2 * zsmalloc memory allocator
4 * Copyright (C) 2011 Nitin Gupta
5 * Copyright (C) 2012, 2013 Minchan Kim
7 * This code is released using a dual license strategy: BSD/GPL
8 * You can choose the license that better fits your requirements.
10 * Released under the terms of 3-clause BSD License
11 * Released under the terms of GNU General Public License Version 2.0
15 * Following is how we use various fields and flags of underlying
16 * struct page(s) to form a zspage.
18 * Usage of struct page fields:
19 * page->first_page: points to the first component (0-order) page
20 * page->index (union with page->freelist): offset of the first object
21 * starting in this page. For the first page, this is
22 * always 0, so we use this field (aka freelist) to point
23 * to the first free object in zspage.
24 * page->lru: links together all component pages (except the first page)
27 * For _first_ page only:
29 * page->private (union with page->first_page): refers to the
30 * component page after the first page
31 * If the page is first_page for huge object, it stores handle.
32 * Look at size_class->huge.
33 * page->freelist: points to the first free object in zspage.
34 * Free objects are linked together using in-place
36 * page->objects: maximum number of objects we can store in this
37 * zspage (class->zspage_order * PAGE_SIZE / class->size)
38 * page->lru: links together first pages of various zspages.
39 * Basically forming list of zspages in a fullness group.
40 * page->mapping: class index and fullness group of the zspage
42 * Usage of struct page flags:
43 * PG_private: identifies the first component page
44 * PG_private2: identifies the last component page
48 #include <linux/module.h>
49 #include <linux/kernel.h>
50 #include <linux/sched.h>
51 #include <linux/bitops.h>
52 #include <linux/errno.h>
53 #include <linux/highmem.h>
54 #include <linux/string.h>
55 #include <linux/slab.h>
56 #include <asm/tlbflush.h>
57 #include <asm/pgtable.h>
58 #include <linux/cpumask.h>
59 #include <linux/cpu.h>
60 #include <linux/vmalloc.h>
61 #include <linux/hardirq.h>
62 #include <linux/spinlock.h>
63 #include <linux/types.h>
64 #include <linux/debugfs.h>
65 #include <linux/zsmalloc.h>
66 #include <linux/zpool.h>
69 * This must be power of 2 and greater than of equal to sizeof(link_free).
70 * These two conditions ensure that any 'struct link_free' itself doesn't
71 * span more than 1 page which avoids complex case of mapping 2 pages simply
72 * to restore link_free pointer values.
77 * A single 'zspage' is composed of up to 2^N discontiguous 0-order (single)
78 * pages. ZS_MAX_ZSPAGE_ORDER defines upper limit on N.
80 #define ZS_MAX_ZSPAGE_ORDER 2
81 #define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER)
83 #define ZS_HANDLE_SIZE (sizeof(unsigned long))
86 * Object location (<PFN>, <obj_idx>) is encoded as
87 * as single (unsigned long) handle value.
89 * Note that object index <obj_idx> is relative to system
90 * page <PFN> it is stored in, so for each sub-page belonging
91 * to a zspage, obj_idx starts with 0.
93 * This is made more complicated by various memory models and PAE.
96 #ifndef MAX_PHYSMEM_BITS
97 #ifdef CONFIG_HIGHMEM64G
98 #define MAX_PHYSMEM_BITS 36
99 #else /* !CONFIG_HIGHMEM64G */
101 * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just
104 #define MAX_PHYSMEM_BITS BITS_PER_LONG
107 #define _PFN_BITS (MAX_PHYSMEM_BITS - PAGE_SHIFT)
110 * Memory for allocating for handle keeps object position by
111 * encoding <page, obj_idx> and the encoded value has a room
112 * in least bit(ie, look at obj_to_location).
113 * We use the bit to synchronize between object access by
114 * user and migration.
116 #define HANDLE_PIN_BIT 0
119 * Head in allocated object should have OBJ_ALLOCATED_TAG
120 * to identify the object was allocated or not.
121 * It's okay to add the status bit in the least bit because
122 * header keeps handle which is 4byte-aligned address so we
123 * have room for two bit at least.
125 #define OBJ_ALLOCATED_TAG 1
126 #define OBJ_TAG_BITS 1
127 #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
128 #define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
130 #define MAX(a, b) ((a) >= (b) ? (a) : (b))
131 /* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
132 #define ZS_MIN_ALLOC_SIZE \
133 MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
134 /* each chunk includes extra space to keep handle */
135 #define ZS_MAX_ALLOC_SIZE PAGE_SIZE
138 * On systems with 4K page size, this gives 255 size classes! There is a
140 * - Large number of size classes is potentially wasteful as free page are
141 * spread across these classes
142 * - Small number of size classes causes large internal fragmentation
143 * - Probably its better to use specific size classes (empirically
144 * determined). NOTE: all those class sizes must be set as multiple of
145 * ZS_ALIGN to make sure link_free itself never has to span 2 pages.
147 * ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN
150 #define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> 8)
153 * We do not maintain any list for completely empty or full pages
155 enum fullness_group
{
158 _ZS_NR_FULLNESS_GROUPS
,
172 struct zs_size_stat
{
173 unsigned long objs
[NR_ZS_STAT_TYPE
];
176 #ifdef CONFIG_ZSMALLOC_STAT
177 static struct dentry
*zs_stat_root
;
181 * number of size_classes
183 static int zs_size_classes
;
186 * We assign a page to ZS_ALMOST_EMPTY fullness group when:
188 * n = number of allocated objects
189 * N = total number of objects zspage can store
190 * f = fullness_threshold_frac
192 * Similarly, we assign zspage to:
193 * ZS_ALMOST_FULL when n > N / f
194 * ZS_EMPTY when n == 0
195 * ZS_FULL when n == N
197 * (see: fix_fullness_group())
199 static const int fullness_threshold_frac
= 4;
203 struct page
*fullness_list
[_ZS_NR_FULLNESS_GROUPS
];
205 * Size of objects stored in this class. Must be multiple
211 /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
212 int pages_per_zspage
;
213 struct zs_size_stat stats
;
215 /* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
220 * Placed within free objects to form a singly linked list.
221 * For every zspage, first_page->freelist gives head of this list.
223 * This must be power of 2 and less than or equal to ZS_ALIGN
228 * Position of next free chunk (encodes <PFN, obj_idx>)
229 * It's valid for non-allocated object
233 * Handle of allocated object.
