1/*
2 * zsmalloc memory allocator
3 *
4 * Copyright (C) 2011 Nitin Gupta
5 * Copyright (C) 2012, 2013 Minchan Kim
6 *
7 * This code is released using a dual license strategy: BSD/GPL
8 * You can choose the license that better fits your requirements.
9 *
10 * Released under the terms of 3-clause BSD License
11 * Released under the terms of GNU General Public License Version 2.0
12 */
13
14/*
15 * Following is how we use various fields and flags of underlying
16 * struct page(s) to form a zspage.
17 *
18 * Usage of struct page fields:
19 * page->private: points to zspage
20 * page->freelist(index): links together all component pages of a zspage
21 * For the huge page, this is always 0, so we use this field
22 * to store handle.
23 * page->units: first object offset in a subpage of zspage
24 *
25 * Usage of struct page flags:
26 * PG_private: identifies the first component page
27 * PG_owner_priv_1: identifies the huge component page
28 *
29 */
30
31#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
32
33#include <linux/module.h>
34#include <linux/kernel.h>
35#include <linux/sched.h>
36#include <linux/magic.h>
37#include <linux/bitops.h>
38#include <linux/errno.h>
39#include <linux/highmem.h>
40#include <linux/string.h>
41#include <linux/slab.h>
42#include <asm/tlbflush.h>
43#include <asm/pgtable.h>
44#include <linux/cpumask.h>
45#include <linux/cpu.h>
46#include <linux/vmalloc.h>
47#include <linux/preempt.h>
48#include <linux/spinlock.h>
49#include <linux/shrinker.h>
50#include <linux/types.h>
51#include <linux/debugfs.h>
52#include <linux/zsmalloc.h>
53#include <linux/zpool.h>
54#include <linux/mount.h>
55#include <linux/migrate.h>
56#include <linux/pagemap.h>
57#include <linux/fs.h>
58
59#define ZSPAGE_MAGIC 0x58
60
61/*
62 * This must be power of 2 and greater than of equal to sizeof(link_free).
63 * These two conditions ensure that any 'struct link_free' itself doesn't
64 * span more than 1 page which avoids complex case of mapping 2 pages simply
65 * to restore link_free pointer values.
66 */
67#define ZS_ALIGN 8
68
69/*
70 * A single 'zspage' is composed of up to 2^N discontiguous 0-order (single)
71 * pages. ZS_MAX_ZSPAGE_ORDER defines upper limit on N.
72 */
73#define ZS_MAX_ZSPAGE_ORDER 2
74#define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER)
75
76#define ZS_HANDLE_SIZE (sizeof(unsigned long))
77
78/*
79 * Object location (<PFN>, <obj_idx>) is encoded as
80 * as single (unsigned long) handle value.
81 *
82 * Note that object index <obj_idx> starts from 0.
83 *
84 * This is made more complicated by various memory models and PAE.
85 */
86
87#ifndef MAX_POSSIBLE_PHYSMEM_BITS
88#ifdef MAX_PHYSMEM_BITS
89#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS
90#else
91/*
92 * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just
93 * be PAGE_SHIFT
94 */
95#define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG
96#endif
97#endif
98
99#define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT)
100
101/*
102 * Memory for allocating for handle keeps object position by
103 * encoding <page, obj_idx> and the encoded value has a room
104 * in least bit(ie, look at obj_to_location).
105 * We use the bit to synchronize between object access by
106 * user and migration.
107 */
108#define HANDLE_PIN_BIT 0
109
110/*
111 * Head in allocated object should have OBJ_ALLOCATED_TAG
112 * to identify the object was allocated or not.
113 * It's okay to add the status bit in the least bit because
114 * header keeps handle which is 4byte-aligned address so we
115 * have room for two bit at least.
116 */
117#define OBJ_ALLOCATED_TAG 1
118#define OBJ_TAG_BITS 1
119#define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
120#define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
121
122#define FULLNESS_BITS 2
123#define CLASS_BITS 8
124#define ISOLATED_BITS 3
125#define MAGIC_VAL_BITS 8
126
127#define MAX(a, b) ((a) >= (b) ? (a) : (b))
128/* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
129#define ZS_MIN_ALLOC_SIZE \
130 MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
131/* each chunk includes extra space to keep handle */
132#define ZS_MAX_ALLOC_SIZE PAGE_SIZE
133
134/*
135 * On systems with 4K page size, this gives 255 size classes! There is a
136 * trader-off here:
137 * - Large number of size classes is potentially wasteful as free page are
138 * spread across these classes
139 * - Small number of size classes causes large internal fragmentation
140 * - Probably its better to use specific size classes (empirically
141 * determined). NOTE: all those class sizes must be set as multiple of
142 * ZS_ALIGN to make sure link_free itself never has to span 2 pages.
143 *
144 * ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN
145 * (reason above)
146 */
147#define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> CLASS_BITS)
148#define ZS_SIZE_CLASSES (DIV_ROUND_UP(ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE, \
149 ZS_SIZE_CLASS_DELTA) + 1)
150
151enum fullness_group {
152 ZS_EMPTY,
153 ZS_ALMOST_EMPTY,
154 ZS_ALMOST_FULL,
155 ZS_FULL,
156 NR_ZS_FULLNESS,
157};
158
159enum zs_stat_type {
160 CLASS_EMPTY,
161 CLASS_ALMOST_EMPTY,
162 CLASS_ALMOST_FULL,
163 CLASS_FULL,
164 OBJ_ALLOCATED,
165 OBJ_USED,
166 NR_ZS_STAT_TYPE,
167};
168
169struct zs_size_stat {
170 unsigned long objs[NR_ZS_STAT_TYPE];
171};
172
173#ifdef CONFIG_ZSMALLOC_STAT
174static struct dentry *zs_stat_root;
175#endif
176
177#ifdef CONFIG_COMPACTION
178static struct vfsmount *zsmalloc_mnt;
179#endif
180
181/*
182 * We assign a page to ZS_ALMOST_EMPTY fullness group when:
183 * n <= N / f, where
184 * n = number of allocated objects
185 * N = total number of objects zspage can store
186 * f = fullness_threshold_frac
187 *
188 * Similarly, we assign zspage to:
189 * ZS_ALMOST_FULL when n > N / f
190 * ZS_EMPTY when n == 0
191 * ZS_FULL when n == N
192 *
193 * (see: fix_fullness_group())
194 */
195static const int fullness_threshold_frac = 4;
196static size_t huge_class_size;
197
198struct size_class {
199 spinlock_t lock;
200 struct list_head fullness_list[NR_ZS_FULLNESS];
201 /*
202 * Size of objects stored in this class. Must be multiple
203 * of ZS_ALIGN.
204 */
205 int size;
206 int objs_per_zspage;
207 /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
208 int pages_per_zspage;
209
210 unsigned int index;
211 struct zs_size_stat stats;
212};
213
214/* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
215static void SetPageHugeObject(struct page *page)
216{
217 SetPageOwnerPriv1(page);
218}
219
220static void ClearPageHugeObject(struct page *page)
221{
222 ClearPageOwnerPriv1(page);
223}
224
225static int PageHugeObject(struct page *page)
226{
227 return PageOwnerPriv1(page);
228}
229
230/*
231 * Placed within free objects to form a singly linked list.
232 * For every zspage, zspage->freeobj gives head of this list.
233 *
234 * This must be power of 2 and less than or equal to ZS_ALIGN
235 */
236struct link_free {
237 union {
238 /*
239 * Free object index;
240 * It's valid for non-allocated object
241 */
242 unsigned long next;
243 /*
244 * Handle of allocated object.
245 */
246 unsigned long handle;
247 };
248};
249
250struct zs_pool {
251 const char *name;
252
253 struct size_class *size_class[ZS_SIZE_CLASSES];
254 struct kmem_cache *handle_cachep;
255 struct kmem_cache *zspage_cachep;
256
257 atomic_long_t pages_allocated;
258
259 struct zs_pool_stats stats;
260
261 /* Compact classes */
262 struct shrinker shrinker;
263
264#ifdef CONFIG_ZSMALLOC_STAT
265 struct dentry *stat_dentry;
266#endif
267#ifdef CONFIG_COMPACTION
268 struct inode *inode;
269 struct work_struct free_work;
270#endif
271};
272
273struct zspage {
274 struct {
275 unsigned int fullness:FULLNESS_BITS;
276 unsigned int class:CLASS_BITS + 1;
277 unsigned int isolated:ISOLATED_BITS;
278 unsigned int magic:MAGIC_VAL_BITS;
279 };
280 unsigned int inuse;
281 unsigned int freeobj;
282 struct page *first_page;
283 struct list_head list; /* fullness list */
284#ifdef CONFIG_COMPACTION
285 rwlock_t lock;
286#endif
287};
288
289struct mapping_area {
290#ifdef CONFIG_PGTABLE_MAPPING
291 struct vm_struct *vm; /* vm area for mapping object that span pages */
292#else
293 char *vm_buf; /* copy buffer for objects that span pages */
294#endif
295 char *vm_addr; /* address of kmap_atomic()'ed pages */
296 enum zs_mapmode vm_mm; /* mapping mode */
297};
298
299#ifdef CONFIG_COMPACTION
300static int zs_register_migration(struct zs_pool *pool);
301static void zs_unregister_migration(struct zs_pool *pool);
302static void migrate_lock_init(struct zspage *zspage);
303static void migrate_read_lock(struct zspage *zspage);
304static void migrate_read_unlock(struct zspage *zspage);
305static void kick_deferred_free(struct zs_pool *pool);
306static void init_deferred_free(struct zs_pool *pool);
307static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage);
308#else
309static int zsmalloc_mount(void) { return 0; }
310static void zsmalloc_unmount(void) {}
311static int zs_register_migration(struct zs_pool *pool) { return 0; }
312static void zs_unregister_migration(struct zs_pool *pool) {}
313static void migrate_lock_init(struct zspage *zspage) {}
314static void migrate_read_lock(struct zspage *zspage) {}
315static void migrate_read_unlock(struct zspage *zspage) {}
316static void kick_deferred_free(struct zs_pool *pool) {}
317static void init_deferred_free(struct zs_pool *pool) {}
318static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage) {}
319#endif
320
321static int create_cache(struct zs_pool *pool)
322{
323 pool->handle_cachep = kmem_cache_create("zs_handle", ZS_HANDLE_SIZE,
324 0, 0, NULL);
325 if (!pool->handle_cachep)
326 return 1;
327
328 pool->zspage_cachep = kmem_cache_create("zspage", sizeof(struct zspage),
329 0, 0, NULL);
330 if (!pool->zspage_cachep) {
331 kmem_cache_destroy(pool->handle_cachep);
332 pool->handle_cachep = NULL;
333 return 1;
334 }
335
336 return 0;
337}
338
339static void destroy_cache(struct zs_pool *pool)
340{
341 kmem_cache_destroy(pool->handle_cachep);
342 kmem_cache_destroy(pool->zspage_cachep);
343}
344
345static unsigned long cache_alloc_handle(struct zs_pool *pool, gfp_t gfp)
346{
347 return (unsigned long)kmem_cache_alloc(pool->handle_cachep,
348 gfp & ~(__GFP_HIGHMEM|__GFP_MOVABLE));
349}
350
351static void cache_free_handle(struct zs_pool *pool, unsigned long handle)
352{
353 kmem_cache_free(pool->handle_cachep, (void *)handle);
354}
355
356static struct zspage *cache_alloc_zspage(struct zs_pool *pool, gfp_t flags)
357{
358 return kmem_cache_alloc(pool->zspage_cachep,
359 flags & ~(__GFP_HIGHMEM|__GFP_MOVABLE));
360}
361
362static void cache_free_zspage(struct zs_pool *pool, struct zspage *zspage)
363{
364 kmem_cache_free(pool->zspage_cachep, zspage);
365}
366
367static void record_obj(unsigned long handle, unsigned long obj)
368{
369 /*
370 * lsb of @obj represents handle lock while other bits
371 * represent object value the handle is pointing so
372 * updating shouldn't do store tearing.
