1/*
   2 * zsmalloc memory allocator
   3 *
   4 * Copyright (C) 2011  Nitin Gupta
   5 * Copyright (C) 2012, 2013 Minchan Kim
   6 *
   7 * This code is released using a dual license strategy: BSD/GPL
   8 * You can choose the license that better fits your requirements.
   9 *
  10 * Released under the terms of 3-clause BSD License
  11 * Released under the terms of GNU General Public License Version 2.0
  12 */
  13
  14/*
  15 * Following is how we use various fields and flags of underlying
  16 * struct page(s) to form a zspage.
  17 *
  18 * Usage of struct page fields:
  19 *	page->private: points to zspage
  20 *	page->index: links together all component pages of a zspage
  21 *		For the huge page, this is always 0, so we use this field
  22 *		to store handle.
  23 *	page->page_type: first object offset in a subpage of zspage
  24 *
  25 * Usage of struct page flags:
  26 *	PG_private: identifies the first component page
  27 *	PG_owner_priv_1: identifies the huge component page
  28 *
  29 */
  30
  31#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  32
  33/*
  34 * lock ordering:
  35 *	page_lock
  36 *	pool->lock
  37 *	zspage->lock
  38 */
  39
  40#include <linux/module.h>
  41#include <linux/kernel.h>
  42#include <linux/sched.h>
 
  43#include <linux/bitops.h>
  44#include <linux/errno.h>
  45#include <linux/highmem.h>
  46#include <linux/string.h>
  47#include <linux/slab.h>
  48#include <linux/pgtable.h>
  49#include <asm/tlbflush.h>
  50#include <linux/cpumask.h>
  51#include <linux/cpu.h>
  52#include <linux/vmalloc.h>
  53#include <linux/preempt.h>
  54#include <linux/spinlock.h>
  55#include <linux/shrinker.h>
  56#include <linux/types.h>
  57#include <linux/debugfs.h>
  58#include <linux/zsmalloc.h>
  59#include <linux/zpool.h>
 
 
  60#include <linux/migrate.h>
  61#include <linux/wait.h>
  62#include <linux/pagemap.h>
  63#include <linux/fs.h>
  64#include <linux/local_lock.h>
  65
  66#define ZSPAGE_MAGIC	0x58
  67
  68/*
  69 * This must be power of 2 and greater than or 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.
  73 */
  74#define ZS_ALIGN		8
  75
 
 
 
 
 
 
 
  76#define ZS_HANDLE_SIZE (sizeof(unsigned long))
  77
  78/*
  79 * Object location (<PFN>, <obj_idx>) is encoded as
  80 * a single (unsigned long) handle value.
  81 *
  82 * Note that object index <obj_idx> starts from 0.
  83 *
  84 * This is made more complicated by various memory models and PAE.
  85 */
  86
  87#ifndef MAX_POSSIBLE_PHYSMEM_BITS
  88#ifdef MAX_PHYSMEM_BITS
  89#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS
  90#else
  91/*
  92 * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just
  93 * be PAGE_SHIFT
  94 */
  95#define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG
  96#endif
  97#endif
  98
  99#define _PFN_BITS		(MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT)
 100
 101/*
 
 
 
 
 
 
 
 
 
 102 * Head in allocated object should have OBJ_ALLOCATED_TAG
 103 * to identify the object was allocated or not.
 104 * It's okay to add the status bit in the least bit because
 105 * header keeps handle which is 4byte-aligned address so we
 106 * have room for two bit at least.
 107 */
 108#define OBJ_ALLOCATED_TAG 1
 109
 110#define OBJ_TAG_BITS	1
 111#define OBJ_TAG_MASK	OBJ_ALLOCATED_TAG
 112
 113#define OBJ_INDEX_BITS	(BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
 114#define OBJ_INDEX_MASK	((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
 115
 116#define HUGE_BITS	1
 117#define FULLNESS_BITS	4
 118#define CLASS_BITS	8
 119#define ISOLATED_BITS	5
 120#define MAGIC_VAL_BITS	8
 121
 122#define MAX(a, b) ((a) >= (b) ? (a) : (b))
 123
 124#define ZS_MAX_PAGES_PER_ZSPAGE	(_AC(CONFIG_ZSMALLOC_CHAIN_SIZE, UL))
 125
 126/* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
 127#define ZS_MIN_ALLOC_SIZE \
 128	MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
 129/* each chunk includes extra space to keep handle */
 130#define ZS_MAX_ALLOC_SIZE	PAGE_SIZE
 131
 132/*
 133 * On systems with 4K page size, this gives 255 size classes! There is a
 134 * trader-off here:
 135 *  - Large number of size classes is potentially wasteful as free page are
 136 *    spread across these classes
 137 *  - Small number of size classes causes large internal fragmentation
 138 *  - Probably its better to use specific size classes (empirically
 139 *    determined). NOTE: all those class sizes must be set as multiple of
 140 *    ZS_ALIGN to make sure link_free itself never has to span 2 pages.
 141 *
 142 *  ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN
 143 *  (reason above)
 144 */
 145#define ZS_SIZE_CLASS_DELTA	(PAGE_SIZE >> CLASS_BITS)
 146#define ZS_SIZE_CLASSES	(DIV_ROUND_UP(ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE, \
 147				      ZS_SIZE_CLASS_DELTA) + 1)
 148
 149/*
 150 * Pages are distinguished by the ratio of used memory (that is the ratio
 151 * of ->inuse objects to all objects that page can store). For example,
 152 * INUSE_RATIO_10 means that the ratio of used objects is > 0% and <= 10%.
 153 *
 154 * The number of fullness groups is not random. It allows us to keep
 155 * difference between the least busy page in the group (minimum permitted
 156 * number of ->inuse objects) and the most busy page (maximum permitted
 157 * number of ->inuse objects) at a reasonable value.
 158 */
 159enum fullness_group {
 160	ZS_INUSE_RATIO_0,
 161	ZS_INUSE_RATIO_10,
 162	/* NOTE: 8 more fullness groups here */
 163	ZS_INUSE_RATIO_99       = 10,
 164	ZS_INUSE_RATIO_100,
 165	NR_FULLNESS_GROUPS,
 166};
 167
 168enum class_stat_type {
 169	/* NOTE: stats for 12 fullness groups here: from inuse 0 to 100 */
 170	ZS_OBJS_ALLOCATED       = NR_FULLNESS_GROUPS,
 171	ZS_OBJS_INUSE,
 172	NR_CLASS_STAT_TYPES,
 
 
 
 173};
 174
 175struct zs_size_stat {
 176	unsigned long objs[NR_CLASS_STAT_TYPES];
 177};
 178
 179#ifdef CONFIG_ZSMALLOC_STAT
 180static struct dentry *zs_stat_root;
 181#endif
 182
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 183static size_t huge_class_size;
 184
 185struct size_class {
 186	struct list_head fullness_list[NR_FULLNESS_GROUPS];
 
 187	/*
 188	 * Size of objects stored in this class. Must be multiple
 189	 * of ZS_ALIGN.
 190	 */
 191	int size;
 192	int objs_per_zspage;
 193	/* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
 194	int pages_per_zspage;
 195
 196	unsigned int index;
 197	struct zs_size_stat stats;
 198};
 199
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 200/*
 201 * Placed within free objects to form a singly linked list.
 202 * For every zspage, zspage->freeobj gives head of this list.
 203 *
 204 * This must be power of 2 and less than or equal to ZS_ALIGN
 205 */
 206struct link_free {
 207	union {
 208		/*
 209		 * Free object index;
 210		 * It's valid for non-allocated object
 211		 */
 212		unsigned long next;
 213		/*
 214		 * Handle of allocated object.
 215		 */
 216		unsigned long handle;
 217	};
 218};
 219
 220struct zs_pool {
 221	const char *name;
 222
 223	struct size_class *size_class[ZS_SIZE_CLASSES];
 224	struct kmem_cache *handle_cachep;
 225	struct kmem_cache *zspage_cachep;
 226
 227	atomic_long_t pages_allocated;
 228
 229	struct zs_pool_stats stats;
 230
 231	/* Compact classes */
 232	struct shrinker *shrinker;
 233
 234#ifdef CONFIG_ZSMALLOC_STAT
 235	struct dentry *stat_dentry;
 236#endif
 237#ifdef CONFIG_COMPACTION
 
 238	struct work_struct free_work;
 
 
 
 
 239#endif
 240	spinlock_t lock;
 241	atomic_t compaction_in_progress;
 242};
 243
 244struct zspage {
 245	struct {
 246		unsigned int huge:HUGE_BITS;
 247		unsigned int fullness:FULLNESS_BITS;
 248		unsigned int class:CLASS_BITS + 1;
 249		unsigned int isolated:ISOLATED_BITS;
 250		unsigned int magic:MAGIC_VAL_BITS;
 251	};
 252	unsigned int inuse;
 253	unsigned int freeobj;
 254	struct page *first_page;
 255	struct list_head list; /* fullness list */
 256	struct zs_pool *pool;
 257	rwlock_t lock;
 
 258};
 259
 260struct mapping_area {
 261	local_lock_t lock;
 
 
 262	char *vm_buf; /* copy buffer for objects that span pages */
 
 263	char *vm_addr; /* address of kmap_atomic()'ed pages */
 264	enum zs_mapmode vm_mm; /* mapping mode */
 265};
 266
 267/* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
 268static void SetZsHugePage(struct zspage *zspage)
 269{
 270	zspage->huge = 1;
 271}
 272
 273static bool ZsHugePage(struct zspage *zspage)
 274{
 275	return zspage->huge;
 276}
 277
 278static void migrate_lock_init(struct zspage *zspage);
 279static void migrate_read_lock(struct zspage *zspage);
 280static void migrate_read_unlock(struct zspage *zspage);
 281
 282#ifdef CONFIG_COMPACTION
 283static void migrate_write_lock(struct zspage *zspage);
 284static void migrate_write_lock_nested(struct zspage *zspage);
 285static void migrate_write_unlock(struct zspage *zspage);
 286static void kick_deferred_free(struct zs_pool *pool);
 287static void init_deferred_free(struct zs_pool *pool);
 288static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage);
 289#else
 290static void migrate_write_lock(struct zspage *zspage) {}
 291static void migrate_write_lock_nested(struct zspage *zspage) {}
 292static void migrate_write_unlock(struct zspage *zspage) {}
 