235 unsigned long handle
;
242 struct size_class
**size_class
;
243 struct kmem_cache
*handle_cachep
;
245 gfp_t flags
; /* allocation flags used when growing pool */
246 atomic_long_t pages_allocated
;
248 #ifdef CONFIG_ZSMALLOC_STAT
249 struct dentry
*stat_dentry
;
254 * A zspage's class index and fullness group
255 * are encoded in its (first)page->mapping
257 #define CLASS_IDX_BITS 28
258 #define FULLNESS_BITS 4
259 #define CLASS_IDX_MASK ((1 << CLASS_IDX_BITS) - 1)
260 #define FULLNESS_MASK ((1 << FULLNESS_BITS) - 1)
262 struct mapping_area
{
263 #ifdef CONFIG_PGTABLE_MAPPING
264 struct vm_struct
*vm
; /* vm area for mapping object that span pages */
266 char *vm_buf
; /* copy buffer for objects that span pages */
268 char *vm_addr
; /* address of kmap_atomic()'ed pages */
269 enum zs_mapmode vm_mm
; /* mapping mode */
273 static int create_handle_cache(struct zs_pool
*pool
)
275 pool
->handle_cachep
= kmem_cache_create("zs_handle", ZS_HANDLE_SIZE
,
277 return pool
->handle_cachep
? 0 : 1;
280 static void destroy_handle_cache(struct zs_pool
*pool
)
282 if (pool
->handle_cachep
)
283 kmem_cache_destroy(pool
->handle_cachep
);
286 static unsigned long alloc_handle(struct zs_pool
*pool
)
288 return (unsigned long)kmem_cache_alloc(pool
->handle_cachep
,
289 pool
->flags
& ~__GFP_HIGHMEM
);
292 static void free_handle(struct zs_pool
*pool
, unsigned long handle
)
294 kmem_cache_free(pool
->handle_cachep
, (void *)handle
);
297 static void record_obj(unsigned long handle
, unsigned long obj
)
299 *(unsigned long *)handle
= obj
;
306 static void *zs_zpool_create(char *name
, gfp_t gfp
, struct zpool_ops
*zpool_ops
,
309 return zs_create_pool(name
, gfp
);
312 static void zs_zpool_destroy(void *pool
)
314 zs_destroy_pool(pool
);
317 static int zs_zpool_malloc(void *pool
, size_t size
, gfp_t gfp
,
318 unsigned long *handle
)
320 *handle
= zs_malloc(pool
, size
);
321 return *handle
? 0 : -1;
323 static void zs_zpool_free(void *pool
, unsigned long handle
)
325 zs_free(pool
, handle
);
328 static int zs_zpool_shrink(void *pool
, unsigned int pages
,
329 unsigned int *reclaimed
)
334 static void *zs_zpool_map(void *pool
, unsigned long handle
,
335 enum zpool_mapmode mm
)
337 enum zs_mapmode zs_mm
;
346 case ZPOOL_MM_RW
: /* fallthru */
352 return zs_map_object(pool
, handle
, zs_mm
);
354 static void zs_zpool_unmap(void *pool
, unsigned long handle
)
356 zs_unmap_object(pool
, handle
);
359 static u64
zs_zpool_total_size(void *pool
)
361 return zs_get_total_pages(pool
) << PAGE_SHIFT
;
364 static struct zpool_driver zs_zpool_driver
= {
366 .owner
= THIS_MODULE
,
367 .create
= zs_zpool_create
,
368 .destroy
= zs_zpool_destroy
,
369 .malloc
= zs_zpool_malloc
,
370 .free
= zs_zpool_free
,
371 .shrink
= zs_zpool_shrink
,
373 .unmap
= zs_zpool_unmap
,
374 .total_size
= zs_zpool_total_size
,
377 MODULE_ALIAS("zpool-zsmalloc");
378 #endif /* CONFIG_ZPOOL */
380 static unsigned int get_maxobj_per_zspage(int size
, int pages_per_zspage
)
382 return pages_per_zspage
* PAGE_SIZE
/ size
;
385 /* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
386 static DEFINE_PER_CPU(struct mapping_area
, zs_map_area
);
388 static int is_first_page(struct page
*page
)
390 return PagePrivate(page
);
393 static int is_last_page(struct page
*page
)
395 return PagePrivate2(page
);
398 static void get_zspage_mapping(struct page
*page
, unsigned int *class_idx
,
399 enum fullness_group
*fullness
)
402 BUG_ON(!is_first_page(page
));
404 m
= (unsigned long)page
->mapping
;
405 *fullness
= m
& FULLNESS_MASK
;
406 *class_idx
= (m
>> FULLNESS_BITS
) & CLASS_IDX_MASK
;
409 static void set_zspage_mapping(struct page
*page
, unsigned int class_idx
,
410 enum fullness_group fullness
)
413 BUG_ON(!is_first_page(page
));
415 m
= ((class_idx
& CLASS_IDX_MASK
) << FULLNESS_BITS
) |
416 (fullness
& FULLNESS_MASK
);
417 page
->mapping
= (struct address_space
*)m
;
421 * zsmalloc divides the pool into various size classes where each
422 * class maintains a list of zspages where each zspage is divided
423 * into equal sized chunks. Each allocation falls into one of these
424 * classes depending on its size. This function returns index of the
425 * size class which has chunk size big enough to hold the give size.
