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/blkdev.h> |
10 | #include <linux/mm.h> |
11 | #include <linux/sched/mm.h> |
12 | #include <linux/sched/task.h> |
13 | #include <linux/hugetlb.h> |
14 | #include <linux/mman.h> |
15 | #include <linux/slab.h> |
16 | #include <linux/kernel_stat.h> |
17 | #include <linux/swap.h> |
18 | #include <linux/vmalloc.h> |
19 | #include <linux/pagemap.h> |
20 | #include <linux/namei.h> |
21 | #include <linux/shmem_fs.h> |
22 | #include <linux/blk-cgroup.h> |
23 | #include <linux/random.h> |
24 | #include <linux/writeback.h> |
25 | #include <linux/proc_fs.h> |
26 | #include <linux/seq_file.h> |
27 | #include <linux/init.h> |
28 | #include <linux/ksm.h> |
29 | #include <linux/rmap.h> |
30 | #include <linux/security.h> |
31 | #include <linux/backing-dev.h> |
32 | #include <linux/mutex.h> |
33 | #include <linux/capability.h> |
34 | #include <linux/syscalls.h> |
35 | #include <linux/memcontrol.h> |
36 | #include <linux/poll.h> |
37 | #include <linux/oom.h> |
38 | #include <linux/swapfile.h> |
39 | #include <linux/export.h> |
40 | #include <linux/swap_slots.h> |
41 | #include <linux/sort.h> |
42 | #include <linux/completion.h> |
43 | #include <linux/suspend.h> |
44 | #include <linux/zswap.h> |
45 | |
46 | #include <asm/tlbflush.h> |
47 | #include <linux/swapops.h> |
48 | #include <linux/swap_cgroup.h> |
49 | #include "internal.h" |
50 | #include "swap.h" |
51 | |
52 | static bool swap_count_continued(struct swap_info_struct *, pgoff_t, |
53 | unsigned char); |
54 | static void free_swap_count_continuations(struct swap_info_struct *); |
55 | |
56 | static DEFINE_SPINLOCK(swap_lock); |
57 | static unsigned int nr_swapfiles; |
58 | atomic_long_t nr_swap_pages; |
59 | /* |
60 | * Some modules use swappable objects and may try to swap them out under |
61 | * memory pressure (via the shrinker). Before doing so, they may wish to |
62 | * check to see if any swap space is available. |
63 | */ |
64 | EXPORT_SYMBOL_GPL(nr_swap_pages); |
65 | /* protected with swap_lock. reading in vm_swap_full() doesn't need lock */ |
66 | long total_swap_pages; |
67 | static int least_priority = -1; |
68 | unsigned long swapfile_maximum_size; |
69 | #ifdef CONFIG_MIGRATION |
70 | bool swap_migration_ad_supported; |
71 | #endif /* CONFIG_MIGRATION */ |
72 | |
73 | static const char Bad_file[] = "Bad swap file entry " ; |
74 | static const char Unused_file[] = "Unused swap file entry " ; |
75 | static const char Bad_offset[] = "Bad swap offset entry " ; |
76 | static const char Unused_offset[] = "Unused swap offset entry " ; |
77 | |
78 | /* |
79 | * all active swap_info_structs |
80 | * protected with swap_lock, and ordered by priority. |
81 | */ |
82 | static PLIST_HEAD(swap_active_head); |
83 | |
84 | /* |
85 | * all available (active, not full) swap_info_structs |
86 | * protected with swap_avail_lock, ordered by priority. |
87 | * This is used by folio_alloc_swap() instead of swap_active_head |
88 | * because swap_active_head includes all swap_info_structs, |
89 | * but folio_alloc_swap() doesn't need to look at full ones. |
90 | * This uses its own lock instead of swap_lock because when a |
91 | * swap_info_struct changes between not-full/full, it needs to |
92 | * add/remove itself to/from this list, but the swap_info_struct->lock |
93 | * is held and the locking order requires swap_lock to be taken |
94 | * before any swap_info_struct->lock. |
95 | */ |
96 | static struct plist_head *swap_avail_heads; |
97 | static DEFINE_SPINLOCK(swap_avail_lock); |
98 | |
99 | static struct swap_info_struct *swap_info[MAX_SWAPFILES]; |
100 | |
101 | static DEFINE_MUTEX(swapon_mutex); |
102 | |
103 | static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait); |
104 | /* Activity counter to indicate that a swapon or swapoff has occurred */ |
105 | static atomic_t proc_poll_event = ATOMIC_INIT(0); |
106 | |
107 | atomic_t nr_rotate_swap = ATOMIC_INIT(0); |
108 | |
109 | static struct swap_info_struct *swap_type_to_swap_info(int type) |
110 | { |
111 | if (type >= MAX_SWAPFILES) |
112 | return NULL; |
113 | |
114 | return READ_ONCE(swap_info[type]); /* rcu_dereference() */ |
115 | } |
116 | |
117 | static inline unsigned char swap_count(unsigned char ent) |
118 | { |
119 | return ent & ~SWAP_HAS_CACHE; /* may include COUNT_CONTINUED flag */ |
120 | } |
121 | |
122 | /* Reclaim the swap entry anyway if possible */ |
123 | #define TTRS_ANYWAY 0x1 |
124 | /* |
125 | * Reclaim the swap entry if there are no more mappings of the |
126 | * corresponding page |
127 | */ |
128 | #define TTRS_UNMAPPED 0x2 |
129 | /* Reclaim the swap entry if swap is getting full*/ |
130 | #define TTRS_FULL 0x4 |
131 | |
132 | /* returns 1 if swap entry is freed */ |
133 | static int __try_to_reclaim_swap(struct swap_info_struct *si, |
134 | unsigned long offset, unsigned long flags) |
135 | { |
136 | swp_entry_t entry = swp_entry(type: si->type, offset); |
137 | struct folio *folio; |
138 | int ret = 0; |
139 | |
140 | folio = filemap_get_folio(swap_address_space(entry), index: offset); |
141 | if (IS_ERR(ptr: folio)) |
142 | return 0; |
143 | /* |
144 | * When this function is called from scan_swap_map_slots() and it's |
145 | * called by vmscan.c at reclaiming folios. So we hold a folio lock |
146 | * here. We have to use trylock for avoiding deadlock. This is a special |
147 | * case and you should use folio_free_swap() with explicit folio_lock() |
148 | * in usual operations. |
149 | */ |
150 | if (folio_trylock(folio)) { |
151 | if ((flags & TTRS_ANYWAY) || |
152 | ((flags & TTRS_UNMAPPED) && !folio_mapped(folio)) || |
153 | ((flags & TTRS_FULL) && mem_cgroup_swap_full(folio))) |
154 | ret = folio_free_swap(folio); |
155 | folio_unlock(folio); |
156 | } |
157 | folio_put(folio); |
158 | return ret; |
159 | } |
160 | |
161 | static inline struct swap_extent *first_se(struct swap_info_struct *sis) |
162 | { |
163 | struct rb_node *rb = rb_first(&sis->swap_extent_root); |
164 | return rb_entry(rb, struct swap_extent, rb_node); |
165 | } |
166 | |
167 | static inline struct swap_extent *next_se(struct swap_extent *se) |
168 | { |
169 | struct rb_node *rb = rb_next(&se->rb_node); |
170 | return rb ? rb_entry(rb, struct swap_extent, rb_node) : NULL; |
171 | } |
172 | |
173 | /* |
174 | * swapon tell device that all the old swap contents can be discarded, |
175 | * to allow the swap device to optimize its wear-levelling. |
176 | */ |
177 | static int discard_swap(struct swap_info_struct *si) |
178 | { |
179 | struct swap_extent *se; |
180 | sector_t start_block; |
181 | sector_t nr_blocks; |
182 | int err = 0; |
183 | |
184 | /* Do not discard the swap header page! */ |
185 | se = first_se(sis: si); |
186 | start_block = (se->start_block + 1) << (PAGE_SHIFT - 9); |
187 | nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9); |
188 | if (nr_blocks) { |
189 | err = blkdev_issue_discard(bdev: si->bdev, sector: start_block, |
190 | nr_sects: nr_blocks, GFP_KERNEL); |
191 | if (err) |
192 | return err; |
193 | cond_resched(); |
194 | } |
195 | |
196 | for (se = next_se(se); se; se = next_se(se)) { |
197 | start_block = se->start_block << (PAGE_SHIFT - 9); |
198 | nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); |
199 | |
200 | err = blkdev_issue_discard(bdev: si->bdev, sector: start_block, |
201 | nr_sects: nr_blocks, GFP_KERNEL); |
202 | if (err) |
203 | break; |
204 | |
205 | cond_resched(); |
206 | } |
207 | return err; /* That will often be -EOPNOTSUPP */ |
208 | } |
209 | |
210 | static struct swap_extent * |
211 | offset_to_swap_extent(struct swap_info_struct *sis, unsigned long offset) |
212 | { |
213 | struct swap_extent *se; |
214 | struct rb_node *rb; |
215 | |
216 | rb = sis->swap_extent_root.rb_node; |
217 | while (rb) { |
218 | se = rb_entry(rb, struct swap_extent, rb_node); |
219 | if (offset < se->start_page) |
220 | rb = rb->rb_left; |
221 | else if (offset >= se->start_page + se->nr_pages) |
222 | rb = rb->rb_right; |
223 | else |
224 | return se; |
225 | } |
226 | /* It *must* be present */ |
227 | BUG(); |
228 | } |
229 | |
230 | sector_t swap_page_sector(struct page *page) |
231 | { |
232 | struct swap_info_struct *sis = page_swap_info(page); |
233 | struct swap_extent *se; |
234 | sector_t sector; |
235 | pgoff_t offset; |
236 | |
237 | offset = __page_file_index(page); |
238 | se = offset_to_swap_extent(sis, offset); |
239 | sector = se->start_block + (offset - se->start_page); |
240 | return sector << (PAGE_SHIFT - 9); |
241 | } |
242 | |
243 | /* |
244 | * swap allocation tell device that a cluster of swap can now be discarded, |
245 | * to allow the swap device to optimize its wear-levelling. |
246 | */ |
247 | static void discard_swap_cluster(struct swap_info_struct *si, |
248 | pgoff_t start_page, pgoff_t nr_pages) |
249 | { |
250 | struct swap_extent *se = offset_to_swap_extent(sis: si, offset: start_page); |
251 | |
252 | while (nr_pages) { |
253 | pgoff_t offset = start_page - se->start_page; |
254 | sector_t start_block = se->start_block + offset; |
255 | sector_t nr_blocks = se->nr_pages - offset; |
256 | |
257 | if (nr_blocks > nr_pages) |
258 | nr_blocks = nr_pages; |
259 | start_page += nr_blocks; |
260 | nr_pages -= nr_blocks; |
261 | |
262 | start_block <<= PAGE_SHIFT - 9; |
263 | nr_blocks <<= PAGE_SHIFT - 9; |
264 | if (blkdev_issue_discard(bdev: si->bdev, sector: start_block, |
265 | nr_sects: nr_blocks, GFP_NOIO)) |
266 | break; |
267 | |
268 | se = next_se(se); |
269 | } |
270 | } |
271 | |
272 | #ifdef CONFIG_THP_SWAP |
273 | #define SWAPFILE_CLUSTER HPAGE_PMD_NR |
274 | |
275 | #define swap_entry_size(size) (size) |
276 | #else |
277 | #define SWAPFILE_CLUSTER 256 |
278 | |
279 | /* |
280 | * Define swap_entry_size() as constant to let compiler to optimize |
281 | * out some code if !CONFIG_THP_SWAP |
282 | */ |
283 | #define swap_entry_size(size) 1 |
284 | #endif |
285 | #define LATENCY_LIMIT 256 |
286 | |
287 | static inline void cluster_set_flag(struct swap_cluster_info *info, |
288 | unsigned int flag) |
289 | { |
290 | info->flags = flag; |
291 | } |
292 | |
293 | static inline unsigned int cluster_count(struct swap_cluster_info *info) |
294 | { |
295 | return info->data; |
296 | } |
297 | |
298 | static inline void cluster_set_count(struct swap_cluster_info *info, |
299 | unsigned int c) |
300 | { |
301 | info->data = c; |
302 | } |
303 | |
304 | static inline void cluster_set_count_flag(struct swap_cluster_info *info, |
305 | unsigned int c, unsigned int f) |
306 | { |
307 | info->flags = f; |
308 | info->data = c; |
309 | } |
310 | |
311 | static inline unsigned int cluster_next(struct swap_cluster_info *info) |
312 | { |
313 | return info->data; |
314 | } |
315 | |
316 | static inline void cluster_set_next(struct swap_cluster_info *info, |
317 | unsigned int n) |
318 | { |
319 | info->data = n; |
320 | } |
321 | |
322 | static inline void cluster_set_next_flag(struct swap_cluster_info *info, |
323 | unsigned int n, unsigned int f) |
324 | { |
325 | info->flags = f; |
326 | info->data = n; |
327 | } |
328 | |
329 | static inline bool cluster_is_free(struct swap_cluster_info *info) |
330 | { |
331 | return info->flags & CLUSTER_FLAG_FREE; |
332 | } |
333 | |
334 | static inline bool cluster_is_null(struct swap_cluster_info *info) |
335 | { |
336 | return info->flags & CLUSTER_FLAG_NEXT_NULL; |
337 | } |
338 | |
339 | static inline void cluster_set_null(struct swap_cluster_info *info) |
340 | { |
341 | info->flags = CLUSTER_FLAG_NEXT_NULL; |
342 | info->data = 0; |
343 | } |
344 | |
345 | static inline bool cluster_is_huge(struct swap_cluster_info *info) |
346 | { |
347 | if (IS_ENABLED(CONFIG_THP_SWAP)) |
348 | return info->flags & CLUSTER_FLAG_HUGE; |
349 | return false; |
350 | } |
351 | |
352 | static inline void cluster_clear_huge(struct swap_cluster_info *info) |
353 | { |
354 | info->flags &= ~CLUSTER_FLAG_HUGE; |
355 | } |
356 | |
357 | static inline struct swap_cluster_info *lock_cluster(struct swap_info_struct *si, |
358 | unsigned long offset) |
359 | { |
360 | struct swap_cluster_info *ci; |
361 | |
362 | ci = si->cluster_info; |
363 | if (ci) { |
364 | ci += offset / SWAPFILE_CLUSTER; |
365 | spin_lock(lock: &ci->lock); |
366 | } |
367 | return ci; |
368 | } |
369 | |
370 | static inline void unlock_cluster(struct swap_cluster_info *ci) |
371 | { |
372 | if (ci) |
373 | spin_unlock(lock: &ci->lock); |
374 | } |
375 | |
376 | /* |
377 | * Determine the locking method in use for this device. Return |
378 | * swap_cluster_info if SSD-style cluster-based locking is in place. |
379 | */ |
380 | static inline struct swap_cluster_info *lock_cluster_or_swap_info( |
381 | struct swap_info_struct *si, unsigned long offset) |
382 | { |
383 | struct swap_cluster_info *ci; |
384 | |
385 | /* Try to use fine-grained SSD-style locking if available: */ |
386 | ci = lock_cluster(si, offset); |
387 | /* Otherwise, fall back to traditional, coarse locking: */ |
388 | if (!ci) |
389 | spin_lock(lock: &si->lock); |
390 | |
391 | return ci; |
392 | } |
393 | |
394 | static inline void unlock_cluster_or_swap_info(struct swap_info_struct *si, |
395 | struct swap_cluster_info *ci) |
396 | { |
397 | if (ci) |
398 | unlock_cluster(ci); |
399 | else |
400 | spin_unlock(lock: &si->lock); |
401 | } |
402 | |
403 | static inline bool cluster_list_empty(struct swap_cluster_list *list) |
404 | { |
405 | return cluster_is_null(info: &list->head); |
406 | } |
407 | |
408 | static inline unsigned int cluster_list_first(struct swap_cluster_list *list) |
409 | { |
410 | return cluster_next(info: &list->head); |
411 | } |
412 | |
413 | static void cluster_list_init(struct swap_cluster_list *list) |
414 | { |
415 | cluster_set_null(info: &list->head); |
416 | cluster_set_null(info: &list->tail); |
417 | } |
418 | |
419 | static void cluster_list_add_tail(struct swap_cluster_list *list, |
420 | struct swap_cluster_info *ci, |
421 | unsigned int idx) |
422 | { |
423 | if (cluster_list_empty(list)) { |
424 | cluster_set_next_flag(info: &list->head, n: idx, f: 0); |
425 | cluster_set_next_flag(info: &list->tail, n: idx, f: 0); |
426 | } else { |
427 | struct swap_cluster_info *ci_tail; |
428 | unsigned int tail = cluster_next(info: &list->tail); |
429 | |
430 | /* |
431 | * Nested cluster lock, but both cluster locks are |
432 | * only acquired when we held swap_info_struct->lock |
433 | */ |
434 | ci_tail = ci + tail; |
435 | spin_lock_nested(&ci_tail->lock, SINGLE_DEPTH_NESTING); |
436 | cluster_set_next(info: ci_tail, n: idx); |
437 | spin_unlock(lock: &ci_tail->lock); |
438 | cluster_set_next_flag(info: &list->tail, n: idx, f: 0); |
439 | } |
440 | } |
441 | |
442 | static unsigned int cluster_list_del_first(struct swap_cluster_list *list, |
443 | struct swap_cluster_info *ci) |
444 | { |
445 | unsigned int idx; |
446 | |
447 | idx = cluster_next(info: &list->head); |
448 | if (cluster_next(info: &list->tail) == idx) { |
449 | cluster_set_null(info: &list->head); |
450 | cluster_set_null(info: &list->tail); |
451 | } else |
452 | cluster_set_next_flag(info: &list->head, |
453 | n: cluster_next(info: &ci[idx]), f: 0); |
454 | |
455 | return idx; |
456 | } |
457 | |
458 | /* Add a cluster to discard list and schedule it to do discard */ |
459 | static void swap_cluster_schedule_discard(struct swap_info_struct *si, |
460 | unsigned int idx) |
461 | { |
462 | /* |