 
 
 
 293static void kick_deferred_free(struct zs_pool *pool) {}
 294static void init_deferred_free(struct zs_pool *pool) {}
 295static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage) {}
 296#endif
 297
 298static int create_cache(struct zs_pool *pool)
 299{
 300	pool->handle_cachep = kmem_cache_create("zs_handle", ZS_HANDLE_SIZE,
 301					0, 0, NULL);
 302	if (!pool->handle_cachep)
 303		return 1;
 304
 305	pool->zspage_cachep = kmem_cache_create("zspage", sizeof(struct zspage),
 306					0, 0, NULL);
 307	if (!pool->zspage_cachep) {
 308		kmem_cache_destroy(pool->handle_cachep);
 309		pool->handle_cachep = NULL;
 310		return 1;
 311	}
 312
 313	return 0;
 314}
 315
 316static void destroy_cache(struct zs_pool *pool)
 317{
 318	kmem_cache_destroy(pool->handle_cachep);
 319	kmem_cache_destroy(pool->zspage_cachep);
 320}
 321
 322static unsigned long cache_alloc_handle(struct zs_pool *pool, gfp_t gfp)
 323{
 324	return (unsigned long)kmem_cache_alloc(pool->handle_cachep,
 325			gfp & ~(__GFP_HIGHMEM|__GFP_MOVABLE));
 326}
 327
 328static void cache_free_handle(struct zs_pool *pool, unsigned long handle)
 329{
 330	kmem_cache_free(pool->handle_cachep, (void *)handle);
 331}
 332
 333static struct zspage *cache_alloc_zspage(struct zs_pool *pool, gfp_t flags)
 334{
 335	return kmem_cache_zalloc(pool->zspage_cachep,
 336			flags & ~(__GFP_HIGHMEM|__GFP_MOVABLE));
 337}
 338
 339static void cache_free_zspage(struct zs_pool *pool, struct zspage *zspage)
 340{
 341	kmem_cache_free(pool->zspage_cachep, zspage);
 342}
 343
 344/* pool->lock(which owns the handle) synchronizes races */
 345static void record_obj(unsigned long handle, unsigned long obj)
 346{
 347	*(unsigned long *)handle = obj;
 
 
 
 
 
 348}
 349
 350/* zpool driver */
 351
 352#ifdef CONFIG_ZPOOL
 353
 354static void *zs_zpool_create(const char *name, gfp_t gfp)
 
 
 355{
 356	/*
 357	 * Ignore global gfp flags: zs_malloc() may be invoked from
 358	 * different contexts and its caller must provide a valid
 359	 * gfp mask.
 360	 */
 361	return zs_create_pool(name);
 362}
 363
 364static void zs_zpool_destroy(void *pool)
 365{
 366	zs_destroy_pool(pool);
 367}
 368
 369static int zs_zpool_malloc(void *pool, size_t size, gfp_t gfp,
 370			unsigned long *handle)
 371{
 372	*handle = zs_malloc(pool, size, gfp);
 373
 374	if (IS_ERR_VALUE(*handle))
 375		return PTR_ERR((void *)*handle);
 376	return 0;
 377}
 378static void zs_zpool_free(void *pool, unsigned long handle)
 379{
 380	zs_free(pool, handle);
 381}
 382
 383static void *zs_zpool_map(void *pool, unsigned long handle,
 384			enum zpool_mapmode mm)
 385{
 386	enum zs_mapmode zs_mm;
 387
 388	switch (mm) {
 389	case ZPOOL_MM_RO:
 390		zs_mm = ZS_MM_RO;
 391		break;
 392	case ZPOOL_MM_WO:
 393		zs_mm = ZS_MM_WO;
 394		break;
 395	case ZPOOL_MM_RW:
 396	default:
 397		zs_mm = ZS_MM_RW;
 398		break;
 399	}
 400
 401	return zs_map_object(pool, handle, zs_mm);
 402}
 403static void zs_zpool_unmap(void *pool, unsigned long handle)
 404{
 405	zs_unmap_object(pool, handle);
 406}
 407
 408static u64 zs_zpool_total_size(void *pool)
 409{
 410	return zs_get_total_pages(pool) << PAGE_SHIFT;
 411}
 412
 413static struct zpool_driver zs_zpool_driver = {
 414	.type =			  "zsmalloc",
 415	.owner =		  THIS_MODULE,
 416	.create =		  zs_zpool_create,
 417	.destroy =		  zs_zpool_destroy,
 418	.malloc_support_movable = true,
 419	.malloc =		  zs_zpool_malloc,
 420	.free =			  zs_zpool_free,
 421	.map =			  zs_zpool_map,
 422	.unmap =		  zs_zpool_unmap,
 423	.total_size =		  zs_zpool_total_size,
 424};
 425
 426MODULE_ALIAS("zpool-zsmalloc");
 427#endif /* CONFIG_ZPOOL */
 428
 429/* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
 430static DEFINE_PER_CPU(struct mapping_area, zs_map_area) = {
 431	.lock	= INIT_LOCAL_LOCK(lock),
 432};
 
 
 
 433
 434static __maybe_unused int is_first_page(struct page *page)
 435{
 436	return PagePrivate(page);
 437}
 438
 439/* Protected by pool->lock */
 440static inline int get_zspage_inuse(struct zspage *zspage)
 441{
 442	return zspage->inuse;
 443}
 444
 445
 446static inline void mod_zspage_inuse(struct zspage *zspage, int val)
 447{
 448	zspage->inuse += val;
 449}
 450
 451static inline struct page *get_first_page(struct zspage *zspage)
 452{
 453	struct page *first_page = zspage->first_page;
 454
 455	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
 456	return first_page;
 457}
 458
 459static inline unsigned int get_first_obj_offset(struct page *page)
 460{
 461	return page->page_type;
 462}
 463
 464static inline void set_first_obj_offset(struct page *page, unsigned int offset)
 465{
 466	page->page_type = offset;
 467}
 468
 469static inline unsigned int get_freeobj(struct zspage *zspage)
 470{
 471	return zspage->freeobj;
 472}
 473
 474static inline void set_freeobj(struct zspage *zspage, unsigned int obj)
 475{
 476	zspage->freeobj = obj;
 477}
 478
 479static void get_zspage_mapping(struct zspage *zspage,
 480			       unsigned int *class_idx,
 481			       int *fullness)
 482{
 483	BUG_ON(zspage->magic != ZSPAGE_MAGIC);
 484
 485	*fullness = zspage->fullness;
 486	*class_idx = zspage->class;
 487}
 488
 489static struct size_class *zspage_class(struct zs_pool *pool,
 490				       struct zspage *zspage)
 491{
 492	return pool->size_class[zspage->class];
 493}
 494
 495static void set_zspage_mapping(struct zspage *zspage,
 496			       unsigned int class_idx,
 497			       int fullness)
 498{
 499	zspage->class = class_idx;
 500	zspage->fullness = fullness;
 501}
 502
 503/*
 504 * zsmalloc divides the pool into various size classes where each
 505 * class maintains a list of zspages where each zspage is divided
 506 * into equal sized chunks. Each allocation falls into one of these
 507 * classes depending on its size. This function returns index of the
 508 * size class which has chunk size big enough to hold the given size.
 509 */
 510static int get_size_class_index(int size)
 511{
 512	int idx = 0;
 513
 514	if (likely(size > ZS_MIN_ALLOC_SIZE))
 515		idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE,
 516				ZS_SIZE_CLASS_DELTA);
 517
 518	return min_t(int, ZS_SIZE_CLASSES - 1, idx);
 519}
 520
 521static inline void class_stat_inc(struct size_class *class,
 
 522				int type, unsigned long cnt)
 523{
 524	class->stats.objs[type] += cnt;
 525}
 526
 527static inline void class_stat_dec(struct size_class *class,
 
 528				int type, unsigned long cnt)
 529{
 530	class->stats.objs[type] -= cnt;
 531}
 532
 533static inline unsigned long zs_stat_get(struct size_class *class, int type)
 
 
 534{
 535	return class->stats.objs[type];
 536}
 537
 538#ifdef CONFIG_ZSMALLOC_STAT
 539
 540static void __init zs_stat_init(void)
 541{
 542	if (!debugfs_initialized()) {
 543		pr_warn("debugfs not available, stat dir not created\n");
 544		return;
 545	}
 546
 547	zs_stat_root = debugfs_create_dir("zsmalloc", NULL);
 548}
 549
 550static void __exit zs_stat_exit(void)
 551{
 552	debugfs_remove_recursive(zs_stat_root);
 553}
 554
 555static unsigned long zs_can_compact(struct size_class *class);
 556
 557static int zs_stats_size_show(struct seq_file *s, void *v)
 558{
 559	int i, fg;
 560	struct zs_pool *pool = s->private;
 561	struct size_class *class;
 562	int objs_per_zspage;
 
 563	unsigned long obj_allocated, obj_used, pages_used, freeable;
 
 564	unsigned long total_objs = 0, total_used_objs = 0, total_pages = 0;
 565	unsigned long total_freeable = 0;
 566	unsigned long inuse_totals[NR_FULLNESS_GROUPS] = {0, };
 567
 568	seq_printf(s, " %5s %5s %9s %9s %9s %9s %9s %9s %9s %9s %9s %9s %9s %13s %10s %10s %16s %8s\n",
 569			"class", "size", "10%", "20%", "30%", "40%",
 570			"50%", "60%", "70%", "80%", "90%", "99%", "100%",
 571			"obj_allocated", "obj_used", "pages_used",
 572			"pages_per_zspage", "freeable");
 573
 574	for (i = 0; i < ZS_SIZE_CLASSES; i++) {
 575
 576		class = pool->size_class[i];
 577
 578		if (class->index != i)
 579			continue;
 580
 581		spin_lock(&pool->lock);
 582
 583		seq_printf(s, " %5u %5u ", i, class->size);
 584		for (fg = ZS_INUSE_RATIO_10; fg < NR_FULLNESS_GROUPS; fg++) {
 585			inuse_totals[fg] += zs_stat_get(class, fg);
 586			seq_printf(s, "%9lu ", zs_stat_get(class, fg));
 587		}
 588
 589		obj_allocated = zs_stat_get(class, ZS_OBJS_ALLOCATED);
 590		obj_used = zs_stat_get(class, ZS_OBJS_INUSE);
 591		freeable = zs_can_compact(class);
 592		spin_unlock(&pool->lock);
 593
 594		objs_per_zspage = class->objs_per_zspage;
 595		pages_used = obj_allocated / objs_per_zspage *
 596				class->pages_per_zspage;
 597
 598		seq_printf(s, "%13lu %10lu %10lu %16d %8lu\n",
 599			   obj_allocated, obj_used, pages_used,
 600			   class->pages_per_zspage, freeable);
 