427 static int get_size_class_index(int size
)
431 if (likely(size
> ZS_MIN_ALLOC_SIZE
))
432 idx
= DIV_ROUND_UP(size
- ZS_MIN_ALLOC_SIZE
,
433 ZS_SIZE_CLASS_DELTA
);
435 return min(zs_size_classes
- 1, idx
);
438 static inline void zs_stat_inc(struct size_class
*class,
439 enum zs_stat_type type
, unsigned long cnt
)
441 class->stats
.objs
[type
] += cnt
;
444 static inline void zs_stat_dec(struct size_class
*class,
445 enum zs_stat_type type
, unsigned long cnt
)
447 class->stats
.objs
[type
] -= cnt
;
450 static inline unsigned long zs_stat_get(struct size_class
*class,
451 enum zs_stat_type type
)
453 return class->stats
.objs
[type
];
456 #ifdef CONFIG_ZSMALLOC_STAT
458 static int __init
zs_stat_init(void)
460 if (!debugfs_initialized())
463 zs_stat_root
= debugfs_create_dir("zsmalloc", NULL
);
470 static void __exit
zs_stat_exit(void)
472 debugfs_remove_recursive(zs_stat_root
);
475 static int zs_stats_size_show(struct seq_file
*s
, void *v
)
478 struct zs_pool
*pool
= s
->private;
479 struct size_class
*class;
481 unsigned long class_almost_full
, class_almost_empty
;
482 unsigned long obj_allocated
, obj_used
, pages_used
;
483 unsigned long total_class_almost_full
= 0, total_class_almost_empty
= 0;
484 unsigned long total_objs
= 0, total_used_objs
= 0, total_pages
= 0;
486 seq_printf(s
, " %5s %5s %11s %12s %13s %10s %10s %16s\n",
487 "class", "size", "almost_full", "almost_empty",
488 "obj_allocated", "obj_used", "pages_used",
491 for (i
= 0; i
< zs_size_classes
; i
++) {
492 class = pool
->size_class
[i
];
494 if (class->index
!= i
)
497 spin_lock(&class->lock
);
498 class_almost_full
= zs_stat_get(class, CLASS_ALMOST_FULL
);
499 class_almost_empty
= zs_stat_get(class, CLASS_ALMOST_EMPTY
);
500 obj_allocated
= zs_stat_get(class, OBJ_ALLOCATED
);
501 obj_used
= zs_stat_get(class, OBJ_USED
);
502 spin_unlock(&class->lock
);
504 objs_per_zspage
= get_maxobj_per_zspage(class->size
,
505 class->pages_per_zspage
);
506 pages_used
= obj_allocated
/ objs_per_zspage
*
507 class->pages_per_zspage
;
509 seq_printf(s
, " %5u %5u %11lu %12lu %13lu %10lu %10lu %16d\n",
510 i
, class->size
, class_almost_full
, class_almost_empty
,
511 obj_allocated
, obj_used
, pages_used
,
512 class->pages_per_zspage
);
514 total_class_almost_full
+= class_almost_full
;
515 total_class_almost_empty
+= class_almost_empty
;
516 total_objs
+= obj_allocated
;
517 total_used_objs
+= obj_used
;
518 total_pages
+= pages_used
;
522 seq_printf(s
, " %5s %5s %11lu %12lu %13lu %10lu %10lu\n",
523 "Total", "", total_class_almost_full
,
524 total_class_almost_empty
, total_objs
,
525 total_used_objs
, total_pages
);
530 static int zs_stats_size_open(struct inode
*inode
, struct file
*file
)
532 return single_open(file
, zs_stats_size_show
, inode
->i_private
);
535 static const struct file_operations zs_stat_size_ops
= {
536 .open
= zs_stats_size_open
,
539 .release
= single_release
,
542 static int zs_pool_stat_create(char *name
, struct zs_pool
*pool
)
544 struct dentry
*entry
;
549 entry
= debugfs_create_dir(name
, zs_stat_root
);
551 pr_warn("debugfs dir <%s> creation failed\n", name
);
554 pool
->stat_dentry
= entry
;
556 entry
= debugfs_create_file("classes", S_IFREG
| S_IRUGO
,
557 pool
->stat_dentry
, pool
, &zs_stat_size_ops
);
559 pr_warn("%s: debugfs file entry <%s> creation failed\n",
567 static void zs_pool_stat_destroy(struct zs_pool
*pool
)
569 debugfs_remove_recursive(pool
->stat_dentry
);
572 #else /* CONFIG_ZSMALLOC_STAT */
573 static int __init
zs_stat_init(void)
578 static void __exit
zs_stat_exit(void)
582 static inline int zs_pool_stat_create(char *name
, struct zs_pool
*pool
)
587 static inline void zs_pool_stat_destroy(struct zs_pool
*pool
)
594 * For each size class, zspages are divided into different groups
595 * depending on how "full" they are. This was done so that we could
596 * easily find empty or nearly empty zspages when we try to shrink
597 * the pool (not yet implemented). This function returns fullness
598 * status of the given page.
600 static enum fullness_group
get_fullness_group(struct page
*page
)
602 int inuse
, max_objects
;
603 enum fullness_group fg
;
604 BUG_ON(!is_first_page(page
));
607 max_objects
= page
->objects
;
611 else if (inuse
== max_objects
)
613 else if (inuse
<= 3 * max_objects
/ fullness_threshold_frac
)
614 fg
= ZS_ALMOST_EMPTY
;
622 * Each size class maintains various freelists and zspages are assigned
623 * to one of these freelists based on the number of live objects they
624 * have. This functions inserts the given zspage into the freelist
625 * identified by <class, fullness_group>.
627 static void insert_zspage(struct page
*page
, struct size_class
*class,
628 enum fullness_group fullness
)
632 BUG_ON(!is_first_page(page
));
634 if (fullness
>= _ZS_NR_FULLNESS_GROUPS
)
637 head
= &class->fullness_list
[fullness
];
639 list_add_tail(&page
->lru
, &(*head
)->lru
);
642 zs_stat_inc(class, fullness
== ZS_ALMOST_EMPTY
?
643 CLASS_ALMOST_EMPTY
: CLASS_ALMOST_FULL
, 1);
647 * This function removes the given zspage from the freelist identified
648 * by <class, fullness_group>.
650 static void remove_zspage(struct page
*page
, struct size_class
*class,
651 enum fullness_group fullness
)
655 BUG_ON(!is_first_page(page
));
657 if (fullness
>= _ZS_NR_FULLNESS_GROUPS
)
660 head
= &class->fullness_list
[fullness
];
662 if (list_empty(&(*head
)->lru
))
664 else if (*head
== page
)
665 *head
= (struct page
*)list_entry((*head
)->lru
.next
,
668 list_del_init(&page
->lru
);
669 zs_stat_dec(class, fullness
== ZS_ALMOST_EMPTY
?
670 CLASS_ALMOST_EMPTY
: CLASS_ALMOST_FULL
, 1);
674 * Each size class maintains zspages in different fullness groups depending
675 * on the number of live objects they contain. When allocating or freeing
676 * objects, the fullness status of the page can change, say, from ALMOST_FULL
677 * to ALMOST_EMPTY when freeing an object. This function checks if such
678 * a status change has occurred for the given page and accordingly moves the
679 * page from the freelist of the old fullness group to that of the new
682 static enum fullness_group
fix_fullness_group(struct size_class
*class,
686 enum fullness_group currfg
, newfg
;
688 BUG_ON(!is_first_page(page
));
690 get_zspage_mapping(page
, &class_idx
, &currfg
);
691 newfg
= get_fullness_group(page
);
695 remove_zspage(page
, class, currfg
);
696 insert_zspage(page
, class, newfg
);
697 set_zspage_mapping(page
, class_idx
, newfg
);
704 * We have to decide on how many pages to link together
705 * to form a zspage for each size class. This is important
706 * to reduce wastage due to unusable space left at end of
707 * each zspage which is given as:
708 * wastage = Zp % class_size
709 * usage = Zp - wastage
710 * where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ...
712 * For example, for size class of 3/8 * PAGE_SIZE, we should
713 * link together 3 PAGE_SIZE sized pages to form a zspage
714 * since then we can perfectly fit in 8 such objects.
