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 the first component (0-order) page
20 * page->index (union with page->freelist): offset of the first object
21 * starting in this page. For the first page, this is
22 * always 0, so we use this field (aka freelist) to point
23 * to the first free object in zspage.
24 * page->lru: links together all component pages (except the first page)
27 * For _first_ page only:
29 * page->private: refers to the component page after the first page
30 * If the page is first_page for huge object, it stores handle.
31 * Look at size_class->huge.
32 * page->freelist: points to the first free object in zspage.
33 * Free objects are linked together using in-place
35 * page->lru: links together first pages of various zspages.
36 * Basically forming list of zspages in a fullness group.
37 * page->mapping: class index and fullness group of the zspage
38 * page->inuse: the number of objects that are used in this zspage
40 * Usage of struct page flags:
41 * PG_private: identifies the first component page
42 * PG_private2: identifies the last component page
46 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
48 #include <linux/module.h>
49 #include <linux/kernel.h>
50 #include <linux/sched.h>
51 #include <linux/bitops.h>
52 #include <linux/errno.h>
53 #include <linux/highmem.h>
54 #include <linux/string.h>
55 #include <linux/slab.h>
56 #include <asm/tlbflush.h>
57 #include <asm/pgtable.h>
58 #include <linux/cpumask.h>
59 #include <linux/cpu.h>
60 #include <linux/vmalloc.h>
61 #include <linux/preempt.h>
62 #include <linux/spinlock.h>
63 #include <linux/types.h>
64 #include <linux/debugfs.h>
65 #include <linux/zsmalloc.h>
66 #include <linux/zpool.h>
69 * This must be power of 2 and greater than of equal to sizeof(link_free).
70 * These two conditions ensure that any 'struct link_free' itself doesn't
71 * span more than 1 page which avoids complex case of mapping 2 pages simply
72 * to restore link_free pointer values.
77 * A single 'zspage' is composed of up to 2^N discontiguous 0-order (single)
78 * pages. ZS_MAX_ZSPAGE_ORDER defines upper limit on N.
80 #define ZS_MAX_ZSPAGE_ORDER 2
81 #define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER)
83 #define ZS_HANDLE_SIZE (sizeof(unsigned long))
86 * Object location (<PFN>, <obj_idx>) is encoded as
87 * as single (unsigned long) handle value.
89 * Note that object index <obj_idx> is relative to system
90 * page <PFN> it is stored in, so for each sub-page belonging
91 * to a zspage, obj_idx starts with 0.
93 * This is made more complicated by various memory models and PAE.
96 #ifndef MAX_PHYSMEM_BITS
97 #ifdef CONFIG_HIGHMEM64G
98 #define MAX_PHYSMEM_BITS 36
99 #else /* !CONFIG_HIGHMEM64G */
101 * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just
104 #define MAX_PHYSMEM_BITS BITS_PER_LONG
107 #define _PFN_BITS (MAX_PHYSMEM_BITS - PAGE_SHIFT)
110 * Memory for allocating for handle keeps object position by
111 * encoding <page, obj_idx> and the encoded value has a room
112 * in least bit(ie, look at obj_to_location).
113 * We use the bit to synchronize between object access by
114 * user and migration.
116 #define HANDLE_PIN_BIT 0
119 * Head in allocated object should have OBJ_ALLOCATED_TAG
120 * to identify the object was allocated or not.
121 * It's okay to add the status bit in the least bit because
122 * header keeps handle which is 4byte-aligned address so we
123 * have room for two bit at least.
125 #define OBJ_ALLOCATED_TAG 1
126 #define OBJ_TAG_BITS 1
127 #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
128 #define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
130 #define MAX(a, b) ((a) >= (b) ? (a) : (b))
131 /* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
132 #define ZS_MIN_ALLOC_SIZE \
133 MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
134 /* each chunk includes extra space to keep handle */
135 #define ZS_MAX_ALLOC_SIZE PAGE_SIZE
138 * On systems with 4K page size, this gives 255 size classes! There is a
140 * - Large number of size classes is potentially wasteful as free page are
141 * spread across these classes
142 * - Small number of size classes causes large internal fragmentation
143 * - Probably its better to use specific size classes (empirically
144 * determined). NOTE: all those class sizes must be set as multiple of
145 * ZS_ALIGN to make sure link_free itself never has to span 2 pages.
147 * ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN
150 #define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> 8)
153 * We do not maintain any list for completely empty or full pages
155 enum fullness_group {
158 _ZS_NR_FULLNESS_GROUPS,
171 #ifdef CONFIG_ZSMALLOC_STAT
172 #define NR_ZS_STAT_TYPE (CLASS_ALMOST_EMPTY + 1)
174 #define NR_ZS_STAT_TYPE (OBJ_USED + 1)
177 struct zs_size_stat {
178 unsigned long objs[NR_ZS_STAT_TYPE];
181 #ifdef CONFIG_ZSMALLOC_STAT
182 static struct dentry *zs_stat_root;
186 * number of size_classes
188 static int zs_size_classes;
191 * We assign a page to ZS_ALMOST_EMPTY fullness group when:
193 * n = number of allocated objects
194 * N = total number of objects zspage can store
195 * f = fullness_threshold_frac
197 * Similarly, we assign zspage to:
198 * ZS_ALMOST_FULL when n > N / f
199 * ZS_EMPTY when n == 0
200 * ZS_FULL when n == N
202 * (see: fix_fullness_group())
204 static const int fullness_threshold_frac = 4;
208 struct page *fullness_list[_ZS_NR_FULLNESS_GROUPS];
210 * Size of objects stored in this class. Must be multiple
217 struct zs_size_stat stats;
219 /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
220 int pages_per_zspage;
221 /* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
226 * Placed within free objects to form a singly linked list.
227 * For every zspage, first_page->freelist gives head of this list.
229 * This must be power of 2 and less than or equal to ZS_ALIGN
234 * Position of next free chunk (encodes <PFN, obj_idx>)
235 * It's valid for non-allocated object
239 * Handle of allocated object.
241 unsigned long handle;
248 struct size_class **size_class;
249 struct kmem_cache *handle_cachep;
251 atomic_long_t pages_allocated;
253 struct zs_pool_stats stats;
255 /* Compact classes */
256 struct shrinker shrinker;
258 * To signify that register_shrinker() was successful
259 * and unregister_shrinker() will not Oops.