463 | * If scan_swap_map_slots() can't find a free cluster, it will check |
464 | * si->swap_map directly. To make sure the discarding cluster isn't |
465 | * taken by scan_swap_map_slots(), mark the swap entries bad (occupied). |
466 | * It will be cleared after discard |
467 | */ |
468 | memset(si->swap_map + idx * SWAPFILE_CLUSTER, |
469 | SWAP_MAP_BAD, SWAPFILE_CLUSTER); |
470 | |
471 | cluster_list_add_tail(list: &si->discard_clusters, ci: si->cluster_info, idx); |
472 | |
473 | schedule_work(work: &si->discard_work); |
474 | } |
475 | |
476 | static void __free_cluster(struct swap_info_struct *si, unsigned long idx) |
477 | { |
478 | struct swap_cluster_info *ci = si->cluster_info; |
479 | |
480 | cluster_set_flag(info: ci + idx, CLUSTER_FLAG_FREE); |
481 | cluster_list_add_tail(list: &si->free_clusters, ci, idx); |
482 | } |
483 | |
484 | /* |
485 | * Doing discard actually. After a cluster discard is finished, the cluster |
486 | * will be added to free cluster list. caller should hold si->lock. |
487 | */ |
488 | static void swap_do_scheduled_discard(struct swap_info_struct *si) |
489 | { |
490 | struct swap_cluster_info *info, *ci; |
491 | unsigned int idx; |
492 | |
493 | info = si->cluster_info; |
494 | |
495 | while (!cluster_list_empty(list: &si->discard_clusters)) { |
496 | idx = cluster_list_del_first(list: &si->discard_clusters, ci: info); |
497 | spin_unlock(lock: &si->lock); |
498 | |
499 | discard_swap_cluster(si, start_page: idx * SWAPFILE_CLUSTER, |
500 | SWAPFILE_CLUSTER); |
501 | |
502 | spin_lock(lock: &si->lock); |
503 | ci = lock_cluster(si, offset: idx * SWAPFILE_CLUSTER); |
504 | __free_cluster(si, idx); |
505 | memset(si->swap_map + idx * SWAPFILE_CLUSTER, |
506 | 0, SWAPFILE_CLUSTER); |
507 | unlock_cluster(ci); |
508 | } |
509 | } |
510 | |
511 | static void swap_discard_work(struct work_struct *work) |
512 | { |
513 | struct swap_info_struct *si; |
514 | |
515 | si = container_of(work, struct swap_info_struct, discard_work); |
516 | |
517 | spin_lock(lock: &si->lock); |
518 | swap_do_scheduled_discard(si); |
519 | spin_unlock(lock: &si->lock); |
520 | } |
521 | |
522 | static void swap_users_ref_free(struct percpu_ref *ref) |
523 | { |
524 | struct swap_info_struct *si; |
525 | |
526 | si = container_of(ref, struct swap_info_struct, users); |
527 | complete(&si->comp); |
528 | } |
529 | |
530 | static void alloc_cluster(struct swap_info_struct *si, unsigned long idx) |
531 | { |
532 | struct swap_cluster_info *ci = si->cluster_info; |
533 | |
534 | VM_BUG_ON(cluster_list_first(&si->free_clusters) != idx); |
535 | cluster_list_del_first(list: &si->free_clusters, ci); |
536 | cluster_set_count_flag(info: ci + idx, c: 0, f: 0); |
537 | } |
538 | |
539 | static void free_cluster(struct swap_info_struct *si, unsigned long idx) |
540 | { |
541 | struct swap_cluster_info *ci = si->cluster_info + idx; |
542 | |
543 | VM_BUG_ON(cluster_count(ci) != 0); |
544 | /* |
545 | * If the swap is discardable, prepare discard the cluster |
546 | * instead of free it immediately. The cluster will be freed |
547 | * after discard. |
548 | */ |
549 | if ((si->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) == |
550 | (SWP_WRITEOK | SWP_PAGE_DISCARD)) { |
551 | swap_cluster_schedule_discard(si, idx); |
552 | return; |
553 | } |
554 | |
555 | __free_cluster(si, idx); |
556 | } |
557 | |
558 | /* |
559 | * The cluster corresponding to page_nr will be used. The cluster will be |
560 | * removed from free cluster list and its usage counter will be increased. |
561 | */ |
562 | static void inc_cluster_info_page(struct swap_info_struct *p, |
563 | struct swap_cluster_info *cluster_info, unsigned long page_nr) |
564 | { |
565 | unsigned long idx = page_nr / SWAPFILE_CLUSTER; |
566 | |
567 | if (!cluster_info) |
568 | return; |
569 | if (cluster_is_free(info: &cluster_info[idx])) |
570 | alloc_cluster(si: p, idx); |
571 | |
572 | VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER); |
573 | cluster_set_count(info: &cluster_info[idx], |
574 | c: cluster_count(info: &cluster_info[idx]) + 1); |
575 | } |
576 | |
577 | /* |
578 | * The cluster corresponding to page_nr decreases one usage. If the usage |
579 | * counter becomes 0, which means no page in the cluster is in using, we can |
580 | * optionally discard the cluster and add it to free cluster list. |
581 | */ |
582 | static void dec_cluster_info_page(struct swap_info_struct *p, |
583 | struct swap_cluster_info *cluster_info, unsigned long page_nr) |
584 | { |
585 | unsigned long idx = page_nr / SWAPFILE_CLUSTER; |
586 | |
587 | if (!cluster_info) |
588 | return; |
589 | |
590 | VM_BUG_ON(cluster_count(&cluster_info[idx]) == 0); |
591 | cluster_set_count(info: &cluster_info[idx], |
592 | c: cluster_count(info: &cluster_info[idx]) - 1); |
593 | |
594 | if (cluster_count(info: &cluster_info[idx]) == 0) |
595 | free_cluster(si: p, idx); |
596 | } |
597 | |
598 | /* |
599 | * It's possible scan_swap_map_slots() uses a free cluster in the middle of free |
600 | * cluster list. Avoiding such abuse to avoid list corruption. |
601 | */ |
602 | static bool |
603 | scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si, |
604 | unsigned long offset) |
605 | { |
606 | struct percpu_cluster *percpu_cluster; |
607 | bool conflict; |
608 | |
609 | offset /= SWAPFILE_CLUSTER; |
610 | conflict = !cluster_list_empty(list: &si->free_clusters) && |
611 | offset != cluster_list_first(list: &si->free_clusters) && |
612 | cluster_is_free(info: &si->cluster_info[offset]); |
613 | |
614 | if (!conflict) |
615 | return false; |
616 | |
617 | percpu_cluster = this_cpu_ptr(si->percpu_cluster); |
618 | cluster_set_null(info: &percpu_cluster->index); |
619 | return true; |
620 | } |
621 | |
622 | /* |
623 | * Try to get a swap entry from current cpu's swap entry pool (a cluster). This |
624 | * might involve allocating a new cluster for current CPU too. |
625 | */ |
626 | static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si, |
627 | unsigned long *offset, unsigned long *scan_base) |
628 | { |
629 | struct percpu_cluster *cluster; |
630 | struct swap_cluster_info *ci; |
631 | unsigned long tmp, max; |
632 | |
633 | new_cluster: |
634 | cluster = this_cpu_ptr(si->percpu_cluster); |
635 | if (cluster_is_null(info: &cluster->index)) { |
636 | if (!cluster_list_empty(list: &si->free_clusters)) { |
637 | cluster->index = si->free_clusters.head; |
638 | cluster->next = cluster_next(info: &cluster->index) * |
639 | SWAPFILE_CLUSTER; |
640 | } else if (!cluster_list_empty(list: &si->discard_clusters)) { |
641 | /* |
642 | * we don't have free cluster but have some clusters in |
643 | * discarding, do discard now and reclaim them, then |
644 | * reread cluster_next_cpu since we dropped si->lock |
645 | */ |
646 | swap_do_scheduled_discard(si); |
647 | *scan_base = this_cpu_read(*si->cluster_next_cpu); |
648 | *offset = *scan_base; |
649 | goto new_cluster; |
650 | } else |
651 | return false; |
652 | } |
653 | |
654 | /* |
655 | * Other CPUs can use our cluster if they can't find a free cluster, |
656 | * check if there is still free entry in the cluster |
657 | */ |
658 | tmp = cluster->next; |
659 | max = min_t(unsigned long, si->max, |
660 | (cluster_next(&cluster->index) + 1) * SWAPFILE_CLUSTER); |
661 | if (tmp < max) { |
662 | ci = lock_cluster(si, offset: tmp); |
663 | while (tmp < max) { |
664 | if (!si->swap_map[tmp]) |
665 | break; |
666 | tmp++; |
667 | } |
668 | unlock_cluster(ci); |
669 | } |
670 | if (tmp >= max) { |
671 | cluster_set_null(info: &cluster->index); |
672 | goto new_cluster; |
673 | } |
674 | cluster->next = tmp + 1; |
675 | *offset = tmp; |
676 | *scan_base = tmp; |
677 | return true; |
678 | } |
679 | |
680 | static void __del_from_avail_list(struct swap_info_struct *p) |
681 | { |
682 | int nid; |
683 | |
684 | assert_spin_locked(&p->lock); |
685 | for_each_node(nid) |
686 | plist_del(node: &p->avail_lists[nid], head: &swap_avail_heads[nid]); |
687 | } |
688 | |
689 | static void del_from_avail_list(struct swap_info_struct *p) |
690 | { |
691 | spin_lock(lock: &swap_avail_lock); |
692 | __del_from_avail_list(p); |
693 | spin_unlock(lock: &swap_avail_lock); |
694 | } |
695 | |
696 | static void swap_range_alloc(struct swap_info_struct *si, unsigned long offset, |
697 | unsigned int nr_entries) |
698 | { |
699 | unsigned int end = offset + nr_entries - 1; |
700 | |
701 | if (offset == si->lowest_bit) |
702 | si->lowest_bit += nr_entries; |
703 | if (end == si->highest_bit) |
704 | WRITE_ONCE(si->highest_bit, si->highest_bit - nr_entries); |
705 | WRITE_ONCE(si->inuse_pages, si->inuse_pages + nr_entries); |
706 | if (si->inuse_pages == si->pages) { |
707 | si->lowest_bit = si->max; |
708 | si->highest_bit = 0; |
709 | del_from_avail_list(p: si); |
710 | } |
711 | } |
712 | |
713 | static void add_to_avail_list(struct swap_info_struct *p) |
714 | { |
715 | int nid; |
716 | |
717 | spin_lock(lock: &swap_avail_lock); |
718 | for_each_node(nid) |
719 | plist_add(node: &p->avail_lists[nid], head: &swap_avail_heads[nid]); |
720 | spin_unlock(lock: &swap_avail_lock); |
721 | } |
722 | |
723 | static void swap_range_free(struct swap_info_struct *si, unsigned long offset, |
724 | unsigned int nr_entries) |
725 | { |
726 | unsigned long begin = offset; |
727 | unsigned long end = offset + nr_entries - 1; |
728 | void (*swap_slot_free_notify)(struct block_device *, unsigned long); |
729 | |
730 | if (offset < si->lowest_bit) |
731 | si->lowest_bit = offset; |
732 | if (end > si->highest_bit) { |
733 | bool was_full = !si->highest_bit; |
734 | |
735 | WRITE_ONCE(si->highest_bit, end); |
736 | if (was_full && (si->flags & SWP_WRITEOK)) |
737 | add_to_avail_list(p: si); |
738 | } |
739 | atomic_long_add(i: nr_entries, v: &nr_swap_pages); |
740 | WRITE_ONCE(si->inuse_pages, si->inuse_pages - nr_entries); |
741 | if (si->flags & SWP_BLKDEV) |
742 | swap_slot_free_notify = |
743 | si->bdev->bd_disk->fops->swap_slot_free_notify; |
744 | else |
745 | swap_slot_free_notify = NULL; |
746 | while (offset <= end) { |
747 | arch_swap_invalidate_page(type: si->type, offset); |
748 | zswap_invalidate(type: si->type, offset); |
749 | if (swap_slot_free_notify) |
750 | swap_slot_free_notify(si->bdev, offset); |
751 | offset++; |
752 | } |
753 | clear_shadow_from_swap_cache(type: si->type, begin, end); |
754 | } |
755 | |
756 | static void set_cluster_next(struct swap_info_struct *si, unsigned long next) |
757 | { |
758 | unsigned long prev; |
759 | |
760 | if (!(si->flags & SWP_SOLIDSTATE)) { |
761 | si->cluster_next = next; |
762 | return; |
763 | } |
764 | |
765 | prev = this_cpu_read(*si->cluster_next_cpu); |
766 | /* |
767 | * Cross the swap address space size aligned trunk, choose |
768 | * another trunk randomly to avoid lock contention on swap |
769 | * address space if possible. |
770 | */ |
771 | if ((prev >> SWAP_ADDRESS_SPACE_SHIFT) != |
772 | (next >> SWAP_ADDRESS_SPACE_SHIFT)) { |
773 | /* No free swap slots available */ |
774 | if (si->highest_bit <= si->lowest_bit) |
775 | return; |
776 | next = get_random_u32_inclusive(floor: si->lowest_bit, ceil: si->highest_bit); |
777 | next = ALIGN_DOWN(next, SWAP_ADDRESS_SPACE_PAGES); |
778 | next = max_t(unsigned int, next, si->lowest_bit); |
779 | } |
780 | this_cpu_write(*si->cluster_next_cpu, next); |
781 | } |
782 | |
783 | static bool swap_offset_available_and_locked(struct swap_info_struct *si, |
784 | unsigned long offset) |
785 | { |
786 | if (data_race(!si->swap_map[offset])) { |
787 | spin_lock(lock: &si->lock); |
788 | return true; |
789 | } |
790 | |
791 | if (vm_swap_full() && READ_ONCE(si->swap_map[offset]) == SWAP_HAS_CACHE) { |
792 | spin_lock(lock: &si->lock); |
793 | return true; |
794 | } |
795 | |
796 | return false; |
797 | } |
798 | |
799 | static int scan_swap_map_slots(struct swap_info_struct *si, |
800 | unsigned char usage, int nr, |
801 | swp_entry_t slots[]) |
802 | { |
803 | struct swap_cluster_info *ci; |
804 | unsigned long offset; |
805 | unsigned long scan_base; |
806 | unsigned long last_in_cluster = 0; |
807 | int latency_ration = LATENCY_LIMIT; |
808 | int n_ret = 0; |
809 | bool scanned_many = false; |
810 | |
811 | /* |
812 | * We try to cluster swap pages by allocating them sequentially |
813 | * in swap. Once we've allocated SWAPFILE_CLUSTER pages this |
814 | * way, however, we resort to first-free allocation, starting |
815 | * a new cluster. This prevents us from scattering swap pages |
816 | * all over the entire swap partition, so that we reduce |
817 | * overall disk seek times between swap pages. -- sct |
818 | * But we do now try to find an empty cluster. -Andrea |
819 | * And we let swap pages go all over an SSD partition. Hugh |
820 | */ |
821 | |
822 | si->flags += SWP_SCANNING; |
823 | /* |
824 | * Use percpu scan base for SSD to reduce lock contention on |
825 | * cluster and swap cache. For HDD, sequential access is more |
826 | * important. |
827 | */ |
828 | if (si->flags & SWP_SOLIDSTATE) |
829 | scan_base = this_cpu_read(*si->cluster_next_cpu); |
830 | else |
831 | scan_base = si->cluster_next; |
832 | offset = scan_base; |
833 | |
834 | /* SSD algorithm */ |
835 | if (si->cluster_info) { |
836 | if (!scan_swap_map_try_ssd_cluster(si, offset: &offset, scan_base: &scan_base)) |
837 | goto scan; |
838 | } else if (unlikely(!si->cluster_nr--)) { |
839 | if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { |
840 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
841 | goto checks; |
842 | } |
843 | |
844 | spin_unlock(lock: &si->lock); |
845 | |
846 | /* |
847 | * If seek is expensive, start searching for new cluster from |
848 | * start of partition, to minimize the span of allocated swap. |
849 | * If seek is cheap, that is the SWP_SOLIDSTATE si->cluster_info |
850 | * case, just handled by scan_swap_map_try_ssd_cluster() above. |
851 | */ |
852 | scan_base = offset = si->lowest_bit; |
853 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
854 | |
855 | /* Locate the first empty (unaligned) cluster */ |
856 | for (; last_in_cluster <= si->highest_bit; offset++) { |
857 | if (si->swap_map[offset]) |
858 | last_in_cluster = offset + SWAPFILE_CLUSTER; |
859 | else if (offset == last_in_cluster) { |
860 | spin_lock(lock: &si->lock); |
861 | offset -= SWAPFILE_CLUSTER - 1; |
862 | si->cluster_next = offset; |
863 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
864 | goto checks; |
865 | } |
866 | if (unlikely(--latency_ration < 0)) { |
867 | cond_resched(); |
868 | latency_ration = LATENCY_LIMIT; |
869 | } |
870 | } |
871 | |
872 | offset = scan_base; |
873 | spin_lock(lock: &si->lock); |
874 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
875 | } |
876 | |
877 | checks: |
878 | if (si->cluster_info) { |
879 | while (scan_swap_map_ssd_cluster_conflict(si, offset)) { |
880 | /* take a break if we already got some slots */ |
881 | if (n_ret) |
882 | goto done; |
883 | if (!scan_swap_map_try_ssd_cluster(si, offset: &offset, |
884 | scan_base: &scan_base)) |
885 | goto scan; |
886 | } |
887 | } |
888 | if (!(si->flags & SWP_WRITEOK)) |
889 | goto no_page; |
890 | if (!si->highest_bit) |
891 | goto no_page; |
892 | if (offset > si->highest_bit) |
893 | scan_base = offset = si->lowest_bit; |
894 | |
895 | ci = lock_cluster(si, offset); |
896 | /* reuse swap entry of cache-only swap if not busy. */ |
897 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
