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->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
23 * page->units: first object offset in a subpage of zspage
25 * Usage of struct page flags:
26 * PG_private: identifies the first component page
27 * PG_owner_priv_1: identifies the huge component page
31 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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/pseudo_fs.h>
56 #include <linux/migrate.h>
57 #include <linux/pagemap.h>
60 #define ZSPAGE_MAGIC 0x58
63 * This must be power of 2 and greater than of equal to sizeof(link_free).
64 * These two conditions ensure that any 'struct link_free' itself doesn't
65 * span more than 1 page which avoids complex case of mapping 2 pages simply
66 * to restore link_free pointer values.
71 * A single 'zspage' is composed of up to 2^N discontiguous 0-order (single)
72 * pages. ZS_MAX_ZSPAGE_ORDER defines upper limit on N.
74 #define ZS_MAX_ZSPAGE_ORDER 2
75 #define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER)
77 #define ZS_HANDLE_SIZE (sizeof(unsigned long))
80 * Object location (<PFN>, <obj_idx>) is encoded as
81 * as single (unsigned long) handle value.
83 * Note that object index <obj_idx> starts from 0.
85 * This is made more complicated by various memory models and PAE.
88 #ifndef MAX_POSSIBLE_PHYSMEM_BITS
89 #ifdef MAX_PHYSMEM_BITS
90 #define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS
93 * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just
96 #define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG
100 #define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT)
103 * Memory for allocating for handle keeps object position by
104 * encoding <page, obj_idx> and the encoded value has a room
105 * in least bit(ie, look at obj_to_location).
106 * We use the bit to synchronize between object access by
107 * user and migration.
109 #define HANDLE_PIN_BIT 0
112 * Head in allocated object should have OBJ_ALLOCATED_TAG
113 * to identify the object was allocated or not.
114 * It's okay to add the status bit in the least bit because
115 * header keeps handle which is 4byte-aligned address so we
116 * have room for two bit at least.
118 #define OBJ_ALLOCATED_TAG 1
119 #define OBJ_TAG_BITS 1
120 #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
121 #define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
123 #define FULLNESS_BITS 2
125 #define ISOLATED_BITS 3
126 #define MAGIC_VAL_BITS 8
128 #define MAX(a, b) ((a) >= (b) ? (a) : (b))
129 /* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
130 #define ZS_MIN_ALLOC_SIZE \
131 MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
132 /* each chunk includes extra space to keep handle */
133 #define ZS_MAX_ALLOC_SIZE PAGE_SIZE
136 * On systems with 4K page size, this gives 255 size classes! There is a
138 * - Large number of size classes is potentially wasteful as free page are
139 * spread across these classes
140 * - Small number of size classes causes large internal fragmentation
141 * - Probably its better to use specific size classes (empirically
142 * determined). NOTE: all those class sizes must be set as multiple of
143 * ZS_ALIGN to make sure link_free itself never has to span 2 pages.
145 * ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN
148 #define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> CLASS_BITS)
149 #define ZS_SIZE_CLASSES (DIV_ROUND_UP(ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE, \
150 ZS_SIZE_CLASS_DELTA) + 1)
152 enum fullness_group
{
170 struct zs_size_stat
{
171 unsigned long objs
[NR_ZS_STAT_TYPE
];
174 #ifdef CONFIG_ZSMALLOC_STAT
175 static struct dentry
*zs_stat_root
;
178 #ifdef CONFIG_COMPACTION
179 static struct vfsmount
*zsmalloc_mnt
;
183 * We assign a page to ZS_ALMOST_EMPTY fullness group when:
185 * n = number of allocated objects
186 * N = total number of objects zspage can store
187 * f = fullness_threshold_frac
189 * Similarly, we assign zspage to:
190 * ZS_ALMOST_FULL when n > N / f
191 * ZS_EMPTY when n == 0
192 * ZS_FULL when n == N
194 * (see: fix_fullness_group())
196 static const int fullness_threshold_frac
= 4;
197 static size_t huge_class_size
;
201 struct list_head fullness_list
[NR_ZS_FULLNESS
];
203 * Size of objects stored in this class. Must be multiple
208 /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
209 int pages_per_zspage
;
212 struct zs_size_stat stats
;
215 /* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
216 static void SetPageHugeObject(struct page
*page
)
218 SetPageOwnerPriv1(page
);
221 static void ClearPageHugeObject(struct page
*page
)
223 ClearPageOwnerPriv1(page
);
226 static int PageHugeObject(struct page
*page
)
228 return PageOwnerPriv1(page
);
232 * Placed within free objects to form a singly linked list.
233 * For every zspage, zspage->freeobj gives head of this list.
235 * This must be power of 2 and less than or equal to ZS_ALIGN
241 * It's valid for non-allocated object
245 * Handle of allocated object.
247 unsigned long handle
;
254 struct size_class
*size_class
[ZS_SIZE_CLASSES
];
255 struct kmem_cache
*handle_cachep
;
256 struct kmem_cache
*zspage_cachep
;
258 atomic_long_t pages_allocated
;
260 struct zs_pool_stats stats
;
262 /* Compact classes */
263 struct shrinker shrinker
;
265 #ifdef CONFIG_ZSMALLOC_STAT
266 struct dentry
*stat_dentry
;
268 #ifdef CONFIG_COMPACTION
270 struct work_struct free_work
;
276 unsigned int fullness
:FULLNESS_BITS
;
277 unsigned int class:CLASS_BITS
+ 1;
278 unsigned int isolated
:ISOLATED_BITS
;
279 unsigned int magic
:MAGIC_VAL_BITS
;
282 unsigned int freeobj
;
283 struct page
*first_page
;
284 struct list_head list
; /* fullness list */
285 #ifdef CONFIG_COMPACTION
290 struct mapping_area
{
291 #ifdef CONFIG_PGTABLE_MAPPING
292 struct vm_struct
*vm
; /* vm area for mapping object that span pages */
294 char *vm_buf
; /* copy buffer for objects that span pages */
296 char *vm_addr
; /* address of kmap_atomic()'ed pages */
297 enum zs_mapmode vm_mm
; /* mapping mode */
300 #ifdef CONFIG_COMPACTION
301 static int zs_register_migration(struct zs_pool
*pool
);
302 static void zs_unregister_migration(struct zs_pool
*pool
);
303 static void migrate_lock_init(struct zspage
*zspage
);
304 static void migrate_read_lock(struct zspage
*zspage
);
305 static void migrate_read_unlock(struct zspage
*zspage
);
306 static void kick_deferred_free(struct zs_pool
*pool
);
307 static void init_deferred_free(struct zs_pool
*pool
);
308 static void SetZsPageMovable(struct zs_pool
*pool
, struct zspage
*zspage
);
310 static int zsmalloc_mount(void) { return 0; }
311 static void zsmalloc_unmount(void) {}
312 static int zs_register_migration(struct zs_pool
*pool
) { return 0; }
313 static void zs_unregister_migration(struct zs_pool
*pool
) {}
314 static void migrate_lock_init(struct zspage
*zspage
) {}
315 static void migrate_read_lock(struct zspage
*zspage
) {}
316 static void migrate_read_unlock(struct zspage
*zspage
) {}
317 static void kick_deferred_free(struct zs_pool
*pool
) {}
318 static void init_deferred_free(struct zs_pool
*pool
) {}
319 static void SetZsPageMovable(struct zs_pool
*pool
, struct zspage
*zspage
) {}
322 static int create_cache(struct zs_pool
*pool
)
324 pool
->handle_cachep
= kmem_cache_create("zs_handle", ZS_HANDLE_SIZE
,
326 if (!pool
->handle_cachep
)
329 pool
->zspage_cachep
= kmem_cache_create("zspage", sizeof(struct zspage
),
331 if (!pool
->zspage_cachep
) {
332 kmem_cache_destroy(pool
->handle_cachep
);
333 pool
->handle_cachep
= NULL
;
340 static void destroy_cache(struct zs_pool
*pool
)
342 kmem_cache_destroy(pool
->handle_cachep
);
343 kmem_cache_destroy(pool
->zspage_cachep
);
346 static unsigned long cache_alloc_handle(struct zs_pool
*pool
, gfp_t gfp
)
348 return (unsigned long)kmem_cache_alloc(pool
->handle_cachep
,
349 gfp
& ~(__GFP_HIGHMEM
|__GFP_MOVABLE
));
352 static void cache_free_handle(struct zs_pool
*pool
, unsigned long handle
)
354 kmem_cache_free(pool
->handle_cachep
, (void *)handle
);
357 static struct zspage
*cache_alloc_zspage(struct zs_pool
*pool
, gfp_t flags
)
359 return kmem_cache_alloc(pool
->zspage_cachep
,
360 flags
& ~(__GFP_HIGHMEM
|__GFP_MOVABLE
));
363 static void cache_free_zspage(struct zs_pool
*pool
, struct zspage
*zspage
)
365 kmem_cache_free(pool
->zspage_cachep
, zspage
);
368 static void record_obj(unsigned long handle
, unsigned long obj
)
371 * lsb of @obj represents handle lock while other bits
372 * represent object value the handle is pointing so
373 * updating shouldn't do store tearing.