261 bool shrinker_enabled;
262 #ifdef CONFIG_ZSMALLOC_STAT
263 struct dentry *stat_dentry;
268 * A zspage's class index and fullness group
269 * are encoded in its (first)page->mapping
271 #define FULLNESS_BITS 4
272 #define CLASS_BITS 28
274 #define FULLNESS_SHIFT 0
275 #define CLASS_SHIFT (FULLNESS_SHIFT + FULLNESS_BITS)
277 #define FULLNESS_MASK ((1UL << FULLNESS_BITS) - 1)
278 #define CLASS_MASK ((1UL << CLASS_BITS) - 1)
280 struct mapping_area {
281 #ifdef CONFIG_PGTABLE_MAPPING
282 struct vm_struct *vm; /* vm area for mapping object that span pages */
284 char *vm_buf; /* copy buffer for objects that span pages */
286 char *vm_addr; /* address of kmap_atomic()'ed pages */
287 enum zs_mapmode vm_mm; /* mapping mode */
290 static int create_handle_cache(struct zs_pool *pool)
292 pool->handle_cachep = kmem_cache_create("zs_handle", ZS_HANDLE_SIZE,
294 return pool->handle_cachep ? 0 : 1;
297 static void destroy_handle_cache(struct zs_pool *pool)
299 kmem_cache_destroy(pool->handle_cachep);
302 static unsigned long alloc_handle(struct zs_pool *pool, gfp_t gfp)
304 return (unsigned long)kmem_cache_alloc(pool->handle_cachep,
305 gfp & ~__GFP_HIGHMEM);
308 static void free_handle(struct zs_pool *pool, unsigned long handle)
310 kmem_cache_free(pool->handle_cachep, (void *)handle);
313 static void record_obj(unsigned long handle, unsigned long obj)
316 * lsb of @obj represents handle lock while other bits
317 * represent object value the handle is pointing so
318 * updating shouldn't do store tearing.
320 WRITE_ONCE(*(unsigned long *)handle, obj);
327 static void *zs_zpool_create(const char *name, gfp_t gfp,
328 const struct zpool_ops *zpool_ops,
332 * Ignore global gfp flags: zs_malloc() may be invoked from
333 * different contexts and its caller must provide a valid
336 return zs_create_pool(name);
339 static void zs_zpool_destroy(void *pool)
341 zs_destroy_pool(pool);
344 static int zs_zpool_malloc(void *pool, size_t size, gfp_t gfp,
345 unsigned long *handle)
347 *handle = zs_malloc(pool, size, gfp);
348 return *handle ? 0 : -1;
350 static void zs_zpool_free(void *pool, unsigned long handle)
352 zs_free(pool, handle);
355 static int zs_zpool_shrink(void *pool, unsigned int pages,
356 unsigned int *reclaimed)
361 static void *zs_zpool_map(void *pool, unsigned long handle,
362 enum zpool_mapmode mm)
364 enum zs_mapmode zs_mm;
373 case ZPOOL_MM_RW: /* fallthru */
379 return zs_map_object(pool, handle, zs_mm);
381 static void zs_zpool_unmap(void *pool, unsigned long handle)
383 zs_unmap_object(pool, handle);
386 static u64 zs_zpool_total_size(void *pool)
388 return zs_get_total_pages(pool) << PAGE_SHIFT;
391 static struct zpool_driver zs_zpool_driver = {
393 .owner = THIS_MODULE,
394 .create = zs_zpool_create,
395 .destroy = zs_zpool_destroy,
396 .malloc = zs_zpool_malloc,
397 .free = zs_zpool_free,
398 .shrink = zs_zpool_shrink,
400 .unmap = zs_zpool_unmap,
401 .total_size = zs_zpool_total_size,
404 MODULE_ALIAS("zpool-zsmalloc");
405 #endif /* CONFIG_ZPOOL */
407 static unsigned int get_maxobj_per_zspage(int size, int pages_per_zspage)
409 return pages_per_zspage * PAGE_SIZE / size;
412 /* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
413 static DEFINE_PER_CPU(struct mapping_area, zs_map_area);
415 static int is_first_page(struct page *page)
417 return PagePrivate(page);
420 static int is_last_page(struct page *page)
422 return PagePrivate2(page);
425 static inline int get_zspage_inuse(struct page *first_page)
427 return first_page->inuse;
430 static inline void set_zspage_inuse(struct page *first_page, int val)
432 first_page->inuse = val;
435 static inline void mod_zspage_inuse(struct page *first_page, int val)
437 first_page->inuse += val;
440 static inline int get_first_obj_offset(struct page *page)
445 static inline void set_first_obj_offset(struct page *page, int offset)
447 page->index = offset;
450 static inline unsigned long get_freeobj(struct page *first_page)
452 return (unsigned long)first_page->freelist;
455 static inline void set_freeobj(struct page *first_page, unsigned long obj)
457 first_page->freelist = (void *)obj;
460 static void get_zspage_mapping(struct page *first_page,
461 unsigned int *class_idx,
462 enum fullness_group *fullness)
465 VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
467 m = (unsigned long)first_page->mapping;
468 *fullness = (m >> FULLNESS_SHIFT) & FULLNESS_MASK;
469 *class_idx = (m >> CLASS_SHIFT) & CLASS_MASK;
472 static void set_zspage_mapping(struct page *first_page,
473 unsigned int class_idx,
474 enum fullness_group fullness)
477 VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
479 m = (class_idx << CLASS_SHIFT) | (fullness << FULLNESS_SHIFT);
480 first_page->mapping = (struct address_space *)m;
484 * zsmalloc divides the pool into various size classes where each
485 * class maintains a list of zspages where each zspage is divided
486 * into equal sized chunks. Each allocation falls into one of these
487 * classes depending on its size. This function returns index of the
488 * size class which has chunk size big enough to hold the give size.