 
 601
 
 
 602		total_objs += obj_allocated;
 603		total_used_objs += obj_used;
 604		total_pages += pages_used;
 605		total_freeable += freeable;
 606	}
 607
 608	seq_puts(s, "\n");
 609	seq_printf(s, " %5s %5s ", "Total", "");
 610
 611	for (fg = ZS_INUSE_RATIO_10; fg < NR_FULLNESS_GROUPS; fg++)
 612		seq_printf(s, "%9lu ", inuse_totals[fg]);
 613
 614	seq_printf(s, "%13lu %10lu %10lu %16s %8lu\n",
 615		   total_objs, total_used_objs, total_pages, "",
 616		   total_freeable);
 617
 618	return 0;
 619}
 620DEFINE_SHOW_ATTRIBUTE(zs_stats_size);
 621
 622static void zs_pool_stat_create(struct zs_pool *pool, const char *name)
 623{
 624	if (!zs_stat_root) {
 625		pr_warn("no root stat dir, not creating <%s> stat dir\n", name);
 626		return;
 627	}
 628
 629	pool->stat_dentry = debugfs_create_dir(name, zs_stat_root);
 630
 631	debugfs_create_file("classes", S_IFREG | 0444, pool->stat_dentry, pool,
 632			    &zs_stats_size_fops);
 633}
 634
 635static void zs_pool_stat_destroy(struct zs_pool *pool)
 636{
 637	debugfs_remove_recursive(pool->stat_dentry);
 638}
 639
 640#else /* CONFIG_ZSMALLOC_STAT */
 641static void __init zs_stat_init(void)
 642{
 643}
 644
 645static void __exit zs_stat_exit(void)
 646{
 647}
 648
 649static inline void zs_pool_stat_create(struct zs_pool *pool, const char *name)
 650{
 651}
 652
 653static inline void zs_pool_stat_destroy(struct zs_pool *pool)
 654{
 655}
 656#endif
 657
 658
 659/*
 660 * For each size class, zspages are divided into different groups
 661 * depending on their usage ratio. This function returns fullness
 
 
 662 * status of the given page.
 663 */
 664static int get_fullness_group(struct size_class *class, struct zspage *zspage)
 
 665{
 666	int inuse, objs_per_zspage, ratio;
 
 667
 668	inuse = get_zspage_inuse(zspage);
 669	objs_per_zspage = class->objs_per_zspage;
 670
 671	if (inuse == 0)
 672		return ZS_INUSE_RATIO_0;
 673	if (inuse == objs_per_zspage)
 674		return ZS_INUSE_RATIO_100;
 
 
 
 
 675
 676	ratio = 100 * inuse / objs_per_zspage;
 677	/*
 678	 * Take integer division into consideration: a page with one inuse
 679	 * object out of 127 possible, will end up having 0 usage ratio,
 680	 * which is wrong as it belongs in ZS_INUSE_RATIO_10 fullness group.
 681	 */
 682	return ratio / 10 + 1;
 683}
 684
 685/*
 686 * Each size class maintains various freelists and zspages are assigned
 687 * to one of these freelists based on the number of live objects they
 688 * have. This functions inserts the given zspage into the freelist
 689 * identified by <class, fullness_group>.
 690 */
 691static void insert_zspage(struct size_class *class,
 692				struct zspage *zspage,
 693				int fullness)
 694{
 695	class_stat_inc(class, fullness, 1);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 696	list_add(&zspage->list, &class->fullness_list[fullness]);
 697}
 698
 699/*
 700 * This function removes the given zspage from the freelist identified
 701 * by <class, fullness_group>.
 702 */
 703static void remove_zspage(struct size_class *class,
 704				struct zspage *zspage,
 705				int fullness)
 706{
 707	VM_BUG_ON(list_empty(&class->fullness_list[fullness]));
 
 708
 709	list_del_init(&zspage->list);
 710	class_stat_dec(class, fullness, 1);
 711}
 712
 713/*
 714 * Each size class maintains zspages in different fullness groups depending
 715 * on the number of live objects they contain. When allocating or freeing
 716 * objects, the fullness status of the page can change, for instance, from
 717 * INUSE_RATIO_80 to INUSE_RATIO_70 when freeing an object. This function
 718 * checks if such a status change has occurred for the given page and
 719 * accordingly moves the page from the list of the old fullness group to that
 720 * of the new fullness group.
 721 */
 722static int fix_fullness_group(struct size_class *class, struct zspage *zspage)
 
 723{
 724	int class_idx;
 725	int currfg, newfg;
 726
 727	get_zspage_mapping(zspage, &class_idx, &currfg);
 728	newfg = get_fullness_group(class, zspage);
 729	if (newfg == currfg)
 730		goto out;
 731
 732	remove_zspage(class, zspage, currfg);
 733	insert_zspage(class, zspage, newfg);
 
 
 
 734	set_zspage_mapping(zspage, class_idx, newfg);
 
 735out:
 736	return newfg;
 737}
 738
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 739static struct zspage *get_zspage(struct page *page)
 740{
 741	struct zspage *zspage = (struct zspage *)page_private(page);
 742
 743	BUG_ON(zspage->magic != ZSPAGE_MAGIC);
 744	return zspage;
 745}
 746
 747static struct page *get_next_page(struct page *page)
 748{
 749	struct zspage *zspage = get_zspage(page);
 750
 751	if (unlikely(ZsHugePage(zspage)))
 752		return NULL;
 753
 754	return (struct page *)page->index;
 755}
 756
 757/**
 758 * obj_to_location - get (<page>, <obj_idx>) from encoded object value
 759 * @obj: the encoded object value
 760 * @page: page object resides in zspage
 761 * @obj_idx: object index
 762 */
 763static void obj_to_location(unsigned long obj, struct page **page,
 764				unsigned int *obj_idx)
 765{
 766	obj >>= OBJ_TAG_BITS;
 767	*page = pfn_to_page(obj >> OBJ_INDEX_BITS);
 768	*obj_idx = (obj & OBJ_INDEX_MASK);
 769}
 770
 771static void obj_to_page(unsigned long obj, struct page **page)
 772{
 773	obj >>= OBJ_TAG_BITS;
 774	*page = pfn_to_page(obj >> OBJ_INDEX_BITS);
 775}
 776
 777/**
 778 * location_to_obj - get obj value encoded from (<page>, <obj_idx>)
 779 * @page: page object resides in zspage
 780 * @obj_idx: object index
 781 */
 782static unsigned long location_to_obj(struct page *page, unsigned int obj_idx)
 783{
 784	unsigned long obj;
 785
 786	obj = page_to_pfn(page) << OBJ_INDEX_BITS;
 787	obj |= obj_idx & OBJ_INDEX_MASK;
 788	obj <<= OBJ_TAG_BITS;
 789
 790	return obj;
 791}
 792
 793static unsigned long handle_to_obj(unsigned long handle)
 794{
 795	return *(unsigned long *)handle;
 796}
 797
 798static inline bool obj_allocated(struct page *page, void *obj,
 799				 unsigned long *phandle)
 800{
 801	unsigned long handle;
 802	struct zspage *zspage = get_zspage(page);
 803
 804	if (unlikely(ZsHugePage(zspage))) {
 805		VM_BUG_ON_PAGE(!is_first_page(page), page);
 806		handle = page->index;
 807	} else
 808		handle = *(unsigned long *)obj;
 
 809
 810	if (!(handle & OBJ_ALLOCATED_TAG))
 811		return false;
 
 
 812
 813	/* Clear all tags before returning the handle */
 814	*phandle = handle & ~OBJ_TAG_MASK;
 815	return true;
 
 
 
 
 
 
 
 
 
 
 816}
 817
 818static void reset_page(struct page *page)
 819{
 820	__ClearPageMovable(page);
 821	ClearPagePrivate(page);
 822	set_page_private(page, 0);
 823	page_mapcount_reset(page);
 824	page->index = 0;
 
 825}
 826
 827static int trylock_zspage(struct zspage *zspage)
 828{
 829	struct page *cursor, *fail;
 830
 831	for (cursor = get_first_page(zspage); cursor != NULL; cursor =
 832					get_next_page(cursor)) {
 833		if (!trylock_page(cursor)) {
 834			fail = cursor;
 835			goto unlock;
 836		}
 837	}
 838
 839	return 1;
 840unlock:
 841	for (cursor = get_first_page(zspage); cursor != fail; cursor =
 842					get_next_page(cursor))
 843		unlock_page(cursor);
 844
 845	return 0;
 846}
 847
 848static void __free_zspage(struct zs_pool *pool, struct size_class *class,
 849				struct zspage *zspage)
 850{
 851	struct page *page, *next;
 852	int fg;
 853	unsigned int class_idx;
 854
 855	get_zspage_mapping(zspage, &class_idx, &fg);
 856
 857	assert_spin_locked(&pool->lock);
 858
 859	VM_BUG_ON(get_zspage_inuse(zspage));
 860	VM_BUG_ON(fg != ZS_INUSE_RATIO_0);
 861
 862	next = page = get_first_page(zspage);
 863	do {
 864		VM_BUG_ON_PAGE(!PageLocked(page), page);
 865		next = get_next_page(page);
 866		reset_page(page);
 867		unlock_page(page);
 868		dec_zone_page_state(page, NR_ZSPAGES);
 869		put_page(page);
 870		page = next;
 871	} while (page != NULL);
 872
 873	cache_free_zspage(pool, zspage);
 874
 875	class_stat_dec(class, ZS_OBJS_ALLOCATED, class->objs_per_zspage);
 876	atomic_long_sub(class->pages_per_zspage, &pool->pages_allocated);
 
