_SWAPFILE(inode)) { | |
3199 | error = -EBUSY; | |
3200 | goto bad_swap_unlock_inode; | |
3201 | } | |
3202 | ||
3203 | /* | |
3204 | * Read the swap header. | |
3205 | */ | |
3206 | if (!mapping->a_ops->readpage) { | |
3207 | error = -EINVAL; | |
3208 | goto bad_swap_unlock_inode; | |
3209 | } | |
3210 | page = read_mapping_page(mapping, 0, swap_file); | |
3211 | if (IS_ERR(page)) { | |
3212 | error = PTR_ERR(page); | |
3213 | goto bad_swap_unlock_inode; | |
3214 | } | |
3215 | swap_header = kmap(page); | |
3216 | ||
3217 | maxpages = read_swap_header(p, swap_header, inode); | |
3218 | if (unlikely(!maxpages)) { | |
3219 | error = -EINVAL; | |
3220 | goto bad_swap_unlock_inode; | |
3221 | } | |
3222 | ||
3223 | /* OK, set up the swap map and apply the bad block list */ | |
3224 | swap_map = vzalloc(maxpages); | |
3225 | if (!swap_map) { | |
3226 | error = -ENOMEM; | |
3227 | goto bad_swap_unlock_inode; | |
3228 | } | |
3229 | ||
3230 | if (bdi_cap_stable_pages_required(inode_to_bdi(inode))) | |
3231 | p->flags |= SWP_STABLE_WRITES; | |
3232 | ||
3233 | if (bdi_cap_synchronous_io(inode_to_bdi(inode))) | |
3234 | p->flags |= SWP_SYNCHRONOUS_IO; | |
3235 | ||
3236 | if (p->bdev && blk_queue_nonrot(bdev_get_queue(p->bdev))) { | |
3237 | int cpu; | |
3238 | unsigned long ci, nr_cluster; | |
3239 | ||
3240 | p->flags |= SWP_SOLIDSTATE; | |
3241 | p->cluster_next_cpu = alloc_percpu(unsigned int); | |
3242 | if (!p->cluster_next_cpu) { | |
3243 | error = -ENOMEM; | |
3244 | goto bad_swap_unlock_inode; | |
3245 | } | |
3246 | /* | |
3247 | * select a random position to start with to help wear leveling | |
3248 | * SSD | |
3249 | */ | |
3250 | for_each_possible_cpu(cpu) { | |
3251 | per_cpu(*p->cluster_next_cpu, cpu) = | |
3252 | 1 + prandom_u32_max(p->highest_bit); | |
3253 | } | |
3254 | nr_cluster = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); | |
3255 | ||
3256 | cluster_info = kvcalloc(nr_cluster, sizeof(*cluster_info), | |
3257 | GFP_KERNEL); | |
3258 | if (!cluster_info) { | |
3259 | error = -ENOMEM; | |
3260 | goto bad_swap_unlock_inode; | |
3261 | } | |
3262 | ||
3263 | for (ci = 0; ci < nr_cluster; ci++) | |
3264 | spin_lock_init(&((cluster_info + ci)->lock)); | |
3265 | ||
3266 | p->percpu_cluster = alloc_percpu(struct percpu_cluster); | |
3267 | if (!p->percpu_cluster) { | |
3268 | error = -ENOMEM; | |
3269 | goto bad_swap_unlock_inode; | |
3270 | } | |
3271 | for_each_possible_cpu(cpu) { | |
3272 | struct percpu_cluster *cluster; | |
3273 | cluster = per_cpu_ptr(p->percpu_cluster, cpu); | |
3274 | cluster_set_null(&cluster->index); | |
3275 | } | |
3276 | } else { | |
3277 | atomic_inc(&nr_rotate_swap); | |
3278 | inced_nr_rotate_swap = true; | |
3279 | } | |
3280 | ||
3281 | error = swap_cgroup_swapon(p->type, maxpages); | |
3282 | if (error) | |
3283 | goto bad_swap_unlock_inode; | |
3284 | ||
3285 | nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map, | |
3286 | cluster_info, maxpages, &span); | |
3287 | if (unlikely(nr_extents < 0)) { | |
3288 | error = nr_extents; | |
3289 | goto bad_swap_unlock_inode; | |
3290 | } | |
3291 | /* frontswap enabled? set up bit-per-page map for frontswap */ | |
3292 | if (IS_ENABLED(CONFIG_FRONTSWAP)) | |