375 WRITE_ONCE(*(unsigned long *)handle
, obj
);
382 static void *zs_zpool_create(const char *name
, gfp_t gfp
,
383 const struct zpool_ops
*zpool_ops
,
387 * Ignore global gfp flags: zs_malloc() may be invoked from
388 * different contexts and its caller must provide a valid
391 return zs_create_pool(name
);
394 static void zs_zpool_destroy(void *pool
)
396 zs_destroy_pool(pool
);
399 static int zs_zpool_malloc(void *pool
, size_t size
, gfp_t gfp
,
400 unsigned long *handle
)
402 *handle
= zs_malloc(pool
, size
, gfp
);
403 return *handle
? 0 : -1;
405 static void zs_zpool_free(void *pool
, unsigned long handle
)
407 zs_free(pool
, handle
);
410 static void *zs_zpool_map(void *pool
, unsigned long handle
,
411 enum zpool_mapmode mm
)
413 enum zs_mapmode zs_mm
;
422 case ZPOOL_MM_RW
: /* fall through */
428 return zs_map_object(pool
, handle
, zs_mm
);
430 static void zs_zpool_unmap(void *pool
, unsigned long handle
)
432 zs_unmap_object(pool
, handle
);
435 static u64
zs_zpool_total_size(void *pool
)
437 return zs_get_total_pages(pool
) << PAGE_SHIFT
;
440 static struct zpool_driver zs_zpool_driver
= {
442 .owner
= THIS_MODULE
,
443 .create
= zs_zpool_create
,
444 .destroy
= zs_zpool_destroy
,
445 .malloc
= zs_zpool_malloc
,
446 .free
= zs_zpool_free
,
448 .unmap
= zs_zpool_unmap
,
449 .total_size
= zs_zpool_total_size
,
452 MODULE_ALIAS("zpool-zsmalloc");
453 #endif /* CONFIG_ZPOOL */
455 /* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
456 static DEFINE_PER_CPU(struct mapping_area
, zs_map_area
);
458 static bool is_zspage_isolated(struct zspage
*zspage
)
460 return zspage
->isolated
;
463 static __maybe_unused
int is_first_page(struct page
*page
)
465 return PagePrivate(page
);
468 /* Protected by class->lock */
469 static inline int get_zspage_inuse(struct zspage
*zspage
)
471 return zspage
->inuse
;
474 static inline void set_zspage_inuse(struct zspage
*zspage
, int val
)
479 static inline void mod_zspage_inuse(struct zspage
*zspage
, int val
)
481 zspage
->inuse
+= val
;
484 static inline struct page
*get_first_page(struct zspage
*zspage
)
486 struct page
*first_page
= zspage
->first_page
;
488 VM_BUG_ON_PAGE(!is_first_page(first_page
), first_page
);
492 static inline int get_first_obj_offset(struct page
*page
)
497 static inline void set_first_obj_offset(struct page
*page
, int offset
)
499 page
->units
= offset
;
502 static inline unsigned int get_freeobj(struct zspage
*zspage
)
504 return zspage
->freeobj
;
507 static inline void set_freeobj(struct zspage
*zspage
, unsigned int obj
)
509 zspage
->freeobj
= obj
;
512 static void get_zspage_mapping(struct zspage
*zspage
,
513 unsigned int *class_idx
,
514 enum fullness_group
*fullness
)
516 BUG_ON(zspage
->magic
!= ZSPAGE_MAGIC
);
518 *fullness
= zspage
->fullness
;
519 *class_idx
= zspage
->class;
522 static void set_zspage_mapping(struct zspage
*zspage
,
523 unsigned int class_idx
,
524 enum fullness_group fullness
)
526 zspage
->class = class_idx
;
527 zspage
->fullness
= fullness
;
531 * zsmalloc divides the pool into various size classes where each
532 * class maintains a list of zspages where each zspage is divided
533 * into equal sized chunks. Each allocation falls into one of these
534 * classes depending on its size. This function returns index of the
535 * size class which has chunk size big enough to hold the give size.
537 static int get_size_class_index(int size
)
541 if (likely(size
> ZS_MIN_ALLOC_SIZE
))
542 idx
= DIV_ROUND_UP(size
- ZS_MIN_ALLOC_SIZE
,
543 ZS_SIZE_CLASS_DELTA
);
545 return min_t(int, ZS_SIZE_CLASSES
- 1, idx
);
548 /* type can be of enum type zs_stat_type or fullness_group */
549 static inline void zs_stat_inc(struct size_class
*class,
550 int type
, unsigned long cnt
)
552 class->stats
.objs
[type
] += cnt
;
555 /* type can be of enum type zs_stat_type or fullness_group */
556 static inline void zs_stat_dec(struct size_class
*class,
557 int type
, unsigned long cnt
)
559 class->stats
.objs
[type
] -= cnt
;
562 /* type can be of enum type zs_stat_type or fullness_group */
563 static inline unsigned long zs_stat_get(struct size_class
*class,
566 return class->stats
.objs
[type
];
569 #ifdef CONFIG_ZSMALLOC_STAT
571 static void __init
zs_stat_init(void)
573 if (!debugfs_initialized()) {
574 pr_warn("debugfs not available, stat dir not created\n");
578 zs_stat_root
= debugfs_create_dir("zsmalloc", NULL
);
581 static void __exit
zs_stat_exit(void)
583 debugfs_remove_recursive(zs_stat_root
);
586 static unsigned long zs_can_compact(struct size_class
*class);
588 static int zs_stats_size_show(struct seq_file
*s
, void *v
)
591 struct zs_pool
*pool
= s
->private;
592 struct size_class
*class;
594 unsigned long class_almost_full
, class_almost_empty
;
595 unsigned long obj_allocated
, obj_used
, pages_used
, freeable
;
596 unsigned long total_class_almost_full
= 0, total_class_almost_empty
= 0;
597 unsigned long total_objs
= 0, total_used_objs
= 0, total_pages
= 0;
598 unsigned long total_freeable
= 0;
600 seq_printf(s
, " %5s %5s %11s %12s %13s %10s %10s %16s %8s\n",
601 "class", "size", "almost_full", "almost_empty",
602 "obj_allocated", "obj_used", "pages_used",
603 "pages_per_zspage", "freeable");
605 for (i
= 0; i
< ZS_SIZE_CLASSES
; i
++) {
606 class = pool
->size_class
[i
];
608 if (class->index
!= i
)
611 spin_lock(&class->lock
);
612 class_almost_full
= zs_stat_get(class, CLASS_ALMOST_FULL
);
613 class_almost_empty
= zs_stat_get(class, CLASS_ALMOST_EMPTY
);
614 obj_allocated
= zs_stat_get(class, OBJ_ALLOCATED
);
615 obj_used
= zs_stat_get(class, OBJ_USED
);
616 freeable
= zs_can_compact(class);
617 spin_unlock(&class->lock
);
619 objs_per_zspage
= class->objs_per_zspage
;
620 pages_used
= obj_allocated
/ objs_per_zspage
*
621 class->pages_per_zspage
;
623 seq_printf(s
, " %5u %5u %11lu %12lu %13lu"
624 " %10lu %10lu %16d %8lu\n",
625 i
, class->size
, class_almost_full
, class_almost_empty
,
626 obj_allocated
, obj_used
, pages_used
,
627 class->pages_per_zspage
, freeable
);
629 total_class_almost_full
+= class_almost_full
;
630 total_class_almost_empty
+= class_almost_empty
;
631 total_objs
+= obj_allocated
;
632 total_used_objs
+= obj_used
;
633 total_pages
+= pages_used
;
634 total_freeable
+= freeable
;
638 seq_printf(s
, " %5s %5s %11lu %12lu %13lu %10lu %10lu %16s %8lu\n",
639 "Total", "", total_class_almost_full
,
640 total_class_almost_empty
, total_objs
,
641 total_used_objs
, total_pages
, "", total_freeable
);
645 DEFINE_SHOW_ATTRIBUTE(zs_stats_size
);
647 static void zs_pool_stat_create(struct zs_pool
*pool
, const char *name
)
650 pr_warn("no root stat dir, not creating <%s> stat dir\n", name
);
654 pool
->stat_dentry
= debugfs_create_dir(name
, zs_stat_root
);
656 debugfs_create_file("classes", S_IFREG
| 0444, pool
->stat_dentry
, pool
,
657 &zs_stats_size_fops
);
660 static void zs_pool_stat_destroy(struct zs_pool
*pool
)
662 debugfs_remove_recursive(pool
->stat_dentry
);
665 #else /* CONFIG_ZSMALLOC_STAT */
666 static void __init
zs_stat_init(void)
670 static void __exit
zs_stat_exit(void)
674 static inline void zs_pool_stat_create(struct zs_pool
*pool
, const char *name
)
678 static inline void zs_pool_stat_destroy(struct zs_pool
*pool
)
685 * For each size class, zspages are divided into different groups
686 * depending on how "full" they are. This was done so that we could
687 * easily find empty or nearly empty zspages when we try to shrink
688 * the pool (not yet implemented). This function returns fullness
689 * status of the given page.