898 | int swap_was_freed; |
899 | unlock_cluster(ci); |
900 | spin_unlock(lock: &si->lock); |
901 | swap_was_freed = __try_to_reclaim_swap(si, offset, TTRS_ANYWAY); |
902 | spin_lock(lock: &si->lock); |
903 | /* entry was freed successfully, try to use this again */ |
904 | if (swap_was_freed) |
905 | goto checks; |
906 | goto scan; /* check next one */ |
907 | } |
908 | |
909 | if (si->swap_map[offset]) { |
910 | unlock_cluster(ci); |
911 | if (!n_ret) |
912 | goto scan; |
913 | else |
914 | goto done; |
915 | } |
916 | WRITE_ONCE(si->swap_map[offset], usage); |
917 | inc_cluster_info_page(p: si, cluster_info: si->cluster_info, page_nr: offset); |
918 | unlock_cluster(ci); |
919 | |
920 | swap_range_alloc(si, offset, nr_entries: 1); |
921 | slots[n_ret++] = swp_entry(type: si->type, offset); |
922 | |
923 | /* got enough slots or reach max slots? */ |
924 | if ((n_ret == nr) || (offset >= si->highest_bit)) |
925 | goto done; |
926 | |
927 | /* search for next available slot */ |
928 | |
929 | /* time to take a break? */ |
930 | if (unlikely(--latency_ration < 0)) { |
931 | if (n_ret) |
932 | goto done; |
933 | spin_unlock(lock: &si->lock); |
934 | cond_resched(); |
935 | spin_lock(lock: &si->lock); |
936 | latency_ration = LATENCY_LIMIT; |
937 | } |
938 | |
939 | /* try to get more slots in cluster */ |
940 | if (si->cluster_info) { |
941 | if (scan_swap_map_try_ssd_cluster(si, offset: &offset, scan_base: &scan_base)) |
942 | goto checks; |
943 | } else if (si->cluster_nr && !si->swap_map[++offset]) { |
944 | /* non-ssd case, still more slots in cluster? */ |
945 | --si->cluster_nr; |
946 | goto checks; |
947 | } |
948 | |
949 | /* |
950 | * Even if there's no free clusters available (fragmented), |
951 | * try to scan a little more quickly with lock held unless we |
952 | * have scanned too many slots already. |
953 | */ |
954 | if (!scanned_many) { |
955 | unsigned long scan_limit; |
956 | |
957 | if (offset < scan_base) |
958 | scan_limit = scan_base; |
959 | else |
960 | scan_limit = si->highest_bit; |
961 | for (; offset <= scan_limit && --latency_ration > 0; |
962 | offset++) { |
963 | if (!si->swap_map[offset]) |
964 | goto checks; |
965 | } |
966 | } |
967 | |
968 | done: |
969 | set_cluster_next(si, next: offset + 1); |
970 | si->flags -= SWP_SCANNING; |
971 | return n_ret; |
972 | |
973 | scan: |
974 | spin_unlock(lock: &si->lock); |
975 | while (++offset <= READ_ONCE(si->highest_bit)) { |
976 | if (unlikely(--latency_ration < 0)) { |
977 | cond_resched(); |
978 | latency_ration = LATENCY_LIMIT; |
979 | scanned_many = true; |
980 | } |
981 | if (swap_offset_available_and_locked(si, offset)) |
982 | goto checks; |
983 | } |
984 | offset = si->lowest_bit; |
985 | while (offset < scan_base) { |
986 | if (unlikely(--latency_ration < 0)) { |
987 | cond_resched(); |
988 | latency_ration = LATENCY_LIMIT; |
989 | scanned_many = true; |
990 | } |
991 | if (swap_offset_available_and_locked(si, offset)) |
992 | goto checks; |
993 | offset++; |
994 | } |
995 | spin_lock(lock: &si->lock); |
996 | |
997 | no_page: |
998 | si->flags -= SWP_SCANNING; |
999 | return n_ret; |
1000 | } |
1001 | |
1002 | static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) |
1003 | { |
1004 | unsigned long idx; |
1005 | struct swap_cluster_info *ci; |
1006 | unsigned long offset; |
1007 | |
1008 | /* |
1009 | * Should not even be attempting cluster allocations when huge |
1010 | * page swap is disabled. Warn and fail the allocation. |
1011 | */ |
1012 | if (!IS_ENABLED(CONFIG_THP_SWAP)) { |
1013 | VM_WARN_ON_ONCE(1); |
1014 | return 0; |
1015 | } |
1016 | |
1017 | if (cluster_list_empty(list: &si->free_clusters)) |
1018 | return 0; |
1019 | |
1020 | idx = cluster_list_first(list: &si->free_clusters); |
1021 | offset = idx * SWAPFILE_CLUSTER; |
1022 | ci = lock_cluster(si, offset); |
1023 | alloc_cluster(si, idx); |
1024 | cluster_set_count_flag(info: ci, SWAPFILE_CLUSTER, CLUSTER_FLAG_HUGE); |
1025 | |
1026 | memset(si->swap_map + offset, SWAP_HAS_CACHE, SWAPFILE_CLUSTER); |
1027 | unlock_cluster(ci); |
1028 | swap_range_alloc(si, offset, SWAPFILE_CLUSTER); |
1029 | *slot = swp_entry(type: si->type, offset); |
1030 | |
1031 | return 1; |
1032 | } |
1033 | |
1034 | static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx) |
1035 | { |
1036 | unsigned long offset = idx * SWAPFILE_CLUSTER; |
1037 | struct swap_cluster_info *ci; |
1038 | |
1039 | ci = lock_cluster(si, offset); |
1040 | memset(si->swap_map + offset, 0, SWAPFILE_CLUSTER); |
1041 | cluster_set_count_flag(info: ci, c: 0, f: 0); |
1042 | free_cluster(si, idx); |
1043 | unlock_cluster(ci); |
1044 | swap_range_free(si, offset, SWAPFILE_CLUSTER); |
1045 | } |
1046 | |
1047 | int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size) |
1048 | { |
1049 | unsigned long size = swap_entry_size(entry_size); |
1050 | struct swap_info_struct *si, *next; |
1051 | long avail_pgs; |
1052 | int n_ret = 0; |
1053 | int node; |
1054 | |
1055 | /* Only single cluster request supported */ |
1056 | WARN_ON_ONCE(n_goal > 1 && size == SWAPFILE_CLUSTER); |
1057 | |
1058 | spin_lock(lock: &swap_avail_lock); |
1059 | |
1060 | avail_pgs = atomic_long_read(v: &nr_swap_pages) / size; |
1061 | if (avail_pgs <= 0) { |
1062 | spin_unlock(lock: &swap_avail_lock); |
1063 | goto noswap; |
1064 | } |
1065 | |
1066 | n_goal = min3((long)n_goal, (long)SWAP_BATCH, avail_pgs); |
1067 | |
1068 | atomic_long_sub(i: n_goal * size, v: &nr_swap_pages); |
1069 | |
1070 | start_over: |
1071 | node = numa_node_id(); |
1072 | plist_for_each_entry_safe(si, next, &swap_avail_heads[node], avail_lists[node]) { |
1073 | /* requeue si to after same-priority siblings */ |
1074 | plist_requeue(node: &si->avail_lists[node], head: &swap_avail_heads[node]); |
1075 | spin_unlock(lock: &swap_avail_lock); |
1076 | spin_lock(lock: &si->lock); |
1077 | if (!si->highest_bit || !(si->flags & SWP_WRITEOK)) { |
1078 | spin_lock(lock: &swap_avail_lock); |
1079 | if (plist_node_empty(node: &si->avail_lists[node])) { |
1080 | spin_unlock(lock: &si->lock); |
1081 | goto nextsi; |
1082 | } |
1083 | WARN(!si->highest_bit, |
1084 | "swap_info %d in list but !highest_bit\n" , |
1085 | si->type); |
1086 | WARN(!(si->flags & SWP_WRITEOK), |
1087 | "swap_info %d in list but !SWP_WRITEOK\n" , |
1088 | si->type); |
1089 | __del_from_avail_list(p: si); |
1090 | spin_unlock(lock: &si->lock); |
1091 | goto nextsi; |
1092 | } |
1093 | if (size == SWAPFILE_CLUSTER) { |
1094 | if (si->flags & SWP_BLKDEV) |
1095 | n_ret = swap_alloc_cluster(si, slot: swp_entries); |
1096 | } else |
1097 | n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, |
1098 | nr: n_goal, slots: swp_entries); |
1099 | spin_unlock(lock: &si->lock); |
1100 | if (n_ret || size == SWAPFILE_CLUSTER) |
1101 | goto check_out; |
1102 | cond_resched(); |
1103 | |
1104 | spin_lock(lock: &swap_avail_lock); |
1105 | nextsi: |
1106 | /* |
1107 | * if we got here, it's likely that si was almost full before, |
1108 | * and since scan_swap_map_slots() can drop the si->lock, |
1109 | * multiple callers probably all tried to get a page from the |
1110 | * same si and it filled up before we could get one; or, the si |
1111 | * filled up between us dropping swap_avail_lock and taking |
1112 | * si->lock. Since we dropped the swap_avail_lock, the |
1113 | * swap_avail_head list may have been modified; so if next is |
1114 | * still in the swap_avail_head list then try it, otherwise |
1115 | * start over if we have not gotten any slots. |
1116 | */ |
1117 | if (plist_node_empty(node: &next->avail_lists[node])) |
1118 | goto start_over; |
1119 | } |
1120 | |
1121 | spin_unlock(lock: &swap_avail_lock); |
1122 | |
1123 | check_out: |
1124 | if (n_ret < n_goal) |
1125 | atomic_long_add(i: (long)(n_goal - n_ret) * size, |
1126 | v: &nr_swap_pages); |
1127 | noswap: |
1128 | return n_ret; |
1129 | } |
1130 | |
1131 | static struct swap_info_struct *_swap_info_get(swp_entry_t entry) |
1132 | { |
1133 | struct swap_info_struct *p; |
1134 | unsigned long offset; |
1135 | |
1136 | if (!entry.val) |
1137 | goto out; |
1138 | p = swp_swap_info(entry); |
1139 | if (!p) |
1140 | goto bad_nofile; |
1141 | if (data_race(!(p->flags & SWP_USED))) |
1142 | goto bad_device; |
1143 | offset = swp_offset(entry); |
1144 | if (offset >= p->max) |
1145 | goto bad_offset; |
1146 | if (data_race(!p->swap_map[swp_offset(entry)])) |
1147 | goto bad_free; |
1148 | return p; |
1149 | |
1150 | bad_free: |
1151 | pr_err("%s: %s%08lx\n" , __func__, Unused_offset, entry.val); |
1152 | goto out; |
1153 | bad_offset: |
1154 | pr_err("%s: %s%08lx\n" , __func__, Bad_offset, entry.val); |
1155 | goto out; |
1156 | bad_device: |
1157 | pr_err("%s: %s%08lx\n" , __func__, Unused_file, entry.val); |
1158 | goto out; |
1159 | bad_nofile: |
1160 | pr_err("%s: %s%08lx\n" , __func__, Bad_file, entry.val); |
1161 | out: |
1162 | return NULL; |
1163 | } |
1164 | |
1165 | static struct swap_info_struct *swap_info_get_cont(swp_entry_t entry, |
1166 | struct swap_info_struct *q) |
1167 | { |
1168 | struct swap_info_struct *p; |
1169 | |
1170 | p = _swap_info_get(entry); |
1171 | |
1172 | if (p != q) { |
1173 | if (q != NULL) |
1174 | spin_unlock(lock: &q->lock); |
1175 | if (p != NULL) |
1176 | spin_lock(lock: &p->lock); |
1177 | } |
1178 | return p; |
1179 | } |
1180 | |
1181 | static unsigned char __swap_entry_free_locked(struct swap_info_struct *p, |
1182 | unsigned long offset, |
1183 | unsigned char usage) |
1184 | { |
1185 | unsigned char count; |
1186 | unsigned char has_cache; |
1187 | |
1188 | count = p->swap_map[offset]; |
1189 | |
1190 | has_cache = count & SWAP_HAS_CACHE; |
1191 | count &= ~SWAP_HAS_CACHE; |
1192 | |
1193 | if (usage == SWAP_HAS_CACHE) { |
1194 | VM_BUG_ON(!has_cache); |
1195 | has_cache = 0; |
1196 | } else if (count == SWAP_MAP_SHMEM) { |
1197 | /* |
1198 | * Or we could insist on shmem.c using a special |
1199 | * swap_shmem_free() and free_shmem_swap_and_cache()... |
1200 | */ |
1201 | count = 0; |
1202 | } else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) { |
1203 | if (count == COUNT_CONTINUED) { |
1204 | if (swap_count_continued(p, offset, count)) |
1205 | count = SWAP_MAP_MAX | COUNT_CONTINUED; |
1206 | else |
1207 | count = SWAP_MAP_MAX; |
1208 | } else |
1209 | count--; |
1210 | } |
1211 | |
1212 | usage = count | has_cache; |
1213 | if (usage) |
1214 | WRITE_ONCE(p->swap_map[offset], usage); |
1215 | else |
1216 | WRITE_ONCE(p->swap_map[offset], SWAP_HAS_CACHE); |
1217 | |
1218 | return usage; |
1219 | } |
1220 | |
1221 | /* |
1222 | * When we get a swap entry, if there aren't some other ways to |
1223 | * prevent swapoff, such as the folio in swap cache is locked, page |
1224 | * table lock is held, etc., the swap entry may become invalid because |
1225 | * of swapoff. Then, we need to enclose all swap related functions |
1226 | * with get_swap_device() and put_swap_device(), unless the swap |
1227 | * functions call get/put_swap_device() by themselves. |
1228 | * |
1229 | * Check whether swap entry is valid in the swap device. If so, |
1230 | * return pointer to swap_info_struct, and keep the swap entry valid |
1231 | * via preventing the swap device from being swapoff, until |
1232 | * put_swap_device() is called. Otherwise return NULL. |
1233 | * |
1234 | * Notice that swapoff or swapoff+swapon can still happen before the |
1235 | * percpu_ref_tryget_live() in get_swap_device() or after the |
1236 | * percpu_ref_put() in put_swap_device() if there isn't any other way |
1237 | * to prevent swapoff. The caller must be prepared for that. For |
1238 | * example, the following situation is possible. |
1239 | * |
1240 | * CPU1 CPU2 |
1241 | * do_swap_page() |
1242 | * ... swapoff+swapon |
1243 | * __read_swap_cache_async() |
1244 | * swapcache_prepare() |
1245 | * __swap_duplicate() |
1246 | * // check swap_map |
1247 | * // verify PTE not changed |
1248 | * |
1249 | * In __swap_duplicate(), the swap_map need to be checked before |
1250 | * changing partly because the specified swap entry may be for another |
1251 | * swap device which has been swapoff. And in do_swap_page(), after |
1252 | * the page is read from the swap device, the PTE is verified not |
1253 | * changed with the page table locked to check whether the swap device |
1254 | * has been swapoff or swapoff+swapon. |
1255 | */ |
1256 | struct swap_info_struct *get_swap_device(swp_entry_t entry) |
1257 | { |
1258 | struct swap_info_struct *si; |
1259 | unsigned long offset; |
1260 | |
1261 | if (!entry.val) |
1262 | goto out; |
1263 | si = swp_swap_info(entry); |
1264 | if (!si) |
1265 | goto bad_nofile; |
1266 | if (!percpu_ref_tryget_live(ref: &si->users)) |
1267 | goto out; |
1268 | /* |
1269 | * Guarantee the si->users are checked before accessing other |
1270 | * fields of swap_info_struct. |
1271 | * |
1272 | * Paired with the spin_unlock() after setup_swap_info() in |
1273 | * enable_swap_info(). |
1274 | */ |
1275 | smp_rmb(); |
1276 | offset = swp_offset(entry); |
1277 | if (offset >= si->max) |
1278 | goto put_out; |
1279 | |
1280 | return si; |
1281 | bad_nofile: |
1282 | pr_err("%s: %s%08lx\n" , __func__, Bad_file, entry.val); |
1283 | out: |
1284 | return NULL; |
1285 | put_out: |
1286 | pr_err("%s: %s%08lx\n" , __func__, Bad_offset, entry.val); |
1287 | percpu_ref_put(ref: &si->users); |
1288 | return NULL; |
1289 | } |
1290 | |
1291 | static unsigned char __swap_entry_free(struct swap_info_struct *p, |
1292 | swp_entry_t entry) |
1293 | { |
1294 | struct swap_cluster_info *ci; |
1295 | unsigned long offset = swp_offset(entry); |
1296 | unsigned char usage; |
1297 | |
1298 | ci = lock_cluster_or_swap_info(si: p, offset); |
1299 | usage = __swap_entry_free_locked(p, offset, usage: 1); |
1300 | unlock_cluster_or_swap_info(si: p, ci); |
1301 | if (!usage) |
1302 | free_swap_slot(entry); |
1303 | |
1304 | return usage; |
1305 | } |
1306 | |
1307 | static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry) |
1308 | { |
1309 | struct swap_cluster_info *ci; |
1310 | unsigned long offset = swp_offset(entry); |
1311 | unsigned char count; |
1312 | |
1313 | ci = lock_cluster(si: p, offset); |
1314 | count = p->swap_map[offset]; |
1315 | VM_BUG_ON(count != SWAP_HAS_CACHE); |
1316 | p->swap_map[offset] = 0; |
1317 | dec_cluster_info_page(p, cluster_info: p->cluster_info, page_nr: offset); |
1318 | unlock_cluster(ci); |
1319 | |
1320 | mem_cgroup_uncharge_swap(entry, nr_pages: 1); |
1321 | swap_range_free(si: p, offset, nr_entries: 1); |
1322 | } |
1323 | |
1324 | /* |
1325 | * Caller has made sure that the swap device corresponding to entry |
1326 | * is still around or has not been recycled. |
1327 | */ |
1328 | void swap_free(swp_entry_t entry) |
1329 | { |
1330 | struct swap_info_struct *p; |
1331 | |
1332 | p = _swap_info_get(entry); |
1333 | if (p) |
1334 | __swap_entry_free(p, entry); |
1335 | } |
1336 | |
1337 | /* |
1338 | * Called after dropping swapcache to decrease refcnt to swap entries. |
1339 | */ |
1340 | void put_swap_folio(struct folio *folio, swp_entry_t entry) |
1341 | { |
1342 | unsigned long offset = swp_offset(entry); |
1343 | unsigned long idx = offset / SWAPFILE_CLUSTER; |
1344 | struct swap_cluster_info *ci; |
1345 | struct swap_info_struct *si; |
1346 | unsigned char *map; |
1347 | unsigned int i, free_entries = 0; |
1348 | unsigned char val; |
1349 | int size = swap_entry_size(folio_nr_pages(folio)); |
