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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * z3fold.c
4 *
5 * Author: Vitaly Wool <vitaly.wool@konsulko.com>
6 * Copyright (C) 2016, Sony Mobile Communications Inc.
7 *
8 * This implementation is based on zbud written by Seth Jennings.
9 *
10 * z3fold is an special purpose allocator for storing compressed pages. It
11 * can store up to three compressed pages per page which improves the
12 * compression ratio of zbud while retaining its main concepts (e. g. always
13 * storing an integral number of objects per page) and simplicity.
14 * It still has simple and deterministic reclaim properties that make it
15 * preferable to a higher density approach (with no requirement on integral
16 * number of object per page) when reclaim is used.
17 *
18 * As in zbud, pages are divided into "chunks". The size of the chunks is
19 * fixed at compile time and is determined by NCHUNKS_ORDER below.
20 *
21 * z3fold doesn't export any API and is meant to be used via zpool API.
22 */
23
24#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
25
26#include <linux/atomic.h>
27#include <linux/sched.h>
28#include <linux/cpumask.h>
29#include <linux/list.h>
30#include <linux/mm.h>
31#include <linux/module.h>
32#include <linux/page-flags.h>
33#include <linux/migrate.h>
34#include <linux/node.h>
35#include <linux/compaction.h>
36#include <linux/percpu.h>
37#include <linux/preempt.h>
38#include <linux/workqueue.h>
39#include <linux/slab.h>
40#include <linux/spinlock.h>
41#include <linux/zpool.h>
42#include <linux/kmemleak.h>
43
44/*
45 * NCHUNKS_ORDER determines the internal allocation granularity, effectively
46 * adjusting internal fragmentation. It also determines the number of
47 * freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the
48 * allocation granularity will be in chunks of size PAGE_SIZE/64. Some chunks
49 * in the beginning of an allocated page are occupied by z3fold header, so
50 * NCHUNKS will be calculated to 63 (or 62 in case CONFIG_DEBUG_SPINLOCK=y),
51 * which shows the max number of free chunks in z3fold page, also there will
52 * be 63, or 62, respectively, freelists per pool.
53 */
54#define NCHUNKS_ORDER 6
55
56#define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER)
57#define CHUNK_SIZE (1 << CHUNK_SHIFT)
58#define ZHDR_SIZE_ALIGNED round_up(sizeof(struct z3fold_header), CHUNK_SIZE)
59#define ZHDR_CHUNKS (ZHDR_SIZE_ALIGNED >> CHUNK_SHIFT)
60#define TOTAL_CHUNKS (PAGE_SIZE >> CHUNK_SHIFT)
61#define NCHUNKS (TOTAL_CHUNKS - ZHDR_CHUNKS)
62
63#define BUDDY_MASK (0x3)
64#define BUDDY_SHIFT 2
65#define SLOTS_ALIGN (0x40)
66
67/*****************
68 * Structures
69*****************/
70struct z3fold_pool;
71
72enum buddy {
73 HEADLESS = 0,
74 FIRST,
75 MIDDLE,
76 LAST,
77 BUDDIES_MAX = LAST
78};
79
80struct z3fold_buddy_slots {
81 /*
82 * we are using BUDDY_MASK in handle_to_buddy etc. so there should
83 * be enough slots to hold all possible variants
84 */
85 unsigned long slot[BUDDY_MASK + 1];
86 unsigned long pool; /* back link */
87 rwlock_t lock;
88};
89#define HANDLE_FLAG_MASK (0x03)
90
91/*
92 * struct z3fold_header - z3fold page metadata occupying first chunks of each
93 * z3fold page, except for HEADLESS pages
94 * @buddy: links the z3fold page into the relevant list in the
95 * pool
96 * @page_lock: per-page lock
97 * @refcount: reference count for the z3fold page
98 * @work: work_struct for page layout optimization
99 * @slots: pointer to the structure holding buddy slots
100 * @pool: pointer to the containing pool
101 * @cpu: CPU which this page "belongs" to
102 * @first_chunks: the size of the first buddy in chunks, 0 if free
103 * @middle_chunks: the size of the middle buddy in chunks, 0 if free
104 * @last_chunks: the size of the last buddy in chunks, 0 if free
105 * @first_num: the starting number (for the first handle)
106 * @mapped_count: the number of objects currently mapped
107 */
108struct z3fold_header {
109 struct list_head buddy;
110 spinlock_t page_lock;
111 struct kref refcount;
112 struct work_struct work;
113 struct z3fold_buddy_slots *slots;
114 struct z3fold_pool *pool;
115 short cpu;
116 unsigned short first_chunks;
117 unsigned short middle_chunks;
118 unsigned short last_chunks;
119 unsigned short start_middle;
120 unsigned short first_num:2;
121 unsigned short mapped_count:2;
122 unsigned short foreign_handles:2;
123};
124
125/**
126 * struct z3fold_pool - stores metadata for each z3fold pool
127 * @name: pool name
128 * @lock: protects pool unbuddied lists
129 * @stale_lock: protects pool stale page list
130 * @unbuddied: per-cpu array of lists tracking z3fold pages that contain 2-
131 * buddies; the list each z3fold page is added to depends on
132 * the size of its free region.
133 * @stale: list of pages marked for freeing
134 * @pages_nr: number of z3fold pages in the pool.
135 * @c_handle: cache for z3fold_buddy_slots allocation
136 * @compact_wq: workqueue for page layout background optimization
137 * @release_wq: workqueue for safe page release
138 * @work: work_struct for safe page release
139 *
140 * This structure is allocated at pool creation time and maintains metadata
141 * pertaining to a particular z3fold pool.
142 */
143struct z3fold_pool {
144 const char *name;
145 spinlock_t lock;
146 spinlock_t stale_lock;
147 struct list_head __percpu *unbuddied;
148 struct list_head stale;
149 atomic64_t pages_nr;
150 struct kmem_cache *c_handle;
151 struct workqueue_struct *compact_wq;
152 struct workqueue_struct *release_wq;
153 struct work_struct work;
154};
155
156/*
157 * Internal z3fold page flags
158 */
159enum z3fold_page_flags {
160 PAGE_HEADLESS = 0,
161 MIDDLE_CHUNK_MAPPED,
162 NEEDS_COMPACTING,
163 PAGE_STALE,
164 PAGE_CLAIMED, /* by either reclaim or free */
165 PAGE_MIGRATED, /* page is migrated and soon to be released */
166};
167
168/*
169 * handle flags, go under HANDLE_FLAG_MASK
170 */
171enum z3fold_handle_flags {
172 HANDLES_NOFREE = 0,
173};
174
175/*
176 * Forward declarations
177 */
178static struct z3fold_header *__z3fold_alloc(struct z3fold_pool *, size_t, bool);
179static void compact_page_work(struct work_struct *w);
180
181/*****************
182 * Helpers
183*****************/
184
185/* Converts an allocation size in bytes to size in z3fold chunks */
186static int size_to_chunks(size_t size)
187{
188 return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
189}
190
191#define for_each_unbuddied_list(_iter, _begin) \
192 for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++)
193
194static inline struct z3fold_buddy_slots *alloc_slots(struct z3fold_pool *pool,
195 gfp_t gfp)
196{
197 struct z3fold_buddy_slots *slots = kmem_cache_zalloc(pool->c_handle,
198 gfp);
199
200 if (slots) {
201 /* It will be freed separately in free_handle(). */
202 kmemleak_not_leak(slots);
203 slots->pool = (unsigned long)pool;
204 rwlock_init(&slots->lock);
205 }
206
207 return slots;
208}
209
210static inline struct z3fold_pool *slots_to_pool(struct z3fold_buddy_slots *s)
211{
212 return (struct z3fold_pool *)(s->pool & ~HANDLE_FLAG_MASK);
213}
214
215static inline struct z3fold_buddy_slots *handle_to_slots(unsigned long handle)
216{
217 return (struct z3fold_buddy_slots *)(handle & ~(SLOTS_ALIGN - 1));
218}
219
220/* Lock a z3fold page */
221static inline void z3fold_page_lock(struct z3fold_header *zhdr)
222{
223 spin_lock(&zhdr->page_lock);
224}
225
226/* Try to lock a z3fold page */
227static inline int z3fold_page_trylock(struct z3fold_header *zhdr)
228{
229 return spin_trylock(&zhdr->page_lock);
230}
231
232/* Unlock a z3fold page */
233static inline void z3fold_page_unlock(struct z3fold_header *zhdr)
234{
235 spin_unlock(&zhdr->page_lock);
236}
237
238/* return locked z3fold page if it's not headless */
239static inline struct z3fold_header *get_z3fold_header(unsigned long handle)
240{
241 struct z3fold_buddy_slots *slots;
242 struct z3fold_header *zhdr;
243 int locked = 0;
244
245 if (!(handle & (1 << PAGE_HEADLESS))) {
246 slots = handle_to_slots(handle);
247 do {
248 unsigned long addr;
249
250 read_lock(&slots->lock);
251 addr = *(unsigned long *)handle;
252 zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
253 locked = z3fold_page_trylock(zhdr);
254 read_unlock(&slots->lock);
255 if (locked) {
256 struct page *page = virt_to_page(zhdr);
257
258 if (!test_bit(PAGE_MIGRATED, &page->private))
259 break;
260 z3fold_page_unlock(zhdr);
261 }
262 cpu_relax();
263 } while (true);
264 } else {
265 zhdr = (struct z3fold_header *)(handle & PAGE_MASK);
266 }
267
268 return zhdr;
269}
270
271static inline void put_z3fold_header(struct z3fold_header *zhdr)
272{
273 struct page *page = virt_to_page(zhdr);
274
275 if (!test_bit(PAGE_HEADLESS, &page->private))
276 z3fold_page_unlock(zhdr);
277}
278
279static inline void free_handle(unsigned long handle, struct z3fold_header *zhdr)
280{
281 struct z3fold_buddy_slots *slots;
282 int i;
283 bool is_free;
284
285 if (WARN_ON(*(unsigned long *)handle == 0))
286 return;
287
288 slots = handle_to_slots(handle);
289 write_lock(&slots->lock);
290 *(unsigned long *)handle = 0;
291
292 if (test_bit(HANDLES_NOFREE, &slots->pool)) {
293 write_unlock(&slots->lock);
294 return; /* simple case, nothing else to do */
295 }
296
297 if (zhdr->slots != slots)
298 zhdr->foreign_handles--;
299
300 is_free = true;
301 for (i = 0; i <= BUDDY_MASK; i++) {
302 if (slots->slot[i]) {
303 is_free = false;
304 break;
305 }
306 }
307 write_unlock(&slots->lock);
308
309 if (is_free) {
310 struct z3fold_pool *pool = slots_to_pool(slots);
311
312 if (zhdr->slots == slots)
313 zhdr->slots = NULL;
314 kmem_cache_free(pool->c_handle, slots);
315 }
316}
317
318/* Initializes the z3fold header of a newly allocated z3fold page */
319static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
320 struct z3fold_pool *pool, gfp_t gfp)
321{
322 struct z3fold_header *zhdr = page_address(page);
323 struct z3fold_buddy_slots *slots;
324
325 clear_bit(PAGE_HEADLESS, &page->private);
326 clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
327 clear_bit(NEEDS_COMPACTING, &page->private);
328 clear_bit(PAGE_STALE, &page->private);
329 clear_bit(PAGE_CLAIMED, &page->private);
330 clear_bit(PAGE_MIGRATED, &page->private);
331 if (headless)
332 return zhdr;
333
334 slots = alloc_slots(pool, gfp);
335 if (!slots)
336 return NULL;
337
338 memset(zhdr, 0, sizeof(*zhdr));
339 spin_lock_init(&zhdr->page_lock);
340 kref_init(&zhdr->refcount);
341 zhdr->cpu = -1;
342 zhdr->slots = slots;
343 zhdr->pool = pool;
344 INIT_LIST_HEAD(&zhdr->buddy);
345 INIT_WORK(&zhdr->work, compact_page_work);
346 return zhdr;
347}
348
349/* Resets the struct page fields and frees the page */
350static void free_z3fold_page(struct page *page, bool headless)
351{
352 if (!headless) {
353 lock_page(page);
354 __ClearPageMovable(page);
355 unlock_page(page);
356 }
357 __free_page(page);
358}
359
360/* Helper function to build the index */
361static inline int __idx(struct z3fold_header *zhdr, enum buddy bud)
362{
363 return (bud + zhdr->first_num) & BUDDY_MASK;
364}
365
366/*
367 * Encodes the handle of a particular buddy within a z3fold page.
368 * Zhdr->page_lock should be held as this function accesses first_num
369 * if bud != HEADLESS.