373 */
374 WRITE_ONCE(*(unsigned long *)handle, obj);
375}
376
377/* zpool driver */
378
379#ifdef CONFIG_ZPOOL
380
381static void *zs_zpool_create(const char *name, gfp_t gfp,
382 const struct zpool_ops *zpool_ops,
383 struct zpool *zpool)
384{
385 /*
386 * Ignore global gfp flags: zs_malloc() may be invoked from
387 * different contexts and its caller must provide a valid
388 * gfp mask.
389 */
390 return zs_create_pool(name);
391}
392
393static void zs_zpool_destroy(void *pool)
394{
395 zs_destroy_pool(pool);
396}
397
398static int zs_zpool_malloc(void *pool, size_t size, gfp_t gfp,
399 unsigned long *handle)
400{
401 *handle = zs_malloc(pool, size, gfp);
402 return *handle ? 0 : -1;
403}
404static void zs_zpool_free(void *pool, unsigned long handle)
405{
406 zs_free(pool, handle);
407}
408
409static void *zs_zpool_map(void *pool, unsigned long handle,
410 enum zpool_mapmode mm)
411{
412 enum zs_mapmode zs_mm;
413
414 switch (mm) {
415 case ZPOOL_MM_RO:
416 zs_mm = ZS_MM_RO;
417 break;
418 case ZPOOL_MM_WO:
419 zs_mm = ZS_MM_WO;
420 break;
421 case ZPOOL_MM_RW: /* fall through */
422 default:
423 zs_mm = ZS_MM_RW;
424 break;
425 }
426
427 return zs_map_object(pool, handle, zs_mm);
428}
429static void zs_zpool_unmap(void *pool, unsigned long handle)
430{
431 zs_unmap_object(pool, handle);
432}
433
434static u64 zs_zpool_total_size(void *pool)
435{
436 return zs_get_total_pages(pool) << PAGE_SHIFT;
437}
438
439static struct zpool_driver zs_zpool_driver = {
440 .type = "zsmalloc",
441 .owner = THIS_MODULE,
442 .create = zs_zpool_create,
443 .destroy = zs_zpool_destroy,
444 .malloc = zs_zpool_malloc,
445 .free = zs_zpool_free,
446 .map = zs_zpool_map,
447 .unmap = zs_zpool_unmap,
448 .total_size = zs_zpool_total_size,
449};
450
451MODULE_ALIAS("zpool-zsmalloc");
452#endif /* CONFIG_ZPOOL */
453
454/* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
455static DEFINE_PER_CPU(struct mapping_area, zs_map_area);
456
457static bool is_zspage_isolated(struct zspage *zspage)
458{
459 return zspage->isolated;
460}
461
462static __maybe_unused int is_first_page(struct page *page)
463{
464 return PagePrivate(page);
465}
466
467/* Protected by class->lock */
468static inline int get_zspage_inuse(struct zspage *zspage)
469{
470 return zspage->inuse;
471}
472
473static inline void set_zspage_inuse(struct zspage *zspage, int val)
474{
475 zspage->inuse = val;
476}
477
478static inline void mod_zspage_inuse(struct zspage *zspage, int val)
479{
480 zspage->inuse += val;
481}
482
483static inline struct page *get_first_page(struct zspage *zspage)
484{
485 struct page *first_page = zspage->first_page;
486
487 VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
488 return first_page;
489}
490
491static inline int get_first_obj_offset(struct page *page)
492{
493 return page->units;
494}
495
496static inline void set_first_obj_offset(struct page *page, int offset)
497{
498 page->units = offset;
499}
500
501static inline unsigned int get_freeobj(struct zspage *zspage)
502{
503 return zspage->freeobj;
504}
505
506static inline void set_freeobj(struct zspage *zspage, unsigned int obj)
507{
508 zspage->freeobj = obj;
509}
510
511static void get_zspage_mapping(struct zspage *zspage,
512 unsigned int *class_idx,
513 enum fullness_group *fullness)
514{
515 BUG_ON(zspage->magic != ZSPAGE_MAGIC);
516
517 *fullness = zspage->fullness;
518 *class_idx = zspage->class;
519}
520
521static void set_zspage_mapping(struct zspage *zspage,
522 unsigned int class_idx,
523 enum fullness_group fullness)
524{
525 zspage->class = class_idx;
526 zspage->fullness = fullness;
527}
528
529/*
530 * zsmalloc divides the pool into various size classes where each
531 * class maintains a list of zspages where each zspage is divided
532 * into equal sized chunks. Each allocation falls into one of these
533 * classes depending on its size. This function returns index of the
534 * size class which has chunk size big enough to hold the give size.
535 */
536static int get_size_class_index(int size)
537{
538 int idx = 0;
539
540 if (likely(size > ZS_MIN_ALLOC_SIZE))
541 idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE,
542 ZS_SIZE_CLASS_DELTA);
543
544 return min_t(int, ZS_SIZE_CLASSES - 1, idx);
545}
546
547/* type can be of enum type zs_stat_type or fullness_group */
548static inline void zs_stat_inc(struct size_class *class,
549 int type, unsigned long cnt)
550{
551 class->stats.objs[type] += cnt;
552}
553
554/* type can be of enum type zs_stat_type or fullness_group */
555static inline void zs_stat_dec(struct size_class *class,
556 int type, unsigned long cnt)
557{
558 class->stats.objs[type] -= cnt;
559}
560
561/* type can be of enum type zs_stat_type or fullness_group */
562static inline unsigned long zs_stat_get(struct size_class *class,
563 int type)
564{
565 return class->stats.objs[type];
566}
567
568#ifdef CONFIG_ZSMALLOC_STAT
569
570static void __init zs_stat_init(void)
571{
572 if (!debugfs_initialized()) {
573 pr_warn("debugfs not available, stat dir not created\n");
574 return;
575 }
576
577 zs_stat_root = debugfs_create_dir("zsmalloc", NULL);
578 if (!zs_stat_root)
579 pr_warn("debugfs 'zsmalloc' stat dir creation failed\n");
580}
581
582static void __exit zs_stat_exit(void)
583{
584 debugfs_remove_recursive(zs_stat_root);
585}
586
587static unsigned long zs_can_compact(struct size_class *class);
588
589static int zs_stats_size_show(struct seq_file *s, void *v)
590{
591 int i;
592 struct zs_pool *pool = s->private;
593 struct size_class *class;
594 int objs_per_zspage;
595 unsigned long class_almost_full, class_almost_empty;
596 unsigned long obj_allocated, obj_used, pages_used, freeable;
597 unsigned long total_class_almost_full = 0, total_class_almost_empty = 0;
598 unsigned long total_objs = 0, total_used_objs = 0, total_pages = 0;
599 unsigned long total_freeable = 0;
600
601 seq_printf(s, " %5s %5s %11s %12s %13s %10s %10s %16s %8s\n",
602 "class", "size", "almost_full", "almost_empty",
603 "obj_allocated", "obj_used", "pages_used",
604 "pages_per_zspage", "freeable");
605
606 for (i = 0; i < ZS_SIZE_CLASSES; i++) {
607 class = pool->size_class[i];
608
609 if (class->index != i)
610 continue;
611
612 spin_lock(&class->lock);
613 class_almost_full = zs_stat_get(class, CLASS_ALMOST_FULL);
614 class_almost_empty = zs_stat_get(class, CLASS_ALMOST_EMPTY);
615 obj_allocated = zs_stat_get(class, OBJ_ALLOCATED);
616 obj_used = zs_stat_get(class, OBJ_USED);
617 freeable = zs_can_compact(class);
618 spin_unlock(&class->lock);
619
620 objs_per_zspage = class->objs_per_zspage;
621 pages_used = obj_allocated / objs_per_zspage *
622 class->pages_per_zspage;
623
624 seq_printf(s, " %5u %5u %11lu %12lu %13lu"
625 " %10lu %10lu %16d %8lu\n",
626 i, class->size, class_almost_full, class_almost_empty,
627 obj_allocated, obj_used, pages_used,
628 class->pages_per_zspage, freeable);
629
630 total_class_almost_full += class_almost_full;
631 total_class_almost_empty += class_almost_empty;
632 total_objs += obj_allocated;
633 total_used_objs += obj_used;
634 total_pages += pages_used;
635 total_freeable += freeable;
636 }
637
638 seq_puts(s, "\n");
639 seq_printf(s, " %5s %5s %11lu %12lu %13lu %10lu %10lu %16s %8lu\n",
640 "Total", "", total_class_almost_full,
641 total_class_almost_empty, total_objs,
642 total_used_objs, total_pages, "", total_freeable);
643
644 return 0;
645}
646DEFINE_SHOW_ATTRIBUTE(zs_stats_size);
647
648static void zs_pool_stat_create(struct zs_pool *pool, const char *name)
649{
650 struct dentry *entry;
651
652 if (!zs_stat_root) {
653 pr_warn("no root stat dir, not creating <%s> stat dir\n", name);
654 return;
655 }
656
657 entry = debugfs_create_dir(name, zs_stat_root);
658 if (!entry) {
659 pr_warn("debugfs dir <%s> creation failed\n", name);
660 return;
661 }
662 pool->stat_dentry = entry;
663
664 entry = debugfs_create_file("classes", S_IFREG | 0444,
665 pool->stat_dentry, pool,
666 &zs_stats_size_fops);
667 if (!entry) {
668 pr_warn("%s: debugfs file entry <%s> creation failed\n",
669 name, "classes");
670 debugfs_remove_recursive(pool->stat_dentry);
671 pool->stat_dentry = NULL;
672 }
673}
674
675static void zs_pool_stat_destroy(struct zs_pool *pool)
676{
677 debugfs_remove_recursive(pool->stat_dentry);
678}
679
680#else /* CONFIG_ZSMALLOC_STAT */
681static void __init zs_stat_init(void)
682{
683}
684
685static void __exit zs_stat_exit(void)
686{
687}
688
689static inline void zs_pool_stat_create(struct zs_pool *pool, const char *name)
690{
691}
692
693static inline void zs_pool_stat_destroy(struct zs_pool *pool)
694{
695}
696#endif
697
698
699/*
700 * For each size class, zspages are divided into different groups
701 * depending on how "full" they are. This was done so that we could
702 * easily find empty or nearly empty zspages when we try to shrink
703 * the pool (not yet implemented). This function returns fullness
704 * status of the given page.