1350 | |
1351 | si = _swap_info_get(entry); |
1352 | if (!si) |
1353 | return; |
1354 | |
1355 | ci = lock_cluster_or_swap_info(si, offset); |
1356 | if (size == SWAPFILE_CLUSTER) { |
1357 | VM_BUG_ON(!cluster_is_huge(ci)); |
1358 | map = si->swap_map + offset; |
1359 | for (i = 0; i < SWAPFILE_CLUSTER; i++) { |
1360 | val = map[i]; |
1361 | VM_BUG_ON(!(val & SWAP_HAS_CACHE)); |
1362 | if (val == SWAP_HAS_CACHE) |
1363 | free_entries++; |
1364 | } |
1365 | cluster_clear_huge(info: ci); |
1366 | if (free_entries == SWAPFILE_CLUSTER) { |
1367 | unlock_cluster_or_swap_info(si, ci); |
1368 | spin_lock(lock: &si->lock); |
1369 | mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER); |
1370 | swap_free_cluster(si, idx); |
1371 | spin_unlock(lock: &si->lock); |
1372 | return; |
1373 | } |
1374 | } |
1375 | for (i = 0; i < size; i++, entry.val++) { |
1376 | if (!__swap_entry_free_locked(p: si, offset: offset + i, SWAP_HAS_CACHE)) { |
1377 | unlock_cluster_or_swap_info(si, ci); |
1378 | free_swap_slot(entry); |
1379 | if (i == size - 1) |
1380 | return; |
1381 | lock_cluster_or_swap_info(si, offset); |
1382 | } |
1383 | } |
1384 | unlock_cluster_or_swap_info(si, ci); |
1385 | } |
1386 | |
1387 | #ifdef CONFIG_THP_SWAP |
1388 | int split_swap_cluster(swp_entry_t entry) |
1389 | { |
1390 | struct swap_info_struct *si; |
1391 | struct swap_cluster_info *ci; |
1392 | unsigned long offset = swp_offset(entry); |
1393 | |
1394 | si = _swap_info_get(entry); |
1395 | if (!si) |
1396 | return -EBUSY; |
1397 | ci = lock_cluster(si, offset); |
1398 | cluster_clear_huge(info: ci); |
1399 | unlock_cluster(ci); |
1400 | return 0; |
1401 | } |
1402 | #endif |
1403 | |
1404 | static int swp_entry_cmp(const void *ent1, const void *ent2) |
1405 | { |
1406 | const swp_entry_t *e1 = ent1, *e2 = ent2; |
1407 | |
1408 | return (int)swp_type(entry: *e1) - (int)swp_type(entry: *e2); |
1409 | } |
1410 | |
1411 | void swapcache_free_entries(swp_entry_t *entries, int n) |
1412 | { |
1413 | struct swap_info_struct *p, *prev; |
1414 | int i; |
1415 | |
1416 | if (n <= 0) |
1417 | return; |
1418 | |
1419 | prev = NULL; |
1420 | p = NULL; |
1421 | |
1422 | /* |
1423 | * Sort swap entries by swap device, so each lock is only taken once. |
1424 | * nr_swapfiles isn't absolutely correct, but the overhead of sort() is |
1425 | * so low that it isn't necessary to optimize further. |
1426 | */ |
1427 | if (nr_swapfiles > 1) |
1428 | sort(base: entries, num: n, size: sizeof(entries[0]), cmp_func: swp_entry_cmp, NULL); |
1429 | for (i = 0; i < n; ++i) { |
1430 | p = swap_info_get_cont(entry: entries[i], q: prev); |
1431 | if (p) |
1432 | swap_entry_free(p, entry: entries[i]); |
1433 | prev = p; |
1434 | } |
1435 | if (p) |
1436 | spin_unlock(lock: &p->lock); |
1437 | } |
1438 | |
1439 | int __swap_count(swp_entry_t entry) |
1440 | { |
1441 | struct swap_info_struct *si = swp_swap_info(entry); |
1442 | pgoff_t offset = swp_offset(entry); |
1443 | |
1444 | return swap_count(ent: si->swap_map[offset]); |
1445 | } |
1446 | |
1447 | /* |
1448 | * How many references to @entry are currently swapped out? |
1449 | * This does not give an exact answer when swap count is continued, |
1450 | * but does include the high COUNT_CONTINUED flag to allow for that. |
1451 | */ |
1452 | int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry) |
1453 | { |
1454 | pgoff_t offset = swp_offset(entry); |
1455 | struct swap_cluster_info *ci; |
1456 | int count; |
1457 | |
1458 | ci = lock_cluster_or_swap_info(si, offset); |
1459 | count = swap_count(ent: si->swap_map[offset]); |
1460 | unlock_cluster_or_swap_info(si, ci); |
1461 | return count; |
1462 | } |
1463 | |
1464 | /* |
1465 | * How many references to @entry are currently swapped out? |
1466 | * This considers COUNT_CONTINUED so it returns exact answer. |
1467 | */ |
1468 | int swp_swapcount(swp_entry_t entry) |
1469 | { |
1470 | int count, tmp_count, n; |
1471 | struct swap_info_struct *p; |
1472 | struct swap_cluster_info *ci; |
1473 | struct page *page; |
1474 | pgoff_t offset; |
1475 | unsigned char *map; |
1476 | |
1477 | p = _swap_info_get(entry); |
1478 | if (!p) |
1479 | return 0; |
1480 | |
1481 | offset = swp_offset(entry); |
1482 | |
1483 | ci = lock_cluster_or_swap_info(si: p, offset); |
1484 | |
1485 | count = swap_count(ent: p->swap_map[offset]); |
1486 | if (!(count & COUNT_CONTINUED)) |
1487 | goto out; |
1488 | |
1489 | count &= ~COUNT_CONTINUED; |
1490 | n = SWAP_MAP_MAX + 1; |
1491 | |
1492 | page = vmalloc_to_page(addr: p->swap_map + offset); |
1493 | offset &= ~PAGE_MASK; |
1494 | VM_BUG_ON(page_private(page) != SWP_CONTINUED); |
1495 | |
1496 | do { |
1497 | page = list_next_entry(page, lru); |
1498 | map = kmap_atomic(page); |
1499 | tmp_count = map[offset]; |
1500 | kunmap_atomic(map); |
1501 | |
1502 | count += (tmp_count & ~COUNT_CONTINUED) * n; |
1503 | n *= (SWAP_CONT_MAX + 1); |
1504 | } while (tmp_count & COUNT_CONTINUED); |
1505 | out: |
1506 | unlock_cluster_or_swap_info(si: p, ci); |
1507 | return count; |
1508 | } |
1509 | |
1510 | static bool swap_page_trans_huge_swapped(struct swap_info_struct *si, |
1511 | swp_entry_t entry) |
1512 | { |
1513 | struct swap_cluster_info *ci; |
1514 | unsigned char *map = si->swap_map; |
1515 | unsigned long roffset = swp_offset(entry); |
1516 | unsigned long offset = round_down(roffset, SWAPFILE_CLUSTER); |
1517 | int i; |
1518 | bool ret = false; |
1519 | |
1520 | ci = lock_cluster_or_swap_info(si, offset); |
1521 | if (!ci || !cluster_is_huge(info: ci)) { |
1522 | if (swap_count(ent: map[roffset])) |
1523 | ret = true; |
1524 | goto unlock_out; |
1525 | } |
1526 | for (i = 0; i < SWAPFILE_CLUSTER; i++) { |
1527 | if (swap_count(ent: map[offset + i])) { |
1528 | ret = true; |
1529 | break; |
1530 | } |
1531 | } |
1532 | unlock_out: |
1533 | unlock_cluster_or_swap_info(si, ci); |
1534 | return ret; |
1535 | } |
1536 | |
1537 | static bool folio_swapped(struct folio *folio) |
1538 | { |
1539 | swp_entry_t entry = folio->swap; |
1540 | struct swap_info_struct *si = _swap_info_get(entry); |
1541 | |
1542 | if (!si) |
1543 | return false; |
1544 | |
1545 | if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!folio_test_large(folio))) |
1546 | return swap_swapcount(si, entry) != 0; |
1547 | |
1548 | return swap_page_trans_huge_swapped(si, entry); |
1549 | } |
1550 | |
1551 | /** |
1552 | * folio_free_swap() - Free the swap space used for this folio. |
1553 | * @folio: The folio to remove. |
1554 | * |
1555 | * If swap is getting full, or if there are no more mappings of this folio, |
1556 | * then call folio_free_swap to free its swap space. |
1557 | * |
1558 | * Return: true if we were able to release the swap space. |
1559 | */ |
1560 | bool folio_free_swap(struct folio *folio) |
1561 | { |
1562 | VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); |
1563 | |
1564 | if (!folio_test_swapcache(folio)) |
1565 | return false; |
1566 | if (folio_test_writeback(folio)) |
1567 | return false; |
1568 | if (folio_swapped(folio)) |
1569 | return false; |
1570 | |
1571 | /* |
1572 | * Once hibernation has begun to create its image of memory, |
1573 | * there's a danger that one of the calls to folio_free_swap() |
1574 | * - most probably a call from __try_to_reclaim_swap() while |
1575 | * hibernation is allocating its own swap pages for the image, |
1576 | * but conceivably even a call from memory reclaim - will free |
1577 | * the swap from a folio which has already been recorded in the |
1578 | * image as a clean swapcache folio, and then reuse its swap for |
1579 | * another page of the image. On waking from hibernation, the |
1580 | * original folio might be freed under memory pressure, then |
1581 | * later read back in from swap, now with the wrong data. |
1582 | * |
1583 | * Hibernation suspends storage while it is writing the image |
1584 | * to disk so check that here. |
1585 | */ |
1586 | if (pm_suspended_storage()) |
1587 | return false; |
1588 | |
1589 | delete_from_swap_cache(folio); |
1590 | folio_set_dirty(folio); |
1591 | return true; |
1592 | } |
1593 | |
1594 | /* |
1595 | * Free the swap entry like above, but also try to |
1596 | * free the page cache entry if it is the last user. |
1597 | */ |
1598 | int free_swap_and_cache(swp_entry_t entry) |
1599 | { |
1600 | struct swap_info_struct *p; |
1601 | unsigned char count; |
1602 | |
1603 | if (non_swap_entry(entry)) |
1604 | return 1; |
1605 | |
1606 | p = _swap_info_get(entry); |
1607 | if (p) { |
1608 | count = __swap_entry_free(p, entry); |
1609 | if (count == SWAP_HAS_CACHE && |
1610 | !swap_page_trans_huge_swapped(si: p, entry)) |
1611 | __try_to_reclaim_swap(si: p, offset: swp_offset(entry), |
1612 | TTRS_UNMAPPED | TTRS_FULL); |
1613 | } |
1614 | return p != NULL; |
1615 | } |
1616 | |
1617 | #ifdef CONFIG_HIBERNATION |
1618 | |
1619 | swp_entry_t get_swap_page_of_type(int type) |
1620 | { |
1621 | struct swap_info_struct *si = swap_type_to_swap_info(type); |
1622 | swp_entry_t entry = {0}; |
1623 | |
1624 | if (!si) |
1625 | goto fail; |
1626 | |
1627 | /* This is called for allocating swap entry, not cache */ |
1628 | spin_lock(lock: &si->lock); |
1629 | if ((si->flags & SWP_WRITEOK) && scan_swap_map_slots(si, usage: 1, nr: 1, slots: &entry)) |
1630 | atomic_long_dec(v: &nr_swap_pages); |
1631 | spin_unlock(lock: &si->lock); |
1632 | fail: |
1633 | return entry; |
1634 | } |
1635 | |
1636 | /* |
1637 | * Find the swap type that corresponds to given device (if any). |
1638 | * |
1639 | * @offset - number of the PAGE_SIZE-sized block of the device, starting |
1640 | * from 0, in which the swap header is expected to be located. |
1641 | * |
1642 | * This is needed for the suspend to disk (aka swsusp). |
1643 | */ |
1644 | int swap_type_of(dev_t device, sector_t offset) |
1645 | { |
1646 | int type; |
1647 | |
1648 | if (!device) |
1649 | return -1; |
1650 | |
1651 | spin_lock(lock: &swap_lock); |
1652 | for (type = 0; type < nr_swapfiles; type++) { |
1653 | struct swap_info_struct *sis = swap_info[type]; |
1654 | |
1655 | if (!(sis->flags & SWP_WRITEOK)) |
1656 | continue; |
1657 | |
1658 | if (device == sis->bdev->bd_dev) { |
1659 | struct swap_extent *se = first_se(sis); |
1660 | |
1661 | if (se->start_block == offset) { |
1662 | spin_unlock(lock: &swap_lock); |
1663 | return type; |
1664 | } |
1665 | } |
1666 | } |
1667 | spin_unlock(lock: &swap_lock); |
1668 | return -ENODEV; |
1669 | } |
1670 | |
1671 | int find_first_swap(dev_t *device) |
1672 | { |
1673 | int type; |
1674 | |
1675 | spin_lock(lock: &swap_lock); |
1676 | for (type = 0; type < nr_swapfiles; type++) { |
1677 | struct swap_info_struct *sis = swap_info[type]; |
1678 | |
1679 | if (!(sis->flags & SWP_WRITEOK)) |
1680 | continue; |
1681 | *device = sis->bdev->bd_dev; |
1682 | spin_unlock(lock: &swap_lock); |
1683 | return type; |
1684 | } |
1685 | spin_unlock(lock: &swap_lock); |
1686 | return -ENODEV; |
1687 | } |
1688 | |
1689 | /* |
1690 | * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev |
1691 | * corresponding to given index in swap_info (swap type). |
1692 | */ |
1693 | sector_t swapdev_block(int type, pgoff_t offset) |
1694 | { |
1695 | struct swap_info_struct *si = swap_type_to_swap_info(type); |
1696 | struct swap_extent *se; |
1697 | |
1698 | if (!si || !(si->flags & SWP_WRITEOK)) |
1699 | return 0; |
1700 | se = offset_to_swap_extent(sis: si, offset); |
1701 | return se->start_block + (offset - se->start_page); |
1702 | } |
1703 | |
1704 | /* |
1705 | * Return either the total number of swap pages of given type, or the number |
1706 | * of free pages of that type (depending on @free) |
1707 | * |
1708 | * This is needed for software suspend |
1709 | */ |
1710 | unsigned int count_swap_pages(int type, int free) |
1711 | { |
1712 | unsigned int n = 0; |
1713 | |
1714 | spin_lock(lock: &swap_lock); |
1715 | if ((unsigned int)type < nr_swapfiles) { |
1716 | struct swap_info_struct *sis = swap_info[type]; |
1717 | |
1718 | spin_lock(lock: &sis->lock); |
1719 | if (sis->flags & SWP_WRITEOK) { |
1720 | n = sis->pages; |
1721 | if (free) |
1722 | n -= sis->inuse_pages; |
1723 | } |
1724 | spin_unlock(lock: &sis->lock); |
1725 | } |
1726 | spin_unlock(lock: &swap_lock); |
1727 | return n; |
1728 | } |
1729 | #endif /* CONFIG_HIBERNATION */ |
1730 | |
1731 | static inline int pte_same_as_swp(pte_t pte, pte_t swp_pte) |
1732 | { |
1733 | return pte_same(a: pte_swp_clear_flags(pte), b: swp_pte); |
1734 | } |
1735 | |
1736 | /* |
1737 | * No need to decide whether this PTE shares the swap entry with others, |
1738 | * just let do_wp_page work it out if a write is requested later - to |
1739 | * force COW, vm_page_prot omits write permission from any private vma. |
1740 | */ |
1741 | static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, |
1742 | unsigned long addr, swp_entry_t entry, struct folio *folio) |
1743 | { |
1744 | struct page *page = folio_file_page(folio, index: swp_offset(entry)); |
1745 | struct page *swapcache; |
1746 | spinlock_t *ptl; |
1747 | pte_t *pte, new_pte, old_pte; |
1748 | bool hwpoisoned = PageHWPoison(page); |
1749 | int ret = 1; |
1750 | |
1751 | swapcache = page; |
1752 | page = ksm_might_need_to_copy(page, vma, address: addr); |
1753 | if (unlikely(!page)) |
1754 | return -ENOMEM; |
1755 | else if (unlikely(PTR_ERR(page) == -EHWPOISON)) |
1756 | hwpoisoned = true; |
1757 | |
1758 | pte = pte_offset_map_lock(mm: vma->vm_mm, pmd, addr, ptlp: &ptl); |
1759 | if (unlikely(!pte || !pte_same_as_swp(ptep_get(pte), |
1760 | swp_entry_to_pte(entry)))) { |
1761 | ret = 0; |
1762 | goto out; |
1763 | } |
1764 | |
1765 | old_pte = ptep_get(ptep: pte); |
1766 | |
1767 | if (unlikely(hwpoisoned || !PageUptodate(page))) { |
1768 | swp_entry_t swp_entry; |
1769 | |
1770 | dec_mm_counter(mm: vma->vm_mm, member: MM_SWAPENTS); |
1771 | if (hwpoisoned) { |
1772 | swp_entry = make_hwpoison_entry(page: swapcache); |
1773 | page = swapcache; |
1774 | } else { |
1775 | swp_entry = make_poisoned_swp_entry(); |
1776 | } |
1777 | new_pte = swp_entry_to_pte(entry: swp_entry); |
1778 | ret = 0; |
1779 | goto setpte; |
1780 | } |
1781 | |
1782 | /* |
1783 | * Some architectures may have to restore extra metadata to the page |
1784 | * when reading from swap. This metadata may be indexed by swap entry |
1785 | * so this must be called before swap_free(). |
1786 | */ |
1787 | arch_swap_restore(entry, page_folio(page)); |
1788 | |
1789 | /* See do_swap_page() */ |
1790 | BUG_ON(!PageAnon(page) && PageMappedToDisk(page)); |
1791 | BUG_ON(PageAnon(page) && PageAnonExclusive(page)); |
1792 | |
1793 | dec_mm_counter(mm: vma->vm_mm, member: MM_SWAPENTS); |
1794 | inc_mm_counter(mm: vma->vm_mm, member: MM_ANONPAGES); |
1795 | get_page(page); |
1796 | if (page == swapcache) { |
1797 | rmap_t rmap_flags = RMAP_NONE; |
1798 | |
1799 | /* |
1800 | * See do_swap_page(): PageWriteback() would be problematic. |
1801 | * However, we do a wait_on_page_writeback() just before this |
1802 | * call and have the page locked. |
1803 | */ |
1804 | VM_BUG_ON_PAGE(PageWriteback(page), page); |
1805 | if (pte_swp_exclusive(pte: old_pte)) |
1806 | rmap_flags |= RMAP_EXCLUSIVE; |
1807 | |
1808 | page_add_anon_rmap(page, vma, address: addr, flags: rmap_flags); |
1809 | } else { /* ksm created a completely new copy */ |
1810 | page_add_new_anon_rmap(page, vma, address: addr); |