370 */
371static unsigned long __encode_handle(struct z3fold_header *zhdr,
372 struct z3fold_buddy_slots *slots,
373 enum buddy bud)
374{
375 unsigned long h = (unsigned long)zhdr;
376 int idx = 0;
377
378 /*
379 * For a headless page, its handle is its pointer with the extra
380 * PAGE_HEADLESS bit set
381 */
382 if (bud == HEADLESS)
383 return h | (1 << PAGE_HEADLESS);
384
385 /* otherwise, return pointer to encoded handle */
386 idx = __idx(zhdr, bud);
387 h += idx;
388 if (bud == LAST)
389 h |= (zhdr->last_chunks << BUDDY_SHIFT);
390
391 write_lock(&slots->lock);
392 slots->slot[idx] = h;
393 write_unlock(&slots->lock);
394 return (unsigned long)&slots->slot[idx];
395}
396
397static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud)
398{
399 return __encode_handle(zhdr, zhdr->slots, bud);
400}
401
402/* only for LAST bud, returns zero otherwise */
403static unsigned short handle_to_chunks(unsigned long handle)
404{
405 struct z3fold_buddy_slots *slots = handle_to_slots(handle);
406 unsigned long addr;
407
408 read_lock(&slots->lock);
409 addr = *(unsigned long *)handle;
410 read_unlock(&slots->lock);
411 return (addr & ~PAGE_MASK) >> BUDDY_SHIFT;
412}
413
414/*
415 * (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle
416 * but that doesn't matter. because the masking will result in the
417 * correct buddy number.
418 */
419static enum buddy handle_to_buddy(unsigned long handle)
420{
421 struct z3fold_header *zhdr;
422 struct z3fold_buddy_slots *slots = handle_to_slots(handle);
423 unsigned long addr;
424
425 read_lock(&slots->lock);
426 WARN_ON(handle & (1 << PAGE_HEADLESS));
427 addr = *(unsigned long *)handle;
428 read_unlock(&slots->lock);
429 zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
430 return (addr - zhdr->first_num) & BUDDY_MASK;
431}
432
433static inline struct z3fold_pool *zhdr_to_pool(struct z3fold_header *zhdr)
434{
435 return zhdr->pool;
436}
437
438static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked)
439{
440 struct page *page = virt_to_page(zhdr);
441 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
442
443 WARN_ON(!list_empty(&zhdr->buddy));
444 set_bit(PAGE_STALE, &page->private);
445 clear_bit(NEEDS_COMPACTING, &page->private);
446 spin_lock(&pool->lock);
447 spin_unlock(&pool->lock);
448
449 if (locked)
450 z3fold_page_unlock(zhdr);
451
452 spin_lock(&pool->stale_lock);
453 list_add(&zhdr->buddy, &pool->stale);
454 queue_work(pool->release_wq, &pool->work);
455 spin_unlock(&pool->stale_lock);
456
457 atomic64_dec(&pool->pages_nr);
458}
459
460static void release_z3fold_page_locked(struct kref *ref)
461{
462 struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
463 refcount);
464 WARN_ON(z3fold_page_trylock(zhdr));
465 __release_z3fold_page(zhdr, true);
466}
467
468static void release_z3fold_page_locked_list(struct kref *ref)
469{
470 struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
471 refcount);
472 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
473
474 spin_lock(&pool->lock);
475 list_del_init(&zhdr->buddy);
476 spin_unlock(&pool->lock);
477
478 WARN_ON(z3fold_page_trylock(zhdr));
479 __release_z3fold_page(zhdr, true);
480}
481
482static inline int put_z3fold_locked(struct z3fold_header *zhdr)
483{
484 return kref_put(&zhdr->refcount, release_z3fold_page_locked);
485}
486
487static inline int put_z3fold_locked_list(struct z3fold_header *zhdr)
488{
489 return kref_put(&zhdr->refcount, release_z3fold_page_locked_list);
490}
491
492static void free_pages_work(struct work_struct *w)
493{
494 struct z3fold_pool *pool = container_of(w, struct z3fold_pool, work);
495
496 spin_lock(&pool->stale_lock);
497 while (!list_empty(&pool->stale)) {
498 struct z3fold_header *zhdr = list_first_entry(&pool->stale,
499 struct z3fold_header, buddy);
500 struct page *page = virt_to_page(zhdr);
501
502 list_del(&zhdr->buddy);
503 if (WARN_ON(!test_bit(PAGE_STALE, &page->private)))
504 continue;
505 spin_unlock(&pool->stale_lock);
506 cancel_work_sync(&zhdr->work);
507 free_z3fold_page(page, false);
508 cond_resched();
509 spin_lock(&pool->stale_lock);
510 }
511 spin_unlock(&pool->stale_lock);
512}
513
514/*
515 * Returns the number of free chunks in a z3fold page.
516 * NB: can't be used with HEADLESS pages.
517 */
518static int num_free_chunks(struct z3fold_header *zhdr)
519{
520 int nfree;
521 /*
522 * If there is a middle object, pick up the bigger free space
523 * either before or after it. Otherwise just subtract the number
524 * of chunks occupied by the first and the last objects.
525 */
526 if (zhdr->middle_chunks != 0) {
527 int nfree_before = zhdr->first_chunks ?
528 0 : zhdr->start_middle - ZHDR_CHUNKS;
529 int nfree_after = zhdr->last_chunks ?
530 0 : TOTAL_CHUNKS -
531 (zhdr->start_middle + zhdr->middle_chunks);
532 nfree = max(nfree_before, nfree_after);
533 } else
534 nfree = NCHUNKS - zhdr->first_chunks - zhdr->last_chunks;
535 return nfree;
536}
537
538/* Add to the appropriate unbuddied list */
539static inline void add_to_unbuddied(struct z3fold_pool *pool,
540 struct z3fold_header *zhdr)
541{
542 if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 ||
543 zhdr->middle_chunks == 0) {
544 struct list_head *unbuddied;
545 int freechunks = num_free_chunks(zhdr);
546
547 migrate_disable();
548 unbuddied = this_cpu_ptr(pool->unbuddied);
549 spin_lock(&pool->lock);
550 list_add(&zhdr->buddy, &unbuddied[freechunks]);
551 spin_unlock(&pool->lock);
552 zhdr->cpu = smp_processor_id();
553 migrate_enable();
554 }
555}
556
557static inline enum buddy get_free_buddy(struct z3fold_header *zhdr, int chunks)
558{
559 enum buddy bud = HEADLESS;
560
561 if (zhdr->middle_chunks) {
562 if (!zhdr->first_chunks &&
563 chunks <= zhdr->start_middle - ZHDR_CHUNKS)
564 bud = FIRST;
565 else if (!zhdr->last_chunks)
566 bud = LAST;
567 } else {
568 if (!zhdr->first_chunks)
569 bud = FIRST;
570 else if (!zhdr->last_chunks)
571 bud = LAST;
572 else
573 bud = MIDDLE;
574 }
575
576 return bud;
577}
578
579static inline void *mchunk_memmove(struct z3fold_header *zhdr,
580 unsigned short dst_chunk)
581{
582 void *beg = zhdr;
583 return memmove(beg + (dst_chunk << CHUNK_SHIFT),
584 beg + (zhdr->start_middle << CHUNK_SHIFT),
585 zhdr->middle_chunks << CHUNK_SHIFT);
586}
587
588static inline bool buddy_single(struct z3fold_header *zhdr)
589{
590 return !((zhdr->first_chunks && zhdr->middle_chunks) ||
591 (zhdr->first_chunks && zhdr->last_chunks) ||
592 (zhdr->middle_chunks && zhdr->last_chunks));
593}
594
595static struct z3fold_header *compact_single_buddy(struct z3fold_header *zhdr)
596{
597 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
598 void *p = zhdr;
599 unsigned long old_handle = 0;
600 size_t sz = 0;
601 struct z3fold_header *new_zhdr = NULL;
602 int first_idx = __idx(zhdr, FIRST);
603 int middle_idx = __idx(zhdr, MIDDLE);
604 int last_idx = __idx(zhdr, LAST);
605 unsigned short *moved_chunks = NULL;
606
607 /*
608 * No need to protect slots here -- all the slots are "local" and
609 * the page lock is already taken
610 */
611 if (zhdr->first_chunks && zhdr->slots->slot[first_idx]) {
612 p += ZHDR_SIZE_ALIGNED;
613 sz = zhdr->first_chunks << CHUNK_SHIFT;
614 old_handle = (unsigned long)&zhdr->slots->slot[first_idx];
615 moved_chunks = &zhdr->first_chunks;
616 } else if (zhdr->middle_chunks && zhdr->slots->slot[middle_idx]) {
617 p += zhdr->start_middle << CHUNK_SHIFT;
618 sz = zhdr->middle_chunks << CHUNK_SHIFT;
619 old_handle = (unsigned long)&zhdr->slots->slot[middle_idx];
620 moved_chunks = &zhdr->middle_chunks;
621 } else if (zhdr->last_chunks && zhdr->slots->slot[last_idx]) {
622 p += PAGE_SIZE - (zhdr->last_chunks << CHUNK_SHIFT);
623 sz = zhdr->last_chunks << CHUNK_SHIFT;
624 old_handle = (unsigned long)&zhdr->slots->slot[last_idx];
625 moved_chunks = &zhdr->last_chunks;
626 }
627
628 if (sz > 0) {
629 enum buddy new_bud = HEADLESS;
630 short chunks = size_to_chunks(sz);
631 void *q;
632
633 new_zhdr = __z3fold_alloc(pool, sz, false);
634 if (!new_zhdr)
635 return NULL;
636
637 if (WARN_ON(new_zhdr == zhdr))
638 goto out_fail;
639
640 new_bud = get_free_buddy(new_zhdr, chunks);
641 q = new_zhdr;
642 switch (new_bud) {
643 case FIRST:
644 new_zhdr->first_chunks = chunks;
645 q += ZHDR_SIZE_ALIGNED;
646 break;
647 case MIDDLE:
648 new_zhdr->middle_chunks = chunks;
649 new_zhdr->start_middle =
650 new_zhdr->first_chunks + ZHDR_CHUNKS;
651 q += new_zhdr->start_middle << CHUNK_SHIFT;
652 break;
653 case LAST:
654 new_zhdr->last_chunks = chunks;
655 q += PAGE_SIZE - (new_zhdr->last_chunks << CHUNK_SHIFT);
656 break;
657 default:
658 goto out_fail;
659 }
660 new_zhdr->foreign_handles++;
661 memcpy(q, p, sz);
662 write_lock(&zhdr->slots->lock);
663 *(unsigned long *)old_handle = (unsigned long)new_zhdr +
664 __idx(new_zhdr, new_bud);
665 if (new_bud == LAST)
666 *(unsigned long *)old_handle |=
667 (new_zhdr->last_chunks << BUDDY_SHIFT);
668 write_unlock(&zhdr->slots->lock);
669 add_to_unbuddied(pool, new_zhdr);
670 z3fold_page_unlock(new_zhdr);
671
672 *moved_chunks = 0;
673 }
674
675 return new_zhdr;
676
677out_fail:
678 if (new_zhdr && !put_z3fold_locked(new_zhdr)) {
679 add_to_unbuddied(pool, new_zhdr);
680 z3fold_page_unlock(new_zhdr);
681 }
682 return NULL;
683
684}
685
686#define BIG_CHUNK_GAP 3
687/* Has to be called with lock held */
688static int z3fold_compact_page(struct z3fold_header *zhdr)
689{
690 struct page *page = virt_to_page(zhdr);
691
692 if (test_bit(MIDDLE_CHUNK_MAPPED, &page->private))
693 return 0; /* can't move middle chunk, it's used */
694
695 if (unlikely(PageIsolated(page)))
696 return 0;
697
698 if (zhdr->middle_chunks == 0)
699 return 0; /* nothing to compact */
700
701 if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
702 /* move to the beginning */
703 mchunk_memmove(zhdr, ZHDR_CHUNKS);
704 zhdr->first_chunks = zhdr->middle_chunks;
705 zhdr->middle_chunks = 0;
706 zhdr->start_middle = 0;
707 zhdr->first_num++;
708 return 1;
709 }
710
711 /*
712 * moving data is expensive, so let's only do that if
713 * there's substantial gain (at least BIG_CHUNK_GAP chunks)
714 */
715 if (zhdr->first_chunks != 0 && zhdr->last_chunks == 0 &&
716 zhdr->start_middle - (zhdr->first_chunks + ZHDR_CHUNKS) >=
717 BIG_CHUNK_GAP) {
718 mchunk_memmove(zhdr, zhdr->first_chunks + ZHDR_CHUNKS);