 877}
 878
 879static void free_zspage(struct zs_pool *pool, struct size_class *class,
 880				struct zspage *zspage)
 881{
 882	VM_BUG_ON(get_zspage_inuse(zspage));
 883	VM_BUG_ON(list_empty(&zspage->list));
 884
 885	/*
 886	 * Since zs_free couldn't be sleepable, this function cannot call
 887	 * lock_page. The page locks trylock_zspage got will be released
 888	 * by __free_zspage.
 889	 */
 890	if (!trylock_zspage(zspage)) {
 891		kick_deferred_free(pool);
 892		return;
 893	}
 894
 895	remove_zspage(class, zspage, ZS_INUSE_RATIO_0);
 896	__free_zspage(pool, class, zspage);
 897}
 898
 899/* Initialize a newly allocated zspage */
 900static void init_zspage(struct size_class *class, struct zspage *zspage)
 901{
 902	unsigned int freeobj = 1;
 903	unsigned long off = 0;
 904	struct page *page = get_first_page(zspage);
 905
 906	while (page) {
 907		struct page *next_page;
 908		struct link_free *link;
 909		void *vaddr;
 910
 911		set_first_obj_offset(page, off);
 912
 913		vaddr = kmap_atomic(page);
 914		link = (struct link_free *)vaddr + off / sizeof(*link);
 915
 916		while ((off += class->size) < PAGE_SIZE) {
 917			link->next = freeobj++ << OBJ_TAG_BITS;
 918			link += class->size / sizeof(*link);
 919		}
 920
 921		/*
 922		 * We now come to the last (full or partial) object on this
 923		 * page, which must point to the first object on the next
 924		 * page (if present)
 925		 */
 926		next_page = get_next_page(page);
 927		if (next_page) {
 928			link->next = freeobj++ << OBJ_TAG_BITS;
 929		} else {
 930			/*
 931			 * Reset OBJ_TAG_BITS bit to last link to tell
 932			 * whether it's allocated object or not.
 933			 */
 934			link->next = -1UL << OBJ_TAG_BITS;
 935		}
 936		kunmap_atomic(vaddr);
 937		page = next_page;
 938		off %= PAGE_SIZE;
 939	}
 940
 941	set_freeobj(zspage, 0);
 942}
 943
 944static void create_page_chain(struct size_class *class, struct zspage *zspage,
 945				struct page *pages[])
 946{
 947	int i;
 948	struct page *page;
 949	struct page *prev_page = NULL;
 950	int nr_pages = class->pages_per_zspage;
 951
 952	/*
 953	 * Allocate individual pages and link them together as:
 954	 * 1. all pages are linked together using page->index
 955	 * 2. each sub-page point to zspage using page->private
 956	 *
 957	 * we set PG_private to identify the first page (i.e. no other sub-page
 958	 * has this flag set).
 959	 */
 960	for (i = 0; i < nr_pages; i++) {
 961		page = pages[i];
 962		set_page_private(page, (unsigned long)zspage);
 963		page->index = 0;
 964		if (i == 0) {
 965			zspage->first_page = page;
 966			SetPagePrivate(page);
 967			if (unlikely(class->objs_per_zspage == 1 &&
 968					class->pages_per_zspage == 1))
 969				SetZsHugePage(zspage);
 970		} else {
 971			prev_page->index = (unsigned long)page;
 972		}
 973		prev_page = page;
 974	}
 975}
 976
 977/*
 978 * Allocate a zspage for the given size class
 979 */
 980static struct zspage *alloc_zspage(struct zs_pool *pool,
 981					struct size_class *class,
 982					gfp_t gfp)
 983{
 984	int i;
 985	struct page *pages[ZS_MAX_PAGES_PER_ZSPAGE];
 986	struct zspage *zspage = cache_alloc_zspage(pool, gfp);
 987
 988	if (!zspage)
 989		return NULL;
 990
 
 991	zspage->magic = ZSPAGE_MAGIC;
 992	migrate_lock_init(zspage);
 993
 994	for (i = 0; i < class->pages_per_zspage; i++) {
 995		struct page *page;
 996
 997		page = alloc_page(gfp);
 998		if (!page) {
 999			while (--i >= 0) {
1000				dec_zone_page_state(pages[i], NR_ZSPAGES);
1001				__free_page(pages[i]);
1002			}
1003			cache_free_zspage(pool, zspage);
1004			return NULL;
1005		}
1006
1007		inc_zone_page_state(page, NR_ZSPAGES);
1008		pages[i] = page;
1009	}
1010
1011	create_page_chain(class, zspage, pages);
1012	init_zspage(class, zspage);
1013	zspage->pool = pool;
1014
1015	return zspage;
1016}
1017
1018static struct zspage *find_get_zspage(struct size_class *class)
1019{
1020	int i;
1021	struct zspage *zspage;
1022
1023	for (i = ZS_INUSE_RATIO_99; i >= ZS_INUSE_RATIO_0; i--) {
1024		zspage = list_first_entry_or_null(&class->fullness_list[i],
1025						  struct zspage, list);
1026		if (zspage)
1027			break;
1028	}
1029
1030	return zspage;
1031}
1032
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1033static inline int __zs_cpu_up(struct mapping_area *area)
1034{
1035	/*
1036	 * Make sure we don't leak memory if a cpu UP notification
1037	 * and zs_init() race and both call zs_cpu_up() on the same cpu
1038	 */
1039	if (area->vm_buf)
1040		return 0;
1041	area->vm_buf = kmalloc(ZS_MAX_ALLOC_SIZE, GFP_KERNEL);
1042	if (!area->vm_buf)
1043		return -ENOMEM;
1044	return 0;
1045}
1046
1047static inline void __zs_cpu_down(struct mapping_area *area)
1048{
1049	kfree(area->vm_buf);
1050	area->vm_buf = NULL;
1051}
1052
1053static void *__zs_map_object(struct mapping_area *area,
1054			struct page *pages[2], int off, int size)
1055{
1056	int sizes[2];
1057	void *addr;
1058	char *buf = area->vm_buf;
1059
1060	/* disable page faults to match kmap_atomic() return conditions */
1061	pagefault_disable();
1062
1063	/* no read fastpath */
1064	if (area->vm_mm == ZS_MM_WO)
1065		goto out;
1066
1067	sizes[0] = PAGE_SIZE - off;
1068	sizes[1] = size - sizes[0];
1069
1070	/* copy object to per-cpu buffer */
1071	addr = kmap_atomic(pages[0]);
1072	memcpy(buf, addr + off, sizes[0]);
1073	kunmap_atomic(addr);
1074	addr = kmap_atomic(pages[1]);
1075	memcpy(buf + sizes[0], addr, sizes[1]);
1076	kunmap_atomic(addr);
1077out:
1078	return area->vm_buf;
1079}
1080
1081static void __zs_unmap_object(struct mapping_area *area,
1082			struct page *pages[2], int off, int size)
1083{
1084	int sizes[2];
1085	void *addr;
1086	char *buf;
1087
1088	/* no write fastpath */
1089	if (area->vm_mm == ZS_MM_RO)
1090		goto out;
1091
1092	buf = area->vm_buf;
1093	buf = buf + ZS_HANDLE_SIZE;
1094	size -= ZS_HANDLE_SIZE;
1095	off += ZS_HANDLE_SIZE;
1096
1097	sizes[0] = PAGE_SIZE - off;
1098	sizes[1] = size - sizes[0];
1099
1100	/* copy per-cpu buffer to object */
1101	addr = kmap_atomic(pages[0]);
1102	memcpy(addr + off, buf, sizes[0]);
1103	kunmap_atomic(addr);
1104	addr = kmap_atomic(pages[1]);
1105	memcpy(addr, buf + sizes[0], sizes[1]);
1106	kunmap_atomic(addr);
1107
1108out:
1109	/* enable page faults to match kunmap_atomic() return conditions */
1110	pagefault_enable();
1111}
1112
 
 
1113static int zs_cpu_prepare(unsigned int cpu)
1114{
1115	struct mapping_area *area;
1116
1117	area = &per_cpu(zs_map_area, cpu);
1118	return __zs_cpu_up(area);
1119}
1120
1121static int zs_cpu_dead(unsigned int cpu)
1122{
1123	struct mapping_area *area;
1124
1125	area = &per_cpu(zs_map_area, cpu);
1126	__zs_cpu_down(area);
1127	return 0;
1128}
1129
1130static bool can_merge(struct size_class *prev, int pages_per_zspage,
1131					int objs_per_zspage)
1132{
1133	if (prev->pages_per_zspage == pages_per_zspage &&
1134		prev->objs_per_zspage == objs_per_zspage)
1135		return true;
1136
1137	return false;
1138}
1139
1140static bool zspage_full(struct size_class *class, struct zspage *zspage)
1141{
1142	return get_zspage_inuse(zspage) == class->objs_per_zspage;
1143}
1144
1145static bool zspage_empty(struct zspage *zspage)
1146{
1147	return get_zspage_inuse(zspage) == 0;
1148}
1149
1150/**
1151 * zs_lookup_class_index() - Returns index of the zsmalloc &size_class
1152 * that hold objects of the provided size.
1153 * @pool: zsmalloc pool to use
1154 * @size: object size
1155 *
1156 * Context: Any context.
1157 *
1158 * Return: the index of the zsmalloc &size_class that hold objects of the
1159 * provided size.
1160 */
1161unsigned int zs_lookup_class_index(struct zs_pool *pool, unsigned int size)
1162{
1163	struct size_class *class;
1164
1165	class = pool->size_class[get_size_class_index(size)];
1166
1167	return class->index;
1168}
1169EXPORT_SYMBOL_GPL(zs_lookup_class_index);
1170
1171unsigned long zs_get_total_pages(struct zs_pool *pool)
1172{
1173	return atomic_long_read(&pool->pages_allocated);
1174}
1175EXPORT_SYMBOL_GPL(zs_get_total_pages);
1176
1177/**
1178 * zs_map_object - get address of allocated object from handle.
1179 * @pool: pool from which the object was allocated
1180 * @handle: handle returned from zs_malloc
1181 * @mm: mapping mode to use
1182 *
1183 * Before using an object allocated from zs_malloc, it must be mapped using
1184 * this function. When done with the object, it must be unmapped using
1185 * zs_unmap_object.
1186 *
1187 * Only one object can be mapped per cpu at a time. There is no protection
1188 * against nested mappings.
1189 *
1190 * This function returns with preemption and page faults disabled.
1191 */
1192void *zs_map_object(struct zs_pool *pool, unsigned long handle,
1193			enum zs_mapmode mm)
1194{
1195	struct zspage *zspage;
1196	struct page *page;
1197	unsigned long obj, off;
1198	unsigned int obj_idx;
1199
 
