1 | /* |
2 | * linux/mm/swapfile.c |
3 | * |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds |
5 | * Swap reorganised 29.12.95, Stephen Tweedie |
6 | */ |
7 | |
8 | #include <linux/mm.h> |
9 | #include <linux/sched/mm.h> |
10 | #include <linux/sched/task.h> |
11 | #include <linux/hugetlb.h> |
12 | #include <linux/mman.h> |
13 | #include <linux/slab.h> |
14 | #include <linux/kernel_stat.h> |
15 | #include <linux/swap.h> |
16 | #include <linux/vmalloc.h> |
17 | #include <linux/pagemap.h> |
18 | #include <linux/namei.h> |
19 | #include <linux/shmem_fs.h> |
20 | #include <linux/blkdev.h> |
21 | #include <linux/random.h> |
22 | #include <linux/writeback.h> |
23 | #include <linux/proc_fs.h> |
24 | #include <linux/seq_file.h> |
25 | #include <linux/init.h> |
26 | #include <linux/ksm.h> |
27 | #include <linux/rmap.h> |
28 | #include <linux/security.h> |
29 | #include <linux/backing-dev.h> |
30 | #include <linux/mutex.h> |
31 | #include <linux/capability.h> |
32 | #include <linux/syscalls.h> |
33 | #include <linux/memcontrol.h> |
34 | #include <linux/poll.h> |
35 | #include <linux/oom.h> |
36 | #include <linux/frontswap.h> |
37 | #include <linux/swapfile.h> |
38 | #include <linux/export.h> |
39 | #include <linux/swap_slots.h> |
40 | #include <linux/sort.h> |
41 | |
42 | #include <asm/pgtable.h> |
43 | #include <asm/tlbflush.h> |
44 | #include <linux/swapops.h> |
45 | #include <linux/swap_cgroup.h> |
46 | |
47 | static bool swap_count_continued(struct swap_info_struct *, pgoff_t, |
48 | unsigned char); |
49 | static void free_swap_count_continuations(struct swap_info_struct *); |
50 | static sector_t map_swap_entry(swp_entry_t, struct block_device**); |
51 | |
52 | DEFINE_SPINLOCK(swap_lock); |
53 | static unsigned int nr_swapfiles; |
54 | atomic_long_t nr_swap_pages; |
55 | /* |
56 | * Some modules use swappable objects and may try to swap them out under |
57 | * memory pressure (via the shrinker). Before doing so, they may wish to |
58 | * check to see if any swap space is available. |
59 | */ |
60 | EXPORT_SYMBOL_GPL(nr_swap_pages); |
61 | /* protected with swap_lock. reading in vm_swap_full() doesn't need lock */ |
62 | long total_swap_pages; |
63 | static int least_priority = -1; |
64 | |
65 | static const char Bad_file[] = "Bad swap file entry " ; |
66 | static const char Unused_file[] = "Unused swap file entry " ; |
67 | static const char Bad_offset[] = "Bad swap offset entry " ; |
68 | static const char Unused_offset[] = "Unused swap offset entry " ; |
69 | |
70 | /* |
71 | * all active swap_info_structs |
72 | * protected with swap_lock, and ordered by priority. |
73 | */ |
74 | PLIST_HEAD(swap_active_head); |
75 | |
76 | /* |
77 | * all available (active, not full) swap_info_structs |
78 | * protected with swap_avail_lock, ordered by priority. |
79 | * This is used by get_swap_page() instead of swap_active_head |
80 | * because swap_active_head includes all swap_info_structs, |
81 | * but get_swap_page() doesn't need to look at full ones. |
82 | * This uses its own lock instead of swap_lock because when a |
83 | * swap_info_struct changes between not-full/full, it needs to |
84 | * add/remove itself to/from this list, but the swap_info_struct->lock |
85 | * is held and the locking order requires swap_lock to be taken |
86 | * before any swap_info_struct->lock. |
87 | */ |
88 | static struct plist_head *swap_avail_heads; |
89 | static DEFINE_SPINLOCK(swap_avail_lock); |
90 | |
91 | struct swap_info_struct *swap_info[MAX_SWAPFILES]; |
92 | |
93 | static DEFINE_MUTEX(swapon_mutex); |
94 | |
95 | static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait); |
96 | /* Activity counter to indicate that a swapon or swapoff has occurred */ |
97 | static atomic_t proc_poll_event = ATOMIC_INIT(0); |
98 | |
99 | atomic_t nr_rotate_swap = ATOMIC_INIT(0); |
100 | |
101 | static struct swap_info_struct *swap_type_to_swap_info(int type) |
102 | { |
103 | if (type >= READ_ONCE(nr_swapfiles)) |
104 | return NULL; |
105 | |
106 | smp_rmb(); /* Pairs with smp_wmb in alloc_swap_info. */ |
107 | return READ_ONCE(swap_info[type]); |
108 | } |
109 | |
110 | static inline unsigned char swap_count(unsigned char ent) |
111 | { |
112 | return ent & ~SWAP_HAS_CACHE; /* may include COUNT_CONTINUED flag */ |
113 | } |
114 | |
115 | /* Reclaim the swap entry anyway if possible */ |
116 | #define TTRS_ANYWAY 0x1 |
117 | /* |
118 | * Reclaim the swap entry if there are no more mappings of the |
119 | * corresponding page |
120 | */ |
121 | #define TTRS_UNMAPPED 0x2 |
122 | /* Reclaim the swap entry if swap is getting full*/ |
123 | #define TTRS_FULL 0x4 |
124 | |
125 | /* returns 1 if swap entry is freed */ |
126 | static int __try_to_reclaim_swap(struct swap_info_struct *si, |
127 | unsigned long offset, unsigned long flags) |
128 | { |
129 | swp_entry_t entry = swp_entry(si->type, offset); |
130 | struct page *page; |
131 | int ret = 0; |
132 | |
133 | page = find_get_page(swap_address_space(entry), offset); |
134 | if (!page) |
135 | return 0; |
136 | /* |
137 | * When this function is called from scan_swap_map_slots() and it's |
138 | * called by vmscan.c at reclaiming pages. So, we hold a lock on a page, |
139 | * here. We have to use trylock for avoiding deadlock. This is a special |
140 | * case and you should use try_to_free_swap() with explicit lock_page() |
141 | * in usual operations. |
142 | */ |
143 | if (trylock_page(page)) { |
144 | if ((flags & TTRS_ANYWAY) || |
145 | ((flags & TTRS_UNMAPPED) && !page_mapped(page)) || |
146 | ((flags & TTRS_FULL) && mem_cgroup_swap_full(page))) |
147 | ret = try_to_free_swap(page); |
148 | unlock_page(page); |
149 | } |
150 | put_page(page); |
151 | return ret; |
152 | } |
153 | |
154 | /* |
155 | * swapon tell device that all the old swap contents can be discarded, |
156 | * to allow the swap device to optimize its wear-levelling. |
157 | */ |
158 | static int discard_swap(struct swap_info_struct *si) |
159 | { |
160 | struct swap_extent *se; |
161 | sector_t start_block; |
162 | sector_t nr_blocks; |
163 | int err = 0; |
164 | |
165 | /* Do not discard the swap header page! */ |
166 | se = &si->first_swap_extent; |
167 | start_block = (se->start_block + 1) << (PAGE_SHIFT - 9); |
168 | nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9); |
169 | if (nr_blocks) { |
170 | err = blkdev_issue_discard(si->bdev, start_block, |
171 | nr_blocks, GFP_KERNEL, 0); |
172 | if (err) |
173 | return err; |
174 | cond_resched(); |
175 | } |
176 | |
177 | list_for_each_entry(se, &si->first_swap_extent.list, list) { |
178 | start_block = se->start_block << (PAGE_SHIFT - 9); |
179 | nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); |
180 | |
181 | err = blkdev_issue_discard(si->bdev, start_block, |
182 | nr_blocks, GFP_KERNEL, 0); |
183 | if (err) |
184 | break; |
185 | |
186 | cond_resched(); |
187 | } |
188 | return err; /* That will often be -EOPNOTSUPP */ |
189 | } |
190 | |
191 | /* |
192 | * swap allocation tell device that a cluster of swap can now be discarded, |
193 | * to allow the swap device to optimize its wear-levelling. |
194 | */ |
195 | static void discard_swap_cluster(struct swap_info_struct *si, |
196 | pgoff_t start_page, pgoff_t nr_pages) |
197 | { |
198 | struct swap_extent *se = si->curr_swap_extent; |
199 | int found_extent = 0; |
200 | |
201 | while (nr_pages) { |
202 | if (se->start_page <= start_page && |
203 | start_page < se->start_page + se->nr_pages) { |
204 | pgoff_t offset = start_page - se->start_page; |
205 | sector_t start_block = se->start_block + offset; |
206 | sector_t nr_blocks = se->nr_pages - offset; |
207 | |
208 | if (nr_blocks > nr_pages) |
209 | nr_blocks = nr_pages; |
210 | start_page += nr_blocks; |
211 | nr_pages -= nr_blocks; |
212 | |
213 | if (!found_extent++) |
214 | si->curr_swap_extent = se; |
215 | |
216 | start_block <<= PAGE_SHIFT - 9; |
217 | nr_blocks <<= PAGE_SHIFT - 9; |
218 | if (blkdev_issue_discard(si->bdev, start_block, |
219 | nr_blocks, GFP_NOIO, 0)) |
220 | break; |
221 | } |
222 | |
223 | se = list_next_entry(se, list); |
224 | } |
225 | } |
226 | |
227 | #ifdef CONFIG_THP_SWAP |
228 | #define SWAPFILE_CLUSTER HPAGE_PMD_NR |
229 | |
230 | #define swap_entry_size(size) (size) |
231 | #else |
232 | #define SWAPFILE_CLUSTER 256 |
233 | |
234 | /* |
235 | * Define swap_entry_size() as constant to let compiler to optimize |
236 | * out some code if !CONFIG_THP_SWAP |
237 | */ |
238 | #define swap_entry_size(size) 1 |
239 | #endif |
240 | #define LATENCY_LIMIT 256 |
241 | |
242 | static inline void cluster_set_flag(struct swap_cluster_info *info, |
243 | unsigned int flag) |
244 | { |
245 | info->flags = flag; |
246 | } |
247 | |
248 | static inline unsigned int cluster_count(struct swap_cluster_info *info) |
249 | { |
250 | return info->data; |
251 | } |
252 | |
253 | static inline void cluster_set_count(struct swap_cluster_info *info, |
254 | unsigned int c) |
255 | { |
256 | info->data = c; |
257 | } |
258 | |
259 | static inline void cluster_set_count_flag(struct swap_cluster_info *info, |
260 | unsigned int c, unsigned int f) |
261 | { |
262 | info->flags = f; |
263 | info->data = c; |
264 | } |
265 | |
266 | static inline unsigned int cluster_next(struct swap_cluster_info *info) |
267 | { |
268 | return info->data; |
269 | } |
270 | |
271 | static inline void cluster_set_next(struct swap_cluster_info *info, |
272 | unsigned int n) |
273 | { |
274 | info->data = n; |
275 | } |
276 | |
277 | static inline void cluster_set_next_flag(struct swap_cluster_info *info, |
278 | unsigned int n, unsigned int f) |
279 | { |
280 | info->flags = f; |
281 | info->data = n; |
282 | } |
283 | |
284 | static inline bool cluster_is_free(struct swap_cluster_info *info) |
285 | { |
286 | return info->flags & CLUSTER_FLAG_FREE; |
287 | } |
288 | |
289 | static inline bool cluster_is_null(struct swap_cluster_info *info) |
290 | { |
291 | return info->flags & CLUSTER_FLAG_NEXT_NULL; |
292 | } |
293 | |
294 | static inline void cluster_set_null(struct swap_cluster_info *info) |
295 | { |
296 | info->flags = CLUSTER_FLAG_NEXT_NULL; |
297 | info->data = 0; |
298 | } |
299 | |
300 | static inline bool cluster_is_huge(struct swap_cluster_info *info) |
301 | { |
302 | if (IS_ENABLED(CONFIG_THP_SWAP)) |
303 | return info->flags & CLUSTER_FLAG_HUGE; |
304 | return false; |
305 | } |
306 | |
307 | static inline void cluster_clear_huge(struct swap_cluster_info *info) |
308 | { |
309 | info->flags &= ~CLUSTER_FLAG_HUGE; |
310 | } |
311 | |
312 | static inline struct swap_cluster_info *lock_cluster(struct swap_info_struct *si, |
313 | unsigned long offset) |
314 | { |
315 | struct swap_cluster_info *ci; |
316 | |
317 | ci = si->cluster_info; |
318 | if (ci) { |
319 | ci += offset / SWAPFILE_CLUSTER; |
320 | spin_lock(&ci->lock); |
321 | } |
322 | return ci; |
323 | } |
324 | |
325 | static inline void unlock_cluster(struct swap_cluster_info *ci) |
326 | { |
327 | if (ci) |
328 | spin_unlock(&ci->lock); |
329 | } |
330 | |
331 | /* |
332 | * Determine the locking method in use for this device. Return |
333 | * swap_cluster_info if SSD-style cluster-based locking is in place. |
334 | */ |
335 | static inline struct swap_cluster_info *lock_cluster_or_swap_info( |
336 | struct swap_info_struct *si, unsigned long offset) |
337 | { |
338 | struct swap_cluster_info *ci; |
339 | |
340 | /* Try to use fine-grained SSD-style locking if available: */ |
341 | ci = lock_cluster(si, offset); |
342 | /* Otherwise, fall back to traditional, coarse locking: */ |
343 | if (!ci) |
344 | spin_lock(&si->lock); |
345 | |
346 | return ci; |
347 | } |
348 | |
349 | static inline void unlock_cluster_or_swap_info(struct swap_info_struct *si, |
350 | struct swap_cluster_info *ci) |
351 | { |
352 | if (ci) |
353 | unlock_cluster(ci); |
354 | else |
355 | spin_unlock(&si->lock); |
356 | } |
357 | |
358 | static inline bool cluster_list_empty(struct swap_cluster_list *list) |
359 | { |
360 | return cluster_is_null(&list->head); |
361 | } |
362 | |
363 | static inline unsigned int cluster_list_first(struct swap_cluster_list *list) |
364 | { |
365 | return cluster_next(&list->head); |
366 | } |
367 | |
368 | static void cluster_list_init(struct swap_cluster_list *list) |
369 | { |
370 | cluster_set_null(&list->head); |
371 | cluster_set_null(&list->tail); |
372 | } |
373 | |
374 | static void cluster_list_add_tail(struct swap_cluster_list *list, |
375 | struct swap_cluster_info *ci, |
376 | unsigned int idx) |
377 | { |
378 | if (cluster_list_empty(list)) { |
379 | cluster_set_next_flag(&list->head, idx, 0); |
380 | cluster_set_next_flag(&list->tail, idx, 0); |
381 | } else { |
382 | struct swap_cluster_info *ci_tail; |
383 | unsigned int tail = cluster_next(&list->tail); |
384 | |
385 | /* |
386 | * Nested cluster lock, but both cluster locks are |
387 | * only acquired when we held swap_info_struct->lock |
388 | */ |
389 | ci_tail = ci + tail; |
390 | spin_lock_nested(&ci_tail->lock, SINGLE_DEPTH_NESTING); |
391 | cluster_set_next(ci_tail, idx); |
392 | spin_unlock(&ci_tail->lock); |
393 | cluster_set_next_flag(&list->tail, idx, 0); |
394 | } |
395 | } |
396 | |
397 | static unsigned int cluster_list_del_first(struct swap_cluster_list *list, |
398 | struct swap_cluster_info *ci) |
399 | { |
400 | unsigned int idx; |
401 | |
402 | idx = cluster_next(&list->head); |
403 | if (cluster_next(&list->tail) == idx) { |
404 | cluster_set_null(&list->head); |
405 | cluster_set_null(&list->tail); |
406 | } else |
407 | cluster_set_next_flag(&list->head, |
408 | cluster_next(&ci[idx]), 0); |
409 | |
410 | return idx; |
411 | } |
412 | |
413 | /* Add a cluster to discard list and schedule it to do discard */ |
414 | static void swap_cluster_schedule_discard(struct swap_info_struct *si, |
415 | unsigned int idx) |
416 | { |
417 | /* |
418 | * If scan_swap_map() can't find a free cluster, it will check |
419 | * si->swap_map directly. To make sure the discarding cluster isn't |
420 | * taken by scan_swap_map(), mark the swap entries bad (occupied). It |
421 | * will be cleared after discard |
422 | */ |
423 | memset(si->swap_map + idx * SWAPFILE_CLUSTER, |
424 | SWAP_MAP_BAD, SWAPFILE_CLUSTER); |
425 | |
426 | cluster_list_add_tail(&si->discard_clusters, si->cluster_info, idx); |
427 | |
428 | schedule_work(&si->discard_work); |
429 | } |
430 | |
431 | static void __free_cluster(struct swap_info_struct *si, unsigned long idx) |
432 | { |
433 | struct swap_cluster_info *ci = si->cluster_info; |
434 | |
435 | cluster_set_flag(ci + idx, CLUSTER_FLAG_FREE); |
436 | cluster_list_add_tail(&si->free_clusters, ci, idx); |
437 | } |
438 | |
439 | /* |