1811 | lru_cache_add_inactive_or_unevictable(page, vma); |
1812 | } |
1813 | new_pte = pte_mkold(mk_pte(page, vma->vm_page_prot)); |
1814 | if (pte_swp_soft_dirty(pte: old_pte)) |
1815 | new_pte = pte_mksoft_dirty(pte: new_pte); |
1816 | if (pte_swp_uffd_wp(pte: old_pte)) |
1817 | new_pte = pte_mkuffd_wp(pte: new_pte); |
1818 | setpte: |
1819 | set_pte_at(vma->vm_mm, addr, pte, new_pte); |
1820 | swap_free(entry); |
1821 | out: |
1822 | if (pte) |
1823 | pte_unmap_unlock(pte, ptl); |
1824 | if (page != swapcache) { |
1825 | unlock_page(page); |
1826 | put_page(page); |
1827 | } |
1828 | return ret; |
1829 | } |
1830 | |
1831 | static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, |
1832 | unsigned long addr, unsigned long end, |
1833 | unsigned int type) |
1834 | { |
1835 | pte_t *pte = NULL; |
1836 | struct swap_info_struct *si; |
1837 | |
1838 | si = swap_info[type]; |
1839 | do { |
1840 | struct folio *folio; |
1841 | unsigned long offset; |
1842 | unsigned char swp_count; |
1843 | swp_entry_t entry; |
1844 | int ret; |
1845 | pte_t ptent; |
1846 | |
1847 | if (!pte++) { |
1848 | pte = pte_offset_map(pmd, addr); |
1849 | if (!pte) |
1850 | break; |
1851 | } |
1852 | |
1853 | ptent = ptep_get_lockless(ptep: pte); |
1854 | |
1855 | if (!is_swap_pte(pte: ptent)) |
1856 | continue; |
1857 | |
1858 | entry = pte_to_swp_entry(pte: ptent); |
1859 | if (swp_type(entry) != type) |
1860 | continue; |
1861 | |
1862 | offset = swp_offset(entry); |
1863 | pte_unmap(pte); |
1864 | pte = NULL; |
1865 | |
1866 | folio = swap_cache_get_folio(entry, vma, addr); |
1867 | if (!folio) { |
1868 | struct page *page; |
1869 | struct vm_fault vmf = { |
1870 | .vma = vma, |
1871 | .address = addr, |
1872 | .real_address = addr, |
1873 | .pmd = pmd, |
1874 | }; |
1875 | |
1876 | page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, |
1877 | vmf: &vmf); |
1878 | if (page) |
1879 | folio = page_folio(page); |
1880 | } |
1881 | if (!folio) { |
1882 | swp_count = READ_ONCE(si->swap_map[offset]); |
1883 | if (swp_count == 0 || swp_count == SWAP_MAP_BAD) |
1884 | continue; |
1885 | return -ENOMEM; |
1886 | } |
1887 | |
1888 | folio_lock(folio); |
1889 | folio_wait_writeback(folio); |
1890 | ret = unuse_pte(vma, pmd, addr, entry, folio); |
1891 | if (ret < 0) { |
1892 | folio_unlock(folio); |
1893 | folio_put(folio); |
1894 | return ret; |
1895 | } |
1896 | |
1897 | folio_free_swap(folio); |
1898 | folio_unlock(folio); |
1899 | folio_put(folio); |
1900 | } while (addr += PAGE_SIZE, addr != end); |
1901 | |
1902 | if (pte) |
1903 | pte_unmap(pte); |
1904 | return 0; |
1905 | } |
1906 | |
1907 | static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, |
1908 | unsigned long addr, unsigned long end, |
1909 | unsigned int type) |
1910 | { |
1911 | pmd_t *pmd; |
1912 | unsigned long next; |
1913 | int ret; |
1914 | |
1915 | pmd = pmd_offset(pud, address: addr); |
1916 | do { |
1917 | cond_resched(); |
1918 | next = pmd_addr_end(addr, end); |
1919 | ret = unuse_pte_range(vma, pmd, addr, end: next, type); |
1920 | if (ret) |
1921 | return ret; |
1922 | } while (pmd++, addr = next, addr != end); |
1923 | return 0; |
1924 | } |
1925 | |
1926 | static inline int unuse_pud_range(struct vm_area_struct *vma, p4d_t *p4d, |
1927 | unsigned long addr, unsigned long end, |
1928 | unsigned int type) |
1929 | { |
1930 | pud_t *pud; |
1931 | unsigned long next; |
1932 | int ret; |
1933 | |
1934 | pud = pud_offset(p4d, address: addr); |
1935 | do { |
1936 | next = pud_addr_end(addr, end); |
1937 | if (pud_none_or_clear_bad(pud)) |
1938 | continue; |
1939 | ret = unuse_pmd_range(vma, pud, addr, end: next, type); |
1940 | if (ret) |
1941 | return ret; |
1942 | } while (pud++, addr = next, addr != end); |
1943 | return 0; |
1944 | } |
1945 | |
1946 | static inline int unuse_p4d_range(struct vm_area_struct *vma, pgd_t *pgd, |
1947 | unsigned long addr, unsigned long end, |
1948 | unsigned int type) |
1949 | { |
1950 | p4d_t *p4d; |
1951 | unsigned long next; |
1952 | int ret; |
1953 | |
1954 | p4d = p4d_offset(pgd, address: addr); |
1955 | do { |
1956 | next = p4d_addr_end(addr, end); |
1957 | if (p4d_none_or_clear_bad(p4d)) |
1958 | continue; |
1959 | ret = unuse_pud_range(vma, p4d, addr, end: next, type); |
1960 | if (ret) |
1961 | return ret; |
1962 | } while (p4d++, addr = next, addr != end); |
1963 | return 0; |
1964 | } |
1965 | |
1966 | static int unuse_vma(struct vm_area_struct *vma, unsigned int type) |
1967 | { |
1968 | pgd_t *pgd; |
1969 | unsigned long addr, end, next; |
1970 | int ret; |
1971 | |
1972 | addr = vma->vm_start; |
1973 | end = vma->vm_end; |
1974 | |
1975 | pgd = pgd_offset(vma->vm_mm, addr); |
1976 | do { |
1977 | next = pgd_addr_end(addr, end); |
1978 | if (pgd_none_or_clear_bad(pgd)) |
1979 | continue; |
1980 | ret = unuse_p4d_range(vma, pgd, addr, end: next, type); |
1981 | if (ret) |
1982 | return ret; |
1983 | } while (pgd++, addr = next, addr != end); |
1984 | return 0; |
1985 | } |
1986 | |
1987 | static int unuse_mm(struct mm_struct *mm, unsigned int type) |
1988 | { |
1989 | struct vm_area_struct *vma; |
1990 | int ret = 0; |
1991 | VMA_ITERATOR(vmi, mm, 0); |
1992 | |
1993 | mmap_read_lock(mm); |
1994 | for_each_vma(vmi, vma) { |
1995 | if (vma->anon_vma) { |
1996 | ret = unuse_vma(vma, type); |
1997 | if (ret) |
1998 | break; |
1999 | } |
2000 | |
2001 | cond_resched(); |
2002 | } |
2003 | mmap_read_unlock(mm); |
2004 | return ret; |
2005 | } |
2006 | |
2007 | /* |
2008 | * Scan swap_map from current position to next entry still in use. |
2009 | * Return 0 if there are no inuse entries after prev till end of |
2010 | * the map. |
2011 | */ |
2012 | static unsigned int find_next_to_unuse(struct swap_info_struct *si, |
2013 | unsigned int prev) |
2014 | { |
2015 | unsigned int i; |
2016 | unsigned char count; |
2017 | |
2018 | /* |
2019 | * No need for swap_lock here: we're just looking |
2020 | * for whether an entry is in use, not modifying it; false |
2021 | * hits are okay, and sys_swapoff() has already prevented new |
2022 | * allocations from this area (while holding swap_lock). |
2023 | */ |
2024 | for (i = prev + 1; i < si->max; i++) { |
2025 | count = READ_ONCE(si->swap_map[i]); |
2026 | if (count && swap_count(ent: count) != SWAP_MAP_BAD) |
2027 | break; |
2028 | if ((i % LATENCY_LIMIT) == 0) |
2029 | cond_resched(); |
2030 | } |
2031 | |
2032 | if (i == si->max) |
2033 | i = 0; |
2034 | |
2035 | return i; |
2036 | } |
2037 | |
2038 | static int try_to_unuse(unsigned int type) |
2039 | { |
2040 | struct mm_struct *prev_mm; |
2041 | struct mm_struct *mm; |
2042 | struct list_head *p; |
2043 | int retval = 0; |
2044 | struct swap_info_struct *si = swap_info[type]; |
2045 | struct folio *folio; |
2046 | swp_entry_t entry; |
2047 | unsigned int i; |
2048 | |
2049 | if (!READ_ONCE(si->inuse_pages)) |
2050 | return 0; |
2051 | |
2052 | retry: |
2053 | retval = shmem_unuse(type); |
2054 | if (retval) |
2055 | return retval; |
2056 | |
2057 | prev_mm = &init_mm; |
2058 | mmget(mm: prev_mm); |
2059 | |
2060 | spin_lock(lock: &mmlist_lock); |
2061 | p = &init_mm.mmlist; |
2062 | while (READ_ONCE(si->inuse_pages) && |
2063 | !signal_pending(current) && |
2064 | (p = p->next) != &init_mm.mmlist) { |
2065 | |
2066 | mm = list_entry(p, struct mm_struct, mmlist); |
2067 | if (!mmget_not_zero(mm)) |
2068 | continue; |
2069 | spin_unlock(lock: &mmlist_lock); |
2070 | mmput(prev_mm); |
2071 | prev_mm = mm; |
2072 | retval = unuse_mm(mm, type); |
2073 | if (retval) { |
2074 | mmput(prev_mm); |
2075 | return retval; |
2076 | } |
2077 | |
2078 | /* |
2079 | * Make sure that we aren't completely killing |
2080 | * interactive performance. |
2081 | */ |
2082 | cond_resched(); |
2083 | spin_lock(lock: &mmlist_lock); |
2084 | } |
2085 | spin_unlock(lock: &mmlist_lock); |
2086 | |
2087 | mmput(prev_mm); |
2088 | |
2089 | i = 0; |
2090 | while (READ_ONCE(si->inuse_pages) && |
2091 | !signal_pending(current) && |
2092 | (i = find_next_to_unuse(si, prev: i)) != 0) { |
2093 | |
2094 | entry = swp_entry(type, offset: i); |
2095 | folio = filemap_get_folio(swap_address_space(entry), index: i); |
2096 | if (IS_ERR(ptr: folio)) |
2097 | continue; |
2098 | |
2099 | /* |
2100 | * It is conceivable that a racing task removed this folio from |
2101 | * swap cache just before we acquired the page lock. The folio |
2102 | * might even be back in swap cache on another swap area. But |
2103 | * that is okay, folio_free_swap() only removes stale folios. |
2104 | */ |
2105 | folio_lock(folio); |
2106 | folio_wait_writeback(folio); |
2107 | folio_free_swap(folio); |
2108 | folio_unlock(folio); |
2109 | folio_put(folio); |
2110 | } |
2111 | |
2112 | /* |
2113 | * Lets check again to see if there are still swap entries in the map. |
2114 | * If yes, we would need to do retry the unuse logic again. |
2115 | * Under global memory pressure, swap entries can be reinserted back |
2116 | * into process space after the mmlist loop above passes over them. |
2117 | * |
2118 | * Limit the number of retries? No: when mmget_not_zero() |
2119 | * above fails, that mm is likely to be freeing swap from |
2120 | * exit_mmap(), which proceeds at its own independent pace; |
2121 | * and even shmem_writepage() could have been preempted after |
2122 | * folio_alloc_swap(), temporarily hiding that swap. It's easy |
2123 | * and robust (though cpu-intensive) just to keep retrying. |
2124 | */ |
2125 | if (READ_ONCE(si->inuse_pages)) { |
2126 | if (!signal_pending(current)) |
2127 | goto retry; |
2128 | return -EINTR; |
2129 | } |
2130 | |
2131 | return 0; |
2132 | } |
2133 | |
2134 | /* |
2135 | * After a successful try_to_unuse, if no swap is now in use, we know |
2136 | * we can empty the mmlist. swap_lock must be held on entry and exit. |
2137 | * Note that mmlist_lock nests inside swap_lock, and an mm must be |
2138 | * added to the mmlist just after page_duplicate - before would be racy. |
2139 | */ |
2140 | static void drain_mmlist(void) |
2141 | { |
2142 | struct list_head *p, *next; |
2143 | unsigned int type; |
2144 | |
2145 | for (type = 0; type < nr_swapfiles; type++) |
2146 | if (swap_info[type]->inuse_pages) |
2147 | return; |
2148 | spin_lock(lock: &mmlist_lock); |
2149 | list_for_each_safe(p, next, &init_mm.mmlist) |
2150 | list_del_init(entry: p); |
2151 | spin_unlock(lock: &mmlist_lock); |
2152 | } |
2153 | |
2154 | /* |
2155 | * Free all of a swapdev's extent information |
2156 | */ |
2157 | static void destroy_swap_extents(struct swap_info_struct *sis) |
2158 | { |
2159 | while (!RB_EMPTY_ROOT(&sis->swap_extent_root)) { |
2160 | struct rb_node *rb = sis->swap_extent_root.rb_node; |
2161 | struct swap_extent *se = rb_entry(rb, struct swap_extent, rb_node); |
2162 | |
2163 | rb_erase(rb, &sis->swap_extent_root); |
2164 | kfree(objp: se); |
2165 | } |
2166 | |
2167 | if (sis->flags & SWP_ACTIVATED) { |
2168 | struct file *swap_file = sis->swap_file; |
2169 | struct address_space *mapping = swap_file->f_mapping; |
2170 | |
2171 | sis->flags &= ~SWP_ACTIVATED; |
2172 | if (mapping->a_ops->swap_deactivate) |
2173 | mapping->a_ops->swap_deactivate(swap_file); |
2174 | } |
2175 | } |
2176 | |
2177 | /* |
2178 | * Add a block range (and the corresponding page range) into this swapdev's |
2179 | * extent tree. |
2180 | * |
2181 | * This function rather assumes that it is called in ascending page order. |
2182 | */ |
2183 | int |
2184 | add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, |
2185 | unsigned long nr_pages, sector_t start_block) |
2186 | { |
2187 | struct rb_node **link = &sis->swap_extent_root.rb_node, *parent = NULL; |
2188 | struct swap_extent *se; |
2189 | struct swap_extent *new_se; |
2190 | |
2191 | /* |
2192 | * place the new node at the right most since the |
2193 | * function is called in ascending page order. |
2194 | */ |
2195 | while (*link) { |
2196 | parent = *link; |
2197 | link = &parent->rb_right; |
2198 | } |
2199 | |
2200 | if (parent) { |
2201 | se = rb_entry(parent, struct swap_extent, rb_node); |
2202 | BUG_ON(se->start_page + se->nr_pages != start_page); |
2203 | if (se->start_block + se->nr_pages == start_block) { |
2204 | /* Merge it */ |
2205 | se->nr_pages += nr_pages; |
2206 | return 0; |
2207 | } |
2208 | } |
2209 | |
2210 | /* No merge, insert a new extent. */ |
2211 | new_se = kmalloc(size: sizeof(*se), GFP_KERNEL); |
2212 | if (new_se == NULL) |
2213 | return -ENOMEM; |
2214 | new_se->start_page = start_page; |
2215 | new_se->nr_pages = nr_pages; |
2216 | new_se->start_block = start_block; |
2217 | |
2218 | rb_link_node(node: &new_se->rb_node, parent, rb_link: link); |
2219 | rb_insert_color(&new_se->rb_node, &sis->swap_extent_root); |
2220 | return 1; |
2221 | } |
2222 | EXPORT_SYMBOL_GPL(add_swap_extent); |
2223 | |
2224 | /* |
2225 | * A `swap extent' is a simple thing which maps a contiguous range of pages |
2226 | * onto a contiguous range of disk blocks. A rbtree of swap extents is |
2227 | * built at swapon time and is then used at swap_writepage/swap_readpage |
2228 | * time for locating where on disk a page belongs. |
2229 | * |
2230 | * If the swapfile is an S_ISBLK block device, a single extent is installed. |
2231 | * This is done so that the main operating code can treat S_ISBLK and S_ISREG |
2232 | * swap files identically. |
2233 | * |
2234 | * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap |
2235 | * extent rbtree operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK |
2236 | * swapfiles are handled *identically* after swapon time. |
2237 | * |
2238 | * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks |
2239 | * and will parse them into a rbtree, in PAGE_SIZE chunks. If some stray |
2240 | * blocks are found which do not fall within the PAGE_SIZE alignment |
2241 | * requirements, they are simply tossed out - we will never use those blocks |
2242 | * for swapping. |
2243 | * |
2244 | * For all swap devices we set S_SWAPFILE across the life of the swapon. This |
2245 | * prevents users from writing to the swap device, which will corrupt memory. |
2246 | * |
2247 | * The amount of disk space which a single swap extent represents varies. |
2248 | * Typically it is in the 1-4 megabyte range. So we can have hundreds of |
2249 | * extents in the rbtree. - akpm. |
2250 | */ |
2251 | static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) |
2252 | { |
2253 | struct file *swap_file = sis->swap_file; |
2254 | struct address_space *mapping = swap_file->f_mapping; |
2255 | struct inode *inode = mapping->host; |
2256 | int ret; |
2257 | |
2258 | if (S_ISBLK(inode->i_mode)) { |
2259 | ret = add_swap_extent(sis, 0, sis->max, 0); |
2260 | *span = sis->pages; |
2261 | return ret; |
2262 | } |
2263 | |
2264 | if (mapping->a_ops->swap_activate) { |
2265 | ret = mapping->a_ops->swap_activate(sis, swap_file, span); |
2266 | if (ret < 0) |
2267 | return ret; |
2268 | sis->flags |= SWP_ACTIVATED; |
2269 | if ((sis->flags & SWP_FS_OPS) && |
2270 | sio_pool_init() != 0) { |
2271 | destroy_swap_extents(sis); |
2272 | return -ENOMEM; |
2273 | } |
2274 | return ret; |
2275 | } |
2276 | |
2277 | return generic_swapfile_activate(sis, swap_file, span); |
2278 | } |
2279 | |
2280 | static int swap_node(struct swap_info_struct *p) |
2281 | { |
2282 | struct block_device *bdev; |
2283 | |
2284 | if (p->bdev) |
2285 | bdev = p->bdev; |
2286 | else |
2287 | bdev = p->swap_file->f_inode->i_sb->s_bdev; |