490 static int get_size_class_index(int size)
494 if (likely(size > ZS_MIN_ALLOC_SIZE))
495 idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE,
496 ZS_SIZE_CLASS_DELTA);
498 return min(zs_size_classes - 1, idx);
501 static inline void zs_stat_inc(struct size_class *class,
502 enum zs_stat_type type, unsigned long cnt)
504 if (type < NR_ZS_STAT_TYPE)
505 class->stats.objs[type] += cnt;
508 static inline void zs_stat_dec(struct size_class *class,
509 enum zs_stat_type type, unsigned long cnt)
511 if (type < NR_ZS_STAT_TYPE)
512 class->stats.objs[type] -= cnt;
515 static inline unsigned long zs_stat_get(struct size_class *class,
516 enum zs_stat_type type)
518 if (type < NR_ZS_STAT_TYPE)
519 return class->stats.objs[type];
523 #ifdef CONFIG_ZSMALLOC_STAT
525 static void __init zs_stat_init(void)
527 if (!debugfs_initialized()) {
528 pr_warn("debugfs not available, stat dir not created\n");
532 zs_stat_root = debugfs_create_dir("zsmalloc", NULL);
534 pr_warn("debugfs 'zsmalloc' stat dir creation failed\n");
537 static void __exit zs_stat_exit(void)
539 debugfs_remove_recursive(zs_stat_root);
542 static unsigned long zs_can_compact(struct size_class *class);
544 static int zs_stats_size_show(struct seq_file *s, void *v)
547 struct zs_pool *pool = s->private;
548 struct size_class *class;
550 unsigned long class_almost_full, class_almost_empty;
551 unsigned long obj_allocated, obj_used, pages_used, freeable;
552 unsigned long total_class_almost_full = 0, total_class_almost_empty = 0;
553 unsigned long total_objs = 0, total_used_objs = 0, total_pages = 0;
554 unsigned long total_freeable = 0;
556 seq_printf(s, " %5s %5s %11s %12s %13s %10s %10s %16s %8s\n",
557 "class", "size", "almost_full", "almost_empty",
558 "obj_allocated", "obj_used", "pages_used",
559 "pages_per_zspage", "freeable");
561 for (i = 0; i < zs_size_classes; i++) {
562 class = pool->size_class[i];
564 if (class->index != i)
567 spin_lock(&class->lock);
568 class_almost_full = zs_stat_get(class, CLASS_ALMOST_FULL);
569 class_almost_empty = zs_stat_get(class, CLASS_ALMOST_EMPTY);
570 obj_allocated = zs_stat_get(class, OBJ_ALLOCATED);
571 obj_used = zs_stat_get(class, OBJ_USED);
572 freeable = zs_can_compact(class);
573 spin_unlock(&class->lock);
575 objs_per_zspage = get_maxobj_per_zspage(class->size,
576 class->pages_per_zspage);
577 pages_used = obj_allocated / objs_per_zspage *
578 class->pages_per_zspage;
580 seq_printf(s, " %5u %5u %11lu %12lu %13lu"
581 " %10lu %10lu %16d %8lu\n",
582 i, class->size, class_almost_full, class_almost_empty,
583 obj_allocated, obj_used, pages_used,
584 class->pages_per_zspage, freeable);
586 total_class_almost_full += class_almost_full;
587 total_class_almost_empty += class_almost_empty;
588 total_objs += obj_allocated;
589 total_used_objs += obj_used;
590 total_pages += pages_used;
591 total_freeable += freeable;
595 seq_printf(s, " %5s %5s %11lu %12lu %13lu %10lu %10lu %16s %8lu\n",
596 "Total", "", total_class_almost_full,
597 total_class_almost_empty, total_objs,
598 total_used_objs, total_pages, "", total_freeable);
603 static int zs_stats_size_open(struct inode *inode, struct file *file)
605 return single_open(file, zs_stats_size_show, inode->i_private);
608 static const struct file_operations zs_stat_size_ops = {
609 .open = zs_stats_size_open,
612 .release = single_release,
615 static void zs_pool_stat_create(struct zs_pool *pool, const char *name)
617 struct dentry *entry;
620 pr_warn("no root stat dir, not creating <%s> stat dir\n", name);
624 entry = debugfs_create_dir(name, zs_stat_root);
626 pr_warn("debugfs dir <%s> creation failed\n", name);
629 pool->stat_dentry = entry;
631 entry = debugfs_create_file("classes", S_IFREG | S_IRUGO,
632 pool->stat_dentry, pool, &zs_stat_size_ops);
634 pr_warn("%s: debugfs file entry <%s> creation failed\n",
636 debugfs_remove_recursive(pool->stat_dentry);
637 pool->stat_dentry = NULL;
641 static void zs_pool_stat_destroy(struct zs_pool *pool)
643 debugfs_remove_recursive(pool->stat_dentry);
646 #else /* CONFIG_ZSMALLOC_STAT */
647 static void __init zs_stat_init(void)
651 static void __exit zs_stat_exit(void)
655 static inline void zs_pool_stat_create(struct zs_pool *pool, const char *name)
659 static inline void zs_pool_stat_destroy(struct zs_pool *pool)
665 * For each size class, zspages are divided into different groups
666 * depending on how "full" they are. This was done so that we could
667 * easily find empty or nearly empty zspages when we try to shrink
668 * the pool (not yet implemented). This function returns fullness
669 * status of the given page.
671 static enum fullness_group get_fullness_group(struct size_class *class,
672 struct page *first_page)
674 int inuse, objs_per_zspage;
675 enum fullness_group fg;
677 VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
679 inuse = get_zspage_inuse(first_page);
680 objs_per_zspage = class->objs_per_zspage;
684 else if (inuse == objs_per_zspage)
686 else if (inuse <= 3 * objs_per_zspage / fullness_threshold_frac)
687 fg = ZS_ALMOST_EMPTY;
695 * Each size class maintains various freelists and zspages are assigned
696 * to one of these freelists based on the number of live objects they
697 * have. This functions inserts the given zspage into the freelist
698 * identified by <class, fullness_group>.
700 static void insert_zspage(struct size_class *class,
701 enum fullness_group fullness,
702 struct page *first_page)
706 VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
708 if (fullness >= _ZS_NR_FULLNESS_GROUPS)
711 zs_stat_inc(class, fullness == ZS_ALMOST_EMPTY ?
712 CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);
714 head = &class->fullness_list[fullness];
721 * We want to see more ZS_FULL pages and less almost
722 * empty/full. Put pages with higher ->inuse first.
724 list_add_tail(&first_page->lru, &(*head)->lru);
725 if (get_zspage_inuse(first_page) >= get_zspage_inuse(*head))
730 * This function removes the given zspage from the freelist identified
731 * by <class, fullness_group>.
733 static void remove_zspage(struct size_class *class,
734 enum fullness_group fullness,
735 struct page *first_page)
739 VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
741 if (fullness >= _ZS_NR_FULLNESS_GROUPS)
744 head = &class->fullness_list[fullness];
745 VM_BUG_ON_PAGE(!*head, first_page);
746 if (list_empty(&(*head)->lru))
748 else if (*head == first_page)
749 *head = (struct page *)list_entry((*head)->lru.next,
752 list_del_init(&first_page->lru);
753 zs_stat_dec(class, fullness == ZS_ALMOST_EMPTY ?
