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 <linux/pgtable.h>
43 #include <asm/tlbflush.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/wait.h>
58 #include <linux/pagemap.h>
61 #define ZSPAGE_MAGIC 0x58
64 * This must be power of 2 and greater than or equal to sizeof(link_free).
65 * These two conditions ensure that any 'struct link_free' itself doesn't
66 * span more than 1 page which avoids complex case of mapping 2 pages simply
67 * to restore link_free pointer values.
72 * A single 'zspage' is composed of up to 2^N discontiguous 0-order (single)
73 * pages. ZS_MAX_ZSPAGE_ORDER defines upper limit on N.
75 #define ZS_MAX_ZSPAGE_ORDER 2
76 #define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER)
78 #define ZS_HANDLE_SIZE (sizeof(unsigned long))
81 * Object location (<PFN>, <obj_idx>) is encoded as
82 * a single (unsigned long) handle value.
84 * Note that object index <obj_idx> starts from 0.
86 * This is made more complicated by various memory models and PAE.
89 #ifndef MAX_POSSIBLE_PHYSMEM_BITS
90 #ifdef MAX_PHYSMEM_BITS
91 #define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS
94 * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just
97 #define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG
101 #define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT)
104 * Memory for allocating for handle keeps object position by
105 * encoding <page, obj_idx> and the encoded value has a room
106 * in least bit(ie, look at obj_to_location).
107 * We use the bit to synchronize between object access by
108 * user and migration.
110 #define HANDLE_PIN_BIT 0
113 * Head in allocated object should have OBJ_ALLOCATED_TAG
114 * to identify the object was allocated or not.
115 * It's okay to add the status bit in the least bit because
116 * header keeps handle which is 4byte-aligned address so we
117 * have room for two bit at least.
119 #define OBJ_ALLOCATED_TAG 1
120 #define OBJ_TAG_BITS 1
121 #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
122 #define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
124 #define FULLNESS_BITS 2
126 #define ISOLATED_BITS 3
127 #define MAGIC_VAL_BITS 8
129 #define MAX(a, b) ((a) >= (b) ? (a) : (b))
130 /* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
131 #define ZS_MIN_ALLOC_SIZE \
132 MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
133 /* each chunk includes extra space to keep handle */
134 #define ZS_MAX_ALLOC_SIZE PAGE_SIZE
137 * On systems with 4K page size, this gives 255 size classes! There is a
139 * - Large number of size classes is potentially wasteful as free page are
140 * spread across these classes
141 * - Small number of size classes causes large internal fragmentation
142 * - Probably its better to use specific size classes (empirically
143 * determined). NOTE: all those class sizes must be set as multiple of
144 * ZS_ALIGN to make sure link_free itself never has to span 2 pages.
146 * ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN
149 #define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> CLASS_BITS)
150 #define ZS_SIZE_CLASSES (DIV_ROUND_UP(ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE, \
151 ZS_SIZE_CLASS_DELTA) + 1)
153 enum fullness_group
{
171 struct zs_size_stat
{
172 unsigned long objs
[NR_ZS_STAT_TYPE
];
175 #ifdef CONFIG_ZSMALLOC_STAT
176 static struct dentry
*zs_stat_root
;
179 #ifdef CONFIG_COMPACTION
180 static struct vfsmount
*zsmalloc_mnt
;
184 * We assign a page to ZS_ALMOST_EMPTY fullness group when:
186 * n = number of allocated objects
187 * N = total number of objects zspage can store
188 * f = fullness_threshold_frac
190 * Similarly, we assign zspage to:
191 * ZS_ALMOST_FULL when n > N / f
192 * ZS_EMPTY when n == 0
193 * ZS_FULL when n == N
195 * (see: fix_fullness_group())
197 static const int fullness_threshold_frac
= 4;
198 static size_t huge_class_size
;
202 struct list_head fullness_list
[NR_ZS_FULLNESS
];
204 * Size of objects stored in this class. Must be multiple
209 /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
210 int pages_per_zspage
;
213 struct zs_size_stat stats
;
216 /* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
217 static void SetPageHugeObject(struct page
*page
)
219 SetPageOwnerPriv1(page
);
222 static void ClearPageHugeObject(struct page
*page
)
224 ClearPageOwnerPriv1(page
);
227 static int PageHugeObject(struct page
*page
)
229 return PageOwnerPriv1(page
);
233 * Placed within free objects to form a singly linked list.
234 * For every zspage, zspage->freeobj gives head of this list.
236 * This must be power of 2 and less than or equal to ZS_ALIGN
242 * It's valid for non-allocated object
246 * Handle of allocated object.
248 unsigned long handle
;
255 struct size_class
*size_class
[ZS_SIZE_CLASSES
];
256 struct kmem_cache
*handle_cachep
;
257 struct kmem_cache
*zspage_cachep
;
259 atomic_long_t pages_allocated
;
261 struct zs_pool_stats stats
;
263 /* Compact classes */
264 struct shrinker shrinker
;
266 #ifdef CONFIG_ZSMALLOC_STAT
267 struct dentry
*stat_dentry
;
269 #ifdef CONFIG_COMPACTION
271 struct work_struct free_work
;
272 /* A wait queue for when migration races with async_free_zspage() */
273 struct wait_queue_head migration_wait
;
274 atomic_long_t isolated_pages
;
281 unsigned int fullness
:FULLNESS_BITS
;
282 unsigned int class:CLASS_BITS
+ 1;
283 unsigned int isolated
:ISOLATED_BITS
;
284 unsigned int magic
:MAGIC_VAL_BITS
;
287 unsigned int freeobj
;
288 struct page
*first_page
;
289 struct list_head list
; /* fullness list */
290 #ifdef CONFIG_COMPACTION
295 struct mapping_area
{
296 char *vm_buf
; /* copy buffer for objects that span pages */
297 char *vm_addr
; /* address of kmap_atomic()'ed pages */
298 enum zs_mapmode vm_mm
; /* mapping mode */
301 #ifdef CONFIG_COMPACTION
302 static int zs_register_migration(struct zs_pool
*pool
);
303 static void zs_unregister_migration(struct zs_pool
*pool
);
304 static void migrate_lock_init(struct zspage
*zspage
);
305 static void migrate_read_lock(struct zspage
*zspage
);
306 static void migrate_read_unlock(struct zspage
*zspage
);
307 static void kick_deferred_free(struct zs_pool
*pool
);
308 static void init_deferred_free(struct zs_pool
*pool
);
309 static void SetZsPageMovable(struct zs_pool
*pool
, struct zspage
*zspage
);
311 static int zsmalloc_mount(void) { return 0; }
312 static void zsmalloc_unmount(void) {}
313 static int zs_register_migration(struct zs_pool
*pool
) { return 0; }
314 static void zs_unregister_migration(struct zs_pool
*pool
) {}
315 static void migrate_lock_init(struct zspage
*zspage
) {}
316 static void migrate_read_lock(struct zspage
*zspage
) {}
317 static void migrate_read_unlock(struct zspage
*zspage
) {}
318 static void kick_deferred_free(struct zs_pool
*pool
) {}
319 static void init_deferred_free(struct zs_pool
*pool
) {}
320 static void SetZsPageMovable(struct zs_pool
*pool
, struct zspage
*zspage
) {}
323 static int create_cache(struct zs_pool
*pool
)
325 pool
->handle_cachep
= kmem_cache_create("zs_handle", ZS_HANDLE_SIZE
,
327 if (!pool
->handle_cachep
)
330 pool
->zspage_cachep
= kmem_cache_create("zspage", sizeof(struct zspage
),
332 if (!pool
->zspage_cachep
) {
333 kmem_cache_destroy(pool
->handle_cachep
);
334 pool
->handle_cachep
= NULL
;
341 static void destroy_cache(struct zs_pool
*pool
)
343 kmem_cache_destroy(pool
->handle_cachep
);
344 kmem_cache_destroy(pool
->zspage_cachep
);
347 static unsigned long cache_alloc_handle(struct zs_pool
*pool
, gfp_t gfp
)
349 return (unsigned long)kmem_cache_alloc(pool
->handle_cachep
,
350 gfp
& ~(__GFP_HIGHMEM
|__GFP_MOVABLE
));
353 static void cache_free_handle(struct zs_pool
*pool
, unsigned long handle
)
355 kmem_cache_free(pool
->handle_cachep
, (void *)handle
);
358 static struct zspage
*cache_alloc_zspage(struct zs_pool
*pool
, gfp_t flags
)
360 return kmem_cache_zalloc(pool
->zspage_cachep
,
361 flags
& ~(__GFP_HIGHMEM
|__GFP_MOVABLE
));
364 static void cache_free_zspage(struct zs_pool
*pool
, struct zspage
*zspage
)
366 kmem_cache_free(pool
->zspage_cachep
, zspage
);
369 static void record_obj(unsigned long handle
, unsigned long obj
)
372 * lsb of @obj represents handle lock while other bits
373 * represent object value the handle is pointing so
374 * updating shouldn't do store tearing.