2288 | |
2289 | return bdev ? bdev->bd_disk->node_id : NUMA_NO_NODE; |
2290 | } |
2291 | |
2292 | static void setup_swap_info(struct swap_info_struct *p, int prio, |
2293 | unsigned char *swap_map, |
2294 | struct swap_cluster_info *cluster_info) |
2295 | { |
2296 | int i; |
2297 | |
2298 | if (prio >= 0) |
2299 | p->prio = prio; |
2300 | else |
2301 | p->prio = --least_priority; |
2302 | /* |
2303 | * the plist prio is negated because plist ordering is |
2304 | * low-to-high, while swap ordering is high-to-low |
2305 | */ |
2306 | p->list.prio = -p->prio; |
2307 | for_each_node(i) { |
2308 | if (p->prio >= 0) |
2309 | p->avail_lists[i].prio = -p->prio; |
2310 | else { |
2311 | if (swap_node(p) == i) |
2312 | p->avail_lists[i].prio = 1; |
2313 | else |
2314 | p->avail_lists[i].prio = -p->prio; |
2315 | } |
2316 | } |
2317 | p->swap_map = swap_map; |
2318 | p->cluster_info = cluster_info; |
2319 | } |
2320 | |
2321 | static void _enable_swap_info(struct swap_info_struct *p) |
2322 | { |
2323 | p->flags |= SWP_WRITEOK; |
2324 | atomic_long_add(i: p->pages, v: &nr_swap_pages); |
2325 | total_swap_pages += p->pages; |
2326 | |
2327 | assert_spin_locked(&swap_lock); |
2328 | /* |
2329 | * both lists are plists, and thus priority ordered. |
2330 | * swap_active_head needs to be priority ordered for swapoff(), |
2331 | * which on removal of any swap_info_struct with an auto-assigned |
2332 | * (i.e. negative) priority increments the auto-assigned priority |
2333 | * of any lower-priority swap_info_structs. |
2334 | * swap_avail_head needs to be priority ordered for folio_alloc_swap(), |
2335 | * which allocates swap pages from the highest available priority |
2336 | * swap_info_struct. |
2337 | */ |
2338 | plist_add(node: &p->list, head: &swap_active_head); |
2339 | |
2340 | /* add to available list iff swap device is not full */ |
2341 | if (p->highest_bit) |
2342 | add_to_avail_list(p); |
2343 | } |
2344 | |
2345 | static void enable_swap_info(struct swap_info_struct *p, int prio, |
2346 | unsigned char *swap_map, |
2347 | struct swap_cluster_info *cluster_info) |
2348 | { |
2349 | zswap_swapon(type: p->type); |
2350 | |
2351 | spin_lock(lock: &swap_lock); |
2352 | spin_lock(lock: &p->lock); |
2353 | setup_swap_info(p, prio, swap_map, cluster_info); |
2354 | spin_unlock(lock: &p->lock); |
2355 | spin_unlock(lock: &swap_lock); |
2356 | /* |
2357 | * Finished initializing swap device, now it's safe to reference it. |
2358 | */ |
2359 | percpu_ref_resurrect(ref: &p->users); |
2360 | spin_lock(lock: &swap_lock); |
2361 | spin_lock(lock: &p->lock); |
2362 | _enable_swap_info(p); |
2363 | spin_unlock(lock: &p->lock); |
2364 | spin_unlock(lock: &swap_lock); |
2365 | } |
2366 | |
2367 | static void reinsert_swap_info(struct swap_info_struct *p) |
2368 | { |
2369 | spin_lock(lock: &swap_lock); |
2370 | spin_lock(lock: &p->lock); |
2371 | setup_swap_info(p, prio: p->prio, swap_map: p->swap_map, cluster_info: p->cluster_info); |
2372 | _enable_swap_info(p); |
2373 | spin_unlock(lock: &p->lock); |
2374 | spin_unlock(lock: &swap_lock); |
2375 | } |
2376 | |
2377 | bool has_usable_swap(void) |
2378 | { |
2379 | bool ret = true; |
2380 | |
2381 | spin_lock(lock: &swap_lock); |
2382 | if (plist_head_empty(head: &swap_active_head)) |
2383 | ret = false; |
2384 | spin_unlock(lock: &swap_lock); |
2385 | return ret; |
2386 | } |
2387 | |
2388 | SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) |
2389 | { |
2390 | struct swap_info_struct *p = NULL; |
2391 | unsigned char *swap_map; |
2392 | struct swap_cluster_info *cluster_info; |
2393 | struct file *swap_file, *victim; |
2394 | struct address_space *mapping; |
2395 | struct inode *inode; |
2396 | struct filename *pathname; |
2397 | int err, found = 0; |
2398 | unsigned int old_block_size; |
2399 | |
2400 | if (!capable(CAP_SYS_ADMIN)) |
2401 | return -EPERM; |
2402 | |
2403 | BUG_ON(!current->mm); |
2404 | |
2405 | pathname = getname(specialfile); |
2406 | if (IS_ERR(ptr: pathname)) |
2407 | return PTR_ERR(ptr: pathname); |
2408 | |
2409 | victim = file_open_name(pathname, O_RDWR|O_LARGEFILE, 0); |
2410 | err = PTR_ERR(ptr: victim); |
2411 | if (IS_ERR(ptr: victim)) |
2412 | goto out; |
2413 | |
2414 | mapping = victim->f_mapping; |
2415 | spin_lock(lock: &swap_lock); |
2416 | plist_for_each_entry(p, &swap_active_head, list) { |
2417 | if (p->flags & SWP_WRITEOK) { |
2418 | if (p->swap_file->f_mapping == mapping) { |
2419 | found = 1; |
2420 | break; |
2421 | } |
2422 | } |
2423 | } |
2424 | if (!found) { |
2425 | err = -EINVAL; |
2426 | spin_unlock(lock: &swap_lock); |
2427 | goto out_dput; |
2428 | } |
2429 | if (!security_vm_enough_memory_mm(current->mm, pages: p->pages)) |
2430 | vm_unacct_memory(pages: p->pages); |
2431 | else { |
2432 | err = -ENOMEM; |
2433 | spin_unlock(lock: &swap_lock); |
2434 | goto out_dput; |
2435 | } |
2436 | spin_lock(lock: &p->lock); |
2437 | del_from_avail_list(p); |
2438 | if (p->prio < 0) { |
2439 | struct swap_info_struct *si = p; |
2440 | int nid; |
2441 | |
2442 | plist_for_each_entry_continue(si, &swap_active_head, list) { |
2443 | si->prio++; |
2444 | si->list.prio--; |
2445 | for_each_node(nid) { |
2446 | if (si->avail_lists[nid].prio != 1) |
2447 | si->avail_lists[nid].prio--; |
2448 | } |
2449 | } |
2450 | least_priority++; |
2451 | } |
2452 | plist_del(node: &p->list, head: &swap_active_head); |
2453 | atomic_long_sub(i: p->pages, v: &nr_swap_pages); |
2454 | total_swap_pages -= p->pages; |
2455 | p->flags &= ~SWP_WRITEOK; |
2456 | spin_unlock(lock: &p->lock); |
2457 | spin_unlock(lock: &swap_lock); |
2458 | |
2459 | disable_swap_slots_cache_lock(); |
2460 | |
2461 | set_current_oom_origin(); |
2462 | err = try_to_unuse(type: p->type); |
2463 | clear_current_oom_origin(); |
2464 | |
2465 | if (err) { |
2466 | /* re-insert swap space back into swap_list */ |
2467 | reinsert_swap_info(p); |
2468 | reenable_swap_slots_cache_unlock(); |
2469 | goto out_dput; |
2470 | } |
2471 | |
2472 | reenable_swap_slots_cache_unlock(); |
2473 | |
2474 | /* |
2475 | * Wait for swap operations protected by get/put_swap_device() |
2476 | * to complete. |
2477 | * |
2478 | * We need synchronize_rcu() here to protect the accessing to |
2479 | * the swap cache data structure. |
2480 | */ |
2481 | percpu_ref_kill(ref: &p->users); |
2482 | synchronize_rcu(); |
2483 | wait_for_completion(&p->comp); |
2484 | |
2485 | flush_work(work: &p->discard_work); |
2486 | |
2487 | destroy_swap_extents(sis: p); |
2488 | if (p->flags & SWP_CONTINUED) |
2489 | free_swap_count_continuations(p); |
2490 | |
2491 | if (!p->bdev || !bdev_nonrot(bdev: p->bdev)) |
2492 | atomic_dec(v: &nr_rotate_swap); |
2493 | |
2494 | mutex_lock(&swapon_mutex); |
2495 | spin_lock(lock: &swap_lock); |
2496 | spin_lock(lock: &p->lock); |
2497 | drain_mmlist(); |
2498 | |
2499 | /* wait for anyone still in scan_swap_map_slots */ |
2500 | p->highest_bit = 0; /* cuts scans short */ |
2501 | while (p->flags >= SWP_SCANNING) { |
2502 | spin_unlock(lock: &p->lock); |
2503 | spin_unlock(lock: &swap_lock); |
2504 | schedule_timeout_uninterruptible(timeout: 1); |
2505 | spin_lock(lock: &swap_lock); |
2506 | spin_lock(lock: &p->lock); |
2507 | } |
2508 | |
2509 | swap_file = p->swap_file; |
2510 | old_block_size = p->old_block_size; |
2511 | p->swap_file = NULL; |
2512 | p->max = 0; |
2513 | swap_map = p->swap_map; |
2514 | p->swap_map = NULL; |
2515 | cluster_info = p->cluster_info; |
2516 | p->cluster_info = NULL; |
2517 | spin_unlock(lock: &p->lock); |
2518 | spin_unlock(lock: &swap_lock); |
2519 | arch_swap_invalidate_area(type: p->type); |
2520 | zswap_swapoff(type: p->type); |
2521 | mutex_unlock(lock: &swapon_mutex); |
2522 | free_percpu(pdata: p->percpu_cluster); |
2523 | p->percpu_cluster = NULL; |
2524 | free_percpu(pdata: p->cluster_next_cpu); |
2525 | p->cluster_next_cpu = NULL; |
2526 | vfree(addr: swap_map); |
2527 | kvfree(addr: cluster_info); |
2528 | /* Destroy swap account information */ |
2529 | swap_cgroup_swapoff(type: p->type); |
2530 | exit_swap_address_space(type: p->type); |
2531 | |
2532 | inode = mapping->host; |
2533 | if (p->bdev_handle) { |
2534 | set_blocksize(bdev: p->bdev, size: old_block_size); |
2535 | bdev_release(handle: p->bdev_handle); |
2536 | p->bdev_handle = NULL; |
2537 | } |
2538 | |
2539 | inode_lock(inode); |
2540 | inode->i_flags &= ~S_SWAPFILE; |
2541 | inode_unlock(inode); |
2542 | filp_close(swap_file, NULL); |
2543 | |
2544 | /* |
2545 | * Clear the SWP_USED flag after all resources are freed so that swapon |
2546 | * can reuse this swap_info in alloc_swap_info() safely. It is ok to |
2547 | * not hold p->lock after we cleared its SWP_WRITEOK. |
2548 | */ |
2549 | spin_lock(lock: &swap_lock); |
2550 | p->flags = 0; |
2551 | spin_unlock(lock: &swap_lock); |
2552 | |
2553 | err = 0; |
2554 | atomic_inc(v: &proc_poll_event); |
2555 | wake_up_interruptible(&proc_poll_wait); |
2556 | |
2557 | out_dput: |
2558 | filp_close(victim, NULL); |
2559 | out: |
2560 | putname(name: pathname); |
2561 | return err; |
2562 | } |
2563 | |
2564 | #ifdef CONFIG_PROC_FS |
2565 | static __poll_t swaps_poll(struct file *file, poll_table *wait) |
2566 | { |
2567 | struct seq_file *seq = file->private_data; |
2568 | |
2569 | poll_wait(filp: file, wait_address: &proc_poll_wait, p: wait); |
2570 | |
2571 | if (seq->poll_event != atomic_read(v: &proc_poll_event)) { |
2572 | seq->poll_event = atomic_read(v: &proc_poll_event); |
2573 | return EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI; |
2574 | } |
2575 | |
2576 | return EPOLLIN | EPOLLRDNORM; |
2577 | } |
2578 | |
2579 | /* iterator */ |
2580 | static void *swap_start(struct seq_file *swap, loff_t *pos) |
2581 | { |
2582 | struct swap_info_struct *si; |
2583 | int type; |
2584 | loff_t l = *pos; |
2585 | |
2586 | mutex_lock(&swapon_mutex); |
2587 | |
2588 | if (!l) |
2589 | return SEQ_START_TOKEN; |
2590 | |
2591 | for (type = 0; (si = swap_type_to_swap_info(type)); type++) { |
2592 | if (!(si->flags & SWP_USED) || !si->swap_map) |
2593 | continue; |
2594 | if (!--l) |
2595 | return si; |
2596 | } |
2597 | |
2598 | return NULL; |
2599 | } |
2600 | |
2601 | static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) |
2602 | { |
2603 | struct swap_info_struct *si = v; |
2604 | int type; |
2605 | |
2606 | if (v == SEQ_START_TOKEN) |
2607 | type = 0; |
2608 | else |
2609 | type = si->type + 1; |
2610 | |
2611 | ++(*pos); |
2612 | for (; (si = swap_type_to_swap_info(type)); type++) { |
2613 | if (!(si->flags & SWP_USED) || !si->swap_map) |
2614 | continue; |
2615 | return si; |
2616 | } |
2617 | |
2618 | return NULL; |
2619 | } |
2620 | |
2621 | static void swap_stop(struct seq_file *swap, void *v) |
2622 | { |
2623 | mutex_unlock(lock: &swapon_mutex); |
2624 | } |
2625 | |
2626 | static int swap_show(struct seq_file *swap, void *v) |
2627 | { |
2628 | struct swap_info_struct *si = v; |
2629 | struct file *file; |
2630 | int len; |
2631 | unsigned long bytes, inuse; |
2632 | |
2633 | if (si == SEQ_START_TOKEN) { |
2634 | seq_puts(m: swap, s: "Filename\t\t\t\tType\t\tSize\t\tUsed\t\tPriority\n" ); |
2635 | return 0; |
2636 | } |
2637 | |
2638 | bytes = K(si->pages); |
2639 | inuse = K(READ_ONCE(si->inuse_pages)); |
2640 | |
2641 | file = si->swap_file; |
2642 | len = seq_file_path(swap, file, " \t\n\\" ); |
2643 | seq_printf(m: swap, fmt: "%*s%s\t%lu\t%s%lu\t%s%d\n" , |
2644 | len < 40 ? 40 - len : 1, " " , |
2645 | S_ISBLK(file_inode(file)->i_mode) ? |
2646 | "partition" : "file\t" , |
2647 | bytes, bytes < 10000000 ? "\t" : "" , |
2648 | inuse, inuse < 10000000 ? "\t" : "" , |
2649 | si->prio); |
2650 | return 0; |
2651 | } |
2652 | |
2653 | static const struct seq_operations swaps_op = { |
2654 | .start = swap_start, |
2655 | .next = swap_next, |
2656 | .stop = swap_stop, |
2657 | .show = swap_show |
2658 | }; |
2659 | |
2660 | static int swaps_open(struct inode *inode, struct file *file) |
2661 | { |
2662 | struct seq_file *seq; |
2663 | int ret; |
2664 | |
2665 | ret = seq_open(file, &swaps_op); |
2666 | if (ret) |
2667 | return ret; |
2668 | |
2669 | seq = file->private_data; |
2670 | seq->poll_event = atomic_read(v: &proc_poll_event); |
2671 | return 0; |
2672 | } |
2673 | |
2674 | static const struct proc_ops swaps_proc_ops = { |
2675 | .proc_flags = PROC_ENTRY_PERMANENT, |
2676 | .proc_open = swaps_open, |
2677 | .proc_read = seq_read, |
2678 | .proc_lseek = seq_lseek, |
2679 | .proc_release = seq_release, |
2680 | .proc_poll = swaps_poll, |
2681 | }; |
2682 | |
2683 | static int __init procswaps_init(void) |
2684 | { |
2685 | proc_create(name: "swaps" , mode: 0, NULL, proc_ops: &swaps_proc_ops); |
2686 | return 0; |
2687 | } |
2688 | __initcall(procswaps_init); |
2689 | #endif /* CONFIG_PROC_FS */ |
2690 | |
2691 | #ifdef MAX_SWAPFILES_CHECK |
2692 | static int __init max_swapfiles_check(void) |
2693 | { |
2694 | MAX_SWAPFILES_CHECK(); |
2695 | return 0; |
2696 | } |
2697 | late_initcall(max_swapfiles_check); |
2698 | #endif |
2699 | |
2700 | static struct swap_info_struct *alloc_swap_info(void) |
2701 | { |
2702 | struct swap_info_struct *p; |
2703 | struct swap_info_struct *defer = NULL; |
2704 | unsigned int type; |
2705 | int i; |
2706 | |
2707 | p = kvzalloc(struct_size(p, avail_lists, nr_node_ids), GFP_KERNEL); |
2708 | if (!p) |
2709 | return ERR_PTR(error: -ENOMEM); |
2710 | |
2711 | if (percpu_ref_init(ref: &p->users, release: swap_users_ref_free, |
2712 | flags: PERCPU_REF_INIT_DEAD, GFP_KERNEL)) { |
2713 | kvfree(addr: p); |
2714 | return ERR_PTR(error: -ENOMEM); |
2715 | } |
2716 | |
2717 | spin_lock(lock: &swap_lock); |
2718 | for (type = 0; type < nr_swapfiles; type++) { |
2719 | if (!(swap_info[type]->flags & SWP_USED)) |
2720 | break; |
2721 | } |
2722 | if (type >= MAX_SWAPFILES) { |
2723 | spin_unlock(lock: &swap_lock); |
2724 | percpu_ref_exit(ref: &p->users); |
2725 | kvfree(addr: p); |
2726 | return ERR_PTR(error: -EPERM); |
2727 | } |
2728 | if (type >= nr_swapfiles) { |
2729 | p->type = type; |
2730 | /* |
2731 | * Publish the swap_info_struct after initializing it. |
2732 | * Note that kvzalloc() above zeroes all its fields. |
2733 | */ |
2734 | smp_store_release(&swap_info[type], p); /* rcu_assign_pointer() */ |
2735 | nr_swapfiles++; |
2736 | } else { |
2737 | defer = p; |
2738 | p = swap_info[type]; |
2739 | /* |
2740 | * Do not memset this entry: a racing procfs swap_next() |
2741 | * would be relying on p->type to remain valid. |
2742 | */ |
2743 | } |
2744 | p->swap_extent_root = RB_ROOT; |
2745 | plist_node_init(node: &p->list, prio: 0); |
2746 | for_each_node(i) |
2747 | plist_node_init(node: &p->avail_lists[i], prio: 0); |
2748 | p->flags = SWP_USED; |
2749 | spin_unlock(lock: &swap_lock); |
2750 | if (defer) { |
2751 | percpu_ref_exit(ref: &defer->users); |
2752 | kvfree(addr: defer); |
2753 | } |
2754 | spin_lock_init(&p->lock); |
2755 | spin_lock_init(&p->cont_lock); |
2756 | init_completion(x: &p->comp); |
2757 | |
2758 | return p; |
2759 | } |
2760 | |
2761 | static int claim_swapfile(struct swap_info_struct *p, struct inode *inode) |
2762 | { |
2763 | int error; |
2764 | |
2765 | if (S_ISBLK(inode->i_mode)) { |
2766 | p->bdev_handle = bdev_open_by_dev(dev: inode->i_rdev, |
2767 | BLK_OPEN_READ | BLK_OPEN_WRITE, holder: p, NULL); |
2768 | if (IS_ERR(ptr: p->bdev_handle)) { |
2769 | error = PTR_ERR(ptr: p->bdev_handle); |
2770 | p->bdev_handle = NULL; |