691 static enum fullness_group
get_fullness_group(struct size_class
*class,
692 struct zspage
*zspage
)
694 int inuse
, objs_per_zspage
;
695 enum fullness_group fg
;
697 inuse
= get_zspage_inuse(zspage
);
698 objs_per_zspage
= class->objs_per_zspage
;
702 else if (inuse
== objs_per_zspage
)
704 else if (inuse
<= 3 * objs_per_zspage
/ fullness_threshold_frac
)
705 fg
= ZS_ALMOST_EMPTY
;
713 * Each size class maintains various freelists and zspages are assigned
714 * to one of these freelists based on the number of live objects they
715 * have. This functions inserts the given zspage into the freelist
716 * identified by <class, fullness_group>.
718 static void insert_zspage(struct size_class
*class,
719 struct zspage
*zspage
,
720 enum fullness_group fullness
)
724 zs_stat_inc(class, fullness
, 1);
725 head
= list_first_entry_or_null(&class->fullness_list
[fullness
],
726 struct zspage
, list
);
728 * We want to see more ZS_FULL pages and less almost empty/full.
729 * Put pages with higher ->inuse first.
732 if (get_zspage_inuse(zspage
) < get_zspage_inuse(head
)) {
733 list_add(&zspage
->list
, &head
->list
);
737 list_add(&zspage
->list
, &class->fullness_list
[fullness
]);
741 * This function removes the given zspage from the freelist identified
742 * by <class, fullness_group>.
744 static void remove_zspage(struct size_class
*class,
745 struct zspage
*zspage
,
746 enum fullness_group fullness
)
748 VM_BUG_ON(list_empty(&class->fullness_list
[fullness
]));
749 VM_BUG_ON(is_zspage_isolated(zspage
));
751 list_del_init(&zspage
->list
);
752 zs_stat_dec(class, fullness
, 1);
756 * Each size class maintains zspages in different fullness groups depending
757 * on the number of live objects they contain. When allocating or freeing
758 * objects, the fullness status of the page can change, say, from ALMOST_FULL
759 * to ALMOST_EMPTY when freeing an object. This function checks if such
760 * a status change has occurred for the given page and accordingly moves the
761 * page from the freelist of the old fullness group to that of the new
764 static enum fullness_group
fix_fullness_group(struct size_class
*class,
765 struct zspage
*zspage
)
768 enum fullness_group currfg
, newfg
;
770 get_zspage_mapping(zspage
, &class_idx
, &currfg
);
771 newfg
= get_fullness_group(class, zspage
);
775 if (!is_zspage_isolated(zspage
)) {
776 remove_zspage(class, zspage
, currfg
);
777 insert_zspage(class, zspage
, newfg
);
780 set_zspage_mapping(zspage
, class_idx
, newfg
);
787 * We have to decide on how many pages to link together
788 * to form a zspage for each size class. This is important
789 * to reduce wastage due to unusable space left at end of
790 * each zspage which is given as:
791 * wastage = Zp % class_size
792 * usage = Zp - wastage
793 * where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ...
795 * For example, for size class of 3/8 * PAGE_SIZE, we should
796 * link together 3 PAGE_SIZE sized pages to form a zspage
797 * since then we can perfectly fit in 8 such objects.
799 static int get_pages_per_zspage(int class_size
)
801 int i
, max_usedpc
= 0;
802 /* zspage order which gives maximum used size per KB */
803 int max_usedpc_order
= 1;
805 for (i
= 1; i
<= ZS_MAX_PAGES_PER_ZSPAGE
; i
++) {
809 zspage_size
= i
* PAGE_SIZE
;
810 waste
= zspage_size
% class_size
;
811 usedpc
= (zspage_size
- waste
) * 100 / zspage_size
;
813 if (usedpc
> max_usedpc
) {
815 max_usedpc_order
= i
;
819 return max_usedpc_order
;
822 static struct zspage
*get_zspage(struct page
*page
)
824 struct zspage
*zspage
= (struct zspage
*)page
->private;
826 BUG_ON(zspage
->magic
!= ZSPAGE_MAGIC
);
830 static struct page
*get_next_page(struct page
*page
)
832 if (unlikely(PageHugeObject(page
)))
835 return page
->freelist
;
839 * obj_to_location - get (<page>, <obj_idx>) from encoded object value
840 * @obj: the encoded object value
841 * @page: page object resides in zspage
842 * @obj_idx: object index
844 static void obj_to_location(unsigned long obj
, struct page
**page
,
845 unsigned int *obj_idx
)
847 obj
>>= OBJ_TAG_BITS
;
848 *page
= pfn_to_page(obj
>> OBJ_INDEX_BITS
);
849 *obj_idx
= (obj
& OBJ_INDEX_MASK
);
853 * location_to_obj - get obj value encoded from (<page>, <obj_idx>)
854 * @page: page object resides in zspage
855 * @obj_idx: object index
857 static unsigned long location_to_obj(struct page
*page
, unsigned int obj_idx
)
861 obj
= page_to_pfn(page
) << OBJ_INDEX_BITS
;
862 obj
|= obj_idx
& OBJ_INDEX_MASK
;
863 obj
<<= OBJ_TAG_BITS
;
868 static unsigned long handle_to_obj(unsigned long handle
)
870 return *(unsigned long *)handle
;
873 static unsigned long obj_to_head(struct page
*page
, void *obj
)
875 if (unlikely(PageHugeObject(page
))) {
876 VM_BUG_ON_PAGE(!is_first_page(page
), page
);
879 return *(unsigned long *)obj
;
882 static inline int testpin_tag(unsigned long handle
)
884 return bit_spin_is_locked(HANDLE_PIN_BIT
, (unsigned long *)handle
);
887 static inline int trypin_tag(unsigned long handle
)
889 return bit_spin_trylock(HANDLE_PIN_BIT
, (unsigned long *)handle
);
892 static void pin_tag(unsigned long handle
)
894 bit_spin_lock(HANDLE_PIN_BIT
, (unsigned long *)handle
);
897 static void unpin_tag(unsigned long handle
)
899 bit_spin_unlock(HANDLE_PIN_BIT
, (unsigned long *)handle
);
902 static void reset_page(struct page
*page
)
904 __ClearPageMovable(page
);
905 ClearPagePrivate(page
);
906 set_page_private(page
, 0);
907 page_mapcount_reset(page
);
908 ClearPageHugeObject(page
);
909 page
->freelist
= NULL
;
912 static int trylock_zspage(struct zspage
*zspage
)
914 struct page
*cursor
, *fail
;
916 for (cursor
= get_first_page(zspage
); cursor
!= NULL
; cursor
=
917 get_next_page(cursor
)) {
918 if (!trylock_page(cursor
)) {
926 for (cursor
= get_first_page(zspage
); cursor
!= fail
; cursor
=
927 get_next_page(cursor
))
933 static void __free_zspage(struct zs_pool
*pool
, struct size_class
*class,
934 struct zspage
*zspage
)
936 struct page
*page
, *next
;
937 enum fullness_group fg
;
938 unsigned int class_idx
;
940 get_zspage_mapping(zspage
, &class_idx
, &fg
);
942 assert_spin_locked(&class->lock
);
944 VM_BUG_ON(get_zspage_inuse(zspage
));
945 VM_BUG_ON(fg
!= ZS_EMPTY
);
947 next
= page
= get_first_page(zspage
);
949 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
950 next
= get_next_page(page
);
953 dec_zone_page_state(page
, NR_ZSPAGES
);
956 } while (page
!= NULL
);
958 cache_free_zspage(pool
, zspage
);
960 zs_stat_dec(class, OBJ_ALLOCATED
, class->objs_per_zspage
);
961 atomic_long_sub(class->pages_per_zspage
,
962 &pool
->pages_allocated
);
965 static void free_zspage(struct zs_pool
*pool
, struct size_class
*class,
966 struct zspage
*zspage
)
968 VM_BUG_ON(get_zspage_inuse(zspage
));
969 VM_BUG_ON(list_empty(&zspage
->list
));
971 if (!trylock_zspage(zspage
)) {
972 kick_deferred_free(pool
);
976 remove_zspage(class, zspage
, ZS_EMPTY
);
977 __free_zspage(pool
, class, zspage
);
980 /* Initialize a newly allocated zspage */
981 static void init_zspage(struct size_class
*class, struct zspage
*zspage
)
983 unsigned int freeobj
= 1;
984 unsigned long off
= 0;
985 struct page
*page
= get_first_page(zspage
);
988 struct page
*next_page
;
989 struct link_free
*link
;
992 set_first_obj_offset(page
, off
);
994 vaddr
= kmap_atomic(page
);
995 link
= (struct link_free
*)vaddr
+ off
/ sizeof(*link
);
997 while ((off
+= class->size
) < PAGE_SIZE
) {
998 link
->next
= freeobj
++ << OBJ_TAG_BITS
;
999 link
+= class->size
/ sizeof(*link
);
1003 * We now come to the last (full or partial) object on this
1004 * page, which must point to the first object on the next
1007 next_page
= get_next_page(page
);
1009 link
->next
= freeobj
++ << OBJ_TAG_BITS
;
1012 * Reset OBJ_TAG_BITS bit to last link to tell
1013 * whether it's allocated object or not.