719 zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
720 return 1;
721 } else if (zhdr->last_chunks != 0 && zhdr->first_chunks == 0 &&
722 TOTAL_CHUNKS - (zhdr->last_chunks + zhdr->start_middle
723 + zhdr->middle_chunks) >=
724 BIG_CHUNK_GAP) {
725 unsigned short new_start = TOTAL_CHUNKS - zhdr->last_chunks -
726 zhdr->middle_chunks;
727 mchunk_memmove(zhdr, new_start);
728 zhdr->start_middle = new_start;
729 return 1;
730 }
731
732 return 0;
733}
734
735static void do_compact_page(struct z3fold_header *zhdr, bool locked)
736{
737 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
738 struct page *page;
739
740 page = virt_to_page(zhdr);
741 if (locked)
742 WARN_ON(z3fold_page_trylock(zhdr));
743 else
744 z3fold_page_lock(zhdr);
745 if (WARN_ON(!test_and_clear_bit(NEEDS_COMPACTING, &page->private))) {
746 z3fold_page_unlock(zhdr);
747 return;
748 }
749 spin_lock(&pool->lock);
750 list_del_init(&zhdr->buddy);
751 spin_unlock(&pool->lock);
752
753 if (put_z3fold_locked(zhdr))
754 return;
755
756 if (test_bit(PAGE_STALE, &page->private) ||
757 test_and_set_bit(PAGE_CLAIMED, &page->private)) {
758 z3fold_page_unlock(zhdr);
759 return;
760 }
761
762 if (!zhdr->foreign_handles && buddy_single(zhdr) &&
763 zhdr->mapped_count == 0 && compact_single_buddy(zhdr)) {
764 if (!put_z3fold_locked(zhdr)) {
765 clear_bit(PAGE_CLAIMED, &page->private);
766 z3fold_page_unlock(zhdr);
767 }
768 return;
769 }
770
771 z3fold_compact_page(zhdr);
772 add_to_unbuddied(pool, zhdr);
773 clear_bit(PAGE_CLAIMED, &page->private);
774 z3fold_page_unlock(zhdr);
775}
776
777static void compact_page_work(struct work_struct *w)
778{
779 struct z3fold_header *zhdr = container_of(w, struct z3fold_header,
780 work);
781
782 do_compact_page(zhdr, false);
783}
784
785/* returns _locked_ z3fold page header or NULL */
786static inline struct z3fold_header *__z3fold_alloc(struct z3fold_pool *pool,
787 size_t size, bool can_sleep)
788{
789 struct z3fold_header *zhdr = NULL;
790 struct page *page;
791 struct list_head *unbuddied;
792 int chunks = size_to_chunks(size), i;
793
794lookup:
795 migrate_disable();
796 /* First, try to find an unbuddied z3fold page. */
797 unbuddied = this_cpu_ptr(pool->unbuddied);
798 for_each_unbuddied_list(i, chunks) {
799 struct list_head *l = &unbuddied[i];
800
801 zhdr = list_first_entry_or_null(READ_ONCE(l),
802 struct z3fold_header, buddy);
803
804 if (!zhdr)
805 continue;
806
807 /* Re-check under lock. */
808 spin_lock(&pool->lock);
809 if (unlikely(zhdr != list_first_entry(READ_ONCE(l),
810 struct z3fold_header, buddy)) ||
811 !z3fold_page_trylock(zhdr)) {
812 spin_unlock(&pool->lock);
813 zhdr = NULL;
814 migrate_enable();
815 if (can_sleep)
816 cond_resched();
817 goto lookup;
818 }
819 list_del_init(&zhdr->buddy);
820 zhdr->cpu = -1;
821 spin_unlock(&pool->lock);
822
823 page = virt_to_page(zhdr);
824 if (test_bit(NEEDS_COMPACTING, &page->private) ||
825 test_bit(PAGE_CLAIMED, &page->private)) {
826 z3fold_page_unlock(zhdr);
827 zhdr = NULL;
828 migrate_enable();
829 if (can_sleep)
830 cond_resched();
831 goto lookup;
832 }
833
834 /*
835 * this page could not be removed from its unbuddied
836 * list while pool lock was held, and then we've taken
837 * page lock so kref_put could not be called before
838 * we got here, so it's safe to just call kref_get()
839 */
840 kref_get(&zhdr->refcount);
841 break;
842 }
843 migrate_enable();
844
845 if (!zhdr) {
846 int cpu;
847
848 /* look for _exact_ match on other cpus' lists */
849 for_each_online_cpu(cpu) {
850 struct list_head *l;
851
852 unbuddied = per_cpu_ptr(pool->unbuddied, cpu);
853 spin_lock(&pool->lock);
854 l = &unbuddied[chunks];
855
856 zhdr = list_first_entry_or_null(READ_ONCE(l),
857 struct z3fold_header, buddy);
858
859 if (!zhdr || !z3fold_page_trylock(zhdr)) {
860 spin_unlock(&pool->lock);
861 zhdr = NULL;
862 continue;
863 }
864 list_del_init(&zhdr->buddy);
865 zhdr->cpu = -1;
866 spin_unlock(&pool->lock);
867
868 page = virt_to_page(zhdr);
869 if (test_bit(NEEDS_COMPACTING, &page->private) ||
870 test_bit(PAGE_CLAIMED, &page->private)) {
871 z3fold_page_unlock(zhdr);
872 zhdr = NULL;
873 if (can_sleep)
874 cond_resched();
875 continue;
876 }
877 kref_get(&zhdr->refcount);
878 break;
879 }
880 }
881
882 if (zhdr && !zhdr->slots) {
883 zhdr->slots = alloc_slots(pool, GFP_ATOMIC);
884 if (!zhdr->slots)
885 goto out_fail;
886 }
887 return zhdr;
888
889out_fail:
890 if (!put_z3fold_locked(zhdr)) {
891 add_to_unbuddied(pool, zhdr);
892 z3fold_page_unlock(zhdr);
893 }
894 return NULL;
895}
896
897/*
898 * API Functions
899 */
900
901/**
902 * z3fold_create_pool() - create a new z3fold pool
903 * @name: pool name
904 * @gfp: gfp flags when allocating the z3fold pool structure
905 *
906 * Return: pointer to the new z3fold pool or NULL if the metadata allocation
907 * failed.
908 */
909static struct z3fold_pool *z3fold_create_pool(const char *name, gfp_t gfp)
910{
911 struct z3fold_pool *pool = NULL;
912 int i, cpu;
913
914 pool = kzalloc(sizeof(struct z3fold_pool), gfp);
915 if (!pool)
916 goto out;
917 pool->c_handle = kmem_cache_create("z3fold_handle",
918 sizeof(struct z3fold_buddy_slots),
919 SLOTS_ALIGN, 0, NULL);
920 if (!pool->c_handle)
921 goto out_c;
922 spin_lock_init(&pool->lock);
923 spin_lock_init(&pool->stale_lock);
924 pool->unbuddied = __alloc_percpu(sizeof(struct list_head) * NCHUNKS,
925 __alignof__(struct list_head));
926 if (!pool->unbuddied)
927 goto out_pool;
928 for_each_possible_cpu(cpu) {
929 struct list_head *unbuddied =
930 per_cpu_ptr(pool->unbuddied, cpu);
931 for_each_unbuddied_list(i, 0)
932 INIT_LIST_HEAD(&unbuddied[i]);
933 }
934 INIT_LIST_HEAD(&pool->stale);
935 atomic64_set(&pool->pages_nr, 0);
936 pool->name = name;
937 pool->compact_wq = create_singlethread_workqueue(pool->name);
938 if (!pool->compact_wq)
939 goto out_unbuddied;
940 pool->release_wq = create_singlethread_workqueue(pool->name);
941 if (!pool->release_wq)
942 goto out_wq;
943 INIT_WORK(&pool->work, free_pages_work);
944 return pool;
945
946out_wq:
947 destroy_workqueue(pool->compact_wq);
948out_unbuddied:
949 free_percpu(pool->unbuddied);
950out_pool:
951 kmem_cache_destroy(pool->c_handle);
952out_c:
953 kfree(pool);
954out:
955 return NULL;
956}
957
958/**
959 * z3fold_destroy_pool() - destroys an existing z3fold pool
960 * @pool: the z3fold pool to be destroyed
961 *
962 * The pool should be emptied before this function is called.
963 */
964static void z3fold_destroy_pool(struct z3fold_pool *pool)
965{
966 kmem_cache_destroy(pool->c_handle);
967
968 /*
969 * We need to destroy pool->compact_wq before pool->release_wq,
970 * as any pending work on pool->compact_wq will call
971 * queue_work(pool->release_wq, &pool->work).
972 *
973 * There are still outstanding pages until both workqueues are drained,
974 * so we cannot unregister migration until then.
975 */
976
977 destroy_workqueue(pool->compact_wq);
978 destroy_workqueue(pool->release_wq);
979 free_percpu(pool->unbuddied);
980 kfree(pool);
981}
982
983static const struct movable_operations z3fold_mops;
984
985/**
986 * z3fold_alloc() - allocates a region of a given size
987 * @pool: z3fold pool from which to allocate
988 * @size: size in bytes of the desired allocation
989 * @gfp: gfp flags used if the pool needs to grow
990 * @handle: handle of the new allocation
991 *
992 * This function will attempt to find a free region in the pool large enough to
993 * satisfy the allocation request. A search of the unbuddied lists is
994 * performed first. If no suitable free region is found, then a new page is
995 * allocated and added to the pool to satisfy the request.
996 *
997 * Return: 0 if success and handle is set, otherwise -EINVAL if the size or
998 * gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
999 * a new page.
1000 */
1001static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
1002 unsigned long *handle)
1003{
1004 int chunks = size_to_chunks(size);
1005 struct z3fold_header *zhdr = NULL;
1006 struct page *page = NULL;
1007 enum buddy bud;
1008 bool can_sleep = gfpflags_allow_blocking(gfp);
1009
1010 if (!size || (gfp & __GFP_HIGHMEM))
1011 return -EINVAL;
1012
1013 if (size > PAGE_SIZE)
1014 return -ENOSPC;
1015
1016 if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
1017 bud = HEADLESS;
1018 else {
1019retry:
1020 zhdr = __z3fold_alloc(pool, size, can_sleep);
1021 if (zhdr) {
1022 bud = get_free_buddy(zhdr, chunks);
1023 if (bud == HEADLESS) {
1024 if (!put_z3fold_locked(zhdr))
1025 z3fold_page_unlock(zhdr);
1026 pr_err("No free chunks in unbuddied\n");
1027 WARN_ON(1);
1028 goto retry;
1029 }
1030 page = virt_to_page(zhdr);
1031 goto found;
1032 }
1033 bud = FIRST;
1034 }
1035
1036 page = alloc_page(gfp);
1037 if (!page)
1038 return -ENOMEM;
1039
1040 zhdr = init_z3fold_page(page, bud == HEADLESS, pool, gfp);
1041 if (!zhdr) {
1042 __free_page(page);
1043 return -ENOMEM;
1044 }
1045 atomic64_inc(&pool->pages_nr);
1046
1047 if (bud == HEADLESS) {
1048 set_bit(PAGE_HEADLESS, &page->private);
1049 goto headless;
1050 }
1051 if (can_sleep) {
1052 lock_page(page);
1053 __SetPageMovable(page, &z3fold_mops);
1054 unlock_page(page);
1055 } else {
1056 WARN_ON(!trylock_page(page));
1057 __SetPageMovable(page, &z3fold_mops);
1058 unlock_page(page);
1059 }
1060 z3fold_page_lock(zhdr);
1061
1062found:
1063 if (bud == FIRST)
1064 zhdr->first_chunks = chunks;
1065 else if (bud == LAST)
1066 zhdr->last_chunks = chunks;
1067 else {
1068 zhdr->middle_chunks = chunks;
1069 zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
1070 }
1071 add_to_unbuddied(pool, zhdr);
1072
1073headless:
1074 spin_lock(&pool->lock);
1075 *handle = encode_handle(zhdr, bud);
1076 spin_unlock(&pool->lock);
1077 if (bud != HEADLESS)
1078 z3fold_page_unlock(zhdr);
1079
1080 return 0;
1081}
1082
1083/**
1084 * z3fold_free() - frees the allocation associated with the given handle
1085 * @pool: pool in which the allocation resided
1086 * @handle: handle associated with the allocation returned by z3fold_alloc()
1087 *
1088 * In the case that the z3fold page in which the allocation resides is under
1089 * reclaim, as indicated by the PAGE_CLAIMED flag being set, this function
1090 * only sets the first|middle|last_chunks to 0. The page is actually freed
1091 * once all buddies are evicted (see z3fold_reclaim_page() below).