2771 | return error; |
2772 | } |
2773 | p->bdev = p->bdev_handle->bdev; |
2774 | p->old_block_size = block_size(bdev: p->bdev); |
2775 | error = set_blocksize(bdev: p->bdev, PAGE_SIZE); |
2776 | if (error < 0) |
2777 | return error; |
2778 | /* |
2779 | * Zoned block devices contain zones that have a sequential |
2780 | * write only restriction. Hence zoned block devices are not |
2781 | * suitable for swapping. Disallow them here. |
2782 | */ |
2783 | if (bdev_is_zoned(bdev: p->bdev)) |
2784 | return -EINVAL; |
2785 | p->flags |= SWP_BLKDEV; |
2786 | } else if (S_ISREG(inode->i_mode)) { |
2787 | p->bdev = inode->i_sb->s_bdev; |
2788 | } |
2789 | |
2790 | return 0; |
2791 | } |
2792 | |
2793 | |
2794 | /* |
2795 | * Find out how many pages are allowed for a single swap device. There |
2796 | * are two limiting factors: |
2797 | * 1) the number of bits for the swap offset in the swp_entry_t type, and |
2798 | * 2) the number of bits in the swap pte, as defined by the different |
2799 | * architectures. |
2800 | * |
2801 | * In order to find the largest possible bit mask, a swap entry with |
2802 | * swap type 0 and swap offset ~0UL is created, encoded to a swap pte, |
2803 | * decoded to a swp_entry_t again, and finally the swap offset is |
2804 | * extracted. |
2805 | * |
2806 | * This will mask all the bits from the initial ~0UL mask that can't |
2807 | * be encoded in either the swp_entry_t or the architecture definition |
2808 | * of a swap pte. |
2809 | */ |
2810 | unsigned long generic_max_swapfile_size(void) |
2811 | { |
2812 | return swp_offset(entry: pte_to_swp_entry( |
2813 | pte: swp_entry_to_pte(entry: swp_entry(type: 0, offset: ~0UL)))) + 1; |
2814 | } |
2815 | |
2816 | /* Can be overridden by an architecture for additional checks. */ |
2817 | __weak unsigned long arch_max_swapfile_size(void) |
2818 | { |
2819 | return generic_max_swapfile_size(); |
2820 | } |
2821 | |
2822 | static unsigned long (struct swap_info_struct *p, |
2823 | union swap_header *, |
2824 | struct inode *inode) |
2825 | { |
2826 | int i; |
2827 | unsigned long maxpages; |
2828 | unsigned long swapfilepages; |
2829 | unsigned long last_page; |
2830 | |
2831 | if (memcmp(p: "SWAPSPACE2" , q: swap_header->magic.magic, size: 10)) { |
2832 | pr_err("Unable to find swap-space signature\n" ); |
2833 | return 0; |
2834 | } |
2835 | |
2836 | /* swap partition endianness hack... */ |
2837 | if (swab32(swap_header->info.version) == 1) { |
2838 | swab32s(p: &swap_header->info.version); |
2839 | swab32s(p: &swap_header->info.last_page); |
2840 | swab32s(p: &swap_header->info.nr_badpages); |
2841 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
2842 | return 0; |
2843 | for (i = 0; i < swap_header->info.nr_badpages; i++) |
2844 | swab32s(p: &swap_header->info.badpages[i]); |
2845 | } |
2846 | /* Check the swap header's sub-version */ |
2847 | if (swap_header->info.version != 1) { |
2848 | pr_warn("Unable to handle swap header version %d\n" , |
2849 | swap_header->info.version); |
2850 | return 0; |
2851 | } |
2852 | |
2853 | p->lowest_bit = 1; |
2854 | p->cluster_next = 1; |
2855 | p->cluster_nr = 0; |
2856 | |
2857 | maxpages = swapfile_maximum_size; |
2858 | last_page = swap_header->info.last_page; |
2859 | if (!last_page) { |
2860 | pr_warn("Empty swap-file\n" ); |
2861 | return 0; |
2862 | } |
2863 | if (last_page > maxpages) { |
2864 | pr_warn("Truncating oversized swap area, only using %luk out of %luk\n" , |
2865 | K(maxpages), K(last_page)); |
2866 | } |
2867 | if (maxpages > last_page) { |
2868 | maxpages = last_page + 1; |
2869 | /* p->max is an unsigned int: don't overflow it */ |
2870 | if ((unsigned int)maxpages == 0) |
2871 | maxpages = UINT_MAX; |
2872 | } |
2873 | p->highest_bit = maxpages - 1; |
2874 | |
2875 | if (!maxpages) |
2876 | return 0; |
2877 | swapfilepages = i_size_read(inode) >> PAGE_SHIFT; |
2878 | if (swapfilepages && maxpages > swapfilepages) { |
2879 | pr_warn("Swap area shorter than signature indicates\n" ); |
2880 | return 0; |
2881 | } |
2882 | if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) |
2883 | return 0; |
2884 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
2885 | return 0; |
2886 | |
2887 | return maxpages; |
2888 | } |
2889 | |
2890 | #define SWAP_CLUSTER_INFO_COLS \ |
2891 | DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info)) |
2892 | #define SWAP_CLUSTER_SPACE_COLS \ |
2893 | DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER) |
2894 | #define SWAP_CLUSTER_COLS \ |
2895 | max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS) |
2896 | |
2897 | static int setup_swap_map_and_extents(struct swap_info_struct *p, |
2898 | union swap_header *, |
2899 | unsigned char *swap_map, |
2900 | struct swap_cluster_info *cluster_info, |
2901 | unsigned long maxpages, |
2902 | sector_t *span) |
2903 | { |
2904 | unsigned int j, k; |
2905 | unsigned int nr_good_pages; |
2906 | int nr_extents; |
2907 | unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); |
2908 | unsigned long col = p->cluster_next / SWAPFILE_CLUSTER % SWAP_CLUSTER_COLS; |
2909 | unsigned long i, idx; |
2910 | |
2911 | nr_good_pages = maxpages - 1; /* omit header page */ |
2912 | |
2913 | cluster_list_init(list: &p->free_clusters); |
2914 | cluster_list_init(list: &p->discard_clusters); |
2915 | |
2916 | for (i = 0; i < swap_header->info.nr_badpages; i++) { |
2917 | unsigned int page_nr = swap_header->info.badpages[i]; |
2918 | if (page_nr == 0 || page_nr > swap_header->info.last_page) |
2919 | return -EINVAL; |
2920 | if (page_nr < maxpages) { |
2921 | swap_map[page_nr] = SWAP_MAP_BAD; |
2922 | nr_good_pages--; |
2923 | /* |
2924 | * Haven't marked the cluster free yet, no list |
2925 | * operation involved |
2926 | */ |
2927 | inc_cluster_info_page(p, cluster_info, page_nr); |
2928 | } |
2929 | } |
2930 | |
2931 | /* Haven't marked the cluster free yet, no list operation involved */ |
2932 | for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++) |
2933 | inc_cluster_info_page(p, cluster_info, page_nr: i); |
2934 | |
2935 | if (nr_good_pages) { |
2936 | swap_map[0] = SWAP_MAP_BAD; |
2937 | /* |
2938 | * Not mark the cluster free yet, no list |
2939 | * operation involved |
2940 | */ |
2941 | inc_cluster_info_page(p, cluster_info, page_nr: 0); |
2942 | p->max = maxpages; |
2943 | p->pages = nr_good_pages; |
2944 | nr_extents = setup_swap_extents(sis: p, span); |
2945 | if (nr_extents < 0) |
2946 | return nr_extents; |
2947 | nr_good_pages = p->pages; |
2948 | } |
2949 | if (!nr_good_pages) { |
2950 | pr_warn("Empty swap-file\n" ); |
2951 | return -EINVAL; |
2952 | } |
2953 | |
2954 | if (!cluster_info) |
2955 | return nr_extents; |
2956 | |
2957 | |
2958 | /* |
2959 | * Reduce false cache line sharing between cluster_info and |
2960 | * sharing same address space. |
2961 | */ |
2962 | for (k = 0; k < SWAP_CLUSTER_COLS; k++) { |
2963 | j = (k + col) % SWAP_CLUSTER_COLS; |
2964 | for (i = 0; i < DIV_ROUND_UP(nr_clusters, SWAP_CLUSTER_COLS); i++) { |
2965 | idx = i * SWAP_CLUSTER_COLS + j; |
2966 | if (idx >= nr_clusters) |
2967 | continue; |
2968 | if (cluster_count(info: &cluster_info[idx])) |
2969 | continue; |
2970 | cluster_set_flag(info: &cluster_info[idx], CLUSTER_FLAG_FREE); |
2971 | cluster_list_add_tail(list: &p->free_clusters, ci: cluster_info, |
2972 | idx); |
2973 | } |
2974 | } |
2975 | return nr_extents; |
2976 | } |
2977 | |
2978 | SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) |
2979 | { |
2980 | struct swap_info_struct *p; |
2981 | struct filename *name; |
2982 | struct file *swap_file = NULL; |
2983 | struct address_space *mapping; |
2984 | struct dentry *dentry; |
2985 | int prio; |
2986 | int error; |
2987 | union swap_header *; |
2988 | int nr_extents; |
2989 | sector_t span; |
2990 | unsigned long maxpages; |
2991 | unsigned char *swap_map = NULL; |
2992 | struct swap_cluster_info *cluster_info = NULL; |
2993 | struct page *page = NULL; |
2994 | struct inode *inode = NULL; |
2995 | bool inced_nr_rotate_swap = false; |
2996 | |
2997 | if (swap_flags & ~SWAP_FLAGS_VALID) |
2998 | return -EINVAL; |
2999 | |
3000 | if (!capable(CAP_SYS_ADMIN)) |
3001 | return -EPERM; |
3002 | |
3003 | if (!swap_avail_heads) |
3004 | return -ENOMEM; |
3005 | |
3006 | p = alloc_swap_info(); |
3007 | if (IS_ERR(ptr: p)) |
3008 | return PTR_ERR(ptr: p); |
3009 | |
3010 | INIT_WORK(&p->discard_work, swap_discard_work); |
3011 | |
3012 | name = getname(specialfile); |
3013 | if (IS_ERR(ptr: name)) { |
3014 | error = PTR_ERR(ptr: name); |
3015 | name = NULL; |
3016 | goto bad_swap; |
3017 | } |
3018 | swap_file = file_open_name(name, O_RDWR|O_LARGEFILE, 0); |
3019 | if (IS_ERR(ptr: swap_file)) { |
3020 | error = PTR_ERR(ptr: swap_file); |
3021 | swap_file = NULL; |
3022 | goto bad_swap; |
3023 | } |
3024 | |
3025 | p->swap_file = swap_file; |
3026 | mapping = swap_file->f_mapping; |
3027 | dentry = swap_file->f_path.dentry; |
3028 | inode = mapping->host; |
3029 | |
3030 | error = claim_swapfile(p, inode); |
3031 | if (unlikely(error)) |
3032 | goto bad_swap; |
3033 | |
3034 | inode_lock(inode); |
3035 | if (d_unlinked(dentry) || cant_mount(dentry)) { |
3036 | error = -ENOENT; |
3037 | goto bad_swap_unlock_inode; |
3038 | } |
3039 | if (IS_SWAPFILE(inode)) { |
3040 | error = -EBUSY; |
3041 | goto bad_swap_unlock_inode; |
3042 | } |
3043 | |
3044 | /* |
3045 | * Read the swap header. |
3046 | */ |
3047 | if (!mapping->a_ops->read_folio) { |
3048 | error = -EINVAL; |
3049 | goto bad_swap_unlock_inode; |
3050 | } |
3051 | page = read_mapping_page(mapping, index: 0, file: swap_file); |
3052 | if (IS_ERR(ptr: page)) { |
3053 | error = PTR_ERR(ptr: page); |
3054 | goto bad_swap_unlock_inode; |
3055 | } |
3056 | swap_header = kmap(page); |
3057 | |
3058 | maxpages = read_swap_header(p, swap_header, inode); |
3059 | if (unlikely(!maxpages)) { |
3060 | error = -EINVAL; |
3061 | goto bad_swap_unlock_inode; |
3062 | } |
3063 | |
3064 | /* OK, set up the swap map and apply the bad block list */ |
3065 | swap_map = vzalloc(size: maxpages); |
3066 | if (!swap_map) { |
3067 | error = -ENOMEM; |
3068 | goto bad_swap_unlock_inode; |
3069 | } |
3070 | |
3071 | if (p->bdev && bdev_stable_writes(bdev: p->bdev)) |
3072 | p->flags |= SWP_STABLE_WRITES; |
3073 | |
3074 | if (p->bdev && bdev_synchronous(bdev: p->bdev)) |
3075 | p->flags |= SWP_SYNCHRONOUS_IO; |
3076 | |
3077 | if (p->bdev && bdev_nonrot(bdev: p->bdev)) { |
3078 | int cpu; |
3079 | unsigned long ci, nr_cluster; |
3080 | |
3081 | p->flags |= SWP_SOLIDSTATE; |
3082 | p->cluster_next_cpu = alloc_percpu(unsigned int); |
3083 | if (!p->cluster_next_cpu) { |
3084 | error = -ENOMEM; |
3085 | goto bad_swap_unlock_inode; |
3086 | } |
3087 | /* |
3088 | * select a random position to start with to help wear leveling |
3089 | * SSD |
3090 | */ |
3091 | for_each_possible_cpu(cpu) { |
3092 | per_cpu(*p->cluster_next_cpu, cpu) = |
3093 | get_random_u32_inclusive(floor: 1, ceil: p->highest_bit); |
3094 | } |
3095 | nr_cluster = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); |
3096 | |
3097 | cluster_info = kvcalloc(n: nr_cluster, size: sizeof(*cluster_info), |
3098 | GFP_KERNEL); |
3099 | if (!cluster_info) { |
3100 | error = -ENOMEM; |
3101 | goto bad_swap_unlock_inode; |
3102 | } |
3103 | |
3104 | for (ci = 0; ci < nr_cluster; ci++) |
3105 | spin_lock_init(&((cluster_info + ci)->lock)); |
3106 | |
3107 | p->percpu_cluster = alloc_percpu(struct percpu_cluster); |
3108 | if (!p->percpu_cluster) { |
3109 | error = -ENOMEM; |
3110 | goto bad_swap_unlock_inode; |
3111 | } |
3112 | for_each_possible_cpu(cpu) { |
3113 | struct percpu_cluster *cluster; |
3114 | cluster = per_cpu_ptr(p->percpu_cluster, cpu); |
3115 | cluster_set_null(info: &cluster->index); |
3116 | } |
3117 | } else { |
3118 | atomic_inc(v: &nr_rotate_swap); |
3119 | inced_nr_rotate_swap = true; |
3120 | } |
3121 | |
3122 | error = swap_cgroup_swapon(type: p->type, max_pages: maxpages); |
3123 | if (error) |
3124 | goto bad_swap_unlock_inode; |
3125 | |
3126 | nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map, |
3127 | cluster_info, maxpages, span: &span); |
3128 | if (unlikely(nr_extents < 0)) { |
3129 | error = nr_extents; |
3130 | goto bad_swap_unlock_inode; |
3131 | } |
3132 | |
3133 | if ((swap_flags & SWAP_FLAG_DISCARD) && |
3134 | p->bdev && bdev_max_discard_sectors(bdev: p->bdev)) { |
3135 | /* |
3136 | * When discard is enabled for swap with no particular |
3137 | * policy flagged, we set all swap discard flags here in |
3138 | * order to sustain backward compatibility with older |
3139 | * swapon(8) releases. |
3140 | */ |
3141 | p->flags |= (SWP_DISCARDABLE | SWP_AREA_DISCARD | |
3142 | SWP_PAGE_DISCARD); |
3143 | |
3144 | /* |
3145 | * By flagging sys_swapon, a sysadmin can tell us to |
3146 | * either do single-time area discards only, or to just |
3147 | * perform discards for released swap page-clusters. |
3148 | * Now it's time to adjust the p->flags accordingly. |
3149 | */ |
3150 | if (swap_flags & SWAP_FLAG_DISCARD_ONCE) |
3151 | p->flags &= ~SWP_PAGE_DISCARD; |
3152 | else if (swap_flags & SWAP_FLAG_DISCARD_PAGES) |
3153 | p->flags &= ~SWP_AREA_DISCARD; |
3154 | |
3155 | /* issue a swapon-time discard if it's still required */ |
3156 | if (p->flags & SWP_AREA_DISCARD) { |
3157 | int err = discard_swap(si: p); |
3158 | if (unlikely(err)) |
3159 | pr_err("swapon: discard_swap(%p): %d\n" , |
3160 | p, err); |
3161 | } |
3162 | } |
3163 | |
3164 | error = init_swap_address_space(type: p->type, nr_pages: maxpages); |
3165 | if (error) |
3166 | goto bad_swap_unlock_inode; |
3167 | |
3168 | /* |
3169 | * Flush any pending IO and dirty mappings before we start using this |
3170 | * swap device. |
3171 | */ |
3172 | inode->i_flags |= S_SWAPFILE; |
3173 | error = inode_drain_writes(inode); |
3174 | if (error) { |
3175 | inode->i_flags &= ~S_SWAPFILE; |
3176 | goto free_swap_address_space; |
3177 | } |
3178 | |
3179 | mutex_lock(&swapon_mutex); |
3180 | prio = -1; |
3181 | if (swap_flags & SWAP_FLAG_PREFER) |
3182 | prio = |
3183 | (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT; |
3184 | enable_swap_info(p, prio, swap_map, cluster_info); |
3185 | |
3186 | pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s\n" , |
3187 | K(p->pages), name->name, p->prio, nr_extents, |
3188 | K((unsigned long long)span), |
3189 | (p->flags & SWP_SOLIDSTATE) ? "SS" : "" , |
3190 | (p->flags & SWP_DISCARDABLE) ? "D" : "" , |
3191 | (p->flags & SWP_AREA_DISCARD) ? "s" : "" , |
3192 | (p->flags & SWP_PAGE_DISCARD) ? "c" : "" ); |
3193 | |
3194 | mutex_unlock(lock: &swapon_mutex); |
3195 | atomic_inc(v: &proc_poll_event); |
3196 | wake_up_interruptible(&proc_poll_wait); |
3197 | |
3198 | error = 0; |
3199 | goto out; |
3200 | free_swap_address_space: |
3201 | exit_swap_address_space(type: p->type); |
3202 | bad_swap_unlock_inode: |
3203 | inode_unlock(inode); |
3204 | bad_swap: |
3205 | free_percpu(pdata: p->percpu_cluster); |
3206 | p->percpu_cluster = NULL; |
3207 | free_percpu(pdata: p->cluster_next_cpu); |
3208 | p->cluster_next_cpu = NULL; |
3209 | if (p->bdev_handle) { |
3210 | set_blocksize(bdev: p->bdev, size: p->old_block_size); |
3211 | bdev_release(handle: p->bdev_handle); |
3212 | p->bdev_handle = NULL; |
3213 | } |
3214 | inode = NULL; |
3215 | destroy_swap_extents(sis: p); |
3216 | swap_cgroup_swapoff(type: p->type); |
3217 | spin_lock(lock: &swap_lock); |