754 CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);
758 * Each size class maintains zspages in different fullness groups depending
759 * on the number of live objects they contain. When allocating or freeing
760 * objects, the fullness status of the page can change, say, from ALMOST_FULL
761 * to ALMOST_EMPTY when freeing an object. This function checks if such
762 * a status change has occurred for the given page and accordingly moves the
763 * page from the freelist of the old fullness group to that of the new
766 static enum fullness_group fix_fullness_group(struct size_class *class,
767 struct page *first_page)
770 enum fullness_group currfg, newfg;
772 get_zspage_mapping(first_page, &class_idx, &currfg);
773 newfg = get_fullness_group(class, first_page);
777 remove_zspage(class, currfg, first_page);
778 insert_zspage(class, newfg, first_page);
779 set_zspage_mapping(first_page, class_idx, newfg);
786 * We have to decide on how many pages to link together
787 * to form a zspage for each size class. This is important
788 * to reduce wastage due to unusable space left at end of
789 * each zspage which is given as:
790 * wastage = Zp % class_size
791 * usage = Zp - wastage
792 * where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ...
794 * For example, for size class of 3/8 * PAGE_SIZE, we should
795 * link together 3 PAGE_SIZE sized pages to form a zspage
796 * since then we can perfectly fit in 8 such objects.
798 static int get_pages_per_zspage(int class_size)
800 int i, max_usedpc = 0;
801 /* zspage order which gives maximum used size per KB */
802 int max_usedpc_order = 1;
804 for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) {
808 zspage_size = i * PAGE_SIZE;
809 waste = zspage_size % class_size;
810 usedpc = (zspage_size - waste) * 100 / zspage_size;
812 if (usedpc > max_usedpc) {
814 max_usedpc_order = i;
818 return max_usedpc_order;
822 * A single 'zspage' is composed of many system pages which are
823 * linked together using fields in struct page. This function finds
824 * the first/head page, given any component page of a zspage.
826 static struct page *get_first_page(struct page *page)
828 if (is_first_page(page))
831 return (struct page *)page_private(page);
834 static struct page *get_next_page(struct page *page)
838 if (is_last_page(page))
840 else if (is_first_page(page))
841 next = (struct page *)page_private(page);
843 next = list_entry(page->lru.next, struct page, lru);
849 * Encode <page, obj_idx> as a single handle value.
850 * We use the least bit of handle for tagging.
852 static void *location_to_obj(struct page *page, unsigned long obj_idx)
861 obj = page_to_pfn(page) << OBJ_INDEX_BITS;
862 obj |= ((obj_idx) & OBJ_INDEX_MASK);
863 obj <<= OBJ_TAG_BITS;
869 * Decode <page, obj_idx> pair from the given object handle. We adjust the
870 * decoded obj_idx back to its original value since it was adjusted in
873 static void obj_to_location(unsigned long obj, struct page **page,
874 unsigned long *obj_idx)
876 obj >>= OBJ_TAG_BITS;
877 *page = pfn_to_page(obj >> OBJ_INDEX_BITS);
878 *obj_idx = (obj & OBJ_INDEX_MASK);
881 static unsigned long handle_to_obj(unsigned long handle)
883 return *(unsigned long *)handle;
886 static unsigned long obj_to_head(struct size_class *class, struct page *page,
890 VM_BUG_ON_PAGE(!is_first_page(page), page);
891 return page_private(page);
893 return *(unsigned long *)obj;
896 static unsigned long obj_idx_to_offset(struct page *page,
897 unsigned long obj_idx, int class_size)
899 unsigned long off = 0;
901 if (!is_first_page(page))
902 off = get_first_obj_offset(page);
904 return off + obj_idx * class_size;
907 static inline int trypin_tag(unsigned long handle)
909 return bit_spin_trylock(HANDLE_PIN_BIT, (unsigned long *)handle);
912 static void pin_tag(unsigned long handle)
914 bit_spin_lock(HANDLE_PIN_BIT, (unsigned long *)handle);
917 static void unpin_tag(unsigned long handle)
919 bit_spin_unlock(HANDLE_PIN_BIT, (unsigned long *)handle);
922 static void reset_page(struct page *page)
924 clear_bit(PG_private, &page->flags);
925 clear_bit(PG_private_2, &page->flags);
926 set_page_private(page, 0);
927 page->mapping = NULL;
928 page->freelist = NULL;
929 page_mapcount_reset(page);
932 static void free_zspage(struct page *first_page)
934 struct page *nextp, *tmp, *head_extra;
936 VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
937 VM_BUG_ON_PAGE(get_zspage_inuse(first_page), first_page);
939 head_extra = (struct page *)page_private(first_page);
941 reset_page(first_page);
942 __free_page(first_page);
944 /* zspage with only 1 system page */
948 list_for_each_entry_safe(nextp, tmp, &head_extra->lru, lru) {
949 list_del(&nextp->lru);
953 reset_page(head_extra);
954 __free_page(head_extra);
957 /* Initialize a newly allocated zspage */
958 static void init_zspage(struct size_class *class, struct page *first_page)
960 unsigned long off = 0;
961 struct page *page = first_page;
963 VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
966 struct page *next_page;
967 struct link_free *link;
972 * page->index stores offset of first object starting
973 * in the page. For the first page, this is always 0,
974 * so we use first_page->index (aka ->freelist) to store
975 * head of corresponding zspage's freelist.
977 if (page != first_page)
978 set_first_obj_offset(page, off);
980 vaddr = kmap_atomic(page);
981 link = (struct link_free *)vaddr + off / sizeof(*link);
983 while ((off += class->size) < PAGE_SIZE) {
984 link->next = location_to_obj(page, i++);
985 link += class->size / sizeof(*link);
989 * We now come to the last (full or partial) object on this
990 * page, which must point to the first object on the next
993 next_page = get_next_page(page);
994 link->next = location_to_obj(next_page, 0);
995 kunmap_atomic(vaddr);
1002 * Allocate a zspage for the given size class
1004 static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
1007 struct page *first_page = NULL, *uninitialized_var(prev_page);
1010 * Allocate individual pages and link them together as:
1011 * 1. first page->private = first sub-page
1012 * 2. all sub-pages are linked together using page->lru
1013 * 3. each sub-page is linked to the first page using page->private
1015 * For each size class, First/Head pages are linked together using
1016 * page->lru. Also, we set PG_private to identify the first page
1017 * (i.e. no other sub-page has this flag set) and PG_private_2 to
1018 * identify the last page.
