include/linux/slab.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Written by Mark Hemment, 1996 (markhe@nextd.demon.co.uk).
   4  *
   5  * (C) SGI 2006, Christoph Lameter
   6  *      Cleaned up and restructured to ease the addition of alternative
   7  *      implementations of SLAB allocators.
   8  * (C) Linux Foundation 2008-2013
   9  *      Unified interface for all slab allocators
  10  */
  11
  12 #ifndef _LINUX_SLAB_H
  13 #define _LINUX_SLAB_H
  14
  15 #include <linux/gfp.h>
  16 #include <linux/overflow.h>
  17 #include <linux/types.h>
  18 #include <linux/workqueue.h>
  19
  20
  21 /*
  22  * Flags to pass to kmem_cache_create().
  23  * The ones marked DEBUG are only valid if CONFIG_DEBUG_SLAB is set.
  24  */
  25 /* DEBUG: Perform (expensive) checks on alloc/free */
  26 #define SLAB_CONSISTENCY_CHECKS ((slab_flags_t __force)0x00000100U)
  27 /* DEBUG: Red zone objs in a cache */
  28 #define SLAB_RED_ZONE           ((slab_flags_t __force)0x00000400U)
  29 /* DEBUG: Poison objects */
  30 #define SLAB_POISON             ((slab_flags_t __force)0x00000800U)
  31 /* Align objs on cache lines */
  32 #define SLAB_HWCACHE_ALIGN      ((slab_flags_t __force)0x00002000U)
  33 /* Use GFP_DMA memory */
  34 #define SLAB_CACHE_DMA          ((slab_flags_t __force)0x00004000U)
  35 /* DEBUG: Store the last owner for bug hunting */
  36 #define SLAB_STORE_USER         ((slab_flags_t __force)0x00010000U)
  37 /* Panic if kmem_cache_create() fails */
  38 #define SLAB_PANIC              ((slab_flags_t __force)0x00040000U)
  39 /*
  40  * SLAB_TYPESAFE_BY_RCU - **WARNING** READ THIS!
  41  *
  42  * This delays freeing the SLAB page by a grace period, it does _NOT_
  43  * delay object freeing. This means that if you do kmem_cache_free()
  44  * that memory location is free to be reused at any time. Thus it may
  45  * be possible to see another object there in the same RCU grace period.
  46  *
  47  * This feature only ensures the memory location backing the object
  48  * stays valid, the trick to using this is relying on an independent
  49  * object validation pass. Something like:
  50  *
  51  *  rcu_read_lock()
  52  * again:
  53  *  obj = lockless_lookup(key);
  54  *  if (obj) {
  55  *    if (!try_get_ref(obj)) // might fail for free objects
  56  *      goto again;
  57  *
  58  *    if (obj->key != key) { // not the object we expected
  59  *      put_ref(obj);
  60  *      goto again;
  61  *    }
  62  *  }
  63  *  rcu_read_unlock();
  64  *
  65  * This is useful if we need to approach a kernel structure obliquely,
  66  * from its address obtained without the usual locking. We can lock
  67  * the structure to stabilize it and check it's still at the given address,
  68  * only if we can be sure that the memory has not been meanwhile reused
  69  * for some other kind of object (which our subsystem's lock might corrupt).
  70  *
  71  * rcu_read_lock before reading the address, then rcu_read_unlock after
  72  * taking the spinlock within the structure expected at that address.
  73  *
  74  * Note that SLAB_TYPESAFE_BY_RCU was originally named SLAB_DESTROY_BY_RCU.
  75  */
  76 /* Defer freeing slabs to RCU */
  77 #define SLAB_TYPESAFE_BY_RCU    ((slab_flags_t __force)0x00080000U)
  78 /* Spread some memory over cpuset */
  79 #define SLAB_MEM_SPREAD         ((slab_flags_t __force)0x00100000U)
  80 /* Trace allocations and frees */
  81 #define SLAB_TRACE              ((slab_flags_t __force)0x00200000U)
  82
  83 /* Flag to prevent checks on free */
  84 #ifdef CONFIG_DEBUG_OBJECTS
  85 # define SLAB_DEBUG_OBJECTS     ((slab_flags_t __force)0x00400000U)
  86 #else
  87 # define SLAB_DEBUG_OBJECTS     0
  88 #endif
  89
  90 /* Avoid kmemleak tracing */
  91 #define SLAB_NOLEAKTRACE        ((slab_flags_t __force)0x00800000U)
  92
  93 /* Fault injection mark */
  94 #ifdef CONFIG_FAILSLAB
  95 # define SLAB_FAILSLAB          ((slab_flags_t __force)0x02000000U)
  96 #else
  97 # define SLAB_FAILSLAB          0
  98 #endif
  99 /* Account to memcg */
 100 #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
 101 # define SLAB_ACCOUNT           ((slab_flags_t __force)0x04000000U)
 102 #else
 103 # define SLAB_ACCOUNT           0
 104 #endif
 105
 106 #ifdef CONFIG_KASAN
 107 #define SLAB_KASAN              ((slab_flags_t __force)0x08000000U)
 108 #else
 109 #define SLAB_KASAN              0
 110 #endif
 111
 112 /* The following flags affect the page allocator grouping pages by mobility */
 113 /* Objects are reclaimable */
 114 #define SLAB_RECLAIM_ACCOUNT    ((slab_flags_t __force)0x00020000U)
 115 #define SLAB_TEMPORARY          SLAB_RECLAIM_ACCOUNT    /* Objects are short-lived */
 116 /*
 117  * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
 118  *
 119  * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
 120  *
 121  * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
 122  * Both make kfree a no-op.