716 static int get_pages_per_zspage(int class_size
)
718 int i
, max_usedpc
= 0;
719 /* zspage order which gives maximum used size per KB */
720 int max_usedpc_order
= 1;
722 for (i
= 1; i
<= ZS_MAX_PAGES_PER_ZSPAGE
; i
++) {
726 zspage_size
= i
* PAGE_SIZE
;
727 waste
= zspage_size
% class_size
;
728 usedpc
= (zspage_size
- waste
) * 100 / zspage_size
;
730 if (usedpc
> max_usedpc
) {
732 max_usedpc_order
= i
;
736 return max_usedpc_order
;
740 * A single 'zspage' is composed of many system pages which are
741 * linked together using fields in struct page. This function finds
742 * the first/head page, given any component page of a zspage.
744 static struct page
*get_first_page(struct page
*page
)
746 if (is_first_page(page
))
749 return page
->first_page
;
752 static struct page
*get_next_page(struct page
*page
)
756 if (is_last_page(page
))
758 else if (is_first_page(page
))
759 next
= (struct page
*)page_private(page
);
761 next
= list_entry(page
->lru
.next
, struct page
, lru
);
767 * Encode <page, obj_idx> as a single handle value.
768 * We use the least bit of handle for tagging.
770 static void *location_to_obj(struct page
*page
, unsigned long obj_idx
)
779 obj
= page_to_pfn(page
) << OBJ_INDEX_BITS
;
780 obj
|= ((obj_idx
) & OBJ_INDEX_MASK
);
781 obj
<<= OBJ_TAG_BITS
;
787 * Decode <page, obj_idx> pair from the given object handle. We adjust the
788 * decoded obj_idx back to its original value since it was adjusted in
791 static void obj_to_location(unsigned long obj
, struct page
**page
,
792 unsigned long *obj_idx
)
794 obj
>>= OBJ_TAG_BITS
;
795 *page
= pfn_to_page(obj
>> OBJ_INDEX_BITS
);
796 *obj_idx
= (obj
& OBJ_INDEX_MASK
);
799 static unsigned long handle_to_obj(unsigned long handle
)
801 return *(unsigned long *)handle
;
804 static unsigned long obj_to_head(struct size_class
*class, struct page
*page
,
808 VM_BUG_ON(!is_first_page(page
));
809 return *(unsigned long *)page_private(page
);
811 return *(unsigned long *)obj
;
814 static unsigned long obj_idx_to_offset(struct page
*page
,
815 unsigned long obj_idx
, int class_size
)
817 unsigned long off
= 0;
819 if (!is_first_page(page
))
822 return off
+ obj_idx
* class_size
;
825 static inline int trypin_tag(unsigned long handle
)
827 unsigned long *ptr
= (unsigned long *)handle
;
829 return !test_and_set_bit_lock(HANDLE_PIN_BIT
, ptr
);
832 static void pin_tag(unsigned long handle
)
834 while (!trypin_tag(handle
));
837 static void unpin_tag(unsigned long handle
)
839 unsigned long *ptr
= (unsigned long *)handle
;
841 clear_bit_unlock(HANDLE_PIN_BIT
, ptr
);
844 static void reset_page(struct page
*page
)
846 clear_bit(PG_private
, &page
->flags
);
847 clear_bit(PG_private_2
, &page
->flags
);
848 set_page_private(page
, 0);
849 page
->mapping
= NULL
;
850 page
->freelist
= NULL
;
851 page_mapcount_reset(page
);
854 static void free_zspage(struct page
*first_page
)
856 struct page
*nextp
, *tmp
, *head_extra
;
858 BUG_ON(!is_first_page(first_page
));
859 BUG_ON(first_page
->inuse
);
861 head_extra
= (struct page
*)page_private(first_page
);
863 reset_page(first_page
);
864 __free_page(first_page
);
866 /* zspage with only 1 system page */
870 list_for_each_entry_safe(nextp
, tmp
, &head_extra
->lru
, lru
) {
871 list_del(&nextp
->lru
);
875 reset_page(head_extra
);
876 __free_page(head_extra
);
879 /* Initialize a newly allocated zspage */
880 static void init_zspage(struct page
*first_page
, struct size_class
*class)
882 unsigned long off
= 0;
883 struct page
*page
= first_page
;
885 BUG_ON(!is_first_page(first_page
));
887 struct page
*next_page
;
888 struct link_free
*link
;
893 * page->index stores offset of first object starting
894 * in the page. For the first page, this is always 0,
895 * so we use first_page->index (aka ->freelist) to store
896 * head of corresponding zspage's freelist.
898 if (page
!= first_page
)
901 vaddr
= kmap_atomic(page
);
902 link
= (struct link_free
*)vaddr
+ off
/ sizeof(*link
);
904 while ((off
+= class->size
) < PAGE_SIZE
) {
905 link
->next
= location_to_obj(page
, i
++);
906 link
+= class->size
/ sizeof(*link
);
910 * We now come to the last (full or partial) object on this
911 * page, which must point to the first object on the next
914 next_page
= get_next_page(page
);
915 link
->next
= location_to_obj(next_page
, 0);
916 kunmap_atomic(vaddr
);
923 * Allocate a zspage for the given size class
925 static struct page
*alloc_zspage(struct size_class
*class, gfp_t flags
)
928 struct page
*first_page
= NULL
, *uninitialized_var(prev_page
);
931 * Allocate individual pages and link them together as:
932 * 1. first page->private = first sub-page
933 * 2. all sub-pages are linked together using page->lru
934 * 3. each sub-page is linked to the first page using page->first_page
936 * For each size class, First/Head pages are linked together using
937 * page->lru. Also, we set PG_private to identify the first page
938 * (i.e. no other sub-page has this flag set) and PG_private_2 to
939 * identify the last page.