440 | * Doing discard actually. After a cluster discard is finished, the cluster |
441 | * will be added to free cluster list. caller should hold si->lock. |
442 | */ |
443 | static void swap_do_scheduled_discard(struct swap_info_struct *si) |
444 | { |
445 | struct swap_cluster_info *info, *ci; |
446 | unsigned int idx; |
447 | |
448 | info = si->cluster_info; |
449 | |
450 | while (!cluster_list_empty(&si->discard_clusters)) { |
451 | idx = cluster_list_del_first(&si->discard_clusters, info); |
452 | spin_unlock(&si->lock); |
453 | |
454 | discard_swap_cluster(si, idx * SWAPFILE_CLUSTER, |
455 | SWAPFILE_CLUSTER); |
456 | |
457 | spin_lock(&si->lock); |
458 | ci = lock_cluster(si, idx * SWAPFILE_CLUSTER); |
459 | __free_cluster(si, idx); |
460 | memset(si->swap_map + idx * SWAPFILE_CLUSTER, |
461 | 0, SWAPFILE_CLUSTER); |
462 | unlock_cluster(ci); |
463 | } |
464 | } |
465 | |
466 | static void swap_discard_work(struct work_struct *work) |
467 | { |
468 | struct swap_info_struct *si; |
469 | |
470 | si = container_of(work, struct swap_info_struct, discard_work); |
471 | |
472 | spin_lock(&si->lock); |
473 | swap_do_scheduled_discard(si); |
474 | spin_unlock(&si->lock); |
475 | } |
476 | |
477 | static void alloc_cluster(struct swap_info_struct *si, unsigned long idx) |
478 | { |
479 | struct swap_cluster_info *ci = si->cluster_info; |
480 | |
481 | VM_BUG_ON(cluster_list_first(&si->free_clusters) != idx); |
482 | cluster_list_del_first(&si->free_clusters, ci); |
483 | cluster_set_count_flag(ci + idx, 0, 0); |
484 | } |
485 | |
486 | static void free_cluster(struct swap_info_struct *si, unsigned long idx) |
487 | { |
488 | struct swap_cluster_info *ci = si->cluster_info + idx; |
489 | |
490 | VM_BUG_ON(cluster_count(ci) != 0); |
491 | /* |
492 | * If the swap is discardable, prepare discard the cluster |
493 | * instead of free it immediately. The cluster will be freed |
494 | * after discard. |
495 | */ |
496 | if ((si->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) == |
497 | (SWP_WRITEOK | SWP_PAGE_DISCARD)) { |
498 | swap_cluster_schedule_discard(si, idx); |
499 | return; |
500 | } |
501 | |
502 | __free_cluster(si, idx); |
503 | } |
504 | |
505 | /* |
506 | * The cluster corresponding to page_nr will be used. The cluster will be |
507 | * removed from free cluster list and its usage counter will be increased. |
508 | */ |
509 | static void inc_cluster_info_page(struct swap_info_struct *p, |
510 | struct swap_cluster_info *cluster_info, unsigned long page_nr) |
511 | { |
512 | unsigned long idx = page_nr / SWAPFILE_CLUSTER; |
513 | |
514 | if (!cluster_info) |
515 | return; |
516 | if (cluster_is_free(&cluster_info[idx])) |
517 | alloc_cluster(p, idx); |
518 | |
519 | VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER); |
520 | cluster_set_count(&cluster_info[idx], |
521 | cluster_count(&cluster_info[idx]) + 1); |
522 | } |
523 | |
524 | /* |
525 | * The cluster corresponding to page_nr decreases one usage. If the usage |
526 | * counter becomes 0, which means no page in the cluster is in using, we can |
527 | * optionally discard the cluster and add it to free cluster list. |
528 | */ |
529 | static void dec_cluster_info_page(struct swap_info_struct *p, |
530 | struct swap_cluster_info *cluster_info, unsigned long page_nr) |
531 | { |
532 | unsigned long idx = page_nr / SWAPFILE_CLUSTER; |
533 | |
534 | if (!cluster_info) |
535 | return; |
536 | |
537 | VM_BUG_ON(cluster_count(&cluster_info[idx]) == 0); |
538 | cluster_set_count(&cluster_info[idx], |
539 | cluster_count(&cluster_info[idx]) - 1); |
540 | |
541 | if (cluster_count(&cluster_info[idx]) == 0) |
542 | free_cluster(p, idx); |
543 | } |
544 | |
545 | /* |
546 | * It's possible scan_swap_map() uses a free cluster in the middle of free |
547 | * cluster list. Avoiding such abuse to avoid list corruption. |
548 | */ |
549 | static bool |
550 | scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si, |
551 | unsigned long offset) |
552 | { |
553 | struct percpu_cluster *percpu_cluster; |
554 | bool conflict; |
555 | |
556 | offset /= SWAPFILE_CLUSTER; |
557 | conflict = !cluster_list_empty(&si->free_clusters) && |
558 | offset != cluster_list_first(&si->free_clusters) && |
559 | cluster_is_free(&si->cluster_info[offset]); |
560 | |
561 | if (!conflict) |
562 | return false; |
563 | |
564 | percpu_cluster = this_cpu_ptr(si->percpu_cluster); |
565 | cluster_set_null(&percpu_cluster->index); |
566 | return true; |
567 | } |
568 | |
569 | /* |
570 | * Try to get a swap entry from current cpu's swap entry pool (a cluster). This |
571 | * might involve allocating a new cluster for current CPU too. |
572 | */ |
573 | static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si, |
574 | unsigned long *offset, unsigned long *scan_base) |
575 | { |
576 | struct percpu_cluster *cluster; |
577 | struct swap_cluster_info *ci; |
578 | bool found_free; |
579 | unsigned long tmp, max; |
580 | |
581 | new_cluster: |
582 | cluster = this_cpu_ptr(si->percpu_cluster); |
583 | if (cluster_is_null(&cluster->index)) { |
584 | if (!cluster_list_empty(&si->free_clusters)) { |
585 | cluster->index = si->free_clusters.head; |
586 | cluster->next = cluster_next(&cluster->index) * |
587 | SWAPFILE_CLUSTER; |
588 | } else if (!cluster_list_empty(&si->discard_clusters)) { |
589 | /* |
590 | * we don't have free cluster but have some clusters in |
591 | * discarding, do discard now and reclaim them |
592 | */ |
593 | swap_do_scheduled_discard(si); |
594 | *scan_base = *offset = si->cluster_next; |
595 | goto new_cluster; |
596 | } else |
597 | return false; |
598 | } |
599 | |
600 | found_free = false; |
601 | |
602 | /* |
603 | * Other CPUs can use our cluster if they can't find a free cluster, |
604 | * check if there is still free entry in the cluster |
605 | */ |
606 | tmp = cluster->next; |
607 | max = min_t(unsigned long, si->max, |
608 | (cluster_next(&cluster->index) + 1) * SWAPFILE_CLUSTER); |
609 | if (tmp >= max) { |
610 | cluster_set_null(&cluster->index); |
611 | goto new_cluster; |
612 | } |
613 | ci = lock_cluster(si, tmp); |
614 | while (tmp < max) { |
615 | if (!si->swap_map[tmp]) { |
616 | found_free = true; |
617 | break; |
618 | } |
619 | tmp++; |
620 | } |
621 | unlock_cluster(ci); |
622 | if (!found_free) { |
623 | cluster_set_null(&cluster->index); |
624 | goto new_cluster; |
625 | } |
626 | cluster->next = tmp + 1; |
627 | *offset = tmp; |
628 | *scan_base = tmp; |
629 | return found_free; |
630 | } |
631 | |
632 | static void __del_from_avail_list(struct swap_info_struct *p) |
633 | { |
634 | int nid; |
635 | |
636 | for_each_node(nid) |
637 | plist_del(&p->avail_lists[nid], &swap_avail_heads[nid]); |
638 | } |
639 | |
640 | static void del_from_avail_list(struct swap_info_struct *p) |
641 | { |
642 | spin_lock(&swap_avail_lock); |
643 | __del_from_avail_list(p); |
644 | spin_unlock(&swap_avail_lock); |
645 | } |
646 | |
647 | static void swap_range_alloc(struct swap_info_struct *si, unsigned long offset, |
648 | unsigned int nr_entries) |
649 | { |
650 | unsigned int end = offset + nr_entries - 1; |
651 | |
652 | if (offset == si->lowest_bit) |
653 | si->lowest_bit += nr_entries; |
654 | if (end == si->highest_bit) |
655 | si->highest_bit -= nr_entries; |
656 | si->inuse_pages += nr_entries; |
657 | if (si->inuse_pages == si->pages) { |
658 | si->lowest_bit = si->max; |
659 | si->highest_bit = 0; |
660 | del_from_avail_list(si); |
661 | } |
662 | } |
663 | |
664 | static void add_to_avail_list(struct swap_info_struct *p) |
665 | { |
666 | int nid; |
667 | |
668 | spin_lock(&swap_avail_lock); |
669 | for_each_node(nid) { |
670 | WARN_ON(!plist_node_empty(&p->avail_lists[nid])); |
671 | plist_add(&p->avail_lists[nid], &swap_avail_heads[nid]); |
672 | } |
673 | spin_unlock(&swap_avail_lock); |
674 | } |
675 | |
676 | static void swap_range_free(struct swap_info_struct *si, unsigned long offset, |
677 | unsigned int nr_entries) |
678 | { |
679 | unsigned long end = offset + nr_entries - 1; |
680 | void (*swap_slot_free_notify)(struct block_device *, unsigned long); |
681 | |
682 | if (offset < si->lowest_bit) |
683 | si->lowest_bit = offset; |
684 | if (end > si->highest_bit) { |
685 | bool was_full = !si->highest_bit; |
686 | |
687 | si->highest_bit = end; |
688 | if (was_full && (si->flags & SWP_WRITEOK)) |
689 | add_to_avail_list(si); |
690 | } |
691 | atomic_long_add(nr_entries, &nr_swap_pages); |
692 | si->inuse_pages -= nr_entries; |
693 | if (si->flags & SWP_BLKDEV) |
694 | swap_slot_free_notify = |
695 | si->bdev->bd_disk->fops->swap_slot_free_notify; |
696 | else |
697 | swap_slot_free_notify = NULL; |
698 | while (offset <= end) { |
699 | frontswap_invalidate_page(si->type, offset); |
700 | if (swap_slot_free_notify) |
701 | swap_slot_free_notify(si->bdev, offset); |
702 | offset++; |
703 | } |
704 | } |
705 | |
706 | static int scan_swap_map_slots(struct swap_info_struct *si, |
707 | unsigned char usage, int nr, |
708 | swp_entry_t slots[]) |
709 | { |
710 | struct swap_cluster_info *ci; |
711 | unsigned long offset; |
712 | unsigned long scan_base; |
713 | unsigned long last_in_cluster = 0; |
714 | int latency_ration = LATENCY_LIMIT; |
715 | int n_ret = 0; |
716 | |
717 | if (nr > SWAP_BATCH) |
718 | nr = SWAP_BATCH; |
719 | |
720 | /* |
721 | * We try to cluster swap pages by allocating them sequentially |
722 | * in swap. Once we've allocated SWAPFILE_CLUSTER pages this |
723 | * way, however, we resort to first-free allocation, starting |
724 | * a new cluster. This prevents us from scattering swap pages |
725 | * all over the entire swap partition, so that we reduce |
726 | * overall disk seek times between swap pages. -- sct |
727 | * But we do now try to find an empty cluster. -Andrea |
728 | * And we let swap pages go all over an SSD partition. Hugh |
729 | */ |
730 | |
731 | si->flags += SWP_SCANNING; |
732 | scan_base = offset = si->cluster_next; |
733 | |
734 | /* SSD algorithm */ |
735 | if (si->cluster_info) { |
736 | if (scan_swap_map_try_ssd_cluster(si, &offset, &scan_base)) |
737 | goto checks; |
738 | else |
739 | goto scan; |
740 | } |
741 | |
742 | if (unlikely(!si->cluster_nr--)) { |
743 | if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { |
744 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
745 | goto checks; |
746 | } |
747 | |
748 | spin_unlock(&si->lock); |
749 | |
750 | /* |
751 | * If seek is expensive, start searching for new cluster from |
752 | * start of partition, to minimize the span of allocated swap. |
753 | * If seek is cheap, that is the SWP_SOLIDSTATE si->cluster_info |
754 | * case, just handled by scan_swap_map_try_ssd_cluster() above. |
755 | */ |
756 | scan_base = offset = si->lowest_bit; |
757 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
758 | |
759 | /* Locate the first empty (unaligned) cluster */ |
760 | for (; last_in_cluster <= si->highest_bit; offset++) { |
761 | if (si->swap_map[offset]) |
762 | last_in_cluster = offset + SWAPFILE_CLUSTER; |
763 | else if (offset == last_in_cluster) { |
764 | spin_lock(&si->lock); |
765 | offset -= SWAPFILE_CLUSTER - 1; |
766 | si->cluster_next = offset; |
767 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
768 | goto checks; |
769 | } |
770 | if (unlikely(--latency_ration < 0)) { |
771 | cond_resched(); |
772 | latency_ration = LATENCY_LIMIT; |
773 | } |
774 | } |
775 | |
776 | offset = scan_base; |
777 | spin_lock(&si->lock); |
778 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
779 | } |
780 | |
781 | checks: |
782 | if (si->cluster_info) { |
783 | while (scan_swap_map_ssd_cluster_conflict(si, offset)) { |
784 | /* take a break if we already got some slots */ |
785 | if (n_ret) |
786 | goto done; |
787 | if (!scan_swap_map_try_ssd_cluster(si, &offset, |
788 | &scan_base)) |
789 | goto scan; |
790 | } |
791 | } |
792 | if (!(si->flags & SWP_WRITEOK)) |
793 | goto no_page; |
794 | if (!si->highest_bit) |
795 | goto no_page; |
796 | if (offset > si->highest_bit) |
797 | scan_base = offset = si->lowest_bit; |
798 | |
799 | ci = lock_cluster(si, offset); |
800 | /* reuse swap entry of cache-only swap if not busy. */ |
801 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
802 | int swap_was_freed; |
803 | unlock_cluster(ci); |
804 | spin_unlock(&si->lock); |
805 | swap_was_freed = __try_to_reclaim_swap(si, offset, TTRS_ANYWAY); |
806 | spin_lock(&si->lock); |
807 | /* entry was freed successfully, try to use this again */ |
808 | if (swap_was_freed) |
809 | goto checks; |
810 | goto scan; /* check next one */ |
811 | } |
812 | |
813 | if (si->swap_map[offset]) { |
814 | unlock_cluster(ci); |
815 | if (!n_ret) |
816 | goto scan; |
817 | else |
818 | goto done; |
819 | } |
820 | si->swap_map[offset] = usage; |
821 | inc_cluster_info_page(si, si->cluster_info, offset); |
822 | unlock_cluster(ci); |
823 | |
824 | swap_range_alloc(si, offset, 1); |
825 | si->cluster_next = offset + 1; |
826 | slots[n_ret++] = swp_entry(si->type, offset); |
827 | |
828 | /* got enough slots or reach max slots? */ |
829 | if ((n_ret == nr) || (offset >= si->highest_bit)) |
830 | goto done; |
831 | |
832 | /* search for next available slot */ |
833 | |
834 | /* time to take a break? */ |
835 | if (unlikely(--latency_ration < 0)) { |
836 | if (n_ret) |
837 | goto done; |
838 | spin_unlock(&si->lock); |
839 | cond_resched(); |
840 | spin_lock(&si->lock); |
841 | latency_ration = LATENCY_LIMIT; |
842 | } |
843 | |
844 | /* try to get more slots in cluster */ |
845 | if (si->cluster_info) { |
846 | if (scan_swap_map_try_ssd_cluster(si, &offset, &scan_base)) |
847 | goto checks; |
848 | else |
849 | goto done; |
850 | } |
851 | /* non-ssd case */ |
852 | ++offset; |
853 | |
854 | /* non-ssd case, still more slots in cluster? */ |
855 | if (si->cluster_nr && !si->swap_map[offset]) { |
856 | --si->cluster_nr; |
857 | goto checks; |
858 | } |
859 | |
860 | done: |
861 | si->flags -= SWP_SCANNING; |
862 | return n_ret; |
863 | |
864 | scan: |
865 | spin_unlock(&si->lock); |
866 | while (++offset <= si->highest_bit) { |
867 | if (!si->swap_map[offset]) { |
868 | spin_lock(&si->lock); |
869 | goto checks; |
870 | } |
871 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
872 | spin_lock(&si->lock); |
873 | goto checks; |
874 | } |
875 | if (unlikely(--latency_ration < 0)) { |
876 | cond_resched(); |
877 | latency_ration = LATENCY_LIMIT; |
878 | } |
879 | } |
880 | offset = si->lowest_bit; |
881 | while (offset < scan_base) { |
882 | if (!si->swap_map[offset]) { |
883 | spin_lock(&si->lock); |
884 | goto checks; |
885 | } |
886 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
887 | spin_lock(&si->lock); |
888 | goto checks; |
889 | } |