 
1200	struct size_class *class;
1201	struct mapping_area *area;
1202	struct page *pages[2];
1203	void *ret;
1204
1205	/*
1206	 * Because we use per-cpu mapping areas shared among the
1207	 * pools/users, we can't allow mapping in interrupt context
1208	 * because it can corrupt another users mappings.
1209	 */
1210	BUG_ON(in_interrupt());
1211
1212	/* It guarantees it can get zspage from handle safely */
1213	spin_lock(&pool->lock);
 
1214	obj = handle_to_obj(handle);
1215	obj_to_location(obj, &page, &obj_idx);
1216	zspage = get_zspage(page);
1217
1218	/*
1219	 * migration cannot move any zpages in this zspage. Here, pool->lock
1220	 * is too heavy since callers would take some time until they calls
1221	 * zs_unmap_object API so delegate the locking from class to zspage
1222	 * which is smaller granularity.
1223	 */
1224	migrate_read_lock(zspage);
1225	spin_unlock(&pool->lock);
1226
1227	class = zspage_class(pool, zspage);
1228	off = offset_in_page(class->size * obj_idx);
 
1229
1230	local_lock(&zs_map_area.lock);
1231	area = this_cpu_ptr(&zs_map_area);
1232	area->vm_mm = mm;
1233	if (off + class->size <= PAGE_SIZE) {
1234		/* this object is contained entirely within a page */
1235		area->vm_addr = kmap_atomic(page);
1236		ret = area->vm_addr + off;
1237		goto out;
1238	}
1239
1240	/* this object spans two pages */
1241	pages[0] = page;
1242	pages[1] = get_next_page(page);
1243	BUG_ON(!pages[1]);
1244
1245	ret = __zs_map_object(area, pages, off, class->size);
1246out:
1247	if (likely(!ZsHugePage(zspage)))
1248		ret += ZS_HANDLE_SIZE;
1249
1250	return ret;
1251}
1252EXPORT_SYMBOL_GPL(zs_map_object);
1253
1254void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
1255{
1256	struct zspage *zspage;
1257	struct page *page;
1258	unsigned long obj, off;
1259	unsigned int obj_idx;
1260
 
 
1261	struct size_class *class;
1262	struct mapping_area *area;
1263
1264	obj = handle_to_obj(handle);
1265	obj_to_location(obj, &page, &obj_idx);
1266	zspage = get_zspage(page);
1267	class = zspage_class(pool, zspage);
1268	off = offset_in_page(class->size * obj_idx);
 
1269
1270	area = this_cpu_ptr(&zs_map_area);
1271	if (off + class->size <= PAGE_SIZE)
1272		kunmap_atomic(area->vm_addr);
1273	else {
1274		struct page *pages[2];
1275
1276		pages[0] = page;
1277		pages[1] = get_next_page(page);
1278		BUG_ON(!pages[1]);
1279
1280		__zs_unmap_object(area, pages, off, class->size);
1281	}
1282	local_unlock(&zs_map_area.lock);
1283
1284	migrate_read_unlock(zspage);
 
1285}
1286EXPORT_SYMBOL_GPL(zs_unmap_object);
1287
1288/**
1289 * zs_huge_class_size() - Returns the size (in bytes) of the first huge
1290 *                        zsmalloc &size_class.
1291 * @pool: zsmalloc pool to use
1292 *
1293 * The function returns the size of the first huge class - any object of equal
1294 * or bigger size will be stored in zspage consisting of a single physical
1295 * page.
1296 *
1297 * Context: Any context.
1298 *
1299 * Return: the size (in bytes) of the first huge zsmalloc &size_class.
1300 */
1301size_t zs_huge_class_size(struct zs_pool *pool)
1302{
1303	return huge_class_size;
1304}
1305EXPORT_SYMBOL_GPL(zs_huge_class_size);
1306
1307static unsigned long obj_malloc(struct zs_pool *pool,
1308				struct zspage *zspage, unsigned long handle)
1309{
1310	int i, nr_page, offset;
1311	unsigned long obj;
1312	struct link_free *link;
1313	struct size_class *class;
1314
1315	struct page *m_page;
1316	unsigned long m_offset;
1317	void *vaddr;
1318
1319	class = pool->size_class[zspage->class];
1320	handle |= OBJ_ALLOCATED_TAG;
1321	obj = get_freeobj(zspage);
1322
1323	offset = obj * class->size;
1324	nr_page = offset >> PAGE_SHIFT;
1325	m_offset = offset_in_page(offset);
1326	m_page = get_first_page(zspage);
1327
1328	for (i = 0; i < nr_page; i++)
1329		m_page = get_next_page(m_page);
1330
1331	vaddr = kmap_atomic(m_page);
1332	link = (struct link_free *)vaddr + m_offset / sizeof(*link);
1333	set_freeobj(zspage, link->next >> OBJ_TAG_BITS);
1334	if (likely(!ZsHugePage(zspage)))
1335		/* record handle in the header of allocated chunk */
1336		link->handle = handle;
1337	else
1338		/* record handle to page->index */
1339		zspage->first_page->index = handle;
1340
1341	kunmap_atomic(vaddr);
1342	mod_zspage_inuse(zspage, 1);
 
1343
1344	obj = location_to_obj(m_page, obj);
1345
1346	return obj;
1347}
1348
1349
1350/**
1351 * zs_malloc - Allocate block of given size from pool.
1352 * @pool: pool to allocate from
1353 * @size: size of block to allocate
1354 * @gfp: gfp flags when allocating object
1355 *
1356 * On success, handle to the allocated object is returned,
1357 * otherwise an ERR_PTR().
1358 * Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
1359 */
1360unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
1361{
1362	unsigned long handle, obj;
1363	struct size_class *class;
1364	int newfg;
1365	struct zspage *zspage;
1366
1367	if (unlikely(!size))
1368		return (unsigned long)ERR_PTR(-EINVAL);
1369
1370	if (unlikely(size > ZS_MAX_ALLOC_SIZE))
1371		return (unsigned long)ERR_PTR(-ENOSPC);
1372
1373	handle = cache_alloc_handle(pool, gfp);
1374	if (!handle)
1375		return (unsigned long)ERR_PTR(-ENOMEM);
1376
1377	/* extra space in chunk to keep the handle */
1378	size += ZS_HANDLE_SIZE;
1379	class = pool->size_class[get_size_class_index(size)];
1380
1381	/* pool->lock effectively protects the zpage migration */
1382	spin_lock(&pool->lock);
1383	zspage = find_get_zspage(class);
1384	if (likely(zspage)) {
1385		obj = obj_malloc(pool, zspage, handle);
1386		/* Now move the zspage to another fullness group, if required */
1387		fix_fullness_group(class, zspage);
1388		record_obj(handle, obj);
1389		class_stat_inc(class, ZS_OBJS_INUSE, 1);
1390
1391		goto out;
1392	}
1393
1394	spin_unlock(&pool->lock);
1395
1396	zspage = alloc_zspage(pool, class, gfp);
1397	if (!zspage) {
1398		cache_free_handle(pool, handle);
1399		return (unsigned long)ERR_PTR(-ENOMEM);
1400	}
1401
1402	spin_lock(&pool->lock);
1403	obj = obj_malloc(pool, zspage, handle);
1404	newfg = get_fullness_group(class, zspage);
1405	insert_zspage(class, zspage, newfg);
1406	set_zspage_mapping(zspage, class->index, newfg);
1407	record_obj(handle, obj);
1408	atomic_long_add(class->pages_per_zspage, &pool->pages_allocated);
1409	class_stat_inc(class, ZS_OBJS_ALLOCATED, class->objs_per_zspage);
1410	class_stat_inc(class, ZS_OBJS_INUSE, 1);
1411
1412	/* We completely set up zspage so mark them as movable */
1413	SetZsPageMovable(pool, zspage);
1414out:
1415	spin_unlock(&pool->lock);
1416
1417	return handle;
1418}
1419EXPORT_SYMBOL_GPL(zs_malloc);
1420
1421static void obj_free(int class_size, unsigned long obj)
1422{
1423	struct link_free *link;
1424	struct zspage *zspage;
1425	struct page *f_page;
1426	unsigned long f_offset;
1427	unsigned int f_objidx;
1428	void *vaddr;
1429
 
1430	obj_to_location(obj, &f_page, &f_objidx);
1431	f_offset = offset_in_page(class_size * f_objidx);
1432	zspage = get_zspage(f_page);
1433
1434	vaddr = kmap_atomic(f_page);
1435	link = (struct link_free *)(vaddr + f_offset);
1436
1437	/* Insert this object in containing zspage's freelist */
1438	if (likely(!ZsHugePage(zspage)))
1439		link->next = get_freeobj(zspage) << OBJ_TAG_BITS;
1440	else
1441		f_page->index = 0;
1442	set_freeobj(zspage, f_objidx);
1443
1444	kunmap_atomic(vaddr);
 
1445	mod_zspage_inuse(zspage, -1);
 
1446}
1447
1448void zs_free(struct zs_pool *pool, unsigned long handle)
1449{
1450	struct zspage *zspage;
1451	struct page *f_page;
1452	unsigned long obj;
 
 
1453	struct size_class *class;
1454	int fullness;
 