1092 */
1093static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
1094{
1095 struct z3fold_header *zhdr;
1096 struct page *page;
1097 enum buddy bud;
1098 bool page_claimed;
1099
1100 zhdr = get_z3fold_header(handle);
1101 page = virt_to_page(zhdr);
1102 page_claimed = test_and_set_bit(PAGE_CLAIMED, &page->private);
1103
1104 if (test_bit(PAGE_HEADLESS, &page->private)) {
1105 /* if a headless page is under reclaim, just leave.
1106 * NB: we use test_and_set_bit for a reason: if the bit
1107 * has not been set before, we release this page
1108 * immediately so we don't care about its value any more.
1109 */
1110 if (!page_claimed) {
1111 put_z3fold_header(zhdr);
1112 free_z3fold_page(page, true);
1113 atomic64_dec(&pool->pages_nr);
1114 }
1115 return;
1116 }
1117
1118 /* Non-headless case */
1119 bud = handle_to_buddy(handle);
1120
1121 switch (bud) {
1122 case FIRST:
1123 zhdr->first_chunks = 0;
1124 break;
1125 case MIDDLE:
1126 zhdr->middle_chunks = 0;
1127 break;
1128 case LAST:
1129 zhdr->last_chunks = 0;
1130 break;
1131 default:
1132 pr_err("%s: unknown bud %d\n", __func__, bud);
1133 WARN_ON(1);
1134 put_z3fold_header(zhdr);
1135 return;
1136 }
1137
1138 if (!page_claimed)
1139 free_handle(handle, zhdr);
1140 if (put_z3fold_locked_list(zhdr))
1141 return;
1142 if (page_claimed) {
1143 /* the page has not been claimed by us */
1144 put_z3fold_header(zhdr);
1145 return;
1146 }
1147 if (test_and_set_bit(NEEDS_COMPACTING, &page->private)) {
1148 clear_bit(PAGE_CLAIMED, &page->private);
1149 put_z3fold_header(zhdr);
1150 return;
1151 }
1152 if (zhdr->cpu < 0 || !cpu_online(zhdr->cpu)) {
1153 zhdr->cpu = -1;
1154 kref_get(&zhdr->refcount);
1155 clear_bit(PAGE_CLAIMED, &page->private);
1156 do_compact_page(zhdr, true);
1157 return;
1158 }
1159 kref_get(&zhdr->refcount);
1160 clear_bit(PAGE_CLAIMED, &page->private);
1161 queue_work_on(zhdr->cpu, pool->compact_wq, &zhdr->work);
1162 put_z3fold_header(zhdr);
1163}
1164
1165/**
1166 * z3fold_map() - maps the allocation associated with the given handle
1167 * @pool: pool in which the allocation resides
1168 * @handle: handle associated with the allocation to be mapped
1169 *
1170 * Extracts the buddy number from handle and constructs the pointer to the
1171 * correct starting chunk within the page.
1172 *
1173 * Returns: a pointer to the mapped allocation
1174 */
1175static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle)
1176{
1177 struct z3fold_header *zhdr;
1178 struct page *page;
1179 void *addr;
1180 enum buddy buddy;
1181
1182 zhdr = get_z3fold_header(handle);
1183 addr = zhdr;
1184 page = virt_to_page(zhdr);
1185
1186 if (test_bit(PAGE_HEADLESS, &page->private))
1187 goto out;
1188
1189 buddy = handle_to_buddy(handle);
1190 switch (buddy) {
1191 case FIRST:
1192 addr += ZHDR_SIZE_ALIGNED;
1193 break;
1194 case MIDDLE:
1195 addr += zhdr->start_middle << CHUNK_SHIFT;
1196 set_bit(MIDDLE_CHUNK_MAPPED, &page->private);
1197 break;
1198 case LAST:
1199 addr += PAGE_SIZE - (handle_to_chunks(handle) << CHUNK_SHIFT);
1200 break;
1201 default:
1202 pr_err("unknown buddy id %d\n", buddy);
1203 WARN_ON(1);
1204 addr = NULL;
1205 break;
1206 }
1207
1208 if (addr)
1209 zhdr->mapped_count++;
1210out:
1211 put_z3fold_header(zhdr);
1212 return addr;
1213}
1214
1215/**
1216 * z3fold_unmap() - unmaps the allocation associated with the given handle
1217 * @pool: pool in which the allocation resides
1218 * @handle: handle associated with the allocation to be unmapped
1219 */
1220static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle)
1221{
1222 struct z3fold_header *zhdr;
1223 struct page *page;
1224 enum buddy buddy;
1225
1226 zhdr = get_z3fold_header(handle);
1227 page = virt_to_page(zhdr);
1228
1229 if (test_bit(PAGE_HEADLESS, &page->private))
1230 return;
1231
1232 buddy = handle_to_buddy(handle);
1233 if (buddy == MIDDLE)
1234 clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
1235 zhdr->mapped_count--;
1236 put_z3fold_header(zhdr);
1237}
1238
1239/**
1240 * z3fold_get_pool_pages() - gets the z3fold pool size in pages
1241 * @pool: pool whose size is being queried
1242 *
1243 * Returns: size in pages of the given pool.
1244 */
1245static u64 z3fold_get_pool_pages(struct z3fold_pool *pool)
1246{
1247 return atomic64_read(&pool->pages_nr);
1248}
1249
1250static bool z3fold_page_isolate(struct page *page, isolate_mode_t mode)
1251{
1252 struct z3fold_header *zhdr;
1253 struct z3fold_pool *pool;
1254
1255 VM_BUG_ON_PAGE(PageIsolated(page), page);
1256
1257 if (test_bit(PAGE_HEADLESS, &page->private))
1258 return false;
1259
1260 zhdr = page_address(page);
1261 z3fold_page_lock(zhdr);
1262 if (test_bit(NEEDS_COMPACTING, &page->private) ||
1263 test_bit(PAGE_STALE, &page->private))
1264 goto out;
1265
1266 if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0)
1267 goto out;
1268
1269 if (test_and_set_bit(PAGE_CLAIMED, &page->private))
1270 goto out;
1271 pool = zhdr_to_pool(zhdr);
1272 spin_lock(&pool->lock);
1273 if (!list_empty(&zhdr->buddy))
1274 list_del_init(&zhdr->buddy);
1275 spin_unlock(&pool->lock);
1276
1277 kref_get(&zhdr->refcount);
1278 z3fold_page_unlock(zhdr);
1279 return true;
1280
1281out:
1282 z3fold_page_unlock(zhdr);
1283 return false;
1284}
1285
1286static int z3fold_page_migrate(struct page *newpage, struct page *page,
1287 enum migrate_mode mode)
1288{
1289 struct z3fold_header *zhdr, *new_zhdr;
1290 struct z3fold_pool *pool;
1291
1292 VM_BUG_ON_PAGE(!PageIsolated(page), page);
1293 VM_BUG_ON_PAGE(!test_bit(PAGE_CLAIMED, &page->private), page);
1294 VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
1295
1296 zhdr = page_address(page);
1297 pool = zhdr_to_pool(zhdr);
1298
1299 if (!z3fold_page_trylock(zhdr))
1300 return -EAGAIN;
1301 if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0) {
1302 clear_bit(PAGE_CLAIMED, &page->private);
1303 z3fold_page_unlock(zhdr);
1304 return -EBUSY;
1305 }
1306 if (work_pending(&zhdr->work)) {
1307 z3fold_page_unlock(zhdr);
1308 return -EAGAIN;
1309 }
1310 new_zhdr = page_address(newpage);
1311 memcpy(new_zhdr, zhdr, PAGE_SIZE);
1312 newpage->private = page->private;
1313 set_bit(PAGE_MIGRATED, &page->private);
1314 z3fold_page_unlock(zhdr);
1315 spin_lock_init(&new_zhdr->page_lock);
1316 INIT_WORK(&new_zhdr->work, compact_page_work);
1317 /*
1318 * z3fold_page_isolate() ensures that new_zhdr->buddy is empty,
1319 * so we only have to reinitialize it.
1320 */
1321 INIT_LIST_HEAD(&new_zhdr->buddy);
1322 __ClearPageMovable(page);
1323
1324 get_page(newpage);
1325 z3fold_page_lock(new_zhdr);
1326 if (new_zhdr->first_chunks)
1327 encode_handle(new_zhdr, FIRST);
1328 if (new_zhdr->last_chunks)
1329 encode_handle(new_zhdr, LAST);
1330 if (new_zhdr->middle_chunks)
1331 encode_handle(new_zhdr, MIDDLE);
1332 set_bit(NEEDS_COMPACTING, &newpage->private);
1333 new_zhdr->cpu = smp_processor_id();
1334 __SetPageMovable(newpage, &z3fold_mops);
1335 z3fold_page_unlock(new_zhdr);
1336
1337 queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work);
1338
1339 /* PAGE_CLAIMED and PAGE_MIGRATED are cleared now. */
1340 page->private = 0;
1341 put_page(page);
1342 return 0;
1343}
1344
1345static void z3fold_page_putback(struct page *page)
1346{
1347 struct z3fold_header *zhdr;
1348 struct z3fold_pool *pool;
1349
1350 zhdr = page_address(page);
1351 pool = zhdr_to_pool(zhdr);
1352
1353 z3fold_page_lock(zhdr);
1354 if (!list_empty(&zhdr->buddy))
1355 list_del_init(&zhdr->buddy);
1356 INIT_LIST_HEAD(&page->lru);
1357 if (put_z3fold_locked(zhdr))
1358 return;
1359 if (list_empty(&zhdr->buddy))
1360 add_to_unbuddied(pool, zhdr);
1361 clear_bit(PAGE_CLAIMED, &page->private);
1362 z3fold_page_unlock(zhdr);
1363}
1364
1365static const struct movable_operations z3fold_mops = {
1366 .isolate_page = z3fold_page_isolate,
1367 .migrate_page = z3fold_page_migrate,
1368 .putback_page = z3fold_page_putback,
1369};
1370
1371/*****************
1372 * zpool
1373 ****************/
1374
1375static void *z3fold_zpool_create(const char *name, gfp_t gfp)
1376{
1377 return z3fold_create_pool(name, gfp);
1378}
1379
1380static void z3fold_zpool_destroy(void *pool)
1381{
1382 z3fold_destroy_pool(pool);
1383}
1384
1385static int z3fold_zpool_malloc(void *pool, size_t size, gfp_t gfp,
1386 unsigned long *handle)
1387{
1388 return z3fold_alloc(pool, size, gfp, handle);
1389}
1390static void z3fold_zpool_free(void *pool, unsigned long handle)
1391{
1392 z3fold_free(pool, handle);
1393}
1394
1395static void *z3fold_zpool_map(void *pool, unsigned long handle,
1396 enum zpool_mapmode mm)
1397{
1398 return z3fold_map(pool, handle);
1399}
1400static void z3fold_zpool_unmap(void *pool, unsigned long handle)
1401{
1402 z3fold_unmap(pool, handle);
1403}
1404
1405static u64 z3fold_zpool_total_pages(void *pool)
1406{
1407 return z3fold_get_pool_pages(pool);
1408}
1409
1410static struct zpool_driver z3fold_zpool_driver = {
1411 .type = "z3fold",
1412 .sleep_mapped = true,
1413 .owner = THIS_MODULE,
1414 .create = z3fold_zpool_create,
1415 .destroy = z3fold_zpool_destroy,
1416 .malloc = z3fold_zpool_malloc,
1417 .free = z3fold_zpool_free,
1418 .map = z3fold_zpool_map,
1419 .unmap = z3fold_zpool_unmap,
1420 .total_pages = z3fold_zpool_total_pages,
1421};
1422
1423MODULE_ALIAS("zpool-z3fold");
1424
1425static int __init init_z3fold(void)
1426{
1427 /*
1428 * Make sure the z3fold header is not larger than the page size and
1429 * there has remaining spaces for its buddy.
1430 */
1431 BUILD_BUG_ON(ZHDR_SIZE_ALIGNED > PAGE_SIZE - CHUNK_SIZE);
1432 zpool_register_driver(&z3fold_zpool_driver);
1433
1434 return 0;
1435}
1436
1437static void __exit exit_z3fold(void)
1438{
1439 zpool_unregister_driver(&z3fold_zpool_driver);
1440}
1441
1442module_init(init_z3fold);
1443module_exit(exit_z3fold);
1444
1445MODULE_LICENSE("GPL");
1446MODULE_AUTHOR("Vitaly Wool <vitalywool@gmail.com>");
1447MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages");
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * z3fold.c
4 *
5 * Author: Vitaly Wool <vitaly.wool@konsulko.com>
6 * Copyright (C) 2016, Sony Mobile Communications Inc.