1021 for (i = 0; i < class->pages_per_zspage; i++) {
1024 page = alloc_page(flags);
1028 INIT_LIST_HEAD(&page->lru);
1029 if (i == 0) { /* first page */
1030 SetPagePrivate(page);
1031 set_page_private(page, 0);
1033 set_zspage_inuse(first_page, 0);
1036 set_page_private(first_page, (unsigned long)page);
1038 set_page_private(page, (unsigned long)first_page);
1040 list_add(&page->lru, &prev_page->lru);
1041 if (i == class->pages_per_zspage - 1) /* last page */
1042 SetPagePrivate2(page);
1046 init_zspage(class, first_page);
1048 set_freeobj(first_page, (unsigned long)location_to_obj(first_page, 0));
1049 error = 0; /* Success */
1052 if (unlikely(error) && first_page) {
1053 free_zspage(first_page);
1060 static struct page *find_get_zspage(struct size_class *class)
1065 for (i = 0; i < _ZS_NR_FULLNESS_GROUPS; i++) {
1066 page = class->fullness_list[i];
1074 #ifdef CONFIG_PGTABLE_MAPPING
1075 static inline int __zs_cpu_up(struct mapping_area *area)
1078 * Make sure we don't leak memory if a cpu UP notification
1079 * and zs_init() race and both call zs_cpu_up() on the same cpu
1083 area->vm = alloc_vm_area(PAGE_SIZE * 2, NULL);
1089 static inline void __zs_cpu_down(struct mapping_area *area)
1092 free_vm_area(area->vm);
1096 static inline void *__zs_map_object(struct mapping_area *area,
1097 struct page *pages[2], int off, int size)
1099 BUG_ON(map_vm_area(area->vm, PAGE_KERNEL, pages));
1100 area->vm_addr = area->vm->addr;
1101 return area->vm_addr + off;
1104 static inline void __zs_unmap_object(struct mapping_area *area,
1105 struct page *pages[2], int off, int size)
1107 unsigned long addr = (unsigned long)area->vm_addr;
1109 unmap_kernel_range(addr, PAGE_SIZE * 2);
1112 #else /* CONFIG_PGTABLE_MAPPING */
1114 static inline int __zs_cpu_up(struct mapping_area *area)
1117 * Make sure we don't leak memory if a cpu UP notification
1118 * and zs_init() race and both call zs_cpu_up() on the same cpu
1122 area->vm_buf = kmalloc(ZS_MAX_ALLOC_SIZE, GFP_KERNEL);
1128 static inline void __zs_cpu_down(struct mapping_area *area)
1130 kfree(area->vm_buf);
1131 area->vm_buf = NULL;
1134 static void *__zs_map_object(struct mapping_area *area,
1135 struct page *pages[2], int off, int size)
1139 char *buf = area->vm_buf;
1141 /* disable page faults to match kmap_atomic() return conditions */
1142 pagefault_disable();
1144 /* no read fastpath */
1145 if (area->vm_mm == ZS_MM_WO)
1148 sizes[0] = PAGE_SIZE - off;
1149 sizes[1] = size - sizes[0];
1151 /* copy object to per-cpu buffer */
1152 addr = kmap_atomic(pages[0]);
1153 memcpy(buf, addr + off, sizes[0]);
1154 kunmap_atomic(addr);
1155 addr = kmap_atomic(pages[1]);
1156 memcpy(buf + sizes[0], addr, sizes[1]);
1157 kunmap_atomic(addr);
1159 return area->vm_buf;
1162 static void __zs_unmap_object(struct mapping_area *area,
1163 struct page *pages[2], int off, int size)
1169 /* no write fastpath */
1170 if (area->vm_mm == ZS_MM_RO)
1174 buf = buf + ZS_HANDLE_SIZE;
1175 size -= ZS_HANDLE_SIZE;
1176 off += ZS_HANDLE_SIZE;
1178 sizes[0] = PAGE_SIZE - off;
1179 sizes[1] = size - sizes[0];
1181 /* copy per-cpu buffer to object */
1182 addr = kmap_atomic(pages[0]);
1183 memcpy(addr + off, buf, sizes[0]);
1184 kunmap_atomic(addr);
1185 addr = kmap_atomic(pages[1]);
1186 memcpy(addr, buf + sizes[0], sizes[1]);
1187 kunmap_atomic(addr);
1190 /* enable page faults to match kunmap_atomic() return conditions */
1194 #endif /* CONFIG_PGTABLE_MAPPING */
1196 static int zs_cpu_notifier(struct notifier_block *nb, unsigned long action,
1199 int ret, cpu = (long)pcpu;
1200 struct mapping_area *area;
1203 case CPU_UP_PREPARE:
1204 area = &per_cpu(zs_map_area, cpu);
1205 ret = __zs_cpu_up(area);
1207 return notifier_from_errno(ret);
1210 case CPU_UP_CANCELED:
1211 area = &per_cpu(zs_map_area, cpu);
1212 __zs_cpu_down(area);
1219 static struct notifier_block zs_cpu_nb = {
1220 .notifier_call = zs_cpu_notifier
1223 static int zs_register_cpu_notifier(void)
1225 int cpu, uninitialized_var(ret);
1227 cpu_notifier_register_begin();
1229 __register_cpu_notifier(&zs_cpu_nb);
1230 for_each_online_cpu(cpu) {
1231 ret = zs_cpu_notifier(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
1232 if (notifier_to_errno(ret))
1236 cpu_notifier_register_done();
1237 return notifier_to_errno(ret);
1240 static void zs_unregister_cpu_notifier(void)
1244 cpu_notifier_register_begin();
1246 for_each_online_cpu(cpu)
1247 zs_cpu_notifier(NULL, CPU_DEAD, (void *)(long)cpu);
1248 __unregister_cpu_notifier(&zs_cpu_nb);
1250 cpu_notifier_register_done();
1253 static void init_zs_size_classes(void)
1257 nr = (ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / ZS_SIZE_CLASS_DELTA + 1;
1258 if ((ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) % ZS_SIZE_CLASS_DELTA)
1261 zs_size_classes = nr;
1264 static bool can_merge(struct size_class *prev, int size, int pages_per_zspage)
1266 if (prev->pages_per_zspage != pages_per_zspage)
1269 if (get_maxobj_per_zspage(prev->size, prev->pages_per_zspage)
1270 != get_maxobj_per_zspage(size, pages_per_zspage))
1276 static bool zspage_full(struct size_class *class, struct page *first_page)
1278 VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
1280 return get_zspage_inuse(first_page) == class->objs_per_zspage;
1283 unsigned long zs_get_total_pages(struct zs_pool *pool)
1285 return atomic_long_read(&pool->pages_allocated);
1287 EXPORT_SYMBOL_GPL(zs_get_total_pages);
1290 * zs_map_object - get address of allocated object from handle.
1291 * @pool: pool from which the object was allocated
1292 * @handle: handle returned from zs_malloc
1294 * Before using an object allocated from zs_malloc, it must be mapped using
1295 * this function. When done with the object, it must be unmapped using
1298 * Only one object can be mapped per cpu at a time. There is no protection
1299 * against nested mappings.