1455
1456	if (IS_ERR_OR_NULL((void *)handle))
1457		return;
1458
1459	/*
1460	 * The pool->lock protects the race with zpage's migration
1461	 * so it's safe to get the page from handle.
1462	 */
1463	spin_lock(&pool->lock);
1464	obj = handle_to_obj(handle);
1465	obj_to_page(obj, &f_page);
1466	zspage = get_zspage(f_page);
1467	class = zspage_class(pool, zspage);
1468
1469	class_stat_dec(class, ZS_OBJS_INUSE, 1);
1470	obj_free(class->size, obj);
 
 
1471
 
 
1472	fullness = fix_fullness_group(class, zspage);
1473	if (fullness == ZS_INUSE_RATIO_0)
 
 
 
 
 
 
 
 
1474		free_zspage(pool, class, zspage);
 
1475
1476	spin_unlock(&pool->lock);
 
1477	cache_free_handle(pool, handle);
1478}
1479EXPORT_SYMBOL_GPL(zs_free);
1480
1481static void zs_object_copy(struct size_class *class, unsigned long dst,
1482				unsigned long src)
1483{
1484	struct page *s_page, *d_page;
1485	unsigned int s_objidx, d_objidx;
1486	unsigned long s_off, d_off;
1487	void *s_addr, *d_addr;
1488	int s_size, d_size, size;
1489	int written = 0;
1490
1491	s_size = d_size = class->size;
1492
1493	obj_to_location(src, &s_page, &s_objidx);
1494	obj_to_location(dst, &d_page, &d_objidx);
1495
1496	s_off = offset_in_page(class->size * s_objidx);
1497	d_off = offset_in_page(class->size * d_objidx);
1498
1499	if (s_off + class->size > PAGE_SIZE)
1500		s_size = PAGE_SIZE - s_off;
1501
1502	if (d_off + class->size > PAGE_SIZE)
1503		d_size = PAGE_SIZE - d_off;
1504
1505	s_addr = kmap_atomic(s_page);
1506	d_addr = kmap_atomic(d_page);
1507
1508	while (1) {
1509		size = min(s_size, d_size);
1510		memcpy(d_addr + d_off, s_addr + s_off, size);
1511		written += size;
1512
1513		if (written == class->size)
1514			break;
1515
1516		s_off += size;
1517		s_size -= size;
1518		d_off += size;
1519		d_size -= size;
1520
1521		/*
1522		 * Calling kunmap_atomic(d_addr) is necessary. kunmap_atomic()
1523		 * calls must occurs in reverse order of calls to kmap_atomic().
1524		 * So, to call kunmap_atomic(s_addr) we should first call
1525		 * kunmap_atomic(d_addr). For more details see
1526		 * Documentation/mm/highmem.rst.
1527		 */
1528		if (s_off >= PAGE_SIZE) {
1529			kunmap_atomic(d_addr);
1530			kunmap_atomic(s_addr);
1531			s_page = get_next_page(s_page);
1532			s_addr = kmap_atomic(s_page);
1533			d_addr = kmap_atomic(d_page);
1534			s_size = class->size - written;
1535			s_off = 0;
1536		}
1537
1538		if (d_off >= PAGE_SIZE) {
1539			kunmap_atomic(d_addr);
1540			d_page = get_next_page(d_page);
1541			d_addr = kmap_atomic(d_page);
1542			d_size = class->size - written;
1543			d_off = 0;
1544		}
1545	}
1546
1547	kunmap_atomic(d_addr);
1548	kunmap_atomic(s_addr);
1549}
1550
1551/*
1552 * Find alloced object in zspage from index object and
1553 * return handle.
1554 */
1555static unsigned long find_alloced_obj(struct size_class *class,
1556				      struct page *page, int *obj_idx)
1557{
1558	unsigned int offset;
 
1559	int index = *obj_idx;
1560	unsigned long handle = 0;
1561	void *addr = kmap_atomic(page);
1562
1563	offset = get_first_obj_offset(page);
1564	offset += class->size * index;
1565
1566	while (offset < PAGE_SIZE) {
1567		if (obj_allocated(page, addr + offset, &handle))
1568			break;
 
 
 
 
 
1569
1570		offset += class->size;
1571		index++;
1572	}
1573
1574	kunmap_atomic(addr);
1575
1576	*obj_idx = index;
1577
1578	return handle;
1579}
1580
1581static void migrate_zspage(struct zs_pool *pool, struct zspage *src_zspage,
1582			   struct zspage *dst_zspage)
 
 
 
 
 
 
 
 
 
 
 
1583{
1584	unsigned long used_obj, free_obj;
1585	unsigned long handle;
1586	int obj_idx = 0;
1587	struct page *s_page = get_first_page(src_zspage);
1588	struct size_class *class = pool->size_class[src_zspage->class];
 
1589
1590	while (1) {
1591		handle = find_alloced_obj(class, s_page, &obj_idx);
1592		if (!handle) {
1593			s_page = get_next_page(s_page);
1594			if (!s_page)
1595				break;
1596			obj_idx = 0;
1597			continue;
1598		}
1599
 
 
 
 
 
 
 
1600		used_obj = handle_to_obj(handle);
1601		free_obj = obj_malloc(pool, dst_zspage, handle);
1602		zs_object_copy(class, free_obj, used_obj);
1603		obj_idx++;
 
 
 
 
 
 
 
1604		record_obj(handle, free_obj);
1605		obj_free(class->size, used_obj);
 
 
1606
1607		/* Stop if there is no more space */
1608		if (zspage_full(class, dst_zspage))
1609			break;
1610
1611		/* Stop if there are no more objects to migrate */
1612		if (zspage_empty(src_zspage))
1613			break;
1614	}
1615}
1616
1617static struct zspage *isolate_src_zspage(struct size_class *class)
1618{
 
1619	struct zspage *zspage;
1620	int fg;
1621
1622	for (fg = ZS_INUSE_RATIO_10; fg <= ZS_INUSE_RATIO_99; fg++) {
1623		zspage = list_first_entry_or_null(&class->fullness_list[fg],
1624						  struct zspage, list);
1625		if (zspage) {
1626			remove_zspage(class, zspage, fg);
1627			return zspage;
1628		}
1629	}
1630
1631	return zspage;
1632}
1633
1634static struct zspage *isolate_dst_zspage(struct size_class *class)
1635{
1636	struct zspage *zspage;
1637	int fg;
1638
1639	for (fg = ZS_INUSE_RATIO_99; fg >= ZS_INUSE_RATIO_10; fg--) {
1640		zspage = list_first_entry_or_null(&class->fullness_list[fg],
1641						  struct zspage, list);
1642		if (zspage) {
1643			remove_zspage(class, zspage, fg);
 
1644			return zspage;
1645		}
1646	}
1647
1648	return zspage;
1649}
1650
1651/*
1652 * putback_zspage - add @zspage into right class's fullness list
1653 * @class: destination class
1654 * @zspage: target page
1655 *
1656 * Return @zspage's fullness status
1657 */
1658static int putback_zspage(struct size_class *class, struct zspage *zspage)
 
1659{
1660	int fullness;
 
 
1661
1662	fullness = get_fullness_group(class, zspage);
1663	insert_zspage(class, zspage, fullness);
1664	set_zspage_mapping(zspage, class->index, fullness);
1665
1666	return fullness;
1667}
1668
1669#ifdef CONFIG_COMPACTION
1670/*
1671 * To prevent zspage destroy during migration, zspage freeing should
1672 * hold locks of all pages in the zspage.
1673 */
1674static void lock_zspage(struct zspage *zspage)
1675{
1676	struct page *curr_page, *page;
1677
1678	/*
1679	 * Pages we haven't locked yet can be migrated off the list while we're
1680	 * trying to lock them, so we need to be careful and only attempt to
1681	 * lock each page under migrate_read_lock(). Otherwise, the page we lock
1682	 * may no longer belong to the zspage. This means that we may wait for
1683	 * the wrong page to unlock, so we must take a reference to the page
1684	 * prior to waiting for it to unlock outside migrate_read_lock().
1685	 */
1686	while (1) {
1687		migrate_read_lock(zspage);
1688		page = get_first_page(zspage);
1689		if (trylock_page(page))
1690			break;
1691		get_page(page);
1692		migrate_read_unlock(zspage);
1693		wait_on_page_locked(page);
1694		put_page(page);
1695	}
1696
1697	curr_page = page;
1698	while ((page = get_next_page(curr_page))) {
1699		if (trylock_page(page)) {
1700			curr_page = page;
1701		} else {
1702			get_page(page);
1703			migrate_read_unlock(zspage);
1704			wait_on_page_locked(page);
1705			put_page(page);
1706			migrate_read_lock(zspage);
1707		}
1708	}
1709	migrate_read_unlock(zspage);
 
 
 
 
 
 
 
 
 
 
 
 
1710}
1711#endif /* CONFIG_COMPACTION */
1712
1713static void migrate_lock_init(struct zspage *zspage)
1714{
1715	rwlock_init(&zspage->lock);
1716}
1717
1718static void migrate_read_lock(struct zspage *zspage) __acquires(&zspage->lock)
1719{
1720	read_lock(&zspage->lock);
1721}
1722
1723static void migrate_read_unlock(struct zspage *zspage) __releases(&zspage->lock)
1724{
1725	read_unlock(&zspage->lock);
1726}
1727
1728#ifdef CONFIG_COMPACTION
1729static void migrate_write_lock(struct zspage *zspage)
1730{
1731	write_lock(&zspage->lock);
1732}
1733
1734static void migrate_write_lock_nested(struct zspage *zspage)
1735{
1736	write_lock_nested(&zspage->lock, SINGLE_DEPTH_NESTING);
1737}
1738
1739static void migrate_write_unlock(struct zspage *zspage)
1740{
1741	write_unlock(&zspage->lock);
1742}
1743
1744/* Number of isolated subpage for *page migration* in this zspage */
1745static void inc_zspage_isolation(struct zspage *zspage)
1746{
1747	zspage->isolated++;
1748}
1749
1750static void dec_zspage_isolation(struct zspage *zspage)
1751{
1752	VM_BUG_ON(zspage->isolated == 0);
1753	zspage->isolated--;
1754}
1755
1756static const struct movable_operations zsmalloc_mops;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1757
1758static void replace_sub_page(struct size_class *class, struct zspage *zspage,
1759				struct page *newpage, struct page *oldpage)
1760{
1761	struct page *page;
1762	struct page *pages[ZS_MAX_PAGES_PER_ZSPAGE] = {NULL, };
1763	int idx = 0;
1764
1765	page = get_first_page(zspage);
1766	do {
1767		if (page == oldpage)
1768			pages[idx] = newpage;
1769		else
1770			pages[idx] = page;
1771		idx++;
1772	} while ((page = get_next_page(page)) != NULL);
1773
1774	create_page_chain(class, zspage, pages);
1775	set_first_obj_offset(newpage, get_first_obj_offset(oldpage));
1776	if (unlikely(ZsHugePage(zspage)))
1777		newpage->index = oldpage->index;
1778	__SetPageMovable(newpage, &zsmalloc_mops);
1779}
1780
1781static bool zs_page_isolate(struct page *page, isolate_mode_t mode)
1782{
1783	struct zs_pool *pool;
 