3293 | frontswap_map = kvcalloc(BITS_TO_LONGS(maxpages), | |
3294 | sizeof(long), | |
3295 | GFP_KERNEL); | |
3296 | ||
3297 | if (p->bdev &&(swap_flags & SWAP_FLAG_DISCARD) && swap_discardable(p)) { | |
3298 | /* | |
3299 | * When discard is enabled for swap with no particular | |
3300 | * policy flagged, we set all swap discard flags here in | |
3301 | * order to sustain backward compatibility with older | |
3302 | * swapon(8) releases. | |
3303 | */ | |
3304 | p->flags |= (SWP_DISCARDABLE | SWP_AREA_DISCARD | | |
3305 | SWP_PAGE_DISCARD); | |
3306 | ||
3307 | /* | |
3308 | * By flagging sys_swapon, a sysadmin can tell us to | |
3309 | * either do single-time area discards only, or to just | |
3310 | * perform discards for released swap page-clusters. | |
3311 | * Now it's time to adjust the p->flags accordingly. | |
3312 | */ | |
3313 | if (swap_flags & SWAP_FLAG_DISCARD_ONCE) | |
3314 | p->flags &= ~SWP_PAGE_DISCARD; | |
3315 | else if (swap_flags & SWAP_FLAG_DISCARD_PAGES) | |
3316 | p->flags &= ~SWP_AREA_DISCARD; | |
3317 | ||
3318 | /* issue a swapon-time discard if it's still required */ | |
3319 | if (p->flags & SWP_AREA_DISCARD) { | |
3320 | int err = discard_swap(p); | |
3321 | if (unlikely(err)) | |
3322 | pr_err("swapon: discard_swap(%p): %d\n", | |
3323 | p, err); | |
3324 | } | |
3325 | } | |
3326 | ||
3327 | error = init_swap_address_space(p->type, maxpages); | |
3328 | if (error) | |
3329 | goto bad_swap_unlock_inode; | |
3330 | ||
3331 | /* | |
3332 | * Flush any pending IO and dirty mappings before we start using this | |
3333 | * swap device. | |
3334 | */ | |
3335 | inode->i_flags |= S_SWAPFILE; | |
3336 | error = inode_drain_writes(inode); | |
3337 | if (error) { | |
3338 | inode->i_flags &= ~S_SWAPFILE; | |
3339 | goto bad_swap_unlock_inode; | |
3340 | } | |
3341 | ||
3342 | mutex_lock(&swapon_mutex); | |
3343 | prio = -1; | |
3344 | if (swap_flags & SWAP_FLAG_PREFER) | |
3345 | prio = | |
3346 | (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT; | |
3347 | enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map); | |
3348 | ||
3349 | pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s%s\n", | |
3350 | p->pages<<(PAGE_SHIFT-10), name->name, p->prio, | |
3351 | nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10), | |
3352 | (p->flags & SWP_SOLIDSTATE) ? "SS" : "", | |
3353 | (p->flags & SWP_DISCARDABLE) ? "D" : "", | |
3354 | (p->flags & SWP_AREA_DISCARD) ? "s" : "", | |
3355 | (p->flags & SWP_PAGE_DISCARD) ? "c" : "", | |
3356 | (frontswap_map) ? "FS" : ""); | |
3357 | ||
3358 | mutex_unlock(&swapon_mutex); | |
3359 | atomic_inc(&proc_poll_event); | |
3360 | wake_up_interruptible(&proc_poll_wait); | |
3361 | ||
3362 | error = 0; | |
3363 | goto out; | |
3364 | bad_swap_unlock_inode: | |
3365 | inode_unlock(inode); | |
3366 | bad_swap: | |
3367 | free_percpu(p->percpu_cluster); | |
3368 | p->percpu_cluster = NULL; | |
3369 | free_percpu(p->cluster_next_cpu); | |
3370 | p->cluster_next_cpu = NULL; | |
3371 | if (inode && S_ISBLK(inode->i_mode) && p->bdev) { | |
3372 | set_blocksize(p->bdev, p->old_block_size); | |
3373 | blkdev_put(p->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); | |
3374 | } | |
3375 | inode = NULL; | |
3376 | destroy_swap_extents(p); | |