7 *
8 * This implementation is based on zbud written by Seth Jennings.
9 *
10 * z3fold is an special purpose allocator for storing compressed pages. It
11 * can store up to three compressed pages per page which improves the
12 * compression ratio of zbud while retaining its main concepts (e. g. always
13 * storing an integral number of objects per page) and simplicity.
14 * It still has simple and deterministic reclaim properties that make it
15 * preferable to a higher density approach (with no requirement on integral
16 * number of object per page) when reclaim is used.
17 *
18 * As in zbud, pages are divided into "chunks". The size of the chunks is
19 * fixed at compile time and is determined by NCHUNKS_ORDER below.
20 *
21 * z3fold doesn't export any API and is meant to be used via zpool API.
22 */
23
24#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
25
26#include <linux/atomic.h>
27#include <linux/sched.h>
28#include <linux/cpumask.h>
29#include <linux/list.h>
30#include <linux/mm.h>
31#include <linux/module.h>
32#include <linux/page-flags.h>
33#include <linux/migrate.h>
34#include <linux/node.h>
35#include <linux/compaction.h>
36#include <linux/percpu.h>
37#include <linux/preempt.h>
38#include <linux/workqueue.h>
39#include <linux/slab.h>
40#include <linux/spinlock.h>
41#include <linux/zpool.h>
42#include <linux/kmemleak.h>
43
44/*
45 * NCHUNKS_ORDER determines the internal allocation granularity, effectively
46 * adjusting internal fragmentation. It also determines the number of
47 * freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the
48 * allocation granularity will be in chunks of size PAGE_SIZE/64. Some chunks
49 * in the beginning of an allocated page are occupied by z3fold header, so
50 * NCHUNKS will be calculated to 63 (or 62 in case CONFIG_DEBUG_SPINLOCK=y),
51 * which shows the max number of free chunks in z3fold page, also there will
52 * be 63, or 62, respectively, freelists per pool.
53 */
54#define NCHUNKS_ORDER 6
55
56#define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER)
57#define CHUNK_SIZE (1 << CHUNK_SHIFT)
58#define ZHDR_SIZE_ALIGNED round_up(sizeof(struct z3fold_header), CHUNK_SIZE)
59#define ZHDR_CHUNKS (ZHDR_SIZE_ALIGNED >> CHUNK_SHIFT)
60#define TOTAL_CHUNKS (PAGE_SIZE >> CHUNK_SHIFT)
61#define NCHUNKS (TOTAL_CHUNKS - ZHDR_CHUNKS)
62
63#define BUDDY_MASK (0x3)
64#define BUDDY_SHIFT 2
65#define SLOTS_ALIGN (0x40)
66
67/*****************
68 * Structures
69*****************/
70struct z3fold_pool;
71
72enum buddy {
73 HEADLESS = 0,
74 FIRST,
75 MIDDLE,
76 LAST,
77 BUDDIES_MAX = LAST
78};
79
80struct z3fold_buddy_slots {
81 /*
82 * we are using BUDDY_MASK in handle_to_buddy etc. so there should
83 * be enough slots to hold all possible variants
84 */
85 unsigned long slot[BUDDY_MASK + 1];
86 unsigned long pool; /* back link */
87 rwlock_t lock;
88};
89#define HANDLE_FLAG_MASK (0x03)
90
91/*
92 * struct z3fold_header - z3fold page metadata occupying first chunks of each
93 * z3fold page, except for HEADLESS pages
94 * @buddy: links the z3fold page into the relevant list in the
95 * pool
96 * @page_lock: per-page lock
97 * @refcount: reference count for the z3fold page
98 * @work: work_struct for page layout optimization
99 * @slots: pointer to the structure holding buddy slots
100 * @pool: pointer to the containing pool
101 * @cpu: CPU which this page "belongs" to
102 * @first_chunks: the size of the first buddy in chunks, 0 if free
103 * @middle_chunks: the size of the middle buddy in chunks, 0 if free
104 * @last_chunks: the size of the last buddy in chunks, 0 if free
105 * @first_num: the starting number (for the first handle)
106 * @mapped_count: the number of objects currently mapped
107 */
108struct z3fold_header {
109 struct list_head buddy;
110 spinlock_t page_lock;
111 struct kref refcount;
112 struct work_struct work;
113 struct z3fold_buddy_slots *slots;
114 struct z3fold_pool *pool;
115 short cpu;
116 unsigned short first_chunks;
117 unsigned short middle_chunks;
118 unsigned short last_chunks;
119 unsigned short start_middle;
120 unsigned short first_num:2;
121 unsigned short mapped_count:2;
122 unsigned short foreign_handles:2;
123};
124
125/**
126 * struct z3fold_pool - stores metadata for each z3fold pool
127 * @name: pool name
128 * @lock: protects pool unbuddied lists
129 * @stale_lock: protects pool stale page list
130 * @unbuddied: per-cpu array of lists tracking z3fold pages that contain 2-
131 * buddies; the list each z3fold page is added to depends on
132 * the size of its free region.
133 * @stale: list of pages marked for freeing
134 * @pages_nr: number of z3fold pages in the pool.
135 * @c_handle: cache for z3fold_buddy_slots allocation
136 * @compact_wq: workqueue for page layout background optimization
137 * @release_wq: workqueue for safe page release
138 * @work: work_struct for safe page release
139 *
140 * This structure is allocated at pool creation time and maintains metadata
141 * pertaining to a particular z3fold pool.
142 */
143struct z3fold_pool {
144 const char *name;
145 spinlock_t lock;
146 spinlock_t stale_lock;
147 struct list_head *unbuddied;
148 struct list_head stale;
149 atomic64_t pages_nr;
150 struct kmem_cache *c_handle;
151 struct workqueue_struct *compact_wq;
152 struct workqueue_struct *release_wq;
153 struct work_struct work;
154};
155
156/*
157 * Internal z3fold page flags
158 */
159enum z3fold_page_flags {
160 PAGE_HEADLESS = 0,
161 MIDDLE_CHUNK_MAPPED,
162 NEEDS_COMPACTING,
163 PAGE_STALE,
164 PAGE_CLAIMED, /* by either reclaim or free */
165 PAGE_MIGRATED, /* page is migrated and soon to be released */
166};
167
168/*
169 * handle flags, go under HANDLE_FLAG_MASK
170 */
171enum z3fold_handle_flags {
172 HANDLES_NOFREE = 0,
173};
174
175/*
176 * Forward declarations
177 */
178static struct z3fold_header *__z3fold_alloc(struct z3fold_pool *, size_t, bool);
179static void compact_page_work(struct work_struct *w);
180
181/*****************
182 * Helpers
183*****************/
184
185/* Converts an allocation size in bytes to size in z3fold chunks */
186static int size_to_chunks(size_t size)
187{
188 return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
189}
190
191#define for_each_unbuddied_list(_iter, _begin) \
192 for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++)
193
194static inline struct z3fold_buddy_slots *alloc_slots(struct z3fold_pool *pool,
195 gfp_t gfp)
196{
197 struct z3fold_buddy_slots *slots = kmem_cache_zalloc(pool->c_handle,
198 gfp);
199
200 if (slots) {
201 /* It will be freed separately in free_handle(). */
202 kmemleak_not_leak(slots);
203 slots->pool = (unsigned long)pool;
204 rwlock_init(&slots->lock);
205 }
206
207 return slots;
208}
209
210static inline struct z3fold_pool *slots_to_pool(struct z3fold_buddy_slots *s)
211{
212 return (struct z3fold_pool *)(s->pool & ~HANDLE_FLAG_MASK);
213}
214
215static inline struct z3fold_buddy_slots *handle_to_slots(unsigned long handle)
216{
217 return (struct z3fold_buddy_slots *)(handle & ~(SLOTS_ALIGN - 1));
218}
219
220/* Lock a z3fold page */
221static inline void z3fold_page_lock(struct z3fold_header *zhdr)
222{
223 spin_lock(&zhdr->page_lock);
224}
225
226/* Try to lock a z3fold page */
227static inline int z3fold_page_trylock(struct z3fold_header *zhdr)
228{
229 return spin_trylock(&zhdr->page_lock);
230}
231
232/* Unlock a z3fold page */
233static inline void z3fold_page_unlock(struct z3fold_header *zhdr)
234{
235 spin_unlock(&zhdr->page_lock);
236}
237
238/* return locked z3fold page if it's not headless */
239static inline struct z3fold_header *get_z3fold_header(unsigned long handle)
240{
241 struct z3fold_buddy_slots *slots;
242 struct z3fold_header *zhdr;
243 int locked = 0;
244
245 if (!(handle & (1 << PAGE_HEADLESS))) {
246 slots = handle_to_slots(handle);
247 do {
248 unsigned long addr;
249
250 read_lock(&slots->lock);
251 addr = *(unsigned long *)handle;
252 zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
253 locked = z3fold_page_trylock(zhdr);
254 read_unlock(&slots->lock);
255 if (locked) {
256 struct page *page = virt_to_page(zhdr);
257
258 if (!test_bit(PAGE_MIGRATED, &page->private))
259 break;
260 z3fold_page_unlock(zhdr);
261 }
262 cpu_relax();
263 } while (true);
264 } else {
265 zhdr = (struct z3fold_header *)(handle & PAGE_MASK);
266 }
267
268 return zhdr;
269}
270
271static inline void put_z3fold_header(struct z3fold_header *zhdr)
272{
273 struct page *page = virt_to_page(zhdr);
274
275 if (!test_bit(PAGE_HEADLESS, &page->private))
276 z3fold_page_unlock(zhdr);
277}
278
279static inline void free_handle(unsigned long handle, struct z3fold_header *zhdr)
280{
281 struct z3fold_buddy_slots *slots;
282 int i;
283 bool is_free;
284
285 if (WARN_ON(*(unsigned long *)handle == 0))
286 return;
287
288 slots = handle_to_slots(handle);
289 write_lock(&slots->lock);
290 *(unsigned long *)handle = 0;
291
292 if (test_bit(HANDLES_NOFREE, &slots->pool)) {
293 write_unlock(&slots->lock);
294 return; /* simple case, nothing else to do */
295 }
296
297 if (zhdr->slots != slots)
298 zhdr->foreign_handles--;
299
300 is_free = true;
301 for (i = 0; i <= BUDDY_MASK; i++) {
302 if (slots->slot[i]) {
303 is_free = false;
304 break;
305 }
306 }
307 write_unlock(&slots->lock);
308
309 if (is_free) {
310 struct z3fold_pool *pool = slots_to_pool(slots);
311
312 if (zhdr->slots == slots)
313 zhdr->slots = NULL;
314 kmem_cache_free(pool->c_handle, slots);
315 }
316}
317
318/* Initializes the z3fold header of a newly allocated z3fold page */
319static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
320 struct z3fold_pool *pool, gfp_t gfp)
321{
322 struct z3fold_header *zhdr = page_address(page);
323 struct z3fold_buddy_slots *slots;
324
325 clear_bit(PAGE_HEADLESS, &page->private);
326 clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
327 clear_bit(NEEDS_COMPACTING, &page->private);
328 clear_bit(PAGE_STALE, &page->private);
329 clear_bit(PAGE_CLAIMED, &page->private);
330 clear_bit(PAGE_MIGRATED, &page->private);
331 if (headless)
332 return zhdr;
333
334 slots = alloc_slots(pool, gfp);
335 if (!slots)
336 return NULL;
337
338 memset(zhdr, 0, sizeof(*zhdr));
339 spin_lock_init(&zhdr->page_lock);
340 kref_init(&zhdr->refcount);
341 zhdr->cpu = -1;
342 zhdr->slots = slots;
343 zhdr->pool = pool;
344 INIT_LIST_HEAD(&zhdr->buddy);
345 INIT_WORK(&zhdr->work, compact_page_work);
346 return zhdr;
347}
348
349/* Resets the struct page fields and frees the page */
350static void free_z3fold_page(struct page *page, bool headless)
351{
352 if (!headless) {
353 lock_page(page);
354 __ClearPageMovable(page);
355 unlock_page(page);
356 }
357 __free_page(page);
358}
359
360/* Helper function to build the index */
361static inline int __idx(struct z3fold_header *zhdr, enum buddy bud)
362{
363 return (bud + zhdr->first_num) & BUDDY_MASK;
364}
365
366/*
367 * Encodes the handle of a particular buddy within a z3fold page
368 * Pool lock should be held as this function accesses first_num
369 */
370static unsigned long __encode_handle(struct z3fold_header *zhdr,
371 struct z3fold_buddy_slots *slots,
372 enum buddy bud)
373{
374 unsigned long h = (unsigned long)zhdr;
375 int idx = 0;
376
377 /*
378 * For a headless page, its handle is its pointer with the extra
379 * PAGE_HEADLESS bit set
380 */
381 if (bud == HEADLESS)
382 return h | (1 << PAGE_HEADLESS);
383
384 /* otherwise, return pointer to encoded handle */
385 idx = __idx(zhdr, bud);
386 h += idx;
387 if (bud == LAST)
388 h |= (zhdr->last_chunks << BUDDY_SHIFT);
389
390 write_lock(&slots->lock);
391 slots->slot[idx] = h;
392 write_unlock(&slots->lock);
393 return (unsigned long)&slots->slot[idx];
394}
395
396static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud)
397{
398 return __encode_handle(zhdr, zhdr->slots, bud);
399}
400
401/* only for LAST bud, returns zero otherwise */
402static unsigned short handle_to_chunks(unsigned long handle)
403{
404 struct z3fold_buddy_slots *slots = handle_to_slots(handle);
405 unsigned long addr;
406
407 read_lock(&slots->lock);
408 addr = *(unsigned long *)handle;
409 read_unlock(&slots->lock);
410 return (addr & ~PAGE_MASK) >> BUDDY_SHIFT;
411}
412
413/*
414 * (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle
415 * but that doesn't matter. because the masking will result in the
416 * correct buddy number.
