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: PG_zsmalloc, lower 16 bit locate the first object 24 * offset in a subpage of a zspage 25 * 26 * Usage of struct page flags: 27 * PG_private: identifies the first component page 28 * PG_owner_priv_1: identifies the huge component page 29 * 30 */ 31 32 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 33 34 /* 35 * lock ordering: 36 * page_lock 37 * pool->migrate_lock 38 * class->lock 39 * zspage->lock 40 */ 41 42 #include <linux/module.h> 43 #include <linux/kernel.h> 44 #include <linux/sched.h> 45 #include <linux/bitops.h> 46 #include <linux/errno.h> 47 #include <linux/highmem.h> 48 #include <linux/string.h> 49 #include <linux/slab.h> 50 #include <linux/pgtable.h> 51 #include <asm/tlbflush.h> 52 #include <linux/cpumask.h> 53 #include <linux/cpu.h> 54 #include <linux/vmalloc.h> 55 #include <linux/preempt.h> 56 #include <linux/spinlock.h> 57 #include <linux/sprintf.h> 58 #include <linux/shrinker.h> 59 #include <linux/types.h> 60 #include <linux/debugfs.h> 61 #include <linux/zsmalloc.h> 62 #include <linux/zpool.h> 63 #include <linux/migrate.h> 64 #include <linux/wait.h> 65 #include <linux/pagemap.h> 66 #include <linux/fs.h> 67 #include <linux/local_lock.h> 68 69 #define ZSPAGE_MAGIC 0x58 70 71 /* 72 * This must be power of 2 and greater than or equal to sizeof(link_free). 73 * These two conditions ensure that any 'struct link_free' itself doesn't 74 * span more than 1 page which avoids complex case of mapping 2 pages simply 75 * to restore link_free pointer values. 76 */ 77 #define ZS_ALIGN 8 78 79 #define ZS_HANDLE_SIZE (sizeof(unsigned long)) 80 81 /* 82 * Object location (<PFN>, <obj_idx>) is encoded as 83 * a single (unsigned long) handle value. 84 * 85 * Note that object index <obj_idx> starts from 0. 86 * 87 * This is made more complicated by various memory models and PAE. 88 */ 89 90 #ifndef MAX_POSSIBLE_PHYSMEM_BITS 91 #ifdef MAX_PHYSMEM_BITS 92 #define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS 93 #else 94 /* 95 * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just 96 * be PAGE_SHIFT 97 */ 98 #define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG 99 #endif 100 #endif 101 102 #define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT) 103 104 /* 105 * Head in allocated object should have OBJ_ALLOCATED_TAG 106 * to identify the object was allocated or not. 107 * It's okay to add the status bit in the least bit because 108 * header keeps handle which is 4byte-aligned address so we 109 * have room for two bit at least. 110 */ 111 #define OBJ_ALLOCATED_TAG 1 112 113 #define OBJ_TAG_BITS 1 114 #define OBJ_TAG_MASK OBJ_ALLOCATED_TAG 115 116 #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS) 117 #define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1) 118 119 #define HUGE_BITS 1 120 #define FULLNESS_BITS 4 121 #define CLASS_BITS 8 122 #define MAGIC_VAL_BITS 8 123 124 #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 */ 159 enum 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 }; 167 168 enum 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 }; 174 175 struct zs_size_stat { 176 unsigned long objs[NR_CLASS_STAT_TYPES]; 177 }; 178 179 #ifdef CONFIG_ZSMALLOC_STAT 180 static struct dentry *zs_stat_root; 181 #endif 182 183 static size_t huge_class_size; 184 185 struct size_class { 186 spinlock_t lock; 187 struct list_head fullness_list[NR_FULLNESS_GROUPS]; 188 /* 189 * Size of objects stored in this class. Must be multiple 190 * of ZS_ALIGN. 191 */ 192 int size; 193 int objs_per_zspage; 194 /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */ 195 int pages_per_zspage; 196 197 unsigned int index; 198 struct zs_size_stat stats; 199 }; 200 201 /* 202 * Placed within free objects to form a singly linked list. 203 * For every zspage, zspage->freeobj gives head of this list. 204 * 205 * This must be power of 2 and less than or equal to ZS_ALIGN 206 */ 207 struct link_free { 208 union { 209 /* 210 * Free object index; 211 * It's valid for non-allocated object 212 */ 213 unsigned long next; 214 /* 215 * Handle of allocated object. 216 */ 217 unsigned long handle; 218 }; 219 }; 220 221 struct zs_pool { 222 const char *name; 223 224 struct size_class *size_class[ZS_SIZE_CLASSES]; 225 struct kmem_cache *handle_cachep; 226 struct kmem_cache *zspage_cachep; 227 228 atomic_long_t pages_allocated; 229 230 struct zs_pool_stats stats; 231 232 /* Compact classes */ 233 struct shrinker *shrinker; 234 235 #ifdef CONFIG_ZSMALLOC_STAT 236 struct dentry *stat_dentry; 237 #endif 238 #ifdef CONFIG_COMPACTION 239 struct work_struct free_work; 240 #endif 241 /* protect page/zspage migration */ 242 rwlock_t migrate_lock; 243 atomic_t compaction_in_progress; 244 }; 245 246 struct zspage { 247 struct { 248 unsigned int huge:HUGE_BITS; 249 unsigned int fullness:FULLNESS_BITS; 250 unsigned int class:CLASS_BITS + 1; 251 unsigned int magic:MAGIC_VAL_BITS; 252 }; 253 unsigned int inuse; 254 unsigned int freeobj; 255 struct page *first_page; 256 struct list_head list; /* fullness list */ 257 struct zs_pool *pool; 258 rwlock_t lock; 259 }; 260 261 struct mapping_area { 262 local_lock_t lock; 263 char *vm_buf; /* copy buffer for objects that span pages */ 264 char *vm_addr; /* address of kmap_atomic()'ed pages */ 265 enum zs_mapmode vm_mm; /* mapping mode */ 266 }; 267 268 /* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */ 269 static void SetZsHugePage(struct zspage *zspage) 270 { 271 zspage->huge = 1; 272 } 273 274 static bool ZsHugePage(struct zspage *zspage) 275 { 276 return zspage->huge; 277 } 278 279 static void migrate_lock_init(struct zspage *zspage); 280 static void migrate_read_lock(struct zspage *zspage); 281 static void migrate_read_unlock(struct zspage *zspage); 282 static void migrate_write_lock(struct zspage *zspage); 283 static void migrate_write_unlock(struct zspage *zspage); 284 285 #ifdef CONFIG_COMPACTION 286 static void kick_deferred_free(struct zs_pool *pool); 287 static void init_deferred_free(struct zs_pool *pool); 288 static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage); 289 #else 290 static void kick_deferred_free(struct zs_pool *pool) {} 291 static void init_deferred_free(struct zs_pool *pool) {} 292 static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage) {} 293 #endif 294 295 static int create_cache(struct zs_pool *pool) 296 { 297 char *name; 298 299 name = kasprintf(GFP_KERNEL, "zs_handle-%s", pool->name); 300 if (!name) 301 return -ENOMEM; 302 pool->handle_cachep = kmem_cache_create(name, ZS_HANDLE_SIZE, 303 0, 0, NULL); 304 kfree(name); 305 if (!pool->handle_cachep) 306 return -EINVAL; 307 308 name = kasprintf(GFP_KERNEL, "zspage-%s", pool->name); 309 if (!name) 310 return -ENOMEM; 311 pool->zspage_cachep = kmem_cache_create(name, sizeof(struct zspage), 312 0, 0, NULL); 313 kfree(name); 314 if (!pool->zspage_cachep) { 315 kmem_cache_destroy(pool->handle_cachep); 316 pool->handle_cachep = NULL; 317 return -EINVAL; 318 } 319 320 return 0; 321 } 322 323 static void destroy_cache(struct zs_pool *pool) 324 { 325 kmem_cache_destroy(pool->handle_cachep); 326 kmem_cache_destroy(pool->zspage_cachep); 327 } 328 329 static unsigned long cache_alloc_handle(struct zs_pool *pool, gfp_t gfp) 330 { 331 return (unsigned long)kmem_cache_alloc(pool->handle_cachep, 332 gfp & ~(__GFP_HIGHMEM|__GFP_MOVABLE)); 333 } 334 335 static void cache_free_handle(struct zs_pool *pool, unsigned long handle) 336 { 337 kmem_cache_free(pool->handle_cachep, (void *)handle); 338 } 339 340 static struct zspage *cache_alloc_zspage(struct zs_pool *pool, gfp_t flags) 341 { 342 return kmem_cache_zalloc(pool->zspage_cachep, 343 flags & ~(__GFP_HIGHMEM|__GFP_MOVABLE)); 344 } 345 346 static void cache_free_zspage(struct