376 WRITE_ONCE(*(unsigned long *)handle
, obj
);
383 static void *zs_zpool_create(const char *name
, gfp_t gfp
,
384 const struct zpool_ops
*zpool_ops
,
388 * Ignore global gfp flags: zs_malloc() may be invoked from
389 * different contexts and its caller must provide a valid
392 return zs_create_pool(name
);
395 static void zs_zpool_destroy(void *pool
)
397 zs_destroy_pool(pool
);
400 static int zs_zpool_malloc(void *pool
, size_t size
, gfp_t gfp
,
401 unsigned long *handle
)
403 *handle
= zs_malloc(pool
, size
, gfp
);
404 return *handle
? 0 : -1;
406 static void zs_zpool_free(void *pool
, unsigned long handle
)
408 zs_free(pool
, handle
);
411 static void *zs_zpool_map(void *pool
, unsigned long handle
,
412 enum zpool_mapmode mm
)
414 enum zs_mapmode zs_mm
;
429 return zs_map_object(pool
, handle
, zs_mm
);
431 static void zs_zpool_unmap(void *pool
, unsigned long handle
)
433 zs_unmap_object(pool
, handle
);
436 static u64
zs_zpool_total_size(void *pool
)
438 return zs_get_total_pages(pool
) << PAGE_SHIFT
;
441 static struct zpool_driver zs_zpool_driver
= {
443 .owner
= THIS_MODULE
,
444 .create
= zs_zpool_create
,
445 .destroy
= zs_zpool_destroy
,
446 .malloc_support_movable
= true,
447 .malloc
= zs_zpool_malloc
,
448 .free
= zs_zpool_free
,
450 .unmap
= zs_zpool_unmap
,
451 .total_size
= zs_zpool_total_size
,
454 MODULE_ALIAS("zpool-zsmalloc");
455 #endif /* CONFIG_ZPOOL */
457 /* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
458 static DEFINE_PER_CPU(struct mapping_area
, zs_map_area
);
460 static bool is_zspage_isolated(struct zspage
*zspage
)
462 return zspage
->isolated
;
465 static __maybe_unused
int is_first_page(struct page
*page
)
467 return PagePrivate(page
);
470 /* Protected by class->lock */
471 static inline int get_zspage_inuse(struct zspage
*zspage
)
473 return zspage
->inuse
;
477 static inline void mod_zspage_inuse(struct zspage
*zspage
, int val
)
479 zspage
->inuse
+= val
;
482 static inline struct page
*get_first_page(struct zspage
*zspage
)
484 struct page
*first_page
= zspage
->first_page
;
486 VM_BUG_ON_PAGE(!is_first_page(first_page
), first_page
);
490 static inline int get_first_obj_offset(struct page
*page
)
495 static inline void set_first_obj_offset(struct page
*page
, int offset
)
497 page
->units
= offset
;
500 static inline unsigned int get_freeobj(struct zspage
*zspage
)
502 return zspage
->freeobj
;
505 static inline void set_freeobj(struct zspage
*zspage
, unsigned int obj
)
507 zspage
->freeobj
= obj
;
510 static void get_zspage_mapping(struct zspage
*zspage
,
511 unsigned int *class_idx
,
512 enum fullness_group
*fullness
)
514 BUG_ON(zspage
->magic
!= ZSPAGE_MAGIC
);
516 *fullness
= zspage
->fullness
;
517 *class_idx
= zspage
->class;
520 static void set_zspage_mapping(struct zspage
*zspage
,
521 unsigned int class_idx
,
522 enum fullness_group fullness
)
524 zspage
->class = class_idx
;
525 zspage
->fullness
= fullness
;
529 * zsmalloc divides the pool into various size classes where each
530 * class maintains a list of zspages where each zspage is divided
531 * into equal sized chunks. Each allocation falls into one of these
532 * classes depending on its size. This function returns index of the
533 * size class which has chunk size big enough to hold the given size.
535 static int get_size_class_index(int size
)
539 if (likely(size
> ZS_MIN_ALLOC_SIZE
))
540 idx
= DIV_ROUND_UP(size
- ZS_MIN_ALLOC_SIZE
,
541 ZS_SIZE_CLASS_DELTA
);
543 return min_t(int, ZS_SIZE_CLASSES
- 1, idx
);
546 /* type can be of enum type zs_stat_type or fullness_group */
547 static inline void zs_stat_inc(struct size_class
*class,
548 int type
, unsigned long cnt
)
550 class->stats
.objs
[type
] += cnt
;
553 /* type can be of enum type zs_stat_type or fullness_group */
554 static inline void zs_stat_dec(struct size_class
*class,
555 int type
, unsigned long cnt
)
557 class->stats
.objs
[type
] -= cnt
;
560 /* type can be of enum type zs_stat_type or fullness_group */
561 static inline unsigned long zs_stat_get(struct size_class
*class,
564 return class->stats
.objs
[type
];
567 #ifdef CONFIG_ZSMALLOC_STAT
569 static void __init
zs_stat_init(void)
571 if (!debugfs_initialized()) {
572 pr_warn("debugfs not available, stat dir not created\n");
576 zs_stat_root
= debugfs_create_dir("zsmalloc", NULL
);
579 static void __exit
zs_stat_exit(void)
581 debugfs_remove_recursive(zs_stat_root
);
584 static unsigned long zs_can_compact(struct size_class
*class);
586 static int zs_stats_size_show(struct seq_file
*s
, void *v
)
589 struct zs_pool
*pool
= s
->private;
590 struct size_class
*class;
592 unsigned long class_almost_full
, class_almost_empty
;
593 unsigned long obj_allocated
, obj_used
, pages_used
, freeable
;
594 unsigned long total_class_almost_full
= 0, total_class_almost_empty
= 0;
595 unsigned long total_objs
= 0, total_used_objs
= 0, total_pages
= 0;
596 unsigned long total_freeable
= 0;
598 seq_printf(s
, " %5s %5s %11s %12s %13s %10s %10s %16s %8s\n",
599 "class", "size", "almost_full", "almost_empty",
600 "obj_allocated", "obj_used", "pages_used",
601 "pages_per_zspage", "freeable");
603 for (i
= 0; i
< ZS_SIZE_CLASSES
; i
++) {
604 class = pool
->size_class
[i
];
606 if (class->index
!= i
)
609 spin_lock(&class->lock
);
610 class_almost_full
= zs_stat_get(class, CLASS_ALMOST_FULL
);
611 class_almost_empty
= zs_stat_get(class, CLASS_ALMOST_EMPTY
);
612 obj_allocated
= zs_stat_get(class, OBJ_ALLOCATED
);
613 obj_used
= zs_stat_get(class, OBJ_USED
);
614 freeable
= zs_can_compact(class);
615 spin_unlock(&class->lock
);
617 objs_per_zspage
= class->objs_per_zspage
;
618 pages_used
= obj_allocated
/ objs_per_zspage
*
619 class->pages_per_zspage
;
621 seq_printf(s
, " %5u %5u %11lu %12lu %13lu"
622 " %10lu %10lu %16d %8lu\n",
623 i
, class->size
, class_almost_full
, class_almost_empty
,
624 obj_allocated
, obj_used
, pages_used
,
625 class->pages_per_zspage
, freeable
);
627 total_class_almost_full
+= class_almost_full
;
628 total_class_almost_empty
+= class_almost_empty
;
629 total_objs
+= obj_allocated
;
630 total_used_objs
+= obj_used
;
631 total_pages
+= pages_used
;
632 total_freeable
+= freeable
;
636 seq_printf(s
, " %5s %5s %11lu %12lu %13lu %10lu %10lu %16s %8lu\n",
637 "Total", "", total_class_almost_full
,
638 total_class_almost_empty
, total_objs
,
639 total_used_objs
, total_pages
, "", total_freeable
);
643 DEFINE_SHOW_ATTRIBUTE(zs_stats_size
);
645 static void zs_pool_stat_create(struct zs_pool
*pool
, const char *name
)
648 pr_warn("no root stat dir, not creating <%s> stat dir\n", name
);
652 pool
->stat_dentry
= debugfs_create_dir(name
, zs_stat_root
);
654 debugfs_create_file("classes", S_IFREG
| 0444, pool
->stat_dentry
, pool
,
655 &zs_stats_size_fops
);
658 static void zs_pool_stat_destroy(struct zs_pool
*pool
)
660 debugfs_remove_recursive(pool
->stat_dentry
);
663 #else /* CONFIG_ZSMALLOC_STAT */
664 static void __init
zs_stat_init(void)
668 static void __exit
zs_stat_exit(void)
672 static inline void zs_pool_stat_create(struct zs_pool
*pool
, const char *name
)
676 static inline void zs_pool_stat_destroy(struct zs_pool
*pool
)
683 * For each size class, zspages are divided into different groups
684 * depending on how "full" they are. This was done so that we could
685 * easily find empty or nearly empty zspages when we try to shrink
686 * the pool (not yet implemented). This function returns fullness
687 * status of the given page.