890 | if (unlikely(--latency_ration < 0)) { |
891 | cond_resched(); |
892 | latency_ration = LATENCY_LIMIT; |
893 | } |
894 | offset++; |
895 | } |
896 | spin_lock(&si->lock); |
897 | |
898 | no_page: |
899 | si->flags -= SWP_SCANNING; |
900 | return n_ret; |
901 | } |
902 | |
903 | static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) |
904 | { |
905 | unsigned long idx; |
906 | struct swap_cluster_info *ci; |
907 | unsigned long offset, i; |
908 | unsigned char *map; |
909 | |
910 | /* |
911 | * Should not even be attempting cluster allocations when huge |
912 | * page swap is disabled. Warn and fail the allocation. |
913 | */ |
914 | if (!IS_ENABLED(CONFIG_THP_SWAP)) { |
915 | VM_WARN_ON_ONCE(1); |
916 | return 0; |
917 | } |
918 | |
919 | if (cluster_list_empty(&si->free_clusters)) |
920 | return 0; |
921 | |
922 | idx = cluster_list_first(&si->free_clusters); |
923 | offset = idx * SWAPFILE_CLUSTER; |
924 | ci = lock_cluster(si, offset); |
925 | alloc_cluster(si, idx); |
926 | cluster_set_count_flag(ci, SWAPFILE_CLUSTER, CLUSTER_FLAG_HUGE); |
927 | |
928 | map = si->swap_map + offset; |
929 | for (i = 0; i < SWAPFILE_CLUSTER; i++) |
930 | map[i] = SWAP_HAS_CACHE; |
931 | unlock_cluster(ci); |
932 | swap_range_alloc(si, offset, SWAPFILE_CLUSTER); |
933 | *slot = swp_entry(si->type, offset); |
934 | |
935 | return 1; |
936 | } |
937 | |
938 | static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx) |
939 | { |
940 | unsigned long offset = idx * SWAPFILE_CLUSTER; |
941 | struct swap_cluster_info *ci; |
942 | |
943 | ci = lock_cluster(si, offset); |
944 | memset(si->swap_map + offset, 0, SWAPFILE_CLUSTER); |
945 | cluster_set_count_flag(ci, 0, 0); |
946 | free_cluster(si, idx); |
947 | unlock_cluster(ci); |
948 | swap_range_free(si, offset, SWAPFILE_CLUSTER); |
949 | } |
950 | |
951 | static unsigned long scan_swap_map(struct swap_info_struct *si, |
952 | unsigned char usage) |
953 | { |
954 | swp_entry_t entry; |
955 | int n_ret; |
956 | |
957 | n_ret = scan_swap_map_slots(si, usage, 1, &entry); |
958 | |
959 | if (n_ret) |
960 | return swp_offset(entry); |
961 | else |
962 | return 0; |
963 | |
964 | } |
965 | |
966 | int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size) |
967 | { |
968 | unsigned long size = swap_entry_size(entry_size); |
969 | struct swap_info_struct *si, *next; |
970 | long avail_pgs; |
971 | int n_ret = 0; |
972 | int node; |
973 | |
974 | /* Only single cluster request supported */ |
975 | WARN_ON_ONCE(n_goal > 1 && size == SWAPFILE_CLUSTER); |
976 | |
977 | avail_pgs = atomic_long_read(&nr_swap_pages) / size; |
978 | if (avail_pgs <= 0) |
979 | goto noswap; |
980 | |
981 | if (n_goal > SWAP_BATCH) |
982 | n_goal = SWAP_BATCH; |
983 | |
984 | if (n_goal > avail_pgs) |
985 | n_goal = avail_pgs; |
986 | |
987 | atomic_long_sub(n_goal * size, &nr_swap_pages); |
988 | |
989 | spin_lock(&swap_avail_lock); |
990 | |
991 | start_over: |
992 | node = numa_node_id(); |
993 | plist_for_each_entry_safe(si, next, &swap_avail_heads[node], avail_lists[node]) { |
994 | /* requeue si to after same-priority siblings */ |
995 | plist_requeue(&si->avail_lists[node], &swap_avail_heads[node]); |
996 | spin_unlock(&swap_avail_lock); |
997 | spin_lock(&si->lock); |
998 | if (!si->highest_bit || !(si->flags & SWP_WRITEOK)) { |
999 | spin_lock(&swap_avail_lock); |
1000 | if (plist_node_empty(&si->avail_lists[node])) { |
1001 | spin_unlock(&si->lock); |
1002 | goto nextsi; |
1003 | } |
1004 | WARN(!si->highest_bit, |
1005 | "swap_info %d in list but !highest_bit\n" , |
1006 | si->type); |
1007 | WARN(!(si->flags & SWP_WRITEOK), |
1008 | "swap_info %d in list but !SWP_WRITEOK\n" , |
1009 | si->type); |
1010 | __del_from_avail_list(si); |
1011 | spin_unlock(&si->lock); |
1012 | goto nextsi; |
1013 | } |
1014 | if (size == SWAPFILE_CLUSTER) { |
1015 | if (!(si->flags & SWP_FS)) |
1016 | n_ret = swap_alloc_cluster(si, swp_entries); |
1017 | } else |
1018 | n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, |
1019 | n_goal, swp_entries); |
1020 | spin_unlock(&si->lock); |
1021 | if (n_ret || size == SWAPFILE_CLUSTER) |
1022 | goto check_out; |
1023 | pr_debug("scan_swap_map of si %d failed to find offset\n" , |
1024 | si->type); |
1025 | |
1026 | spin_lock(&swap_avail_lock); |
1027 | nextsi: |
1028 | /* |
1029 | * if we got here, it's likely that si was almost full before, |
1030 | * and since scan_swap_map() can drop the si->lock, multiple |
1031 | * callers probably all tried to get a page from the same si |
1032 | * and it filled up before we could get one; or, the si filled |
1033 | * up between us dropping swap_avail_lock and taking si->lock. |
1034 | * Since we dropped the swap_avail_lock, the swap_avail_head |
1035 | * list may have been modified; so if next is still in the |
1036 | * swap_avail_head list then try it, otherwise start over |
1037 | * if we have not gotten any slots. |
1038 | */ |
1039 | if (plist_node_empty(&next->avail_lists[node])) |
1040 | goto start_over; |
1041 | } |
1042 | |
1043 | spin_unlock(&swap_avail_lock); |
1044 | |
1045 | check_out: |
1046 | if (n_ret < n_goal) |
1047 | atomic_long_add((long)(n_goal - n_ret) * size, |
1048 | &nr_swap_pages); |
1049 | noswap: |
1050 | return n_ret; |
1051 | } |
1052 | |
1053 | /* The only caller of this function is now suspend routine */ |
1054 | swp_entry_t get_swap_page_of_type(int type) |
1055 | { |
1056 | struct swap_info_struct *si = swap_type_to_swap_info(type); |
1057 | pgoff_t offset; |
1058 | |
1059 | if (!si) |
1060 | goto fail; |
1061 | |
1062 | spin_lock(&si->lock); |
1063 | if (si->flags & SWP_WRITEOK) { |
1064 | atomic_long_dec(&nr_swap_pages); |
1065 | /* This is called for allocating swap entry, not cache */ |
1066 | offset = scan_swap_map(si, 1); |
1067 | if (offset) { |
1068 | spin_unlock(&si->lock); |
1069 | return swp_entry(type, offset); |
1070 | } |
1071 | atomic_long_inc(&nr_swap_pages); |
1072 | } |
1073 | spin_unlock(&si->lock); |
1074 | fail: |
1075 | return (swp_entry_t) {0}; |
1076 | } |
1077 | |
1078 | static struct swap_info_struct *__swap_info_get(swp_entry_t entry) |
1079 | { |
1080 | struct swap_info_struct *p; |
1081 | unsigned long offset, type; |
1082 | |
1083 | if (!entry.val) |
1084 | goto out; |
1085 | type = swp_type(entry); |
1086 | p = swap_type_to_swap_info(type); |
1087 | if (!p) |
1088 | goto bad_nofile; |
1089 | if (!(p->flags & SWP_USED)) |
1090 | goto bad_device; |
1091 | offset = swp_offset(entry); |
1092 | if (offset >= p->max) |
1093 | goto bad_offset; |
1094 | return p; |
1095 | |
1096 | bad_offset: |
1097 | pr_err("swap_info_get: %s%08lx\n" , Bad_offset, entry.val); |
1098 | goto out; |
1099 | bad_device: |
1100 | pr_err("swap_info_get: %s%08lx\n" , Unused_file, entry.val); |
1101 | goto out; |
1102 | bad_nofile: |
1103 | pr_err("swap_info_get: %s%08lx\n" , Bad_file, entry.val); |
1104 | out: |
1105 | return NULL; |
1106 | } |
1107 | |
1108 | static struct swap_info_struct *_swap_info_get(swp_entry_t entry) |
1109 | { |
1110 | struct swap_info_struct *p; |
1111 | |
1112 | p = __swap_info_get(entry); |
1113 | if (!p) |
1114 | goto out; |
1115 | if (!p->swap_map[swp_offset(entry)]) |
1116 | goto bad_free; |
1117 | return p; |
1118 | |
1119 | bad_free: |
1120 | pr_err("swap_info_get: %s%08lx\n" , Unused_offset, entry.val); |
1121 | goto out; |
1122 | out: |
1123 | return NULL; |
1124 | } |
1125 | |
1126 | static struct swap_info_struct *swap_info_get(swp_entry_t entry) |
1127 | { |
1128 | struct swap_info_struct *p; |
1129 | |
1130 | p = _swap_info_get(entry); |
1131 | if (p) |
1132 | spin_lock(&p->lock); |
1133 | return p; |
1134 | } |
1135 | |
1136 | static struct swap_info_struct *swap_info_get_cont(swp_entry_t entry, |
1137 | struct swap_info_struct *q) |
1138 | { |
1139 | struct swap_info_struct *p; |
1140 | |
1141 | p = _swap_info_get(entry); |
1142 | |
1143 | if (p != q) { |
1144 | if (q != NULL) |
1145 | spin_unlock(&q->lock); |
1146 | if (p != NULL) |
1147 | spin_lock(&p->lock); |
1148 | } |
1149 | return p; |
1150 | } |
1151 | |
1152 | static unsigned char __swap_entry_free_locked(struct swap_info_struct *p, |
1153 | unsigned long offset, |
1154 | unsigned char usage) |
1155 | { |
1156 | unsigned char count; |
1157 | unsigned char has_cache; |
1158 | |
1159 | count = p->swap_map[offset]; |
1160 | |
1161 | has_cache = count & SWAP_HAS_CACHE; |
1162 | count &= ~SWAP_HAS_CACHE; |
1163 | |
1164 | if (usage == SWAP_HAS_CACHE) { |
1165 | VM_BUG_ON(!has_cache); |
1166 | has_cache = 0; |
1167 | } else if (count == SWAP_MAP_SHMEM) { |
1168 | /* |
1169 | * Or we could insist on shmem.c using a special |
1170 | * swap_shmem_free() and free_shmem_swap_and_cache()... |
1171 | */ |
1172 | count = 0; |
1173 | } else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) { |
1174 | if (count == COUNT_CONTINUED) { |
1175 | if (swap_count_continued(p, offset, count)) |
1176 | count = SWAP_MAP_MAX | COUNT_CONTINUED; |
1177 | else |
1178 | count = SWAP_MAP_MAX; |
1179 | } else |
1180 | count--; |
1181 | } |
1182 | |
1183 | usage = count | has_cache; |
1184 | p->swap_map[offset] = usage ? : SWAP_HAS_CACHE; |
1185 | |
1186 | return usage; |
1187 | } |
1188 | |
1189 | static unsigned char __swap_entry_free(struct swap_info_struct *p, |
1190 | swp_entry_t entry, unsigned char usage) |
1191 | { |
1192 | struct swap_cluster_info *ci; |
1193 | unsigned long offset = swp_offset(entry); |
1194 | |
1195 | ci = lock_cluster_or_swap_info(p, offset); |
1196 | usage = __swap_entry_free_locked(p, offset, usage); |
1197 | unlock_cluster_or_swap_info(p, ci); |
1198 | if (!usage) |
1199 | free_swap_slot(entry); |
1200 | |
1201 | return usage; |
1202 | } |
1203 | |
1204 | static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry) |
1205 | { |
1206 | struct swap_cluster_info *ci; |
1207 | unsigned long offset = swp_offset(entry); |
1208 | unsigned char count; |
1209 | |
1210 | ci = lock_cluster(p, offset); |
1211 | count = p->swap_map[offset]; |
1212 | VM_BUG_ON(count != SWAP_HAS_CACHE); |
1213 | p->swap_map[offset] = 0; |
1214 | dec_cluster_info_page(p, p->cluster_info, offset); |
1215 | unlock_cluster(ci); |
1216 | |
1217 | mem_cgroup_uncharge_swap(entry, 1); |
1218 | swap_range_free(p, offset, 1); |
1219 | } |
1220 | |
1221 | /* |
1222 | * Caller has made sure that the swap device corresponding to entry |
1223 | * is still around or has not been recycled. |
1224 | */ |
1225 | void swap_free(swp_entry_t entry) |
1226 | { |
1227 | struct swap_info_struct *p; |
1228 | |
1229 | p = _swap_info_get(entry); |
1230 | if (p) |
1231 | __swap_entry_free(p, entry, 1); |
1232 | } |
1233 | |
1234 | /* |
1235 | * Called after dropping swapcache to decrease refcnt to swap entries. |
1236 | */ |
1237 | void put_swap_page(struct page *page, swp_entry_t entry) |
1238 | { |
1239 | unsigned long offset = swp_offset(entry); |
1240 | unsigned long idx = offset / SWAPFILE_CLUSTER; |
1241 | struct swap_cluster_info *ci; |
1242 | struct swap_info_struct *si; |
1243 | unsigned char *map; |
1244 | unsigned int i, free_entries = 0; |
1245 | unsigned char val; |
1246 | int size = swap_entry_size(hpage_nr_pages(page)); |
1247 | |
1248 | si = _swap_info_get(entry); |
1249 | if (!si) |
1250 | return; |
1251 | |
1252 | ci = lock_cluster_or_swap_info(si, offset); |
1253 | if (size == SWAPFILE_CLUSTER) { |
1254 | VM_BUG_ON(!cluster_is_huge(ci)); |
1255 | map = si->swap_map + offset; |
1256 | for (i = 0; i < SWAPFILE_CLUSTER; i++) { |
1257 | val = map[i]; |
1258 | VM_BUG_ON(!(val & SWAP_HAS_CACHE)); |
1259 | if (val == SWAP_HAS_CACHE) |
1260 | free_entries++; |
1261 | } |
1262 | cluster_clear_huge(ci); |
1263 | if (free_entries == SWAPFILE_CLUSTER) { |
1264 | unlock_cluster_or_swap_info(si, ci); |
1265 | spin_lock(&si->lock); |
1266 | mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER); |
1267 | swap_free_cluster(si, idx); |
1268 | spin_unlock(&si->lock); |
1269 | return; |
1270 | } |
1271 | } |
1272 | for (i = 0; i < size; i++, entry.val++) { |
1273 | if (!__swap_entry_free_locked(si, offset + i, SWAP_HAS_CACHE)) { |
1274 | unlock_cluster_or_swap_info(si, ci); |
1275 | free_swap_slot(entry); |
1276 | if (i == size - 1) |
1277 | return; |
1278 | lock_cluster_or_swap_info(si, offset); |
1279 | } |
1280 | } |
1281 | unlock_cluster_or_swap_info(si, ci); |
1282 | } |
1283 | |
1284 | #ifdef CONFIG_THP_SWAP |
1285 | int split_swap_cluster(swp_entry_t entry) |
1286 | { |
1287 | struct swap_info_struct *si; |
1288 | struct swap_cluster_info *ci; |
1289 | unsigned long offset = swp_offset(entry); |
1290 | |
1291 | si = _swap_info_get(entry); |
1292 | if (!si) |
1293 | return -EBUSY; |
1294 | ci = lock_cluster(si, offset); |
1295 | cluster_clear_huge(ci); |
1296 | unlock_cluster(ci); |
1297 | return 0; |
1298 | } |
1299 | #endif |
1300 | |
1301 | static int swp_entry_cmp(const void *ent1, const void *ent2) |
1302 | { |
1303 | const swp_entry_t *e1 = ent1, *e2 = ent2; |
1304 | |
1305 | return (int)swp_type(*e1) - (int)swp_type(*e2); |
1306 | } |
1307 | |
1308 | void swapcache_free_entries(swp_entry_t *entries, int n) |
1309 | { |
1310 | struct swap_info_struct *p, *prev; |
1311 | int i; |
1312 | |
1313 | if (n <= 0) |
1314 | return; |
1315 | |
1316 | prev = NULL; |
1317 | p = NULL; |
1318 | |
1319 | /* |
1320 | * Sort swap entries by swap device, so each lock is only taken once. |
1321 | * nr_swapfiles isn't absolutely correct, but the overhead of sort() is |
1322 | * so low that it isn't necessary to optimize further. |
1323 | */ |
1324 | if (nr_swapfiles > 1) |
1325 | sort(entries, n, sizeof(entries[0]), swp_entry_cmp, NULL); |
1326 | for (i = 0; i < n; ++i) { |
1327 | p = swap_info_get_cont(entries[i], prev); |
1328 | if (p) |
1329 | swap_entry_free(p, entries[i]); |
1330 | prev = p; |
1331 | } |
1332 | if (p) |
1333 | spin_unlock(&p->lock); |
1334 | } |
1335 | |
1336 | /* |
1337 | * How many references to page are currently swapped out? |
1338 | * This does not give an exact answer when swap count is continued, |
1339 | * but does include the high COUNT_CONTINUED flag to allow for that. |
1340 | */ |
1341 | int page_swapcount(struct page *page) |
1342 | { |
1343 | int count = 0; |
1344 | struct swap_info_struct *p; |
1345 | struct swap_cluster_info *ci; |
1346 | swp_entry_t entry; |
1347 | unsigned long offset; |
1348 | |
1349 | entry.val = page_private(page); |
1350 | p = _swap_info_get(entry); |
1351 | if (p) { |
1352 | offset = swp_offset(entry); |
1353 | ci = lock_cluster_or_swap_info(p, offset); |
1354 | count = swap_count(p->swap_map[offset]); |
1355 | unlock_cluster_or_swap_info(p, ci); |
1356 | } |
1357 | return count; |
1358 | } |
1359 | |
1360 | int __swap_count(struct swap_info_struct *si, swp_entry_t entry) |