1015 link
->next
= -1UL << OBJ_TAG_BITS
;
1017 kunmap_atomic(vaddr
);
1022 set_freeobj(zspage
, 0);
1025 static void create_page_chain(struct size_class
*class, struct zspage
*zspage
,
1026 struct page
*pages
[])
1030 struct page
*prev_page
= NULL
;
1031 int nr_pages
= class->pages_per_zspage
;
1034 * Allocate individual pages and link them together as:
1035 * 1. all pages are linked together using page->freelist
1036 * 2. each sub-page point to zspage using page->private
1038 * we set PG_private to identify the first page (i.e. no other sub-page
1039 * has this flag set).
1041 for (i
= 0; i
< nr_pages
; i
++) {
1043 set_page_private(page
, (unsigned long)zspage
);
1044 page
->freelist
= NULL
;
1046 zspage
->first_page
= page
;
1047 SetPagePrivate(page
);
1048 if (unlikely(class->objs_per_zspage
== 1 &&
1049 class->pages_per_zspage
== 1))
1050 SetPageHugeObject(page
);
1052 prev_page
->freelist
= page
;
1059 * Allocate a zspage for the given size class
1061 static struct zspage
*alloc_zspage(struct zs_pool
*pool
,
1062 struct size_class
*class,
1066 struct page
*pages
[ZS_MAX_PAGES_PER_ZSPAGE
];
1067 struct zspage
*zspage
= cache_alloc_zspage(pool
, gfp
);
1072 memset(zspage
, 0, sizeof(struct zspage
));
1073 zspage
->magic
= ZSPAGE_MAGIC
;
1074 migrate_lock_init(zspage
);
1076 for (i
= 0; i
< class->pages_per_zspage
; i
++) {
1079 page
= alloc_page(gfp
);
1082 dec_zone_page_state(pages
[i
], NR_ZSPAGES
);
1083 __free_page(pages
[i
]);
1085 cache_free_zspage(pool
, zspage
);
1089 inc_zone_page_state(page
, NR_ZSPAGES
);
1093 create_page_chain(class, zspage
, pages
);
1094 init_zspage(class, zspage
);
1099 static struct zspage
*find_get_zspage(struct size_class
*class)
1102 struct zspage
*zspage
;
1104 for (i
= ZS_ALMOST_FULL
; i
>= ZS_EMPTY
; i
--) {
1105 zspage
= list_first_entry_or_null(&class->fullness_list
[i
],
1106 struct zspage
, list
);
1114 #ifdef CONFIG_PGTABLE_MAPPING
1115 static inline int __zs_cpu_up(struct mapping_area
*area
)
1118 * Make sure we don't leak memory if a cpu UP notification
1119 * and zs_init() race and both call zs_cpu_up() on the same cpu
1123 area
->vm
= alloc_vm_area(PAGE_SIZE
* 2, NULL
);
1129 static inline void __zs_cpu_down(struct mapping_area
*area
)
1132 free_vm_area(area
->vm
);
1136 static inline void *__zs_map_object(struct mapping_area
*area
,
1137 struct page
*pages
[2], int off
, int size
)
1139 BUG_ON(map_vm_area(area
->vm
, PAGE_KERNEL
, pages
));
1140 area
->vm_addr
= area
->vm
->addr
;
1141 return area
->vm_addr
+ off
;
1144 static inline void __zs_unmap_object(struct mapping_area
*area
,
1145 struct page
*pages
[2], int off
, int size
)
1147 unsigned long addr
= (unsigned long)area
->vm_addr
;
1149 unmap_kernel_range(addr
, PAGE_SIZE
* 2);
1152 #else /* CONFIG_PGTABLE_MAPPING */
1154 static inline int __zs_cpu_up(struct mapping_area
*area
)
1157 * Make sure we don't leak memory if a cpu UP notification
1158 * and zs_init() race and both call zs_cpu_up() on the same cpu
1162 area
->vm_buf
= kmalloc(ZS_MAX_ALLOC_SIZE
, GFP_KERNEL
);
1168 static inline void __zs_cpu_down(struct mapping_area
*area
)
1170 kfree(area
->vm_buf
);
1171 area
->vm_buf
= NULL
;
1174 static void *__zs_map_object(struct mapping_area
*area
,
1175 struct page
*pages
[2], int off
, int size
)
1179 char *buf
= area
->vm_buf
;
1181 /* disable page faults to match kmap_atomic() return conditions */
1182 pagefault_disable();
1184 /* no read fastpath */
1185 if (area
->vm_mm
== ZS_MM_WO
)
1188 sizes
[0] = PAGE_SIZE
- off
;
1189 sizes
[1] = size
- sizes
[0];
1191 /* copy object to per-cpu buffer */
1192 addr
= kmap_atomic(pages
[0]);
1193 memcpy(buf
, addr
+ off
, sizes
[0]);
1194 kunmap_atomic(addr
);
1195 addr
= kmap_atomic(pages
[1]);
1196 memcpy(buf
+ sizes
[0], addr
, sizes
[1]);
1197 kunmap_atomic(addr
);
1199 return area
->vm_buf
;
1202 static void __zs_unmap_object(struct mapping_area
*area
,
1203 struct page
*pages
[2], int off
, int size
)
1209 /* no write fastpath */
1210 if (area
->vm_mm
== ZS_MM_RO
)
1214 buf
= buf
+ ZS_HANDLE_SIZE
;
1215 size
-= ZS_HANDLE_SIZE
;
1216 off
+= ZS_HANDLE_SIZE
;
1218 sizes
[0] = PAGE_SIZE
- off
;
1219 sizes
[1] = size
- sizes
[0];
1221 /* copy per-cpu buffer to object */
1222 addr
= kmap_atomic(pages
[0]);
1223 memcpy(addr
+ off
, buf
, sizes
[0]);
1224 kunmap_atomic(addr
);
1225 addr
= kmap_atomic(pages
[1]);
1226 memcpy(addr
, buf
+ sizes
[0], sizes
[1]);
1227 kunmap_atomic(addr
);
1230 /* enable page faults to match kunmap_atomic() return conditions */
1234 #endif /* CONFIG_PGTABLE_MAPPING */
1236 static int zs_cpu_prepare(unsigned int cpu
)
1238 struct mapping_area
*area
;
1240 area
= &per_cpu(zs_map_area
, cpu
);
1241 return __zs_cpu_up(area
);
1244 static int zs_cpu_dead(unsigned int cpu
)
1246 struct mapping_area
*area
;
1248 area
= &per_cpu(zs_map_area
, cpu
);
1249 __zs_cpu_down(area
);
1253 static bool can_merge(struct size_class
*prev
, int pages_per_zspage
,
1254 int objs_per_zspage
)
1256 if (prev
->pages_per_zspage
== pages_per_zspage
&&
1257 prev
->objs_per_zspage
== objs_per_zspage
)
1263 static bool zspage_full(struct size_class
*class, struct zspage
*zspage
)
1265 return get_zspage_inuse(zspage
) == class->objs_per_zspage
;
1268 unsigned long zs_get_total_pages(struct zs_pool
*pool
)
1270 return atomic_long_read(&pool
->pages_allocated
);
1272 EXPORT_SYMBOL_GPL(zs_get_total_pages
);
1275 * zs_map_object - get address of allocated object from handle.
1276 * @pool: pool from which the object was allocated
1277 * @handle: handle returned from zs_malloc
1278 * @mm: maping mode to use
1280 * Before using an object allocated from zs_malloc, it must be mapped using
1281 * this function. When done with the object, it must be unmapped using
1284 * Only one object can be mapped per cpu at a time. There is no protection
1285 * against nested mappings.
1287 * This function returns with preemption and page faults disabled.
1289 void *zs_map_object(struct zs_pool
*pool
, unsigned long handle
,
1292 struct zspage
*zspage
;
1294 unsigned long obj
, off
;
1295 unsigned int obj_idx
;
1297 unsigned int class_idx
;
1298 enum fullness_group fg
;
1299 struct size_class
*class;
1300 struct mapping_area
*area
;
1301 struct page
*pages
[2];
1305 * Because we use per-cpu mapping areas shared among the
1306 * pools/users, we can't allow mapping in interrupt context
1307 * because it can corrupt another users mappings.