705 */
706static enum fullness_group get_fullness_group(struct size_class *class,
707 struct zspage *zspage)
708{
709 int inuse, objs_per_zspage;
710 enum fullness_group fg;
711
712 inuse = get_zspage_inuse(zspage);
713 objs_per_zspage = class->objs_per_zspage;
714
715 if (inuse == 0)
716 fg = ZS_EMPTY;
717 else if (inuse == objs_per_zspage)
718 fg = ZS_FULL;
719 else if (inuse <= 3 * objs_per_zspage / fullness_threshold_frac)
720 fg = ZS_ALMOST_EMPTY;
721 else
722 fg = ZS_ALMOST_FULL;
723
724 return fg;
725}
726
727/*
728 * Each size class maintains various freelists and zspages are assigned
729 * to one of these freelists based on the number of live objects they
730 * have. This functions inserts the given zspage into the freelist
731 * identified by <class, fullness_group>.
732 */
733static void insert_zspage(struct size_class *class,
734 struct zspage *zspage,
735 enum fullness_group fullness)
736{
737 struct zspage *head;
738
739 zs_stat_inc(class, fullness, 1);
740 head = list_first_entry_or_null(&class->fullness_list[fullness],
741 struct zspage, list);
742 /*
743 * We want to see more ZS_FULL pages and less almost empty/full.
744 * Put pages with higher ->inuse first.
745 */
746 if (head) {
747 if (get_zspage_inuse(zspage) < get_zspage_inuse(head)) {
748 list_add(&zspage->list, &head->list);
749 return;
750 }
751 }
752 list_add(&zspage->list, &class->fullness_list[fullness]);
753}
754
755/*
756 * This function removes the given zspage from the freelist identified
757 * by <class, fullness_group>.
758 */
759static void remove_zspage(struct size_class *class,
760 struct zspage *zspage,
761 enum fullness_group fullness)
762{
763 VM_BUG_ON(list_empty(&class->fullness_list[fullness]));
764 VM_BUG_ON(is_zspage_isolated(zspage));
765
766 list_del_init(&zspage->list);
767 zs_stat_dec(class, fullness, 1);
768}
769
770/*
771 * Each size class maintains zspages in different fullness groups depending
772 * on the number of live objects they contain. When allocating or freeing
773 * objects, the fullness status of the page can change, say, from ALMOST_FULL
774 * to ALMOST_EMPTY when freeing an object. This function checks if such
775 * a status change has occurred for the given page and accordingly moves the
776 * page from the freelist of the old fullness group to that of the new
777 * fullness group.
778 */
779static enum fullness_group fix_fullness_group(struct size_class *class,
780 struct zspage *zspage)
781{
782 int class_idx;
783 enum fullness_group currfg, newfg;
784
785 get_zspage_mapping(zspage, &class_idx, &currfg);
786 newfg = get_fullness_group(class, zspage);
787 if (newfg == currfg)
788 goto out;
789
790 if (!is_zspage_isolated(zspage)) {
791 remove_zspage(class, zspage, currfg);
792 insert_zspage(class, zspage, newfg);
793 }
794
795 set_zspage_mapping(zspage, class_idx, newfg);
796
797out:
798 return newfg;
799}
800
801/*
802 * We have to decide on how many pages to link together
803 * to form a zspage for each size class. This is important
804 * to reduce wastage due to unusable space left at end of
805 * each zspage which is given as:
806 * wastage = Zp % class_size
807 * usage = Zp - wastage
808 * where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ...
809 *
810 * For example, for size class of 3/8 * PAGE_SIZE, we should
811 * link together 3 PAGE_SIZE sized pages to form a zspage
812 * since then we can perfectly fit in 8 such objects.
813 */
814static int get_pages_per_zspage(int class_size)
815{
816 int i, max_usedpc = 0;
817 /* zspage order which gives maximum used size per KB */
818 int max_usedpc_order = 1;
819
820 for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) {
821 int zspage_size;
822 int waste, usedpc;
823
824 zspage_size = i * PAGE_SIZE;
825 waste = zspage_size % class_size;
826 usedpc = (zspage_size - waste) * 100 / zspage_size;
827
828 if (usedpc > max_usedpc) {
829 max_usedpc = usedpc;
830 max_usedpc_order = i;
831 }
832 }
833
834 return max_usedpc_order;
835}
836
837static struct zspage *get_zspage(struct page *page)
838{
839 struct zspage *zspage = (struct zspage *)page->private;
840
841 BUG_ON(zspage->magic != ZSPAGE_MAGIC);
842 return zspage;
843}
844
845static struct page *get_next_page(struct page *page)
846{
847 if (unlikely(PageHugeObject(page)))
848 return NULL;
849
850 return page->freelist;
851}
852
853/**
854 * obj_to_location - get (<page>, <obj_idx>) from encoded object value
855 * @obj: the encoded object value
856 * @page: page object resides in zspage
857 * @obj_idx: object index
858 */
859static void obj_to_location(unsigned long obj, struct page **page,
860 unsigned int *obj_idx)
861{
862 obj >>= OBJ_TAG_BITS;
863 *page = pfn_to_page(obj >> OBJ_INDEX_BITS);
864 *obj_idx = (obj & OBJ_INDEX_MASK);
865}
866
867/**
868 * location_to_obj - get obj value encoded from (<page>, <obj_idx>)
869 * @page: page object resides in zspage
870 * @obj_idx: object index
871 */
872static unsigned long location_to_obj(struct page *page, unsigned int obj_idx)
873{
874 unsigned long obj;
875
876 obj = page_to_pfn(page) << OBJ_INDEX_BITS;
877 obj |= obj_idx & OBJ_INDEX_MASK;
878 obj <<= OBJ_TAG_BITS;
879
880 return obj;
881}
882
883static unsigned long handle_to_obj(unsigned long handle)
884{
885 return *(unsigned long *)handle;
886}
887
888static unsigned long obj_to_head(struct page *page, void *obj)
889{
890 if (unlikely(PageHugeObject(page))) {
891 VM_BUG_ON_PAGE(!is_first_page(page), page);
892 return page->index;
893 } else
894 return *(unsigned long *)obj;
895}
896
897static inline int testpin_tag(unsigned long handle)
898{
899 return bit_spin_is_locked(HANDLE_PIN_BIT, (unsigned long *)handle);
900}
901
902static inline int trypin_tag(unsigned long handle)
903{
904 return bit_spin_trylock(HANDLE_PIN_BIT, (unsigned long *)handle);
905}
906
907static void pin_tag(unsigned long handle)
908{
909 bit_spin_lock(HANDLE_PIN_BIT, (unsigned long *)handle);
910}
911
912static void unpin_tag(unsigned long handle)
913{
914 bit_spin_unlock(HANDLE_PIN_BIT, (unsigned long *)handle);
915}
916
917static void reset_page(struct page *page)
918{
919 __ClearPageMovable(page);
920 ClearPagePrivate(page);
921 set_page_private(page, 0);
922 page_mapcount_reset(page);
923 ClearPageHugeObject(page);
924 page->freelist = NULL;
925}
926
927static int trylock_zspage(struct zspage *zspage)
928{
929 struct page *cursor, *fail;
930
931 for (cursor = get_first_page(zspage); cursor != NULL; cursor =
932 get_next_page(cursor)) {
933 if (!trylock_page(cursor)) {
934 fail = cursor;
935 goto unlock;
936 }
937 }
938
939 return 1;
940unlock:
941 for (cursor = get_first_page(zspage); cursor != fail; cursor =
942 get_next_page(cursor))
943 unlock_page(cursor);
944
945 return 0;
946}
947
948static void __free_zspage(struct zs_pool *pool, struct size_class *class,
949 struct zspage *zspage)
950{
951 struct page *page, *next;
952 enum fullness_group fg;
953 unsigned int class_idx;
954
955 get_zspage_mapping(zspage, &class_idx, &fg);
956
957 assert_spin_locked(&class->lock);
958
959 VM_BUG_ON(get_zspage_inuse(zspage));
960 VM_BUG_ON(fg != ZS_EMPTY);
961
962 next = page = get_first_page(zspage);
963 do {
964 VM_BUG_ON_PAGE(!PageLocked(page), page);
965 next = get_next_page(page);
966 reset_page(page);
967 unlock_page(page);
968 dec_zone_page_state(page, NR_ZSPAGES);
969 put_page(page);
970 page = next;
971 } while (page != NULL);
972
973 cache_free_zspage(pool, zspage);
974
975 zs_stat_dec(class, OBJ_ALLOCATED, class->objs_per_zspage);
976 atomic_long_sub(class->pages_per_zspage,
977 &pool->pages_allocated);
978}
979
980static void free_zspage(struct zs_pool *pool, struct size_class *class,
981 struct zspage *zspage)
982{
983 VM_BUG_ON(get_zspage_inuse(zspage));
984 VM_BUG_ON(list_empty(&zspage->list));
985
986 if (!trylock_zspage(zspage)) {
987 kick_deferred_free(pool);
988 return;
989 }
990
991 remove_zspage(class, zspage, ZS_EMPTY);
992 __free_zspage(pool, class, zspage);
993}
994
995/* Initialize a newly allocated zspage */
996static void init_zspage(struct size_class *class, struct zspage *zspage)
997{
998 unsigned int freeobj = 1;
999 unsigned long off = 0;
1000 struct page *page = get_first_page(zspage);
1001
1002 while (page) {
1003 struct page *next_page;
1004 struct link_free *link;
1005 void *vaddr;
1006
1007 set_first_obj_offset(page, off);
1008
1009 vaddr = kmap_atomic(page);
1010 link = (struct link_free *)vaddr + off / sizeof(*link);
1011
1012 while ((off += class->size) < PAGE_SIZE) {
1013 link->next = freeobj++ << OBJ_TAG_BITS;
1014 link += class->size / sizeof(*link);
1015 }
1016
1017 /*
1018 * We now come to the last (full or partial) object on this
1019 * page, which must point to the first object on the next
1020 * page (if present)
1021 */
1022 next_page = get_next_page(page);
1023 if (next_page) {
1024 link->next = freeobj++ << OBJ_TAG_BITS;
1025 } else {
1026 /*
1027 * Reset OBJ_TAG_BITS bit to last link to tell
1028 * whether it's allocated object or not.