3377 | swap_cgroup_swapoff(p->type); | |
3378 | spin_lock(&swap_lock); | |
3379 | p->swap_file = NULL; | |
3380 | p->flags = 0; | |
3381 | spin_unlock(&swap_lock); | |
3382 | vfree(swap_map); | |
3383 | kvfree(cluster_info); | |
3384 | kvfree(frontswap_map); | |
3385 | if (inced_nr_rotate_swap) | |
3386 | atomic_dec(&nr_rotate_swap); | |
3387 | if (swap_file) | |
3388 | filp_close(swap_file, NULL); | |
3389 | out: | |
3390 | if (page && !IS_ERR(page)) { | |
3391 | kunmap(page); | |
3392 | put_page(page); | |
3393 | } | |
3394 | if (name) | |
3395 | putname(name); | |
3396 | if (inode) | |
3397 | inode_unlock(inode); | |
3398 | if (!error) | |
3399 | enable_swap_slots_cache(); | |
3400 | return error; | |
3401 | } | |
3402 | ||
3403 | void si_swapinfo(struct sysinfo *val) | |
3404 | { | |
3405 | unsigned int type; | |
3406 | unsigned long nr_to_be_unused = 0; | |
3407 | ||
3408 | spin_lock(&swap_lock); | |
3409 | for (type = 0; type < nr_swapfiles; type++) { | |
3410 | struct swap_info_struct *si = swap_info[type]; | |
3411 | ||
3412 | if ((si->flags & SWP_USED) && !(si->flags & SWP_WRITEOK)) | |
3413 | nr_to_be_unused += si->inuse_pages; | |
3414 | } | |
3415 | val->freeswap = atomic_long_read(&nr_swap_pages) + nr_to_be_unused; | |
3416 | val->totalswap = total_swap_pages + nr_to_be_unused; | |
3417 | spin_unlock(&swap_lock); | |
3418 | } | |
3419 | ||
3420 | /* | |
3421 | * Verify that a swap entry is valid and increment its swap map count. | |
3422 | * | |
3423 | * Returns error code in following case. | |
3424 | * - success -> 0 | |
3425 | * - swp_entry is invalid -> EINVAL | |
3426 | * - swp_entry is migration entry -> EINVAL | |
3427 | * - swap-cache reference is requested but there is already one. -> EEXIST | |
3428 | * - swap-cache reference is requested but the entry is not used. -> ENOENT | |
3429 | * - swap-mapped reference requested but needs continued swap count. -> ENOMEM | |
3430 | */ | |
3431 | static int __swap_duplicate(swp_entry_t entry, unsigned char usage) | |
3432 | { | |
3433 | struct swap_info_struct *p; | |
3434 | struct swap_cluster_info *ci; | |
3435 | unsigned long offset; | |
3436 | unsigned char count; | |
3437 | unsigned char has_cache; | |
3438 | int err = -EINVAL; | |
3439 | ||
3440 | p = get_swap_device(entry); | |
3441 | if (!p) | |
3442 | goto out; | |
3443 | ||
3444 | offset = swp_offset(entry); | |
3445 | ci = lock_cluster_or_swap_info(p, offset); | |
3446 | ||
3447 | count = p->swap_map[offset]; | |
3448 | ||
3449 | /* | |
3450 | * swapin_readahead() doesn't check if a swap entry is valid, so the | |
3451 | * swap entry could be SWAP_MAP_BAD. Check here with lock held. | |
3452 | */ | |
3453 | if (unlikely(swap_count(count) == SWAP_MAP_BAD)) { | |
3454 | err = -ENOENT; | |
3455 | goto unlock_out; | |
3456 | } | |
3457 | ||
3458 | has_cache = count & SWAP_HAS_CACHE; | |
3459 | count &= ~SWAP_HAS_CACHE; | |
3460 | err = 0; | |
3461 | ||
3462 | if (usage == SWAP_HAS_CACHE) { | |
3463 | ||
3464 | /* set SWAP_HAS_CACHE if there is no cache and entry is used */ | |
3465 | if (!has_cache && count) | |
3466 | has_cache = SWAP_HAS_CACHE; | |
3467 | else if (has_cache) /* someone else added cache */ | |
3468 | err = -EEXIST; | |
3469 | else /* no users remaining */ | |