 
 
1784	struct zspage *zspage;
 
1785
1786	/*
1787	 * Page is locked so zspage couldn't be destroyed. For detail, look at
1788	 * lock_zspage in free_zspage.
1789	 */
 
1790	VM_BUG_ON_PAGE(PageIsolated(page), page);
1791
1792	zspage = get_zspage(page);
1793	pool = zspage->pool;
1794	spin_lock(&pool->lock);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1795	inc_zspage_isolation(zspage);
1796	spin_unlock(&pool->lock);
1797
1798	return true;
1799}
1800
1801static int zs_page_migrate(struct page *newpage, struct page *page,
1802		enum migrate_mode mode)
1803{
1804	struct zs_pool *pool;
1805	struct size_class *class;
 
 
1806	struct zspage *zspage;
1807	struct page *dummy;
1808	void *s_addr, *d_addr, *addr;
1809	unsigned int offset;
1810	unsigned long handle;
1811	unsigned long old_obj, new_obj;
1812	unsigned int obj_idx;
 
1813
1814	/*
1815	 * We cannot support the _NO_COPY case here, because copy needs to
1816	 * happen under the zs lock, which does not work with
1817	 * MIGRATE_SYNC_NO_COPY workflow.
1818	 */
1819	if (mode == MIGRATE_SYNC_NO_COPY)
1820		return -EINVAL;
1821
 
1822	VM_BUG_ON_PAGE(!PageIsolated(page), page);
1823
1824	/* The page is locked, so this pointer must remain valid */
1825	zspage = get_zspage(page);
1826	pool = zspage->pool;
1827
1828	/*
1829	 * The pool's lock protects the race between zpage migration
1830	 * and zs_free.
1831	 */
1832	spin_lock(&pool->lock);
1833	class = zspage_class(pool, zspage);
1834
1835	/* the migrate_write_lock protects zpage access via zs_map_object */
1836	migrate_write_lock(zspage);
1837
 
 
1838	offset = get_first_obj_offset(page);
 
 
 
 
 
 
 
 
 
 
 
1839	s_addr = kmap_atomic(page);
 
 
 
 
 
 
 
 
 
1840
1841	/*
1842	 * Here, any user cannot access all objects in the zspage so let's move.
1843	 */
1844	d_addr = kmap_atomic(newpage);
1845	copy_page(d_addr, s_addr);
1846	kunmap_atomic(d_addr);
1847
1848	for (addr = s_addr + offset; addr < s_addr + PAGE_SIZE;
1849					addr += class->size) {
1850		if (obj_allocated(page, addr, &handle)) {
 
 
 
 
1851
1852			old_obj = handle_to_obj(handle);
1853			obj_to_location(old_obj, &dummy, &obj_idx);
1854			new_obj = (unsigned long)location_to_obj(newpage,
1855								obj_idx);
 
1856			record_obj(handle, new_obj);
1857		}
1858	}
1859	kunmap_atomic(s_addr);
1860
1861	replace_sub_page(class, zspage, newpage, page);
 
 
1862	dec_zspage_isolation(zspage);
 
1863	/*
1864	 * Since we complete the data copy and set up new zspage structure,
1865	 * it's okay to release the pool's lock.
1866	 */
1867	spin_unlock(&pool->lock);
1868	migrate_write_unlock(zspage);
 
 
 
 
 
 
 
 
1869
1870	get_page(newpage);
1871	if (page_zone(newpage) != page_zone(page)) {
1872		dec_zone_page_state(page, NR_ZSPAGES);
1873		inc_zone_page_state(newpage, NR_ZSPAGES);
1874	}
1875
1876	reset_page(page);
1877	put_page(page);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1878
1879	return MIGRATEPAGE_SUCCESS;
1880}
1881
1882static void zs_page_putback(struct page *page)
1883{
1884	struct zs_pool *pool;
 
 
 
 
1885	struct zspage *zspage;
1886
 
1887	VM_BUG_ON_PAGE(!PageIsolated(page), page);
1888
1889	zspage = get_zspage(page);
1890	pool = zspage->pool;
1891	spin_lock(&pool->lock);
 
 
 
 
1892	dec_zspage_isolation(zspage);
1893	spin_unlock(&pool->lock);
 
 
 
 
 
 
 
 
1894}
1895
1896static const struct movable_operations zsmalloc_mops = {
1897	.isolate_page = zs_page_isolate,
1898	.migrate_page = zs_page_migrate,
1899	.putback_page = zs_page_putback,
1900};
1901
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1902/*
1903 * Caller should hold page_lock of all pages in the zspage
1904 * In here, we cannot use zspage meta data.
1905 */
1906static void async_free_zspage(struct work_struct *work)
1907{
1908	int i;
1909	struct size_class *class;
1910	unsigned int class_idx;
1911	int fullness;
1912	struct zspage *zspage, *tmp;
1913	LIST_HEAD(free_pages);
1914	struct zs_pool *pool = container_of(work, struct zs_pool,
1915					free_work);
1916
1917	for (i = 0; i < ZS_SIZE_CLASSES; i++) {
1918		class = pool->size_class[i];
1919		if (class->index != i)
1920			continue;
1921
1922		spin_lock(&pool->lock);
1923		list_splice_init(&class->fullness_list[ZS_INUSE_RATIO_0],
1924				 &free_pages);
1925		spin_unlock(&pool->lock);
1926	}
1927
 
1928	list_for_each_entry_safe(zspage, tmp, &free_pages, list) {
1929		list_del(&zspage->list);
1930		lock_zspage(zspage);
1931
1932		get_zspage_mapping(zspage, &class_idx, &fullness);
1933		VM_BUG_ON(fullness != ZS_INUSE_RATIO_0);
1934		class = pool->size_class[class_idx];
1935		spin_lock(&pool->lock);
1936		__free_zspage(pool, class, zspage);
1937		spin_unlock(&pool->lock);
1938	}
1939};
1940
1941static void kick_deferred_free(struct zs_pool *pool)
1942{
1943	schedule_work(&pool->free_work);
1944}
1945
1946static void zs_flush_migration(struct zs_pool *pool)
1947{
1948	flush_work(&pool->free_work);
1949}
1950
1951static void init_deferred_free(struct zs_pool *pool)
1952{
1953	INIT_WORK(&pool->free_work, async_free_zspage);
1954}
1955
1956static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage)
1957{
1958	struct page *page = get_first_page(zspage);
1959
1960	do {
1961		WARN_ON(!trylock_page(page));
1962		__SetPageMovable(page, &zsmalloc_mops);
1963		unlock_page(page);
1964	} while ((page = get_next_page(page)) != NULL);
1965}
1966#else
1967static inline void zs_flush_migration(struct zs_pool *pool) { }
1968#endif
1969
1970/*
1971 *
1972 * Based on the number of unused allocated objects calculate
1973 * and return the number of pages that we can free.
1974 */
1975static unsigned long zs_can_compact(struct size_class *class)
1976{
1977	unsigned long obj_wasted;
1978	unsigned long obj_allocated = zs_stat_get(class, ZS_OBJS_ALLOCATED);
1979	unsigned long obj_used = zs_stat_get(class, ZS_OBJS_INUSE);
1980
1981	if (obj_allocated <= obj_used)
1982		return 0;
1983
1984	obj_wasted = obj_allocated - obj_used;
1985	obj_wasted /= class->objs_per_zspage;
1986
1987	return obj_wasted * class->pages_per_zspage;
1988}
1989
1990static unsigned long __zs_compact(struct zs_pool *pool,
1991				  struct size_class *class)
1992{
1993	struct zspage *src_zspage = NULL;
 
1994	struct zspage *dst_zspage = NULL;
1995	unsigned long pages_freed = 0;
1996
1997	/*
1998	 * protect the race between zpage migration and zs_free
1999	 * as well as zpage allocation/free
2000	 */
2001	spin_lock(&pool->lock);
2002	while (zs_can_compact(class)) {
2003		int fg;
2004
2005		if (!dst_zspage) {
2006			dst_zspage = isolate_dst_zspage(class);
2007			if (!dst_zspage)
2008				break;
2009			migrate_write_lock(dst_zspage);
2010		}
2011
2012		src_zspage = isolate_src_zspage(class);
2013		if (!src_zspage)
2014			break;
2015
2016		migrate_write_lock_nested(src_zspage);
 
2017
2018		migrate_zspage(pool, src_zspage, dst_zspage);
2019		fg = putback_zspage(class, src_zspage);
2020		migrate_write_unlock(src_zspage);
 
 
 
 
 
2021
2022		if (fg == ZS_INUSE_RATIO_0) {
2023			free_zspage(pool, class, src_zspage);
2024			pages_freed += class->pages_per_zspage;
2025		}
2026		src_zspage = NULL;
2027
2028		if (get_fullness_group(class, dst_zspage) == ZS_INUSE_RATIO_100
2029		    || spin_is_contended(&pool->lock)) {
2030			putback_zspage(class, dst_zspage);
2031			migrate_write_unlock(dst_zspage);
2032			dst_zspage = NULL;
2033
2034			spin_unlock(&pool->lock);
2035			cond_resched();
2036			spin_lock(&pool->lock);
 
2037		}
 
 
 
