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