1301 * This function returns with preemption and page faults disabled.
1303 void *zs_map_object(struct zs_pool *pool, unsigned long handle,
1307 unsigned long obj, obj_idx, off;
1309 unsigned int class_idx;
1310 enum fullness_group fg;
1311 struct size_class *class;
1312 struct mapping_area *area;
1313 struct page *pages[2];
1317 * Because we use per-cpu mapping areas shared among the
1318 * pools/users, we can't allow mapping in interrupt context
1319 * because it can corrupt another users mappings.
1321 WARN_ON_ONCE(in_interrupt());
1323 /* From now on, migration cannot move the object */
1326 obj = handle_to_obj(handle);
1327 obj_to_location(obj, &page, &obj_idx);
1328 get_zspage_mapping(get_first_page(page), &class_idx, &fg);
1329 class = pool->size_class[class_idx];
1330 off = obj_idx_to_offset(page, obj_idx, class->size);
1332 area = &get_cpu_var(zs_map_area);
1334 if (off + class->size <= PAGE_SIZE) {
1335 /* this object is contained entirely within a page */
1336 area->vm_addr = kmap_atomic(page);
1337 ret = area->vm_addr + off;
1341 /* this object spans two pages */
1343 pages[1] = get_next_page(page);
1346 ret = __zs_map_object(area, pages, off, class->size);
1349 ret += ZS_HANDLE_SIZE;
1353 EXPORT_SYMBOL_GPL(zs_map_object);
1355 void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
1358 unsigned long obj, obj_idx, off;
1360 unsigned int class_idx;
1361 enum fullness_group fg;
1362 struct size_class *class;
1363 struct mapping_area *area;
1365 obj = handle_to_obj(handle);
1366 obj_to_location(obj, &page, &obj_idx);
1367 get_zspage_mapping(get_first_page(page), &class_idx, &fg);
1368 class = pool->size_class[class_idx];
1369 off = obj_idx_to_offset(page, obj_idx, class->size);
1371 area = this_cpu_ptr(&zs_map_area);
1372 if (off + class->size <= PAGE_SIZE)
1373 kunmap_atomic(area->vm_addr);
1375 struct page *pages[2];
1378 pages[1] = get_next_page(page);
1381 __zs_unmap_object(area, pages, off, class->size);
1383 put_cpu_var(zs_map_area);
1386 EXPORT_SYMBOL_GPL(zs_unmap_object);
1388 static unsigned long obj_malloc(struct size_class *class,
1389 struct page *first_page, unsigned long handle)
1392 struct link_free *link;
1394 struct page *m_page;
1395 unsigned long m_objidx, m_offset;
1398 handle |= OBJ_ALLOCATED_TAG;
1399 obj = get_freeobj(first_page);
1400 obj_to_location(obj, &m_page, &m_objidx);
1401 m_offset = obj_idx_to_offset(m_page, m_objidx, class->size);
1403 vaddr = kmap_atomic(m_page);
1404 link = (struct link_free *)vaddr + m_offset / sizeof(*link);
1405 set_freeobj(first_page, (unsigned long)link->next);
1407 /* record handle in the header of allocated chunk */
1408 link->handle = handle;
1410 /* record handle in first_page->private */
1411 set_page_private(first_page, handle);
1412 kunmap_atomic(vaddr);
1413 mod_zspage_inuse(first_page, 1);
1414 zs_stat_inc(class, OBJ_USED, 1);
1421 * zs_malloc - Allocate block of given size from pool.
1422 * @pool: pool to allocate from
1423 * @size: size of block to allocate
1425 * On success, handle to the allocated object is returned,
1427 * Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
1429 unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
1431 unsigned long handle, obj;
1432 struct size_class *class;
1433 struct page *first_page;
1435 if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
1438 handle = alloc_handle(pool, gfp);
1442 /* extra space in chunk to keep the handle */
1443 size += ZS_HANDLE_SIZE;
1444 class = pool->size_class[get_size_class_index(size)];
1446 spin_lock(&class->lock);
1447 first_page = find_get_zspage(class);
1450 spin_unlock(&class->lock);
1451 first_page = alloc_zspage(class, gfp);
1452 if (unlikely(!first_page)) {
1453 free_handle(pool, handle);
1457 set_zspage_mapping(first_page, class->index, ZS_EMPTY);
1458 atomic_long_add(class->pages_per_zspage,
1459 &pool->pages_allocated);
1461 spin_lock(&class->lock);
1462 zs_stat_inc(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
1463 class->size, class->pages_per_zspage));
1466 obj = obj_malloc(class, first_page, handle);
1467 /* Now move the zspage to another fullness group, if required */
1468 fix_fullness_group(class, first_page);
1469 record_obj(handle, obj);
1470 spin_unlock(&class->lock);
1474 EXPORT_SYMBOL_GPL(zs_malloc);
1476 static void obj_free(struct size_class *class, unsigned long obj)
1478 struct link_free *link;
1479 struct page *first_page, *f_page;
1480 unsigned long f_objidx, f_offset;
1483 obj &= ~OBJ_ALLOCATED_TAG;
1484 obj_to_location(obj, &f_page, &f_objidx);
1485 first_page = get_first_page(f_page);
1487 f_offset = obj_idx_to_offset(f_page, f_objidx, class->size);
1489 vaddr = kmap_atomic(f_page);
1491 /* Insert this object in containing zspage's freelist */
1492 link = (struct link_free *)(vaddr + f_offset);
1493 link->next = (void *)get_freeobj(first_page);
1495 set_page_private(first_page, 0);
1496 kunmap_atomic(vaddr);
1497 set_freeobj(first_page, obj);
1498 mod_zspage_inuse(first_page, -1);
1499 zs_stat_dec(class, OBJ_USED, 1);
1502 void zs_free(struct zs_pool *pool, unsigned long handle)
1504 struct page *first_page, *f_page;
1505 unsigned long obj, f_objidx;
1507 struct size_class *class;
1508 enum fullness_group fullness;
1510 if (unlikely(!handle))
1514 obj = handle_to_obj(handle);
1515 obj_to_location(obj, &f_page, &f_objidx);
1516 first_page = get_first_page(f_page);
1518 get_zspage_mapping(first_page, &class_idx, &fullness);
1519 class = pool->size_class[class_idx];
1521 spin_lock(&class->lock);
1522 obj_free(class, obj);
1523 fullness = fix_fullness_group(class, first_page);
1524 if (fullness == ZS_EMPTY) {
1525 zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
1526 class->size, class->pages_per_zspage));