689 static enum fullness_group
get_fullness_group(struct size_class
*class,
690 struct zspage
*zspage
)
692 int inuse
, objs_per_zspage
;
693 enum fullness_group fg
;
695 inuse
= get_zspage_inuse(zspage
);
696 objs_per_zspage
= class->objs_per_zspage
;
700 else if (inuse
== objs_per_zspage
)
702 else if (inuse
<= 3 * objs_per_zspage
/ fullness_threshold_frac
)
703 fg
= ZS_ALMOST_EMPTY
;
711 * Each size class maintains various freelists and zspages are assigned
712 * to one of these freelists based on the number of live objects they
713 * have. This functions inserts the given zspage into the freelist
714 * identified by <class, fullness_group>.
716 static void insert_zspage(struct size_class
*class,
717 struct zspage
*zspage
,
718 enum fullness_group fullness
)
722 zs_stat_inc(class, fullness
, 1);
723 head
= list_first_entry_or_null(&class->fullness_list
[fullness
],
724 struct zspage
, list
);
726 * We want to see more ZS_FULL pages and less almost empty/full.
727 * Put pages with higher ->inuse first.
729 if (head
&& get_zspage_inuse(zspage
) < get_zspage_inuse(head
))
730 list_add(&zspage
->list
, &head
->list
);
732 list_add(&zspage
->list
, &class->fullness_list
[fullness
]);
736 * This function removes the given zspage from the freelist identified
737 * by <class, fullness_group>.
739 static void remove_zspage(struct size_class
*class,
740 struct zspage
*zspage
,
741 enum fullness_group fullness
)
743 VM_BUG_ON(list_empty(&class->fullness_list
[fullness
]));
744 VM_BUG_ON(is_zspage_isolated(zspage
));
746 list_del_init(&zspage
->list
);
747 zs_stat_dec(class, fullness
, 1);
751 * Each size class maintains zspages in different fullness groups depending
752 * on the number of live objects they contain. When allocating or freeing
753 * objects, the fullness status of the page can change, say, from ALMOST_FULL
754 * to ALMOST_EMPTY when freeing an object. This function checks if such
755 * a status change has occurred for the given page and accordingly moves the
756 * page from the freelist of the old fullness group to that of the new
759 static enum fullness_group
fix_fullness_group(struct size_class
*class,
760 struct zspage
*zspage
)
763 enum fullness_group currfg
, newfg
;
765 get_zspage_mapping(zspage
, &class_idx
, &currfg
);
766 newfg
= get_fullness_group(class, zspage
);
770 if (!is_zspage_isolated(zspage
)) {
771 remove_zspage(class, zspage
, currfg
);
772 insert_zspage(class, zspage
, newfg
);
775 set_zspage_mapping(zspage
, class_idx
, newfg
);
782 * We have to decide on how many pages to link together
783 * to form a zspage for each size class. This is important
784 * to reduce wastage due to unusable space left at end of
785 * each zspage which is given as:
786 * wastage = Zp % class_size
787 * usage = Zp - wastage
788 * where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ...
790 * For example, for size class of 3/8 * PAGE_SIZE, we should
791 * link together 3 PAGE_SIZE sized pages to form a zspage
792 * since then we can perfectly fit in 8 such objects.
794 static int get_pages_per_zspage(int class_size
)
796 int i
, max_usedpc
= 0;
797 /* zspage order which gives maximum used size per KB */
798 int max_usedpc_order
= 1;
800 for (i
= 1; i
<= ZS_MAX_PAGES_PER_ZSPAGE
; i
++) {
804 zspage_size
= i
* PAGE_SIZE
;
805 waste
= zspage_size
% class_size
;
806 usedpc
= (zspage_size
- waste
) * 100 / zspage_size
;
808 if (usedpc
> max_usedpc
) {
810 max_usedpc_order
= i
;
814 return max_usedpc_order
;
817 static struct zspage
*get_zspage(struct page
*page
)
819 struct zspage
*zspage
= (struct zspage
*)page_private(page
);
821 BUG_ON(zspage
->magic
!= ZSPAGE_MAGIC
);
825 static struct page
*get_next_page(struct page
*page
)
827 if (unlikely(PageHugeObject(page
)))
830 return page
->freelist
;
834 * obj_to_location - get (<page>, <obj_idx>) from encoded object value
835 * @obj: the encoded object value
836 * @page: page object resides in zspage
837 * @obj_idx: object index
839 static void obj_to_location(unsigned long obj
, struct page
**page
,
840 unsigned int *obj_idx
)
842 obj
>>= OBJ_TAG_BITS
;
843 *page
= pfn_to_page(obj
>> OBJ_INDEX_BITS
);
844 *obj_idx
= (obj
& OBJ_INDEX_MASK
);
848 * location_to_obj - get obj value encoded from (<page>, <obj_idx>)
849 * @page: page object resides in zspage
850 * @obj_idx: object index
852 static unsigned long location_to_obj(struct page
*page
, unsigned int obj_idx
)
856 obj
= page_to_pfn(page
) << OBJ_INDEX_BITS
;
857 obj
|= obj_idx
& OBJ_INDEX_MASK
;
858 obj
<<= OBJ_TAG_BITS
;
863 static unsigned long handle_to_obj(unsigned long handle
)
865 return *(unsigned long *)handle
;
868 static unsigned long obj_to_head(struct page
*page
, void *obj
)
870 if (unlikely(PageHugeObject(page
))) {
871 VM_BUG_ON_PAGE(!is_first_page(page
), page
);
874 return *(unsigned long *)obj
;
877 static inline int testpin_tag(unsigned long handle
)
879 return bit_spin_is_locked(HANDLE_PIN_BIT
, (unsigned long *)handle
);
882 static inline int trypin_tag(unsigned long handle
)
884 return bit_spin_trylock(HANDLE_PIN_BIT
, (unsigned long *)handle
);
887 static void pin_tag(unsigned long handle
) __acquires(bitlock
)
889 bit_spin_lock(HANDLE_PIN_BIT
, (unsigned long *)handle
);
892 static void unpin_tag(unsigned long handle
) __releases(bitlock
)
894 bit_spin_unlock(HANDLE_PIN_BIT
, (unsigned long *)handle
);
897 static void reset_page(struct page
*page
)
899 __ClearPageMovable(page
);
900 ClearPagePrivate(page
);
901 set_page_private(page
, 0);
902 page_mapcount_reset(page
);
903 ClearPageHugeObject(page
);
904 page
->freelist
= NULL
;
907 static int trylock_zspage(struct zspage
*zspage
)
909 struct page
*cursor
, *fail
;
911 for (cursor
= get_first_page(zspage
); cursor
!= NULL
; cursor
=
912 get_next_page(cursor
)) {
913 if (!trylock_page(cursor
)) {
921 for (cursor
= get_first_page(zspage
); cursor
!= fail
; cursor
=
922 get_next_page(cursor
))
928 static void __free_zspage(struct zs_pool
*pool
, struct size_class
*class,
929 struct zspage
*zspage
)
931 struct page
*page
, *next
;
932 enum fullness_group fg
;
933 unsigned int class_idx
;
935 get_zspage_mapping(zspage
, &class_idx
, &fg
);
937 assert_spin_locked(&class->lock
);
939 VM_BUG_ON(get_zspage_inuse(zspage
));
940 VM_BUG_ON(fg
!= ZS_EMPTY
);
942 next
= page
= get_first_page(zspage
);
944 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
945 next
= get_next_page(page
);
948 dec_zone_page_state(page
, NR_ZSPAGES
);
951 } while (page
!= NULL
);
953 cache_free_zspage(pool
, zspage
);
955 zs_stat_dec(class, OBJ_ALLOCATED
, class->objs_per_zspage
);
956 atomic_long_sub(class->pages_per_zspage
,
957 &pool
->pages_allocated
);
960 static void free_zspage(struct zs_pool
*pool
, struct size_class
*class,
961 struct zspage
*zspage
)
963 VM_BUG_ON(get_zspage_inuse(zspage
));
964 VM_BUG_ON(list_empty(&zspage
->list
));
966 if (!trylock_zspage(zspage
)) {
967 kick_deferred_free(pool
);
971 remove_zspage(class, zspage
, ZS_EMPTY
);
972 __free_zspage(pool
, class, zspage
);
975 /* Initialize a newly allocated zspage */
976 static void init_zspage(struct size_class
*class, struct zspage
*zspage
)
978 unsigned int freeobj
= 1;
979 unsigned long off
= 0;
980 struct page
*page
= get_first_page(zspage
);
983 struct page
*next_page
;
984 struct link_free
*link
;
987 set_first_obj_offset(page
, off
);
989 vaddr
= kmap_atomic(page
);
990 link
= (struct link_free
*)vaddr
+ off
/ sizeof(*link
);
992 while ((off
+= class->size
) < PAGE_SIZE
) {
993 link
->next
= freeobj
++ << OBJ_TAG_BITS
;
994 link
+= class->size
/ sizeof(*link
);
998 * We now come to the last (full or partial) object on this
999 * page, which must point to the first object on the next
1002 next_page
= get_next_page(page
);
1004 link
->next
= freeobj
++ << OBJ_TAG_BITS
;
1007 * Reset OBJ_TAG_BITS bit to last link to tell
1008 * whether it's allocated object or not.