1309 BUG_ON(in_interrupt());
1311 /* From now on, migration cannot move the object */
1314 obj
= handle_to_obj(handle
);
1315 obj_to_location(obj
, &page
, &obj_idx
);
1316 zspage
= get_zspage(page
);
1318 /* migration cannot move any subpage in this zspage */
1319 migrate_read_lock(zspage
);
1321 get_zspage_mapping(zspage
, &class_idx
, &fg
);
1322 class = pool
->size_class
[class_idx
];
1323 off
= (class->size
* obj_idx
) & ~PAGE_MASK
;
1325 area
= &get_cpu_var(zs_map_area
);
1327 if (off
+ class->size
<= PAGE_SIZE
) {
1328 /* this object is contained entirely within a page */
1329 area
->vm_addr
= kmap_atomic(page
);
1330 ret
= area
->vm_addr
+ off
;
1334 /* this object spans two pages */
1336 pages
[1] = get_next_page(page
);
1339 ret
= __zs_map_object(area
, pages
, off
, class->size
);
1341 if (likely(!PageHugeObject(page
)))
1342 ret
+= ZS_HANDLE_SIZE
;
1346 EXPORT_SYMBOL_GPL(zs_map_object
);
1348 void zs_unmap_object(struct zs_pool
*pool
, unsigned long handle
)
1350 struct zspage
*zspage
;
1352 unsigned long obj
, off
;
1353 unsigned int obj_idx
;
1355 unsigned int class_idx
;
1356 enum fullness_group fg
;
1357 struct size_class
*class;
1358 struct mapping_area
*area
;
1360 obj
= handle_to_obj(handle
);
1361 obj_to_location(obj
, &page
, &obj_idx
);
1362 zspage
= get_zspage(page
);
1363 get_zspage_mapping(zspage
, &class_idx
, &fg
);
1364 class = pool
->size_class
[class_idx
];
1365 off
= (class->size
* obj_idx
) & ~PAGE_MASK
;
1367 area
= this_cpu_ptr(&zs_map_area
);
1368 if (off
+ class->size
<= PAGE_SIZE
)
1369 kunmap_atomic(area
->vm_addr
);
1371 struct page
*pages
[2];
1374 pages
[1] = get_next_page(page
);
1377 __zs_unmap_object(area
, pages
, off
, class->size
);
1379 put_cpu_var(zs_map_area
);
1381 migrate_read_unlock(zspage
);
1384 EXPORT_SYMBOL_GPL(zs_unmap_object
);
1387 * zs_huge_class_size() - Returns the size (in bytes) of the first huge
1388 * zsmalloc &size_class.
1389 * @pool: zsmalloc pool to use
1391 * The function returns the size of the first huge class - any object of equal
1392 * or bigger size will be stored in zspage consisting of a single physical
1395 * Context: Any context.
1397 * Return: the size (in bytes) of the first huge zsmalloc &size_class.
1399 size_t zs_huge_class_size(struct zs_pool
*pool
)
1401 return huge_class_size
;
1403 EXPORT_SYMBOL_GPL(zs_huge_class_size
);
1405 static unsigned long obj_malloc(struct size_class
*class,
1406 struct zspage
*zspage
, unsigned long handle
)
1408 int i
, nr_page
, offset
;
1410 struct link_free
*link
;
1412 struct page
*m_page
;
1413 unsigned long m_offset
;
1416 handle
|= OBJ_ALLOCATED_TAG
;
1417 obj
= get_freeobj(zspage
);
1419 offset
= obj
* class->size
;
1420 nr_page
= offset
>> PAGE_SHIFT
;
1421 m_offset
= offset
& ~PAGE_MASK
;
1422 m_page
= get_first_page(zspage
);
1424 for (i
= 0; i
< nr_page
; i
++)
1425 m_page
= get_next_page(m_page
);
1427 vaddr
= kmap_atomic(m_page
);
1428 link
= (struct link_free
*)vaddr
+ m_offset
/ sizeof(*link
);
1429 set_freeobj(zspage
, link
->next
>> OBJ_TAG_BITS
);
1430 if (likely(!PageHugeObject(m_page
)))
1431 /* record handle in the header of allocated chunk */
1432 link
->handle
= handle
;
1434 /* record handle to page->index */
1435 zspage
->first_page
->index
= handle
;
1437 kunmap_atomic(vaddr
);
1438 mod_zspage_inuse(zspage
, 1);
1439 zs_stat_inc(class, OBJ_USED
, 1);
1441 obj
= location_to_obj(m_page
, obj
);
1448 * zs_malloc - Allocate block of given size from pool.
1449 * @pool: pool to allocate from
1450 * @size: size of block to allocate
1451 * @gfp: gfp flags when allocating object
1453 * On success, handle to the allocated object is returned,
1455 * Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
1457 unsigned long zs_malloc(struct zs_pool
*pool
, size_t size
, gfp_t gfp
)
1459 unsigned long handle
, obj
;
1460 struct size_class
*class;
1461 enum fullness_group newfg
;
1462 struct zspage
*zspage
;
1464 if (unlikely(!size
|| size
> ZS_MAX_ALLOC_SIZE
))
1467 handle
= cache_alloc_handle(pool
, gfp
);
1471 /* extra space in chunk to keep the handle */
1472 size
+= ZS_HANDLE_SIZE
;
1473 class = pool
->size_class
[get_size_class_index(size
)];
1475 spin_lock(&class->lock
);
1476 zspage
= find_get_zspage(class);
1477 if (likely(zspage
)) {
1478 obj
= obj_malloc(class, zspage
, handle
);
1479 /* Now move the zspage to another fullness group, if required */
1480 fix_fullness_group(class, zspage
);
1481 record_obj(handle
, obj
);
1482 spin_unlock(&class->lock
);
1487 spin_unlock(&class->lock
);
1489 zspage
= alloc_zspage(pool
, class, gfp
);
1491 cache_free_handle(pool
, handle
);
1495 spin_lock(&class->lock
);
1496 obj
= obj_malloc(class, zspage
, handle
);
1497 newfg
= get_fullness_group(class, zspage
);
1498 insert_zspage(class, zspage
, newfg
);
1499 set_zspage_mapping(zspage
, class->index
, newfg
);
1500 record_obj(handle
, obj
);
1501 atomic_long_add(class->pages_per_zspage
,
1502 &pool
->pages_allocated
);
1503 zs_stat_inc(class, OBJ_ALLOCATED
, class->objs_per_zspage
);
1505 /* We completely set up zspage so mark them as movable */
1506 SetZsPageMovable(pool
, zspage
);
1507 spin_unlock(&class->lock
);
1511 EXPORT_SYMBOL_GPL(zs_malloc
);
1513 static void obj_free(struct size_class
*class, unsigned long obj
)
1515 struct link_free
*link
;
1516 struct zspage
*zspage
;
1517 struct page
*f_page
;
1518 unsigned long f_offset
;
1519 unsigned int f_objidx
;
1522 obj
&= ~OBJ_ALLOCATED_TAG
;
1523 obj_to_location(obj
, &f_page
, &f_objidx
);
1524 f_offset
= (class->size
* f_objidx
) & ~PAGE_MASK
;
1525 zspage
= get_zspage(f_page
);
1527 vaddr
= kmap_atomic(f_page
);
1529 /* Insert this object in containing zspage's freelist */
1530 link
= (struct link_free
*)(vaddr
+ f_offset
);
1531 link
->next
= get_freeobj(zspage
) << OBJ_TAG_BITS
;
1532 kunmap_atomic(vaddr
);
1533 set_freeobj(zspage
, f_objidx
);
1534 mod_zspage_inuse(zspage
, -1);
1535 zs_stat_dec(class, OBJ_USED
, 1);
1538 void zs_free(struct zs_pool
*pool
, unsigned long handle
)
1540 struct zspage
*zspage
;
1541 struct page
*f_page
;
1543 unsigned int f_objidx
;
1545 struct size_class
*class;
1546 enum fullness_group fullness
;
1549 if (unlikely(!handle
))
1553 obj
= handle_to_obj(handle
);
1554 obj_to_location(obj
, &f_page
, &f_objidx
);
1555 zspage
= get_zspage(f_page
);
1557 migrate_read_lock(zspage
);
1559 get_zspage_mapping(zspage
, &class_idx
, &fullness
);
1560 class = pool
->size_class
[class_idx
];
1562 spin_lock(&class->lock
);
1563 obj_free(class, obj
);
1564 fullness
= fix_fullness_group(class, zspage
);
1565 if (fullness
!= ZS_EMPTY
) {
1566 migrate_read_unlock(zspage
);
1570 isolated
= is_zspage_isolated(zspage
);
1571 migrate_read_unlock(zspage
);
1572 /* If zspage is isolated, zs_page_putback will free the zspage */
1573 if (likely(!isolated
))
1574 free_zspage(pool
, class, zspage
);
1577 spin_unlock(&class->lock
);
1579 cache_free_handle(pool
, handle
);
1581 EXPORT_SYMBOL_GPL(zs_free
);
1583 static void zs_object_copy(struct size_class