1361 | { |
1362 | pgoff_t offset = swp_offset(entry); |
1363 | |
1364 | return swap_count(si->swap_map[offset]); |
1365 | } |
1366 | |
1367 | static int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry) |
1368 | { |
1369 | int count = 0; |
1370 | pgoff_t offset = swp_offset(entry); |
1371 | struct swap_cluster_info *ci; |
1372 | |
1373 | ci = lock_cluster_or_swap_info(si, offset); |
1374 | count = swap_count(si->swap_map[offset]); |
1375 | unlock_cluster_or_swap_info(si, ci); |
1376 | return count; |
1377 | } |
1378 | |
1379 | /* |
1380 | * How many references to @entry are currently swapped out? |
1381 | * This does not give an exact answer when swap count is continued, |
1382 | * but does include the high COUNT_CONTINUED flag to allow for that. |
1383 | */ |
1384 | int __swp_swapcount(swp_entry_t entry) |
1385 | { |
1386 | int count = 0; |
1387 | struct swap_info_struct *si; |
1388 | |
1389 | si = __swap_info_get(entry); |
1390 | if (si) |
1391 | count = swap_swapcount(si, entry); |
1392 | return count; |
1393 | } |
1394 | |
1395 | /* |
1396 | * How many references to @entry are currently swapped out? |
1397 | * This considers COUNT_CONTINUED so it returns exact answer. |
1398 | */ |
1399 | int swp_swapcount(swp_entry_t entry) |
1400 | { |
1401 | int count, tmp_count, n; |
1402 | struct swap_info_struct *p; |
1403 | struct swap_cluster_info *ci; |
1404 | struct page *page; |
1405 | pgoff_t offset; |
1406 | unsigned char *map; |
1407 | |
1408 | p = _swap_info_get(entry); |
1409 | if (!p) |
1410 | return 0; |
1411 | |
1412 | offset = swp_offset(entry); |
1413 | |
1414 | ci = lock_cluster_or_swap_info(p, offset); |
1415 | |
1416 | count = swap_count(p->swap_map[offset]); |
1417 | if (!(count & COUNT_CONTINUED)) |
1418 | goto out; |
1419 | |
1420 | count &= ~COUNT_CONTINUED; |
1421 | n = SWAP_MAP_MAX + 1; |
1422 | |
1423 | page = vmalloc_to_page(p->swap_map + offset); |
1424 | offset &= ~PAGE_MASK; |
1425 | VM_BUG_ON(page_private(page) != SWP_CONTINUED); |
1426 | |
1427 | do { |
1428 | page = list_next_entry(page, lru); |
1429 | map = kmap_atomic(page); |
1430 | tmp_count = map[offset]; |
1431 | kunmap_atomic(map); |
1432 | |
1433 | count += (tmp_count & ~COUNT_CONTINUED) * n; |
1434 | n *= (SWAP_CONT_MAX + 1); |
1435 | } while (tmp_count & COUNT_CONTINUED); |
1436 | out: |
1437 | unlock_cluster_or_swap_info(p, ci); |
1438 | return count; |
1439 | } |
1440 | |
1441 | static bool swap_page_trans_huge_swapped(struct swap_info_struct *si, |
1442 | swp_entry_t entry) |
1443 | { |
1444 | struct swap_cluster_info *ci; |
1445 | unsigned char *map = si->swap_map; |
1446 | unsigned long roffset = swp_offset(entry); |
1447 | unsigned long offset = round_down(roffset, SWAPFILE_CLUSTER); |
1448 | int i; |
1449 | bool ret = false; |
1450 | |
1451 | ci = lock_cluster_or_swap_info(si, offset); |
1452 | if (!ci || !cluster_is_huge(ci)) { |
1453 | if (swap_count(map[roffset])) |
1454 | ret = true; |
1455 | goto unlock_out; |
1456 | } |
1457 | for (i = 0; i < SWAPFILE_CLUSTER; i++) { |
1458 | if (swap_count(map[offset + i])) { |
1459 | ret = true; |
1460 | break; |
1461 | } |
1462 | } |
1463 | unlock_out: |
1464 | unlock_cluster_or_swap_info(si, ci); |
1465 | return ret; |
1466 | } |
1467 | |
1468 | static bool page_swapped(struct page *page) |
1469 | { |
1470 | swp_entry_t entry; |
1471 | struct swap_info_struct *si; |
1472 | |
1473 | if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!PageTransCompound(page))) |
1474 | return page_swapcount(page) != 0; |
1475 | |
1476 | page = compound_head(page); |
1477 | entry.val = page_private(page); |
1478 | si = _swap_info_get(entry); |
1479 | if (si) |
1480 | return swap_page_trans_huge_swapped(si, entry); |
1481 | return false; |
1482 | } |
1483 | |
1484 | static int page_trans_huge_map_swapcount(struct page *page, int *total_mapcount, |
1485 | int *total_swapcount) |
1486 | { |
1487 | int i, map_swapcount, _total_mapcount, _total_swapcount; |
1488 | unsigned long offset = 0; |
1489 | struct swap_info_struct *si; |
1490 | struct swap_cluster_info *ci = NULL; |
1491 | unsigned char *map = NULL; |
1492 | int mapcount, swapcount = 0; |
1493 | |
1494 | /* hugetlbfs shouldn't call it */ |
1495 | VM_BUG_ON_PAGE(PageHuge(page), page); |
1496 | |
1497 | if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!PageTransCompound(page))) { |
1498 | mapcount = page_trans_huge_mapcount(page, total_mapcount); |
1499 | if (PageSwapCache(page)) |
1500 | swapcount = page_swapcount(page); |
1501 | if (total_swapcount) |
1502 | *total_swapcount = swapcount; |
1503 | return mapcount + swapcount; |
1504 | } |
1505 | |
1506 | page = compound_head(page); |
1507 | |
1508 | _total_mapcount = _total_swapcount = map_swapcount = 0; |
1509 | if (PageSwapCache(page)) { |
1510 | swp_entry_t entry; |
1511 | |
1512 | entry.val = page_private(page); |
1513 | si = _swap_info_get(entry); |
1514 | if (si) { |
1515 | map = si->swap_map; |
1516 | offset = swp_offset(entry); |
1517 | } |
1518 | } |
1519 | if (map) |
1520 | ci = lock_cluster(si, offset); |
1521 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
1522 | mapcount = atomic_read(&page[i]._mapcount) + 1; |
1523 | _total_mapcount += mapcount; |
1524 | if (map) { |
1525 | swapcount = swap_count(map[offset + i]); |
1526 | _total_swapcount += swapcount; |
1527 | } |
1528 | map_swapcount = max(map_swapcount, mapcount + swapcount); |
1529 | } |
1530 | unlock_cluster(ci); |
1531 | if (PageDoubleMap(page)) { |
1532 | map_swapcount -= 1; |
1533 | _total_mapcount -= HPAGE_PMD_NR; |
1534 | } |
1535 | mapcount = compound_mapcount(page); |
1536 | map_swapcount += mapcount; |
1537 | _total_mapcount += mapcount; |
1538 | if (total_mapcount) |
1539 | *total_mapcount = _total_mapcount; |
1540 | if (total_swapcount) |
1541 | *total_swapcount = _total_swapcount; |
1542 | |
1543 | return map_swapcount; |
1544 | } |
1545 | |
1546 | /* |
1547 | * We can write to an anon page without COW if there are no other references |
1548 | * to it. And as a side-effect, free up its swap: because the old content |
1549 | * on disk will never be read, and seeking back there to write new content |
1550 | * later would only waste time away from clustering. |
1551 | * |
1552 | * NOTE: total_map_swapcount should not be relied upon by the caller if |
1553 | * reuse_swap_page() returns false, but it may be always overwritten |
1554 | * (see the other implementation for CONFIG_SWAP=n). |
1555 | */ |
1556 | bool reuse_swap_page(struct page *page, int *total_map_swapcount) |
1557 | { |
1558 | int count, total_mapcount, total_swapcount; |
1559 | |
1560 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
1561 | if (unlikely(PageKsm(page))) |
1562 | return false; |
1563 | count = page_trans_huge_map_swapcount(page, &total_mapcount, |
1564 | &total_swapcount); |
1565 | if (total_map_swapcount) |
1566 | *total_map_swapcount = total_mapcount + total_swapcount; |
1567 | if (count == 1 && PageSwapCache(page) && |
1568 | (likely(!PageTransCompound(page)) || |
1569 | /* The remaining swap count will be freed soon */ |
1570 | total_swapcount == page_swapcount(page))) { |
1571 | if (!PageWriteback(page)) { |
1572 | page = compound_head(page); |
1573 | delete_from_swap_cache(page); |
1574 | SetPageDirty(page); |
1575 | } else { |
1576 | swp_entry_t entry; |
1577 | struct swap_info_struct *p; |
1578 | |
1579 | entry.val = page_private(page); |
1580 | p = swap_info_get(entry); |
1581 | if (p->flags & SWP_STABLE_WRITES) { |
1582 | spin_unlock(&p->lock); |
1583 | return false; |
1584 | } |
1585 | spin_unlock(&p->lock); |
1586 | } |
1587 | } |
1588 | |
1589 | return count <= 1; |
1590 | } |
1591 | |
1592 | /* |
1593 | * If swap is getting full, or if there are no more mappings of this page, |
1594 | * then try_to_free_swap is called to free its swap space. |
1595 | */ |
1596 | int try_to_free_swap(struct page *page) |
1597 | { |
1598 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
1599 | |
1600 | if (!PageSwapCache(page)) |
1601 | return 0; |
1602 | if (PageWriteback(page)) |
1603 | return 0; |
1604 | if (page_swapped(page)) |
1605 | return 0; |
1606 | |
1607 | /* |
1608 | * Once hibernation has begun to create its image of memory, |
1609 | * there's a danger that one of the calls to try_to_free_swap() |
1610 | * - most probably a call from __try_to_reclaim_swap() while |
1611 | * hibernation is allocating its own swap pages for the image, |
1612 | * but conceivably even a call from memory reclaim - will free |
1613 | * the swap from a page which has already been recorded in the |
1614 | * image as a clean swapcache page, and then reuse its swap for |
1615 | * another page of the image. On waking from hibernation, the |
1616 | * original page might be freed under memory pressure, then |
1617 | * later read back in from swap, now with the wrong data. |
1618 | * |
1619 | * Hibernation suspends storage while it is writing the image |
1620 | * to disk so check that here. |
1621 | */ |
1622 | if (pm_suspended_storage()) |
1623 | return 0; |
1624 | |
1625 | page = compound_head(page); |
1626 | delete_from_swap_cache(page); |
1627 | SetPageDirty(page); |
1628 | return 1; |
1629 | } |
1630 | |
1631 | /* |
1632 | * Free the swap entry like above, but also try to |
1633 | * free the page cache entry if it is the last user. |
1634 | */ |
1635 | int free_swap_and_cache(swp_entry_t entry) |
1636 | { |
1637 | struct swap_info_struct *p; |
1638 | unsigned char count; |
1639 | |
1640 | if (non_swap_entry(entry)) |
1641 | return 1; |
1642 | |
1643 | p = _swap_info_get(entry); |
1644 | if (p) { |
1645 | count = __swap_entry_free(p, entry, 1); |
1646 | if (count == SWAP_HAS_CACHE && |
1647 | !swap_page_trans_huge_swapped(p, entry)) |
1648 | __try_to_reclaim_swap(p, swp_offset(entry), |
1649 | TTRS_UNMAPPED | TTRS_FULL); |
1650 | } |
1651 | return p != NULL; |
1652 | } |
1653 | |
1654 | #ifdef CONFIG_HIBERNATION |
1655 | /* |
1656 | * Find the swap type that corresponds to given device (if any). |
1657 | * |
1658 | * @offset - number of the PAGE_SIZE-sized block of the device, starting |
1659 | * from 0, in which the swap header is expected to be located. |
1660 | * |
1661 | * This is needed for the suspend to disk (aka swsusp). |
1662 | */ |
1663 | int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) |
1664 | { |
1665 | struct block_device *bdev = NULL; |
1666 | int type; |
1667 | |
1668 | if (device) |
1669 | bdev = bdget(device); |
1670 | |
1671 | spin_lock(&swap_lock); |
1672 | for (type = 0; type < nr_swapfiles; type++) { |
1673 | struct swap_info_struct *sis = swap_info[type]; |
1674 | |
1675 | if (!(sis->flags & SWP_WRITEOK)) |
1676 | continue; |
1677 | |
1678 | if (!bdev) { |
1679 | if (bdev_p) |
1680 | *bdev_p = bdgrab(sis->bdev); |
1681 | |
1682 | spin_unlock(&swap_lock); |
1683 | return type; |
1684 | } |
1685 | if (bdev == sis->bdev) { |
1686 | struct swap_extent *se = &sis->first_swap_extent; |
1687 | |
1688 | if (se->start_block == offset) { |
1689 | if (bdev_p) |
1690 | *bdev_p = bdgrab(sis->bdev); |
1691 | |
1692 | spin_unlock(&swap_lock); |
1693 | bdput(bdev); |
1694 | return type; |
1695 | } |
1696 | } |
1697 | } |
1698 | spin_unlock(&swap_lock); |
1699 | if (bdev) |
1700 | bdput(bdev); |
1701 | |
1702 | return -ENODEV; |
1703 | } |
1704 | |
1705 | /* |
1706 | * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev |
1707 | * corresponding to given index in swap_info (swap type). |
1708 | */ |
1709 | sector_t swapdev_block(int type, pgoff_t offset) |
1710 | { |
1711 | struct block_device *bdev; |
1712 | struct swap_info_struct *si = swap_type_to_swap_info(type); |
1713 | |
1714 | if (!si || !(si->flags & SWP_WRITEOK)) |
1715 | return 0; |
1716 | return map_swap_entry(swp_entry(type, offset), &bdev); |
1717 | } |
1718 | |
1719 | /* |
1720 | * Return either the total number of swap pages of given type, or the number |
1721 | * of free pages of that type (depending on @free) |
1722 | * |
1723 | * This is needed for software suspend |
1724 | */ |
1725 | unsigned int count_swap_pages(int type, int free) |
1726 | { |
1727 | unsigned int n = 0; |
1728 | |
1729 | spin_lock(&swap_lock); |
1730 | if ((unsigned int)type < nr_swapfiles) { |
1731 | struct swap_info_struct *sis = swap_info[type]; |
1732 | |
1733 | spin_lock(&sis->lock); |
1734 | if (sis->flags & SWP_WRITEOK) { |
1735 | n = sis->pages; |
1736 | if (free) |
1737 | n -= sis->inuse_pages; |
1738 | } |
1739 | spin_unlock(&sis->lock); |
1740 | } |
1741 | spin_unlock(&swap_lock); |
1742 | return n; |
1743 | } |
1744 | #endif /* CONFIG_HIBERNATION */ |
1745 | |
1746 | static inline int pte_same_as_swp(pte_t pte, pte_t swp_pte) |
1747 | { |
1748 | return pte_same(pte_swp_clear_soft_dirty(pte), swp_pte); |
1749 | } |
1750 | |
1751 | /* |
1752 | * No need to decide whether this PTE shares the swap entry with others, |
1753 | * just let do_wp_page work it out if a write is requested later - to |
1754 | * force COW, vm_page_prot omits write permission from any private vma. |
1755 | */ |
1756 | static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, |
1757 | unsigned long addr, swp_entry_t entry, struct page *page) |
1758 | { |
1759 | struct page *swapcache; |
1760 | struct mem_cgroup *memcg; |
1761 | spinlock_t *ptl; |
1762 | pte_t *pte; |
1763 | int ret = 1; |
1764 | |
1765 | swapcache = page; |
1766 | page = ksm_might_need_to_copy(page, vma, addr); |
1767 | if (unlikely(!page)) |
1768 | return -ENOMEM; |
1769 | |
1770 | if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, |
1771 | &memcg, false)) { |
1772 | ret = -ENOMEM; |
1773 | goto out_nolock; |
1774 | } |
1775 | |
1776 | pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); |
1777 | if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) { |
1778 | mem_cgroup_cancel_charge(page, memcg, false); |
1779 | ret = 0; |
1780 | goto out; |
1781 | } |
1782 | |
1783 | dec_mm_counter(vma->vm_mm, MM_SWAPENTS); |
1784 | inc_mm_counter(vma->vm_mm, MM_ANONPAGES); |
1785 | get_page(page); |
1786 | set_pte_at(vma->vm_mm, addr, pte, |
1787 | pte_mkold(mk_pte(page, vma->vm_page_prot))); |
1788 | if (page == swapcache) { |
1789 | page_add_anon_rmap(page, vma, addr, false); |
1790 | mem_cgroup_commit_charge(page, memcg, true, false); |
1791 | } else { /* ksm created a completely new copy */ |
1792 | page_add_new_anon_rmap(page, vma, addr, false); |
1793 | mem_cgroup_commit_charge(page, memcg, false, false); |
1794 | lru_cache_add_active_or_unevictable(page, vma); |
1795 | } |
1796 | swap_free(entry); |
1797 | /* |
1798 | * Move the page to the active list so it is not |
1799 | * immediately swapped out again after swapon. |
1800 | */ |
1801 | activate_page(page); |
1802 | out: |