1010 link
->next
= -1UL << OBJ_TAG_BITS
;
1012 kunmap_atomic(vaddr
);
1017 set_freeobj(zspage
, 0);
1020 static void create_page_chain(struct size_class
*class, struct zspage
*zspage
,
1021 struct page
*pages
[])
1025 struct page
*prev_page
= NULL
;
1026 int nr_pages
= class->pages_per_zspage
;
1029 * Allocate individual pages and link them together as:
1030 * 1. all pages are linked together using page->freelist
1031 * 2. each sub-page point to zspage using page->private
1033 * we set PG_private to identify the first page (i.e. no other sub-page
1034 * has this flag set).
1036 for (i
= 0; i
< nr_pages
; i
++) {
1038 set_page_private(page
, (unsigned long)zspage
);
1039 page
->freelist
= NULL
;
1041 zspage
->first_page
= page
;
1042 SetPagePrivate(page
);
1043 if (unlikely(class->objs_per_zspage
== 1 &&
1044 class->pages_per_zspage
== 1))
1045 SetPageHugeObject(page
);
1047 prev_page
->freelist
= page
;
1054 * Allocate a zspage for the given size class
1056 static struct zspage
*alloc_zspage(struct zs_pool
*pool
,
1057 struct size_class
*class,
1061 struct page
*pages
[ZS_MAX_PAGES_PER_ZSPAGE
];
1062 struct zspage
*zspage
= cache_alloc_zspage(pool
, gfp
);
1067 zspage
->magic
= ZSPAGE_MAGIC
;
1068 migrate_lock_init(zspage
);
1070 for (i
= 0; i
< class->pages_per_zspage
; i
++) {
1073 page
= alloc_page(gfp
);
1076 dec_zone_page_state(pages
[i
], NR_ZSPAGES
);
1077 __free_page(pages
[i
]);
1079 cache_free_zspage(pool
, zspage
);
1083 inc_zone_page_state(page
, NR_ZSPAGES
);
1087 create_page_chain(class, zspage
, pages
);
1088 init_zspage(class, zspage
);
1093 static struct zspage
*find_get_zspage(struct size_class
*class)
1096 struct zspage
*zspage
;
1098 for (i
= ZS_ALMOST_FULL
; i
>= ZS_EMPTY
; i
--) {
1099 zspage
= list_first_entry_or_null(&class->fullness_list
[i
],
1100 struct zspage
, list
);
1108 static inline int __zs_cpu_up(struct mapping_area
*area
)
1111 * Make sure we don't leak memory if a cpu UP notification
1112 * and zs_init() race and both call zs_cpu_up() on the same cpu
1116 area
->vm_buf
= kmalloc(ZS_MAX_ALLOC_SIZE
, GFP_KERNEL
);
1122 static inline void __zs_cpu_down(struct mapping_area
*area
)
1124 kfree(area
->vm_buf
);
1125 area
->vm_buf
= NULL
;
1128 static void *__zs_map_object(struct mapping_area
*area
,
1129 struct page
*pages
[2], int off
, int size
)
1133 char *buf
= area
->vm_buf
;
1135 /* disable page faults to match kmap_atomic() return conditions */
1136 pagefault_disable();
1138 /* no read fastpath */
1139 if (area
->vm_mm
== ZS_MM_WO
)
1142 sizes
[0] = PAGE_SIZE
- off
;
1143 sizes
[1] = size
- sizes
[0];
1145 /* copy object to per-cpu buffer */
1146 addr
= kmap_atomic(pages
[0]);
1147 memcpy(buf
, addr
+ off
, sizes
[0]);
1148 kunmap_atomic(addr
);
1149 addr
= kmap_atomic(pages
[1]);
1150 memcpy(buf
+ sizes
[0], addr
, sizes
[1]);
1151 kunmap_atomic(addr
);
1153 return area
->vm_buf
;
1156 static void __zs_unmap_object(struct mapping_area
*area
,
1157 struct page
*pages
[2], int off
, int size
)
1163 /* no write fastpath */
1164 if (area
->vm_mm
== ZS_MM_RO
)
1168 buf
= buf
+ ZS_HANDLE_SIZE
;
1169 size
-= ZS_HANDLE_SIZE
;
1170 off
+= ZS_HANDLE_SIZE
;
1172 sizes
[0] = PAGE_SIZE
- off
;
1173 sizes
[1] = size
- sizes
[0];
1175 /* copy per-cpu buffer to object */
1176 addr
= kmap_atomic(pages
[0]);
1177 memcpy(addr
+ off
, buf
, sizes
[0]);
1178 kunmap_atomic(addr
);
1179 addr
= kmap_atomic(pages
[1]);
1180 memcpy(addr
, buf
+ sizes
[0], sizes
[1]);
1181 kunmap_atomic(addr
);
1184 /* enable page faults to match kunmap_atomic() return conditions */
1188 static int zs_cpu_prepare(unsigned int cpu
)
1190 struct mapping_area
*area
;
1192 area
= &per_cpu(zs_map_area
, cpu
);
1193 return __zs_cpu_up(area
);
1196 static int zs_cpu_dead(unsigned int cpu
)
1198 struct mapping_area
*area
;
1200 area
= &per_cpu(zs_map_area
, cpu
);
1201 __zs_cpu_down(area
);
1205 static bool can_merge(struct size_class
*prev
, int pages_per_zspage
,
1206 int objs_per_zspage
)
1208 if (prev
->pages_per_zspage
== pages_per_zspage
&&
1209 prev
->objs_per_zspage
== objs_per_zspage
)
1215 static bool zspage_full(struct size_class
*class, struct zspage
*zspage
)
1217 return get_zspage_inuse(zspage
) == class->objs_per_zspage
;
1220 unsigned long zs_get_total_pages(struct zs_pool
*pool
)
1222 return atomic_long_read(&pool
->pages_allocated
);
1224 EXPORT_SYMBOL_GPL(zs_get_total_pages
);
1227 * zs_map_object - get address of allocated object from handle.
1228 * @pool: pool from which the object was allocated
1229 * @handle: handle returned from zs_malloc
1230 * @mm: mapping mode to use
1232 * Before using an object allocated from zs_malloc, it must be mapped using
1233 * this function. When done with the object, it must be unmapped using
1236 * Only one object can be mapped per cpu at a time. There is no protection
1237 * against nested mappings.
1239 * This function returns with preemption and page faults disabled.
1241 void *zs_map_object(struct zs_pool
*pool
, unsigned long handle
,
1244 struct zspage
*zspage
;
1246 unsigned long obj
, off
;
1247 unsigned int obj_idx
;
1249 unsigned int class_idx
;
1250 enum fullness_group fg
;
1251 struct size_class
*class;
1252 struct mapping_area
*area
;
1253 struct page
*pages
[2];
1257 * Because we use per-cpu mapping areas shared among the
1258 * pools/users, we can't allow mapping in interrupt context
1259 * because it can corrupt another users mappings.
1261 BUG_ON(in_interrupt());
1263 /* From now on, migration cannot move the object */
1266 obj
= handle_to_obj(handle
);
1267 obj_to_location(obj
, &page
, &obj_idx
);
1268 zspage
= get_zspage(page
);
1270 /* migration cannot move any subpage in this zspage */
1271 migrate_read_lock(zspage
);
1273 get_zspage_mapping(zspage
, &class_idx
, &fg
);
1274 class = pool
->size_class
[class_idx
];
1275 off
= (class->size
* obj_idx
) & ~PAGE_MASK
;
1277 area
= &get_cpu_var(zs_map_area
);
1279 if (off
+ class->size
<= PAGE_SIZE
) {
1280 /* this object is contained entirely within a page */
1281 area
->vm_addr
= kmap_atomic(page
);
1282 ret
= area
->vm_addr
+ off
;
1286 /* this object spans two pages */
1288 pages
[1] = get_next_page(page
);
1291 ret
= __zs_map_object(area
, pages
, off
, class->size
);
1293 if (likely(!PageHugeObject(page
)))
1294 ret
+= ZS_HANDLE_SIZE
;
1298 EXPORT_SYMBOL_GPL(zs_map_object
);
1300 void zs_unmap_object(struct zs_pool
*pool
, unsigned long handle
)
1302 struct zspage
*zspage
;
1304 unsigned long obj
, off
;
1305 unsigned int obj_idx
;
1307 unsigned int class_idx
;
1308 enum fullness_group fg
;
1309 struct size_class
*class;
1310 struct mapping_area
*area
;
1312 obj
= handle_to_obj(handle
);
1313 obj_to_location(obj
, &page
, &obj_idx
);
1314 zspage
= get_zspage(page
);
1315 get_zspage_mapping(zspage
, &class_idx
, &fg
);
1316 class = pool
->size_class
[class_idx
];
1317 off
= (class->size
* obj_idx
) & ~PAGE_MASK
;
1319 area
= this_cpu_ptr(&zs_map_area
);
1320 if (off
+ class->size
<= PAGE_SIZE
)
1321 kunmap_atomic(area
->vm_addr
);
1323 struct page
*pages
[2];
1326 pages
[1] = get_next_page(page
);
1329 __zs_unmap_object(area
, pages
, off
, class->size
);
1331 put_cpu_var(zs_map_area
);
1333 migrate_read_unlock(zspage
);
1336 EXPORT_SYMBOL_GPL(zs_unmap_object
);
1339 * zs_huge_class_size() - Returns the size (in bytes) of the first huge
1340 * zsmalloc &size_class.