942 for (i
= 0; i
< class->pages_per_zspage
; i
++) {
945 page
= alloc_page(flags
);
949 INIT_LIST_HEAD(&page
->lru
);
950 if (i
== 0) { /* first page */
951 SetPagePrivate(page
);
952 set_page_private(page
, 0);
954 first_page
->inuse
= 0;
957 set_page_private(first_page
, (unsigned long)page
);
959 page
->first_page
= first_page
;
961 list_add(&page
->lru
, &prev_page
->lru
);
962 if (i
== class->pages_per_zspage
- 1) /* last page */
963 SetPagePrivate2(page
);
967 init_zspage(first_page
, class);
969 first_page
->freelist
= location_to_obj(first_page
, 0);
970 /* Maximum number of objects we can store in this zspage */
971 first_page
->objects
= class->pages_per_zspage
* PAGE_SIZE
/ class->size
;
973 error
= 0; /* Success */
976 if (unlikely(error
) && first_page
) {
977 free_zspage(first_page
);
984 static struct page
*find_get_zspage(struct size_class
*class)
989 for (i
= 0; i
< _ZS_NR_FULLNESS_GROUPS
; i
++) {
990 page
= class->fullness_list
[i
];
998 #ifdef CONFIG_PGTABLE_MAPPING
999 static inline int __zs_cpu_up(struct mapping_area
*area
)
1002 * Make sure we don't leak memory if a cpu UP notification
1003 * and zs_init() race and both call zs_cpu_up() on the same cpu
1007 area
->vm
= alloc_vm_area(PAGE_SIZE
* 2, NULL
);
1013 static inline void __zs_cpu_down(struct mapping_area
*area
)
1016 free_vm_area(area
->vm
);
1020 static inline void *__zs_map_object(struct mapping_area
*area
,
1021 struct page
*pages
[2], int off
, int size
)
1023 BUG_ON(map_vm_area(area
->vm
, PAGE_KERNEL
, pages
));
1024 area
->vm_addr
= area
->vm
->addr
;
1025 return area
->vm_addr
+ off
;
1028 static inline void __zs_unmap_object(struct mapping_area
*area
,
1029 struct page
*pages
[2], int off
, int size
)
1031 unsigned long addr
= (unsigned long)area
->vm_addr
;
1033 unmap_kernel_range(addr
, PAGE_SIZE
* 2);
1036 #else /* CONFIG_PGTABLE_MAPPING */
1038 static inline int __zs_cpu_up(struct mapping_area
*area
)
1041 * Make sure we don't leak memory if a cpu UP notification
1042 * and zs_init() race and both call zs_cpu_up() on the same cpu
1046 area
->vm_buf
= kmalloc(ZS_MAX_ALLOC_SIZE
, GFP_KERNEL
);
1052 static inline void __zs_cpu_down(struct mapping_area
*area
)
1054 kfree(area
->vm_buf
);
1055 area
->vm_buf
= NULL
;
1058 static void *__zs_map_object(struct mapping_area
*area
,
1059 struct page
*pages
[2], int off
, int size
)
1063 char *buf
= area
->vm_buf
;
1065 /* disable page faults to match kmap_atomic() return conditions */
1066 pagefault_disable();
1068 /* no read fastpath */
1069 if (area
->vm_mm
== ZS_MM_WO
)
1072 sizes
[0] = PAGE_SIZE
- off
;
1073 sizes
[1] = size
- sizes
[0];
1075 /* copy object to per-cpu buffer */
1076 addr
= kmap_atomic(pages
[0]);
1077 memcpy(buf
, addr
+ off
, sizes
[0]);
1078 kunmap_atomic(addr
);
1079 addr
= kmap_atomic(pages
[1]);
1080 memcpy(buf
+ sizes
[0], addr
, sizes
[1]);
1081 kunmap_atomic(addr
);
1083 return area
->vm_buf
;
1086 static void __zs_unmap_object(struct mapping_area
*area
,
1087 struct page
*pages
[2], int off
, int size
)
1093 /* no write fastpath */
1094 if (area
->vm_mm
== ZS_MM_RO
)
1099 buf
= buf
+ ZS_HANDLE_SIZE
;
1100 size
-= ZS_HANDLE_SIZE
;
1101 off
+= ZS_HANDLE_SIZE
;
1104 sizes
[0] = PAGE_SIZE
- off
;
1105 sizes
[1] = size
- sizes
[0];
1107 /* copy per-cpu buffer to object */
1108 addr
= kmap_atomic(pages
[0]);
1109 memcpy(addr
+ off
, buf
, sizes
[0]);
1110 kunmap_atomic(addr
);
1111 addr
= kmap_atomic(pages
[1]);
1112 memcpy(addr
, buf
+ sizes
[0], sizes
[1]);
1113 kunmap_atomic(addr
);
1116 /* enable page faults to match kunmap_atomic() return conditions */
1120 #endif /* CONFIG_PGTABLE_MAPPING */
1122 static int zs_cpu_notifier(struct notifier_block
*nb
, unsigned long action
,
1125 int ret
, cpu
= (long)pcpu
;
1126 struct mapping_area
*area
;
1129 case CPU_UP_PREPARE
:
1130 area
= &per_cpu(zs_map_area
, cpu
);
1131 ret
= __zs_cpu_up(area
);
1133 return notifier_from_errno(ret
);
1136 case CPU_UP_CANCELED
:
1137 area
= &per_cpu(zs_map_area
, cpu
);
1138 __zs_cpu_down(area
);
1145 static struct notifier_block zs_cpu_nb
= {
1146 .notifier_call
= zs_cpu_notifier
1149 static int zs_register_cpu_notifier(void)
1151 int cpu
, uninitialized_var(ret
);
1153 cpu_notifier_register_begin();
1155 __register_cpu_notifier(&zs_cpu_nb
);
1156 for_each_online_cpu(cpu
) {
1157 ret
= zs_cpu_notifier(NULL
, CPU_UP_PREPARE
, (void *)(long)cpu
);
1158 if (notifier_to_errno(ret
))
1162 cpu_notifier_register_done();
1163 return notifier_to_errno(ret
);
1166 static void zs_unregister_cpu_notifier(void)
1170 cpu_notifier_register_begin();
1172 for_each_online_cpu(cpu
)
1173 zs_cpu_notifier(NULL
, CPU_DEAD
, (void *)(long)cpu
);
1174 __unregister_cpu_notifier(&zs_cpu_nb
);
1176 cpu_notifier_register_done();
1179 static void init_zs_size_classes(void)
1183 nr
= (ZS_MAX_ALLOC_SIZE
- ZS_MIN_ALLOC_SIZE
) / ZS_SIZE_CLASS_DELTA
+ 1;
1184 if ((ZS_MAX_ALLOC_SIZE
- ZS_MIN_ALLOC_SIZE
) % ZS_SIZE_CLASS_DELTA
)
1187 zs_size_classes
= nr
;
1190 static bool can_merge(struct size_class
*prev
, int size
, int pages_per_zspage
)
1192 if (prev
->pages_per_zspage
!= pages_per_zspage
)
1195 if (get_maxobj_per_zspage(prev
->size
, prev
->pages_per_zspage
)
1196 != get_maxobj_per_zspage(size
, pages_per_zspage
))
1202 static bool zspage_full(struct page
*page
)
1204 BUG_ON(!is_first_page(page
));
1206 return page
->inuse
== page
->objects
;
1209 unsigned long zs_get_total_pages(struct zs_pool
*pool
)
1211 return atomic_long_read(&pool
->pages_allocated
);
1213 EXPORT_SYMBOL_GPL(zs_get_total_pages
);
1216 * zs_map_object - get address of allocated object from handle.