417 */
418static enum buddy handle_to_buddy(unsigned long handle)
419{
420 struct z3fold_header *zhdr;
421 struct z3fold_buddy_slots *slots = handle_to_slots(handle);
422 unsigned long addr;
423
424 read_lock(&slots->lock);
425 WARN_ON(handle & (1 << PAGE_HEADLESS));
426 addr = *(unsigned long *)handle;
427 read_unlock(&slots->lock);
428 zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
429 return (addr - zhdr->first_num) & BUDDY_MASK;
430}
431
432static inline struct z3fold_pool *zhdr_to_pool(struct z3fold_header *zhdr)
433{
434 return zhdr->pool;
435}
436
437static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked)
438{
439 struct page *page = virt_to_page(zhdr);
440 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
441
442 WARN_ON(!list_empty(&zhdr->buddy));
443 set_bit(PAGE_STALE, &page->private);
444 clear_bit(NEEDS_COMPACTING, &page->private);
445 spin_lock(&pool->lock);
446 spin_unlock(&pool->lock);
447
448 if (locked)
449 z3fold_page_unlock(zhdr);
450
451 spin_lock(&pool->stale_lock);
452 list_add(&zhdr->buddy, &pool->stale);
453 queue_work(pool->release_wq, &pool->work);
454 spin_unlock(&pool->stale_lock);
455
456 atomic64_dec(&pool->pages_nr);
457}
458
459static void release_z3fold_page_locked(struct kref *ref)
460{
461 struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
462 refcount);
463 WARN_ON(z3fold_page_trylock(zhdr));
464 __release_z3fold_page(zhdr, true);
465}
466
467static void release_z3fold_page_locked_list(struct kref *ref)
468{
469 struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
470 refcount);
471 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
472
473 spin_lock(&pool->lock);
474 list_del_init(&zhdr->buddy);
475 spin_unlock(&pool->lock);
476
477 WARN_ON(z3fold_page_trylock(zhdr));
478 __release_z3fold_page(zhdr, true);
479}
480
481static inline int put_z3fold_locked(struct z3fold_header *zhdr)
482{
483 return kref_put(&zhdr->refcount, release_z3fold_page_locked);
484}
485
486static inline int put_z3fold_locked_list(struct z3fold_header *zhdr)
487{
488 return kref_put(&zhdr->refcount, release_z3fold_page_locked_list);
489}
490
491static void free_pages_work(struct work_struct *w)
492{
493 struct z3fold_pool *pool = container_of(w, struct z3fold_pool, work);
494
495 spin_lock(&pool->stale_lock);
496 while (!list_empty(&pool->stale)) {
497 struct z3fold_header *zhdr = list_first_entry(&pool->stale,
498 struct z3fold_header, buddy);
499 struct page *page = virt_to_page(zhdr);
500
501 list_del(&zhdr->buddy);
502 if (WARN_ON(!test_bit(PAGE_STALE, &page->private)))
503 continue;
504 spin_unlock(&pool->stale_lock);
505 cancel_work_sync(&zhdr->work);
506 free_z3fold_page(page, false);
507 cond_resched();
508 spin_lock(&pool->stale_lock);
509 }
510 spin_unlock(&pool->stale_lock);
511}
512
513/*
514 * Returns the number of free chunks in a z3fold page.
515 * NB: can't be used with HEADLESS pages.
516 */
517static int num_free_chunks(struct z3fold_header *zhdr)
518{
519 int nfree;
520 /*
521 * If there is a middle object, pick up the bigger free space
522 * either before or after it. Otherwise just subtract the number
523 * of chunks occupied by the first and the last objects.
524 */
525 if (zhdr->middle_chunks != 0) {
526 int nfree_before = zhdr->first_chunks ?
527 0 : zhdr->start_middle - ZHDR_CHUNKS;
528 int nfree_after = zhdr->last_chunks ?
529 0 : TOTAL_CHUNKS -
530 (zhdr->start_middle + zhdr->middle_chunks);
531 nfree = max(nfree_before, nfree_after);
532 } else
533 nfree = NCHUNKS - zhdr->first_chunks - zhdr->last_chunks;
534 return nfree;
535}
536
537/* Add to the appropriate unbuddied list */
538static inline void add_to_unbuddied(struct z3fold_pool *pool,
539 struct z3fold_header *zhdr)
540{
541 if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 ||
542 zhdr->middle_chunks == 0) {
543 struct list_head *unbuddied;
544 int freechunks = num_free_chunks(zhdr);
545
546 migrate_disable();
547 unbuddied = this_cpu_ptr(pool->unbuddied);
548 spin_lock(&pool->lock);
549 list_add(&zhdr->buddy, &unbuddied[freechunks]);
550 spin_unlock(&pool->lock);
551 zhdr->cpu = smp_processor_id();
552 migrate_enable();
553 }
554}
555
556static inline enum buddy get_free_buddy(struct z3fold_header *zhdr, int chunks)
557{
558 enum buddy bud = HEADLESS;
559
560 if (zhdr->middle_chunks) {
561 if (!zhdr->first_chunks &&
562 chunks <= zhdr->start_middle - ZHDR_CHUNKS)
563 bud = FIRST;
564 else if (!zhdr->last_chunks)
565 bud = LAST;
566 } else {
567 if (!zhdr->first_chunks)
568 bud = FIRST;
569 else if (!zhdr->last_chunks)
570 bud = LAST;
571 else
572 bud = MIDDLE;
573 }
574
575 return bud;
576}
577
578static inline void *mchunk_memmove(struct z3fold_header *zhdr,
579 unsigned short dst_chunk)
580{
581 void *beg = zhdr;
582 return memmove(beg + (dst_chunk << CHUNK_SHIFT),
583 beg + (zhdr->start_middle << CHUNK_SHIFT),
584 zhdr->middle_chunks << CHUNK_SHIFT);
585}
586
587static inline bool buddy_single(struct z3fold_header *zhdr)
588{
589 return !((zhdr->first_chunks && zhdr->middle_chunks) ||
590 (zhdr->first_chunks && zhdr->last_chunks) ||
591 (zhdr->middle_chunks && zhdr->last_chunks));
592}
593
594static struct z3fold_header *compact_single_buddy(struct z3fold_header *zhdr)
595{
596 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
597 void *p = zhdr;
598 unsigned long old_handle = 0;
599 size_t sz = 0;
600 struct z3fold_header *new_zhdr = NULL;
601 int first_idx = __idx(zhdr, FIRST);
602 int middle_idx = __idx(zhdr, MIDDLE);
603 int last_idx = __idx(zhdr, LAST);
604 unsigned short *moved_chunks = NULL;
605
606 /*
607 * No need to protect slots here -- all the slots are "local" and
608 * the page lock is already taken
609 */
610 if (zhdr->first_chunks && zhdr->slots->slot[first_idx]) {
611 p += ZHDR_SIZE_ALIGNED;
612 sz = zhdr->first_chunks << CHUNK_SHIFT;
613 old_handle = (unsigned long)&zhdr->slots->slot[first_idx];
614 moved_chunks = &zhdr->first_chunks;
615 } else if (zhdr->middle_chunks && zhdr->slots->slot[middle_idx]) {
616 p += zhdr->start_middle << CHUNK_SHIFT;
617 sz = zhdr->middle_chunks << CHUNK_SHIFT;
618 old_handle = (unsigned long)&zhdr->slots->slot[middle_idx];
619 moved_chunks = &zhdr->middle_chunks;
620 } else if (zhdr->last_chunks && zhdr->slots->slot[last_idx]) {
621 p += PAGE_SIZE - (zhdr->last_chunks << CHUNK_SHIFT);
622 sz = zhdr->last_chunks << CHUNK_SHIFT;
623 old_handle = (unsigned long)&zhdr->slots->slot[last_idx];
624 moved_chunks = &zhdr->last_chunks;
625 }
626
627 if (sz > 0) {
628 enum buddy new_bud = HEADLESS;
629 short chunks = size_to_chunks(sz);
630 void *q;
631
632 new_zhdr = __z3fold_alloc(pool, sz, false);
633 if (!new_zhdr)
634 return NULL;
635
636 if (WARN_ON(new_zhdr == zhdr))
637 goto out_fail;
638
639 new_bud = get_free_buddy(new_zhdr, chunks);
640 q = new_zhdr;
641 switch (new_bud) {
642 case FIRST:
643 new_zhdr->first_chunks = chunks;
644 q += ZHDR_SIZE_ALIGNED;
645 break;
646 case MIDDLE:
647 new_zhdr->middle_chunks = chunks;
648 new_zhdr->start_middle =
649 new_zhdr->first_chunks + ZHDR_CHUNKS;
650 q += new_zhdr->start_middle << CHUNK_SHIFT;
651 break;
652 case LAST:
653 new_zhdr->last_chunks = chunks;
654 q += PAGE_SIZE - (new_zhdr->last_chunks << CHUNK_SHIFT);
655 break;
656 default:
657 goto out_fail;
658 }
659 new_zhdr->foreign_handles++;
660 memcpy(q, p, sz);
661 write_lock(&zhdr->slots->lock);
662 *(unsigned long *)old_handle = (unsigned long)new_zhdr +
663 __idx(new_zhdr, new_bud);
664 if (new_bud == LAST)
665 *(unsigned long *)old_handle |=
666 (new_zhdr->last_chunks << BUDDY_SHIFT);
667 write_unlock(&zhdr->slots->lock);
668 add_to_unbuddied(pool, new_zhdr);
669 z3fold_page_unlock(new_zhdr);
670
671 *moved_chunks = 0;
672 }
673
674 return new_zhdr;
675
676out_fail:
677 if (new_zhdr && !put_z3fold_locked(new_zhdr)) {
678 add_to_unbuddied(pool, new_zhdr);
679 z3fold_page_unlock(new_zhdr);
680 }
681 return NULL;
682
683}
684
685#define BIG_CHUNK_GAP 3
686/* Has to be called with lock held */
687static int z3fold_compact_page(struct z3fold_header *zhdr)
688{
689 struct page *page = virt_to_page(zhdr);
690
691 if (test_bit(MIDDLE_CHUNK_MAPPED, &page->private))
692 return 0; /* can't move middle chunk, it's used */
693
694 if (unlikely(PageIsolated(page)))
695 return 0;
696
697 if (zhdr->middle_chunks == 0)
698 return 0; /* nothing to compact */
699
700 if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
701 /* move to the beginning */
702 mchunk_memmove(zhdr, ZHDR_CHUNKS);
703 zhdr->first_chunks = zhdr->middle_chunks;
704 zhdr->middle_chunks = 0;
705 zhdr->start_middle = 0;
706 zhdr->first_num++;
707 return 1;
708 }
709
710 /*
711 * moving data is expensive, so let's only do that if
712 * there's substantial gain (at least BIG_CHUNK_GAP chunks)
713 */
714 if (zhdr->first_chunks != 0 && zhdr->last_chunks == 0 &&
715 zhdr->start_middle - (zhdr->first_chunks + ZHDR_CHUNKS) >=
716 BIG_CHUNK_GAP) {
717 mchunk_memmove(zhdr, zhdr->first_chunks + ZHDR_CHUNKS);
718 zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
719 return 1;
720 } else if (zhdr->last_chunks != 0 && zhdr->first_chunks == 0 &&
721 TOTAL_CHUNKS - (zhdr->last_chunks + zhdr->start_middle
722 + zhdr->middle_chunks) >=
723 BIG_CHUNK_GAP) {
724 unsigned short new_start = TOTAL_CHUNKS - zhdr->last_chunks -
725 zhdr->middle_chunks;
726 mchunk_memmove(zhdr, new_start);
727 zhdr->start_middle = new_start;
728 return 1;
729 }
730
731 return 0;
732}
733
734static void do_compact_page(struct z3fold_header *zhdr, bool locked)
735{
736 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
737 struct page *page;
738
739 page = virt_to_page(zhdr);
740 if (locked)
741 WARN_ON(z3fold_page_trylock(zhdr));