*class, unsigned long dst
,
1586 struct page
*s_page
, *d_page
;
1587 unsigned int s_objidx
, d_objidx
;
1588 unsigned long s_off
, d_off
;
1589 void *s_addr
, *d_addr
;
1590 int s_size
, d_size
, size
;
1593 s_size
= d_size
= class->size
;
1595 obj_to_location(src
, &s_page
, &s_objidx
);
1596 obj_to_location(dst
, &d_page
, &d_objidx
);
1598 s_off
= (class->size
* s_objidx
) & ~PAGE_MASK
;
1599 d_off
= (class->size
* d_objidx
) & ~PAGE_MASK
;
1601 if (s_off
+ class->size
> PAGE_SIZE
)
1602 s_size
= PAGE_SIZE
- s_off
;
1604 if (d_off
+ class->size
> PAGE_SIZE
)
1605 d_size
= PAGE_SIZE
- d_off
;
1607 s_addr
= kmap_atomic(s_page
);
1608 d_addr
= kmap_atomic(d_page
);
1611 size
= min(s_size
, d_size
);
1612 memcpy(d_addr
+ d_off
, s_addr
+ s_off
, size
);
1615 if (written
== class->size
)
1623 if (s_off
>= PAGE_SIZE
) {
1624 kunmap_atomic(d_addr
);
1625 kunmap_atomic(s_addr
);
1626 s_page
= get_next_page(s_page
);
1627 s_addr
= kmap_atomic(s_page
);
1628 d_addr
= kmap_atomic(d_page
);
1629 s_size
= class->size
- written
;
1633 if (d_off
>= PAGE_SIZE
) {
1634 kunmap_atomic(d_addr
);
1635 d_page
= get_next_page(d_page
);
1636 d_addr
= kmap_atomic(d_page
);
1637 d_size
= class->size
- written
;
1642 kunmap_atomic(d_addr
);
1643 kunmap_atomic(s_addr
);
1647 * Find alloced object in zspage from index object and
1650 static unsigned long find_alloced_obj(struct size_class
*class,
1651 struct page
*page
, int *obj_idx
)
1655 int index
= *obj_idx
;
1656 unsigned long handle
= 0;
1657 void *addr
= kmap_atomic(page
);
1659 offset
= get_first_obj_offset(page
);
1660 offset
+= class->size
* index
;
1662 while (offset
< PAGE_SIZE
) {
1663 head
= obj_to_head(page
, addr
+ offset
);
1664 if (head
& OBJ_ALLOCATED_TAG
) {
1665 handle
= head
& ~OBJ_ALLOCATED_TAG
;
1666 if (trypin_tag(handle
))
1671 offset
+= class->size
;
1675 kunmap_atomic(addr
);
1682 struct zs_compact_control
{
1683 /* Source spage for migration which could be a subpage of zspage */
1684 struct page
*s_page
;
1685 /* Destination page for migration which should be a first page
1687 struct page
*d_page
;
1688 /* Starting object index within @s_page which used for live object
1689 * in the subpage. */
1693 static int migrate_zspage(struct zs_pool
*pool
, struct size_class
*class,
1694 struct zs_compact_control
*cc
)
1696 unsigned long used_obj
, free_obj
;
1697 unsigned long handle
;
1698 struct page
*s_page
= cc
->s_page
;
1699 struct page
*d_page
= cc
->d_page
;
1700 int obj_idx
= cc
->obj_idx
;
1704 handle
= find_alloced_obj(class, s_page
, &obj_idx
);
1706 s_page
= get_next_page(s_page
);
1713 /* Stop if there is no more space */
1714 if (zspage_full(class, get_zspage(d_page
))) {
1720 used_obj
= handle_to_obj(handle
);
1721 free_obj
= obj_malloc(class, get_zspage(d_page
), handle
);
1722 zs_object_copy(class, free_obj
, used_obj
);
1725 * record_obj updates handle's value to free_obj and it will
1726 * invalidate lock bit(ie, HANDLE_PIN_BIT) of handle, which
1727 * breaks synchronization using pin_tag(e,g, zs_free) so
1728 * let's keep the lock bit.
1730 free_obj
|= BIT(HANDLE_PIN_BIT
);
1731 record_obj(handle
, free_obj
);
1733 obj_free(class, used_obj
);
1736 /* Remember last position in this iteration */
1737 cc
->s_page
= s_page
;
1738 cc
->obj_idx
= obj_idx
;
1743 static struct zspage
*isolate_zspage(struct size_class
*class, bool source
)
1746 struct zspage
*zspage
;
1747 enum fullness_group fg
[2] = {ZS_ALMOST_EMPTY
, ZS_ALMOST_FULL
};
1750 fg
[0] = ZS_ALMOST_FULL
;
1751 fg
[1] = ZS_ALMOST_EMPTY
;
1754 for (i
= 0; i
< 2; i
++) {
1755 zspage
= list_first_entry_or_null(&class->fullness_list
[fg
[i
]],
1756 struct zspage
, list
);
1758 VM_BUG_ON(is_zspage_isolated(zspage
));
1759 remove_zspage(class, zspage
, fg
[i
]);
1768 * putback_zspage - add @zspage into right class's fullness list
1769 * @class: destination class
1770 * @zspage: target page
1772 * Return @zspage's fullness_group
1774 static enum fullness_group
putback_zspage(struct size_class
*class,
1775 struct zspage
*zspage
)
1777 enum fullness_group fullness
;
1779 VM_BUG_ON(is_zspage_isolated(zspage
));
1781 fullness
= get_fullness_group(class, zspage
);
1782 insert_zspage(class, zspage
, fullness
);
1783 set_zspage_mapping(zspage
, class->index
, fullness
);
1788 #ifdef CONFIG_COMPACTION
1790 * To prevent zspage destroy during migration, zspage freeing should
1791 * hold locks of all pages in the zspage.
1793 static void lock_zspage(struct zspage
*zspage
)
1795 struct page
*page
= get_first_page(zspage
);
1799 } while ((page
= get_next_page(page
)) != NULL
);
1802 static int zs_init_fs_context(struct fs_context
*fc
)
1804 return init_pseudo(fc
, ZSMALLOC_MAGIC
) ? 0 : -ENOMEM
;
1807 static struct file_system_type zsmalloc_fs
= {
1809 .init_fs_context
= zs_init_fs_context
,
1810 .kill_sb
= kill_anon_super
,
1813 static int zsmalloc_mount(void)
1817 zsmalloc_mnt
= kern_mount(&zsmalloc_fs
);
1818 if (IS_ERR(zsmalloc_mnt
))
1819 ret
= PTR_ERR(zsmalloc_mnt
);
1824 static void zsmalloc_unmount(void)
1826 kern_unmount(zsmalloc_mnt
);
1829 static void migrate_lock_init(struct zspage
*zspage
)
1831 rwlock_init(&zspage
->lock
);
1834 static void migrate_read_lock(struct zspage
*zspage
)
1836 read_lock(&zspage
->lock
);
1839 static void migrate_read_unlock(struct zspage
*zspage
)
1841 read_unlock(&zspage
->lock
);
1844 static void migrate_write_lock(struct zspage
*zspage
)
1846 write_lock(&zspage
->lock
);
1849 static void migrate_write_unlock(struct zspage
*zspage
)
1851 write_unlock(&zspage
->lock
);
1854 /* Number of isolated subpage for *page migration* in this zspage */
1855 static void inc_zspage_isolation(struct zspage
*zspage
)
1860 static void dec_zspage_isolation(struct zspage
*zspage
)
1865 static void replace_sub_page(struct size_class
*class, struct zspage
*zspage
,
1866 struct page
*newpage
, struct page
*oldpage
)
1869 struct page
*pages
[ZS_MAX_PAGES_PER_ZSPAGE
] = {NULL
, };
1872 page
= get_first_page(zspage
);
1874 if (page
== oldpage
)
1875 pages
[idx
] = newpage
;
1879 } while ((page
= get_next_page(page
)) != NULL
);
1881 create_page_chain(class, zspage
, pages
);
1882 set_first_obj_offset(newpage
, get_first_obj_offset(oldpage
));
1883 if (unlikely(PageHugeObject(oldpage
)))
1884 newpage
->index
= oldpage
->index
;
1885 __SetPageMovable(newpage
, page_mapping(oldpage
));
1888 static bool zs_page_isolate(struct page
*page
, isolate_mode_t mode
)
1890 struct zs_pool
*pool
;
1891 struct size_class
*class;
1893 enum fullness_group fullness
;
1894 struct zspage
*zspage
;
1895 struct address_space
*mapping
;
1898 * Page is locked so zspage couldn't be destroyed. For detail, look at
1899 * lock_zspage in free_zspage.
1901 VM_BUG_ON_PAGE(!PageMovable(page
), page
);
1902 VM_BUG_ON_PAGE(PageIsolated(page
), page
);
1904 zspage
= get_zspage(page
);
1907 * Without class lock, fullness could be stale while class_idx is okay
1908 * because class_idx is constant unless page is freed so we should get
1909 * fullness again under class lock.