1029 */
1030 link->next = -1UL << OBJ_TAG_BITS;
1031 }
1032 kunmap_atomic(vaddr);
1033 page = next_page;
1034 off %= PAGE_SIZE;
1035 }
1036
1037 set_freeobj(zspage, 0);
1038}
1039
1040static void create_page_chain(struct size_class *class, struct zspage *zspage,
1041 struct page *pages[])
1042{
1043 int i;
1044 struct page *page;
1045 struct page *prev_page = NULL;
1046 int nr_pages = class->pages_per_zspage;
1047
1048 /*
1049 * Allocate individual pages and link them together as:
1050 * 1. all pages are linked together using page->freelist
1051 * 2. each sub-page point to zspage using page->private
1052 *
1053 * we set PG_private to identify the first page (i.e. no other sub-page
1054 * has this flag set).
1055 */
1056 for (i = 0; i < nr_pages; i++) {
1057 page = pages[i];
1058 set_page_private(page, (unsigned long)zspage);
1059 page->freelist = NULL;
1060 if (i == 0) {
1061 zspage->first_page = page;
1062 SetPagePrivate(page);
1063 if (unlikely(class->objs_per_zspage == 1 &&
1064 class->pages_per_zspage == 1))
1065 SetPageHugeObject(page);
1066 } else {
1067 prev_page->freelist = page;
1068 }
1069 prev_page = page;
1070 }
1071}
1072
1073/*
1074 * Allocate a zspage for the given size class
1075 */
1076static struct zspage *alloc_zspage(struct zs_pool *pool,
1077 struct size_class *class,
1078 gfp_t gfp)
1079{
1080 int i;
1081 struct page *pages[ZS_MAX_PAGES_PER_ZSPAGE];
1082 struct zspage *zspage = cache_alloc_zspage(pool, gfp);
1083
1084 if (!zspage)
1085 return NULL;
1086
1087 memset(zspage, 0, sizeof(struct zspage));
1088 zspage->magic = ZSPAGE_MAGIC;
1089 migrate_lock_init(zspage);
1090
1091 for (i = 0; i < class->pages_per_zspage; i++) {
1092 struct page *page;
1093
1094 page = alloc_page(gfp);
1095 if (!page) {
1096 while (--i >= 0) {
1097 dec_zone_page_state(pages[i], NR_ZSPAGES);
1098 __free_page(pages[i]);
1099 }
1100 cache_free_zspage(pool, zspage);
1101 return NULL;
1102 }
1103
1104 inc_zone_page_state(page, NR_ZSPAGES);
1105 pages[i] = page;
1106 }
1107
1108 create_page_chain(class, zspage, pages);
1109 init_zspage(class, zspage);
1110
1111 return zspage;
1112}
1113
1114static struct zspage *find_get_zspage(struct size_class *class)
1115{
1116 int i;
1117 struct zspage *zspage;
1118
1119 for (i = ZS_ALMOST_FULL; i >= ZS_EMPTY; i--) {
1120 zspage = list_first_entry_or_null(&class->fullness_list[i],
1121 struct zspage, list);
1122 if (zspage)
1123 break;
1124 }
1125
1126 return zspage;
1127}
1128
1129#ifdef CONFIG_PGTABLE_MAPPING
1130static inline int __zs_cpu_up(struct mapping_area *area)
1131{
1132 /*
1133 * Make sure we don't leak memory if a cpu UP notification
1134 * and zs_init() race and both call zs_cpu_up() on the same cpu
1135 */
1136 if (area->vm)
1137 return 0;
1138 area->vm = alloc_vm_area(PAGE_SIZE * 2, NULL);
1139 if (!area->vm)
1140 return -ENOMEM;
1141 return 0;
1142}
1143
1144static inline void __zs_cpu_down(struct mapping_area *area)
1145{
1146 if (area->vm)
1147 free_vm_area(area->vm);
1148 area->vm = NULL;
1149}
1150
1151static inline void *__zs_map_object(struct mapping_area *area,
1152 struct page *pages[2], int off, int size)
1153{
1154 BUG_ON(map_vm_area(area->vm, PAGE_KERNEL, pages));
1155 area->vm_addr = area->vm->addr;
1156 return area->vm_addr + off;
1157}
1158
1159static inline void __zs_unmap_object(struct mapping_area *area,
1160 struct page *pages[2], int off, int size)
1161{
1162 unsigned long addr = (unsigned long)area->vm_addr;
1163
1164 unmap_kernel_range(addr, PAGE_SIZE * 2);
1165}
1166
1167#else /* CONFIG_PGTABLE_MAPPING */
1168
1169static inline int __zs_cpu_up(struct mapping_area *area)
1170{
1171 /*
1172 * Make sure we don't leak memory if a cpu UP notification
1173 * and zs_init() race and both call zs_cpu_up() on the same cpu
1174 */
1175 if (area->vm_buf)
1176 return 0;
1177 area->vm_buf = kmalloc(ZS_MAX_ALLOC_SIZE, GFP_KERNEL);
1178 if (!area->vm_buf)
1179 return -ENOMEM;
1180 return 0;
1181}
1182
1183static inline void __zs_cpu_down(struct mapping_area *area)
1184{
1185 kfree(area->vm_buf);
1186 area->vm_buf = NULL;
1187}
1188
1189static void *__zs_map_object(struct mapping_area *area,
1190 struct page *pages[2], int off, int size)
1191{
1192 int sizes[2];
1193 void *addr;
1194 char *buf = area->vm_buf;
1195
1196 /* disable page faults to match kmap_atomic() return conditions */
1197 pagefault_disable();
1198
1199 /* no read fastpath */
1200 if (area->vm_mm == ZS_MM_WO)
1201 goto out;
1202
1203 sizes[0] = PAGE_SIZE - off;
1204 sizes[1] = size - sizes[0];
1205
1206 /* copy object to per-cpu buffer */
1207 addr = kmap_atomic(pages[0]);
1208 memcpy(buf, addr + off, sizes[0]);
1209 kunmap_atomic(addr);
1210 addr = kmap_atomic(pages[1]);
1211 memcpy(buf + sizes[0], addr, sizes[1]);
1212 kunmap_atomic(addr);
1213out:
1214 return area->vm_buf;
1215}
1216
1217static void __zs_unmap_object(struct mapping_area *area,
1218 struct page *pages[2], int off, int size)
1219{
1220 int sizes[2];
1221 void *addr;
1222 char *buf;
1223
1224 /* no write fastpath */
1225 if (area->vm_mm == ZS_MM_RO)
1226 goto out;
1227
1228 buf = area->vm_buf;
1229 buf = buf + ZS_HANDLE_SIZE;
1230 size -= ZS_HANDLE_SIZE;
1231 off += ZS_HANDLE_SIZE;
1232
1233 sizes[0] = PAGE_SIZE - off;
1234 sizes[1] = size - sizes[0];
1235
1236 /* copy per-cpu buffer to object */
1237 addr = kmap_atomic(pages[0]);
1238 memcpy(addr + off, buf, sizes[0]);
1239 kunmap_atomic(addr);
1240 addr = kmap_atomic(pages[1]);
1241 memcpy(addr, buf + sizes[0], sizes[1]);
1242 kunmap_atomic(addr);
1243
1244out:
1245 /* enable page faults to match kunmap_atomic() return conditions */
1246 pagefault_enable();
1247}
1248
1249#endif /* CONFIG_PGTABLE_MAPPING */
1250
1251static int zs_cpu_prepare(unsigned int cpu)
1252{
1253 struct mapping_area *area;
1254
1255 area = &per_cpu(zs_map_area, cpu);
1256 return __zs_cpu_up(area);
1257}
1258
1259static int zs_cpu_dead(unsigned int cpu)
1260{
1261 struct mapping_area *area;
1262
1263 area = &per_cpu(zs_map_area, cpu);
1264 __zs_cpu_down(area);
1265 return 0;
1266}
1267
1268static bool can_merge(struct size_class *prev, int pages_per_zspage,
1269 int objs_per_zspage)
1270{
1271 if (prev->pages_per_zspage == pages_per_zspage &&
1272 prev->objs_per_zspage == objs_per_zspage)
1273 return true;
1274
1275 return false;
1276}
1277
1278static bool zspage_full(struct size_class *class, struct zspage *zspage)
1279{
1280 return get_zspage_inuse(zspage) == class->objs_per_zspage;
1281}
1282
1283unsigned long zs_get_total_pages(struct zs_pool *pool)
1284{
1285 return atomic_long_read(&pool->pages_allocated);
1286}
1287EXPORT_SYMBOL_GPL(zs_get_total_pages);
1288
1289/**
1290 * zs_map_object - get address of allocated object from handle.
1291 * @pool: pool from which the object was allocated
1292 * @handle: handle returned from zs_malloc
1293 * @mm: maping mode to use
1294 *
1295 * Before using an object allocated from zs_malloc, it must be mapped using
1296 * this function. When done with the object, it must be unmapped using
1297 * zs_unmap_object.