3470 | err = -ENOENT; | |
3471 | ||
3472 | } else if (count || has_cache) { | |
3473 | ||
3474 | if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX) | |
3475 | count += usage; | |
3476 | else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX) | |
3477 | err = -EINVAL; | |
3478 | else if (swap_count_continued(p, offset, count)) | |
3479 | count = COUNT_CONTINUED; | |
3480 | else | |
3481 | err = -ENOMEM; | |
3482 | } else | |
3483 | err = -ENOENT; /* unused swap entry */ | |
3484 | ||
3485 | p->swap_map[offset] = count | has_cache; | |
3486 | ||
3487 | unlock_out: | |
3488 | unlock_cluster_or_swap_info(p, ci); | |
3489 | out: | |
3490 | if (p) | |
3491 | put_swap_device(p); | |
3492 | return err; | |
3493 | } | |
3494 | ||
3495 | /* | |
3496 | * Help swapoff by noting that swap entry belongs to shmem/tmpfs | |
3497 | * (in which case its reference count is never incremented). | |
3498 | */ | |
3499 | void swap_shmem_alloc(swp_entry_t entry) | |
3500 | { | |
3501 | __swap_duplicate(entry, SWAP_MAP_SHMEM); | |
3502 | } | |
3503 | ||
3504 | /* | |
3505 | * Increase reference count of swap entry by 1. | |
3506 | * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required | |
3507 | * but could not be atomically allocated. Returns 0, just as if it succeeded, | |
3508 | * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which | |
3509 | * might occur if a page table entry has got corrupted. | |
3510 | */ | |
3511 | int swap_duplicate(swp_entry_t entry) | |
3512 | { | |
3513 | int err = 0; | |
3514 | ||
3515 | while (!err && __swap_duplicate(entry, 1) == -ENOMEM) | |
3516 | err = add_swap_count_continuation(entry, GFP_ATOMIC); | |
3517 | return err; | |
3518 | } | |
3519 | ||
3520 | /* | |
3521 | * @entry: swap entry for which we allocate swap cache. | |
3522 | * | |
3523 | * Called when allocating swap cache for existing swap entry, | |
3524 | * This can return error codes. Returns 0 at success. | |
3525 | * -EEXIST means there is a swap cache. | |
3526 | * Note: return code is different from swap_duplicate(). | |
3527 | */ | |
3528 | int swapcache_prepare(swp_entry_t entry) | |
3529 | { | |
3530 | return __swap_duplicate(entry, SWAP_HAS_CACHE); | |
3531 | } | |
3532 | ||
3533 | struct swap_info_struct *swp_swap_info(swp_entry_t entry) | |
3534 | { | |
3535 | return swap_type_to_swap_info(swp_type(entry)); | |
3536 | } | |
3537 | ||
3538 | struct swap_info_struct *page_swap_info(struct page *page) | |
3539 | { | |
3540 | swp_entry_t entry = { .val = page_private(page) }; | |
3541 | return swp_swap_info(entry); | |
3542 | } | |
3543 | ||
3544 | /* | |
3545 | * out-of-line __page_file_ methods to avoid include hell. | |
3546 | */ | |
3547 | struct address_space *__page_file_mapping(struct page *page) | |
3548 | { | |
3549 | return page_swap_info(page)->swap_file->f_mapping; | |
3550 | } | |
3551 | EXPORT_SYMBOL_GPL(__page_file_mapping); | |
3552 | ||
3553 | pgoff_t __page_file_index(struct page *page) | |
3554 | { | |
3555 | swp_entry_t swap = { .val = page_private(page) }; | |
3556 | return swp_offset(swap); | |
3557 | } | |
3558 | EXPORT_SYMBOL_GPL(__page_file_index); | |
3559 | ||
3560 | /* | |
3561 | * add_swap_count_continuation - called when a swap count is duplicated | |