3218 | p->swap_file = NULL; |
3219 | p->flags = 0; |
3220 | spin_unlock(lock: &swap_lock); |
3221 | vfree(addr: swap_map); |
3222 | kvfree(addr: cluster_info); |
3223 | if (inced_nr_rotate_swap) |
3224 | atomic_dec(v: &nr_rotate_swap); |
3225 | if (swap_file) |
3226 | filp_close(swap_file, NULL); |
3227 | out: |
3228 | if (page && !IS_ERR(ptr: page)) { |
3229 | kunmap(page); |
3230 | put_page(page); |
3231 | } |
3232 | if (name) |
3233 | putname(name); |
3234 | if (inode) |
3235 | inode_unlock(inode); |
3236 | if (!error) |
3237 | enable_swap_slots_cache(); |
3238 | return error; |
3239 | } |
3240 | |
3241 | void si_swapinfo(struct sysinfo *val) |
3242 | { |
3243 | unsigned int type; |
3244 | unsigned long nr_to_be_unused = 0; |
3245 | |
3246 | spin_lock(lock: &swap_lock); |
3247 | for (type = 0; type < nr_swapfiles; type++) { |
3248 | struct swap_info_struct *si = swap_info[type]; |
3249 | |
3250 | if ((si->flags & SWP_USED) && !(si->flags & SWP_WRITEOK)) |
3251 | nr_to_be_unused += READ_ONCE(si->inuse_pages); |
3252 | } |
3253 | val->freeswap = atomic_long_read(v: &nr_swap_pages) + nr_to_be_unused; |
3254 | val->totalswap = total_swap_pages + nr_to_be_unused; |
3255 | spin_unlock(lock: &swap_lock); |
3256 | } |
3257 | |
3258 | /* |
3259 | * Verify that a swap entry is valid and increment its swap map count. |
3260 | * |
3261 | * Returns error code in following case. |
3262 | * - success -> 0 |
3263 | * - swp_entry is invalid -> EINVAL |
3264 | * - swp_entry is migration entry -> EINVAL |
3265 | * - swap-cache reference is requested but there is already one. -> EEXIST |
3266 | * - swap-cache reference is requested but the entry is not used. -> ENOENT |
3267 | * - swap-mapped reference requested but needs continued swap count. -> ENOMEM |
3268 | */ |
3269 | static int __swap_duplicate(swp_entry_t entry, unsigned char usage) |
3270 | { |
3271 | struct swap_info_struct *p; |
3272 | struct swap_cluster_info *ci; |
3273 | unsigned long offset; |
3274 | unsigned char count; |
3275 | unsigned char has_cache; |
3276 | int err; |
3277 | |
3278 | p = swp_swap_info(entry); |
3279 | |
3280 | offset = swp_offset(entry); |
3281 | ci = lock_cluster_or_swap_info(si: p, offset); |
3282 | |
3283 | count = p->swap_map[offset]; |
3284 | |
3285 | /* |
3286 | * swapin_readahead() doesn't check if a swap entry is valid, so the |
3287 | * swap entry could be SWAP_MAP_BAD. Check here with lock held. |
3288 | */ |
3289 | if (unlikely(swap_count(count) == SWAP_MAP_BAD)) { |
3290 | err = -ENOENT; |
3291 | goto unlock_out; |
3292 | } |
3293 | |
3294 | has_cache = count & SWAP_HAS_CACHE; |
3295 | count &= ~SWAP_HAS_CACHE; |
3296 | err = 0; |
3297 | |
3298 | if (usage == SWAP_HAS_CACHE) { |
3299 | |
3300 | /* set SWAP_HAS_CACHE if there is no cache and entry is used */ |
3301 | if (!has_cache && count) |
3302 | has_cache = SWAP_HAS_CACHE; |
3303 | else if (has_cache) /* someone else added cache */ |
3304 | err = -EEXIST; |
3305 | else /* no users remaining */ |
3306 | err = -ENOENT; |
3307 | |
3308 | } else if (count || has_cache) { |
3309 | |
3310 | if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX) |
3311 | count += usage; |
3312 | else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX) |
3313 | err = -EINVAL; |
3314 | else if (swap_count_continued(p, offset, count)) |
3315 | count = COUNT_CONTINUED; |
3316 | else |
3317 | err = -ENOMEM; |
3318 | } else |
3319 | err = -ENOENT; /* unused swap entry */ |
3320 | |
3321 | WRITE_ONCE(p->swap_map[offset], count | has_cache); |
3322 | |
3323 | unlock_out: |
3324 | unlock_cluster_or_swap_info(si: p, ci); |
3325 | return err; |
3326 | } |
3327 | |
3328 | /* |
3329 | * Help swapoff by noting that swap entry belongs to shmem/tmpfs |
3330 | * (in which case its reference count is never incremented). |
3331 | */ |
3332 | void swap_shmem_alloc(swp_entry_t entry) |
3333 | { |
3334 | __swap_duplicate(entry, SWAP_MAP_SHMEM); |
3335 | } |
3336 | |
3337 | /* |
3338 | * Increase reference count of swap entry by 1. |
3339 | * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required |
3340 | * but could not be atomically allocated. Returns 0, just as if it succeeded, |
3341 | * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which |
3342 | * might occur if a page table entry has got corrupted. |
3343 | */ |
3344 | int swap_duplicate(swp_entry_t entry) |
3345 | { |
3346 | int err = 0; |
3347 | |
3348 | while (!err && __swap_duplicate(entry, usage: 1) == -ENOMEM) |
3349 | err = add_swap_count_continuation(entry, GFP_ATOMIC); |
3350 | return err; |
3351 | } |
3352 | |
3353 | /* |
3354 | * @entry: swap entry for which we allocate swap cache. |
3355 | * |
3356 | * Called when allocating swap cache for existing swap entry, |
3357 | * This can return error codes. Returns 0 at success. |
3358 | * -EEXIST means there is a swap cache. |
3359 | * Note: return code is different from swap_duplicate(). |
3360 | */ |
3361 | int swapcache_prepare(swp_entry_t entry) |
3362 | { |
3363 | return __swap_duplicate(entry, SWAP_HAS_CACHE); |
3364 | } |
3365 | |
3366 | struct swap_info_struct *swp_swap_info(swp_entry_t entry) |
3367 | { |
3368 | return swap_type_to_swap_info(type: swp_type(entry)); |
3369 | } |
3370 | |
3371 | struct swap_info_struct *page_swap_info(struct page *page) |
3372 | { |
3373 | swp_entry_t entry = page_swap_entry(page); |
3374 | return swp_swap_info(entry); |
3375 | } |
3376 | |
3377 | /* |
3378 | * out-of-line methods to avoid include hell. |
3379 | */ |
3380 | struct address_space *swapcache_mapping(struct folio *folio) |
3381 | { |
3382 | return page_swap_info(page: &folio->page)->swap_file->f_mapping; |
3383 | } |
3384 | EXPORT_SYMBOL_GPL(swapcache_mapping); |
3385 | |
3386 | pgoff_t __page_file_index(struct page *page) |
3387 | { |
3388 | swp_entry_t swap = page_swap_entry(page); |
3389 | return swp_offset(entry: swap); |
3390 | } |
3391 | EXPORT_SYMBOL_GPL(__page_file_index); |
3392 | |
3393 | /* |
3394 | * add_swap_count_continuation - called when a swap count is duplicated |
3395 | * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's |
3396 | * page of the original vmalloc'ed swap_map, to hold the continuation count |
3397 | * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called |
3398 | * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc. |
3399 | * |
3400 | * These continuation pages are seldom referenced: the common paths all work |
3401 | * on the original swap_map, only referring to a continuation page when the |
3402 | * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX. |
3403 | * |
3404 | * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding |
3405 | * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL) |
3406 | * can be called after dropping locks. |
3407 | */ |
3408 | int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask) |
3409 | { |
3410 | struct swap_info_struct *si; |
3411 | struct swap_cluster_info *ci; |
3412 | struct page *head; |
3413 | struct page *page; |
3414 | struct page *list_page; |
3415 | pgoff_t offset; |
3416 | unsigned char count; |
3417 | int ret = 0; |
3418 | |
3419 | /* |
3420 | * When debugging, it's easier to use __GFP_ZERO here; but it's better |
3421 | * for latency not to zero a page while GFP_ATOMIC and holding locks. |
3422 | */ |
3423 | page = alloc_page(gfp_mask | __GFP_HIGHMEM); |
3424 | |
3425 | si = get_swap_device(entry); |
3426 | if (!si) { |
3427 | /* |
3428 | * An acceptable race has occurred since the failing |
3429 | * __swap_duplicate(): the swap device may be swapoff |
3430 | */ |
3431 | goto outer; |
3432 | } |
3433 | spin_lock(lock: &si->lock); |
3434 | |
3435 | offset = swp_offset(entry); |
3436 | |
3437 | ci = lock_cluster(si, offset); |
3438 | |
3439 | count = swap_count(ent: si->swap_map[offset]); |
3440 | |
3441 | if ((count & ~COUNT_CONTINUED) != SWAP_MAP_MAX) { |
3442 | /* |
3443 | * The higher the swap count, the more likely it is that tasks |
3444 | * will race to add swap count continuation: we need to avoid |
3445 | * over-provisioning. |
3446 | */ |
3447 | goto out; |
3448 | } |
3449 | |
3450 | if (!page) { |
3451 | ret = -ENOMEM; |
3452 | goto out; |
3453 | } |
3454 | |
3455 | head = vmalloc_to_page(addr: si->swap_map + offset); |
3456 | offset &= ~PAGE_MASK; |
3457 | |
3458 | spin_lock(lock: &si->cont_lock); |
3459 | /* |
3460 | * Page allocation does not initialize the page's lru field, |
3461 | * but it does always reset its private field. |
3462 | */ |
3463 | if (!page_private(head)) { |
3464 | BUG_ON(count & COUNT_CONTINUED); |
3465 | INIT_LIST_HEAD(list: &head->lru); |
3466 | set_page_private(page: head, private: SWP_CONTINUED); |
3467 | si->flags |= SWP_CONTINUED; |
3468 | } |
3469 | |
3470 | list_for_each_entry(list_page, &head->lru, lru) { |
3471 | unsigned char *map; |
3472 | |
3473 | /* |
3474 | * If the previous map said no continuation, but we've found |
3475 | * a continuation page, free our allocation and use this one. |
3476 | */ |
3477 | if (!(count & COUNT_CONTINUED)) |
3478 | goto out_unlock_cont; |
3479 | |
3480 | map = kmap_atomic(page: list_page) + offset; |
3481 | count = *map; |
3482 | kunmap_atomic(map); |
3483 | |
3484 | /* |
3485 | * If this continuation count now has some space in it, |
3486 | * free our allocation and use this one. |
3487 | */ |
3488 | if ((count & ~COUNT_CONTINUED) != SWAP_CONT_MAX) |
3489 | goto out_unlock_cont; |
3490 | } |
3491 | |
3492 | list_add_tail(new: &page->lru, head: &head->lru); |
3493 | page = NULL; /* now it's attached, don't free it */ |
3494 | out_unlock_cont: |
3495 | spin_unlock(lock: &si->cont_lock); |
3496 | out: |
3497 | unlock_cluster(ci); |
3498 | spin_unlock(lock: &si->lock); |
3499 | put_swap_device(si); |
3500 | outer: |
3501 | if (page) |
3502 | __free_page(page); |
3503 | return ret; |
3504 | } |
3505 | |
3506 | /* |
3507 | * swap_count_continued - when the original swap_map count is incremented |
3508 | * from SWAP_MAP_MAX, check if there is already a continuation page to carry |
3509 | * into, carry if so, or else fail until a new continuation page is allocated; |
3510 | * when the original swap_map count is decremented from 0 with continuation, |
3511 | * borrow from the continuation and report whether it still holds more. |
3512 | * Called while __swap_duplicate() or swap_entry_free() holds swap or cluster |
3513 | * lock. |
3514 | */ |
3515 | static bool swap_count_continued(struct swap_info_struct *si, |
3516 | pgoff_t offset, unsigned char count) |
3517 | { |
3518 | struct page *head; |
3519 | struct page *page; |
3520 | unsigned char *map; |
3521 | bool ret; |
3522 | |
3523 | head = vmalloc_to_page(addr: si->swap_map + offset); |
3524 | if (page_private(head) != SWP_CONTINUED) { |
3525 | BUG_ON(count & COUNT_CONTINUED); |
3526 | return false; /* need to add count continuation */ |
3527 | } |
3528 | |
3529 | spin_lock(lock: &si->cont_lock); |
3530 | offset &= ~PAGE_MASK; |
3531 | page = list_next_entry(head, lru); |
3532 | map = kmap_atomic(page) + offset; |
3533 | |
3534 | if (count == SWAP_MAP_MAX) /* initial increment from swap_map */ |
3535 | goto init_map; /* jump over SWAP_CONT_MAX checks */ |
3536 | |
3537 | if (count == (SWAP_MAP_MAX | COUNT_CONTINUED)) { /* incrementing */ |
3538 | /* |
3539 | * Think of how you add 1 to 999 |
3540 | */ |
3541 | while (*map == (SWAP_CONT_MAX | COUNT_CONTINUED)) { |
3542 | kunmap_atomic(map); |
3543 | page = list_next_entry(page, lru); |
3544 | BUG_ON(page == head); |
3545 | map = kmap_atomic(page) + offset; |
3546 | } |
3547 | if (*map == SWAP_CONT_MAX) { |
3548 | kunmap_atomic(map); |
3549 | page = list_next_entry(page, lru); |
3550 | if (page == head) { |
3551 | ret = false; /* add count continuation */ |
3552 | goto out; |
3553 | } |
3554 | map = kmap_atomic(page) + offset; |
3555 | init_map: *map = 0; /* we didn't zero the page */ |
3556 | } |
3557 | *map += 1; |
3558 | kunmap_atomic(map); |
3559 | while ((page = list_prev_entry(page, lru)) != head) { |
3560 | map = kmap_atomic(page) + offset; |
3561 | *map = COUNT_CONTINUED; |
3562 | kunmap_atomic(map); |
3563 | } |
3564 | ret = true; /* incremented */ |
3565 | |
3566 | } else { /* decrementing */ |
3567 | /* |
3568 | * Think of how you subtract 1 from 1000 |
3569 | */ |
3570 | BUG_ON(count != COUNT_CONTINUED); |
3571 | while (*map == COUNT_CONTINUED) { |
3572 | kunmap_atomic(map); |
3573 | page = list_next_entry(page, lru); |
3574 | BUG_ON(page == head); |
3575 | map = kmap_atomic(page) + offset; |
3576 | } |
3577 | BUG_ON(*map == 0); |
3578 | *map -= 1; |
3579 | if (*map == 0) |
3580 | count = 0; |
3581 | kunmap_atomic(map); |
3582 | while ((page = list_prev_entry(page, lru)) != head) { |
3583 | map = kmap_atomic(page) + offset; |
3584 | *map = SWAP_CONT_MAX | count; |
3585 | count = COUNT_CONTINUED; |
3586 | kunmap_atomic(map); |
3587 | } |
3588 | ret = count == COUNT_CONTINUED; |
3589 | } |
3590 | out: |
3591 | spin_unlock(lock: &si->cont_lock); |
3592 | return ret; |
3593 | } |
3594 | |
3595 | /* |
3596 | * free_swap_count_continuations - swapoff free all the continuation pages |
3597 | * appended to the swap_map, after swap_map is quiesced, before vfree'ing it. |
3598 | */ |
3599 | static void free_swap_count_continuations(struct swap_info_struct *si) |
3600 | { |
3601 | pgoff_t offset; |
3602 | |
3603 | for (offset = 0; offset < si->max; offset += PAGE_SIZE) { |
3604 | struct page *head; |
3605 | head = vmalloc_to_page(addr: si->swap_map + offset); |
3606 | if (page_private(head)) { |
3607 | struct page *page, *next; |
3608 | |
3609 | list_for_each_entry_safe(page, next, &head->lru, lru) { |
3610 | list_del(entry: &page->lru); |
3611 | __free_page(page); |
3612 | } |
3613 | } |
3614 | } |
3615 | } |
3616 | |
3617 | #if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP) |
3618 | void __folio_throttle_swaprate(struct folio *folio, gfp_t gfp) |
3619 | { |
3620 | struct swap_info_struct *si, *next; |
3621 | int nid = folio_nid(folio); |
3622 | |
3623 | if (!(gfp & __GFP_IO)) |
3624 | return; |
3625 | |
3626 | if (!blk_cgroup_congested()) |
3627 | return; |
3628 | |
3629 | /* |
3630 | * We've already scheduled a throttle, avoid taking the global swap |
3631 | * lock. |
3632 | */ |
3633 | if (current->throttle_disk) |
3634 | return; |
3635 | |
3636 | spin_lock(lock: &swap_avail_lock); |
3637 | plist_for_each_entry_safe(si, next, &swap_avail_heads[nid], |
3638 | avail_lists[nid]) { |
3639 | if (si->bdev) { |
3640 | blkcg_schedule_throttle(disk: si->bdev->bd_disk, use_memdelay: true); |
3641 | break; |
3642 | } |
3643 | } |
3644 | spin_unlock(lock: &swap_avail_lock); |
3645 | } |
3646 | #endif |
3647 | |
3648 | static int __init swapfile_init(void) |
3649 | { |
3650 | int nid; |
3651 | |
3652 | swap_avail_heads = kmalloc_array(n: nr_node_ids, size: sizeof(struct plist_head), |
3653 | GFP_KERNEL); |
3654 | if (!swap_avail_heads) { |
3655 | pr_emerg("Not enough memory for swap heads, swap is disabled\n" ); |
3656 | return -ENOMEM; |
3657 | } |
3658 | |
3659 | for_each_node(nid) |
3660 | plist_head_init(head: &swap_avail_heads[nid]); |
3661 | |
3662 | swapfile_maximum_size = arch_max_swapfile_size(); |
3663 | |
3664 | #ifdef CONFIG_MIGRATION |
3665 | if (swapfile_maximum_size >= (1UL << SWP_MIG_TOTAL_BITS)) |
3666 | swap_migration_ad_supported = true; |
3667 | #endif /* CONFIG_MIGRATION */ |
3668 | |
3669 | return 0; |
3670 | } |
3671 | subsys_initcall(swapfile_init); |
3672 | |