1341 * @pool: zsmalloc pool to use
1343 * The function returns the size of the first huge class - any object of equal
1344 * or bigger size will be stored in zspage consisting of a single physical
1347 * Context: Any context.
1349 * Return: the size (in bytes) of the first huge zsmalloc &size_class.
1351 size_t zs_huge_class_size(struct zs_pool
*pool
)
1353 return huge_class_size
;
1355 EXPORT_SYMBOL_GPL(zs_huge_class_size
);
1357 static unsigned long obj_malloc(struct size_class
*class,
1358 struct zspage
*zspage
, unsigned long handle
)
1360 int i
, nr_page
, offset
;
1362 struct link_free
*link
;
1364 struct page
*m_page
;
1365 unsigned long m_offset
;
1368 handle
|= OBJ_ALLOCATED_TAG
;
1369 obj
= get_freeobj(zspage
);
1371 offset
= obj
* class->size
;
1372 nr_page
= offset
>> PAGE_SHIFT
;
1373 m_offset
= offset
& ~PAGE_MASK
;
1374 m_page
= get_first_page(zspage
);
1376 for (i
= 0; i
< nr_page
; i
++)
1377 m_page
= get_next_page(m_page
);
1379 vaddr
= kmap_atomic(m_page
);
1380 link
= (struct link_free
*)vaddr
+ m_offset
/ sizeof(*link
);
1381 set_freeobj(zspage
, link
->next
>> OBJ_TAG_BITS
);
1382 if (likely(!PageHugeObject(m_page
)))
1383 /* record handle in the header of allocated chunk */
1384 link
->handle
= handle
;
1386 /* record handle to page->index */
1387 zspage
->first_page
->index
= handle
;
1389 kunmap_atomic(vaddr
);
1390 mod_zspage_inuse(zspage
, 1);
1391 zs_stat_inc(class, OBJ_USED
, 1);
1393 obj
= location_to_obj(m_page
, obj
);
1400 * zs_malloc - Allocate block of given size from pool.
1401 * @pool: pool to allocate from
1402 * @size: size of block to allocate
1403 * @gfp: gfp flags when allocating object
1405 * On success, handle to the allocated object is returned,
1407 * Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
1409 unsigned long zs_malloc(struct zs_pool
*pool
, size_t size
, gfp_t gfp
)
1411 unsigned long handle
, obj
;
1412 struct size_class
*class;
1413 enum fullness_group newfg
;
1414 struct zspage
*zspage
;
1416 if (unlikely(!size
|| size
> ZS_MAX_ALLOC_SIZE
))
1419 handle
= cache_alloc_handle(pool
, gfp
);
1423 /* extra space in chunk to keep the handle */
1424 size
+= ZS_HANDLE_SIZE
;
1425 class = pool
->size_class
[get_size_class_index(size
)];
1427 spin_lock(&class->lock
);
1428 zspage
= find_get_zspage(class);
1429 if (likely(zspage
)) {
1430 obj
= obj_malloc(class, zspage
, handle
);
1431 /* Now move the zspage to another fullness group, if required */
1432 fix_fullness_group(class, zspage
);
1433 record_obj(handle
, obj
);
1434 spin_unlock(&class->lock
);
1439 spin_unlock(&class->lock
);
1441 zspage
= alloc_zspage(pool
, class, gfp
);
1443 cache_free_handle(pool
, handle
);
1447 spin_lock(&class->lock
);
1448 obj
= obj_malloc(class, zspage
, handle
);
1449 newfg
= get_fullness_group(class, zspage
);
1450 insert_zspage(class, zspage
, newfg
);
1451 set_zspage_mapping(zspage
, class->index
, newfg
);
1452 record_obj(handle
, obj
);
1453 atomic_long_add(class->pages_per_zspage
,
1454 &pool
->pages_allocated
);
1455 zs_stat_inc(class, OBJ_ALLOCATED
, class->objs_per_zspage
);
1457 /* We completely set up zspage so mark them as movable */
1458 SetZsPageMovable(pool
, zspage
);
1459 spin_unlock(&class->lock
);
1463 EXPORT_SYMBOL_GPL(zs_malloc
);
1465 static void obj_free(struct size_class
*class, unsigned long obj
)
1467 struct link_free
*link
;
1468 struct zspage
*zspage
;
1469 struct page
*f_page
;
1470 unsigned long f_offset
;
1471 unsigned int f_objidx
;
1474 obj_to_location(obj
, &f_page
, &f_objidx
);
1475 f_offset
= (class->size
* f_objidx
) & ~PAGE_MASK
;
1476 zspage
= get_zspage(f_page
);
1478 vaddr
= kmap_atomic(f_page
);
1480 /* Insert this object in containing zspage's freelist */
1481 link
= (struct link_free
*)(vaddr
+ f_offset
);
1482 link
->next
= get_freeobj(zspage
) << OBJ_TAG_BITS
;
1483 kunmap_atomic(vaddr
);
1484 set_freeobj(zspage
, f_objidx
);
1485 mod_zspage_inuse(zspage
, -1);
1486 zs_stat_dec(class, OBJ_USED
, 1);
1489 void zs_free(struct zs_pool
*pool
, unsigned long handle
)
1491 struct zspage
*zspage
;
1492 struct page
*f_page
;
1494 unsigned int f_objidx
;
1496 struct size_class
*class;
1497 enum fullness_group fullness
;
1500 if (unlikely(!handle
))
1504 obj
= handle_to_obj(handle
);
1505 obj_to_location(obj
, &f_page
, &f_objidx
);
1506 zspage
= get_zspage(f_page
);
1508 migrate_read_lock(zspage
);
1510 get_zspage_mapping(zspage
, &class_idx
, &fullness
);
1511 class = pool
->size_class
[class_idx
];
1513 spin_lock(&class->lock
);
1514 obj_free(class, obj
);
1515 fullness
= fix_fullness_group(class, zspage
);
1516 if (fullness
!= ZS_EMPTY
) {
1517 migrate_read_unlock(zspage
);
1521 isolated
= is_zspage_isolated(zspage
);
1522 migrate_read_unlock(zspage
);
1523 /* If zspage is isolated, zs_page_putback will free the zspage */
1524 if (likely(!isolated
))
1525 free_zspage(pool
, class, zspage
);
1528 spin_unlock(&class->lock
);
1530 cache_free_handle(pool
, handle
);
1532 EXPORT_SYMBOL_GPL(zs_free
);
1534 static void zs_object_copy(struct size_class
*class, unsigned long dst
,
1537 struct page
*s_page
, *d_page
;
1538 unsigned int s_objidx
, d_objidx
;
1539 unsigned long s_off
, d_off
;
1540 void *s_addr
, *d_addr
;
1541 int s_size
, d_size
, size
;
1544 s_size
= d_size
= class->size
;
1546 obj_to_location(src
, &s_page
, &s_objidx
);
1547 obj_to_location(dst
, &d_page
, &d_objidx
);
1549 s_off
= (class->size
* s_objidx
) & ~PAGE_MASK
;
1550 d_off
= (class->size
* d_objidx
) & ~PAGE_MASK
;
1552 if (s_off
+ class->size
> PAGE_SIZE
)
1553 s_size
= PAGE_SIZE
- s_off
;
1555 if (d_off
+ class->size
> PAGE_SIZE
)
1556 d_size
= PAGE_SIZE
- d_off
;
1558 s_addr
= kmap_atomic(s_page
);
1559 d_addr
= kmap_atomic(d_page
);
1562 size
= min(s_size
, d_size
);
1563 memcpy(d_addr
+ d_off
, s_addr
+ s_off
, size
);
1566 if (written
== class->size
)
1574 if (s_off
>= PAGE_SIZE
) {
1575 kunmap_atomic(d_addr
);
1576 kunmap_atomic(s_addr
);
1577 s_page
= get_next_page(s_page
);
1578 s_addr
= kmap_atomic(s_page
);
1579 d_addr
= kmap_atomic(d_page
);
1580 s_size
= class->size
- written
;
1584 if (d_off
>= PAGE_SIZE
) {
1585 kunmap_atomic(d_addr
);
1586 d_page
= get_next_page(d_page
);
1587 d_addr
= kmap_atomic(d_page
);
1588 d_size
= class->size
- written
;
1593 kunmap_atomic(d_addr
);
1594 kunmap_atomic(s_addr
);
1598 * Find alloced object in zspage from index object and
1601 static unsigned long find_alloced_obj(struct size_class
*class,
1602 struct page
*page
, int *obj_idx
)
1606 int index
= *obj_idx
;
1607 unsigned long handle
= 0;
1608 void *addr
= kmap_atomic(page
);
1610 offset
= get_first_obj_offset(page
);
1611 offset
+= class->size
* index
;
1613 while (offset
< PAGE_SIZE
) {
1614 head
= obj_to_head(page
, addr
+ offset
);
1615 if (head
& OBJ_ALLOCATED_TAG
) {
1616 handle
= head
& ~OBJ_ALLOCATED_TAG
;
1617 if (trypin_tag(handle
))
1622 offset
+= class->size
;
1626 kunmap_atomic(addr
);
1633 struct zs_compact_control
{
1634 /* Source spage for migration which could be a subpage of zspage */
1635 struct page
*s_page
;
1636 /* Destination page for migration which should be a first page
1638 struct page
*d_page
;
1639 /* Starting object index within @s_page which used for live object
1640 * in the subpage. */
1644 static int migrate_zspage(struct zs_pool
*pool
, struct size_class
*class,
1645 struct zs_compact_control
*cc
)
1647 unsigned long used_obj
, free_obj
;
1648 unsigned long handle
;
1649 struct page
*s_page
= cc
->s_page
;
1650 struct page
*d_page
= cc
->d_page
;
1651 int obj_idx
= cc
->obj_idx
;
1655 handle
= find_alloced_obj(class, s_page
, &obj_idx
);
1657 s_page
= get_next_page(s_page
);
1664 /* Stop if there is no more space */
1665 if (zspage_full(class, get_zspage(d_page
))) {
1671 used_obj
= handle_to_obj(handle
);
1672 free_obj
= obj_malloc(class, get_zspage(d_page
), handle
);
1673 zs_object_copy(class, free_obj
, used_obj
);
1676 * record_obj updates handle's value to free_obj and it will
1677 * invalidate lock bit(ie, HANDLE_PIN_BIT) of handle, which
1678 * breaks synchronization using pin_tag(e,g, zs_free) so
1679 * let's keep the lock bit.