3562 | * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's | |
3563 | * page of the original vmalloc'ed swap_map, to hold the continuation count | |
3564 | * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called | |
3565 | * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc. | |
3566 | * | |
3567 | * These continuation pages are seldom referenced: the common paths all work | |
3568 | * on the original swap_map, only referring to a continuation page when the | |
3569 | * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX. | |
3570 | * | |
3571 | * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding | |
3572 | * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL) | |
3573 | * can be called after dropping locks. | |
3574 | */ | |
3575 | int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask) | |
3576 | { | |
3577 | struct swap_info_struct *si; | |
3578 | struct swap_cluster_info *ci; | |
3579 | struct page *head; | |
3580 | struct page *page; | |
3581 | struct page *list_page; | |
3582 | pgoff_t offset; | |
3583 | unsigned char count; | |
3584 | int ret = 0; | |
3585 | ||
3586 | /* | |
3587 | * When debugging, it's easier to use __GFP_ZERO here; but it's better | |
3588 | * for latency not to zero a page while GFP_ATOMIC and holding locks. | |
3589 | */ | |
3590 | page = alloc_page(gfp_mask | __GFP_HIGHMEM); | |
3591 | ||
3592 | si = get_swap_device(entry); | |
3593 | if (!si) { | |
3594 | /* | |
3595 | * An acceptable race has occurred since the failing | |
3596 | * __swap_duplicate(): the swap device may be swapoff | |
3597 | */ | |
3598 | goto outer; | |
3599 | } | |
3600 | spin_lock(&si->lock); | |
3601 | ||
3602 | offset = swp_offset(entry); | |
3603 | ||
3604 | ci = lock_cluster(si, offset); | |
3605 | ||
3606 | count = si->swap_map[offset] & ~SWAP_HAS_CACHE; | |
3607 | ||
3608 | if ((count & ~COUNT_CONTINUED) != SWAP_MAP_MAX) { | |
3609 | /* | |
3610 | * The higher the swap count, the more likely it is that tasks | |
3611 | * will race to add swap count continuation: we need to avoid | |
3612 | * over-provisioning. | |
3613 | */ | |
3614 | goto out; | |
3615 | } | |
3616 | ||
3617 | if (!page) { | |
3618 | ret = -ENOMEM; | |
3619 | goto out; | |
3620 | } | |
3621 | ||
3622 | /* | |
3623 | * We are fortunate that although vmalloc_to_page uses pte_offset_map, | |
3624 | * no architecture is using highmem pages for kernel page tables: so it | |
3625 | * will not corrupt the GFP_ATOMIC caller's atomic page table kmaps. | |
3626 | */ | |
3627 | head = vmalloc_to_page(si->swap_map + offset); | |
3628 | offset &= ~PAGE_MASK; | |
3629 | ||
3630 | spin_lock(&si->cont_lock); | |
3631 | /* | |
3632 | * Page allocation does not initialize the page's lru field, | |
3633 | * but it does always reset its private field. | |
3634 | */ | |
3635 | if (!page_private(head)) { | |
3636 | BUG_ON(count & COUNT_CONTINUED); | |
3637 | INIT_LIST_HEAD(&head->lru); | |
3638 | set_page_private(head, SWP_CONTINUED); | |
3639 | si->flags |= SWP_CONTINUED; | |
3640 | } | |
3641 | ||
3642 | list_for_each_entry(list_page, &head->lru, lru) { | |
3643 | unsigned char *map; | |
3644 | ||
3645 | /* | |
3646 | * If the previous map said no continuation, but we've found | |