1298 *
1299 * Only one object can be mapped per cpu at a time. There is no protection
1300 * against nested mappings.
1301 *
1302 * This function returns with preemption and page faults disabled.
1303 */
1304void *zs_map_object(struct zs_pool *pool, unsigned long handle,
1305 enum zs_mapmode mm)
1306{
1307 struct zspage *zspage;
1308 struct page *page;
1309 unsigned long obj, off;
1310 unsigned int obj_idx;
1311
1312 unsigned int class_idx;
1313 enum fullness_group fg;
1314 struct size_class *class;
1315 struct mapping_area *area;
1316 struct page *pages[2];
1317 void *ret;
1318
1319 /*
1320 * Because we use per-cpu mapping areas shared among the
1321 * pools/users, we can't allow mapping in interrupt context
1322 * because it can corrupt another users mappings.
1323 */
1324 BUG_ON(in_interrupt());
1325
1326 /* From now on, migration cannot move the object */
1327 pin_tag(handle);
1328
1329 obj = handle_to_obj(handle);
1330 obj_to_location(obj, &page, &obj_idx);
1331 zspage = get_zspage(page);
1332
1333 /* migration cannot move any subpage in this zspage */
1334 migrate_read_lock(zspage);
1335
1336 get_zspage_mapping(zspage, &class_idx, &fg);
1337 class = pool->size_class[class_idx];
1338 off = (class->size * obj_idx) & ~PAGE_MASK;
1339
1340 area = &get_cpu_var(zs_map_area);
1341 area->vm_mm = mm;
1342 if (off + class->size <= PAGE_SIZE) {
1343 /* this object is contained entirely within a page */
1344 area->vm_addr = kmap_atomic(page);
1345 ret = area->vm_addr + off;
1346 goto out;
1347 }
1348
1349 /* this object spans two pages */
1350 pages[0] = page;
1351 pages[1] = get_next_page(page);
1352 BUG_ON(!pages[1]);
1353
1354 ret = __zs_map_object(area, pages, off, class->size);
1355out:
1356 if (likely(!PageHugeObject(page)))
1357 ret += ZS_HANDLE_SIZE;
1358
1359 return ret;
1360}
1361EXPORT_SYMBOL_GPL(zs_map_object);
1362
1363void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
1364{
1365 struct zspage *zspage;
1366 struct page *page;
1367 unsigned long obj, off;
1368 unsigned int obj_idx;
1369
1370 unsigned int class_idx;
1371 enum fullness_group fg;
1372 struct size_class *class;
1373 struct mapping_area *area;
1374
1375 obj = handle_to_obj(handle);
1376 obj_to_location(obj, &page, &obj_idx);
1377 zspage = get_zspage(page);
1378 get_zspage_mapping(zspage, &class_idx, &fg);
1379 class = pool->size_class[class_idx];
1380 off = (class->size * obj_idx) & ~PAGE_MASK;
1381
1382 area = this_cpu_ptr(&zs_map_area);
1383 if (off + class->size <= PAGE_SIZE)
1384 kunmap_atomic(area->vm_addr);
1385 else {
1386 struct page *pages[2];
1387
1388 pages[0] = page;
1389 pages[1] = get_next_page(page);
1390 BUG_ON(!pages[1]);
1391
1392 __zs_unmap_object(area, pages, off, class->size);
1393 }
1394 put_cpu_var(zs_map_area);
1395
1396 migrate_read_unlock(zspage);
1397 unpin_tag(handle);
1398}
1399EXPORT_SYMBOL_GPL(zs_unmap_object);
1400
1401/**
1402 * zs_huge_class_size() - Returns the size (in bytes) of the first huge
1403 * zsmalloc &size_class.
1404 * @pool: zsmalloc pool to use
1405 *
1406 * The function returns the size of the first huge class - any object of equal
1407 * or bigger size will be stored in zspage consisting of a single physical
1408 * page.
1409 *
1410 * Context: Any context.
1411 *
1412 * Return: the size (in bytes) of the first huge zsmalloc &size_class.
1413 */
1414size_t zs_huge_class_size(struct zs_pool *pool)
1415{
1416 return huge_class_size;
1417}
1418EXPORT_SYMBOL_GPL(zs_huge_class_size);
1419
1420static unsigned long obj_malloc(struct size_class *class,
1421 struct zspage *zspage, unsigned long handle)
1422{
1423 int i, nr_page, offset;
1424 unsigned long obj;
1425 struct link_free *link;
1426
1427 struct page *m_page;
1428 unsigned long m_offset;
1429 void *vaddr;
1430
1431 handle |= OBJ_ALLOCATED_TAG;
1432 obj = get_freeobj(zspage);
1433
1434 offset = obj * class->size;
1435 nr_page = offset >> PAGE_SHIFT;
1436 m_offset = offset & ~PAGE_MASK;
1437 m_page = get_first_page(zspage);
1438
1439 for (i = 0; i < nr_page; i++)
1440 m_page = get_next_page(m_page);
1441
1442 vaddr = kmap_atomic(m_page);
1443 link = (struct link_free *)vaddr + m_offset / sizeof(*link);
1444 set_freeobj(zspage, link->next >> OBJ_TAG_BITS);
1445 if (likely(!PageHugeObject(m_page)))
1446 /* record handle in the header of allocated chunk */
1447 link->handle = handle;
1448 else
1449 /* record handle to page->index */
1450 zspage->first_page->index = handle;
1451
1452 kunmap_atomic(vaddr);
1453 mod_zspage_inuse(zspage, 1);
1454 zs_stat_inc(class, OBJ_USED, 1);
1455
1456 obj = location_to_obj(m_page, obj);
1457
1458 return obj;
1459}
1460
1461
1462/**
1463 * zs_malloc - Allocate block of given size from pool.
1464 * @pool: pool to allocate from
1465 * @size: size of block to allocate
1466 * @gfp: gfp flags when allocating object
1467 *
1468 * On success, handle to the allocated object is returned,
1469 * otherwise 0.
1470 * Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
1471 */
1472unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
1473{
1474 unsigned long handle, obj;
1475 struct size_class *class;
1476 enum fullness_group newfg;
1477 struct zspage *zspage;
1478
1479 if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
1480 return 0;
1481
1482 handle = cache_alloc_handle(pool, gfp);
1483 if (!handle)
1484 return 0;
1485
1486 /* extra space in chunk to keep the handle */
1487 size += ZS_HANDLE_SIZE;
1488 class = pool->size_class[get_size_class_index(size)];
1489
1490 spin_lock(&class->lock);
1491 zspage = find_get_zspage(class);
1492 if (likely(zspage)) {
1493 obj = obj_malloc(class, zspage, handle);
1494 /* Now move the zspage to another fullness group, if required */
1495 fix_fullness_group(class, zspage);
1496 record_obj(handle, obj);
1497 spin_unlock(&class->lock);
1498
1499 return handle;
1500 }
1501
1502 spin_unlock(&class->lock);
1503
1504 zspage = alloc_zspage(pool, class, gfp);
1505 if (!zspage) {
1506 cache_free_handle(pool, handle);
1507 return 0;
1508 }
1509
1510 spin_lock(&class->lock);
1511 obj = obj_malloc(class, zspage, handle);
1512 newfg = get_fullness_group(class, zspage);
1513 insert_zspage(class, zspage, newfg);
1514 set_zspage_mapping(zspage, class->index, newfg);
1515 record_obj(handle, obj);
1516 atomic_long_add(class->pages_per_zspage,
1517 &pool->pages_allocated);
1518 zs_stat_inc(class, OBJ_ALLOCATED, class->objs_per_zspage);
1519
1520 /* We completely set up zspage so mark them as movable */
1521 SetZsPageMovable(pool, zspage);
1522 spin_unlock(&class->lock);
1523
1524 return handle;
1525}
1526EXPORT_SYMBOL_GPL(zs_malloc);
1527
1528static void obj_free(struct size_class *class, unsigned long obj)
1529{
1530 struct link_free *link;
1531 struct zspage *zspage;
1532 struct page *f_page;
1533 unsigned long f_offset;
1534 unsigned int f_objidx;
1535 void *vaddr;
1536
1537 obj &= ~OBJ_ALLOCATED_TAG;
1538 obj_to_location(obj, &f_page, &f_objidx);
1539 f_offset = (class->size * f_objidx) & ~PAGE_MASK;
1540 zspage = get_zspage(f_page);
1541
1542 vaddr = kmap_atomic(f_page);
1543
1544 /* Insert this object in containing zspage's freelist */
1545 link = (struct link_free *)(vaddr + f_offset);
1546 link->next = get_freeobj(zspage) << OBJ_TAG_BITS;
1547 kunmap_atomic(vaddr);
1548 set_freeobj(zspage, f_objidx);
1549 mod_zspage_inuse(zspage, -1);
1550 zs_stat_dec(class, OBJ_USED, 1);
1551}
1552
1553void zs_free(struct zs_pool *pool, unsigned long handle)
1554{
1555 struct zspage *zspage;
1556 struct page *f_page;
1557 unsigned long obj;
1558 unsigned int f_objidx;
1559 int class_idx;
1560 struct size_class *class;
1561 enum fullness_group fullness;
1562 bool isolated;
1563
1564 if (unlikely(!handle))
1565 return;
1566
1567 pin_tag(handle);
1568 obj = handle_to_obj(handle);
1569 obj_to_location(obj, &f_page, &f_objidx);
1570 zspage = get_zspage(f_page);
1571
1572 migrate_read_lock(zspage);
1573
1574 get_zspage_mapping(zspage, &class_idx, &fullness);
1575 class = pool->size_class[class_idx];
1576
1577 spin_lock(&class->lock);
1578 obj_free(class, obj);
1579 fullness = fix_fullness_group(class, zspage);
1580 if (fullness != ZS_EMPTY) {
1581 migrate_read_unlock(zspage);
1582 goto out;
1583 }
1584
1585 isolated = is_zspage_isolated(zspage);
1586 migrate_read_unlock(zspage);
1587 /* If zspage is isolated, zs_page_putback will free the zspage */
1588 if (likely(!isolated))
1589 free_zspage(pool, class, zspage);
1590out:
1591
1592 spin_unlock(&class->lock);
1593 unpin_tag(handle);
1594 cache_free_handle(pool, handle);
1595}
1596EXPORT_SYMBOL_GPL(zs_free);
1597
1598static void zs_object_copy(struct size_class *class, unsigned long dst,
1599 unsigned long src)
1600{
1601 struct page *s_page, *d_page;
1602 unsigned int s_objidx, d_objidx;
1603 unsigned long s_off, d_off;
1604 void *s_addr, *d_addr;
1605 int s_size, d_size, size;
1606 int written = 0;
1607
1608 s_size = d_size = class->size;
1609
1610 obj_to_location(src, &s_page, &s_objidx);
1611 obj_to_location(dst, &d_page, &d_objidx);
1612
1613 s_off = (class->size * s_objidx) & ~PAGE_MASK;
1614 d_off = (class->size * d_objidx) & ~PAGE_MASK;
1615
1616 if (s_off + class->size > PAGE_SIZE)
1617 s_size = PAGE_SIZE - s_off;
1618
1619 if (d_off + class->size > PAGE_SIZE)
1620 d_size = PAGE_SIZE - d_off;
1621
1622 s_addr = kmap_atomic(s_page);
1623 d_addr = kmap_atomic(d_page);
1624
1625 while (1) {
1626 size = min(s_size, d_size);
1627 memcpy(d_addr + d_off, s_addr + s_off, size);
1628 written += size;
1629
1630 if (written == class->size)
1631 break;
1632
1633 s_off += size;
1634 s_size -= size;
1635 d_off += size;
1636 d_size -= size;
1637
1638 if (s_off >= PAGE_SIZE) {
1639 kunmap_atomic(d_addr);
1640 kunmap_atomic(s_addr);
1641 s_page = get_next_page(s_page);
1642 s_addr = kmap_atomic(s_page);
1643 d_addr = kmap_atomic(d_page);
1644 s_size = class->size - written;
1645 s_off = 0;
1646 }
1647
1648 if (d_off >= PAGE_SIZE) {
1649 kunmap_atomic(d_addr);
1650 d_page = get_next_page(d_page);
1651 d_addr = kmap_atomic(d_page);
1652 d_size = class->size - written;
1653 d_off = 0;
1654 }
1655 }
1656
1657 kunmap_atomic(d_addr);
1658 kunmap_atomic(s_addr);
1659}
1660
1661/*
1662 * Find alloced object in zspage from index object and
1663 * return handle.