1803 | pte_unmap_unlock(pte, ptl); |
1804 | out_nolock: |
1805 | if (page != swapcache) { |
1806 | unlock_page(page); |
1807 | put_page(page); |
1808 | } |
1809 | return ret; |
1810 | } |
1811 | |
1812 | static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, |
1813 | unsigned long addr, unsigned long end, |
1814 | unsigned int type, bool frontswap, |
1815 | unsigned long *fs_pages_to_unuse) |
1816 | { |
1817 | struct page *page; |
1818 | swp_entry_t entry; |
1819 | pte_t *pte; |
1820 | struct swap_info_struct *si; |
1821 | unsigned long offset; |
1822 | int ret = 0; |
1823 | volatile unsigned char *swap_map; |
1824 | |
1825 | si = swap_info[type]; |
1826 | pte = pte_offset_map(pmd, addr); |
1827 | do { |
1828 | struct vm_fault vmf; |
1829 | |
1830 | if (!is_swap_pte(*pte)) |
1831 | continue; |
1832 | |
1833 | entry = pte_to_swp_entry(*pte); |
1834 | if (swp_type(entry) != type) |
1835 | continue; |
1836 | |
1837 | offset = swp_offset(entry); |
1838 | if (frontswap && !frontswap_test(si, offset)) |
1839 | continue; |
1840 | |
1841 | pte_unmap(pte); |
1842 | swap_map = &si->swap_map[offset]; |
1843 | vmf.vma = vma; |
1844 | vmf.address = addr; |
1845 | vmf.pmd = pmd; |
1846 | page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, &vmf); |
1847 | if (!page) { |
1848 | if (*swap_map == 0 || *swap_map == SWAP_MAP_BAD) |
1849 | goto try_next; |
1850 | return -ENOMEM; |
1851 | } |
1852 | |
1853 | lock_page(page); |
1854 | wait_on_page_writeback(page); |
1855 | ret = unuse_pte(vma, pmd, addr, entry, page); |
1856 | if (ret < 0) { |
1857 | unlock_page(page); |
1858 | put_page(page); |
1859 | goto out; |
1860 | } |
1861 | |
1862 | try_to_free_swap(page); |
1863 | unlock_page(page); |
1864 | put_page(page); |
1865 | |
1866 | if (*fs_pages_to_unuse && !--(*fs_pages_to_unuse)) { |
1867 | ret = FRONTSWAP_PAGES_UNUSED; |
1868 | goto out; |
1869 | } |
1870 | try_next: |
1871 | pte = pte_offset_map(pmd, addr); |
1872 | } while (pte++, addr += PAGE_SIZE, addr != end); |
1873 | pte_unmap(pte - 1); |
1874 | |
1875 | ret = 0; |
1876 | out: |
1877 | return ret; |
1878 | } |
1879 | |
1880 | static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, |
1881 | unsigned long addr, unsigned long end, |
1882 | unsigned int type, bool frontswap, |
1883 | unsigned long *fs_pages_to_unuse) |
1884 | { |
1885 | pmd_t *pmd; |
1886 | unsigned long next; |
1887 | int ret; |
1888 | |
1889 | pmd = pmd_offset(pud, addr); |
1890 | do { |
1891 | cond_resched(); |
1892 | next = pmd_addr_end(addr, end); |
1893 | if (pmd_none_or_trans_huge_or_clear_bad(pmd)) |
1894 | continue; |
1895 | ret = unuse_pte_range(vma, pmd, addr, next, type, |
1896 | frontswap, fs_pages_to_unuse); |
1897 | if (ret) |
1898 | return ret; |
1899 | } while (pmd++, addr = next, addr != end); |
1900 | return 0; |
1901 | } |
1902 | |
1903 | static inline int unuse_pud_range(struct vm_area_struct *vma, p4d_t *p4d, |
1904 | unsigned long addr, unsigned long end, |
1905 | unsigned int type, bool frontswap, |
1906 | unsigned long *fs_pages_to_unuse) |
1907 | { |
1908 | pud_t *pud; |
1909 | unsigned long next; |
1910 | int ret; |
1911 | |
1912 | pud = pud_offset(p4d, addr); |
1913 | do { |
1914 | next = pud_addr_end(addr, end); |
1915 | if (pud_none_or_clear_bad(pud)) |
1916 | continue; |
1917 | ret = unuse_pmd_range(vma, pud, addr, next, type, |
1918 | frontswap, fs_pages_to_unuse); |
1919 | if (ret) |
1920 | return ret; |
1921 | } while (pud++, addr = next, addr != end); |
1922 | return 0; |
1923 | } |
1924 | |
1925 | static inline int unuse_p4d_range(struct vm_area_struct *vma, pgd_t *pgd, |
1926 | unsigned long addr, unsigned long end, |
1927 | unsigned int type, bool frontswap, |
1928 | unsigned long *fs_pages_to_unuse) |
1929 | { |
1930 | p4d_t *p4d; |
1931 | unsigned long next; |
1932 | int ret; |
1933 | |
1934 | p4d = p4d_offset(pgd, addr); |
1935 | do { |
1936 | next = p4d_addr_end(addr, end); |
1937 | if (p4d_none_or_clear_bad(p4d)) |
1938 | continue; |
1939 | ret = unuse_pud_range(vma, p4d, addr, next, type, |
1940 | frontswap, fs_pages_to_unuse); |
1941 | if (ret) |
1942 | return ret; |
1943 | } while (p4d++, addr = next, addr != end); |
1944 | return 0; |
1945 | } |
1946 | |
1947 | static int unuse_vma(struct vm_area_struct *vma, unsigned int type, |
1948 | bool frontswap, unsigned long *fs_pages_to_unuse) |
1949 | { |
1950 | pgd_t *pgd; |
1951 | unsigned long addr, end, next; |
1952 | int ret; |
1953 | |
1954 | addr = vma->vm_start; |
1955 | end = vma->vm_end; |
1956 | |
1957 | pgd = pgd_offset(vma->vm_mm, addr); |
1958 | do { |
1959 | next = pgd_addr_end(addr, end); |
1960 | if (pgd_none_or_clear_bad(pgd)) |
1961 | continue; |
1962 | ret = unuse_p4d_range(vma, pgd, addr, next, type, |
1963 | frontswap, fs_pages_to_unuse); |
1964 | if (ret) |
1965 | return ret; |
1966 | } while (pgd++, addr = next, addr != end); |
1967 | return 0; |
1968 | } |
1969 | |
1970 | static int unuse_mm(struct mm_struct *mm, unsigned int type, |
1971 | bool frontswap, unsigned long *fs_pages_to_unuse) |
1972 | { |
1973 | struct vm_area_struct *vma; |
1974 | int ret = 0; |
1975 | |
1976 | down_read(&mm->mmap_sem); |
1977 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
1978 | if (vma->anon_vma) { |
1979 | ret = unuse_vma(vma, type, frontswap, |
1980 | fs_pages_to_unuse); |
1981 | if (ret) |
1982 | break; |
1983 | } |
1984 | cond_resched(); |
1985 | } |
1986 | up_read(&mm->mmap_sem); |
1987 | return ret; |
1988 | } |
1989 | |
1990 | /* |
1991 | * Scan swap_map (or frontswap_map if frontswap parameter is true) |
1992 | * from current position to next entry still in use. Return 0 |
1993 | * if there are no inuse entries after prev till end of the map. |
1994 | */ |
1995 | static unsigned int find_next_to_unuse(struct swap_info_struct *si, |
1996 | unsigned int prev, bool frontswap) |
1997 | { |
1998 | unsigned int i; |
1999 | unsigned char count; |
2000 | |
2001 | /* |
2002 | * No need for swap_lock here: we're just looking |
2003 | * for whether an entry is in use, not modifying it; false |
2004 | * hits are okay, and sys_swapoff() has already prevented new |
2005 | * allocations from this area (while holding swap_lock). |
2006 | */ |
2007 | for (i = prev + 1; i < si->max; i++) { |
2008 | count = READ_ONCE(si->swap_map[i]); |
2009 | if (count && swap_count(count) != SWAP_MAP_BAD) |
2010 | if (!frontswap || frontswap_test(si, i)) |
2011 | break; |
2012 | if ((i % LATENCY_LIMIT) == 0) |
2013 | cond_resched(); |
2014 | } |
2015 | |
2016 | if (i == si->max) |
2017 | i = 0; |
2018 | |
2019 | return i; |
2020 | } |
2021 | |
2022 | /* |
2023 | * If the boolean frontswap is true, only unuse pages_to_unuse pages; |
2024 | * pages_to_unuse==0 means all pages; ignored if frontswap is false |
2025 | */ |
2026 | #define SWAP_UNUSE_MAX_TRIES 3 |
2027 | int try_to_unuse(unsigned int type, bool frontswap, |
2028 | unsigned long pages_to_unuse) |
2029 | { |
2030 | struct mm_struct *prev_mm; |
2031 | struct mm_struct *mm; |
2032 | struct list_head *p; |
2033 | int retval = 0; |
2034 | struct swap_info_struct *si = swap_info[type]; |
2035 | struct page *page; |
2036 | swp_entry_t entry; |
2037 | unsigned int i; |
2038 | int retries = 0; |
2039 | |
2040 | if (!si->inuse_pages) |
2041 | return 0; |
2042 | |
2043 | if (!frontswap) |
2044 | pages_to_unuse = 0; |
2045 | |
2046 | retry: |
2047 | retval = shmem_unuse(type, frontswap, &pages_to_unuse); |
2048 | if (retval) |
2049 | goto out; |
2050 | |
2051 | prev_mm = &init_mm; |
2052 | mmget(prev_mm); |
2053 | |
2054 | spin_lock(&mmlist_lock); |
2055 | p = &init_mm.mmlist; |
2056 | while ((p = p->next) != &init_mm.mmlist) { |
2057 | if (signal_pending(current)) { |
2058 | retval = -EINTR; |
2059 | break; |
2060 | } |
2061 | |
2062 | mm = list_entry(p, struct mm_struct, mmlist); |
2063 | if (!mmget_not_zero(mm)) |
2064 | continue; |
2065 | spin_unlock(&mmlist_lock); |
2066 | mmput(prev_mm); |
2067 | prev_mm = mm; |
2068 | retval = unuse_mm(mm, type, frontswap, &pages_to_unuse); |
2069 | |
2070 | if (retval) { |
2071 | mmput(prev_mm); |
2072 | goto out; |
2073 | } |
2074 | |
2075 | /* |
2076 | * Make sure that we aren't completely killing |
2077 | * interactive performance. |
2078 | */ |
2079 | cond_resched(); |
2080 | spin_lock(&mmlist_lock); |
2081 | } |
2082 | spin_unlock(&mmlist_lock); |
2083 | |
2084 | mmput(prev_mm); |
2085 | |
2086 | i = 0; |
2087 | while ((i = find_next_to_unuse(si, i, frontswap)) != 0) { |
2088 | |
2089 | entry = swp_entry(type, i); |
2090 | page = find_get_page(swap_address_space(entry), i); |
2091 | if (!page) |
2092 | continue; |
2093 | |
2094 | /* |
2095 | * It is conceivable that a racing task removed this page from |
2096 | * swap cache just before we acquired the page lock. The page |
2097 | * might even be back in swap cache on another swap area. But |
2098 | * that is okay, try_to_free_swap() only removes stale pages. |
2099 | */ |
2100 | lock_page(page); |
2101 | wait_on_page_writeback(page); |
2102 | try_to_free_swap(page); |
2103 | unlock_page(page); |
2104 | put_page(page); |
2105 | |
2106 | /* |
2107 | * For frontswap, we just need to unuse pages_to_unuse, if |
2108 | * it was specified. Need not check frontswap again here as |
2109 | * we already zeroed out pages_to_unuse if not frontswap. |
2110 | */ |
2111 | if (pages_to_unuse && --pages_to_unuse == 0) |
2112 | goto out; |
2113 | } |
2114 | |
2115 | /* |
2116 | * Lets check again to see if there are still swap entries in the map. |
2117 | * If yes, we would need to do retry the unuse logic again. |
2118 | * Under global memory pressure, swap entries can be reinserted back |
2119 | * into process space after the mmlist loop above passes over them. |
2120 | * Its not worth continuosuly retrying to unuse the swap in this case. |
2121 | * So we try SWAP_UNUSE_MAX_TRIES times. |
2122 | */ |
2123 | if (++retries >= SWAP_UNUSE_MAX_TRIES) |
2124 | retval = -EBUSY; |
2125 | else if (si->inuse_pages) |
2126 | goto retry; |
2127 | |
2128 | out: |
2129 | return (retval == FRONTSWAP_PAGES_UNUSED) ? 0 : retval; |
2130 | } |
2131 | |
2132 | /* |
2133 | * After a successful try_to_unuse, if no swap is now in use, we know |
2134 | * we can empty the mmlist. swap_lock must be held on entry and exit. |
2135 | * Note that mmlist_lock nests inside swap_lock, and an mm must be |
2136 | * added to the mmlist just after page_duplicate - before would be racy. |
2137 | */ |
2138 | static void drain_mmlist(void) |
2139 | { |
2140 | struct list_head *p, *next; |
2141 | unsigned int type; |
2142 | |
2143 | for (type = 0; type < nr_swapfiles; type++) |
2144 | if (swap_info[type]->inuse_pages) |
2145 | return; |
2146 | spin_lock(&mmlist_lock); |
2147 | list_for_each_safe(p, next, &init_mm.mmlist) |
2148 | list_del_init(p); |
2149 | spin_unlock(&mmlist_lock); |
2150 | } |
2151 | |
2152 | /* |
2153 | * Use this swapdev's extent info to locate the (PAGE_SIZE) block which |
2154 | * corresponds to page offset for the specified swap entry. |
2155 | * Note that the type of this function is sector_t, but it returns page offset |
2156 | * into the bdev, not sector offset. |
2157 | */ |
2158 | static sector_t map_swap_entry(swp_entry_t entry, struct block_device **bdev) |
2159 | { |
2160 | struct swap_info_struct *sis; |
2161 | struct swap_extent *start_se; |
2162 | struct swap_extent *se; |
2163 | pgoff_t offset; |
2164 | |
2165 | sis = swp_swap_info(entry); |
2166 | *bdev = sis->bdev; |
2167 | |
2168 | offset = swp_offset(entry); |
2169 | start_se = sis->curr_swap_extent; |
2170 | se = start_se; |
2171 | |
2172 | for ( ; ; ) { |
2173 | if (se->start_page <= offset && |
2174 | offset < (se->start_page + se->nr_pages)) { |
2175 | return se->start_block + (offset - se->start_page); |
2176 | } |
2177 | se = list_next_entry(se, list); |
2178 | sis->curr_swap_extent = se; |
2179 | BUG_ON(se == start_se); /* It *must* be present */ |
2180 | } |
2181 | } |
2182 | |
2183 | /* |
2184 | * Returns the page offset into bdev for the specified page's swap entry. |
2185 | */ |
2186 | sector_t map_swap_page(struct page *page, struct block_device **bdev) |
2187 | { |
2188 | swp_entry_t entry; |
2189 | entry.val = page_private(page); |
2190 | return map_swap_entry(entry, bdev); |
2191 | } |
2192 | |
2193 | /* |
2194 | * Free all of a swapdev's extent information |
2195 | */ |
2196 | static void destroy_swap_extents(struct swap_info_struct *sis) |
2197 | { |
2198 | while (!list_empty(&sis->first_swap_extent.list)) { |
2199 | struct swap_extent *se; |
2200 | |
2201 | se = list_first_entry(&sis->first_swap_extent.list, |
2202 | struct swap_extent, list); |
2203 | list_del(&se->list); |
2204 | kfree(se); |
2205 | } |
2206 | |
2207 | if (sis->flags & SWP_ACTIVATED) { |
2208 | struct file *swap_file = sis->swap_file; |
2209 | struct address_space *mapping = swap_file->f_mapping; |
2210 | |
2211 | sis->flags &= ~SWP_ACTIVATED; |
2212 | if (mapping->a_ops->swap_deactivate) |
2213 | mapping->a_ops->swap_deactivate(swap_file); |
2214 | } |
2215 | } |
2216 | |
2217 | /* |
2218 | * Add a block range (and the corresponding page range) into this swapdev's |
2219 | * extent list. The extent list is kept sorted in page order. |
2220 | * |
2221 | * This function rather assumes that it is called in ascending page order. |
2222 | */ |
2223 | int |
2224 | add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, |
2225 | unsigned long nr_pages, sector_t start_block) |
2226 | { |
2227 | struct swap_extent *se; |
2228 | struct swap_extent *new_se; |
2229 | struct list_head *lh; |
2230 | |
2231 | if (start_page == 0) { |
2232 | se = &sis->first_swap_extent; |
2233 | sis->curr_swap_extent = se; |
2234 | se->start_page = 0; |
2235 | se->nr_pages = nr_pages; |
2236 | se->start_block = start_block; |
2237 | return 1; |
2238 | } else { |
2239 | lh = sis->first_swap_extent.list.prev; /* Highest extent */ |
2240 | se = list_entry(lh, struct swap_extent, list); |
2241 | BUG_ON(se->start_page + se->nr_pages != start_page); |
2242 | if (se->start_block + se->nr_pages == start_block) { |
2243 | /* Merge it */ |
2244 | se->nr_pages += nr_pages; |
2245 | return 0; |
2246 | } |
2247 | } |
2248 | |
2249 | /* |
2250 | * No merge. Insert a new extent, preserving ordering. |
2251 | */ |
2252 | new_se = kmalloc(sizeof(*se), GFP_KERNEL); |
2253 | if (new_se == NULL) |
2254 | return -ENOMEM; |
2255 | new_se->start_page = start_page; |
2256 | new_se->nr_pages = nr_pages; |
2257 | new_se->start_block = start_block; |
2258 | |
2259 | list_add_tail(&new_se->list, &sis->first_swap_extent.list); |
2260 | return 1; |
2261 | } |
2262 | EXPORT_SYMBOL_GPL(add_swap_extent); |
2263 | |
2264 | /* |
2265 | * A `swap extent' is a simple thing which maps a contiguous range of pages |