3647 | * a continuation page, free our allocation and use this one. | |
3648 | */ | |
3649 | if (!(count & COUNT_CONTINUED)) | |
3650 | goto out_unlock_cont; | |
3651 | ||
3652 | map = kmap_atomic(list_page) + offset; | |
3653 | count = *map; | |
3654 | kunmap_atomic(map); | |
3655 | ||
3656 | /* | |
3657 | * If this continuation count now has some space in it, | |
3658 | * free our allocation and use this one. | |
3659 | */ | |
3660 | if ((count & ~COUNT_CONTINUED) != SWAP_CONT_MAX) | |
3661 | goto out_unlock_cont; | |
3662 | } | |
3663 | ||
3664 | list_add_tail(&page->lru, &head->lru); | |
3665 | page = NULL; /* now it's attached, don't free it */ | |
3666 | out_unlock_cont: | |
3667 | spin_unlock(&si->cont_lock); | |
3668 | out: | |
3669 | unlock_cluster(ci); | |
3670 | spin_unlock(&si->lock); | |
3671 | put_swap_device(si); | |
3672 | outer: | |
3673 | if (page) | |
3674 | __free_page(page); | |
3675 | return ret; | |
3676 | } | |
3677 | ||
3678 | /* | |
3679 | * swap_count_continued - when the original swap_map count is incremented | |
3680 | * from SWAP_MAP_MAX, check if there is already a continuation page to carry | |
3681 | * into, carry if so, or else fail until a new continuation page is allocated; | |
3682 | * when the original swap_map count is decremented from 0 with continuation, | |
3683 | * borrow from the continuation and report whether it still holds more. | |
3684 | * Called while __swap_duplicate() or swap_entry_free() holds swap or cluster | |
3685 | * lock. | |
3686 | */ | |
3687 | static bool swap_count_continued(struct swap_info_struct *si, | |
3688 | pgoff_t offset, unsigned char count) | |
3689 | { | |
3690 | struct page *head; | |
3691 | struct page *page; | |
3692 | unsigned char *map; | |
3693 | bool ret; | |
3694 | ||
3695 | head = vmalloc_to_page(si->swap_map + offset); | |
3696 | if (page_private(head) != SWP_CONTINUED) { | |
3697 | BUG_ON(count & COUNT_CONTINUED); | |
3698 | return false; /* need to add count continuation */ | |
3699 | } | |
3700 | ||
3701 | spin_lock(&si->cont_lock); | |
3702 | offset &= ~PAGE_MASK; | |
3703 | page = list_next_entry(head, lru); | |
3704 | map = kmap_atomic(page) + offset; | |
3705 | ||
3706 | if (count == SWAP_MAP_MAX) /* initial increment from swap_map */ | |
3707 | goto init_map; /* jump over SWAP_CONT_MAX checks */ | |
3708 | ||
3709 | if (count == (SWAP_MAP_MAX | COUNT_CONTINUED)) { /* incrementing */ | |
3710 | /* | |
3711 | * Think of how you add 1 to 999 | |
3712 | */ | |
3713 | while (*map == (SWAP_CONT_MAX | COUNT_CONTINUED)) { | |
3714 | kunmap_atomic(map); | |
3715 | page = list_next_entry(page, lru); | |
3716 | BUG_ON(page == head); | |
3717 | map = kmap_atomic(page) + offset; | |
3718 | } | |
3719 | if (*map == SWAP_CONT_MAX) { | |
3720 | kunmap_atomic(map); | |
3721 | page = list_next_entry(page, lru); | |
3722 | if (page == head) { | |
3723 | ret = false; /* add count continuation */ | |
3724 | goto out; | |
3725 | } | |
3726 | map = kmap_atomic(page) + offset; | |
3727 | init_map: *map = 0; /* we didn't zero the page */ | |
3728 | } | |
3729 | *map += 1; | |
3730 | kunmap_atomic(map); | |
3731 | while ((page = list_prev_entry(page, lru)) != head) { | |
3732 | map = kmap_atomic(page) + offset; | |
3733 | *map = COUNT_CONTINUED; | |