742 else
743 z3fold_page_lock(zhdr);
744 if (WARN_ON(!test_and_clear_bit(NEEDS_COMPACTING, &page->private))) {
745 z3fold_page_unlock(zhdr);
746 return;
747 }
748 spin_lock(&pool->lock);
749 list_del_init(&zhdr->buddy);
750 spin_unlock(&pool->lock);
751
752 if (put_z3fold_locked(zhdr))
753 return;
754
755 if (test_bit(PAGE_STALE, &page->private) ||
756 test_and_set_bit(PAGE_CLAIMED, &page->private)) {
757 z3fold_page_unlock(zhdr);
758 return;
759 }
760
761 if (!zhdr->foreign_handles && buddy_single(zhdr) &&
762 zhdr->mapped_count == 0 && compact_single_buddy(zhdr)) {
763 if (!put_z3fold_locked(zhdr)) {
764 clear_bit(PAGE_CLAIMED, &page->private);
765 z3fold_page_unlock(zhdr);
766 }
767 return;
768 }
769
770 z3fold_compact_page(zhdr);
771 add_to_unbuddied(pool, zhdr);
772 clear_bit(PAGE_CLAIMED, &page->private);
773 z3fold_page_unlock(zhdr);
774}
775
776static void compact_page_work(struct work_struct *w)
777{
778 struct z3fold_header *zhdr = container_of(w, struct z3fold_header,
779 work);
780
781 do_compact_page(zhdr, false);
782}
783
784/* returns _locked_ z3fold page header or NULL */
785static inline struct z3fold_header *__z3fold_alloc(struct z3fold_pool *pool,
786 size_t size, bool can_sleep)
787{
788 struct z3fold_header *zhdr = NULL;
789 struct page *page;
790 struct list_head *unbuddied;
791 int chunks = size_to_chunks(size), i;
792
793lookup:
794 migrate_disable();
795 /* First, try to find an unbuddied z3fold page. */
796 unbuddied = this_cpu_ptr(pool->unbuddied);
797 for_each_unbuddied_list(i, chunks) {
798 struct list_head *l = &unbuddied[i];
799
800 zhdr = list_first_entry_or_null(READ_ONCE(l),
801 struct z3fold_header, buddy);
802
803 if (!zhdr)
804 continue;
805
806 /* Re-check under lock. */
807 spin_lock(&pool->lock);
808 if (unlikely(zhdr != list_first_entry(READ_ONCE(l),
809 struct z3fold_header, buddy)) ||
810 !z3fold_page_trylock(zhdr)) {
811 spin_unlock(&pool->lock);
812 zhdr = NULL;
813 migrate_enable();
814 if (can_sleep)
815 cond_resched();
816 goto lookup;
817 }
818 list_del_init(&zhdr->buddy);
819 zhdr->cpu = -1;
820 spin_unlock(&pool->lock);
821
822 page = virt_to_page(zhdr);
823 if (test_bit(NEEDS_COMPACTING, &page->private) ||
824 test_bit(PAGE_CLAIMED, &page->private)) {
825 z3fold_page_unlock(zhdr);
826 zhdr = NULL;
827 migrate_enable();
828 if (can_sleep)
829 cond_resched();
830 goto lookup;
831 }
832
833 /*
834 * this page could not be removed from its unbuddied
835 * list while pool lock was held, and then we've taken
836 * page lock so kref_put could not be called before
837 * we got here, so it's safe to just call kref_get()
838 */
839 kref_get(&zhdr->refcount);
840 break;
841 }
842 migrate_enable();
843
844 if (!zhdr) {
845 int cpu;
846
847 /* look for _exact_ match on other cpus' lists */
848 for_each_online_cpu(cpu) {
849 struct list_head *l;
850
851 unbuddied = per_cpu_ptr(pool->unbuddied, cpu);
852 spin_lock(&pool->lock);
853 l = &unbuddied[chunks];
854
855 zhdr = list_first_entry_or_null(READ_ONCE(l),
856 struct z3fold_header, buddy);
857
858 if (!zhdr || !z3fold_page_trylock(zhdr)) {
859 spin_unlock(&pool->lock);
860 zhdr = NULL;
861 continue;
862 }
863 list_del_init(&zhdr->buddy);
864 zhdr->cpu = -1;
865 spin_unlock(&pool->lock);
866
867 page = virt_to_page(zhdr);
868 if (test_bit(NEEDS_COMPACTING, &page->private) ||
869 test_bit(PAGE_CLAIMED, &page->private)) {
870 z3fold_page_unlock(zhdr);
871 zhdr = NULL;
872 if (can_sleep)
873 cond_resched();
874 continue;
875 }
876 kref_get(&zhdr->refcount);
877 break;
878 }
879 }
880
881 if (zhdr && !zhdr->slots) {
882 zhdr->slots = alloc_slots(pool, GFP_ATOMIC);
883 if (!zhdr->slots)
884 goto out_fail;
885 }
886 return zhdr;
887
888out_fail:
889 if (!put_z3fold_locked(zhdr)) {
890 add_to_unbuddied(pool, zhdr);
891 z3fold_page_unlock(zhdr);
892 }
893 return NULL;
894}
895
896/*
897 * API Functions
898 */
899
900/**
901 * z3fold_create_pool() - create a new z3fold pool
902 * @name: pool name
903 * @gfp: gfp flags when allocating the z3fold pool structure
904 *
905 * Return: pointer to the new z3fold pool or NULL if the metadata allocation
906 * failed.
907 */
908static struct z3fold_pool *z3fold_create_pool(const char *name, gfp_t gfp)
909{
910 struct z3fold_pool *pool = NULL;
911 int i, cpu;
912
913 pool = kzalloc(sizeof(struct z3fold_pool), gfp);
914 if (!pool)
915 goto out;
916 pool->c_handle = kmem_cache_create("z3fold_handle",
917 sizeof(struct z3fold_buddy_slots),
918 SLOTS_ALIGN, 0, NULL);
919 if (!pool->c_handle)
920 goto out_c;
921 spin_lock_init(&pool->lock);
922 spin_lock_init(&pool->stale_lock);
923 pool->unbuddied = __alloc_percpu(sizeof(struct list_head) * NCHUNKS,
924 __alignof__(struct list_head));
925 if (!pool->unbuddied)
926 goto out_pool;
927 for_each_possible_cpu(cpu) {
928 struct list_head *unbuddied =
929 per_cpu_ptr(pool->unbuddied, cpu);
930 for_each_unbuddied_list(i, 0)
931 INIT_LIST_HEAD(&unbuddied[i]);
932 }
933 INIT_LIST_HEAD(&pool->stale);
934 atomic64_set(&pool->pages_nr, 0);
935 pool->name = name;
936 pool->compact_wq = create_singlethread_workqueue(pool->name);
937 if (!pool->compact_wq)
938 goto out_unbuddied;
939 pool->release_wq = create_singlethread_workqueue(pool->name);
940 if (!pool->release_wq)
941 goto out_wq;
942 INIT_WORK(&pool->work, free_pages_work);
943 return pool;
944
945out_wq:
946 destroy_workqueue(pool->compact_wq);
947out_unbuddied:
948 free_percpu(pool->unbuddied);
949out_pool:
950 kmem_cache_destroy(pool->c_handle);
951out_c:
952 kfree(pool);
953out:
954 return NULL;
955}
956
957/**
958 * z3fold_destroy_pool() - destroys an existing z3fold pool
959 * @pool: the z3fold pool to be destroyed
960 *
961 * The pool should be emptied before this function is called.
962 */
963static void z3fold_destroy_pool(struct z3fold_pool *pool)
964{
965 kmem_cache_destroy(pool->c_handle);
966
967 /*
968 * We need to destroy pool->compact_wq before pool->release_wq,
969 * as any pending work on pool->compact_wq will call
970 * queue_work(pool->release_wq, &pool->work).
971 *
972 * There are still outstanding pages until both workqueues are drained,
973 * so we cannot unregister migration until then.
974 */
975
976 destroy_workqueue(pool->compact_wq);
977 destroy_workqueue(pool->release_wq);
978 free_percpu(pool->unbuddied);
979 kfree(pool);
980}
981
982static const struct movable_operations z3fold_mops;
983
984/**
985 * z3fold_alloc() - allocates a region of a given size
986 * @pool: z3fold pool from which to allocate
987 * @size: size in bytes of the desired allocation
988 * @gfp: gfp flags used if the pool needs to grow
989 * @handle: handle of the new allocation
990 *
991 * This function will attempt to find a free region in the pool large enough to
992 * satisfy the allocation request. A search of the unbuddied lists is
993 * performed first. If no suitable free region is found, then a new page is
994 * allocated and added to the pool to satisfy the request.
995 *
996 * Return: 0 if success and handle is set, otherwise -EINVAL if the size or
997 * gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
998 * a new page.
999 */
1000static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
1001 unsigned long *handle)
1002{
1003 int chunks = size_to_chunks(size);
1004 struct z3fold_header *zhdr = NULL;
1005 struct page *page = NULL;
1006 enum buddy bud;
1007 bool can_sleep = gfpflags_allow_blocking(gfp);
1008
1009 if (!size || (gfp & __GFP_HIGHMEM))
1010 return -EINVAL;
1011
1012 if (size > PAGE_SIZE)
1013 return -ENOSPC;
1014
1015 if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
1016 bud = HEADLESS;
1017 else {
1018retry:
1019 zhdr = __z3fold_alloc(pool, size, can_sleep);
1020 if (zhdr) {
1021 bud = get_free_buddy(zhdr, chunks);
1022 if (bud == HEADLESS) {
1023 if (!put_z3fold_locked(zhdr))
1024 z3fold_page_unlock(zhdr);
1025 pr_err("No free chunks in unbuddied\n");
1026 WARN_ON(1);
1027 goto retry;
1028 }
1029 page = virt_to_page(zhdr);
1030 goto found;
1031 }
1032 bud = FIRST;
1033 }
1034
1035 page = alloc_page(gfp);
1036 if (!page)
1037 return -ENOMEM;
1038
1039 zhdr = init_z3fold_page(page, bud == HEADLESS, pool, gfp);
1040 if (!zhdr) {
1041 __free_page(page);
1042 return -ENOMEM;
1043 }
1044 atomic64_inc(&pool->pages_nr);
1045
1046 if (bud == HEADLESS) {
1047 set_bit(PAGE_HEADLESS, &page->private);
1048 goto headless;
1049 }
1050 if (can_sleep) {
1051 lock_page(page);
1052 __SetPageMovable(page, &z3fold_mops);
1053 unlock_page(page);
1054 } else {
1055 WARN_ON(!trylock_page(page));
1056 __SetPageMovable(page, &z3fold_mops);
1057 unlock_page(page);
1058 }
1059 z3fold_page_lock(zhdr);
1060
1061found:
1062 if (bud == FIRST)
1063 zhdr->first_chunks = chunks;
1064 else if (bud == LAST)
1065 zhdr->last_chunks = chunks;
1066 else {
1067 zhdr->middle_chunks = chunks;
1068 zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
1069 }
1070 add_to_unbuddied(pool, zhdr);
1071
1072headless:
1073 spin_lock(&pool->lock);
1074 *handle = encode_handle(zhdr, bud);
1075 spin_unlock(&pool->lock);
1076 if (bud != HEADLESS)
1077 z3fold_page_unlock(zhdr);
1078
1079 return 0;
1080}
1081
1082/**
1083 * z3fold_free() - frees the allocation associated with the given handle
1084 * @pool: pool in which the allocation resided
1085 * @handle: handle associated with the allocation returned by z3fold_alloc()
1086 *
1087 * In the case that the z3fold page in which the allocation resides is under
1088 * reclaim, as indicated by the PAGE_CLAIMED flag being set, this function
1089 * only sets the first|middle|last_chunks to 0. The page is actually freed
1090 * once all buddies are evicted (see z3fold_reclaim_page() below).