1911 get_zspage_mapping(zspage
, &class_idx
, &fullness
);
1912 mapping
= page_mapping(page
);
1913 pool
= mapping
->private_data
;
1914 class = pool
->size_class
[class_idx
];
1916 spin_lock(&class->lock
);
1917 if (get_zspage_inuse(zspage
) == 0) {
1918 spin_unlock(&class->lock
);
1922 /* zspage is isolated for object migration */
1923 if (list_empty(&zspage
->list
) && !is_zspage_isolated(zspage
)) {
1924 spin_unlock(&class->lock
);
1929 * If this is first time isolation for the zspage, isolate zspage from
1930 * size_class to prevent further object allocation from the zspage.
1932 if (!list_empty(&zspage
->list
) && !is_zspage_isolated(zspage
)) {
1933 get_zspage_mapping(zspage
, &class_idx
, &fullness
);
1934 remove_zspage(class, zspage
, fullness
);
1937 inc_zspage_isolation(zspage
);
1938 spin_unlock(&class->lock
);
1943 static int zs_page_migrate(struct address_space
*mapping
, struct page
*newpage
,
1944 struct page
*page
, enum migrate_mode mode
)
1946 struct zs_pool
*pool
;
1947 struct size_class
*class;
1949 enum fullness_group fullness
;
1950 struct zspage
*zspage
;
1952 void *s_addr
, *d_addr
, *addr
;
1954 unsigned long handle
, head
;
1955 unsigned long old_obj
, new_obj
;
1956 unsigned int obj_idx
;
1960 * We cannot support the _NO_COPY case here, because copy needs to
1961 * happen under the zs lock, which does not work with
1962 * MIGRATE_SYNC_NO_COPY workflow.
1964 if (mode
== MIGRATE_SYNC_NO_COPY
)
1967 VM_BUG_ON_PAGE(!PageMovable(page
), page
);
1968 VM_BUG_ON_PAGE(!PageIsolated(page
), page
);
1970 zspage
= get_zspage(page
);
1972 /* Concurrent compactor cannot migrate any subpage in zspage */
1973 migrate_write_lock(zspage
);
1974 get_zspage_mapping(zspage
, &class_idx
, &fullness
);
1975 pool
= mapping
->private_data
;
1976 class = pool
->size_class
[class_idx
];
1977 offset
= get_first_obj_offset(page
);
1979 spin_lock(&class->lock
);
1980 if (!get_zspage_inuse(zspage
)) {
1982 * Set "offset" to end of the page so that every loops
1983 * skips unnecessary object scanning.
1989 s_addr
= kmap_atomic(page
);
1990 while (pos
< PAGE_SIZE
) {
1991 head
= obj_to_head(page
, s_addr
+ pos
);
1992 if (head
& OBJ_ALLOCATED_TAG
) {
1993 handle
= head
& ~OBJ_ALLOCATED_TAG
;
1994 if (!trypin_tag(handle
))
2001 * Here, any user cannot access all objects in the zspage so let's move.
2003 d_addr
= kmap_atomic(newpage
);
2004 memcpy(d_addr
, s_addr
, PAGE_SIZE
);
2005 kunmap_atomic(d_addr
);
2007 for (addr
= s_addr
+ offset
; addr
< s_addr
+ pos
;
2008 addr
+= class->size
) {
2009 head
= obj_to_head(page
, addr
);
2010 if (head
& OBJ_ALLOCATED_TAG
) {
2011 handle
= head
& ~OBJ_ALLOCATED_TAG
;
2012 if (!testpin_tag(handle
))
2015 old_obj
= handle_to_obj(handle
);
2016 obj_to_location(old_obj
, &dummy
, &obj_idx
);
2017 new_obj
= (unsigned long)location_to_obj(newpage
,
2019 new_obj
|= BIT(HANDLE_PIN_BIT
);
2020 record_obj(handle
, new_obj
);
2024 replace_sub_page(class, zspage
, newpage
, page
);
2027 dec_zspage_isolation(zspage
);
2030 * Page migration is done so let's putback isolated zspage to
2031 * the list if @page is final isolated subpage in the zspage.
2033 if (!is_zspage_isolated(zspage
))
2034 putback_zspage(class, zspage
);
2040 ret
= MIGRATEPAGE_SUCCESS
;
2042 for (addr
= s_addr
+ offset
; addr
< s_addr
+ pos
;
2043 addr
+= class->size
) {
2044 head
= obj_to_head(page
, addr
);
2045 if (head
& OBJ_ALLOCATED_TAG
) {
2046 handle
= head
& ~OBJ_ALLOCATED_TAG
;
2047 if (!testpin_tag(handle
))
2052 kunmap_atomic(s_addr
);
2053 spin_unlock(&class->lock
);
2054 migrate_write_unlock(zspage
);
2059 static void zs_page_putback(struct page
*page
)
2061 struct zs_pool
*pool
;
2062 struct size_class
*class;
2064 enum fullness_group fg
;
2065 struct address_space
*mapping
;
2066 struct zspage
*zspage
;
2068 VM_BUG_ON_PAGE(!PageMovable(page
), page
);
2069 VM_BUG_ON_PAGE(!PageIsolated(page
), page
);
2071 zspage
= get_zspage(page
);
2072 get_zspage_mapping(zspage
, &class_idx
, &fg
);
2073 mapping
= page_mapping(page
);
2074 pool
= mapping
->private_data
;
2075 class = pool
->size_class
[class_idx
];
2077 spin_lock(&class->lock
);
2078 dec_zspage_isolation(zspage
);
2079 if (!is_zspage_isolated(zspage
)) {
2080 fg
= putback_zspage(class, zspage
);
2082 * Due to page_lock, we cannot free zspage immediately
2086 schedule_work(&pool
->free_work
);
2088 spin_unlock(&class->lock
);
2091 static const struct address_space_operations zsmalloc_aops
= {
2092 .isolate_page
= zs_page_isolate
,
2093 .migratepage
= zs_page_migrate
,
2094 .putback_page
= zs_page_putback
,
2097 static int zs_register_migration(struct zs_pool
*pool
)
2099 pool
->inode
= alloc_anon_inode(zsmalloc_mnt
->mnt_sb
);
2100 if (IS_ERR(pool
->inode
)) {
2105 pool
->inode
->i_mapping
->private_data
= pool
;
2106 pool
->inode
->i_mapping
->a_ops
= &zsmalloc_aops
;
2110 static void zs_unregister_migration(struct zs_pool
*pool
)
2112 flush_work(&pool
->free_work
);
2117 * Caller should hold page_lock of all pages in the zspage
2118 * In here, we cannot use zspage meta data.
2120 static void async_free_zspage(struct work_struct
*work
)
2123 struct size_class
*class;
2124 unsigned int class_idx
;
2125 enum fullness_group fullness
;
2126 struct zspage
*zspage
, *tmp
;
2127 LIST_HEAD(free_pages
);
2128 struct zs_pool
*pool
= container_of(work
, struct zs_pool
,
2131 for (i
= 0; i
< ZS_SIZE_CLASSES
; i
++) {
2132 class = pool
->size_class
[i
];
2133 if (class->index
!= i
)
2136 spin_lock(&class->lock
);
2137 list_splice_init(&class->fullness_list
[ZS_EMPTY
], &free_pages
);
2138 spin_unlock(&class->lock
);
2142 list_for_each_entry_safe(zspage
, tmp
, &free_pages
, list
) {
2143 list_del(&zspage
->list
);
2144 lock_zspage(zspage
);
2146 get_zspage_mapping(zspage
, &class_idx
, &fullness
);
2147 VM_BUG_ON(fullness
!= ZS_EMPTY
);
2148 class = pool
->size_class
[class_idx
];
2149 spin_lock(&class->lock
);
2150 __free_zspage(pool
, pool
->size_class
[class_idx
], zspage
);
2151 spin_unlock(&class->lock
);
2155 static void kick_deferred_free(struct zs_pool
*pool
)
2157 schedule_work(&pool
->free_work
);
2160 static void init_deferred_free(struct zs_pool
*pool
)
2162 INIT_WORK(&pool
->free_work
, async_free_zspage
);
2165 static void SetZsPageMovable(struct zs_pool
*pool
, struct zspage
*zspage
)
2167 struct page
*page
= get_first_page(zspage
);
2170 WARN_ON(!trylock_page(page
));
2171 __SetPageMovable(page
, pool
->inode
->i_mapping
);
2173 } while ((page
= get_next_page(page
)) != NULL
);
2179 * Based on the number of unused allocated objects calculate
2180 * and return the number of pages that we can free.