3734 | kunmap_atomic(map); | |
3735 | } | |
3736 | ret = true; /* incremented */ | |
3737 | ||
3738 | } else { /* decrementing */ | |
3739 | /* | |
3740 | * Think of how you subtract 1 from 1000 | |
3741 | */ | |
3742 | BUG_ON(count != COUNT_CONTINUED); | |
3743 | while (*map == COUNT_CONTINUED) { | |
3744 | kunmap_atomic(map); | |
3745 | page = list_next_entry(page, lru); | |
3746 | BUG_ON(page == head); | |
3747 | map = kmap_atomic(page) + offset; | |
3748 | } | |
3749 | BUG_ON(*map == 0); | |
3750 | *map -= 1; | |
3751 | if (*map == 0) | |
3752 | count = 0; | |
3753 | kunmap_atomic(map); | |
3754 | while ((page = list_prev_entry(page, lru)) != head) { | |
3755 | map = kmap_atomic(page) + offset; | |
3756 | *map = SWAP_CONT_MAX | count; | |
3757 | count = COUNT_CONTINUED; | |
3758 | kunmap_atomic(map); | |
3759 | } | |
3760 | ret = count == COUNT_CONTINUED; | |
3761 | } | |
3762 | out: | |
3763 | spin_unlock(&si->cont_lock); | |
3764 | return ret; | |
3765 | } | |
3766 | ||
3767 | /* | |
3768 | * free_swap_count_continuations - swapoff free all the continuation pages | |
3769 | * appended to the swap_map, after swap_map is quiesced, before vfree'ing it. | |
3770 | */ | |
3771 | static void free_swap_count_continuations(struct swap_info_struct *si) | |
3772 | { | |
3773 | pgoff_t offset; | |
3774 | ||
3775 | for (offset = 0; offset < si->max; offset += PAGE_SIZE) { | |
3776 | struct page *head; | |
3777 | head = vmalloc_to_page(si->swap_map + offset); | |
3778 | if (page_private(head)) { | |
3779 | struct page *page, *next; | |
3780 | ||
3781 | list_for_each_entry_safe(page, next, &head->lru, lru) { | |
3782 | list_del(&page->lru); | |
3783 | __free_page(page); | |
3784 | } | |
3785 | } | |
3786 | } | |
3787 | } | |
3788 | ||
3789 | #if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP) | |
3790 | void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask) | |
3791 | { | |
3792 | struct swap_info_struct *si, *next; | |
3793 | int nid = page_to_nid(page); | |
3794 | ||
3795 | if (!(gfp_mask & __GFP_IO)) | |
3796 | return; | |
3797 | ||
3798 | if (!blk_cgroup_congested()) | |
3799 | return; | |
3800 | ||
3801 | /* | |
3802 | * We've already scheduled a throttle, avoid taking the global swap | |
3803 | * lock. | |
3804 | */ | |
3805 | if (current->throttle_queue) | |
3806 | return; | |
3807 | ||
3808 | spin_lock(&swap_avail_lock); | |
3809 | plist_for_each_entry_safe(si, next, &swap_avail_heads[nid], | |
3810 | avail_lists[nid]) { | |
3811 | if (si->bdev) { | |
3812 | blkcg_schedule_throttle(bdev_get_queue(si->bdev), true); | |
3813 | break; | |
3814 | } | |
3815 | } | |
3816 | spin_unlock(&swap_avail_lock); | |
3817 | } | |
3818 | #endif | |
3819 | ||
3820 | static int __init swapfile_init(void) | |
3821 | { | |
3822 | int nid; | |
3823 | ||
3824 | swap_avail_heads = kmalloc_array(nr_node_ids, sizeof(struct plist_head), | |
3825 | GFP_KERNEL); | |
3826 | if (!swap_avail_heads) { | |
3827 | pr_emerg("Not enough memory for swap heads, swap is disabled\n"); | |
3828 | return -ENOMEM; | |
3829 | } | |
3830 | ||
3831 | for_each_node(nid) | |
3832 | plist_head_init(&swap_avail_heads[nid]); | |
3833 | ||
3834 | return 0; | |
3835 | } | |
3836 | subsys_initcall(swapfile_init); |