2266 | * onto a contiguous range of disk blocks. An ordered list of swap extents |
2267 | * is built at swapon time and is then used at swap_writepage/swap_readpage |
2268 | * time for locating where on disk a page belongs. |
2269 | * |
2270 | * If the swapfile is an S_ISBLK block device, a single extent is installed. |
2271 | * This is done so that the main operating code can treat S_ISBLK and S_ISREG |
2272 | * swap files identically. |
2273 | * |
2274 | * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap |
2275 | * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK |
2276 | * swapfiles are handled *identically* after swapon time. |
2277 | * |
2278 | * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks |
2279 | * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If |
2280 | * some stray blocks are found which do not fall within the PAGE_SIZE alignment |
2281 | * requirements, they are simply tossed out - we will never use those blocks |
2282 | * for swapping. |
2283 | * |
2284 | * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This |
2285 | * prevents root from shooting her foot off by ftruncating an in-use swapfile, |
2286 | * which will scribble on the fs. |
2287 | * |
2288 | * The amount of disk space which a single swap extent represents varies. |
2289 | * Typically it is in the 1-4 megabyte range. So we can have hundreds of |
2290 | * extents in the list. To avoid much list walking, we cache the previous |
2291 | * search location in `curr_swap_extent', and start new searches from there. |
2292 | * This is extremely effective. The average number of iterations in |
2293 | * map_swap_page() has been measured at about 0.3 per page. - akpm. |
2294 | */ |
2295 | static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) |
2296 | { |
2297 | struct file *swap_file = sis->swap_file; |
2298 | struct address_space *mapping = swap_file->f_mapping; |
2299 | struct inode *inode = mapping->host; |
2300 | int ret; |
2301 | |
2302 | if (S_ISBLK(inode->i_mode)) { |
2303 | ret = add_swap_extent(sis, 0, sis->max, 0); |
2304 | *span = sis->pages; |
2305 | return ret; |
2306 | } |
2307 | |
2308 | if (mapping->a_ops->swap_activate) { |
2309 | ret = mapping->a_ops->swap_activate(sis, swap_file, span); |
2310 | if (ret >= 0) |
2311 | sis->flags |= SWP_ACTIVATED; |
2312 | if (!ret) { |
2313 | sis->flags |= SWP_FS; |
2314 | ret = add_swap_extent(sis, 0, sis->max, 0); |
2315 | *span = sis->pages; |
2316 | } |
2317 | return ret; |
2318 | } |
2319 | |
2320 | return generic_swapfile_activate(sis, swap_file, span); |
2321 | } |
2322 | |
2323 | static int swap_node(struct swap_info_struct *p) |
2324 | { |
2325 | struct block_device *bdev; |
2326 | |
2327 | if (p->bdev) |
2328 | bdev = p->bdev; |
2329 | else |
2330 | bdev = p->swap_file->f_inode->i_sb->s_bdev; |
2331 | |
2332 | return bdev ? bdev->bd_disk->node_id : NUMA_NO_NODE; |
2333 | } |
2334 | |
2335 | static void _enable_swap_info(struct swap_info_struct *p, int prio, |
2336 | unsigned char *swap_map, |
2337 | struct swap_cluster_info *cluster_info) |
2338 | { |
2339 | int i; |
2340 | |
2341 | if (prio >= 0) |
2342 | p->prio = prio; |
2343 | else |
2344 | p->prio = --least_priority; |
2345 | /* |
2346 | * the plist prio is negated because plist ordering is |
2347 | * low-to-high, while swap ordering is high-to-low |
2348 | */ |
2349 | p->list.prio = -p->prio; |
2350 | for_each_node(i) { |
2351 | if (p->prio >= 0) |
2352 | p->avail_lists[i].prio = -p->prio; |
2353 | else { |
2354 | if (swap_node(p) == i) |
2355 | p->avail_lists[i].prio = 1; |
2356 | else |
2357 | p->avail_lists[i].prio = -p->prio; |
2358 | } |
2359 | } |
2360 | p->swap_map = swap_map; |
2361 | p->cluster_info = cluster_info; |
2362 | p->flags |= SWP_WRITEOK; |
2363 | atomic_long_add(p->pages, &nr_swap_pages); |
2364 | total_swap_pages += p->pages; |
2365 | |
2366 | assert_spin_locked(&swap_lock); |
2367 | /* |
2368 | * both lists are plists, and thus priority ordered. |
2369 | * swap_active_head needs to be priority ordered for swapoff(), |
2370 | * which on removal of any swap_info_struct with an auto-assigned |
2371 | * (i.e. negative) priority increments the auto-assigned priority |
2372 | * of any lower-priority swap_info_structs. |
2373 | * swap_avail_head needs to be priority ordered for get_swap_page(), |
2374 | * which allocates swap pages from the highest available priority |
2375 | * swap_info_struct. |
2376 | */ |
2377 | plist_add(&p->list, &swap_active_head); |
2378 | add_to_avail_list(p); |
2379 | } |
2380 | |
2381 | static void enable_swap_info(struct swap_info_struct *p, int prio, |
2382 | unsigned char *swap_map, |
2383 | struct swap_cluster_info *cluster_info, |
2384 | unsigned long *frontswap_map) |
2385 | { |
2386 | frontswap_init(p->type, frontswap_map); |
2387 | spin_lock(&swap_lock); |
2388 | spin_lock(&p->lock); |
2389 | _enable_swap_info(p, prio, swap_map, cluster_info); |
2390 | spin_unlock(&p->lock); |
2391 | spin_unlock(&swap_lock); |
2392 | } |
2393 | |
2394 | static void reinsert_swap_info(struct swap_info_struct *p) |
2395 | { |
2396 | spin_lock(&swap_lock); |
2397 | spin_lock(&p->lock); |
2398 | _enable_swap_info(p, p->prio, p->swap_map, p->cluster_info); |
2399 | spin_unlock(&p->lock); |
2400 | spin_unlock(&swap_lock); |
2401 | } |
2402 | |
2403 | bool has_usable_swap(void) |
2404 | { |
2405 | bool ret = true; |
2406 | |
2407 | spin_lock(&swap_lock); |
2408 | if (plist_head_empty(&swap_active_head)) |
2409 | ret = false; |
2410 | spin_unlock(&swap_lock); |
2411 | return ret; |
2412 | } |
2413 | |
2414 | SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) |
2415 | { |
2416 | struct swap_info_struct *p = NULL; |
2417 | unsigned char *swap_map; |
2418 | struct swap_cluster_info *cluster_info; |
2419 | unsigned long *frontswap_map; |
2420 | struct file *swap_file, *victim; |
2421 | struct address_space *mapping; |
2422 | struct inode *inode; |
2423 | struct filename *pathname; |
2424 | int err, found = 0; |
2425 | unsigned int old_block_size; |
2426 | |
2427 | if (!capable(CAP_SYS_ADMIN)) |
2428 | return -EPERM; |
2429 | |
2430 | BUG_ON(!current->mm); |
2431 | |
2432 | pathname = getname(specialfile); |
2433 | if (IS_ERR(pathname)) |
2434 | return PTR_ERR(pathname); |
2435 | |
2436 | victim = file_open_name(pathname, O_RDWR|O_LARGEFILE, 0); |
2437 | err = PTR_ERR(victim); |
2438 | if (IS_ERR(victim)) |
2439 | goto out; |
2440 | |
2441 | mapping = victim->f_mapping; |
2442 | spin_lock(&swap_lock); |
2443 | plist_for_each_entry(p, &swap_active_head, list) { |
2444 | if (p->flags & SWP_WRITEOK) { |
2445 | if (p->swap_file->f_mapping == mapping) { |
2446 | found = 1; |
2447 | break; |
2448 | } |
2449 | } |
2450 | } |
2451 | if (!found) { |
2452 | err = -EINVAL; |
2453 | spin_unlock(&swap_lock); |
2454 | goto out_dput; |
2455 | } |
2456 | if (!security_vm_enough_memory_mm(current->mm, p->pages)) |
2457 | vm_unacct_memory(p->pages); |
2458 | else { |
2459 | err = -ENOMEM; |
2460 | spin_unlock(&swap_lock); |
2461 | goto out_dput; |
2462 | } |
2463 | del_from_avail_list(p); |
2464 | spin_lock(&p->lock); |
2465 | if (p->prio < 0) { |
2466 | struct swap_info_struct *si = p; |
2467 | int nid; |
2468 | |
2469 | plist_for_each_entry_continue(si, &swap_active_head, list) { |
2470 | si->prio++; |
2471 | si->list.prio--; |
2472 | for_each_node(nid) { |
2473 | if (si->avail_lists[nid].prio != 1) |
2474 | si->avail_lists[nid].prio--; |
2475 | } |
2476 | } |
2477 | least_priority++; |
2478 | } |
2479 | plist_del(&p->list, &swap_active_head); |
2480 | atomic_long_sub(p->pages, &nr_swap_pages); |
2481 | total_swap_pages -= p->pages; |
2482 | p->flags &= ~SWP_WRITEOK; |
2483 | spin_unlock(&p->lock); |
2484 | spin_unlock(&swap_lock); |
2485 | |
2486 | disable_swap_slots_cache_lock(); |
2487 | |
2488 | set_current_oom_origin(); |
2489 | err = try_to_unuse(p->type, false, 0); /* force unuse all pages */ |
2490 | clear_current_oom_origin(); |
2491 | |
2492 | if (err) { |
2493 | /* re-insert swap space back into swap_list */ |
2494 | reinsert_swap_info(p); |
2495 | reenable_swap_slots_cache_unlock(); |
2496 | goto out_dput; |
2497 | } |
2498 | |
2499 | reenable_swap_slots_cache_unlock(); |
2500 | |
2501 | flush_work(&p->discard_work); |
2502 | |
2503 | destroy_swap_extents(p); |
2504 | if (p->flags & SWP_CONTINUED) |
2505 | free_swap_count_continuations(p); |
2506 | |
2507 | if (!p->bdev || !blk_queue_nonrot(bdev_get_queue(p->bdev))) |
2508 | atomic_dec(&nr_rotate_swap); |
2509 | |
2510 | mutex_lock(&swapon_mutex); |
2511 | spin_lock(&swap_lock); |
2512 | spin_lock(&p->lock); |
2513 | drain_mmlist(); |
2514 | |
2515 | /* wait for anyone still in scan_swap_map */ |
2516 | p->highest_bit = 0; /* cuts scans short */ |
2517 | while (p->flags >= SWP_SCANNING) { |
2518 | spin_unlock(&p->lock); |
2519 | spin_unlock(&swap_lock); |
2520 | schedule_timeout_uninterruptible(1); |
2521 | spin_lock(&swap_lock); |
2522 | spin_lock(&p->lock); |
2523 | } |
2524 | |
2525 | swap_file = p->swap_file; |
2526 | old_block_size = p->old_block_size; |
2527 | p->swap_file = NULL; |
2528 | p->max = 0; |
2529 | swap_map = p->swap_map; |
2530 | p->swap_map = NULL; |
2531 | cluster_info = p->cluster_info; |
2532 | p->cluster_info = NULL; |
2533 | frontswap_map = frontswap_map_get(p); |
2534 | spin_unlock(&p->lock); |
2535 | spin_unlock(&swap_lock); |
2536 | frontswap_invalidate_area(p->type); |
2537 | frontswap_map_set(p, NULL); |
2538 | mutex_unlock(&swapon_mutex); |
2539 | free_percpu(p->percpu_cluster); |
2540 | p->percpu_cluster = NULL; |
2541 | vfree(swap_map); |
2542 | kvfree(cluster_info); |
2543 | kvfree(frontswap_map); |
2544 | /* Destroy swap account information */ |
2545 | swap_cgroup_swapoff(p->type); |
2546 | exit_swap_address_space(p->type); |
2547 | |
2548 | inode = mapping->host; |
2549 | if (S_ISBLK(inode->i_mode)) { |
2550 | struct block_device *bdev = I_BDEV(inode); |
2551 | set_blocksize(bdev, old_block_size); |
2552 | blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); |
2553 | } else { |
2554 | inode_lock(inode); |
2555 | inode->i_flags &= ~S_SWAPFILE; |
2556 | inode_unlock(inode); |
2557 | } |
2558 | filp_close(swap_file, NULL); |
2559 | |
2560 | /* |
2561 | * Clear the SWP_USED flag after all resources are freed so that swapon |
2562 | * can reuse this swap_info in alloc_swap_info() safely. It is ok to |
2563 | * not hold p->lock after we cleared its SWP_WRITEOK. |
2564 | */ |
2565 | spin_lock(&swap_lock); |
2566 | p->flags = 0; |
2567 | spin_unlock(&swap_lock); |
2568 | |
2569 | err = 0; |
2570 | atomic_inc(&proc_poll_event); |
2571 | wake_up_interruptible(&proc_poll_wait); |
2572 | |
2573 | out_dput: |
2574 | filp_close(victim, NULL); |
2575 | out: |
2576 | putname(pathname); |
2577 | return err; |
2578 | } |
2579 | |
2580 | #ifdef CONFIG_PROC_FS |
2581 | static __poll_t swaps_poll(struct file *file, poll_table *wait) |
2582 | { |
2583 | struct seq_file *seq = file->private_data; |
2584 | |
2585 | poll_wait(file, &proc_poll_wait, wait); |
2586 | |
2587 | if (seq->poll_event != atomic_read(&proc_poll_event)) { |
2588 | seq->poll_event = atomic_read(&proc_poll_event); |
2589 | return EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI; |
2590 | } |
2591 | |
2592 | return EPOLLIN | EPOLLRDNORM; |
2593 | } |
2594 | |
2595 | /* iterator */ |
2596 | static void *swap_start(struct seq_file *swap, loff_t *pos) |
2597 | { |
2598 | struct swap_info_struct *si; |
2599 | int type; |
2600 | loff_t l = *pos; |
2601 | |
2602 | mutex_lock(&swapon_mutex); |
2603 | |
2604 | if (!l) |
2605 | return SEQ_START_TOKEN; |
2606 | |
2607 | for (type = 0; (si = swap_type_to_swap_info(type)); type++) { |
2608 | if (!(si->flags & SWP_USED) || !si->swap_map) |
2609 | continue; |
2610 | if (!--l) |
2611 | return si; |
2612 | } |
2613 | |
2614 | return NULL; |
2615 | } |
2616 | |
2617 | static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) |
2618 | { |
2619 | struct swap_info_struct *si = v; |
2620 | int type; |
2621 | |
2622 | if (v == SEQ_START_TOKEN) |
2623 | type = 0; |
2624 | else |
2625 | type = si->type + 1; |
2626 | |
2627 | for (; (si = swap_type_to_swap_info(type)); type++) { |
2628 | if (!(si->flags & SWP_USED) || !si->swap_map) |
2629 | continue; |
2630 | ++*pos; |
2631 | return si; |
2632 | } |
2633 | |
2634 | return NULL; |
2635 | } |
2636 | |
2637 | static void swap_stop(struct seq_file *swap, void *v) |
2638 | { |
2639 | mutex_unlock(&swapon_mutex); |
2640 | } |
2641 | |
2642 | static int swap_show(struct seq_file *swap, void *v) |
2643 | { |
2644 | struct swap_info_struct *si = v; |
2645 | struct file *file; |
2646 | int len; |
2647 | |
2648 | if (si == SEQ_START_TOKEN) { |
2649 | seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n" ); |
2650 | return 0; |
2651 | } |
2652 | |
2653 | file = si->swap_file; |
2654 | len = seq_file_path(swap, file, " \t\n\\" ); |
2655 | seq_printf(swap, "%*s%s\t%u\t%u\t%d\n" , |
2656 | len < 40 ? 40 - len : 1, " " , |
2657 | S_ISBLK(file_inode(file)->i_mode) ? |
2658 | "partition" : "file\t" , |
2659 | si->pages << (PAGE_SHIFT - 10), |
2660 | si->inuse_pages << (PAGE_SHIFT - 10), |
2661 | si->prio); |
2662 | return 0; |
2663 | } |
2664 | |
2665 | static const struct seq_operations swaps_op = { |
2666 | .start = swap_start, |
2667 | .next = swap_next, |
2668 | .stop = swap_stop, |
2669 | .show = swap_show |
2670 | }; |
2671 | |
2672 | static int swaps_open(struct inode *inode, struct file *file) |
2673 | { |
2674 | struct seq_file *seq; |
2675 | int ret; |
2676 | |
2677 | ret = seq_open(file, &swaps_op); |
2678 | if (ret) |
2679 | return ret; |
2680 | |
2681 | seq = file->private_data; |
2682 | seq->poll_event = atomic_read(&proc_poll_event); |
2683 | return 0; |
2684 | } |
2685 | |
2686 | static const struct file_operations proc_swaps_operations = { |
2687 | .open = swaps_open, |
2688 | .read = seq_read, |
2689 | .llseek = seq_lseek, |
2690 | .release = seq_release, |
2691 | .poll = swaps_poll, |
2692 | }; |
2693 | |
2694 | static int __init procswaps_init(void) |
2695 | { |
2696 | proc_create("swaps" , 0, NULL, &proc_swaps_operations); |
2697 | return 0; |
2698 | } |
2699 | __initcall(procswaps_init); |
2700 | #endif /* CONFIG_PROC_FS */ |
2701 | |
2702 | #ifdef MAX_SWAPFILES_CHECK |
2703 | static int __init max_swapfiles_check(void) |
2704 | { |
2705 | MAX_SWAPFILES_CHECK(); |
2706 | return 0; |
2707 | } |
2708 | late_initcall(max_swapfiles_check); |
2709 | #endif |
2710 | |
2711 | static struct swap_info_struct *alloc_swap_info(void) |
2712 | { |
2713 | struct swap_info_struct *p; |
2714 | unsigned int type; |
2715 | int i; |
2716 | |
2717 | p = kvzalloc(struct_size(p, avail_lists, nr_node_ids), GFP_KERNEL); |