2182 static unsigned long zs_can_compact(struct size_class
*class)
2184 unsigned long obj_wasted
;
2185 unsigned long obj_allocated
= zs_stat_get(class, OBJ_ALLOCATED
);
2186 unsigned long obj_used
= zs_stat_get(class, OBJ_USED
);
2188 if (obj_allocated
<= obj_used
)
2191 obj_wasted
= obj_allocated
- obj_used
;
2192 obj_wasted
/= class->objs_per_zspage
;
2194 return obj_wasted
* class->pages_per_zspage
;
2197 static void __zs_compact(struct zs_pool
*pool
, struct size_class
*class)
2199 struct zs_compact_control cc
;
2200 struct zspage
*src_zspage
;
2201 struct zspage
*dst_zspage
= NULL
;
2203 spin_lock(&class->lock
);
2204 while ((src_zspage
= isolate_zspage(class, true))) {
2206 if (!zs_can_compact(class))
2210 cc
.s_page
= get_first_page(src_zspage
);
2212 while ((dst_zspage
= isolate_zspage(class, false))) {
2213 cc
.d_page
= get_first_page(dst_zspage
);
2215 * If there is no more space in dst_page, resched
2216 * and see if anyone had allocated another zspage.
2218 if (!migrate_zspage(pool
, class, &cc
))
2221 putback_zspage(class, dst_zspage
);
2224 /* Stop if we couldn't find slot */
2225 if (dst_zspage
== NULL
)
2228 putback_zspage(class, dst_zspage
);
2229 if (putback_zspage(class, src_zspage
) == ZS_EMPTY
) {
2230 free_zspage(pool
, class, src_zspage
);
2231 pool
->stats
.pages_compacted
+= class->pages_per_zspage
;
2233 spin_unlock(&class->lock
);
2235 spin_lock(&class->lock
);
2239 putback_zspage(class, src_zspage
);
2241 spin_unlock(&class->lock
);
2244 unsigned long zs_compact(struct zs_pool
*pool
)
2247 struct size_class
*class;
2249 for (i
= ZS_SIZE_CLASSES
- 1; i
>= 0; i
--) {
2250 class = pool
->size_class
[i
];
2253 if (class->index
!= i
)
2255 __zs_compact(pool
, class);
2258 return pool
->stats
.pages_compacted
;
2260 EXPORT_SYMBOL_GPL(zs_compact
);
2262 void zs_pool_stats(struct zs_pool
*pool
, struct zs_pool_stats
*stats
)
2264 memcpy(stats
, &pool
->stats
, sizeof(struct zs_pool_stats
));
2266 EXPORT_SYMBOL_GPL(zs_pool_stats
);
2268 static unsigned long zs_shrinker_scan(struct shrinker
*shrinker
,
2269 struct shrink_control
*sc
)
2271 unsigned long pages_freed
;
2272 struct zs_pool
*pool
= container_of(shrinker
, struct zs_pool
,
2275 pages_freed
= pool
->stats
.pages_compacted
;
2277 * Compact classes and calculate compaction delta.
2278 * Can run concurrently with a manually triggered
2279 * (by user) compaction.
2281 pages_freed
= zs_compact(pool
) - pages_freed
;
2283 return pages_freed
? pages_freed
: SHRINK_STOP
;
2286 static unsigned long zs_shrinker_count(struct shrinker
*shrinker
,
2287 struct shrink_control
*sc
)
2290 struct size_class
*class;
2291 unsigned long pages_to_free
= 0;
2292 struct zs_pool
*pool
= container_of(shrinker
, struct zs_pool
,
2295 for (i
= ZS_SIZE_CLASSES
- 1; i
>= 0; i
--) {
2296 class = pool
->size_class
[i
];
2299 if (class->index
!= i
)
2302 pages_to_free
+= zs_can_compact(class);
2305 return pages_to_free
;
2308 static void zs_unregister_shrinker(struct zs_pool
*pool
)
2310 unregister_shrinker(&pool
->shrinker
);
2313 static int zs_register_shrinker(struct zs_pool
*pool
)
2315 pool
->shrinker
.scan_objects
= zs_shrinker_scan
;
2316 pool
->shrinker
.count_objects
= zs_shrinker_count
;
2317 pool
->shrinker
.batch
= 0;
2318 pool
->shrinker
.seeks
= DEFAULT_SEEKS
;
2320 return register_shrinker(&pool
->shrinker
);
2324 * zs_create_pool - Creates an allocation pool to work from.
2325 * @name: pool name to be created
2327 * This function must be called before anything when using
2328 * the zsmalloc allocator.
2330 * On success, a pointer to the newly created pool is returned,
2333 struct zs_pool
*zs_create_pool(const char *name
)
2336 struct zs_pool
*pool
;
2337 struct size_class
*prev_class
= NULL
;
2339 pool
= kzalloc(sizeof(*pool
), GFP_KERNEL
);
2343 init_deferred_free(pool
);
2345 pool
->name
= kstrdup(name
, GFP_KERNEL
);
2349 if (create_cache(pool
))
2353 * Iterate reversely, because, size of size_class that we want to use
2354 * for merging should be larger or equal to current size.
2356 for (i
= ZS_SIZE_CLASSES
- 1; i
>= 0; i
--) {
2358 int pages_per_zspage
;
2359 int objs_per_zspage
;
2360 struct size_class
*class;
2363 size
= ZS_MIN_ALLOC_SIZE
+ i
* ZS_SIZE_CLASS_DELTA
;
2364 if (size
> ZS_MAX_ALLOC_SIZE
)
2365 size
= ZS_MAX_ALLOC_SIZE
;
2366 pages_per_zspage
= get_pages_per_zspage(size
);
2367 objs_per_zspage
= pages_per_zspage
* PAGE_SIZE
/ size
;
2370 * We iterate from biggest down to smallest classes,
2371 * so huge_class_size holds the size of the first huge
2372 * class. Any object bigger than or equal to that will
2373 * endup in the huge class.
2375 if (pages_per_zspage
!= 1 && objs_per_zspage
!= 1 &&
2377 huge_class_size
= size
;
2379 * The object uses ZS_HANDLE_SIZE bytes to store the
2380 * handle. We need to subtract it, because zs_malloc()
2381 * unconditionally adds handle size before it performs
2382 * size class search - so object may be smaller than
2383 * huge class size, yet it still can end up in the huge
2384 * class because it grows by ZS_HANDLE_SIZE extra bytes
2385 * right before class lookup.
2387 huge_class_size
-= (ZS_HANDLE_SIZE
- 1);
2391 * size_class is used for normal zsmalloc operation such
2392 * as alloc/free for that size. Although it is natural that we
2393 * have one size_class for each size, there is a chance that we
2394 * can get more memory utilization if we use one size_class for
2395 * many different sizes whose size_class have same
2396 * characteristics. So, we makes size_class point to
2397 * previous size_class if possible.
2400 if (can_merge(prev_class
, pages_per_zspage
, objs_per_zspage
)) {
2401 pool
->size_class
[i
] = prev_class
;
2406 class = kzalloc(sizeof(struct size_class
), GFP_KERNEL
);
2412 class->pages_per_zspage
= pages_per_zspage
;
2413 class->objs_per_zspage
= objs_per_zspage
;
2414 spin_lock_init(&class->lock
);
2415 pool
->size_class
[i
] = class;
2416 for (fullness
= ZS_EMPTY
; fullness
< NR_ZS_FULLNESS
;
2418 INIT_LIST_HEAD(&class->fullness_list
[fullness
]);
2423 /* debug only, don't abort if it fails */
2424 zs_pool_stat_create(pool
, name
);
2426 if (zs_register_migration(pool
))
2430 * Not critical since shrinker is only used to trigger internal
2431 * defragmentation of the pool which is pretty optional thing. If
2432 * registration fails we still can use the pool normally and user can
2433 * trigger compaction manually. Thus, ignore return code.
2435 zs_register_shrinker(pool
);
2440 zs_destroy_pool(pool
);
2443 EXPORT_SYMBOL_GPL(zs_create_pool
);
2445 void zs_destroy_pool(struct zs_pool
*pool
)
2449 zs_unregister_shrinker(pool
);
2450 zs_unregister_migration(pool
);
2451 zs_pool_stat_destroy(pool
);
2453 for (i
= 0; i
< ZS_SIZE_CLASSES
; i
++) {
2455 struct size_class
*class = pool
->size_class
[i
];
2460 if (class->index
!= i
)
2463 for (fg
= ZS_EMPTY
; fg
< NR_ZS_FULLNESS
; fg
++) {
2464 if (!list_empty(&class->fullness_list
[fg
])) {
2465 pr_info("Freeing non-empty class with size %db, fullness group %d\n",
2472 destroy_cache(pool
);
2476 EXPORT_SYMBOL_GPL(zs_destroy_pool
);
2478 static int __init
zs_init(void)
2482 ret
= zsmalloc_mount();
2486 ret
= cpuhp_setup_state(CPUHP_MM_ZS_PREPARE
, "mm/zsmalloc:prepare",
2487 zs_cpu_prepare
, zs_cpu_dead
);
2492 zpool_register_driver(&zs_zpool_driver
);
2505 static void __exit
zs_exit(void)
2508 zpool_unregister_driver(&zs_zpool_driver
);
2511 cpuhp_remove_state(CPUHP_MM_ZS_PREPARE
);
2516 module_init(zs_init
);
2517 module_exit(zs_exit
);
2519 MODULE_LICENSE("Dual BSD/GPL");
2520 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");