1527 atomic_long_sub(class->pages_per_zspage,
1528 &pool->pages_allocated);
1529 free_zspage(first_page);
1531 spin_unlock(&class->lock);
1534 free_handle(pool, handle);
1536 EXPORT_SYMBOL_GPL(zs_free);
1538 static void zs_object_copy(struct size_class *class, unsigned long dst,
1541 struct page *s_page, *d_page;
1542 unsigned long s_objidx, d_objidx;
1543 unsigned long s_off, d_off;
1544 void *s_addr, *d_addr;
1545 int s_size, d_size, size;
1548 s_size = d_size = class->size;
1550 obj_to_location(src, &s_page, &s_objidx);
1551 obj_to_location(dst, &d_page, &d_objidx);
1553 s_off = obj_idx_to_offset(s_page, s_objidx, class->size);
1554 d_off = obj_idx_to_offset(d_page, d_objidx, class->size);
1556 if (s_off + class->size > PAGE_SIZE)
1557 s_size = PAGE_SIZE - s_off;
1559 if (d_off + class->size > PAGE_SIZE)
1560 d_size = PAGE_SIZE - d_off;
1562 s_addr = kmap_atomic(s_page);
1563 d_addr = kmap_atomic(d_page);
1566 size = min(s_size, d_size);
1567 memcpy(d_addr + d_off, s_addr + s_off, size);
1570 if (written == class->size)
1578 if (s_off >= PAGE_SIZE) {
1579 kunmap_atomic(d_addr);
1580 kunmap_atomic(s_addr);
1581 s_page = get_next_page(s_page);
1582 s_addr = kmap_atomic(s_page);
1583 d_addr = kmap_atomic(d_page);
1584 s_size = class->size - written;
1588 if (d_off >= PAGE_SIZE) {
1589 kunmap_atomic(d_addr);
1590 d_page = get_next_page(d_page);
1591 d_addr = kmap_atomic(d_page);
1592 d_size = class->size - written;
1597 kunmap_atomic(d_addr);
1598 kunmap_atomic(s_addr);
1602 * Find alloced object in zspage from index object and
1605 static unsigned long find_alloced_obj(struct size_class *class,
1606 struct page *page, int index)
1610 unsigned long handle = 0;
1611 void *addr = kmap_atomic(page);
1613 if (!is_first_page(page))
1614 offset = get_first_obj_offset(page);
1615 offset += class->size * index;
1617 while (offset < PAGE_SIZE) {
1618 head = obj_to_head(class, page, addr + offset);
1619 if (head & OBJ_ALLOCATED_TAG) {
1620 handle = head & ~OBJ_ALLOCATED_TAG;
1621 if (trypin_tag(handle))
1626 offset += class->size;
1630 kunmap_atomic(addr);
1634 struct zs_compact_control {
1635 /* Source page for migration which could be a subpage of zspage. */
1636 struct page *s_page;
1637 /* Destination page for migration which should be a first page
1639 struct page *d_page;
1640 /* Starting object index within @s_page which used for live object
1641 * in the subpage. */
1645 static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
1646 struct zs_compact_control *cc)
1648 unsigned long used_obj, free_obj;
1649 unsigned long handle;
1650 struct page *s_page = cc->s_page;
1651 struct page *d_page = cc->d_page;
1652 unsigned long index = cc->index;
1656 handle = find_alloced_obj(class, s_page, index);
1658 s_page = get_next_page(s_page);
1665 /* Stop if there is no more space */
1666 if (zspage_full(class, d_page)) {
1672 used_obj = handle_to_obj(handle);
1673 free_obj = obj_malloc(class, d_page, handle);
1674 zs_object_copy(class, free_obj, used_obj);
1677 * record_obj updates handle's value to free_obj and it will
1678 * invalidate lock bit(ie, HANDLE_PIN_BIT) of handle, which
1679 * breaks synchronization using pin_tag(e,g, zs_free) so
1680 * let's keep the lock bit.
1682 free_obj |= BIT(HANDLE_PIN_BIT);
1683 record_obj(handle, free_obj);
1685 obj_free(class, used_obj);
1688 /* Remember last position in this iteration */
1689 cc->s_page = s_page;
1695 static struct page *isolate_target_page(struct size_class *class)
1700 for (i = 0; i < _ZS_NR_FULLNESS_GROUPS; i++) {
1701 page = class->fullness_list[i];
1703 remove_zspage(class, i, page);
1712 * putback_zspage - add @first_page into right class's fullness list
1713 * @pool: target pool
1714 * @class: destination class
1715 * @first_page: target page
1717 * Return @fist_page's fullness_group
1719 static enum fullness_group putback_zspage(struct zs_pool *pool,
1720 struct size_class *class,
1721 struct page *first_page)
1723 enum fullness_group fullness;
1725 fullness = get_fullness_group(class, first_page);
1726 insert_zspage(class, fullness, first_page);
1727 set_zspage_mapping(first_page, class->index, fullness);
1729 if (fullness == ZS_EMPTY) {
1730 zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
1731 class->size, class->pages_per_zspage));
1732 atomic_long_sub(class->pages_per_zspage,
1733 &pool->pages_allocated);
1735 free_zspage(first_page);
1741 static struct page *isolate_source_page(struct size_class *class)
1744 struct page *page = NULL;
1746 for (i = ZS_ALMOST_EMPTY; i >= ZS_ALMOST_FULL; i--) {
1747 page = class->fullness_list[i];
1751 remove_zspage(class, i, page);
1760 * Based on the number of unused allocated objects calculate
1761 * and return the number of pages that we can free.
1763 static unsigned long zs_can_compact(struct size_class *class)
1765 unsigned long obj_wasted;
1766 unsigned long obj_allocated = zs_stat_get(class, OBJ_ALLOCATED);
1767 unsigned long obj_used = zs_stat_get(class, OBJ_USED);
1769 if (obj_allocated <= obj_used)
1772 obj_wasted = obj_allocated - obj_used;
1773 obj_wasted /= get_maxobj_per_zspage(class->size,
1774 class->pages_per_zspage);
1776 return obj_wasted * class->pages_per_zspage;
1779 static void __zs_compact(struct zs_pool *pool, struct size_class *class)
1781 struct zs_compact_control cc;
1782 struct page *src_page;
1783 struct page *dst_page = NULL;
1785 spin_lock(&class->lock);
1786 while ((src_page = isolate_source_page(class))) {
1788 if (!zs_can_compact(class))
1792 cc.s_page = src_page;
1794 while ((dst_page = isolate_target_page(class))) {
1795 cc.d_page = dst_page;
1797 * If there is no more space in dst_page, resched
1798 * and see if anyone had allocated another zspage.