2038	}
2039
2040	if (src_zspage) {
2041		putback_zspage(class, src_zspage);
2042		migrate_write_unlock(src_zspage);
2043	}
2044
2045	if (dst_zspage) {
2046		putback_zspage(class, dst_zspage);
2047		migrate_write_unlock(dst_zspage);
2048	}
2049	spin_unlock(&pool->lock);
2050
2051	return pages_freed;
2052}
2053
2054unsigned long zs_compact(struct zs_pool *pool)
2055{
2056	int i;
2057	struct size_class *class;
2058	unsigned long pages_freed = 0;
2059
2060	/*
2061	 * Pool compaction is performed under pool->lock so it is basically
2062	 * single-threaded. Having more than one thread in __zs_compact()
2063	 * will increase pool->lock contention, which will impact other
2064	 * zsmalloc operations that need pool->lock.
2065	 */
2066	if (atomic_xchg(&pool->compaction_in_progress, 1))
2067		return 0;
2068
2069	for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
2070		class = pool->size_class[i];
 
 
2071		if (class->index != i)
2072			continue;
2073		pages_freed += __zs_compact(pool, class);
2074	}
2075	atomic_long_add(pages_freed, &pool->stats.pages_compacted);
2076	atomic_set(&pool->compaction_in_progress, 0);
2077
2078	return pages_freed;
2079}
2080EXPORT_SYMBOL_GPL(zs_compact);
2081
2082void zs_pool_stats(struct zs_pool *pool, struct zs_pool_stats *stats)
2083{
2084	memcpy(stats, &pool->stats, sizeof(struct zs_pool_stats));
2085}
2086EXPORT_SYMBOL_GPL(zs_pool_stats);
2087
2088static unsigned long zs_shrinker_scan(struct shrinker *shrinker,
2089		struct shrink_control *sc)
2090{
2091	unsigned long pages_freed;
2092	struct zs_pool *pool = shrinker->private_data;
 
2093
 
2094	/*
2095	 * Compact classes and calculate compaction delta.
2096	 * Can run concurrently with a manually triggered
2097	 * (by user) compaction.
2098	 */
2099	pages_freed = zs_compact(pool);
2100
2101	return pages_freed ? pages_freed : SHRINK_STOP;
2102}
2103
2104static unsigned long zs_shrinker_count(struct shrinker *shrinker,
2105		struct shrink_control *sc)
2106{
2107	int i;
2108	struct size_class *class;
2109	unsigned long pages_to_free = 0;
2110	struct zs_pool *pool = shrinker->private_data;
 
2111
2112	for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
2113		class = pool->size_class[i];
 
 
2114		if (class->index != i)
2115			continue;
2116
2117		pages_to_free += zs_can_compact(class);
2118	}
2119
2120	return pages_to_free;
2121}
2122
2123static void zs_unregister_shrinker(struct zs_pool *pool)
2124{
2125	shrinker_free(pool->shrinker);
2126}
2127
2128static int zs_register_shrinker(struct zs_pool *pool)
2129{
2130	pool->shrinker = shrinker_alloc(0, "mm-zspool:%s", pool->name);
2131	if (!pool->shrinker)
2132		return -ENOMEM;
 
2133
2134	pool->shrinker->scan_objects = zs_shrinker_scan;
2135	pool->shrinker->count_objects = zs_shrinker_count;
2136	pool->shrinker->batch = 0;
2137	pool->shrinker->private_data = pool;
2138
2139	shrinker_register(pool->shrinker);
2140
2141	return 0;
2142}
2143
2144static int calculate_zspage_chain_size(int class_size)
2145{
2146	int i, min_waste = INT_MAX;
2147	int chain_size = 1;
2148
2149	if (is_power_of_2(class_size))
2150		return chain_size;
2151
2152	for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) {
2153		int waste;
2154
2155		waste = (i * PAGE_SIZE) % class_size;
2156		if (waste < min_waste) {
2157			min_waste = waste;
2158			chain_size = i;
2159		}
2160	}
2161
2162	return chain_size;
2163}
2164
2165/**
2166 * zs_create_pool - Creates an allocation pool to work from.
2167 * @name: pool name to be created
2168 *
2169 * This function must be called before anything when using
2170 * the zsmalloc allocator.
2171 *
2172 * On success, a pointer to the newly created pool is returned,
2173 * otherwise NULL.
2174 */
2175struct zs_pool *zs_create_pool(const char *name)
2176{
2177	int i;
2178	struct zs_pool *pool;
2179	struct size_class *prev_class = NULL;
2180
2181	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
2182	if (!pool)
2183		return NULL;
2184
2185	init_deferred_free(pool);
2186	spin_lock_init(&pool->lock);
2187	atomic_set(&pool->compaction_in_progress, 0);
2188
2189	pool->name = kstrdup(name, GFP_KERNEL);
2190	if (!pool->name)
2191		goto err;
2192
 
 
 
 
2193	if (create_cache(pool))
2194		goto err;
2195
2196	/*
2197	 * Iterate reversely, because, size of size_class that we want to use
2198	 * for merging should be larger or equal to current size.
2199	 */
2200	for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
2201		int size;
2202		int pages_per_zspage;
2203		int objs_per_zspage;
2204		struct size_class *class;
2205		int fullness;
2206
2207		size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA;
2208		if (size > ZS_MAX_ALLOC_SIZE)
2209			size = ZS_MAX_ALLOC_SIZE;
2210		pages_per_zspage = calculate_zspage_chain_size(size);
2211		objs_per_zspage = pages_per_zspage * PAGE_SIZE / size;
2212
2213		/*
2214		 * We iterate from biggest down to smallest classes,
2215		 * so huge_class_size holds the size of the first huge
2216		 * class. Any object bigger than or equal to that will
2217		 * endup in the huge class.
2218		 */
2219		if (pages_per_zspage != 1 && objs_per_zspage != 1 &&
2220				!huge_class_size) {
2221			huge_class_size = size;
2222			/*
2223			 * The object uses ZS_HANDLE_SIZE bytes to store the
2224			 * handle. We need to subtract it, because zs_malloc()
2225			 * unconditionally adds handle size before it performs
2226			 * size class search - so object may be smaller than
2227			 * huge class size, yet it still can end up in the huge
2228			 * class because it grows by ZS_HANDLE_SIZE extra bytes
2229			 * right before class lookup.
2230			 */
2231			huge_class_size -= (ZS_HANDLE_SIZE - 1);
2232		}
2233
2234		/*
2235		 * size_class is used for normal zsmalloc operation such
2236		 * as alloc/free for that size. Although it is natural that we
2237		 * have one size_class for each size, there is a chance that we
2238		 * can get more memory utilization if we use one size_class for
2239		 * many different sizes whose size_class have same
2240		 * characteristics. So, we makes size_class point to
2241		 * previous size_class if possible.
2242		 */
2243		if (prev_class) {
2244			if (can_merge(prev_class, pages_per_zspage, objs_per_zspage)) {
2245				pool->size_class[i] = prev_class;
2246				continue;
2247			}
2248		}
2249
2250		class = kzalloc(sizeof(struct size_class), GFP_KERNEL);
2251		if (!class)
2252			goto err;
2253
2254		class->size = size;
2255		class->index = i;
2256		class->pages_per_zspage = pages_per_zspage;
2257		class->objs_per_zspage = objs_per_zspage;
 
2258		pool->size_class[i] = class;
2259
2260		fullness = ZS_INUSE_RATIO_0;
2261		while (fullness < NR_FULLNESS_GROUPS) {
2262			INIT_LIST_HEAD(&class->fullness_list[fullness]);
2263			fullness++;
2264		}
2265
2266		prev_class = class;
2267	}
2268
2269	/* debug only, don't abort if it fails */
2270	zs_pool_stat_create(pool, name);
2271
 
 
 
2272	/*
2273	 * Not critical since shrinker is only used to trigger internal
2274	 * defragmentation of the pool which is pretty optional thing.  If
2275	 * registration fails we still can use the pool normally and user can
2276	 * trigger compaction manually. Thus, ignore return code.
2277	 */
2278	zs_register_shrinker(pool);
2279
2280	return pool;
2281
2282err:
2283	zs_destroy_pool(pool);
2284	return NULL;
2285}
2286EXPORT_SYMBOL_GPL(zs_create_pool);
2287
2288void zs_destroy_pool(struct zs_pool *pool)
2289{
2290	int i;
2291
2292	zs_unregister_shrinker(pool);
2293	zs_flush_migration(pool);
2294	zs_pool_stat_destroy(pool);
2295
2296	for (i = 0; i < ZS_SIZE_CLASSES; i++) {
2297		int fg;
2298		struct size_class *class = pool->size_class[i];
2299
2300		if (!class)
2301			continue;
2302
2303		if (class->index != i)
2304			continue;
2305
2306		for (fg = ZS_INUSE_RATIO_0; fg < NR_FULLNESS_GROUPS; fg++) {
2307			if (list_empty(&class->fullness_list[fg]))
2308				continue;
2309
2310			pr_err("Class-%d fullness group %d is not empty\n",
2311			       class->size, fg);
2312		}
2313		kfree(class);
2314	}
2315
2316	destroy_cache(pool);
2317	kfree(pool->name);
2318	kfree(pool);
2319}
2320EXPORT_SYMBOL_GPL(zs_destroy_pool);
2321
2322static int __init zs_init(void)
2323{
2324	int ret;
2325
 
 
 
 
2326	ret = cpuhp_setup_state(CPUHP_MM_ZS_PREPARE, "mm/zsmalloc:prepare",
2327				zs_cpu_prepare, zs_cpu_dead);
2328	if (ret)
2329		goto out;
2330
2331#ifdef CONFIG_ZPOOL
2332	zpool_register_driver(&zs_zpool_driver);
2333#endif
2334
2335	zs_stat_init();
2336
2337	return 0;
2338
 
 
2339out:
2340	return ret;
2341}
2342
2343static void __exit zs_exit(void)
2344{
2345#ifdef CONFIG_ZPOOL
2346	zpool_unregister_driver(&zs_zpool_driver);
2347#endif
 
2348	cpuhp_remove_state(CPUHP_MM_ZS_PREPARE);
2349
2350	zs_stat_exit();
2351}
2352
2353module_init(zs_init);
2354module_exit(zs_exit);
2355
2356MODULE_LICENSE("Dual BSD/GPL");
2357MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");