1664 */
1665static unsigned long find_alloced_obj(struct size_class *class,
1666 struct page *page, int *obj_idx)
1667{
1668 unsigned long head;
1669 int offset = 0;
1670 int index = *obj_idx;
1671 unsigned long handle = 0;
1672 void *addr = kmap_atomic(page);
1673
1674 offset = get_first_obj_offset(page);
1675 offset += class->size * index;
1676
1677 while (offset < PAGE_SIZE) {
1678 head = obj_to_head(page, addr + offset);
1679 if (head & OBJ_ALLOCATED_TAG) {
1680 handle = head & ~OBJ_ALLOCATED_TAG;
1681 if (trypin_tag(handle))
1682 break;
1683 handle = 0;
1684 }
1685
1686 offset += class->size;
1687 index++;
1688 }
1689
1690 kunmap_atomic(addr);
1691
1692 *obj_idx = index;
1693
1694 return handle;
1695}
1696
1697struct zs_compact_control {
1698 /* Source spage for migration which could be a subpage of zspage */
1699 struct page *s_page;
1700 /* Destination page for migration which should be a first page
1701 * of zspage. */
1702 struct page *d_page;
1703 /* Starting object index within @s_page which used for live object
1704 * in the subpage. */
1705 int obj_idx;
1706};
1707
1708static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
1709 struct zs_compact_control *cc)
1710{
1711 unsigned long used_obj, free_obj;
1712 unsigned long handle;
1713 struct page *s_page = cc->s_page;
1714 struct page *d_page = cc->d_page;
1715 int obj_idx = cc->obj_idx;
1716 int ret = 0;
1717
1718 while (1) {
1719 handle = find_alloced_obj(class, s_page, &obj_idx);
1720 if (!handle) {
1721 s_page = get_next_page(s_page);
1722 if (!s_page)
1723 break;
1724 obj_idx = 0;
1725 continue;
1726 }
1727
1728 /* Stop if there is no more space */
1729 if (zspage_full(class, get_zspage(d_page))) {
1730 unpin_tag(handle);
1731 ret = -ENOMEM;
1732 break;
1733 }
1734
1735 used_obj = handle_to_obj(handle);
1736 free_obj = obj_malloc(class, get_zspage(d_page), handle);
1737 zs_object_copy(class, free_obj, used_obj);
1738 obj_idx++;
1739 /*
1740 * record_obj updates handle's value to free_obj and it will
1741 * invalidate lock bit(ie, HANDLE_PIN_BIT) of handle, which
1742 * breaks synchronization using pin_tag(e,g, zs_free) so
1743 * let's keep the lock bit.
1744 */
1745 free_obj |= BIT(HANDLE_PIN_BIT);
1746 record_obj(handle, free_obj);
1747 unpin_tag(handle);
1748 obj_free(class, used_obj);
1749 }
1750
1751 /* Remember last position in this iteration */
1752 cc->s_page = s_page;
1753 cc->obj_idx = obj_idx;
1754
1755 return ret;
1756}
1757
1758static struct zspage *isolate_zspage(struct size_class *class, bool source)
1759{
1760 int i;
1761 struct zspage *zspage;
1762 enum fullness_group fg[2] = {ZS_ALMOST_EMPTY, ZS_ALMOST_FULL};
1763
1764 if (!source) {
1765 fg[0] = ZS_ALMOST_FULL;
1766 fg[1] = ZS_ALMOST_EMPTY;
1767 }
1768
1769 for (i = 0; i < 2; i++) {
1770 zspage = list_first_entry_or_null(&class->fullness_list[fg[i]],
1771 struct zspage, list);
1772 if (zspage) {
1773 VM_BUG_ON(is_zspage_isolated(zspage));
1774 remove_zspage(class, zspage, fg[i]);
1775 return zspage;
1776 }
1777 }
1778
1779 return zspage;
1780}
1781
1782/*
1783 * putback_zspage - add @zspage into right class's fullness list
1784 * @class: destination class
1785 * @zspage: target page
1786 *
1787 * Return @zspage's fullness_group
1788 */
1789static enum fullness_group putback_zspage(struct size_class *class,
1790 struct zspage *zspage)
1791{
1792 enum fullness_group fullness;
1793
1794 VM_BUG_ON(is_zspage_isolated(zspage));
1795
1796 fullness = get_fullness_group(class, zspage);
1797 insert_zspage(class, zspage, fullness);
1798 set_zspage_mapping(zspage, class->index, fullness);
1799
1800 return fullness;
1801}
1802
1803#ifdef CONFIG_COMPACTION
1804/*
1805 * To prevent zspage destroy during migration, zspage freeing should
1806 * hold locks of all pages in the zspage.
1807 */
1808static void lock_zspage(struct zspage *zspage)
1809{
1810 struct page *page = get_first_page(zspage);
1811
1812 do {
1813 lock_page(page);
1814 } while ((page = get_next_page(page)) != NULL);
1815}
1816
1817static struct dentry *zs_mount(struct file_system_type *fs_type,
1818 int flags, const char *dev_name, void *data)
1819{
1820 static const struct dentry_operations ops = {
1821 .d_dname = simple_dname,
1822 };
1823
1824 return mount_pseudo(fs_type, "zsmalloc:", NULL, &ops, ZSMALLOC_MAGIC);
1825}
1826
1827static struct file_system_type zsmalloc_fs = {
1828 .name = "zsmalloc",
1829 .mount = zs_mount,
1830 .kill_sb = kill_anon_super,
1831};
1832
1833static int zsmalloc_mount(void)
1834{
1835 int ret = 0;
1836
1837 zsmalloc_mnt = kern_mount(&zsmalloc_fs);
1838 if (IS_ERR(zsmalloc_mnt))
1839 ret = PTR_ERR(zsmalloc_mnt);
1840
1841 return ret;
1842}
1843
1844static void zsmalloc_unmount(void)
1845{
1846 kern_unmount(zsmalloc_mnt);
1847}
1848
1849static void migrate_lock_init(struct zspage *zspage)
1850{
1851 rwlock_init(&zspage->lock);
1852}
1853
1854static void migrate_read_lock(struct zspage *zspage)
1855{
1856 read_lock(&zspage->lock);
1857}
1858
1859static void migrate_read_unlock(struct zspage *zspage)
1860{
1861 read_unlock(&zspage->lock);
1862}
1863
1864static void migrate_write_lock(struct zspage *zspage)
1865{
1866 write_lock(&zspage->lock);
1867}
1868
1869static void migrate_write_unlock(struct zspage *zspage)
1870{
1871 write_unlock(&zspage->lock);
1872}
1873
1874/* Number of isolated subpage for *page migration* in this zspage */
1875static void inc_zspage_isolation(struct zspage *zspage)
1876{
1877 zspage->isolated++;
1878}
1879
1880static void dec_zspage_isolation(struct zspage *zspage)
1881{
1882 zspage->isolated--;
1883}
1884
1885static void replace_sub_page(struct size_class *class, struct zspage *zspage,
1886 struct page *newpage, struct page *oldpage)
1887{
1888 struct page *page;
1889 struct page *pages[ZS_MAX_PAGES_PER_ZSPAGE] = {NULL, };
1890 int idx = 0;
1891
1892 page = get_first_page(zspage);
1893 do {
1894 if (page == oldpage)
1895 pages[idx] = newpage;
1896 else
1897 pages[idx] = page;
1898 idx++;
1899 } while ((page = get_next_page(page)) != NULL);
1900
1901 create_page_chain(class, zspage, pages);
1902 set_first_obj_offset(newpage, get_first_obj_offset(oldpage));
1903 if (unlikely(PageHugeObject(oldpage)))
1904 newpage->index = oldpage->index;
1905 __SetPageMovable(newpage, page_mapping(oldpage));
1906}
1907
1908static bool zs_page_isolate(struct page *page, isolate_mode_t mode)
1909{
1910 struct zs_pool *pool;
1911 struct size_class *class;
1912 int class_idx;
1913 enum fullness_group fullness;
1914 struct zspage *zspage;
1915 struct address_space *mapping;
1916
1917 /*
1918 * Page is locked so zspage couldn't be destroyed. For detail, look at
1919 * lock_zspage in free_zspage.