zs_pool *pool, struct zspage *zspage) 347 { 348 kmem_cache_free(pool->zspage_cachep, zspage); 349 } 350 351 /* class->lock(which owns the handle) synchronizes races */ 352 static void record_obj(unsigned long handle, unsigned long obj) 353 { 354 *(unsigned long *)handle = obj; 355 } 356 357 /* zpool driver */ 358 359 #ifdef CONFIG_ZPOOL 360 361 static void *zs_zpool_create(const char *name, gfp_t gfp) 362 { 363 /* 364 * Ignore global gfp flags: zs_malloc() may be invoked from 365 * different contexts and its caller must provide a valid 366 * gfp mask. 367 */ 368 return zs_create_pool(name); 369 } 370 371 static void zs_zpool_destroy(void *pool) 372 { 373 zs_destroy_pool(pool); 374 } 375 376 static int zs_zpool_malloc(void *pool, size_t size, gfp_t gfp, 377 unsigned long *handle) 378 { 379 *handle = zs_malloc(pool, size, gfp); 380 381 if (IS_ERR_VALUE(*handle)) 382 return PTR_ERR((void *)*handle); 383 return 0; 384 } 385 static void zs_zpool_free(void *pool, unsigned long handle) 386 { 387 zs_free(pool, handle); 388 } 389 390 static void *zs_zpool_map(void *pool, unsigned long handle, 391 enum zpool_mapmode mm) 392 { 393 enum zs_mapmode zs_mm; 394 395 switch (mm) { 396 case ZPOOL_MM_RO: 397 zs_mm = ZS_MM_RO; 398 break; 399 case ZPOOL_MM_WO: 400 zs_mm = ZS_MM_WO; 401 break; 402 case ZPOOL_MM_RW: 403 default: 404 zs_mm = ZS_MM_RW; 405 break; 406 } 407 408 return zs_map_object(pool, handle, zs_mm); 409 } 410 static void zs_zpool_unmap(void *pool, unsigned long handle) 411 { 412 zs_unmap_object(pool, handle); 413 } 414 415 static u64 zs_zpool_total_pages(void *pool) 416 { 417 return zs_get_total_pages(pool); 418 } 419 420 static struct zpool_driver zs_zpool_driver = { 421 .type = "zsmalloc", 422 .owner = THIS_MODULE, 423 .create = zs_zpool_create, 424 .destroy = zs_zpool_destroy, 425 .malloc_support_movable = true, 426 .malloc = zs_zpool_malloc, 427 .free = zs_zpool_free, 428 .map = zs_zpool_map, 429 .unmap = zs_zpool_unmap, 430 .total_pages = zs_zpool_total_pages, 431 }; 432 433 MODULE_ALIAS("zpool-zsmalloc"); 434 #endif /* CONFIG_ZPOOL */ 435 436 /* per-cpu VM mapping areas for zspage accesses that cross page boundaries */ 437 static DEFINE_PER_CPU(struct mapping_area, zs_map_area) = { 438 .lock = INIT_LOCAL_LOCK(lock), 439 }; 440 441 static __maybe_unused int is_first_page(struct page *page) 442 { 443 return PagePrivate(page); 444 } 445 446 /* Protected by class->lock */ 447 static inline int get_zspage_inuse(struct zspage *zspage) 448 { 449 return zspage->inuse; 450 } 451 452 453 static inline void mod_zspage_inuse(struct zspage *zspage, int val) 454 { 455 zspage->inuse += val; 456 } 457 458 static inline struct page *get_first_page(struct zspage *zspage) 459 { 460 struct page *first_page = zspage->first_page; 461 462 VM_BUG_ON_PAGE(!is_first_page(first_page), first_page); 463 return first_page; 464 } 465 466 #define FIRST_OBJ_PAGE_TYPE_MASK 0xffff 467 468 static inline void reset_first_obj_offset(struct page *page) 469 { 470 VM_WARN_ON_ONCE(!PageZsmalloc(page)); 471 page->page_type |= FIRST_OBJ_PAGE_TYPE_MASK; 472 } 473 474 static inline unsigned int get_first_obj_offset(struct page *page) 475 { 476 VM_WARN_ON_ONCE(!PageZsmalloc(page)); 477 return page->page_type & FIRST_OBJ_PAGE_TYPE_MASK; 478 } 479 480 static inline void set_first_obj_offset(struct page *page, unsigned int offset) 481 { 482 /* With 16 bit available, we can support offsets into 64 KiB pages. */ 483 BUILD_BUG_ON(PAGE_SIZE > SZ_64K); 484 VM_WARN_ON_ONCE(!PageZsmalloc(page)); 485 VM_WARN_ON_ONCE(offset & ~FIRST_OBJ_PAGE_TYPE_MASK); 486 page->page_type &= ~FIRST_OBJ_PAGE_TYPE_MASK; 487 page->page_type |= offset & FIRST_OBJ_PAGE_TYPE_MASK; 488 } 489 490 static inline unsigned int get_freeobj(struct zspage *zspage) 491 { 492 return zspage->freeobj; 493 } 494 495 static inline void set_freeobj(struct zspage *zspage, unsigned int obj) 496 { 497 zspage->freeobj = obj; 498 } 499 500 static struct size_class *zspage_class(struct zs_pool *pool, 501 struct zspage *zspage) 502 { 503 return pool->size_class[zspage->class]; 504 } 505 506 /* 507 * zsmalloc divides the pool into various size classes where each 508 * class maintains a list of zspages where each zspage is divided 509 * into equal sized chunks. Each allocation falls into one of these 510 * classes depending on its size. This function returns index of the 511 * size class which has chunk size big enough to hold the given size. 512 */ 513 static int get_size_class_index(int size) 514 { 515 int idx = 0; 516 517 if (likely(size > ZS_MIN_ALLOC_SIZE)) 518 idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE, 519 ZS_SIZE_CLASS_DELTA); 520 521 return min_t(int, ZS_SIZE_CLASSES - 1, idx); 522 } 523 524 static inline void class_stat_add(struct size_class *class, int type, 525 unsigned long cnt) 526 { 527 class->stats.objs[type] += cnt; 528 } 529 530 static inline void class_stat_sub(struct size_class *class, int type, 531 unsigned long cnt) 532 { 533 class->stats.objs[type] -= cnt; 534 } 535 536 static inline unsigned long class_stat_read(struct size_class *class, int type) 537 { 538 return class->stats.objs[type]; 539 } 540 541 #ifdef CONFIG_ZSMALLOC_STAT 542 543 static void __init zs_stat_init(void) 544 { 545 if (!debugfs_initialized()) { 546 pr_warn("debugfs not available, stat dir not created\n"); 547 return; 548 } 549 550 zs_stat_root = debugfs_create_dir("zsmalloc", NULL); 551 } 552 553 static void __exit zs_stat_exit(void) 554 { 555 debugfs_remove_recursive(zs_stat_root); 556 } 557 558 static unsigned long zs_can_compact(struct size_class *class); 559 560 static int zs_stats_size_show(struct seq_file *s, void *v) 561 { 562 int i, fg; 563 struct zs_pool *pool = s->private; 564 struct size_class *class; 565 int objs_per_zspage; 566 unsigned long obj_allocated, obj_used, pages_used, freeable; 567 unsigned long total_objs = 0, total_used_objs = 0, total_pages = 0; 568 unsigned long total_freeable = 0; 569 unsigned long inuse_totals[NR_FULLNESS_GROUPS] = {0, }; 570 571 seq_printf(s, " %5s %5s %9s %9s %9s %9s %9s %9s %9s %9s %9s %9s %9s %13s %10s %10s %16s %8s\n", 572 "class", "size", "10%", "20%", "30%", "40%", 573 "50%", "60%", "70%", "80%", "90%", "99%", "100%", 574 "obj_allocated", "obj_used", "pages_used", 575 "pages_per_zspage", "freeable"); 576 577 for (i = 0; i < ZS_SIZE_CLASSES; i++) { 578 579 class = pool->size_class[i]; 580 581 if (class->index != i) 582 continue; 583 584 spin_lock(&class->lock); 585 586 seq_printf(s, " %5u %5u ", i, class->size); 587 for (fg = ZS_INUSE_RATIO_10; fg < NR_FULLNESS_GROUPS; fg++) { 588 inuse_totals[fg] += class_stat_read(class, fg); 589 seq_printf(s, "%9lu ", class_stat_read(class, fg)); 590 } 591 592 obj_allocated = class_stat_read(class, ZS_OBJS_ALLOCATED); 593 obj_used = class_stat_read(class, ZS_OBJS_INUSE); 594 freeable = zs_can_compact(class); 595 spin_unlock(&class->lock); 596 597 objs_per_zspage = class->objs_per_zspage; 598 pages_used = obj_allocated / objs_per_zspage * 599 class->pages_per_zspage; 600 601 seq_printf(s, "%13lu %10lu %10lu %16d %8lu\n", 602 obj_allocated, obj_used, pages_used, 603 class->pages_per_zspage, freeable); 604 605 total_objs += obj_allocated; 606 total_used_objs += obj_used; 607 total_pages += pages_used; 608 total_freeable += freeable; 609 } 610 611 seq_puts(s, "\n"); 612 seq_printf(s, " %5s %5s ", "Total", ""); 613 614 for (fg = ZS_INUSE_RATIO_10; fg < NR_FULLNESS_GROUPS; fg++) 615 seq_printf(s, "%9lu ", inuse_totals[fg]); 616 617 seq_printf(s, "%13lu %10lu %10lu %16s %8lu\n", 618 total_objs, total_used_objs, total_pages, "", 619 total_freeable); 620 621 return 0; 622 } 623 DEFINE_SHOW_ATTRIBUTE(zs_stats_size); 624 625 static void zs_pool_stat_create(struct zs_pool *pool, const char *name) 626 { 627 if (!zs_stat_root) { 