2718 | if (!p) |
2719 | return ERR_PTR(-ENOMEM); |
2720 | |
2721 | spin_lock(&swap_lock); |
2722 | for (type = 0; type < nr_swapfiles; type++) { |
2723 | if (!(swap_info[type]->flags & SWP_USED)) |
2724 | break; |
2725 | } |
2726 | if (type >= MAX_SWAPFILES) { |
2727 | spin_unlock(&swap_lock); |
2728 | kvfree(p); |
2729 | return ERR_PTR(-EPERM); |
2730 | } |
2731 | if (type >= nr_swapfiles) { |
2732 | p->type = type; |
2733 | WRITE_ONCE(swap_info[type], p); |
2734 | /* |
2735 | * Write swap_info[type] before nr_swapfiles, in case a |
2736 | * racing procfs swap_start() or swap_next() is reading them. |
2737 | * (We never shrink nr_swapfiles, we never free this entry.) |
2738 | */ |
2739 | smp_wmb(); |
2740 | WRITE_ONCE(nr_swapfiles, nr_swapfiles + 1); |
2741 | } else { |
2742 | kvfree(p); |
2743 | p = swap_info[type]; |
2744 | /* |
2745 | * Do not memset this entry: a racing procfs swap_next() |
2746 | * would be relying on p->type to remain valid. |
2747 | */ |
2748 | } |
2749 | INIT_LIST_HEAD(&p->first_swap_extent.list); |
2750 | plist_node_init(&p->list, 0); |
2751 | for_each_node(i) |
2752 | plist_node_init(&p->avail_lists[i], 0); |
2753 | p->flags = SWP_USED; |
2754 | spin_unlock(&swap_lock); |
2755 | spin_lock_init(&p->lock); |
2756 | spin_lock_init(&p->cont_lock); |
2757 | |
2758 | return p; |
2759 | } |
2760 | |
2761 | static int claim_swapfile(struct swap_info_struct *p, struct inode *inode) |
2762 | { |
2763 | int error; |
2764 | |
2765 | if (S_ISBLK(inode->i_mode)) { |
2766 | p->bdev = bdgrab(I_BDEV(inode)); |
2767 | error = blkdev_get(p->bdev, |
2768 | FMODE_READ | FMODE_WRITE | FMODE_EXCL, p); |
2769 | if (error < 0) { |
2770 | p->bdev = NULL; |
2771 | return error; |
2772 | } |
2773 | p->old_block_size = block_size(p->bdev); |
2774 | error = set_blocksize(p->bdev, PAGE_SIZE); |
2775 | if (error < 0) |
2776 | return error; |
2777 | p->flags |= SWP_BLKDEV; |
2778 | } else if (S_ISREG(inode->i_mode)) { |
2779 | p->bdev = inode->i_sb->s_bdev; |
2780 | inode_lock(inode); |
2781 | if (IS_SWAPFILE(inode)) |
2782 | return -EBUSY; |
2783 | } else |
2784 | return -EINVAL; |
2785 | |
2786 | return 0; |
2787 | } |
2788 | |
2789 | |
2790 | /* |
2791 | * Find out how many pages are allowed for a single swap device. There |
2792 | * are two limiting factors: |
2793 | * 1) the number of bits for the swap offset in the swp_entry_t type, and |
2794 | * 2) the number of bits in the swap pte, as defined by the different |
2795 | * architectures. |
2796 | * |
2797 | * In order to find the largest possible bit mask, a swap entry with |
2798 | * swap type 0 and swap offset ~0UL is created, encoded to a swap pte, |
2799 | * decoded to a swp_entry_t again, and finally the swap offset is |
2800 | * extracted. |
2801 | * |
2802 | * This will mask all the bits from the initial ~0UL mask that can't |
2803 | * be encoded in either the swp_entry_t or the architecture definition |
2804 | * of a swap pte. |
2805 | */ |
2806 | unsigned long generic_max_swapfile_size(void) |
2807 | { |
2808 | return swp_offset(pte_to_swp_entry( |
2809 | swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1; |
2810 | } |
2811 | |
2812 | /* Can be overridden by an architecture for additional checks. */ |
2813 | __weak unsigned long max_swapfile_size(void) |
2814 | { |
2815 | return generic_max_swapfile_size(); |
2816 | } |
2817 | |
2818 | static unsigned long (struct swap_info_struct *p, |
2819 | union swap_header *, |
2820 | struct inode *inode) |
2821 | { |
2822 | int i; |
2823 | unsigned long maxpages; |
2824 | unsigned long swapfilepages; |
2825 | unsigned long last_page; |
2826 | |
2827 | if (memcmp("SWAPSPACE2" , swap_header->magic.magic, 10)) { |
2828 | pr_err("Unable to find swap-space signature\n" ); |
2829 | return 0; |
2830 | } |
2831 | |
2832 | /* swap partition endianess hack... */ |
2833 | if (swab32(swap_header->info.version) == 1) { |
2834 | swab32s(&swap_header->info.version); |
2835 | swab32s(&swap_header->info.last_page); |
2836 | swab32s(&swap_header->info.nr_badpages); |
2837 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
2838 | return 0; |
2839 | for (i = 0; i < swap_header->info.nr_badpages; i++) |
2840 | swab32s(&swap_header->info.badpages[i]); |
2841 | } |
2842 | /* Check the swap header's sub-version */ |
2843 | if (swap_header->info.version != 1) { |
2844 | pr_warn("Unable to handle swap header version %d\n" , |
2845 | swap_header->info.version); |
2846 | return 0; |
2847 | } |
2848 | |
2849 | p->lowest_bit = 1; |
2850 | p->cluster_next = 1; |
2851 | p->cluster_nr = 0; |
2852 | |
2853 | maxpages = max_swapfile_size(); |
2854 | last_page = swap_header->info.last_page; |
2855 | if (!last_page) { |
2856 | pr_warn("Empty swap-file\n" ); |
2857 | return 0; |
2858 | } |
2859 | if (last_page > maxpages) { |
2860 | pr_warn("Truncating oversized swap area, only using %luk out of %luk\n" , |
2861 | maxpages << (PAGE_SHIFT - 10), |
2862 | last_page << (PAGE_SHIFT - 10)); |
2863 | } |
2864 | if (maxpages > last_page) { |
2865 | maxpages = last_page + 1; |
2866 | /* p->max is an unsigned int: don't overflow it */ |
2867 | if ((unsigned int)maxpages == 0) |
2868 | maxpages = UINT_MAX; |
2869 | } |
2870 | p->highest_bit = maxpages - 1; |
2871 | |
2872 | if (!maxpages) |
2873 | return 0; |
2874 | swapfilepages = i_size_read(inode) >> PAGE_SHIFT; |
2875 | if (swapfilepages && maxpages > swapfilepages) { |
2876 | pr_warn("Swap area shorter than signature indicates\n" ); |
2877 | return 0; |
2878 | } |
2879 | if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) |
2880 | return 0; |
2881 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
2882 | return 0; |
2883 | |
2884 | return maxpages; |
2885 | } |
2886 | |
2887 | #define SWAP_CLUSTER_INFO_COLS \ |
2888 | DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info)) |
2889 | #define SWAP_CLUSTER_SPACE_COLS \ |
2890 | DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER) |
2891 | #define SWAP_CLUSTER_COLS \ |
2892 | max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS) |
2893 | |
2894 | static int setup_swap_map_and_extents(struct swap_info_struct *p, |
2895 | union swap_header *, |
2896 | unsigned char *swap_map, |
2897 | struct swap_cluster_info *cluster_info, |
2898 | unsigned long maxpages, |
2899 | sector_t *span) |
2900 | { |
2901 | unsigned int j, k; |
2902 | unsigned int nr_good_pages; |
2903 | int nr_extents; |
2904 | unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); |
2905 | unsigned long col = p->cluster_next / SWAPFILE_CLUSTER % SWAP_CLUSTER_COLS; |
2906 | unsigned long i, idx; |
2907 | |
2908 | nr_good_pages = maxpages - 1; /* omit header page */ |
2909 | |
2910 | cluster_list_init(&p->free_clusters); |
2911 | cluster_list_init(&p->discard_clusters); |
2912 | |
2913 | for (i = 0; i < swap_header->info.nr_badpages; i++) { |
2914 | unsigned int page_nr = swap_header->info.badpages[i]; |
2915 | if (page_nr == 0 || page_nr > swap_header->info.last_page) |
2916 | return -EINVAL; |
2917 | if (page_nr < maxpages) { |
2918 | swap_map[page_nr] = SWAP_MAP_BAD; |
2919 | nr_good_pages--; |
2920 | /* |
2921 | * Haven't marked the cluster free yet, no list |
2922 | * operation involved |
2923 | */ |
2924 | inc_cluster_info_page(p, cluster_info, page_nr); |
2925 | } |
2926 | } |
2927 | |
2928 | /* Haven't marked the cluster free yet, no list operation involved */ |
2929 | for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++) |
2930 | inc_cluster_info_page(p, cluster_info, i); |
2931 | |
2932 | if (nr_good_pages) { |
2933 | swap_map[0] = SWAP_MAP_BAD; |
2934 | /* |
2935 | * Not mark the cluster free yet, no list |
2936 | * operation involved |
2937 | */ |
2938 | inc_cluster_info_page(p, cluster_info, 0); |
2939 | p->max = maxpages; |
2940 | p->pages = nr_good_pages; |
2941 | nr_extents = setup_swap_extents(p, span); |
2942 | if (nr_extents < 0) |
2943 | return nr_extents; |
2944 | nr_good_pages = p->pages; |
2945 | } |
2946 | if (!nr_good_pages) { |
2947 | pr_warn("Empty swap-file\n" ); |
2948 | return -EINVAL; |
2949 | } |
2950 | |
2951 | if (!cluster_info) |
2952 | return nr_extents; |
2953 | |
2954 | |
2955 | /* |
2956 | * Reduce false cache line sharing between cluster_info and |
2957 | * sharing same address space. |
2958 | */ |
2959 | for (k = 0; k < SWAP_CLUSTER_COLS; k++) { |
2960 | j = (k + col) % SWAP_CLUSTER_COLS; |
2961 | for (i = 0; i < DIV_ROUND_UP(nr_clusters, SWAP_CLUSTER_COLS); i++) { |
2962 | idx = i * SWAP_CLUSTER_COLS + j; |
2963 | if (idx >= nr_clusters) |
2964 | continue; |
2965 | if (cluster_count(&cluster_info[idx])) |
2966 | continue; |
2967 | cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE); |
2968 | cluster_list_add_tail(&p->free_clusters, cluster_info, |
2969 | idx); |
2970 | } |
2971 | } |
2972 | return nr_extents; |
2973 | } |
2974 | |
2975 | /* |
2976 | * Helper to sys_swapon determining if a given swap |
2977 | * backing device queue supports DISCARD operations. |
2978 | */ |
2979 | static bool swap_discardable(struct swap_info_struct *si) |
2980 | { |
2981 | struct request_queue *q = bdev_get_queue(si->bdev); |
2982 | |
2983 | if (!q || !blk_queue_discard(q)) |
2984 | return false; |
2985 | |
2986 | return true; |
2987 | } |
2988 | |
2989 | SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) |
2990 | { |
2991 | struct swap_info_struct *p; |
2992 | struct filename *name; |
2993 | struct file *swap_file = NULL; |
2994 | struct address_space *mapping; |
2995 | int prio; |
2996 | int error; |
2997 | union swap_header *; |
2998 | int nr_extents; |
2999 | sector_t span; |
3000 | unsigned long maxpages; |
3001 | unsigned char *swap_map = NULL; |
3002 | struct swap_cluster_info *cluster_info = NULL; |
3003 | unsigned long *frontswap_map = NULL; |
3004 | struct page *page = NULL; |
3005 | struct inode *inode = NULL; |
3006 | bool inced_nr_rotate_swap = false; |
3007 | |
3008 | if (swap_flags & ~SWAP_FLAGS_VALID) |
3009 | return -EINVAL; |
3010 | |
3011 | if (!capable(CAP_SYS_ADMIN)) |
3012 | return -EPERM; |
3013 | |
3014 | if (!swap_avail_heads) |
3015 | return -ENOMEM; |
3016 | |
3017 | p = alloc_swap_info(); |
3018 | if (IS_ERR(p)) |
3019 | return PTR_ERR(p); |
3020 | |
3021 | INIT_WORK(&p->discard_work, swap_discard_work); |
3022 | |
3023 | name = getname(specialfile); |
3024 | if (IS_ERR(name)) { |
3025 | error = PTR_ERR(name); |
3026 | name = NULL; |
3027 | goto bad_swap; |
3028 | } |
3029 | swap_file = file_open_name(name, O_RDWR|O_LARGEFILE, 0); |
3030 | if (IS_ERR(swap_file)) { |
3031 | error = PTR_ERR(swap_file); |
3032 | swap_file = NULL; |
3033 | goto bad_swap; |
3034 | } |
3035 | |
3036 | p->swap_file = swap_file; |
3037 | mapping = swap_file->f_mapping; |
3038 | inode = mapping->host; |
3039 | |
3040 | /* If S_ISREG(inode->i_mode) will do inode_lock(inode); */ |
3041 | error = claim_swapfile(p, inode); |
3042 | if (unlikely(error)) |
3043 | goto bad_swap; |
3044 | |
3045 | /* |
3046 | * Read the swap header. |
3047 | */ |
3048 | if (!mapping->a_ops->readpage) { |
3049 | error = -EINVAL; |
3050 | goto bad_swap; |
3051 | } |
3052 | page = read_mapping_page(mapping, 0, swap_file); |
3053 | if (IS_ERR(page)) { |
3054 | error = PTR_ERR(page); |
3055 | goto bad_swap; |
3056 | } |
3057 | swap_header = kmap(page); |
3058 | |
3059 | maxpages = read_swap_header(p, swap_header, inode); |
3060 | if (unlikely(!maxpages)) { |
3061 | error = -EINVAL; |
3062 | goto bad_swap; |
3063 | } |
3064 | |
3065 | /* OK, set up the swap map and apply the bad block list */ |
3066 | swap_map = vzalloc(maxpages); |
3067 | if (!swap_map) { |
3068 | error = -ENOMEM; |
3069 | goto bad_swap; |
3070 | } |
3071 | |
3072 | if (bdi_cap_stable_pages_required(inode_to_bdi(inode))) |
3073 | p->flags |= SWP_STABLE_WRITES; |
3074 | |
3075 | if (bdi_cap_synchronous_io(inode_to_bdi(inode))) |
3076 | p->flags |= SWP_SYNCHRONOUS_IO; |
3077 | |
3078 | if (p->bdev && blk_queue_nonrot(bdev_get_queue(p->bdev))) { |
3079 | int cpu; |
3080 | unsigned long ci, nr_cluster; |
3081 | |
3082 | p->flags |= SWP_SOLIDSTATE; |
3083 | /* |
3084 | * select a random position to start with to help wear leveling |
3085 | * SSD |
3086 | */ |
3087 | p->cluster_next = 1 + (prandom_u32() % p->highest_bit); |
3088 | nr_cluster = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); |
3089 | |
3090 | cluster_info = kvcalloc(nr_cluster, sizeof(*cluster_info), |
3091 | GFP_KERNEL); |
3092 | if (!cluster_info) { |
3093 | error = -ENOMEM; |
3094 | goto bad_swap; |
3095 | } |
3096 | |
3097 | for (ci = 0; ci < nr_cluster; ci++) |
3098 | spin_lock_init(&((cluster_info + ci)->lock)); |
3099 | |
3100 | p->percpu_cluster = alloc_percpu(struct percpu_cluster); |
3101 | if (!p->percpu_cluster) { |
3102 | error = -ENOMEM; |
3103 | goto bad_swap; |
3104 | } |
3105 | for_each_possible_cpu(cpu) { |
3106 | struct percpu_cluster *cluster; |
3107 | cluster = per_cpu_ptr(p->percpu_cluster, cpu); |
3108 | cluster_set_null(&cluster->index); |
3109 | } |
3110 | } else { |
3111 | atomic_inc(&nr_rotate_swap); |
3112 | inced_nr_rotate_swap = true; |
3113 | } |
3114 | |
3115 | error = swap_cgroup_swapon(p->type, maxpages); |
3116 | if (error) |
3117 | goto bad_swap; |
3118 | |
3119 | nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map, |
3120 | cluster_info, maxpages, &span); |
3121 | if (unlikely(nr_extents < 0)) { |
3122 | error = nr_extents; |
3123 | goto bad_swap; |
3124 | } |
3125 | /* frontswap enabled? set up bit-per-page map for frontswap */ |
3126 | if (IS_ENABLED(CONFIG_FRONTSWAP)) |
3127 | frontswap_map = kvcalloc(BITS_TO_LONGS(maxpages), |
3128 | sizeof(long), |
3129 | GFP_KERNEL); |
3130 | |
3131 | if (p->bdev &&(swap_flags & SWAP_FLAG_DISCARD) && swap_discardable(p)) { |
3132 | /* |
3133 | * When discard is enabled for swap with no particular |
3134 | * policy flagged, we set all swap discard flags here in |
3135 | * order to sustain backward compatibility with older |
3136 | * swapon(8) releases. |
3137 | */ |
3138 | p->flags |= (SWP_DISCARDABLE | SWP_AREA_DISCARD | |
3139 | SWP_PAGE_DISCARD); |
3140 | |
3141 | /* |
3142 | * By flagging sys_swapon, a sysadmin can tell us to |
3143 | * either do single-time area discards only, or to just |
3144 | * perform discards for released swap page-clusters. |
3145 | * Now it's time to adjust the p->flags accordingly. |
3146 | */ |
3147 | if (swap_flags & SWAP_FLAG_DISCARD_ONCE) |
3148 | p->flags &= ~SWP_PAGE_DISCARD; |
3149 | else if (swap_flags & SWAP_FLAG_DISCARD_PAGES) |
3150 | p->flags &= ~SWP_AREA_DISCARD; |
3151 | |
3152 | /* issue a swapon-time discard if it's still required */ |
3153 | if (p->flags & SWP_AREA_DISCARD) { |
3154 | int err = discard_swap(p); |
3155 | if (unlikely(err)) |