1920 */
1921 VM_BUG_ON_PAGE(!PageMovable(page), page);
1922 VM_BUG_ON_PAGE(PageIsolated(page), page);
1923
1924 zspage = get_zspage(page);
1925
1926 /*
1927 * Without class lock, fullness could be stale while class_idx is okay
1928 * because class_idx is constant unless page is freed so we should get
1929 * fullness again under class lock.
1930 */
1931 get_zspage_mapping(zspage, &class_idx, &fullness);
1932 mapping = page_mapping(page);
1933 pool = mapping->private_data;
1934 class = pool->size_class[class_idx];
1935
1936 spin_lock(&class->lock);
1937 if (get_zspage_inuse(zspage) == 0) {
1938 spin_unlock(&class->lock);
1939 return false;
1940 }
1941
1942 /* zspage is isolated for object migration */
1943 if (list_empty(&zspage->list) && !is_zspage_isolated(zspage)) {
1944 spin_unlock(&class->lock);
1945 return false;
1946 }
1947
1948 /*
1949 * If this is first time isolation for the zspage, isolate zspage from
1950 * size_class to prevent further object allocation from the zspage.
1951 */
1952 if (!list_empty(&zspage->list) && !is_zspage_isolated(zspage)) {
1953 get_zspage_mapping(zspage, &class_idx, &fullness);
1954 remove_zspage(class, zspage, fullness);
1955 }
1956
1957 inc_zspage_isolation(zspage);
1958 spin_unlock(&class->lock);
1959
1960 return true;
1961}
1962
1963static int zs_page_migrate(struct address_space *mapping, struct page *newpage,
1964 struct page *page, enum migrate_mode mode)
1965{
1966 struct zs_pool *pool;
1967 struct size_class *class;
1968 int class_idx;
1969 enum fullness_group fullness;
1970 struct zspage *zspage;
1971 struct page *dummy;
1972 void *s_addr, *d_addr, *addr;
1973 int offset, pos;
1974 unsigned long handle, head;
1975 unsigned long old_obj, new_obj;
1976 unsigned int obj_idx;
1977 int ret = -EAGAIN;
1978
1979 /*
1980 * We cannot support the _NO_COPY case here, because copy needs to
1981 * happen under the zs lock, which does not work with
1982 * MIGRATE_SYNC_NO_COPY workflow.
1983 */
1984 if (mode == MIGRATE_SYNC_NO_COPY)
1985 return -EINVAL;
1986
1987 VM_BUG_ON_PAGE(!PageMovable(page), page);
1988 VM_BUG_ON_PAGE(!PageIsolated(page), page);
1989
1990 zspage = get_zspage(page);
1991
1992 /* Concurrent compactor cannot migrate any subpage in zspage */
1993 migrate_write_lock(zspage);
1994 get_zspage_mapping(zspage, &class_idx, &fullness);
1995 pool = mapping->private_data;
1996 class = pool->size_class[class_idx];
1997 offset = get_first_obj_offset(page);
1998
1999 spin_lock(&class->lock);
2000 if (!get_zspage_inuse(zspage)) {
2001 /*
2002 * Set "offset" to end of the page so that every loops
2003 * skips unnecessary object scanning.
2004 */
2005 offset = PAGE_SIZE;
2006 }
2007
2008 pos = offset;
2009 s_addr = kmap_atomic(page);
2010 while (pos < PAGE_SIZE) {
2011 head = obj_to_head(page, s_addr + pos);
2012 if (head & OBJ_ALLOCATED_TAG) {
2013 handle = head & ~OBJ_ALLOCATED_TAG;
2014 if (!trypin_tag(handle))
2015 goto unpin_objects;
2016 }
2017 pos += class->size;
2018 }
2019
2020 /*
2021 * Here, any user cannot access all objects in the zspage so let's move.
2022 */
2023 d_addr = kmap_atomic(newpage);
2024 memcpy(d_addr, s_addr, PAGE_SIZE);
2025 kunmap_atomic(d_addr);
2026
2027 for (addr = s_addr + offset; addr < s_addr + pos;
2028 addr += class->size) {
2029 head = obj_to_head(page, addr);
2030 if (head & OBJ_ALLOCATED_TAG) {
2031 handle = head & ~OBJ_ALLOCATED_TAG;
2032 if (!testpin_tag(handle))
2033 BUG();
2034
2035 old_obj = handle_to_obj(handle);
2036 obj_to_location(old_obj, &dummy, &obj_idx);
2037 new_obj = (unsigned long)location_to_obj(newpage,
2038 obj_idx);
2039 new_obj |= BIT(HANDLE_PIN_BIT);
2040 record_obj(handle, new_obj);
2041 }
2042 }
2043
2044 replace_sub_page(class, zspage, newpage, page);
2045 get_page(newpage);
2046
2047 dec_zspage_isolation(zspage);
2048
2049 /*
2050 * Page migration is done so let's putback isolated zspage to
2051 * the list if @page is final isolated subpage in the zspage.
2052 */
2053 if (!is_zspage_isolated(zspage))
2054 putback_zspage(class, zspage);
2055
2056 reset_page(page);
2057 put_page(page);
2058 page = newpage;
2059
2060 ret = MIGRATEPAGE_SUCCESS;
2061unpin_objects:
2062 for (addr = s_addr + offset; addr < s_addr + pos;
2063 addr += class->size) {
2064 head = obj_to_head(page, addr);
2065 if (head & OBJ_ALLOCATED_TAG) {
2066 handle = head & ~OBJ_ALLOCATED_TAG;
2067 if (!testpin_tag(handle))
2068 BUG();
2069 unpin_tag(handle);
2070 }
2071 }
2072 kunmap_atomic(s_addr);
2073 spin_unlock(&class->lock);
2074 migrate_write_unlock(zspage);
2075
2076 return ret;
2077}
2078
2079static void zs_page_putback(struct page *page)
2080{
2081 struct zs_pool *pool;
2082 struct size_class *class;
2083 int class_idx;
2084 enum fullness_group fg;
2085 struct address_space *mapping;
2086 struct zspage *zspage;
2087
2088 VM_BUG_ON_PAGE(!PageMovable(page), page);
2089 VM_BUG_ON_PAGE(!PageIsolated(page), page);
2090
2091 zspage = get_zspage(page);
2092 get_zspage_mapping(zspage, &class_idx, &fg);
2093 mapping = page_mapping(page);
2094 pool = mapping->private_data;
2095 class = pool->size_class[class_idx];
2096
2097 spin_lock(&class->lock);
2098 dec_zspage_isolation(zspage);
2099 if (!is_zspage_isolated(zspage)) {
2100 fg = putback_zspage(class, zspage);
2101 /*
2102 * Due to page_lock, we cannot free zspage immediately
2103 * so let's defer.
2104 */
2105 if (fg == ZS_EMPTY)
2106 schedule_work(&pool->free_work);
2107 }
2108 spin_unlock(&class->lock);
2109}
2110
2111static const struct address_space_operations zsmalloc_aops = {
2112 .isolate_page = zs_page_isolate,
2113 .migratepage = zs_page_migrate,
2114 .putback_page = zs_page_putback,
2115};
2116
2117static int zs_register_migration(struct zs_pool *pool)
2118{
2119 pool->inode = alloc_anon_inode(zsmalloc_mnt->mnt_sb);
2120 if (IS_ERR(pool->inode)) {
2121 pool->inode = NULL;
2122 return 1;
2123 }
2124
2125 pool->inode->i_mapping->private_data = pool;
2126 pool->inode->i_mapping->a_ops = &zsmalloc_aops;
2127 return 0;
2128}
2129
2130static void zs_unregister_migration(struct zs_pool *pool)
2131{
2132 flush_work(&pool->free_work);
2133 iput(pool->inode);
2134}
2135
2136/*
2137 * Caller should hold page_lock of all pages in the zspage
2138 * In here, we cannot use zspage meta data.
2139 */
2140static void async_free_zspage(struct work_struct *work)
2141{
2142 int i;
2143 struct size_class *class;
2144 unsigned int class_idx;
2145 enum fullness_group fullness;
2146 struct zspage *zspage, *tmp;
2147 LIST_HEAD(free_pages);
2148 struct zs_pool *pool = container_of(work, struct zs_pool,
2149 free_work);
2150
2151 for (i = 0; i < ZS_SIZE_CLASSES; i++) {
2152 class = pool->size_class[i];
2153 if (class->index != i)
2154 continue;
2155
2156 spin_lock(&class->lock);
2157 list_splice_init(&class->fullness_list[ZS_EMPTY], &free_pages);
2158 spin_unlock(&class->lock);
2159 }
2160
2161
2162 list_for_each_entry_safe(zspage, tmp, &free_pages, list) {
2163 list_del(&zspage->list);
2164 lock_zspage(zspage);
2165
2166 get_zspage_mapping(zspage, &class_idx, &fullness);
2167 VM_BUG_ON(fullness != ZS_EMPTY);
2168 class = pool->size_class[class_idx];
2169 spin_lock(&class->lock);
2170 __free_zspage(pool, pool->size_class[class_idx], zspage);
2171 spin_unlock(&class->lock);
2172 }
2173};
2174
2175static void kick_deferred_free(struct zs_pool *pool)
2176{
2177 schedule_work(&pool->free_work);
2178}
2179
2180static void init_deferred_free(struct zs_pool *pool)
2181{
2182 INIT_WORK(&pool->free_work, async_free_zspage);
2183}
2184
2185static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage)
2186{
2187 struct page *page = get_first_page(zspage);
2188
2189 do {
2190 WARN_ON(!trylock_page(page));
2191 __SetPageMovable(page, pool->inode->i_mapping);
2192 unlock_page(page);
2193 } while ((page = get_next_page(page)) != NULL);
2194}
2195#endif
2196
2197/*
2198 *
2199 * Based on the number of unused allocated objects calculate
2200 * and return the number of pages that we can free.
2201 */
2202static unsigned long zs_can_compact(struct size_class *class)
2203{
2204 unsigned long obj_wasted;
2205 unsigned long obj_allocated = zs_stat_get(class, OBJ_ALLOCATED);
2206 unsigned long obj_used = zs_stat_get(class, OBJ_USED);
2207
2208 if (obj_allocated <= obj_used)
2209 return 0;
2210
2211 obj_wasted = obj_allocated - obj_used;
2212 obj_wasted /= class->objs_per_zspage;
2213
2214 return obj_wasted * class->pages_per_zspage;
2215}
2216
2217static void __zs_compact(struct zs_pool *pool, struct size_class *class)
2218{
2219 struct zs_compact_control cc;
2220 struct zspage *src_zspage;
2221 struct zspage *dst_zspage = NULL;
2222
2223 spin_lock(&class->lock);
2224 while ((src_zspage = isolate_zspage(class, true))) {
2225
2226 if (!zs_can_compact(class))
2227 break;
2228
2229 cc.obj_idx = 0;
2230 cc.s_page = get_first_page(src_zspage);
2231
2232 while ((dst_zspage = isolate_zspage(class, false))) {
2233 cc.d_page = get_first_page(dst_zspage);
2234 /*
2235 * If there is no more space in dst_page, resched
2236 * and see if anyone had allocated another zspage.