1217 * @pool: pool from which the object was allocated
1218 * @handle: handle returned from zs_malloc
1220 * Before using an object allocated from zs_malloc, it must be mapped using
1221 * this function. When done with the object, it must be unmapped using
1224 * Only one object can be mapped per cpu at a time. There is no protection
1225 * against nested mappings.
1227 * This function returns with preemption and page faults disabled.
1229 void *zs_map_object(struct zs_pool
*pool
, unsigned long handle
,
1233 unsigned long obj
, obj_idx
, off
;
1235 unsigned int class_idx
;
1236 enum fullness_group fg
;
1237 struct size_class
*class;
1238 struct mapping_area
*area
;
1239 struct page
*pages
[2];
1245 * Because we use per-cpu mapping areas shared among the
1246 * pools/users, we can't allow mapping in interrupt context
1247 * because it can corrupt another users mappings.
1249 BUG_ON(in_interrupt());
1251 /* From now on, migration cannot move the object */
1254 obj
= handle_to_obj(handle
);
1255 obj_to_location(obj
, &page
, &obj_idx
);
1256 get_zspage_mapping(get_first_page(page
), &class_idx
, &fg
);
1257 class = pool
->size_class
[class_idx
];
1258 off
= obj_idx_to_offset(page
, obj_idx
, class->size
);
1260 area
= &get_cpu_var(zs_map_area
);
1262 if (off
+ class->size
<= PAGE_SIZE
) {
1263 /* this object is contained entirely within a page */
1264 area
->vm_addr
= kmap_atomic(page
);
1265 ret
= area
->vm_addr
+ off
;
1269 /* this object spans two pages */
1271 pages
[1] = get_next_page(page
);
1274 ret
= __zs_map_object(area
, pages
, off
, class->size
);
1277 ret
+= ZS_HANDLE_SIZE
;
1281 EXPORT_SYMBOL_GPL(zs_map_object
);
1283 void zs_unmap_object(struct zs_pool
*pool
, unsigned long handle
)
1286 unsigned long obj
, obj_idx
, off
;
1288 unsigned int class_idx
;
1289 enum fullness_group fg
;
1290 struct size_class
*class;
1291 struct mapping_area
*area
;
1295 obj
= handle_to_obj(handle
);
1296 obj_to_location(obj
, &page
, &obj_idx
);
1297 get_zspage_mapping(get_first_page(page
), &class_idx
, &fg
);
1298 class = pool
->size_class
[class_idx
];
1299 off
= obj_idx_to_offset(page
, obj_idx
, class->size
);
1301 area
= this_cpu_ptr(&zs_map_area
);
1302 if (off
+ class->size
<= PAGE_SIZE
)
1303 kunmap_atomic(area
->vm_addr
);
1305 struct page
*pages
[2];
1308 pages
[1] = get_next_page(page
);
1311 __zs_unmap_object(area
, pages
, off
, class->size
);
1313 put_cpu_var(zs_map_area
);
1316 EXPORT_SYMBOL_GPL(zs_unmap_object
);
1318 static unsigned long obj_malloc(struct page
*first_page
,
1319 struct size_class
*class, unsigned long handle
)
1322 struct link_free
*link
;
1324 struct page
*m_page
;
1325 unsigned long m_objidx
, m_offset
;
1328 handle
|= OBJ_ALLOCATED_TAG
;
1329 obj
= (unsigned long)first_page
->freelist
;
1330 obj_to_location(obj
, &m_page
, &m_objidx
);
1331 m_offset
= obj_idx_to_offset(m_page
, m_objidx
, class->size
);
1333 vaddr
= kmap_atomic(m_page
);
1334 link
= (struct link_free
*)vaddr
+ m_offset
/ sizeof(*link
);
1335 first_page
->freelist
= link
->next
;
1337 /* record handle in the header of allocated chunk */
1338 link
->handle
= handle
;
1340 /* record handle in first_page->private */
1341 set_page_private(first_page
, handle
);
1342 kunmap_atomic(vaddr
);
1343 first_page
->inuse
++;
1344 zs_stat_inc(class, OBJ_USED
, 1);
1351 * zs_malloc - Allocate block of given size from pool.
1352 * @pool: pool to allocate from
1353 * @size: size of block to allocate
1355 * On success, handle to the allocated object is returned,
1357 * Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
1359 unsigned long zs_malloc(struct zs_pool
*pool
, size_t size
)
1361 unsigned long handle
, obj
;
1362 struct size_class
*class;
1363 struct page
*first_page
;
1365 if (unlikely(!size
|| size
> ZS_MAX_ALLOC_SIZE
))
1368 handle
= alloc_handle(pool
);
1372 /* extra space in chunk to keep the handle */
1373 size
+= ZS_HANDLE_SIZE
;
1374 class = pool
->size_class
[get_size_class_index(size
)];
1376 spin_lock(&class->lock
);
1377 first_page
= find_get_zspage(class);
1380 spin_unlock(&class->lock
);
1381 first_page
= alloc_zspage(class, pool
->flags
);
1382 if (unlikely(!first_page
)) {
1383 free_handle(pool
, handle
);
1387 set_zspage_mapping(first_page
, class->index
, ZS_EMPTY
);
1388 atomic_long_add(class->pages_per_zspage
,
1389 &pool
->pages_allocated
);
1391 spin_lock(&class->lock
);
1392 zs_stat_inc(class, OBJ_ALLOCATED
, get_maxobj_per_zspage(
1393 class->size
, class->pages_per_zspage
));
1396 obj
= obj_malloc(first_page
, class, handle
);
1397 /* Now move the zspage to another fullness group, if required */
1398 fix_fullness_group(class, first_page
);
1399 record_obj(handle
, obj
);
1400 spin_unlock(&class->lock
);
1404 EXPORT_SYMBOL_GPL(zs_malloc
);
1406 static void obj_free(struct zs_pool
*pool
, struct size_class
*class,
1409 struct link_free
*link
;
1410 struct page
*first_page
, *f_page
;
1411 unsigned long f_objidx
, f_offset
;
1414 enum fullness_group fullness
;
1418 obj
&= ~OBJ_ALLOCATED_TAG
;
1419 obj_to_location(obj
, &f_page
, &f_objidx
);
1420 first_page
= get_first_page(f_page
);
1422 get_zspage_mapping(first_page
, &class_idx
, &fullness
);
1423 f_offset
= obj_idx_to_offset(f_page
, f_objidx
, class->size
);
1425 vaddr
= kmap_atomic(f_page
);
1427 /* Insert this object in containing zspage's freelist */
1428 link
= (struct link_free
*)(vaddr
+ f_offset
);
1429 link
->next
= first_page
->freelist