3156 | pr_err("swapon: discard_swap(%p): %d\n" , |
3157 | p, err); |
3158 | } |
3159 | } |
3160 | |
3161 | error = init_swap_address_space(p->type, maxpages); |
3162 | if (error) |
3163 | goto bad_swap; |
3164 | |
3165 | mutex_lock(&swapon_mutex); |
3166 | prio = -1; |
3167 | if (swap_flags & SWAP_FLAG_PREFER) |
3168 | prio = |
3169 | (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT; |
3170 | enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map); |
3171 | |
3172 | pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s%s\n" , |
3173 | p->pages<<(PAGE_SHIFT-10), name->name, p->prio, |
3174 | nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10), |
3175 | (p->flags & SWP_SOLIDSTATE) ? "SS" : "" , |
3176 | (p->flags & SWP_DISCARDABLE) ? "D" : "" , |
3177 | (p->flags & SWP_AREA_DISCARD) ? "s" : "" , |
3178 | (p->flags & SWP_PAGE_DISCARD) ? "c" : "" , |
3179 | (frontswap_map) ? "FS" : "" ); |
3180 | |
3181 | mutex_unlock(&swapon_mutex); |
3182 | atomic_inc(&proc_poll_event); |
3183 | wake_up_interruptible(&proc_poll_wait); |
3184 | |
3185 | if (S_ISREG(inode->i_mode)) |
3186 | inode->i_flags |= S_SWAPFILE; |
3187 | error = 0; |
3188 | goto out; |
3189 | bad_swap: |
3190 | free_percpu(p->percpu_cluster); |
3191 | p->percpu_cluster = NULL; |
3192 | if (inode && S_ISBLK(inode->i_mode) && p->bdev) { |
3193 | set_blocksize(p->bdev, p->old_block_size); |
3194 | blkdev_put(p->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); |
3195 | } |
3196 | destroy_swap_extents(p); |
3197 | swap_cgroup_swapoff(p->type); |
3198 | spin_lock(&swap_lock); |
3199 | p->swap_file = NULL; |
3200 | p->flags = 0; |
3201 | spin_unlock(&swap_lock); |
3202 | vfree(swap_map); |
3203 | kvfree(cluster_info); |
3204 | kvfree(frontswap_map); |
3205 | if (inced_nr_rotate_swap) |
3206 | atomic_dec(&nr_rotate_swap); |
3207 | if (swap_file) { |
3208 | if (inode && S_ISREG(inode->i_mode)) { |
3209 | inode_unlock(inode); |
3210 | inode = NULL; |
3211 | } |
3212 | filp_close(swap_file, NULL); |
3213 | } |
3214 | out: |
3215 | if (page && !IS_ERR(page)) { |
3216 | kunmap(page); |
3217 | put_page(page); |
3218 | } |
3219 | if (name) |
3220 | putname(name); |
3221 | if (inode && S_ISREG(inode->i_mode)) |
3222 | inode_unlock(inode); |
3223 | if (!error) |
3224 | enable_swap_slots_cache(); |
3225 | return error; |
3226 | } |
3227 | |
3228 | void si_swapinfo(struct sysinfo *val) |
3229 | { |
3230 | unsigned int type; |
3231 | unsigned long nr_to_be_unused = 0; |
3232 | |
3233 | spin_lock(&swap_lock); |
3234 | for (type = 0; type < nr_swapfiles; type++) { |
3235 | struct swap_info_struct *si = swap_info[type]; |
3236 | |
3237 | if ((si->flags & SWP_USED) && !(si->flags & SWP_WRITEOK)) |
3238 | nr_to_be_unused += si->inuse_pages; |
3239 | } |
3240 | val->freeswap = atomic_long_read(&nr_swap_pages) + nr_to_be_unused; |
3241 | val->totalswap = total_swap_pages + nr_to_be_unused; |
3242 | spin_unlock(&swap_lock); |
3243 | } |
3244 | |
3245 | /* |
3246 | * Verify that a swap entry is valid and increment its swap map count. |
3247 | * |
3248 | * Returns error code in following case. |
3249 | * - success -> 0 |
3250 | * - swp_entry is invalid -> EINVAL |
3251 | * - swp_entry is migration entry -> EINVAL |
3252 | * - swap-cache reference is requested but there is already one. -> EEXIST |
3253 | * - swap-cache reference is requested but the entry is not used. -> ENOENT |
3254 | * - swap-mapped reference requested but needs continued swap count. -> ENOMEM |
3255 | */ |
3256 | static int __swap_duplicate(swp_entry_t entry, unsigned char usage) |
3257 | { |
3258 | struct swap_info_struct *p; |
3259 | struct swap_cluster_info *ci; |
3260 | unsigned long offset; |
3261 | unsigned char count; |
3262 | unsigned char has_cache; |
3263 | int err = -EINVAL; |
3264 | |
3265 | if (non_swap_entry(entry)) |
3266 | goto out; |
3267 | |
3268 | p = swp_swap_info(entry); |
3269 | if (!p) |
3270 | goto bad_file; |
3271 | |
3272 | offset = swp_offset(entry); |
3273 | if (unlikely(offset >= p->max)) |
3274 | goto out; |
3275 | |
3276 | ci = lock_cluster_or_swap_info(p, offset); |
3277 | |
3278 | count = p->swap_map[offset]; |
3279 | |
3280 | /* |
3281 | * swapin_readahead() doesn't check if a swap entry is valid, so the |
3282 | * swap entry could be SWAP_MAP_BAD. Check here with lock held. |
3283 | */ |
3284 | if (unlikely(swap_count(count) == SWAP_MAP_BAD)) { |
3285 | err = -ENOENT; |
3286 | goto unlock_out; |
3287 | } |
3288 | |
3289 | has_cache = count & SWAP_HAS_CACHE; |
3290 | count &= ~SWAP_HAS_CACHE; |
3291 | err = 0; |
3292 | |
3293 | if (usage == SWAP_HAS_CACHE) { |
3294 | |
3295 | /* set SWAP_HAS_CACHE if there is no cache and entry is used */ |
3296 | if (!has_cache && count) |
3297 | has_cache = SWAP_HAS_CACHE; |
3298 | else if (has_cache) /* someone else added cache */ |
3299 | err = -EEXIST; |
3300 | else /* no users remaining */ |
3301 | err = -ENOENT; |
3302 | |
3303 | } else if (count || has_cache) { |
3304 | |
3305 | if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX) |
3306 | count += usage; |
3307 | else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX) |
3308 | err = -EINVAL; |
3309 | else if (swap_count_continued(p, offset, count)) |
3310 | count = COUNT_CONTINUED; |
3311 | else |
3312 | err = -ENOMEM; |
3313 | } else |
3314 | err = -ENOENT; /* unused swap entry */ |
3315 | |
3316 | p->swap_map[offset] = count | has_cache; |
3317 | |
3318 | unlock_out: |
3319 | unlock_cluster_or_swap_info(p, ci); |
3320 | out: |
3321 | return err; |
3322 | |
3323 | bad_file: |
3324 | pr_err("swap_dup: %s%08lx\n" , Bad_file, entry.val); |
3325 | goto out; |
3326 | } |
3327 | |
3328 | /* |
3329 | * Help swapoff by noting that swap entry belongs to shmem/tmpfs |
3330 | * (in which case its reference count is never incremented). |
3331 | */ |
3332 | void swap_shmem_alloc(swp_entry_t entry) |
3333 | { |
3334 | __swap_duplicate(entry, SWAP_MAP_SHMEM); |
3335 | } |
3336 | |
3337 | /* |
3338 | * Increase reference count of swap entry by 1. |
3339 | * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required |
3340 | * but could not be atomically allocated. Returns 0, just as if it succeeded, |
3341 | * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which |
3342 | * might occur if a page table entry has got corrupted. |
3343 | */ |
3344 | int swap_duplicate(swp_entry_t entry) |
3345 | { |
3346 | int err = 0; |
3347 | |
3348 | while (!err && __swap_duplicate(entry, 1) == -ENOMEM) |
3349 | err = add_swap_count_continuation(entry, GFP_ATOMIC); |
3350 | return err; |
3351 | } |
3352 | |
3353 | /* |
3354 | * @entry: swap entry for which we allocate swap cache. |
3355 | * |
3356 | * Called when allocating swap cache for existing swap entry, |
3357 | * This can return error codes. Returns 0 at success. |
3358 | * -EBUSY means there is a swap cache. |
3359 | * Note: return code is different from swap_duplicate(). |
3360 | */ |
3361 | int swapcache_prepare(swp_entry_t entry) |
3362 | { |
3363 | return __swap_duplicate(entry, SWAP_HAS_CACHE); |
3364 | } |
3365 | |
3366 | struct swap_info_struct *swp_swap_info(swp_entry_t entry) |
3367 | { |
3368 | return swap_type_to_swap_info(swp_type(entry)); |
3369 | } |
3370 | |
3371 | struct swap_info_struct *page_swap_info(struct page *page) |
3372 | { |
3373 | swp_entry_t entry = { .val = page_private(page) }; |
3374 | return swp_swap_info(entry); |
3375 | } |
3376 | |
3377 | /* |
3378 | * out-of-line __page_file_ methods to avoid include hell. |
3379 | */ |
3380 | struct address_space *__page_file_mapping(struct page *page) |
3381 | { |
3382 | return page_swap_info(page)->swap_file->f_mapping; |
3383 | } |
3384 | EXPORT_SYMBOL_GPL(__page_file_mapping); |
3385 | |
3386 | pgoff_t __page_file_index(struct page *page) |
3387 | { |
3388 | swp_entry_t swap = { .val = page_private(page) }; |
3389 | return swp_offset(swap); |
3390 | } |
3391 | EXPORT_SYMBOL_GPL(__page_file_index); |
3392 | |
3393 | /* |
3394 | * add_swap_count_continuation - called when a swap count is duplicated |
3395 | * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's |
3396 | * page of the original vmalloc'ed swap_map, to hold the continuation count |
3397 | * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called |
3398 | * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc. |
3399 | * |
3400 | * These continuation pages are seldom referenced: the common paths all work |
3401 | * on the original swap_map, only referring to a continuation page when the |
3402 | * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX. |
3403 | * |
3404 | * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding |
3405 | * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL) |
3406 | * can be called after dropping locks. |
3407 | */ |
3408 | int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask) |
3409 | { |
3410 | struct swap_info_struct *si; |
3411 | struct swap_cluster_info *ci; |
3412 | struct page *head; |
3413 | struct page *page; |
3414 | struct page *list_page; |
3415 | pgoff_t offset; |
3416 | unsigned char count; |
3417 | |
3418 | /* |
3419 | * When debugging, it's easier to use __GFP_ZERO here; but it's better |
3420 | * for latency not to zero a page while GFP_ATOMIC and holding locks. |
3421 | */ |
3422 | page = alloc_page(gfp_mask | __GFP_HIGHMEM); |
3423 | |
3424 | si = swap_info_get(entry); |
3425 | if (!si) { |
3426 | /* |
3427 | * An acceptable race has occurred since the failing |
3428 | * __swap_duplicate(): the swap entry has been freed, |
3429 | * perhaps even the whole swap_map cleared for swapoff. |
3430 | */ |
3431 | goto outer; |
3432 | } |
3433 | |
3434 | offset = swp_offset(entry); |
3435 | |
3436 | ci = lock_cluster(si, offset); |
3437 | |
3438 | count = si->swap_map[offset] & ~SWAP_HAS_CACHE; |
3439 | |
3440 | if ((count & ~COUNT_CONTINUED) != SWAP_MAP_MAX) { |
3441 | /* |
3442 | * The higher the swap count, the more likely it is that tasks |
3443 | * will race to add swap count continuation: we need to avoid |
3444 | * over-provisioning. |
3445 | */ |
3446 | goto out; |
3447 | } |
3448 | |
3449 | if (!page) { |
3450 | unlock_cluster(ci); |
3451 | spin_unlock(&si->lock); |
3452 | return -ENOMEM; |
3453 | } |
3454 | |
3455 | /* |
3456 | * We are fortunate that although vmalloc_to_page uses pte_offset_map, |
3457 | * no architecture is using highmem pages for kernel page tables: so it |
3458 | * will not corrupt the GFP_ATOMIC caller's atomic page table kmaps. |
3459 | */ |
3460 | head = vmalloc_to_page(si->swap_map + offset); |
3461 | offset &= ~PAGE_MASK; |
3462 | |
3463 | spin_lock(&si->cont_lock); |
3464 | /* |
3465 | * Page allocation does not initialize the page's lru field, |
3466 | * but it does always reset its private field. |
3467 | */ |
3468 | if (!page_private(head)) { |
3469 | BUG_ON(count & COUNT_CONTINUED); |
3470 | INIT_LIST_HEAD(&head->lru); |
3471 | set_page_private(head, SWP_CONTINUED); |
3472 | si->flags |= SWP_CONTINUED; |
3473 | } |
3474 | |
3475 | list_for_each_entry(list_page, &head->lru, lru) { |
3476 | unsigned char *map; |
3477 | |
3478 | /* |
3479 | * If the previous map said no continuation, but we've found |
3480 | * a continuation page, free our allocation and use this one. |
3481 | */ |
3482 | if (!(count & COUNT_CONTINUED)) |
3483 | goto out_unlock_cont; |
3484 | |
3485 | map = kmap_atomic(list_page) + offset; |
3486 | count = *map; |
3487 | kunmap_atomic(map); |
3488 | |
3489 | /* |
3490 | * If this continuation count now has some space in it, |
3491 | * free our allocation and use this one. |
3492 | */ |
3493 | if ((count & ~COUNT_CONTINUED) != SWAP_CONT_MAX) |
3494 | goto out_unlock_cont; |
3495 | } |
3496 | |
3497 | list_add_tail(&page->lru, &head->lru); |
3498 | page = NULL; /* now it's attached, don't free it */ |
3499 | out_unlock_cont: |
3500 | spin_unlock(&si->cont_lock); |
3501 | out: |
3502 | unlock_cluster(ci); |
3503 | spin_unlock(&si->lock); |
3504 | outer: |
3505 | if (page) |
3506 | __free_page(page); |
3507 | return 0; |
3508 | } |
3509 | |
3510 | /* |
3511 | * swap_count_continued - when the original swap_map count is incremented |
3512 | * from SWAP_MAP_MAX, check if there is already a continuation page to carry |
3513 | * into, carry if so, or else fail until a new continuation page is allocated; |
3514 | * when the original swap_map count is decremented from 0 with continuation, |
3515 | * borrow from the continuation and report whether it still holds more. |
3516 | * Called while __swap_duplicate() or swap_entry_free() holds swap or cluster |
3517 | * lock. |
3518 | */ |
3519 | static bool swap_count_continued(struct swap_info_struct *si, |
3520 | pgoff_t offset, unsigned char count) |
3521 | { |
3522 | struct page *head; |
3523 | struct page *page; |
3524 | unsigned char *map; |
3525 | bool ret; |
3526 | |
3527 | head = vmalloc_to_page(si->swap_map + offset); |
3528 | if (page_private(head) != SWP_CONTINUED) { |
3529 | BUG_ON(count & COUNT_CONTINUED); |
3530 | return false; /* need to add count continuation */ |
3531 | } |
3532 | |
3533 | spin_lock(&si->cont_lock); |
3534 | offset &= ~PAGE_MASK; |
3535 | page = list_entry(head->lru.next, struct page, lru); |
3536 | map = kmap_atomic(page) + offset; |
3537 | |
3538 | if (count == SWAP_MAP_MAX) /* initial increment from swap_map */ |
3539 | goto init_map; /* jump over SWAP_CONT_MAX checks */ |
3540 | |
3541 | if (count == (SWAP_MAP_MAX | COUNT_CONTINUED)) { /* incrementing */ |
3542 | /* |
3543 | * Think of how you add 1 to 999 |
3544 | */ |
3545 | while (*map == (SWAP_CONT_MAX | COUNT_CONTINUED)) { |
3546 | kunmap_atomic(map); |
3547 | page = list_entry(page->lru.next, struct page, lru); |
3548 | BUG_ON(page == head); |
3549 | map = kmap_atomic(page) + offset; |
3550 | } |
3551 | if (*map == SWAP_CONT_MAX) { |
3552 | kunmap_atomic(map); |
3553 | page = list_entry(page->lru.next, struct page, lru); |
3554 | if (page == head) { |
3555 | ret = false; /* add count continuation */ |
3556 | goto out; |
3557 | } |
3558 | map = kmap_atomic(page) + offset; |
3559 | init_map: *map = 0; /* we didn't zero the page */ |
3560 | } |
3561 | *map += 1; |
3562 | kunmap_atomic(map); |
3563 | page = list_entry(page->lru.prev, struct page, lru); |
3564 | while (page != head) { |
3565 | map = kmap_atomic(page) + offset; |
3566 | *map = COUNT_CONTINUED; |
3567 | kunmap_atomic(map); |
3568 | page = list_entry(page->lru.prev, struct page, lru); |
3569 | } |
3570 | ret = true; /* incremented */ |
3571 | |
3572 | } else { /* decrementing */ |
3573 | /* |
3574 | * Think of how you subtract 1 from 1000 |
3575 | */ |
3576 | BUG_ON(count != COUNT_CONTINUED); |
3577 | while (*map == COUNT_CONTINUED) { |
3578 | kunmap_atomic(map); |
3579 | page = |
---|