628 pr_warn("no root stat dir, not creating <%s> stat dir\n", name); 629 return; 630 } 631 632 pool->stat_dentry = debugfs_create_dir(name, zs_stat_root); 633 634 debugfs_create_file("classes", S_IFREG | 0444, pool->stat_dentry, pool, 635 &zs_stats_size_fops); 636 } 637 638 static void zs_pool_stat_destroy(struct zs_pool *pool) 639 { 640 debugfs_remove_recursive(pool->stat_dentry); 641 } 642 643 #else /* CONFIG_ZSMALLOC_STAT */ 644 static void __init zs_stat_init(void) 645 { 646 } 647 648 static void __exit zs_stat_exit(void) 649 { 650 } 651 652 static inline void zs_pool_stat_create(struct zs_pool *pool, const char *name) 653 { 654 } 655 656 static inline void zs_pool_stat_destroy(struct zs_pool *pool) 657 { 658 } 659 #endif 660 661 662 /* 663 * For each size class, zspages are divided into different groups 664 * depending on their usage ratio. This function returns fullness 665 * status of the given page. 666 */ 667 static int get_fullness_group(struct size_class *class, struct zspage *zspage) 668 { 669 int inuse, objs_per_zspage, ratio; 670 671 inuse = get_zspage_inuse(zspage); 672 objs_per_zspage = class->objs_per_zspage; 673 674 if (inuse == 0) 675 return ZS_INUSE_RATIO_0; 676 if (inuse == objs_per_zspage) 677 return ZS_INUSE_RATIO_100; 678 679 ratio = 100 * inuse / objs_per_zspage; 680 /* 681 * Take integer division into consideration: a page with one inuse 682 * object out of 127 possible, will end up having 0 usage ratio, 683 * which is wrong as it belongs in ZS_INUSE_RATIO_10 fullness group. 684 */ 685 return ratio / 10 + 1; 686 } 687 688 /* 689 * Each size class maintains various freelists and zspages are assigned 690 * to one of these freelists based on the number of live objects they 691 * have. This functions inserts the given zspage into the freelist 692 * identified by <class, fullness_group>. 693 */ 694 static void insert_zspage(struct size_class *class, 695 struct zspage *zspage, 696 int fullness) 697 { 698 class_stat_add(class, fullness, 1); 699 list_add(&zspage->list, &class->fullness_list[fullness]); 700 zspage->fullness = fullness; 701 } 702 703 /* 704 * This function removes the given zspage from the freelist identified 705 * by <class, fullness_group>. 706 */ 707 static void remove_zspage(struct size_class *class, struct zspage *zspage) 708 { 709 int fullness = zspage->fullness; 710 711 VM_BUG_ON(list_empty(&class->fullness_list[fullness])); 712 713 list_del_init(&zspage->list); 714 class_stat_sub(class, fullness, 1); 715 } 716 717 /* 718 * Each size class maintains zspages in different fullness groups depending 719 * on the number of live objects they contain. When allocating or freeing 720 * objects, the fullness status of the page can change, for instance, from 721 * INUSE_RATIO_80 to INUSE_RATIO_70 when freeing an object. This function 722 * checks if such a status change has occurred for the given page and 723 * accordingly moves the page from the list of the old fullness group to that 724 * of the new fullness group. 725 */ 726 static int fix_fullness_group(struct size_class *class, struct zspage *zspage) 727 { 728 int newfg; 729 730 newfg = get_fullness_group(class, zspage); 731 if (newfg == zspage->fullness) 732 goto out; 733 734 remove_zspage(class, zspage); 735 insert_zspage(class, zspage, newfg); 736 out: 737 return newfg; 738 } 739 740 static struct zspage *get_zspage(struct page *page) 741 { 742 struct zspage *zspage = (struct zspage *)page_private(page); 743 744 BUG_ON(zspage->magic != ZSPAGE_MAGIC); 745 return zspage; 746 } 747 748 static struct page *get_next_page(struct page *page) 749 { 750 struct zspage *zspage = get_zspage(page); 751 752 if (unlikely(ZsHugePage(zspage))) 753 return NULL; 754 755 return (struct page *)page->index; 756 } 757 758 /** 759 * obj_to_location - get (<page>, <obj_idx>) from encoded object value 760 * @obj: the encoded object value 761 * @page: page object resides in zspage 762 * @obj_idx: object index 763 */ 764 static void obj_to_location(unsigned long obj, struct page **page, 765 unsigned int *obj_idx) 766 { 767 *page = pfn_to_page(obj >> OBJ_INDEX_BITS); 768 *obj_idx = (obj & OBJ_INDEX_MASK); 769 } 770 771 static void obj_to_page(unsigned long obj, struct page **page) 772 { 773 *page = pfn_to_page(obj >> OBJ_INDEX_BITS); 774 } 775 776 /** 777 * location_to_obj - get obj value encoded from (<page>, <obj_idx>) 778 * @page: page object resides in zspage 779 * @obj_idx: object index 780 */ 781 static unsigned long location_to_obj(struct page *page, unsigned int obj_idx) 782 { 783 unsigned long obj; 784 785 obj = page_to_pfn(page) << OBJ_INDEX_BITS; 786 obj |= obj_idx & OBJ_INDEX_MASK; 787 788 return obj; 789 } 790 791 static unsigned long handle_to_obj(unsigned long handle) 792 { 793 return *(unsigned long *)handle; 794 } 795 796 static inline bool obj_allocated(struct page *page, void *obj, 797 unsigned long *phandle) 798 { 799 unsigned long handle; 800 struct zspage *zspage = get_zspage(page); 801 802 if (unlikely(ZsHugePage(zspage))) { 803 VM_BUG_ON_PAGE(!is_first_page(page), page); 804 handle = page->index; 805 } else 806 handle = *(unsigned long *)obj; 807 808 if (!(handle & OBJ_ALLOCATED_TAG)) 809 return false; 810 811 /* Clear all tags before returning the handle */ 812 *phandle = handle & ~OBJ_TAG_MASK; 813 return true; 814 } 815 816 static void reset_page(struct page *page) 817 { 818 __ClearPageMovable(page); 819 ClearPagePrivate(page); 820 set_page_private(page, 0); 821 page->index = 0; 822 reset_first_obj_offset(page); 823 __ClearPageZsmalloc(page); 824 } 825 826 static int trylock_zspage(struct zspage *zspage) 827 { 828 struct page *cursor, *fail; 829 830 for (cursor = get_first_page(zspage); cursor != NULL; cursor = 831 get_next_page(cursor)) { 832 if (!trylock_page(cursor)) { 833 fail = cursor; 834 goto unlock; 835 } 836 } 837 838 return 1; 839 unlock: 840 for (cursor = get_first_page(zspage); cursor != fail; cursor = 841 get_next_page(cursor)) 842 unlock_page(cursor); 843 844 return 0; 845 } 846 847 static void __free_zspage(struct zs_pool *pool, struct size_class *class, 848 struct zspage *zspage) 849 { 850 struct page *page, *next; 851 852 assert_spin_locked(&class->lock); 853 854 VM_BUG_ON(get_zspage_inuse(zspage)); 855 VM_BUG_ON(zspage->fullness != ZS_INUSE_RATIO_0); 856 857 next = page = get_first_page(zspage); 858 do { 859 VM_BUG_ON_PAGE(!PageLocked(page), page); 860 next = get_next_page(page); 861 reset_page(page); 862 unlock_page(page); 863 dec_zone_page_state(page, NR_ZSPAGES); 864 put_page(page); 865 page = next; 866 } while (page != NULL); 867 868 cache_free_zspage(pool, zspage); 869 870 class_stat_sub(class, ZS_OBJS_ALLOCATED, class->objs_per_zspage); 871 atomic_long_sub(class->pages_per_zspage, &pool->pages_allocated); 872 } 873 874 static void free_zspage(struct zs_pool *pool, struct size_class *class, 875 struct zspage *zspage) 876 { 877 VM_BUG_ON(get_zspage_inuse(zspage)); 878 VM_BUG_ON(list_empty(&zspage->list)); 879 880 /* 881 * Since zs_free couldn't be sleepable, this function cannot call 882 * lock_page. The page locks trylock_zspage got will be released 883 * by __free_zspage. 884 */ 885 if (!trylock_zspage(zspage)) { 886 kick_deferred_free(pool); 887 return; 888 } 889 890 remove_zspage(class, zspage); 891 __free_zspage(pool, class, zspage); 892 } 893 894 /* Initialize a newly allocated zspage */ 895 static void init_zspage(struct size_class *class, struct zspage *zspage) 896 { 897 unsigned int freeobj = 1; 898 unsigned long off = 0; 899 struct page *page = get_first_page(zspage); 900 901 while (page) { 902 struct page *next_page; 903 struct link_free *link; 904 void *vaddr; 905 906 set_first_obj_offset(page, off); 907 908 vaddr = kmap_atomic(page); 909 link = (struct link_free *)vaddr + off / sizeof(*link); 910 911 while ((off += class->size) < PAGE_SIZE) { 912 link->next = freeobj++ << OBJ_TAG_BITS; 913 link += class->size / sizeof(*link); 914 } 915 916 /* 917 * We now come to the last (full or partial) object on this 918 * page, which must point to the first object on the next 919 * page (if present) 920 */ 921 next_page = get_next_page(page); 922 if (next_page) { 923 link->next = freeobj++ << OBJ_TAG_BITS; 924 } else { 925 /* 926 * Reset OBJ_TAG_BITS bit to last link to tell 927 * whether it's allocated object or not. 928 */ 929 link->next = -1UL << OBJ_TAG_BITS; 930 } 931 kunmap_atomic(vaddr); 932 page = next_page; 933 off %= PAGE_SIZE; 934 } 935 936 set_freeobj(zspage, 0); 937 } 938 939 static void create_page_chain(struct size_class *class, struct zspage *zspage, 940 struct page *pages[]) 941 { 942 int i; 943 struct page *page; 944 struct page *prev_page = NULL; 945 int nr_pages = class->pages_per_zspage; 946 947 /* 948 * Allocate individual pages and link them together as: 949 * 1. all pages are linked together using page->index 950 * 2. each sub-page point to zspage using page->private 951 * 952 * we set PG_private to identify the first page (i.e. no other sub-page 953 * has this flag set). 954 */ 955 for (i = 0; i < nr_pages; i++) { 956 page = pages[i]; 957 set_page_private(page, (unsigned long)zspage); 958 page->index = 0; 959 if (i == 0) { 960 zspage->first_page = page; 961 SetPagePrivate(page); 962 if (unlikely(class->objs_per_zspage == 1 && 963 class->pages_per_zspage == 1)) 964 SetZsHugePage(zspage); 965 } else { 966 prev_page->index = (unsigned long)page; 967 } 968 prev_page = page; 969 } 970 } 971 972 /* 973 * Allocate a zspage for the given size class 974 */ 975 static struct zspage *alloc_zspage(struct zs_pool *pool, 976 struct size_class *class, 977 gfp_t gfp) 978 { 979 int i; 980 struct page *pages[ZS_MAX_PAGES_PER_ZSPAGE]; 981 struct zspage *zspage = cache_alloc_zspage(pool, gfp); 982 983 if (!zspage) 984 return NULL; 985 986 zspage->magic = ZSPAGE_MAGIC; 987 migrate_lock_init(zspage); 988 989 for (i = 0; i < class->pages_per_zspage; i++) { 990 struct page *page; 991 992 page = alloc_page(gfp); 993 if (!page) { 994 while (--i >= 0) { 995 dec_zone_page_state(pages[i], NR_ZSPAGES); 996 __ClearPageZsmalloc(pages[i]); 997 __free_page(pages[i]); 998 } 999 cache_free_zspage(pool, zspage); 1000 return NULL; 1001 } 1002 __SetPageZsmalloc(page); 1003 1004 inc_zone_page_state(page, NR_ZSPAGES); 1005 pages[i] = page; 1006 } 1007 1008 create_page_chain(class, zspage, pages); 1009 init_zspage(class, zspage); 1010 zspage->pool = pool; 1011 zspage->class = class->index; 1012 1013 return zspage; 1014 } 1015 1016 static struct zspage *find_get_zspage(struct size_class *class) 1017 { 1018 int i; 1019 struct zspage *zspage; 1020 1021 for (i = ZS_INUSE_RATIO_99; i >= ZS_INUSE_RATIO_0; i--) { 1022 zspage = list_first_entry_or_null(&class->fullness_list[i], 1023 struct zspage, list); 1024 if (zspage) 1025 break; 1026 } 1027 1028 return zspage; 1029 } 1030 1031 static inline int __zs_cpu_up(struct mapping_area *area) 1032 { 1033 /* 1034 * Make sure we don't leak memory if a cpu UP notification 1035 * and zs_init() race and both call zs_cpu_up() on the same cpu 1036 */ 1037 if (area->vm_buf) 1038 return 0; 1039 area->vm_buf = kmalloc(ZS_MAX_ALLOC_SIZE, GFP_KERNEL); 1040 if (!area->vm_buf) 1041 return -ENOMEM; 1042 return 0; 1043 } 1044 1045 static inline void __zs_cpu_down(struct mapping_area *area) 1046 { 1047 kfree(area->vm_buf); 1048 area->vm_buf = NULL; 1049 } 1050 1051 static void *__zs_map_object(struct mapping_area *area, 1052 struct page *pages[2], int off, int size) 1053 { 1054 int sizes[2]; 1055 void *addr; 1056 char *buf = area->vm_buf; 1057 1058 /* disable page faults to match kmap_atomic() return conditions */ 1059 pagefault_disable(); 1060 1061 /* no read fastpath */ 1062 if (area->vm_mm == ZS_MM_WO) 1063 goto out; 1064 1065 sizes[0] = PAGE_SIZE - off; 1066 sizes[1] = size - sizes[0]; 1067 1068 /* copy object to per-cpu buffer */ 1069 addr = kmap_atomic(pages[0]); 1070 memcpy(buf, addr + off, sizes[0]); 1071 kunmap_atomic(addr); 1072 addr = kmap_atomic(pages[1]); 1073 memcpy(buf + sizes[0], addr, sizes[1]); 1074 kunmap_atomic(addr); 1075 out: 1076 return area->vm_buf; 1077 } 1078 1079 static void __zs_unmap_object(struct mapping_area *area, 1080 struct page *pages[2], int off, int size) 1081 { 1082 int sizes[2]; 1083 void *addr; 1084 char *buf; 1085 1086 /* no write fastpath */ 1087 if (area->vm_mm == ZS_MM_RO) 1088 goto out; 1089 1090 buf = area->vm_buf; 1091 buf = buf + ZS_HANDLE_SIZE; 1092 size -= ZS_HANDLE_SIZE; 1093 off += ZS_HANDLE_SIZE; 1094 1095 sizes[0] = PAGE_SIZE - off; 1096 sizes[1] = size - sizes[0]; 1097 1098 /* copy per-cpu buffer to object */ 1099 addr = kmap_atomic(pages[0]); 1100 memcpy(addr + off, buf, sizes[0]); 1101 kunmap_atomic(addr); 1102 addr = kmap_atomic(pages[1]); 1103 memcpy(addr, buf + sizes[0], sizes[1]); 1104 kunmap_atomic(addr); 1105 1106 out: 1107 /* enable page faults to match kunmap_atomic() return conditions */ 1108 pagefault_enable(); 1109 } 1110 1111 static int zs_cpu_prepare(unsigned int cpu) 1112 { 1113 struct mapping_area *area; 1114 1115 area = &per_cpu(zs_map_area, cpu); 1116 return __zs_cpu_up(area); 1117 } 1118 1119 static int zs_cpu_dead(unsigned int cpu) 1120 { 1121 struct mapping_area *area; 1122 1123 area = &per_cpu(zs_map_area, cpu); 1124 __zs_cpu_down(area); 1125 return 0; 1126 } 1127 1128 static bool can_merge(struct size_class *prev, int pages_per_zspage, 1129 int objs_per_zspage) 1130 { 1131 if (prev->pages_per_zspage == pages_per_zspage && 1132 prev->objs_per_zspage == objs_per_zspage) 1133 return true; 1134 1135 return false; 1136 } 1137 1138 static bool zspage_full(struct size_class *class, struct zspage *zspage) 1139 { 1140 return get_zspage_inuse(zspage) == class->objs_per_zspage; 1141 } 1142 1143 static bool zspage_empty(struct zspage *zspage) 1144 { 1145 return get_zspage_inuse(zspage) == 0; 1146 } 1147 1148 /** 1149 * zs_lookup_class_index() - Returns index of the zsmalloc &size_class 1150 * that hold objects of the provided size. 1151 * @pool: zsmalloc pool to use 1152 * @size: object size 1153 * 1154 * Context: Any context. 1155 * 1156 * Return: the index of the zsmalloc &size_class that hold objects of the 1157 * provided size. 1158 */ 1159 unsigned int zs_lookup_class_index(struct zs_pool *pool, unsigned int size) 1160 { 1161 struct size_class *class; 1162 1163 class = pool->size_class[get_size_class_index(size)]; 1164 1165 return class->index; 1166 } 1167 EXPORT_SYMBOL_GPL(zs_lookup_class_index); 1168 1169 unsigned long zs_get_total_pages(struct zs_pool *pool) 1170 { 1171 return atomic_long_read(&pool->pages_allocated); 1172 } 1173 EXPORT_SYMBOL_GPL(zs_get_total_pages); 1174 1175 /** 1176 * zs_map_object - get address of allocated object from handle. 1177 * @pool: pool from which the object was allocated 1178 * @handle: handle returned from zs_malloc 1179 * @mm: mapping mode to use 1180 * 1181 * Before using an object allocated from zs_malloc, it must be mapped using 1182 * this function. When done with the object, it must be unmapped using 1183 * zs_unmap_object. 1184 * 1185 * Only one object can be mapped per cpu at a time. There is no protection 1186 * against nested mappings. 1187 * 1188 * This function returns with preemption and page faults disabled. 1189 */ 1190 void *zs_map_object(struct zs_pool *pool, unsigned long handle, 1191 enum zs_mapmode mm) 1192 { 1193 struct zspage *zspage; 1194 struct page *page; 1195 unsigned long obj, off; 1196 unsigned int obj_idx; 1197 1198 struct size_class *class; 1199 struct mapping_area *area; 1200 struct page *pages[2]; 1201 void *ret; 1202 1203 /* 1204 * Because we use per-cpu mapping areas shared among the 1205 * pools/users, we can't allow mapping in interrupt context 1206 * because it can corrupt another users mappings. 1207 */ 1208 BUG_ON(in_interrupt()); 1209 1210 /* It guarantees it can get zspage from handle safely */ 1211 read_lock(&pool->migrate_lock); 1212 obj = handle_to_obj(handle); 1213 obj_to_location(obj, &page, &obj_idx); 1214 zspage = get_zspage(page); 1215 1216 /* 1217 * migration cannot move any zpages in this zspage. Here, class->lock 1218 * is too heavy since callers would take some time until they calls 1219 * zs_unmap_object API so delegate the locking from class to zspage 1220 * which is smaller granularity. 1221 */ 1222 migrate_read_lock(zspage); 1223 read_unlock(&pool->migrate_lock); 1224 1225 class = zspage_class(pool, zspage); 1226 off = offset_in_page(class->size * obj_idx); 1227 1228 local_lock(&zs_map_area.lock); 1229 area = this_cpu_ptr(&zs_map_area); 1230 area->vm_mm = mm; 1231 if (off + class->size <= PAGE_SIZE) { 1232 /* this object is contained entirely within a page */ 1233 area->vm_addr = kmap_atomic(page); 1234 ret = area->vm_addr + off; 1235 goto out; 1236 } 1237 1238 /* this object spans two pages */ 1239 pages[0] = page; 1240 pages[1] = get_next_page(page); 1241 BUG_ON(!pages[1]); 1242 1243 ret = __zs_map_object(area, pages, off, class->size); 1244 out: 1245 if (likely(!ZsHugePage(zspage))) 1246 ret += ZS_HANDLE_SIZE; 1247 1248 return ret; 1249 } 1250 EXPORT_SYMBOL_GPL(zs_map_object); 1251 1252 void zs_unmap_object(struct zs_pool *pool, unsigned long handle) 1253 { 1254 struct zspage *zspage; 1255 struct page *page; 1256 unsigned long obj, off; 1257 unsigned int obj_idx; 1258 1259 struct size_class *class; 1260 struct mapping_area *area; 1261 1262 obj = handle_to_obj(handle); 1263 obj_to_location(obj, &page, &obj_idx); 1264 zspage = get_zspage(page); 1265 class = zspage_class(pool, zspage); 1266 off = offset_in_page(class->size * obj_idx); 1267 1268 area = this_cpu_ptr(&zs_map_area); 1269 if (off + class->size <= PAGE_SIZE) 1270 kunmap_atomic(area->vm_addr); 1271 else { 1272 struct page *pages[2]; 1273 1274 pages[0] = page; 1275 pages[1] = get_next_page(page); 1276 BUG_ON(!pages[1]); 1277 1278 __zs_unmap_object(area, pages, off, class->size); 1279 } 1280 local_unlock(&zs_map_area.lock); 1281 1282 migrate_read_unlock(zspage); 1283 } 1284 EXPORT_SYMBOL_GPL(zs_unmap_object); 1285 1286 /** 1287 * zs_huge_class_size() - Returns the size (in bytes) of the first huge 1288 * zsmalloc &size_class. 1289 * @pool: zsmalloc pool to use 1290 * 1291 * The function returns the size of the first huge class - any object of equal 1292 * or bigger size will be stored in zspage consisting of a single physical 1293 * page. 1294 * 1295 * Context: Any context. 1296 * 1297 * Return: the size (in bytes) of the first huge zsmalloc &size_class. 1298 */ 1299 size_t zs_huge_class_size(struct zs_pool *pool) 1300 { 1301 return huge_class_size; 1302 } 1303 EXPORT_SYMBOL_GPL(zs_huge_class_size); 1304 1305 static unsigned long obj_malloc(struct zs_pool *pool, 1306 struct zspage *zspage, unsigned long handle) 1307 { 1308 int i, nr_page, offset; 1309 unsigned long obj; 1310 struct link_free *link; 1311 struct size_class *class; 1312 1313 struct page *m_page; 1314 unsigned long m_offset; 1315 void *vaddr; 1316 1317 class = pool->size_class[zspage->class]; 1318 obj = get_freeobj(zspage); 1319 1320 offset = obj * class->size; 1321 nr_page = offset >> PAGE_SHIFT; 1322 m_offset = offset_in_page(offset); 1323 m_page = get_first_page(zspage); 1324 1325 for (i = 0; i < nr_page; i++) 1326 m_page = get_next_page(m_page); 1327 1328 vaddr = kmap_atomic(m_page); 1329 link = (struct link_free *)vaddr + m_offset / sizeof(*link); 1330 set_freeobj(zspage, link->next >> OBJ_TAG_BITS); 1331 if (likely(!ZsHugePage(zspage))) 1332 /* record handle in the header of allocated chunk */ 1333 link->handle = handle | OBJ_ALLOCATED_TAG; 1334 else 1335 /* record handle to page->index */ 1336 zspage->first_page->index = handle | OBJ_ALLOCATED_TAG; 1337 1338 kunmap_atomic(vaddr); 1339 mod_zspage_inuse(zspage, 1); 1340 1341 obj = location_to_obj(m_page, obj); 1342 record_obj(handle, obj); 1343 1344 return obj; 1345 } 1346 1347 1348 /** 1349 * zs_malloc - Allocate block of given size from pool. 1350 * @pool: pool to allocate from 1351 * @size: size of block to allocate 1352 * @gfp: gfp flags when allocating object 1353 * 1354 * On success, handle to the allocated object is returned, 1355 * otherwise an ERR_PTR(). 1356 * Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail. 1357 */ 1358 unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp) 1359 { 1360 unsigned long handle; 1361 struct size_class *class; 1362 int newfg; 1363 struct zspage *zspage; 1364 1365 if (unlikely(!size)) 1366 return (unsigned long)ERR_PTR(-EINVAL); 1367 1368 if (unlikely(size > ZS_MAX_ALLOC_SIZE)) 1369 return (unsigned long)ERR_PTR(-ENOSPC); 1370 1371 handle = cache_alloc_handle(pool, gfp); 1372 if (!handle) 1373 return (unsigned long)ERR_PTR(-ENOMEM); 1374 1375 /* extra space in chunk to keep the handle */ 1376 size += ZS_HANDLE_SIZE; 1377 class = pool->size_class[get_size_class_index(size)]; 1378 1379 /* class->lock effectively protects the zpage migration */ 1380 spin_lock(&class->lock); 1381 zspage = find_get_zspage(class); 1382 if (likely(zspage)) { 1383 obj_malloc(pool, zspage, handle); 1384 /* Now move the zspage to another fullness group, if required */ 1385 fix_fullness_group(class, zspage); 1386 class_stat_add(class, ZS_OBJS_INUSE, 1); 1387 1388 goto out; 1389 } 1390 1391 spin_unlock(&class->lock); 1392 1393 zspage = alloc_zspage(pool, class, gfp); 1394 if (!zspage) { 1395 cache_free_handle(pool, handle); 1396 return (unsigned long)ERR_PTR(-ENOMEM); 1397 } 1398 1399 spin_lock(&class->lock); 1400 obj_malloc(pool, zspage, handle); 1401 newfg = get_fullness_group(class, zspage); 1402 insert_zspage(class, zspage, newfg); 1403 atomic_long_add(class->pages_per_zspage, &pool->pages_allocated); 1404 class_stat_add(class, ZS_OBJS_ALLOCATED, class->objs_per_zspage); 1405 class_stat_add(class, ZS_OBJS_INUSE, 1); 1406 1407 /* We completely set up zspage so mark them as movable */ 1408 SetZsPageMovable(pool, zspage); 1409 out: 1410 spin_unlock(&class->lock); 1411 1412 return handle; 1413 } 1414 EXPORT_SYMBOL_GPL(zs_malloc); 1415 1416 static void obj_free(int class_size, unsigned long obj) 1417 { 1418 struct link_free *link; 1419 struct zspage *zspage; 1420 struct page *f_page; 1421 unsigned long f_offset; 1422 unsigned int f_objidx; 1423 void *vaddr; 1424 1425 obj_to_location(obj, &f_page, &f_objidx); 1426 f_offset = offset_in_page(class_size * f_objidx); 1427 zspage = get_zspage(f_page); 1428 1429 vaddr = kmap_atomic(f_page); 1430 link = (struct link_free *)(vaddr + f_offset); 1431 1432 /* Insert this object in containing zspage's freelist */ 1433 if (likely(!ZsHugePage(zspage))) 1434 link->next = get_freeobj(zspage) << OBJ_TAG_BITS; 1435 else 1436 f_page->index = 0; 1437 set_freeobj(zspage, f_objidx); 1438 1439 kunmap_atomic(vaddr); 1440 mod_zspage_inuse(zspage, -1); 1441 } 1442 1443 void zs_free(struct zs_pool *pool, unsigned long handle) 1444 { 1445 struct zspage *zspage; 1446 struct page *f_page; 1447 unsigned long obj; 1448 struct size_class *class; 1449 int fullness; 1450 1451 if (IS_ERR_OR_NULL((void *)handle)) 1452 return; 1453 1454 /* 1455 * The pool->migrate_lock protects the race with zpage's migration 1456 * so it's safe to get the page from handle. 1457 */ 1458 read_lock(&pool->migrate_lock); 1459 obj = handle_to_obj(handle); 1460 obj_to_page(obj, &f_page); 1461 zspage = get_zspage(f_page); 1462 class = zspage_class(pool, zspage); 1463 spin_lock(&class->lock); 1464 read_unlock(&pool->migrate_lock); 1465 1466 class_stat_sub(class, ZS_OBJS_INUSE, 1); 1467 obj_free(class->size, obj); 1468 1469 fullness = fix_fullness_group(class, zspage); 1470 if (fullness == ZS_INUSE_RATIO_0) 1471 free_zspage(pool, class, zspage); 1472 1473 spin_unlock(&class->lock); 1474 cache_free_handle(pool, handle); 1475 } 1476 EXPORT_SYMBOL_GPL(zs_free); 1477 1478 static void zs_object_copy(struct size_class *class, unsigned long dst, 1479 unsigned long src) 1480 { 1481 struct page *s_page, *d_page; 1482 unsigned int s_objidx, d_objidx; 1483 unsigned long s_off, d_off; 1484 void *s_addr, *d_addr; 1485 int s_size, d_size, size; 1486 int written = 0; 1487 1488 s_size = d_size = class->size; 1489 1490 obj_to_location(src, &s_page, &s_objidx); 1491 obj_to_location(dst, &d_page, &d_objidx); 1492 1493 s_off = offset_in_page(class->size * s_objidx); 1494 d_off = offset_in_page(class->size * d_objidx); 1495 1496 if (s_off + class->size > PAGE_SIZE) 1497 s_size = PAGE_SIZE - s_off; 1498 1499 if (d_off + class->size > PAGE_SIZE) 1500 d_size = PAGE_SIZE - d_off; 1501 1502 s_addr = kmap_atomic(s_page); 1503 d_addr = kmap_atomic(d_page); 1504 1505 while (1) { 1506 size = min(s_size, d_size); 1507 memcpy(d_addr + d_off, s_addr + s_off, size); 1508 written += size; 1509 1510 if (written == class->size) 1511 break; 1512 1513 s_off += size; 1514 s_size -= size; 1515 d_off += size; 1516 d_size -= size; 1517 1518 /* 1519 * Calling kunmap_atomic(d_addr) is necessary. kunmap_atomic() 1520 * calls must occurs in reverse order of calls to kmap_atomic(). 1521 * So, to call kunmap_atomic(s_addr) we should first call 1522 * kunmap_atomic(d_addr). For more details see 1523 * Documentation/mm/highmem.rst. 1524 */ 1525 if (s_off >= PAGE_SIZE) { 1526 kunmap_atomic(d_addr); 1527 kunmap_atomic(s_addr); 1528 s_page = get_next_page(s_page); 1529 s_addr = kmap_atomic(s_page); 1530 d_addr = kmap_atomic(d_page); 1531 s_size = class->size - written; 1532 s_off = 0; 1533 } 1534 1535 if (d_off >= PAGE_SIZE) { 1536 kunmap_atomic(d_addr); 1537 d_page = get_next_page(d_page); 1538 d_addr = kmap_atomic(d_page); 1539 d_size = class->size - written; 1540 d_off = 0; 1541 } 1542 } 1543 1544 kunmap_atomic(d_addr); 1545 kunmap_atomic(s_addr); 1546 } 1547 1548 /* 1549 * Find alloced object in zspage from index object and 1550 * return handle. 1551 */ 1552 static unsigned long find_alloced_obj(struct size_class *class, 1553 struct page *page, int *obj_idx) 1554 { 1555 unsigned int offset; 1556 int index = *obj_idx; 1557 unsigned long handle = 0; 1558 void *addr = kmap_atomic(page); 1559 1560 offset = get_first_obj_offset(page); 1561 offset += class->size * index; 1562 1563 while (offset < PAGE_SIZE) { 1564 if (obj_allocated(page, addr + offset, &handle)) 1565 break; 1566 1567 offset += class->size; 1568 index++; 1569 } 1570 1571 kunmap_atomic(addr); 1572 1573 *obj_idx = index; 1574 1575 return handle; 1576 } 1577 1578 static void migrate_zspage(struct zs_pool *pool, struct zspage *src_zspage, 1579 struct zspage *dst_zspage) 1580 { 1581 unsigned long used_obj, free_obj; 1582 unsigned long handle; 1583 int obj_idx = 0; 1584 struct page *s_page = get_first_page(src_zspage); 1585 struct size_class *class = pool->size_class[src_zspage->class]; 1586 1587 while (1) { 1588 handle = find_alloced_obj(class, s_page, &obj_idx); 1589 if (!handle) { 1590 s_page = get_next_page(s_page); 1591 if (!s_page) 1592 break; 1593 obj_idx = 0; 1594 continue; 1595 } 1596 1597 used_obj = handle_to_obj(handle); 1598 free_obj = obj_malloc(pool, dst_zspage, handle); 1599 zs_object_copy(class, free_obj, used_obj); 1600 obj_idx++; 1601 obj_free(class->size, used_obj); 1602 1603 /* Stop if there is no more space */ 1604 if (zspage_full(class, dst_zspage)) 1605 break; 1606 1607 /* Stop if there are no more objects to migrate */ 1608 if (zspage_empty(src_zspage)) 1609 break; 1610 } 1611 } 1612 1613 static struct zspage *isolate_src_zspage(struct size_class *class) 1614 { 1615 struct zspage *zspage; 1616 int fg; 1617 1618 for (fg = ZS_INUSE_RATIO_10; fg <= ZS_INUSE_RATIO_99; fg++) { 1619 zspage = list_first_entry_or_null(&class->fullness_list[fg], 1620 struct zspage, list); 1621 if (zspage) { 1622 remove_zspage(class, zspage); 1623 return zspage; 1624 } 1625 } 1626 1627 return zspage; 1628 } 1629 1630 static struct zspage *isolate_dst_zspage(struct size_class *class) 1631 { 1632 struct zspage *zspage; 1633 int fg; 1634 1635 for (fg = ZS_INUSE_RATIO_99; fg >= ZS_INUSE_RATIO_10; fg--) { 1636 zspage = list_first_entry_or_null(&class->fullness_list[fg], 1637 struct zspage, list); 1638 if (zspage) { 1639 remove_zspage(class, zspage); 1640 return zspage; 1641 } 1642 } 1643 1644 return zspage; 1645 } 1646 1647 /* 1648 * putback_zspage - add @zspage into right class's fullness list 1649 * @class: destination class 1650 * @zspage: target page 1651 * 1652 * Return @zspage's fullness status 1653 */ 1654 static int putback_zspage(struct size_class *class, struct zspage *zspage) 1655 { 1656 int fullness; 1657 1658 fullness = get_fullness_group(class, zspage); 1659 insert_zspage(class, zspage, fullness); 1660 1661 return fullness; 1662 } 1663 1664 #ifdef CONFIG_COMPACTION 1665 /* 1666 * To prevent zspage destroy during migration, zspage freeing should 1667 * hold locks of all pages in the zspage. 1668 */ 1669 static void lock_zspage(struct zspage *zspage) 1670 { 1671 struct page *curr_page, *page; 1672 1673 /* 1674 * Pages we haven't locked yet can be migrated off the list while we're 1675 * trying to lock them, so we need to be careful and only attempt to 1676 * lock each page under migrate_read_lock(). Otherwise, the page we lock 1677 * may no longer belong to the zspage. This means that we may wait for 1678 * the wrong page to unlock, so we must take a reference to the page 1679 * prior to waiting for it to unlock outside migrate_read_lock(). 1680 */ 1681 while (1) { 1682 migrate_read_lock(zspage); 1683 page = get_first_page(zspage); 1684 if (trylock_page(page)) 1685 break; 1686 get_page(page); 1687 migrate_read_unlock(zspage); 1688 wait_on_page_locked(page); 1689 put_page(page); 1690 } 1691 1692 curr_page = page; 1693 while ((page = get_next_page(curr_page))) { 1694 if (trylock_page(page)) { 1695 curr_page = page; 1696 } else { 1697 get_page(page); 1698 migrate_read_unlock(zspage); 1699 wait_on_page_locked(page); 1700 put_page(page); 1701 migrate_read_lock(zspage); 1702 } 1703 } 1704 migrate_read_unlock(zspage); 1705 } 1706 #endif /* CONFIG_COMPACTION */ 1707 1708 static void migrate_lock_init(struct zspage *zspage) 1709 { 1710 rwlock_init(&zspage->lock); 1711 } 1712 1713 static void migrate_read_lock(struct zspage *zspage) __acquires(&zspage->lock) 1714 { 1715 read_lock(&zspage->lock); 1716 } 1717 1718 static void migrate_read_unlock(struct zspage *zspage) __releases(&zspage->lock) 1719 { 1720 read_unlock(&zspage->lock); 1721 } 1722 1723 static void migrate_write_lock(struct zspage *zspage) 1724 { 1725 write_lock(&zspage->lock); 1726 } 1727 1728 static void migrate_write_unlock(struct zspage *zspage) 1729 { 1730 write_unlock(&zspage->lock); 1731 } 1732 1733 #ifdef CONFIG_COMPACTION 1734 1735 static const struct movable_operations zsmalloc_mops; 1736 1737 static void replace_sub_page(struct size_class *class, struct zspage *zspage, 1738 struct page *newpage, struct page *oldpage) 1739 { 1740 struct page *page; 1741 struct page *pages[ZS_MAX_PAGES_PER_ZSPAGE] = {NULL, }; 1742 int idx = 0; 1743 1744 page = get_first_page(zspage); 1745 do { 1746 if (page == oldpage) 1747 pages[idx] = newpage; 1748 else 1749 pages[idx] = page; 1750 idx++; 1751 } while ((page = get_next_page(page)) != NULL); 1752 1753 create_page_chain(class, zspage, pages); 1754 set_first_obj_offset(newpage, get_first_obj_offset(oldpage)); 1755 if (unlikely(ZsHugePage(zspage))) 1756 newpage->index = oldpage->index; 1757 __SetPageMovable(newpage, &zsmalloc_mops); 1758 } 1759 1760 static bool zs_page_isolate(struct page *page, isolate_mode_t mode) 1761 { 1762 /* 1763 * Page is locked so zspage couldn't be destroyed. For detail, look at 1764 * lock_zspage in free_zspage. 1765 */ 1766 VM_BUG_ON_PAGE(PageIsolated(page), page); 1767 1768 return true; 1769 } 1770 1771 static int zs_page_migrate(struct page *newpage, struct page *page, 1772 enum migrate_mode mode) 1773 { 1774 struct zs_pool *pool; 1775 struct size_class *class; 1776 struct zspage *zspage; 1777 struct page *dummy; 1778 void *s_addr, *d_addr, *addr; 1779 unsigned int offset; 1780 unsigned long handle; 1781 unsigned long old_obj, new_obj; 1782 unsigned int obj_idx; 1783 1784 VM_BUG_ON_PAGE(!PageIsolated(page), page); 1785 1786 /* We're committed, tell the world that this is a Zsmalloc page. */ 1787 __SetPageZsmalloc(newpage); 1788 1789 /* The page is locked, so this pointer must remain valid */ 1790 zspage = get_zspage(page); 1791 pool = zspage->pool; 1792 1793 /* 1794 * The pool migrate_lock protects the race between zpage migration 1795 * and zs_free. 1796 */ 1797 write_lock(&pool->migrate_lock); 1798 class = zspage_class(pool, zspage); 1799 1800 /* 1801 * the class lock protects zpage alloc/free in the zspage. 1802 */ 1803 spin_lock(&class->lock); 1804 /* the migrate_write_lock protects zpage access via zs_map_object */ 1805 migrate_write_lock(zspage); 1806 1807 offset = get_first_obj_offset(page); 1808 s_addr = kmap_atomic(page); 1809 1810 /* 1811 * Here, any user cannot access all objects in the zspage so let's move. 1812 */ 1813 d_addr = kmap_atomic(newpage); 1814 copy_page(d_addr, s_addr); 1815 kunmap_atomic(d_addr); 1816 1817 for (addr = s_addr + offset; addr < s_addr + PAGE_SIZE; 1818 addr += class->size) { 1819 if (obj_allocated(page, addr, &handle)) { 1820 1821 old_obj = handle_to_obj(handle); 1822 obj_to_location(old_obj, &dummy, &obj_idx); 1823 new_obj = (unsigned long)location_to_obj(newpage, 1824 obj_idx); 1825 record_obj(handle, new_obj); 1826 } 1827 } 1828 kunmap_atomic(s_addr); 1829 1830 replace_sub_page(class, zspage, newpage, page); 1831 /* 1832 * Since we complete the data copy and set up new zspage structure, 1833 * it's okay to release migration_lock. 1834 */ 1835 write_unlock(&pool->migrate_lock); 1836 spin_unlock(&class->lock); 1837 migrate_write_unlock(zspage); 1838 1839 get_page(newpage); 1840 if (page_zone(newpage) != page_zone(page)) { 1841 dec_zone_page_state(page, NR_ZSPAGES); 1842 inc_zone_page_state(newpage, NR_ZSPAGES); 1843 } 1844 1845 reset_page(page); 1846 put_page(page); 1847 1848 return MIGRATEPAGE_SUCCESS; 1849 } 1850 1851 static void zs_page_putback(struct page *page) 1852 { 1853 VM_BUG_ON_PAGE(!PageIsolated(page), page); 1854 } 1855 1856 static const struct movable_operations zsmalloc_mops = { 1857 .isolate_page = zs_page_isolate, 1858 .migrate_page = zs_page_migrate, 1859 .putback_page = zs_page_putback, 1860 }; 1861 1862 /* 1863 * Caller should hold page_lock of all pages in the zspage 1864 * In here, we cannot use zspage meta data. 1865 */ 1866 static void async_free_zspage(struct work_struct *work) 1867 { 1868 int i; 1869 struct size_class *class; 1870 struct zspage *zspage, *tmp; 1871 LIST_HEAD(free_pages); 1872 struct zs_pool *pool = container_of(work, struct zs_pool, 1873 free_work); 1874 1875 for (i = 0; i < ZS_SIZE_CLASSES; i++) { 1876 class = pool->size_class[i]; 1877 if (class->index != i) 1878 continue; 1879 1880 spin_lock(&class->lock); 1881 list_splice_init(&class->fullness_list[ZS_INUSE_RATIO_0], 1882 &free_pages); 1883 spin_unlock(&class->lock); 1884 } 1885 1886 list_for_each_entry_safe(zspage, tmp, &free_pages, list) { 1887 list_del(&zspage->list); 1888 lock_zspage(zspage); 1889 1890 class = zspage_class(pool, zspage); 1891 spin_lock(&class->lock); 1892 class_stat_sub(class, ZS_INUSE_RATIO_0, 1); 1893 __free_zspage(pool, class, zspage); 1894 spin_unlock(&class->lock); 1895 } 1896 }; 1897 1898 static void kick_deferred_free(struct zs_pool *pool) 1899 { 1900 schedule_work(&pool->free_work); 1901 } 1902 1903 static void zs_flush_migration(struct zs_pool *pool) 1904 { 1905 flush_work(&pool->free_work); 1906 } 1907 1908 static void init_deferred_free(struct zs_pool *pool) 1909 { 1910 INIT_WORK(&pool->free_work, async_free_zspage); 1911 } 1912 1913 static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage) 1914 { 1915 struct page *page = get_first_page(zspage); 1916 1917 do { 1918 WARN_ON(!trylock_page(page)); 1919 __SetPageMovable(page, &zsmalloc_mops); 1920 unlock_page(page); 1921 } while ((page = get_next_page(page)) != NULL); 1922 } 1923 #else 1924 static inline void zs_flush_migration(struct zs_pool *pool) { } 1925 #endif 1926 1927 /* 1928 * 1929 * Based on the number of unused allocated objects calculate 1930 * and return the number of pages that we can free. 1931 */ 1932 static unsigned long zs_can_compact(struct size_class *class) 1933 { 1934 unsigned long obj_wasted; 1935 unsigned long obj_allocated = class_stat_read(class, ZS_OBJS_ALLOCATED); 1936 unsigned long obj_used = class_stat_read(class, ZS_OBJS_INUSE); 1937 1938 if (obj_allocated <= obj_used) 1939 return 0; 1940 1941 obj_wasted = obj_allocated - obj_used; 1942 obj_wasted /= class->objs_per_zspage; 1943 1944 return obj_wasted * class->pages_per_zspage; 1945 } 1946 1947 static unsigned long __zs_compact(struct zs_pool *pool, 1948 struct size_class *class) 1949 { 1950 struct zspage *src_zspage = NULL; 1951 struct zspage *dst_zspage = NULL; 1952 unsigned long pages_freed = 0; 1953 1954 /* 1955 * protect the race between zpage migration and zs_free 1956 * as well as zpage allocation/free 1957 */ 1958 write_lock(&pool->migrate_lock); 1959 spin_lock(&class->lock); 1960 while (zs_can_compact(class)) { 1961 int fg; 1962 1963 if (!dst_zspage) { 1964 dst_zspage = isolate_dst_zspage(class); 1965 if (!dst_zspage) 1966 break; 1967 } 1968 1969 src_zspage = isolate_src_zspage(class); 1970 if (!src_zspage) 1971 break; 1972 1973 migrate_write_lock(src_zspage); 1974 migrate_zspage(pool, src_zspage, dst_zspage); 1975 migrate_write_unlock(src_zspage); 1976 1977 fg = putback_zspage(class, src_zspage); 1978 if (fg == ZS_INUSE_RATIO_0) { 1979 free_zspage(pool, class, src_zspage); 1980 pages_freed += class->pages_per_zspage; 1981 } 1982 src_zspage = NULL; 1983 1984 if (get_fullness_group(class, dst_zspage) == ZS_INUSE_RATIO_100 1985 || rwlock_is_contended(&pool->migrate_lock)) { 1986 putback_zspage(class, dst_zspage); 1987 dst_zspage = NULL; 1988 1989 spin_unlock(&class->lock); 1990 write_unlock(&pool->migrate_lock); 1991 cond_resched(); 1992 write_lock(&pool->migrate_lock); 1993 spin_lock(&class->lock); 1994 } 1995 } 1996 1997 if (src_zspage) 1998 putback_zspage(class, src_zspage); 1999 2000 if (dst_zspage) 2001 putback_zspage(class, dst_zspage); 2002 2003 spin_unlock(&class->lock); 2004 write_unlock(&pool->migrate_lock); 2005 2006 return pages_freed; 2007 } 2008 2009 unsigned long zs_compact(struct zs_pool *pool) 2010 { 2011 int i; 2012 struct size_class *class; 2013 unsigned long pages_freed = 0; 2014 2015 /* 2016 * Pool compaction is performed under pool->migrate_lock so it is basically 2017 * single-threaded. Having more than one thread in __zs_compact() 2018 * will increase pool->migrate_lock contention, which will impact other 2019 * zsmalloc operations that need pool->migrate_lock. 2020 */ 2021 if (atomic_xchg(&pool->compaction_in_progress, 1)) 2022 return 0; 2023 2024 for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) { 2025 class = pool->size_class[i]; 2026 if (class->index != i) 2027 continue; 2028 pages_freed += __zs_compact(pool, class); 2029 } 2030 atomic_long_add(pages_freed, &pool->stats.pages_compacted); 2031 atomic_set(&pool->compaction_in_progress, 0); 2032 2033 return pages_freed; 2034 } 2035 EXPORT_SYMBOL_GPL(zs_compact); 2036 2037 void zs_pool_stats(struct zs_pool *pool, struct zs_pool_stats *stats) 2038 { 2039 memcpy(stats, &pool->stats, sizeof(struct zs_pool_stats)); 2040 } 2041 EXPORT_SYMBOL_GPL(zs_pool_stats); 2042 2043 static unsigned long zs_shrinker_scan(struct shrinker *shrinker, 2044 struct shrink_control *sc) 2045 { 2046 unsigned long pages_freed; 2047 struct zs_pool *pool = shrinker->private_data; 2048 2049 /* 2050 * Compact classes and calculate compaction delta. 2051 * Can run concurrently with a manually triggered 2052 * (by user) compaction. 2053 */ 2054 pages_freed = zs_compact(pool); 2055 2056 return pages_freed ? pages_freed : SHRINK_STOP; 2057 } 2058 2059 static unsigned long zs_shrinker_count(struct shrinker *shrinker, 2060 struct shrink_control *sc) 2061 { 2062 int i; 2063 struct size_class *class; 2064 unsigned long pages_to_free = 0; 2065 struct zs_pool *pool = shrinker->private_data; 2066 2067 for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) { 2068 class = pool->size_class[i]; 2069 if (class->index != i) 2070 continue; 2071 2072 pages_to_free += zs_can_compact(class); 2073 } 2074 2075 return pages_to_free; 2076 } 2077 2078 static void zs_unregister_shrinker(struct zs_pool *pool) 2079 { 2080 shrinker_free(pool->shrinker); 2081 } 2082 2083 static int zs_register_shrinker(struct zs_pool *pool) 2084 { 2085 pool->shrinker = shrinker_alloc(0, "mm-zspool:%s", pool->name); 2086 if (!pool->shrinker) 2087 return -ENOMEM; 2088 2089 pool->shrinker->scan_objects = zs_shrinker_scan; 2090 pool->shrinker->count_objects = zs_shrinker_count; 2091 pool->shrinker->batch = 0; 2092 pool->shrinker->private_data = pool; 2093 2094 shrinker_register(pool->shrinker); 2095 2096 return 0; 2097 } 2098 2099 static int calculate_zspage_chain_size(int class_size) 2100 { 2101 int i, min_waste = INT_MAX; 2102 int chain_size = 1; 2103 2104 if (is_power_of_2(class_size)) 2105 return chain_size; 2106 2107 for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) { 2108 int waste; 2109 2110 waste = (i * PAGE_SIZE) % class_size; 2111 if (waste < min_waste) { 2112 min_waste = waste; 2113 chain_size = i; 2114 } 2115 } 2116 2117 return chain_size; 2118 } 2119 2120 /** 2121 * zs_create_pool - Creates an allocation pool to work from. 2122 * @name: pool name to be created 2123 * 2124 * This function must be called before anything when using 2125 * the zsmalloc allocator. 2126 * 2127 * On success, a pointer to the newly created pool is returned, 2128 * otherwise NULL. 2129 */ 2130 struct zs_pool *zs_create_pool(const char *name) 2131 { 2132 int i; 2133 struct zs_pool *pool; 2134 struct size_class *prev_class = NULL; 2135 2136 pool = kzalloc(sizeof(*pool), GFP_KERNEL); 2137 if (!pool) 2138 return NULL; 2139 2140 init_deferred_free(pool); 2141 rwlock_init(&pool->migrate_lock); 2142 atomic_set(&pool->compaction_in_progress, 0); 2143 2144 pool->name = kstrdup(name, GFP_KERNEL); 2145 if (!pool->name) 2146 goto err; 2147 2148 if (create_cache(pool)) 2149 goto err; 2150 2151 /* 2152 * Iterate reversely, because, size of size_class that we want to use 2153 * for merging should be larger or equal to current size. 2154 */ 2155 for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) { 2156 int size; 2157 int pages_per_zspage; 2158 int objs_per_zspage; 2159 struct size_class *class; 2160 int fullness; 2161 2162 size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA; 2163 if (size > ZS_MAX_ALLOC_SIZE) 2164 size = ZS_MAX_ALLOC_SIZE; 2165 pages_per_zspage = calculate_zspage_chain_size(size); 2166 objs_per_zspage = pages_per_zspage * PAGE_SIZE / size; 2167 2168 /* 2169 * We iterate from biggest down to smallest classes, 2170 * so huge_class_size holds the size of the first huge 2171 * class. Any object bigger than or equal to that will 2172 * endup in the huge class. 2173 */ 2174 if (pages_per_zspage != 1 && objs_per_zspage != 1 && 2175 !huge_class_size) { 2176 huge_class_size = size; 2177 /* 2178 * The object uses ZS_HANDLE_SIZE bytes to store the 2179 * handle. We need to subtract it, because zs_malloc() 2180 * unconditionally adds handle size before it performs 2181 * size class search - so object may be smaller than 2182 * huge class size, yet it still can end up in the huge 2183 * class because it grows by ZS_HANDLE_SIZE extra bytes 2184 * right before class lookup. 2185 */ 2186 huge_class_size -= (ZS_HANDLE_SIZE - 1); 2187 } 2188 2189 /* 2190 * size_class is used for normal zsmalloc operation such 2191 * as alloc/free for that size. Although it is natural that we 2192 * have one size_class for each size, there is a chance that we 2193 * can get more memory utilization if we use one size_class for 2194 * many different sizes whose size_class have same 2195 * characteristics. So, we makes size_class point to 2196 * previous size_class if possible. 2197 */ 2198 if (prev_class) { 2199 if (can_merge(prev_class, pages_per_zspage, objs_per_zspage)) { 2200 pool->size_class[i] = prev_class; 2201 continue; 2202 } 2203 } 2204 2205 class = kzalloc(sizeof(struct size_class), GFP_KERNEL); 2206 if (!class) 2207 goto err; 2208 2209 class->size = size; 2210 class->index = i; 2211 class->pages_per_zspage = pages_per_zspage; 2212 class->objs_per_zspage = objs_per_zspage; 2213 spin_lock_init(&class->lock); 2214 pool->size_class[i] = class; 2215 2216 fullness = ZS_INUSE_RATIO_0; 2217 while (fullness < NR_FULLNESS_GROUPS) { 2218 INIT_LIST_HEAD(&class->fullness_list[fullness]); 2219 fullness++; 2220 } 2221 2222 prev_class = class; 2223 } 2224 2225 /* debug only, don't abort if it fails */ 2226 zs_pool_stat_create(pool, name); 2227 2228 /* 2229 * Not critical since shrinker is only used to trigger internal 2230 * defragmentation of the pool which is pretty optional thing. If 2231 * registration fails we still can use the pool normally and user can 2232 * trigger compaction manually. Thus, ignore return code. 2233 */ 2234 zs_register_shrinker(pool); 2235 2236 return pool; 2237 2238 err: 2239 zs_destroy_pool(pool); 2240 return NULL; 2241 } 2242 EXPORT_SYMBOL_GPL(zs_create_pool); 2243 2244 void zs_destroy_pool(struct zs_pool *pool) 2245 { 2246 int i; 2247 2248 zs_unregister_shrinker(pool); 2249 zs_flush_migration(pool); 2250 zs_pool_stat_destroy(pool); 2251 2252 for (i = 0; i < ZS_SIZE_CLASSES; i++) { 2253 int fg; 2254 struct size_class *class = pool->size_class[i]; 2255 2256 if (!class) 2257 continue; 2258 2259 if (class->index != i) 2260 continue; 2261 2262 for (fg = ZS_INUSE_RATIO_0; fg < NR_FULLNESS_GROUPS; fg++) { 2263 if (list_empty(&class->fullness_list[fg])) 2264 continue; 2265 2266 pr_err("Class-%d fullness group %d is not empty\n", 2267 class->size, fg); 2268 } 2269 kfree(class); 2270 } 2271 2272 destroy_cache(pool); 2273 kfree(pool->name); 2274 kfree(pool); 2275 } 2276 EXPORT_SYMBOL_GPL(zs_destroy_pool); 2277 2278 static int __init zs_init(void) 2279 { 2280 int ret; 2281 2282 ret = cpuhp_setup_state(CPUHP_MM_ZS_PREPARE, "mm/zsmalloc:prepare", 2283 zs_cpu_prepare, zs_cpu_dead); 2284 if (ret) 2285 goto out; 2286 2287 #ifdef CONFIG_ZPOOL 2288 zpool_register_driver(&zs_zpool_driver); 2289 #endif 2290 2291 zs_stat_init(); 2292 2293 return 0; 2294 2295 out: 2296 return ret; 2297 } 2298 2299 static void __exit zs_exit(void) 2300 { 2301 #ifdef CONFIG_ZPOOL 2302 zpool_unregister_driver(&zs_zpool_driver); 2303 #endif 2304 cpuhp_remove_state(CPUHP_MM_ZS_PREPARE); 2305 2306 zs_stat_exit(); 2307 } 2308 2309 module_init(zs_init); 2310 module_exit(zs_exit); 2311 2312 MODULE_LICENSE("Dual BSD/GPL"); 2313 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>"); 2314 MODULE_DESCRIPTION("zsmalloc memory allocator"); 2315