;
1431 set_page_private(first_page
, 0);
1432 kunmap_atomic(vaddr
);
1433 first_page
->freelist
= (void *)obj
;
1434 first_page
->inuse
--;
1435 zs_stat_dec(class, OBJ_USED
, 1);
1438 void zs_free(struct zs_pool
*pool
, unsigned long handle
)
1440 struct page
*first_page
, *f_page
;
1441 unsigned long obj
, f_objidx
;
1443 struct size_class
*class;
1444 enum fullness_group fullness
;
1446 if (unlikely(!handle
))
1450 obj
= handle_to_obj(handle
);
1451 obj_to_location(obj
, &f_page
, &f_objidx
);
1452 first_page
= get_first_page(f_page
);
1454 get_zspage_mapping(first_page
, &class_idx
, &fullness
);
1455 class = pool
->size_class
[class_idx
];
1457 spin_lock(&class->lock
);
1458 obj_free(pool
, class, obj
);
1459 fullness
= fix_fullness_group(class, first_page
);
1460 if (fullness
== ZS_EMPTY
) {
1461 zs_stat_dec(class, OBJ_ALLOCATED
, get_maxobj_per_zspage(
1462 class->size
, class->pages_per_zspage
));
1463 atomic_long_sub(class->pages_per_zspage
,
1464 &pool
->pages_allocated
);
1465 free_zspage(first_page
);
1467 spin_unlock(&class->lock
);
1470 free_handle(pool
, handle
);
1472 EXPORT_SYMBOL_GPL(zs_free
);
1474 static void zs_object_copy(unsigned long dst
, unsigned long src
,
1475 struct size_class
*class)
1477 struct page
*s_page
, *d_page
;
1478 unsigned long s_objidx
, d_objidx
;
1479 unsigned long s_off
, d_off
;
1480 void *s_addr
, *d_addr
;
1481 int s_size
, d_size
, size
;
1484 s_size
= d_size
= class->size
;
1486 obj_to_location(src
, &s_page
, &s_objidx
);
1487 obj_to_location(dst
, &d_page
, &d_objidx
);
1489 s_off
= obj_idx_to_offset(s_page
, s_objidx
, class->size
);
1490 d_off
= obj_idx_to_offset(d_page
, d_objidx
, class->size
);
1492 if (s_off
+ class->size
> PAGE_SIZE
)
1493 s_size
= PAGE_SIZE
- s_off
;
1495 if (d_off
+ class->size
> PAGE_SIZE
)
1496 d_size
= PAGE_SIZE
- d_off
;
1498 s_addr
= kmap_atomic(s_page
);
1499 d_addr
= kmap_atomic(d_page
);
1502 size
= min(s_size
, d_size
);
1503 memcpy(d_addr
+ d_off
, s_addr
+ s_off
, size
);
1506 if (written
== class->size
)
1514 if (s_off
>= PAGE_SIZE
) {
1515 kunmap_atomic(d_addr
);
1516 kunmap_atomic(s_addr
);
1517 s_page
= get_next_page(s_page
);
1519 s_addr
= kmap_atomic(s_page
);
1520 d_addr
= kmap_atomic(d_page
);
1521 s_size
= class->size
- written
;
1525 if (d_off
>= PAGE_SIZE
) {
1526 kunmap_atomic(d_addr
);
1527 d_page
= get_next_page(d_page
);
1529 d_addr
= kmap_atomic(d_page
);
1530 d_size
= class->size
- written
;
1535 kunmap_atomic(d_addr
);
1536 kunmap_atomic(s_addr
);
1540 * Find alloced object in zspage from index object and
1543 static unsigned long find_alloced_obj(struct page
*page
, int index
,
1544 struct size_class
*class)
1548 unsigned long handle
= 0;
1549 void *addr
= kmap_atomic(page
);
1551 if (!is_first_page(page
))
1552 offset
= page
->index
;
1553 offset
+= class->size
* index
;
1555 while (offset
< PAGE_SIZE
) {
1556 head
= obj_to_head(class, page
, addr
+ offset
);
1557 if (head
& OBJ_ALLOCATED_TAG
) {
1558 handle
= head
& ~OBJ_ALLOCATED_TAG
;
1559 if (trypin_tag(handle
))
1564 offset
+= class->size
;
1568 kunmap_atomic(addr
);
1572 struct zs_compact_control
{
1573 /* Source page for migration which could be a subpage of zspage. */
1574 struct page
*s_page
;
1575 /* Destination page for migration which should be a first page
1577 struct page
*d_page
;
1578 /* Starting object index within @s_page which used for live object
1579 * in the subpage. */
1581 /* how many of objects are migrated */
1585 static int migrate_zspage(struct zs_pool
*pool
, struct size_class
*class,
1586 struct zs_compact_control
*cc
)
1588 unsigned long used_obj
, free_obj
;
1589 unsigned long handle
;
1590 struct page
*s_page
= cc
->s_page
;
1591 struct page
*d_page
= cc
->d_page
;
1592 unsigned long index
= cc
->index
;
1593 int nr_migrated
= 0;
1597 handle
= find_alloced_obj(s_page
, index
, class);
1599 s_page
= get_next_page(s_page
);
1606 /* Stop if there is no more space */
1607 if (zspage_full(d_page
)) {
1613 used_obj
= handle_to_obj(handle
);
1614 free_obj
= obj_malloc(d_page
, class, handle
);
1615 zs_object_copy(free_obj
, used_obj
, class);
1617 record_obj(handle
, free_obj
);
1619 obj_free(pool
, class, used_obj
);
1623 /* Remember last position in this iteration */
1624 cc
->s_page
= s_page
;
1626 cc
->nr_migrated
= nr_migrated
;
1631 static struct page
*isolate_target_page(struct size_class
*class)
1636 for (i
= 0; i
< _ZS_NR_FULLNESS_GROUPS
; i
++) {
1637 page
= class->fullness_list
[i
];
1639 remove_zspage(page
, class, i
);
1647 static void putback_zspage(struct zs_pool
*pool
, struct size_class
*class,
1648 struct page
*first_page
)
1650 enum fullness_group fullness
;
1652 BUG_ON(!is_first_page(first_page
));
1654 fullness
= get_fullness_group(first_page
);
1655 insert_zspage(first_page
, class, fullness
);
1656 set_zspage_mapping(first_page
, class->index
, fullness
);
1658 if (fullness
== ZS_EMPTY
) {
1659 zs_stat_dec(class, OBJ_ALLOCATED
, get_maxobj_per_zspage(
1660 class->size
, class->pages_per_zspage
));
1661 atomic_long_sub(class->pages_per_zspage
,
1662 &pool
->pages_allocated
);
1664 free_zspage(first_page
);
1668 static struct page
*isolate_source_page(struct size_class
*class)
1672 page
= class->fullness_list
[ZS_ALMOST_EMPTY
];
1674 remove_zspage(page
, class, ZS_ALMOST_EMPTY
);
1681 * Based on the number of unused allocated objects calculate
1682 * and return the number of pages that we can free.