2237 */
2238 if (!migrate_zspage(pool, class, &cc))
2239 break;
2240
2241 putback_zspage(class, dst_zspage);
2242 }
2243
2244 /* Stop if we couldn't find slot */
2245 if (dst_zspage == NULL)
2246 break;
2247
2248 putback_zspage(class, dst_zspage);
2249 if (putback_zspage(class, src_zspage) == ZS_EMPTY) {
2250 free_zspage(pool, class, src_zspage);
2251 pool->stats.pages_compacted += class->pages_per_zspage;
2252 }
2253 spin_unlock(&class->lock);
2254 cond_resched();
2255 spin_lock(&class->lock);
2256 }
2257
2258 if (src_zspage)
2259 putback_zspage(class, src_zspage);
2260
2261 spin_unlock(&class->lock);
2262}
2263
2264unsigned long zs_compact(struct zs_pool *pool)
2265{
2266 int i;
2267 struct size_class *class;
2268
2269 for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
2270 class = pool->size_class[i];
2271 if (!class)
2272 continue;
2273 if (class->index != i)
2274 continue;
2275 __zs_compact(pool, class);
2276 }
2277
2278 return pool->stats.pages_compacted;
2279}
2280EXPORT_SYMBOL_GPL(zs_compact);
2281
2282void zs_pool_stats(struct zs_pool *pool, struct zs_pool_stats *stats)
2283{
2284 memcpy(stats, &pool->stats, sizeof(struct zs_pool_stats));
2285}
2286EXPORT_SYMBOL_GPL(zs_pool_stats);
2287
2288static unsigned long zs_shrinker_scan(struct shrinker *shrinker,
2289 struct shrink_control *sc)
2290{
2291 unsigned long pages_freed;
2292 struct zs_pool *pool = container_of(shrinker, struct zs_pool,
2293 shrinker);
2294
2295 pages_freed = pool->stats.pages_compacted;
2296 /*
2297 * Compact classes and calculate compaction delta.
2298 * Can run concurrently with a manually triggered
2299 * (by user) compaction.
2300 */
2301 pages_freed = zs_compact(pool) - pages_freed;
2302
2303 return pages_freed ? pages_freed : SHRINK_STOP;
2304}
2305
2306static unsigned long zs_shrinker_count(struct shrinker *shrinker,
2307 struct shrink_control *sc)
2308{
2309 int i;
2310 struct size_class *class;
2311 unsigned long pages_to_free = 0;
2312 struct zs_pool *pool = container_of(shrinker, struct zs_pool,
2313 shrinker);
2314
2315 for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
2316 class = pool->size_class[i];
2317 if (!class)
2318 continue;
2319 if (class->index != i)
2320 continue;
2321
2322 pages_to_free += zs_can_compact(class);
2323 }
2324
2325 return pages_to_free;
2326}
2327
2328static void zs_unregister_shrinker(struct zs_pool *pool)
2329{
2330 unregister_shrinker(&pool->shrinker);
2331}
2332
2333static int zs_register_shrinker(struct zs_pool *pool)
2334{
2335 pool->shrinker.scan_objects = zs_shrinker_scan;
2336 pool->shrinker.count_objects = zs_shrinker_count;
2337 pool->shrinker.batch = 0;
2338 pool->shrinker.seeks = DEFAULT_SEEKS;
2339
2340 return register_shrinker(&pool->shrinker);
2341}
2342
2343/**
2344 * zs_create_pool - Creates an allocation pool to work from.
2345 * @name: pool name to be created
2346 *
2347 * This function must be called before anything when using
2348 * the zsmalloc allocator.
2349 *
2350 * On success, a pointer to the newly created pool is returned,
2351 * otherwise NULL.
2352 */
2353struct zs_pool *zs_create_pool(const char *name)
2354{
2355 int i;
2356 struct zs_pool *pool;
2357 struct size_class *prev_class = NULL;
2358
2359 pool = kzalloc(sizeof(*pool), GFP_KERNEL);
2360 if (!pool)
2361 return NULL;
2362
2363 init_deferred_free(pool);
2364
2365 pool->name = kstrdup(name, GFP_KERNEL);
2366 if (!pool->name)
2367 goto err;
2368
2369 if (create_cache(pool))
2370 goto err;
2371
2372 /*
2373 * Iterate reversely, because, size of size_class that we want to use
2374 * for merging should be larger or equal to current size.
2375 */
2376 for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
2377 int size;
2378 int pages_per_zspage;
2379 int objs_per_zspage;
2380 struct size_class *class;
2381 int fullness = 0;
2382
2383 size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA;
2384 if (size > ZS_MAX_ALLOC_SIZE)
2385 size = ZS_MAX_ALLOC_SIZE;
2386 pages_per_zspage = get_pages_per_zspage(size);
2387 objs_per_zspage = pages_per_zspage * PAGE_SIZE / size;
2388
2389 /*
2390 * We iterate from biggest down to smallest classes,
2391 * so huge_class_size holds the size of the first huge
2392 * class. Any object bigger than or equal to that will
2393 * endup in the huge class.
2394 */
2395 if (pages_per_zspage != 1 && objs_per_zspage != 1 &&
2396 !huge_class_size) {
2397 huge_class_size = size;
2398 /*
2399 * The object uses ZS_HANDLE_SIZE bytes to store the
2400 * handle. We need to subtract it, because zs_malloc()
2401 * unconditionally adds handle size before it performs
2402 * size class search - so object may be smaller than
2403 * huge class size, yet it still can end up in the huge
2404 * class because it grows by ZS_HANDLE_SIZE extra bytes
2405 * right before class lookup.
2406 */
2407 huge_class_size -= (ZS_HANDLE_SIZE - 1);
2408 }
2409
2410 /*
2411 * size_class is used for normal zsmalloc operation such
2412 * as alloc/free for that size. Although it is natural that we
2413 * have one size_class for each size, there is a chance that we
2414 * can get more memory utilization if we use one size_class for
2415 * many different sizes whose size_class have same
2416 * characteristics. So, we makes size_class point to
2417 * previous size_class if possible.
2418 */
2419 if (prev_class) {
2420 if (can_merge(prev_class, pages_per_zspage, objs_per_zspage)) {
2421 pool->size_class[i] = prev_class;
2422 continue;
2423 }
2424 }
2425
2426 class = kzalloc(sizeof(struct size_class), GFP_KERNEL);
2427 if (!class)
2428 goto err;
2429
2430 class->size = size;
2431 class->index = i;
2432 class->pages_per_zspage = pages_per_zspage;
2433 class->objs_per_zspage = objs_per_zspage;
2434 spin_lock_init(&class->lock);
2435 pool->size_class[i] = class;
2436 for (fullness = ZS_EMPTY; fullness < NR_ZS_FULLNESS;
2437 fullness++)
2438 INIT_LIST_HEAD(&class->fullness_list[fullness]);
2439
2440 prev_class = class;
2441 }
2442
2443 /* debug only, don't abort if it fails */
2444 zs_pool_stat_create(pool, name);
2445
2446 if (zs_register_migration(pool))
2447 goto err;
2448
2449 /*
2450 * Not critical since shrinker is only used to trigger internal
2451 * defragmentation of the pool which is pretty optional thing. If
2452 * registration fails we still can use the pool normally and user can
2453 * trigger compaction manually. Thus, ignore return code.
2454 */
2455 zs_register_shrinker(pool);
2456
2457 return pool;
2458
2459err:
2460 zs_destroy_pool(pool);
2461 return NULL;
2462}
2463EXPORT_SYMBOL_GPL(zs_create_pool);
2464
2465void zs_destroy_pool(struct zs_pool *pool)
2466{
2467 int i;
2468
2469 zs_unregister_shrinker(pool);
2470 zs_unregister_migration(pool);
2471 zs_pool_stat_destroy(pool);
2472
2473 for (i = 0; i < ZS_SIZE_CLASSES; i++) {
2474 int fg;
2475 struct size_class *class = pool->size_class[i];
2476
2477 if (!class)
2478 continue;
2479
2480 if (class->index != i)
2481 continue;
2482
2483 for (fg = ZS_EMPTY; fg < NR_ZS_FULLNESS; fg++) {
2484 if (!list_empty(&class->fullness_list[fg])) {
2485 pr_info("Freeing non-empty class with size %db, fullness group %d\n",
2486 class->size, fg);
2487 }
2488 }
2489 kfree(class);
2490 }
2491
2492 destroy_cache(pool);
2493 kfree(pool->name);
2494 kfree(pool);
2495}
2496EXPORT_SYMBOL_GPL(zs_destroy_pool);
2497
2498static int __init zs_init(void)
2499{
2500 int ret;
2501
2502 ret = zsmalloc_mount();
2503 if (ret)
2504 goto out;
2505
2506 ret = cpuhp_setup_state(CPUHP_MM_ZS_PREPARE, "mm/zsmalloc:prepare",
2507 zs_cpu_prepare, zs_cpu_dead);
2508 if (ret)
2509 goto hp_setup_fail;
2510
2511#ifdef CONFIG_ZPOOL
2512 zpool_register_driver(&zs_zpool_driver);
2513#endif
2514
2515 zs_stat_init();
2516
2517 return 0;
2518
2519hp_setup_fail:
2520 zsmalloc_unmount();
2521out:
2522 return ret;
2523}
2524
2525static void __exit zs_exit(void)
2526{
2527#ifdef CONFIG_ZPOOL
2528 zpool_unregister_driver(&zs_zpool_driver);
2529#endif
2530 zsmalloc_unmount();
2531 cpuhp_remove_state(CPUHP_MM_ZS_PREPARE);
2532
2533 zs_stat_exit();
2534}
2535
2536module_init(zs_init);
2537module_exit(zs_exit);
2538
2539MODULE_LICENSE("Dual BSD/GPL");
2540MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
2541