1681 free_obj
|= BIT(HANDLE_PIN_BIT
);
1682 record_obj(handle
, free_obj
);
1684 obj_free(class, used_obj
);
1687 /* Remember last position in this iteration */
1688 cc
->s_page
= s_page
;
1689 cc
->obj_idx
= obj_idx
;
1694 static struct zspage
*isolate_zspage(struct size_class
*class, bool source
)
1697 struct zspage
*zspage
;
1698 enum fullness_group fg
[2] = {ZS_ALMOST_EMPTY
, ZS_ALMOST_FULL
};
1701 fg
[0] = ZS_ALMOST_FULL
;
1702 fg
[1] = ZS_ALMOST_EMPTY
;
1705 for (i
= 0; i
< 2; i
++) {
1706 zspage
= list_first_entry_or_null(&class->fullness_list
[fg
[i
]],
1707 struct zspage
, list
);
1709 VM_BUG_ON(is_zspage_isolated(zspage
));
1710 remove_zspage(class, zspage
, fg
[i
]);
1719 * putback_zspage - add @zspage into right class's fullness list
1720 * @class: destination class
1721 * @zspage: target page
1723 * Return @zspage's fullness_group
1725 static enum fullness_group
putback_zspage(struct size_class
*class,
1726 struct zspage
*zspage
)
1728 enum fullness_group fullness
;
1730 VM_BUG_ON(is_zspage_isolated(zspage
));
1732 fullness
= get_fullness_group(class, zspage
);
1733 insert_zspage(class, zspage
, fullness
);
1734 set_zspage_mapping(zspage
, class->index
, fullness
);
1739 #ifdef CONFIG_COMPACTION
1741 * To prevent zspage destroy during migration, zspage freeing should
1742 * hold locks of all pages in the zspage.
1744 static void lock_zspage(struct zspage
*zspage
)
1746 struct page
*page
= get_first_page(zspage
);
1750 } while ((page
= get_next_page(page
)) != NULL
);
1753 static int zs_init_fs_context(struct fs_context
*fc
)
1755 return init_pseudo(fc
, ZSMALLOC_MAGIC
) ? 0 : -ENOMEM
;
1758 static struct file_system_type zsmalloc_fs
= {
1760 .init_fs_context
= zs_init_fs_context
,
1761 .kill_sb
= kill_anon_super
,
1764 static int zsmalloc_mount(void)
1768 zsmalloc_mnt
= kern_mount(&zsmalloc_fs
);
1769 if (IS_ERR(zsmalloc_mnt
))
1770 ret
= PTR_ERR(zsmalloc_mnt
);
1775 static void zsmalloc_unmount(void)
1777 kern_unmount(zsmalloc_mnt
);
1780 static void migrate_lock_init(struct zspage
*zspage
)
1782 rwlock_init(&zspage
->lock
);
1785 static void migrate_read_lock(struct zspage
*zspage
) __acquires(&zspage
->lock
)
1787 read_lock(&zspage
->lock
);
1790 static void migrate_read_unlock(struct zspage
*zspage
) __releases(&zspage
->lock
)
1792 read_unlock(&zspage
->lock
);
1795 static void migrate_write_lock(struct zspage
*zspage
)
1797 write_lock(&zspage
->lock
);
1800 static void migrate_write_unlock(struct zspage
*zspage
)
1802 write_unlock(&zspage
->lock
);
1805 /* Number of isolated subpage for *page migration* in this zspage */
1806 static void inc_zspage_isolation(struct zspage
*zspage
)
1811 static void dec_zspage_isolation(struct zspage
*zspage
)
1816 static void putback_zspage_deferred(struct zs_pool
*pool
,
1817 struct size_class
*class,
1818 struct zspage
*zspage
)
1820 enum fullness_group fg
;
1822 fg
= putback_zspage(class, zspage
);
1824 schedule_work(&pool
->free_work
);
1828 static inline void zs_pool_dec_isolated(struct zs_pool
*pool
)
1830 VM_BUG_ON(atomic_long_read(&pool
->isolated_pages
) <= 0);
1831 atomic_long_dec(&pool
->isolated_pages
);
1833 * There's no possibility of racing, since wait_for_isolated_drain()
1834 * checks the isolated count under &class->lock after enqueuing
1835 * on migration_wait.
1837 if (atomic_long_read(&pool
->isolated_pages
) == 0 && pool
->destroying
)
1838 wake_up_all(&pool
->migration_wait
);
1841 static void replace_sub_page(struct size_class
*class, struct zspage
*zspage
,
1842 struct page
*newpage
, struct page
*oldpage
)
1845 struct page
*pages
[ZS_MAX_PAGES_PER_ZSPAGE
] = {NULL
, };
1848 page
= get_first_page(zspage
);
1850 if (page
== oldpage
)
1851 pages
[idx
] = newpage
;
1855 } while ((page
= get_next_page(page
)) != NULL
);
1857 create_page_chain(class, zspage
, pages
);
1858 set_first_obj_offset(newpage
, get_first_obj_offset(oldpage
));
1859 if (unlikely(PageHugeObject(oldpage
)))
1860 newpage
->index
= oldpage
->index
;
1861 __SetPageMovable(newpage
, page_mapping(oldpage
));
1864 static bool zs_page_isolate(struct page
*page
, isolate_mode_t mode
)
1866 struct zs_pool
*pool
;
1867 struct size_class
*class;
1869 enum fullness_group fullness
;
1870 struct zspage
*zspage
;
1871 struct address_space
*mapping
;
1874 * Page is locked so zspage couldn't be destroyed. For detail, look at
1875 * lock_zspage in free_zspage.
1877 VM_BUG_ON_PAGE(!PageMovable(page
), page
);
1878 VM_BUG_ON_PAGE(PageIsolated(page
), page
);
1880 zspage
= get_zspage(page
);
1883 * Without class lock, fullness could be stale while class_idx is okay
1884 * because class_idx is constant unless page is freed so we should get
1885 * fullness again under class lock.
1887 get_zspage_mapping(zspage
, &class_idx
, &fullness
);
1888 mapping
= page_mapping(page
);
1889 pool
= mapping
->private_data
;
1890 class = pool
->size_class
[class_idx
];
1892 spin_lock(&class->lock
);
1893 if (get_zspage_inuse(zspage
) == 0) {
1894 spin_unlock(&class->lock
);
1898 /* zspage is isolated for object migration */
1899 if (list_empty(&zspage
->list
) && !is_zspage_isolated(zspage
)) {
1900 spin_unlock(&class->lock
);
1905 * If this is first time isolation for the zspage, isolate zspage from
1906 * size_class to prevent further object allocation from the zspage.
1908 if (!list_empty(&zspage
->list
) && !is_zspage_isolated(zspage
)) {
1909 get_zspage_mapping(zspage
, &class_idx
, &fullness
);
1910 atomic_long_inc(&pool
->isolated_pages
);
1911 remove_zspage(class, zspage
, fullness
);
1914 inc_zspage_isolation(zspage
);
1915 spin_unlock(&class->lock
);
1920 static int zs_page_migrate(struct address_space
*mapping
, struct page
*newpage
,
1921 struct page
*page
, enum migrate_mode mode
)
1923 struct zs_pool
*pool
;
1924 struct size_class
*class;
1926 enum fullness_group fullness
;
1927 struct zspage
*zspage
;
1929 void *s_addr
, *d_addr
, *addr
;
1931 unsigned long handle
, head
;
1932 unsigned long old_obj
, new_obj
;
1933 unsigned int obj_idx
;
1937 * We cannot support the _NO_COPY case here, because copy needs to
1938 * happen under the zs lock, which does not work with
1939 * MIGRATE_SYNC_NO_COPY workflow.