1091 */
1092static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
1093{
1094 struct z3fold_header *zhdr;
1095 struct page *page;
1096 enum buddy bud;
1097 bool page_claimed;
1098
1099 zhdr = get_z3fold_header(handle);
1100 page = virt_to_page(zhdr);
1101 page_claimed = test_and_set_bit(PAGE_CLAIMED, &page->private);
1102
1103 if (test_bit(PAGE_HEADLESS, &page->private)) {
1104 /* if a headless page is under reclaim, just leave.
1105 * NB: we use test_and_set_bit for a reason: if the bit
1106 * has not been set before, we release this page
1107 * immediately so we don't care about its value any more.
1108 */
1109 if (!page_claimed) {
1110 put_z3fold_header(zhdr);
1111 free_z3fold_page(page, true);
1112 atomic64_dec(&pool->pages_nr);
1113 }
1114 return;
1115 }
1116
1117 /* Non-headless case */
1118 bud = handle_to_buddy(handle);
1119
1120 switch (bud) {
1121 case FIRST:
1122 zhdr->first_chunks = 0;
1123 break;
1124 case MIDDLE:
1125 zhdr->middle_chunks = 0;
1126 break;
1127 case LAST:
1128 zhdr->last_chunks = 0;
1129 break;
1130 default:
1131 pr_err("%s: unknown bud %d\n", __func__, bud);
1132 WARN_ON(1);
1133 put_z3fold_header(zhdr);
1134 return;
1135 }
1136
1137 if (!page_claimed)
1138 free_handle(handle, zhdr);
1139 if (put_z3fold_locked_list(zhdr))
1140 return;
1141 if (page_claimed) {
1142 /* the page has not been claimed by us */
1143 put_z3fold_header(zhdr);
1144 return;
1145 }
1146 if (test_and_set_bit(NEEDS_COMPACTING, &page->private)) {
1147 clear_bit(PAGE_CLAIMED, &page->private);
1148 put_z3fold_header(zhdr);
1149 return;
1150 }
1151 if (zhdr->cpu < 0 || !cpu_online(zhdr->cpu)) {
1152 zhdr->cpu = -1;
1153 kref_get(&zhdr->refcount);
1154 clear_bit(PAGE_CLAIMED, &page->private);
1155 do_compact_page(zhdr, true);
1156 return;
1157 }
1158 kref_get(&zhdr->refcount);
1159 clear_bit(PAGE_CLAIMED, &page->private);
1160 queue_work_on(zhdr->cpu, pool->compact_wq, &zhdr->work);
1161 put_z3fold_header(zhdr);
1162}
1163
1164/**
1165 * z3fold_map() - maps the allocation associated with the given handle
1166 * @pool: pool in which the allocation resides
1167 * @handle: handle associated with the allocation to be mapped
1168 *
1169 * Extracts the buddy number from handle and constructs the pointer to the
1170 * correct starting chunk within the page.
1171 *
1172 * Returns: a pointer to the mapped allocation
1173 */
1174static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle)
1175{
1176 struct z3fold_header *zhdr;
1177 struct page *page;
1178 void *addr;
1179 enum buddy buddy;
1180
1181 zhdr = get_z3fold_header(handle);
1182 addr = zhdr;
1183 page = virt_to_page(zhdr);
1184
1185 if (test_bit(PAGE_HEADLESS, &page->private))
1186 goto out;
1187
1188 buddy = handle_to_buddy(handle);
1189 switch (buddy) {
1190 case FIRST:
1191 addr += ZHDR_SIZE_ALIGNED;
1192 break;
1193 case MIDDLE:
1194 addr += zhdr->start_middle << CHUNK_SHIFT;
1195 set_bit(MIDDLE_CHUNK_MAPPED, &page->private);
1196 break;
1197 case LAST:
1198 addr += PAGE_SIZE - (handle_to_chunks(handle) << CHUNK_SHIFT);
1199 break;
1200 default:
1201 pr_err("unknown buddy id %d\n", buddy);
1202 WARN_ON(1);
1203 addr = NULL;
1204 break;
1205 }
1206
1207 if (addr)
1208 zhdr->mapped_count++;
1209out:
1210 put_z3fold_header(zhdr);
1211 return addr;
1212}
1213
1214/**
1215 * z3fold_unmap() - unmaps the allocation associated with the given handle
1216 * @pool: pool in which the allocation resides
1217 * @handle: handle associated with the allocation to be unmapped
1218 */
1219static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle)
1220{
1221 struct z3fold_header *zhdr;
1222 struct page *page;
1223 enum buddy buddy;
1224
1225 zhdr = get_z3fold_header(handle);
1226 page = virt_to_page(zhdr);
1227
1228 if (test_bit(PAGE_HEADLESS, &page->private))
1229 return;
1230
1231 buddy = handle_to_buddy(handle);
1232 if (buddy == MIDDLE)
1233 clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
1234 zhdr->mapped_count--;
1235 put_z3fold_header(zhdr);
1236}
1237
1238/**
1239 * z3fold_get_pool_size() - gets the z3fold pool size in pages
1240 * @pool: pool whose size is being queried
1241 *
1242 * Returns: size in pages of the given pool.
1243 */
1244static u64 z3fold_get_pool_size(struct z3fold_pool *pool)
1245{
1246 return atomic64_read(&pool->pages_nr);
1247}
1248
1249static bool z3fold_page_isolate(struct page *page, isolate_mode_t mode)
1250{
1251 struct z3fold_header *zhdr;
1252 struct z3fold_pool *pool;
1253
1254 VM_BUG_ON_PAGE(PageIsolated(page), page);
1255
1256 if (test_bit(PAGE_HEADLESS, &page->private))
1257 return false;
1258
1259 zhdr = page_address(page);
1260 z3fold_page_lock(zhdr);
1261 if (test_bit(NEEDS_COMPACTING, &page->private) ||
1262 test_bit(PAGE_STALE, &page->private))
1263 goto out;
1264
1265 if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0)
1266 goto out;
1267
1268 if (test_and_set_bit(PAGE_CLAIMED, &page->private))
1269 goto out;
1270 pool = zhdr_to_pool(zhdr);
1271 spin_lock(&pool->lock);
1272 if (!list_empty(&zhdr->buddy))
1273 list_del_init(&zhdr->buddy);
1274 spin_unlock(&pool->lock);
1275
1276 kref_get(&zhdr->refcount);
1277 z3fold_page_unlock(zhdr);
1278 return true;
1279
1280out:
1281 z3fold_page_unlock(zhdr);
1282 return false;
1283}
1284
1285static int z3fold_page_migrate(struct page *newpage, struct page *page,
1286 enum migrate_mode mode)
1287{
1288 struct z3fold_header *zhdr, *new_zhdr;
1289 struct z3fold_pool *pool;
1290
1291 VM_BUG_ON_PAGE(!PageIsolated(page), page);
1292 VM_BUG_ON_PAGE(!test_bit(PAGE_CLAIMED, &page->private), page);
1293 VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
1294
1295 zhdr = page_address(page);
1296 pool = zhdr_to_pool(zhdr);
1297
1298 if (!z3fold_page_trylock(zhdr))
1299 return -EAGAIN;
1300 if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0) {
1301 clear_bit(PAGE_CLAIMED, &page->private);
1302 z3fold_page_unlock(zhdr);
1303 return -EBUSY;
1304 }
1305 if (work_pending(&zhdr->work)) {
1306 z3fold_page_unlock(zhdr);
1307 return -EAGAIN;
1308 }
1309 new_zhdr = page_address(newpage);
1310 memcpy(new_zhdr, zhdr, PAGE_SIZE);
1311 newpage->private = page->private;
1312 set_bit(PAGE_MIGRATED, &page->private);
1313 z3fold_page_unlock(zhdr);
1314 spin_lock_init(&new_zhdr->page_lock);
1315 INIT_WORK(&new_zhdr->work, compact_page_work);
1316 /*
1317 * z3fold_page_isolate() ensures that new_zhdr->buddy is empty,
1318 * so we only have to reinitialize it.
1319 */
1320 INIT_LIST_HEAD(&new_zhdr->buddy);
1321 __ClearPageMovable(page);
1322
1323 get_page(newpage);
1324 z3fold_page_lock(new_zhdr);
1325 if (new_zhdr->first_chunks)
1326 encode_handle(new_zhdr, FIRST);
1327 if (new_zhdr->last_chunks)
1328 encode_handle(new_zhdr, LAST);
1329 if (new_zhdr->middle_chunks)
1330 encode_handle(new_zhdr, MIDDLE);
1331 set_bit(NEEDS_COMPACTING, &newpage->private);
1332 new_zhdr->cpu = smp_processor_id();
1333 __SetPageMovable(newpage, &z3fold_mops);
1334 z3fold_page_unlock(new_zhdr);
1335
1336 queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work);
1337
1338 /* PAGE_CLAIMED and PAGE_MIGRATED are cleared now. */
1339 page->private = 0;
1340 put_page(page);
1341 return 0;
1342}
1343
1344static void z3fold_page_putback(struct page *page)
1345{
1346 struct z3fold_header *zhdr;
1347 struct z3fold_pool *pool;
1348
1349 zhdr = page_address(page);
1350 pool = zhdr_to_pool(zhdr);
1351
1352 z3fold_page_lock(zhdr);
1353 if (!list_empty(&zhdr->buddy))
1354 list_del_init(&zhdr->buddy);
1355 INIT_LIST_HEAD(&page->lru);
1356 if (put_z3fold_locked(zhdr))
1357 return;
1358 if (list_empty(&zhdr->buddy))
1359 add_to_unbuddied(pool, zhdr);
1360 clear_bit(PAGE_CLAIMED, &page->private);
1361 z3fold_page_unlock(zhdr);
1362}
1363
1364static const struct movable_operations z3fold_mops = {
1365 .isolate_page = z3fold_page_isolate,
1366 .migrate_page = z3fold_page_migrate,
1367 .putback_page = z3fold_page_putback,
1368};
1369
1370/*****************
1371 * zpool
1372 ****************/
1373
1374static void *z3fold_zpool_create(const char *name, gfp_t gfp)
1375{
1376 return z3fold_create_pool(name, gfp);
1377}
1378
1379static void z3fold_zpool_destroy(void *pool)
1380{
1381 z3fold_destroy_pool(pool);
1382}
1383
1384static int z3fold_zpool_malloc(void *pool, size_t size, gfp_t gfp,
1385 unsigned long *handle)
1386{
1387 return z3fold_alloc(pool, size, gfp, handle);
1388}
1389static void z3fold_zpool_free(void *pool, unsigned long handle)
1390{
1391 z3fold_free(pool, handle);
1392}
1393
1394static void *z3fold_zpool_map(void *pool, unsigned long handle,
1395 enum zpool_mapmode mm)
1396{
1397 return z3fold_map(pool, handle);
1398}
1399static void z3fold_zpool_unmap(void *pool, unsigned long handle)
1400{
1401 z3fold_unmap(pool, handle);
1402}
1403
1404static u64 z3fold_zpool_total_size(void *pool)
1405{
1406 return z3fold_get_pool_size(pool) * PAGE_SIZE;
1407}
1408
1409static struct zpool_driver z3fold_zpool_driver = {
1410 .type = "z3fold",
1411 .sleep_mapped = true,
1412 .owner = THIS_MODULE,
1413 .create = z3fold_zpool_create,
1414 .destroy = z3fold_zpool_destroy,
1415 .malloc = z3fold_zpool_malloc,
1416 .free = z3fold_zpool_free,
1417 .map = z3fold_zpool_map,
1418 .unmap = z3fold_zpool_unmap,
1419 .total_size = z3fold_zpool_total_size,
1420};
1421
1422MODULE_ALIAS("zpool-z3fold");
1423
1424static int __init init_z3fold(void)
1425{
1426 /*
1427 * Make sure the z3fold header is not larger than the page size and
1428 * there has remaining spaces for its buddy.
1429 */
1430 BUILD_BUG_ON(ZHDR_SIZE_ALIGNED > PAGE_SIZE - CHUNK_SIZE);
1431 zpool_register_driver(&z3fold_zpool_driver);
1432
1433 return 0;
1434}
1435
1436static void __exit exit_z3fold(void)
1437{
1438 zpool_unregister_driver(&z3fold_zpool_driver);
1439}
1440
1441module_init(init_z3fold);
1442module_exit(exit_z3fold);
1443
1444MODULE_LICENSE("GPL");
1445MODULE_AUTHOR("Vitaly Wool <vitalywool@gmail.com>");
1446MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages");