1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef MM_SLAB_H 3 #define MM_SLAB_H 4 5 #include <linux/reciprocal_div.h> 6 #include <linux/list_lru.h> 7 #include <linux/local_lock.h> 8 #include <linux/random.h> 9 #include <linux/kobject.h> 10 #include <linux/sched/mm.h> 11 #include <linux/memcontrol.h> 12 #include <linux/kfence.h> 13 #include <linux/kasan.h> 14 15 /* 16 * Internal slab definitions 17 */ 18 19 #ifdef CONFIG_64BIT 20 # ifdef system_has_cmpxchg128 21 # define system_has_freelist_aba() system_has_cmpxchg128() 22 # define try_cmpxchg_freelist try_cmpxchg128 23 # endif 24 #define this_cpu_try_cmpxchg_freelist this_cpu_try_cmpxchg128 25 typedef u128 freelist_full_t; 26 #else /* CONFIG_64BIT */ 27 # ifdef system_has_cmpxchg64 28 # define system_has_freelist_aba() system_has_cmpxchg64() 29 # define try_cmpxchg_freelist try_cmpxchg64 30 # endif 31 #define this_cpu_try_cmpxchg_freelist this_cpu_try_cmpxchg64 32 typedef u64 freelist_full_t; 33 #endif /* CONFIG_64BIT */ 34 35 #if defined(system_has_freelist_aba) && !defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE) 36 #undef system_has_freelist_aba 37 #endif 38 39 /* 40 * Freelist pointer and counter to cmpxchg together, avoids the typical ABA 41 * problems with cmpxchg of just a pointer. 42 */ 43 typedef union { 44 struct { 45 void *freelist; 46 unsigned long counter; 47 }; 48 freelist_full_t full; 49 } freelist_aba_t; 50 51 /* Reuses the bits in struct page */ 52 struct slab { 53 unsigned long __page_flags; 54 55 struct kmem_cache *slab_cache; 56 union { 57 struct { 58 union { 59 struct list_head slab_list; 60 #ifdef CONFIG_SLUB_CPU_PARTIAL 61 struct { 62 struct slab *next; 63 int slabs; /* Nr of slabs left */ 64 }; 65 #endif 66 }; 67 /* Double-word boundary */ 68 union { 69 struct { 70 void *freelist; /* first free object */ 71 union { 72 unsigned long counters; 73 struct { 74 unsigned inuse:16; 75 unsigned objects:15; 76 unsigned frozen:1; 77 }; 78 }; 79 }; 80 #ifdef system_has_freelist_aba 81 freelist_aba_t freelist_counter; 82 #endif 83 }; 84 }; 85 struct rcu_head rcu_head; 86 }; 87 unsigned int __unused; 88 89 atomic_t __page_refcount; 90 #ifdef CONFIG_MEMCG 91 unsigned long memcg_data; 92 #endif 93 }; 94 95 #define SLAB_MATCH(pg, sl) \ 96 static_assert(offsetof(struct page, pg) == offsetof(struct slab, sl)) 97 SLAB_MATCH(flags, __page_flags); 98 SLAB_MATCH(compound_head, slab_cache); /* Ensure bit 0 is clear */ 99 SLAB_MATCH(_refcount, __page_refcount); 100 #ifdef CONFIG_MEMCG 101 SLAB_MATCH(memcg_data, memcg_data); 102 #endif 103 #undef SLAB_MATCH 104 static_assert(sizeof(struct slab) <= sizeof(struct page)); 105 #if defined(system_has_freelist_aba) 106 static_assert(IS_ALIGNED(offsetof(struct slab, freelist), sizeof(freelist_aba_t))); 107 #endif 108 109 /** 110 * folio_slab - Converts from folio to slab. 111 * @folio: The folio. 112 * 113 * Currently struct slab is a different representation of a folio where 114 * folio_test_slab() is true. 115 * 116 * Return: The slab which contains this folio. 117 */ 118 #define folio_slab(folio) (_Generic((folio), \ 119 const struct folio *: (const struct slab *)(folio), \ 120 struct folio *: (struct slab *)(folio))) 121 122 /** 123 * slab_folio - The folio allocated for a slab 124 * @slab: The slab. 125 * 126 * Slabs are allocated as folios that contain the individual objects and are 127 * using some fields in the first struct page of the folio - those fields are 128 * now accessed by struct slab. It is occasionally necessary to convert back to 129 * a folio in order to communicate with the rest of the mm. Please use this 130 * helper function instead of casting yourself, as the implementation may change 131 * in the future. 132 */ 133 #define slab_folio(s) (_Generic((s), \ 134 const struct slab *: (const struct folio *)s, \ 135 struct slab *: (struct folio *)s)) 136 137 /** 138 * page_slab - Converts from first struct page to slab. 139 * @p: The first (either head of compound or single) page of slab. 140 * 141 * A temporary wrapper to convert struct page to struct slab in situations where 142 * we know the page is the compound head, or single order-0 page. 143 * 144 * Long-term ideally everything would work with struct slab directly or go 145 * through folio to struct slab. 146 * 147 * Return: The slab which contains this page 148 */ 149 #define page_slab(p) (_Generic((p), \ 150 const struct page *: (const struct slab *)(p), \ 151 struct page *: (struct slab *)(p))) 152 153 /** 154 * slab_page - The first struct page allocated for a slab 155 * @slab: The slab. 156 * 157 * A convenience wrapper for converting slab to the first struct page of the 158 * underlying folio, to communicate with code not yet converted to folio or 159 * struct slab. 160 */ 161 #define slab_page(s) folio_page(slab_folio(s), 0) 162 163 /* 164 * If network-based swap is enabled, sl*b must keep track of whether pages 165 * were allocated from pfmemalloc reserves. 166 */ 167 static inline bool slab_test_pfmemalloc(const struct slab *slab) 168 { 169 return folio_test_active((struct folio *)slab_folio(slab)); 170 } 171 172 static inline void slab_set_pfmemalloc(struct slab *slab) 173 { 174 folio_set_active(slab_folio(slab)); 175 } 176 177 static inline void slab_clear_pfmemalloc(struct slab *slab) 178 { 179 folio_clear_active(slab_folio(slab)); 180 } 181 182 static inline void __slab_clear_pfmemalloc(struct slab *slab) 183 { 184 __folio_clear_active(slab_folio(slab)); 185 } 186 187 static inline void *slab_address(const struct slab *slab) 188 { 189 return folio_address(slab_folio(slab)); 190 } 191 192 static inline int slab_nid(const struct slab *slab) 193 { 194 return folio_nid(slab_folio(slab)); 195 } 196 197 static inline pg_data_t *slab_pgdat(const struct slab *slab) 198 { 199 return folio_pgdat(slab_folio(slab)); 200 } 201 202 static inline struct slab *virt_to_slab(const void *addr) 203 { 204 struct folio *folio = virt_to_folio(addr); 205 206 if (!folio_test_slab(folio)) 207 return NULL; 208 209 return folio_slab(folio); 210 } 211 212 static inline int slab_order(const struct slab *slab) 213 { 214 return folio_order((struct folio *)slab_folio(slab)); 215 } 216 217 static inline size_t slab_size(const struct slab *slab) 218 { 219 return PAGE_SIZE << slab_order(slab); 220 } 221 222 #ifdef CONFIG_SLUB_CPU_PARTIAL 223 #define slub_percpu_partial(c) ((c)->partial) 224 225 #define slub_set_percpu_partial(c, p) \ 226 ({ \ 227 slub_percpu_partial(c) = (p)->next; \ 228 }) 229 230 #define slub_percpu_partial_read_once(c) READ_ONCE(slub_percpu_partial(c)) 231 #else 232 #define slub_percpu_partial(c) NULL 233 234 #define slub_set_percpu_partial(c, p) 235 236 #define slub_percpu_partial_read_once(c) NULL 237 #endif // CONFIG_SLUB_CPU_PARTIAL 238 239 /* 240 * Word size structure that can be atomically updated or read and that 241 * contains both the order and the number of objects that a slab of the 242 * given order would contain. 243 */ 244 struct kmem_cache_order_objects { 245 unsigned int x; 246 }; 247 248 /* 249 * Slab cache management. 250 */ 251 struct kmem_cache { 252 #ifndef CONFIG_SLUB_TINY 253 struct kmem_cache_cpu __percpu *cpu_slab; 254 #endif 255 /* Used for retrieving partial slabs, etc. */ 256 slab_flags_t flags; 257 unsigned long min_partial; 258 unsigned int size; /* Object size including metadata */ 259 unsigned int object_size; /* Object size without metadata */ 260 struct reciprocal_value reciprocal_size; 261 unsigned int offset; /* Free pointer offset */ 262 #ifdef CONFIG_SLUB_CPU_PARTIAL 263 /* Number of per cpu partial objects to keep around */ 264 unsigned int cpu_partial; 265 /* Number of per cpu partial slabs to keep around */ 266 unsigned int cpu_partial_slabs; 267 #endif 268 struct kmem_cache_order_objects oo; 269 270 /* Allocation and freeing of slabs */ 271 struct kmem_cache_order_objects min; 272 gfp_t allocflags; /* gfp flags to use on each alloc */ 273 int refcount; /* Refcount for slab cache destroy */ 274 void (*ctor)(void *object); /* Object constructor */ 275 unsigned int inuse; /* Offset to metadata */ 276 unsigned int align; /* Alignment */ 277 unsigned int red_left_pad; /* Left redzone padding size */ 278 const char *name; /* Name (only for display!) */ 279 struct list_head list; /* List of slab caches */ 280 #ifdef CONFIG_SYSFS 281 struct kobject kobj; /* For sysfs */ 282 #endif 283 #ifdef CONFIG_SLAB_FREELIST_HARDENED 284 unsigned long random; 285 #endif 286 287 #ifdef CONFIG_NUMA 288 /* 289 * Defragmentation by allocating from a remote node. 290 */ 291 unsigned int remote_node_defrag_ratio; 292 #endif 293 294 #ifdef CONFIG_SLAB_FREELIST_RANDOM 295 unsigned int *random_seq; 296 #endif 297 298 #ifdef CONFIG_KASAN_GENERIC 299 struct kasan_cache kasan_info; 300 #endif 301 302 #ifdef CONFIG_HARDENED_USERCOPY 303 unsigned int useroffset; /* Usercopy region offset */ 304 unsigned int usersize; /* Usercopy region size */ 305 #endif 306 307 struct kmem_cache_node *node[MAX_NUMNODES]; 308 }; 309 310 #if defined(CONFIG_SYSFS) && !defined(CONFIG_SLUB_TINY) 311 #define SLAB_SUPPORTS_SYSFS 312 void sysfs_slab_unlink(struct kmem_cache *s); 313 void sysfs_slab_release(struct kmem_cache *s); 314 #else 315 static inline void sysfs_slab_unlink(struct kmem_cache *s) { } 316 static inline void sysfs_slab_release(struct kmem_cache *s) { } 317 #endif 318 319 void *fixup_red_left(struct kmem_cache *s, void *p); 320 321 static inline void *nearest_obj(struct kmem_cache *cache, 322 const struct slab *slab, void *x) 323 { 324 void *object = x - (x - slab_address(slab)) % cache->size; 325 void *last_object = slab_address(slab) + 326 (slab->objects - 1) * cache->size; 327 void *result = (unlikely(object > last_object)) ? last_object : object; 328 329 result = fixup_red_left(cache, result); 330 return result; 331 } 332 333 /* Determine object index from a given position */ 334 static inline unsigned int __obj_to_index(const struct kmem_cache *cache, 335 void *addr, void *obj) 336 { 337 return reciprocal_divide(kasan_reset_tag(obj) - addr, 338 cache->reciprocal_size); 339 } 340 341 static inline unsigned int obj_to_index(const struct kmem_cache *cache, 342 const struct slab *slab, void *obj) 343 { 344 if (is_kfence_address(obj)) 345 return 0; 346 return __obj_to_index(cache, slab_address(slab), obj); 347 } 348 349 static inline int objs_per_slab(const struct kmem_cache *cache, 350 const struct slab *slab) 351 { 352 return slab->objects; 353 } 354 355 /* 356 * State of the slab allocator. 357 * 358 * This is used to describe the states of the allocator during bootup. 359 * Allocators use this to gradually bootstrap themselves. Most allocators 360 * have the problem that the structures used for managing slab caches are 361 * allocated from slab caches themselves. 362 */ 363 enum slab_state { 364 DOWN, /* No slab functionality yet */ 365 PARTIAL, /* SLUB: kmem_cache_node available */ 366 UP, /* Slab caches usable but not all extras yet */ 367 FULL /* Everything is working */ 368 }; 369 370 extern enum slab_state slab_state; 371 372 /* The slab cache mutex protects the management structures during changes */ 373 extern struct mutex slab_mutex; 374 375 /* The list of all slab caches on the system */ 376 extern struct list_head slab_caches; 377 378 /* The slab cache that manages slab cache information */ 379 extern struct kmem_cache *kmem_cache; 380 381 /* A table of kmalloc cache names and sizes */ 382 extern const struct kmalloc_info_struct { 383 const char *name[NR_KMALLOC_TYPES]; 384 unsigned int size; 385 } kmalloc_info[]; 386 387 /* Kmalloc array related functions */ 388 void setup_kmalloc_cache_index_table(void); 389 void create_kmalloc_caches(void); 390 391 extern u8 kmalloc_size_index[24]; 392 393 static inline unsigned int size_index_elem(unsigned int bytes) 394 { 395 return (bytes - 1) / 8; 396 } 397 398 /* 399 * Find the kmem_cache structure that serves a given size of 400 * allocation 401 * 402 * This assumes size is larger than zero and not larger than 403 * KMALLOC_MAX_CACHE_SIZE and the caller must check that. 404 */ 405 static inline struct kmem_cache * 406 kmalloc_slab(size_t size, gfp_t flags, unsigned long caller) 407 { 408 unsigned int index; 409 410 if (size <= 192) 411 index = kmalloc_size_index[size_index_elem(size)]; 412 else 413 index = fls(size - 1); 414 415 return kmalloc_caches[kmalloc_type(flags, caller)][index]; 416 } 417 418 gfp_t kmalloc_fix_flags(gfp_t flags); 419 420 /* Functions provided by the slab allocators */ 421 int __kmem_cache_create(struct kmem_cache *, slab_flags_t flags); 422 423 void __init kmem_cache_init(void); 424 extern void create_boot_cache(struct kmem_cache *, const char *name, 425 unsigned int size, slab_flags_t flags, 426 unsigned int useroffset, unsigned int usersize); 427 428 int slab_unmergeable(struct kmem_cache *s); 429 struct kmem_cache *find_mergeable(unsigned size, unsigned align, 430 slab_flags_t flags, const char *name, void (*ctor)(void *)); 431 struct kmem_cache * 432 __kmem_cache_alias(const char *name, unsigned int size, unsigned int align, 433 slab_flags_t flags, void (*ctor)(void *)); 434 435 slab_flags_t kmem_cache_flags(slab_flags_t flags, const char *name); 436 437 static inline bool is_kmalloc_cache(struct kmem_cache *s) 438 { 439 return (s->flags & SLAB_KMALLOC); 440 } 441 442 /* Legal flag mask for kmem_cache_create(), for various configurations */ 443 #define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | \ 444 SLAB_CACHE_DMA32 | SLAB_PANIC | \ 445 SLAB_TYPESAFE_BY_RCU | SLAB_DEBUG_OBJECTS ) 446 447 #ifdef CONFIG_SLUB_DEBUG 448 #define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \ 449 SLAB_TRACE | SLAB_CONSISTENCY_CHECKS) 450 #else 451 #define SLAB_DEBUG_FLAGS (0) 452 #endif 453 454 #define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE | SLAB_RECLAIM_ACCOUNT | \ 455 SLAB_TEMPORARY | SLAB_ACCOUNT | \ 456 SLAB_NO_USER_FLAGS | SLAB_KMALLOC | SLAB_NO_MERGE) 457 458 /* Common flags available with current configuration */ 459 #define CACHE_CREATE_MASK (SLAB_CORE_FLAGS | SLAB_DEBUG_FLAGS | SLAB_CACHE_FLAGS) 460 461 /* Common flags permitted for kmem_cache_create */ 462 #define SLAB_FLAGS_PERMITTED (SLAB_CORE_FLAGS | \ 463 SLAB_RED_ZONE | \ 464 SLAB_POISON | \ 465 SLAB_STORE_USER | \ 466 SLAB_TRACE | \ 467 SLAB_CONSISTENCY_CHECKS | \ 468 SLAB_NOLEAKTRACE | \ 469 SLAB_RECLAIM_ACCOUNT | \ 470 SLAB_TEMPORARY | \ 471 SLAB_ACCOUNT | \ 472 SLAB_KMALLOC | \ 473 SLAB_NO_MERGE | \ 474 SLAB_NO_USER_FLAGS) 475 476 bool __kmem_cache_empty(struct kmem_cache *); 477 int __kmem_cache_shutdown(struct kmem_cache *); 478 void __kmem_cache_release(struct kmem_cache *); 479 int __kmem_cache_shrink(struct kmem_cache *); 480 void slab_kmem_cache_release(struct kmem_cache *); 481 482 struct seq_file; 483 struct file; 484 485 struct slabinfo { 486 unsigned long active_objs; 487 unsigned long num_objs; 488 unsigned long active_slabs; 489 unsigned long num_slabs; 490 unsigned long shared_avail; 491 unsigned int limit; 492 unsigned int batchcount; 493 unsigned int shared; 494 unsigned int objects_per_slab; 495 unsigned int cache_order; 496 }; 497 498 void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo); 499 void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s); 500 ssize_t slabinfo_write(struct file *file, const char __user *buffer, 501 size_t count, loff_t *ppos); 502 503 #ifdef CONFIG_SLUB_DEBUG 504 #ifdef CONFIG_SLUB_DEBUG_ON 505 DECLARE_STATIC_KEY_TRUE(slub_debug_enabled); 506 #else 507 DECLARE_STATIC_KEY_FALSE(slub_debug_enabled); 508 #endif 509 extern void print_tracking(struct kmem_cache *s, void *object); 510 long validate_slab_cache(struct kmem_cache *s); 511 static inline bool __slub_debug_enabled(void) 512 { 513 return static_branch_unlikely(&slub_debug_enabled); 514 } 515 #else 516 static inline void print_tracking(struct kmem_cache *s, void *object) 517 { 518 } 519 static inline bool __slub_debug_enabled(void) 520 { 521 return false; 522 } 523 #endif 524 525 /* 526 * Returns true if any of the specified slab_debug flags is enabled for the 527 * cache. Use only for flags parsed by setup_slub_debug() as it also enables 528 * the static key. 529 */ 530 static inline bool kmem_cache_debug_flags(struct kmem_cache *s, slab_flags_t flags) 531 { 532 if (IS_ENABLED(CONFIG_SLUB_DEBUG)) 533 VM_WARN_ON_ONCE(!(flags & SLAB_DEBUG_FLAGS)); 534 if (__slub_debug_enabled()) 535 return s->flags & flags; 536 return false; 537 } 538 539 #ifdef CONFIG_MEMCG_KMEM 540 /* 541 * slab_objcgs - get the object cgroups vector associated with a slab 542 * @slab: a pointer to the slab struct 543 * 544 * Returns a pointer to the object cgroups vector associated with the slab, 545 * or NULL if no such vector has been associated yet. 546 */ 547 static inline struct obj_cgroup **slab_objcgs(struct slab *slab) 548 { 549 unsigned long memcg_data = READ_ONCE(slab->memcg_data); 550 551 VM_BUG_ON_PAGE(memcg_data && !(memcg_data & MEMCG_DATA_OBJCGS), 552 slab_page(slab)); 553 VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_KMEM, slab_page(slab)); 554 555 return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK); 556 } 557 558 int memcg_alloc_slab_cgroups(struct slab *slab, struct kmem_cache *s, 559 gfp_t gfp, bool new_slab); 560 void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, 561 enum node_stat_item idx, int nr); 562 #else /* CONFIG_MEMCG_KMEM */ 563 static inline struct obj_cgroup **slab_objcgs(struct slab *slab) 564 { 565 return NULL; 566 } 567 568 static inline int memcg_alloc_slab_cgroups(struct slab *slab, 569 struct kmem_cache *s, gfp_t gfp, 570 bool new_slab) 571 { 572 return 0; 573 } 574 #endif /* CONFIG_MEMCG_KMEM */ 575 576 size_t __ksize(const void *objp); 577 578 static inline size_t slab_ksize(const struct kmem_cache *s) 579 { 580 #ifdef CONFIG_SLUB_DEBUG 581 /* 582 * Debugging requires use of the padding between object 583 * and whatever may come after it. 584 */ 585 if (s->flags & (SLAB_RED_ZONE | SLAB_POISON)) 586 return s->object_size; 587 #endif 588 if (s->flags & SLAB_KASAN) 589 return s->object_size; 590 /* 591 * If we have the need to store the freelist pointer 592 * back there or track user information then we can 593 * only use the space before that information. 594 */ 595 if (s->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_STORE_USER)) 596 return s->inuse; 597 /* 598 * Else we can use all the padding etc for the allocation 599 */ 600 return s->size; 601 } 602 603 #ifdef CONFIG_SLUB_DEBUG 604 void dump_unreclaimable_slab(void); 605 #else 606 static inline void dump_unreclaimable_slab(void) 607 { 608 } 609 #endif 610 611 void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr); 612 613 #ifdef CONFIG_SLAB_FREELIST_RANDOM 614 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count, 615 gfp_t gfp); 616 void cache_random_seq_destroy(struct kmem_cache *cachep); 617 #else 618 static inline int cache_random_seq_create(struct kmem_cache *cachep, 619 unsigned int count, gfp_t gfp) 620 { 621 return 0; 622 } 623 static inline void cache_random_seq_destroy(struct kmem_cache *cachep) { } 624 #endif /* CONFIG_SLAB_FREELIST_RANDOM */ 625 626 static inline bool slab_want_init_on_alloc(gfp_t flags, struct kmem_cache *c) 627 { 628 if (static_branch_maybe(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, 629 &init_on_alloc)) { 630 if (c->ctor) 631 return false; 632 if (c->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)) 633 return flags & __GFP_ZERO; 634 return true; 635 } 636 return flags & __GFP_ZERO; 637 } 638 639 static inline bool slab_want_init_on_free(struct kmem_cache *c) 640 { 641 if (static_branch_maybe(CONFIG_INIT_ON_FREE_DEFAULT_ON, 642 &init_on_free)) 643 return !(c->ctor || 644 (c->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON))); 645 return false; 646 } 647 648 #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_SLUB_DEBUG) 649 void debugfs_slab_release(struct kmem_cache *); 650 #else 651 static inline void debugfs_slab_release(struct kmem_cache *s) { } 652 #endif 653 654 #ifdef CONFIG_PRINTK 655 #define KS_ADDRS_COUNT 16 656 struct kmem_obj_info { 657 void *kp_ptr; 658 struct slab *kp_slab; 659 void *kp_objp; 660 unsigned long kp_data_offset; 661 struct kmem_cache *kp_slab_cache; 662 void *kp_ret; 663 void *kp_stack[KS_ADDRS_COUNT]; 664 void *kp_free_stack[KS_ADDRS_COUNT]; 665 }; 666 void __kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab); 667 #endif 668 669 void __check_heap_object(const void *ptr, unsigned long n, 670 const struct slab *slab, bool to_user); 671 672 #ifdef CONFIG_SLUB_DEBUG 673 void skip_orig_size_check(struct kmem_cache *s, const void *object); 674 #endif 675 676 #endif /* MM_SLAB_H */ 677