1941 if (mode
== MIGRATE_SYNC_NO_COPY
)
1944 VM_BUG_ON_PAGE(!PageMovable(page
), page
);
1945 VM_BUG_ON_PAGE(!PageIsolated(page
), page
);
1947 zspage
= get_zspage(page
);
1949 /* Concurrent compactor cannot migrate any subpage in zspage */
1950 migrate_write_lock(zspage
);
1951 get_zspage_mapping(zspage
, &class_idx
, &fullness
);
1952 pool
= mapping
->private_data
;
1953 class = pool
->size_class
[class_idx
];
1954 offset
= get_first_obj_offset(page
);
1956 spin_lock(&class->lock
);
1957 if (!get_zspage_inuse(zspage
)) {
1959 * Set "offset" to end of the page so that every loops
1960 * skips unnecessary object scanning.
1966 s_addr
= kmap_atomic(page
);
1967 while (pos
< PAGE_SIZE
) {
1968 head
= obj_to_head(page
, s_addr
+ pos
);
1969 if (head
& OBJ_ALLOCATED_TAG
) {
1970 handle
= head
& ~OBJ_ALLOCATED_TAG
;
1971 if (!trypin_tag(handle
))
1978 * Here, any user cannot access all objects in the zspage so let's move.
1980 d_addr
= kmap_atomic(newpage
);
1981 memcpy(d_addr
, s_addr
, PAGE_SIZE
);
1982 kunmap_atomic(d_addr
);
1984 for (addr
= s_addr
+ offset
; addr
< s_addr
+ pos
;
1985 addr
+= class->size
) {
1986 head
= obj_to_head(page
, addr
);
1987 if (head
& OBJ_ALLOCATED_TAG
) {
1988 handle
= head
& ~OBJ_ALLOCATED_TAG
;
1989 BUG_ON(!testpin_tag(handle
));
1991 old_obj
= handle_to_obj(handle
);
1992 obj_to_location(old_obj
, &dummy
, &obj_idx
);
1993 new_obj
= (unsigned long)location_to_obj(newpage
,
1995 new_obj
|= BIT(HANDLE_PIN_BIT
);
1996 record_obj(handle
, new_obj
);
2000 replace_sub_page(class, zspage
, newpage
, page
);
2003 dec_zspage_isolation(zspage
);
2006 * Page migration is done so let's putback isolated zspage to
2007 * the list if @page is final isolated subpage in the zspage.
2009 if (!is_zspage_isolated(zspage
)) {
2011 * We cannot race with zs_destroy_pool() here because we wait
2012 * for isolation to hit zero before we start destroying.
2013 * Also, we ensure that everyone can see pool->destroying before
2016 putback_zspage_deferred(pool
, class, zspage
);
2017 zs_pool_dec_isolated(pool
);
2020 if (page_zone(newpage
) != page_zone(page
)) {
2021 dec_zone_page_state(page
, NR_ZSPAGES
);
2022 inc_zone_page_state(newpage
, NR_ZSPAGES
);
2029 ret
= MIGRATEPAGE_SUCCESS
;
2031 for (addr
= s_addr
+ offset
; addr
< s_addr
+ pos
;
2032 addr
+= class->size
) {
2033 head
= obj_to_head(page
, addr
);
2034 if (head
& OBJ_ALLOCATED_TAG
) {
2035 handle
= head
& ~OBJ_ALLOCATED_TAG
;
2036 BUG_ON(!testpin_tag(handle
));
2040 kunmap_atomic(s_addr
);
2041 spin_unlock(&class->lock
);
2042 migrate_write_unlock(zspage
);
2047 static void zs_page_putback(struct page
*page
)
2049 struct zs_pool
*pool
;
2050 struct size_class
*class;
2052 enum fullness_group fg
;
2053 struct address_space
*mapping
;
2054 struct zspage
*zspage
;
2056 VM_BUG_ON_PAGE(!PageMovable(page
), page
);
2057 VM_BUG_ON_PAGE(!PageIsolated(page
), page
);
2059 zspage
= get_zspage(page
);
2060 get_zspage_mapping(zspage
, &class_idx
, &fg
);
2061 mapping
= page_mapping(page
);
2062 pool
= mapping
->private_data
;
2063 class = pool
->size_class
[class_idx
];
2065 spin_lock(&class->lock
);
2066 dec_zspage_isolation(zspage
);
2067 if (!is_zspage_isolated(zspage
)) {
2069 * Due to page_lock, we cannot free zspage immediately
2072 putback_zspage_deferred(pool
, class, zspage
);
2073 zs_pool_dec_isolated(pool
);
2075 spin_unlock(&class->lock
);
2078 static const struct address_space_operations zsmalloc_aops
= {
2079 .isolate_page
= zs_page_isolate
,
2080 .migratepage
= zs_page_migrate
,
2081 .putback_page
= zs_page_putback
,
2084 static int zs_register_migration(struct zs_pool
*pool
)
2086 pool
->inode
= alloc_anon_inode(zsmalloc_mnt
->mnt_sb
);
2087 if (IS_ERR(pool
->inode
)) {
2092 pool
->inode
->i_mapping
->private_data
= pool
;
2093 pool
->inode
->i_mapping
->a_ops
= &zsmalloc_aops
;
2097 static bool pool_isolated_are_drained(struct zs_pool
*pool
)
2099 return atomic_long_read(&pool
->isolated_pages
) == 0;
2102 /* Function for resolving migration */
2103 static void wait_for_isolated_drain(struct zs_pool
*pool
)
2107 * We're in the process of destroying the pool, so there are no
2108 * active allocations. zs_page_isolate() fails for completely free
2109 * zspages, so we need only wait for the zs_pool's isolated
2110 * count to hit zero.
2112 wait_event(pool
->migration_wait
,
2113 pool_isolated_are_drained(pool
));
2116 static void zs_unregister_migration(struct zs_pool
*pool
)
2118 pool
->destroying
= true;
2120 * We need a memory barrier here to ensure global visibility of
2121 * pool->destroying. Thus pool->isolated pages will either be 0 in which
2122 * case we don't care, or it will be > 0 and pool->destroying will
2123 * ensure that we wake up once isolation hits 0.
2126 wait_for_isolated_drain(pool
); /* This can block */
2127 flush_work(&pool
->free_work
);
2132 * Caller should hold page_lock of all pages in the zspage
2133 * In here, we cannot use zspage meta data.
2135 static void async_free_zspage(struct work_struct
*work
)
2138 struct size_class
*class;
2139 unsigned int class_idx
;
2140 enum fullness_group fullness
;
2141 struct zspage
*zspage
, *tmp
;
2142 LIST_HEAD(free_pages
);
2143 struct zs_pool
*pool
= container_of(work
, struct zs_pool
,
2146 for (i
= 0; i
< ZS_SIZE_CLASSES
; i
++) {
2147 class = pool
->size_class
[i
];
2148 if (class->index
!= i
)
2151 spin_lock(&class->lock
);
2152 list_splice_init(&class->fullness_list
[ZS_EMPTY
], &free_pages
);
2153 spin_unlock(&class->lock
);
2157 list_for_each_entry_safe(zspage
, tmp
, &free_pages
, list
) {
2158 list_del(&zspage
->list
);
2159 lock_zspage(zspage
);
2161 get_zspage_mapping(zspage
, &class_idx
, &fullness
);
2162 VM_BUG_ON(fullness
!= ZS_EMPTY
);
2163 class = pool
->size_class
[class_idx
];
2164 spin_lock(&class->lock
);
2165 __free_zspage(pool
, class, zspage
);
2166 spin_unlock(&class->lock
);
2170 static void kick_deferred_free(struct zs_pool
*pool
)
2172 schedule_work(&pool
->free_work
);
2175 static void init_deferred_free(struct zs_pool
*pool
)
2177 INIT_WORK(&pool
->free_work
, async_free_zspage
);
2180 static void SetZsPageMovable(struct zs_pool
*pool
, struct zspage
*zspage
)
2182 struct page
*page
= get_first_page(zspage
);
2185 WARN_ON(!trylock_page(page
));
2186 __SetPageMovable(page
, pool
->inode
->i_mapping
);
2188 } while ((page
= get_next_page(page
)) != NULL
);
2194 * Based on the number of unused allocated objects calculate
2195 * and return the number of pages that we can free.
2197 static unsigned long zs_can_compact(struct size_class
*class)
2199 unsigned long obj_wasted
;
2200 unsigned long obj_allocated
= zs_stat_get(class, OBJ_ALLOCATED
);
2201 unsigned long obj_used
= zs_stat_get(class, OBJ_USED
);
2203 if (obj_allocated
<= obj_used
)
2206 obj_wasted
= obj_allocated
- obj_used
;
2207 obj_wasted
/= class->objs_per_zspage
;
2209 return obj_wasted
* class->pages_per_zspage
;
2212 static unsigned long __zs_compact(struct zs_pool
*pool
,
2213 struct size_class
*class)
2215 struct zs_compact_control cc
;
2216 struct zspage
*src_zspage
;
2217 struct zspage
*dst_zspage
= NULL
;
2218 unsigned long pages_freed
= 0;
2220 spin_lock(&class->lock
);
2221 while ((src_zspage
= isolate_zspage(class, true))) {
2223 if (!zs_can_compact(class))
2227 cc
.s_page
= get_first_page(src_zspage
);
2229 while ((dst_zspage
= isolate_zspage(class, false))) {
2230 cc
.d_page
= get_first_page(dst_zspage
);
2232 * If there is no more space in dst_page, resched
2233 * and see if anyone had allocated another zspage.
2235 if (!migrate_zspage(pool
, class, &cc
))
2238 putback_zspage(class, dst_zspage
);
2241 /* Stop if we couldn't find slot */
2242 if (dst_zspage
== NULL
)
2245 putback_zspage(class, dst_zspage
);
2246 if (putback_zspage(class, src_zspage
) == ZS_EMPTY
) {
2247 free_zspage(pool
, class, src_zspage
);
2248 pages_freed
+= class->pages_per_zspage
;
2250 spin_unlock(&class->lock
);
2252 spin_lock(&class->lock
);
2256 putback_zspage(class, src_zspage
);
2258 spin_unlock(&class->lock
);
2263 unsigned long zs_compact(struct zs_pool
*pool
)
2266 struct size_class
*class;
2267 unsigned long pages_freed
= 0;
2269 for (i
= ZS_SIZE_CLASSES
- 1; i
>= 0; i
--) {
2270 class = pool
->size_class
[i
];
2273 if (class->index
!= i
)
2275 pages_freed
+= __zs_compact(pool
, class);
2277 atomic_long_add(pages_freed
, &pool
->stats
.pages_compacted
);
2281 EXPORT_SYMBOL_GPL(zs_compact
);
2283 void zs_pool_stats(struct zs_pool
*pool
, struct zs_pool_stats
*stats
)
2285 memcpy(stats
, &pool
->stats
, sizeof(struct zs_pool_stats
));
2287 EXPORT_SYMBOL_GPL(zs_pool_stats
);
2289 static unsigned long zs_shrinker_scan(struct shrinker
*shrinker
,
2290 struct shrink_control
*sc
)
2292 unsigned long pages_freed
;
2293 struct zs_pool
*pool
= container_of(shrinker
, struct zs_pool
,
2297 * Compact classes and calculate compaction delta.
2298 * Can run concurrently with a manually triggered
2299 * (by user) compaction.
2301 pages_freed
= zs_compact(pool
);
2303 return pages_freed
? pages_freed
: SHRINK_STOP
;
2306 static unsigned long zs_shrinker_count(struct shrinker
*shrinker
,
2307 struct shrink_control
*sc
)
2310 struct size_class
*class;
2311 unsigned long pages_to_free
= 0;
2312 struct zs_pool
*pool
= container_of(shrinker
, struct zs_pool
,
2315 for (i
= ZS_SIZE_CLASSES
- 1; i
>= 0; i
--) {
2316 class = pool
->size_class
[i
];
2319 if (class->index
!= i
)
2322 pages_to_free
+= zs_can_compact(class);
2325 return pages_to_free
;
2328 static void zs_unregister_shrinker(struct zs_pool
*pool
)
2330 unregister_shrinker(&pool
->shrinker
);
2333 static int zs_register_shrinker(struct zs_pool
*pool
)
2335 pool
->shrinker
.scan_objects
= zs_shrinker_scan
;
2336 pool
->shrinker
.count_objects
= zs_shrinker_count
;
2337 pool
->shrinker
.batch
= 0;
2338 pool
->shrinker
.seeks
= DEFAULT_SEEKS
;
2340 return register_shrinker(&pool
->shrinker
);
2344 * zs_create_pool - Creates an allocation pool to work from.
2345 * @name: pool name to be created
2347 * This function must be called before anything when using
2348 * the zsmalloc allocator.
2350 * On success, a pointer to the newly created pool is returned,
2353 struct zs_pool
*zs_create_pool(const char *name
)
2356 struct zs_pool
*pool
;
2357 struct size_class
*prev_class
= NULL
;
2359 pool
= kzalloc(sizeof(*pool
), GFP_KERNEL
);
2363 init_deferred_free(pool
);
2365 pool
->name
= kstrdup(name
, GFP_KERNEL
);
2369 #ifdef CONFIG_COMPACTION
2370 init_waitqueue_head(&pool
->migration_wait
);
2373 if (create_cache(pool
))
2377 * Iterate reversely, because, size of size_class that we want to use
2378 * for merging should be larger or equal to current size.
2380 for (i
= ZS_SIZE_CLASSES
- 1; i
>= 0; i
--) {
2382 int pages_per_zspage
;
2383 int objs_per_zspage
;
2384 struct size_class
*class;
2387 size
= ZS_MIN_ALLOC_SIZE
+ i
* ZS_SIZE_CLASS_DELTA
;
2388 if (size
> ZS_MAX_ALLOC_SIZE
)
2389 size
= ZS_MAX_ALLOC_SIZE
;
2390 pages_per_zspage
= get_pages_per_zspage(size
);
2391 objs_per_zspage
= pages_per_zspage
* PAGE_SIZE
/ size
;
2394 * We iterate from biggest down to smallest classes,
2395 * so huge_class_size holds the size of the first huge
2396 * class. Any object bigger than or equal to that will
2397 * endup in the huge class.
2399 if (pages_per_zspage
!= 1 && objs_per_zspage
!= 1 &&
2401 huge_class_size
= size
;
2403 * The object uses ZS_HANDLE_SIZE bytes to store the
2404 * handle. We need to subtract it, because zs_malloc()
2405 * unconditionally adds handle size before it performs
2406 * size class search - so object may be smaller than
2407 * huge class size, yet it still can end up in the huge
2408 * class because it grows by ZS_HANDLE_SIZE extra bytes
2409 * right before class lookup.
2411 huge_class_size
-= (ZS_HANDLE_SIZE
- 1);
2415 * size_class is used for normal zsmalloc operation such
2416 * as alloc/free for that size. Although it is natural that we
2417 * have one size_class for each size, there is a chance that we
2418 * can get more memory utilization if we use one size_class for
2419 * many different sizes whose size_class have same
2420 * characteristics. So, we makes size_class point to
2421 * previous size_class if possible.
2424 if (can_merge(prev_class
, pages_per_zspage
, objs_per_zspage
)) {
2425 pool
->size_class
[i
] = prev_class
;
2430 class = kzalloc(sizeof(struct size_class
), GFP_KERNEL
);
2436 class->pages_per_zspage
= pages_per_zspage
;
2437 class->objs_per_zspage
= objs_per_zspage
;
2438 spin_lock_init(&class->lock
);
2439 pool
->size_class
[i
] = class;
2440 for (fullness
= ZS_EMPTY
; fullness
< NR_ZS_FULLNESS
;
2442 INIT_LIST_HEAD(&class->fullness_list
[fullness
]);
2447 /* debug only, don't abort if it fails */
2448 zs_pool_stat_create(pool
, name
);
2450 if (zs_register_migration(pool
))
2454 * Not critical since shrinker is only used to trigger internal
2455 * defragmentation of the pool which is pretty optional thing. If
2456 * registration fails we still can use the pool normally and user can
2457 * trigger compaction manually. Thus, ignore return code.
2459 zs_register_shrinker(pool
);
2464 zs_destroy_pool(pool
);
2467 EXPORT_SYMBOL_GPL(zs_create_pool
);
2469 void zs_destroy_pool(struct zs_pool
*pool
)
2473 zs_unregister_shrinker(pool
);
2474 zs_unregister_migration(pool
);
2475 zs_pool_stat_destroy(pool
);
2477 for (i
= 0; i
< ZS_SIZE_CLASSES
; i
++) {
2479 struct size_class
*class = pool
->size_class
[i
];
2484 if (class->index
!= i
)
2487 for (fg
= ZS_EMPTY
; fg
< NR_ZS_FULLNESS
; fg
++) {
2488 if (!list_empty(&class->fullness_list
[fg
])) {
2489 pr_info("Freeing non-empty class with size %db, fullness group %d\n",
2496 destroy_cache(pool
);
2500 EXPORT_SYMBOL_GPL(zs_destroy_pool
);
2502 static int __init
zs_init(void)
2506 ret
= zsmalloc_mount();
2510 ret
= cpuhp_setup_state(CPUHP_MM_ZS_PREPARE
, "mm/zsmalloc:prepare",
2511 zs_cpu_prepare
, zs_cpu_dead
);
2516 zpool_register_driver(&zs_zpool_driver
);
2529 static void __exit
zs_exit(void)
2532 zpool_unregister_driver(&zs_zpool_driver
);
2535 cpuhp_remove_state(CPUHP_MM_ZS_PREPARE
);
2540 module_init(zs_init
);
2541 module_exit(zs_exit
);
2543 MODULE_LICENSE("Dual BSD/GPL");
2544 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");