1684 * Should be called under class->lock.
1686 static unsigned long zs_can_compact(struct size_class
*class)
1688 unsigned long obj_wasted
;
1690 if (!zs_stat_get(class, CLASS_ALMOST_EMPTY
))
1693 obj_wasted
= zs_stat_get(class, OBJ_ALLOCATED
) -
1694 zs_stat_get(class, OBJ_USED
);
1696 obj_wasted
/= get_maxobj_per_zspage(class->size
,
1697 class->pages_per_zspage
);
1699 return obj_wasted
* get_pages_per_zspage(class->size
);
1702 static unsigned long __zs_compact(struct zs_pool
*pool
,
1703 struct size_class
*class)
1705 struct zs_compact_control cc
;
1706 struct page
*src_page
;
1707 struct page
*dst_page
= NULL
;
1708 unsigned long nr_total_migrated
= 0;
1710 spin_lock(&class->lock
);
1711 while ((src_page
= isolate_source_page(class))) {
1713 BUG_ON(!is_first_page(src_page
));
1715 if (!zs_can_compact(class))
1719 cc
.s_page
= src_page
;
1721 while ((dst_page
= isolate_target_page(class))) {
1722 cc
.d_page
= dst_page
;
1724 * If there is no more space in dst_page, resched
1725 * and see if anyone had allocated another zspage.
1727 if (!migrate_zspage(pool
, class, &cc
))
1730 putback_zspage(pool
, class, dst_page
);
1731 nr_total_migrated
+= cc
.nr_migrated
;
1734 /* Stop if we couldn't find slot */
1735 if (dst_page
== NULL
)
1738 putback_zspage(pool
, class, dst_page
);
1739 putback_zspage(pool
, class, src_page
);
1740 spin_unlock(&class->lock
);
1741 nr_total_migrated
+= cc
.nr_migrated
;
1743 spin_lock(&class->lock
);
1747 putback_zspage(pool
, class, src_page
);
1749 spin_unlock(&class->lock
);
1751 return nr_total_migrated
;
1754 unsigned long zs_compact(struct zs_pool
*pool
)
1757 unsigned long nr_migrated
= 0;
1758 struct size_class
*class;
1760 for (i
= zs_size_classes
- 1; i
>= 0; i
--) {
1761 class = pool
->size_class
[i
];
1764 if (class->index
!= i
)
1766 nr_migrated
+= __zs_compact(pool
, class);
1771 EXPORT_SYMBOL_GPL(zs_compact
);
1774 * zs_create_pool - Creates an allocation pool to work from.
1775 * @flags: allocation flags used to allocate pool metadata
1777 * This function must be called before anything when using
1778 * the zsmalloc allocator.
1780 * On success, a pointer to the newly created pool is returned,
1783 struct zs_pool
*zs_create_pool(char *name
, gfp_t flags
)
1786 struct zs_pool
*pool
;
1787 struct size_class
*prev_class
= NULL
;
1789 pool
= kzalloc(sizeof(*pool
), GFP_KERNEL
);
1793 pool
->size_class
= kcalloc(zs_size_classes
, sizeof(struct size_class
*),
1795 if (!pool
->size_class
) {
1800 pool
->name
= kstrdup(name
, GFP_KERNEL
);
1804 if (create_handle_cache(pool
))
1808 * Iterate reversly, because, size of size_class that we want to use
1809 * for merging should be larger or equal to current size.
1811 for (i
= zs_size_classes
- 1; i
>= 0; i
--) {
1813 int pages_per_zspage
;
1814 struct size_class
*class;
1816 size
= ZS_MIN_ALLOC_SIZE
+ i
* ZS_SIZE_CLASS_DELTA
;
1817 if (size
> ZS_MAX_ALLOC_SIZE
)
1818 size
= ZS_MAX_ALLOC_SIZE
;
1819 pages_per_zspage
= get_pages_per_zspage(size
);
1822 * size_class is used for normal zsmalloc operation such
1823 * as alloc/free for that size. Although it is natural that we
1824 * have one size_class for each size, there is a chance that we
1825 * can get more memory utilization if we use one size_class for
1826 * many different sizes whose size_class have same
1827 * characteristics. So, we makes size_class point to
1828 * previous size_class if possible.
1831 if (can_merge(prev_class
, size
, pages_per_zspage
)) {
1832 pool
->size_class
[i
] = prev_class
;
1837 class = kzalloc(sizeof(struct size_class
), GFP_KERNEL
);
1843 class->pages_per_zspage
= pages_per_zspage
;
1844 if (pages_per_zspage
== 1 &&
1845 get_maxobj_per_zspage(size
, pages_per_zspage
) == 1)
1847 spin_lock_init(&class->lock
);
1848 pool
->size_class
[i
] = class;
1853 pool
->flags
= flags
;
1855 if (zs_pool_stat_create(name
, pool
))
1861 zs_destroy_pool(pool
);
1864 EXPORT_SYMBOL_GPL(zs_create_pool
);
1866 void zs_destroy_pool(struct zs_pool
*pool
)
1870 zs_pool_stat_destroy(pool
);
1872 for (i
= 0; i
< zs_size_classes
; i
++) {
1874 struct size_class
*class = pool
->size_class
[i
];
1879 if (class->index
!= i
)
1882 for (fg
= 0; fg
< _ZS_NR_FULLNESS_GROUPS
; fg
++) {
1883 if (class->fullness_list
[fg
]) {
1884 pr_info("Freeing non-empty class with size %db, fullness group %d\n",
1891 destroy_handle_cache(pool
);
1892 kfree(pool
->size_class
);
1896 EXPORT_SYMBOL_GPL(zs_destroy_pool
);
1898 static int __init
zs_init(void)
1900 int ret
= zs_register_cpu_notifier();
1905 init_zs_size_classes();
1908 zpool_register_driver(&zs_zpool_driver
);
1911 ret
= zs_stat_init();
1913 pr_err("zs stat initialization failed\n");
1920 zpool_unregister_driver(&zs_zpool_driver
);
1923 zs_unregister_cpu_notifier();
1928 static void __exit
zs_exit(void)
1931 zpool_unregister_driver(&zs_zpool_driver
);
1933 zs_unregister_cpu_notifier();
1938 module_init(zs_init
);
1939 module_exit(zs_exit
);
1941 MODULE_LICENSE("Dual BSD/GPL");
1942 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");