1800 if (!migrate_zspage(pool, class, &cc))
1803 putback_zspage(pool, class, dst_page);
1806 /* Stop if we couldn't find slot */
1807 if (dst_page == NULL)
1810 putback_zspage(pool, class, dst_page);
1811 if (putback_zspage(pool, class, src_page) == ZS_EMPTY)
1812 pool->stats.pages_compacted += class->pages_per_zspage;
1813 spin_unlock(&class->lock);
1815 spin_lock(&class->lock);
1819 putback_zspage(pool, class, src_page);
1821 spin_unlock(&class->lock);
1824 unsigned long zs_compact(struct zs_pool *pool)
1827 struct size_class *class;
1829 for (i = zs_size_classes - 1; i >= 0; i--) {
1830 class = pool->size_class[i];
1833 if (class->index != i)
1835 __zs_compact(pool, class);
1838 return pool->stats.pages_compacted;
1840 EXPORT_SYMBOL_GPL(zs_compact);
1842 void zs_pool_stats(struct zs_pool *pool, struct zs_pool_stats *stats)
1844 memcpy(stats, &pool->stats, sizeof(struct zs_pool_stats));
1846 EXPORT_SYMBOL_GPL(zs_pool_stats);
1848 static unsigned long zs_shrinker_scan(struct shrinker *shrinker,
1849 struct shrink_control *sc)
1851 unsigned long pages_freed;
1852 struct zs_pool *pool = container_of(shrinker, struct zs_pool,
1855 pages_freed = pool->stats.pages_compacted;
1857 * Compact classes and calculate compaction delta.
1858 * Can run concurrently with a manually triggered
1859 * (by user) compaction.
1861 pages_freed = zs_compact(pool) - pages_freed;
1863 return pages_freed ? pages_freed : SHRINK_STOP;
1866 static unsigned long zs_shrinker_count(struct shrinker *shrinker,
1867 struct shrink_control *sc)
1870 struct size_class *class;
1871 unsigned long pages_to_free = 0;
1872 struct zs_pool *pool = container_of(shrinker, struct zs_pool,
1875 for (i = zs_size_classes - 1; i >= 0; i--) {
1876 class = pool->size_class[i];
1879 if (class->index != i)
1882 pages_to_free += zs_can_compact(class);
1885 return pages_to_free;
1888 static void zs_unregister_shrinker(struct zs_pool *pool)
1890 if (pool->shrinker_enabled) {
1891 unregister_shrinker(&pool->shrinker);
1892 pool->shrinker_enabled = false;
1896 static int zs_register_shrinker(struct zs_pool *pool)
1898 pool->shrinker.scan_objects = zs_shrinker_scan;
1899 pool->shrinker.count_objects = zs_shrinker_count;
1900 pool->shrinker.batch = 0;
1901 pool->shrinker.seeks = DEFAULT_SEEKS;
1903 return register_shrinker(&pool->shrinker);
1907 * zs_create_pool - Creates an allocation pool to work from.
1908 * @flags: allocation flags used to allocate pool metadata
1910 * This function must be called before anything when using
1911 * the zsmalloc allocator.
1913 * On success, a pointer to the newly created pool is returned,
1916 struct zs_pool *zs_create_pool(const char *name)
1919 struct zs_pool *pool;
1920 struct size_class *prev_class = NULL;
1922 pool = kzalloc(sizeof(*pool), GFP_KERNEL);
1926 pool->size_class = kcalloc(zs_size_classes, sizeof(struct size_class *),
1928 if (!pool->size_class) {
1933 pool->name = kstrdup(name, GFP_KERNEL);
1937 if (create_handle_cache(pool))
1941 * Iterate reversly, because, size of size_class that we want to use
1942 * for merging should be larger or equal to current size.
1944 for (i = zs_size_classes - 1; i >= 0; i--) {
1946 int pages_per_zspage;
1947 struct size_class *class;
1949 size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA;
1950 if (size > ZS_MAX_ALLOC_SIZE)
1951 size = ZS_MAX_ALLOC_SIZE;
1952 pages_per_zspage = get_pages_per_zspage(size);
1955 * size_class is used for normal zsmalloc operation such
1956 * as alloc/free for that size. Although it is natural that we
1957 * have one size_class for each size, there is a chance that we
1958 * can get more memory utilization if we use one size_class for
1959 * many different sizes whose size_class have same
1960 * characteristics. So, we makes size_class point to
1961 * previous size_class if possible.
1964 if (can_merge(prev_class, size, pages_per_zspage)) {
1965 pool->size_class[i] = prev_class;
1970 class = kzalloc(sizeof(struct size_class), GFP_KERNEL);
1976 class->pages_per_zspage = pages_per_zspage;
1977 class->objs_per_zspage = class->pages_per_zspage *
1978 PAGE_SIZE / class->size;
1979 if (pages_per_zspage == 1 && class->objs_per_zspage == 1)
1981 spin_lock_init(&class->lock);
1982 pool->size_class[i] = class;
1987 /* debug only, don't abort if it fails */
1988 zs_pool_stat_create(pool, name);
1991 * Not critical, we still can use the pool
1992 * and user can trigger compaction manually.
1994 if (zs_register_shrinker(pool) == 0)
1995 pool->shrinker_enabled = true;
1999 zs_destroy_pool(pool);
2002 EXPORT_SYMBOL_GPL(zs_create_pool);
2004 void zs_destroy_pool(struct zs_pool *pool)
2008 zs_unregister_shrinker(pool);
2009 zs_pool_stat_destroy(pool);
2011 for (i = 0; i < zs_size_classes; i++) {
2013 struct size_class *class = pool->size_class[i];
2018 if (class->index != i)
2021 for (fg = 0; fg < _ZS_NR_FULLNESS_GROUPS; fg++) {
2022 if (class->fullness_list[fg]) {
2023 pr_info("Freeing non-empty class with size %db, fullness group %d\n",
2030 destroy_handle_cache(pool);
2031 kfree(pool->size_class);
2035 EXPORT_SYMBOL_GPL(zs_destroy_pool);
2037 static int __init zs_init(void)
2039 int ret = zs_register_cpu_notifier();
2044 init_zs_size_classes();
2047 zpool_register_driver(&zs_zpool_driver);
2055 zs_unregister_cpu_notifier();
2060 static void __exit zs_exit(void)
2063 zpool_unregister_driver(&zs_zpool_driver);
2065 zs_unregister_cpu_notifier();
2070 module_init(zs_init);
2071 module_exit(zs_exit);
2073 MODULE_LICENSE("Dual BSD/GPL");
2074 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");