 123  */
 124 #define ZERO_SIZE_PTR ((void *)16)
 125
 126 #define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
 127                                 (unsigned long)ZERO_SIZE_PTR)
 128
 129 #include <linux/kasan.h>
 130
 131 struct mem_cgroup;
 132 /*
 133  * struct kmem_cache related prototypes
 134  */
 135 void __init kmem_cache_init(void);
 136 bool slab_is_available(void);
 137
 138 extern bool usercopy_fallback;
 139
 140 struct kmem_cache *kmem_cache_create(const char *name, unsigned int size,
 141                         unsigned int align, slab_flags_t flags,
 142                         void (*ctor)(void *));
 143 struct kmem_cache *kmem_cache_create_usercopy(const char *name,
 144                         unsigned int size, unsigned int align,
 145                         slab_flags_t flags,
 146                         unsigned int useroffset, unsigned int usersize,
 147                         void (*ctor)(void *));
 148 void kmem_cache_destroy(struct kmem_cache *);
 149 int kmem_cache_shrink(struct kmem_cache *);
 150
 151 void memcg_create_kmem_cache(struct mem_cgroup *, struct kmem_cache *);
 152 void memcg_deactivate_kmem_caches(struct mem_cgroup *);
 153 void memcg_destroy_kmem_caches(struct mem_cgroup *);
 154
 155 /*
 156  * Please use this macro to create slab caches. Simply specify the
 157  * name of the structure and maybe some flags that are listed above.
 158  *
 159  * The alignment of the struct determines object alignment. If you
 160  * f.e. add ____cacheline_aligned_in_smp to the struct declaration
 161  * then the objects will be properly aligned in SMP configurations.
 162  */
 163 #define KMEM_CACHE(__struct, __flags)                                   \
 164                 kmem_cache_create(#__struct, sizeof(struct __struct),   \
 165                         __alignof__(struct __struct), (__flags), NULL)
 166
 167 /*
 168  * To whitelist a single field for copying to/from usercopy, use this
 169  * macro instead for KMEM_CACHE() above.
 170  */
 171 #define KMEM_CACHE_USERCOPY(__struct, __flags, __field)                 \
 172                 kmem_cache_create_usercopy(#__struct,                   \
 173                         sizeof(struct __struct),                        \
 174                         __alignof__(struct __struct), (__flags),        \
 175                         offsetof(struct __struct, __field),             \
 176                         sizeof_field(struct __struct, __field), NULL)
 177
 178 /*
 179  * Common kmalloc functions provided by all allocators
 180  */
 181 void * __must_check __krealloc(const void *, size_t, gfp_t);
 182 void * __must_check krealloc(const void *, size_t, gfp_t);
 183 void kfree(const void *);
 184 void kzfree(const void *);
 185 size_t ksize(const void *);
 186
 187 #ifdef CONFIG_HAVE_HARDENED_USERCOPY_ALLOCATOR
 188 void __check_heap_object(const void *ptr, unsigned long n, struct page *page,
 189                         bool to_user);
 190 #else
 191 static inline void __check_heap_object(const void *ptr, unsigned long n,
 192                                        struct page *page, bool to_user) { }
 193 #endif
 194
 195 /*
 196  * Some archs want to perform DMA into kmalloc caches and need a guaranteed
 197  * alignment larger than the alignment of a 64-bit integer.
 198  * Setting ARCH_KMALLOC_MINALIGN in arch headers allows that.
 199  */
 200 #if defined(ARCH_DMA_MINALIGN) && ARCH_DMA_MINALIGN > 8
 201 #define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
 202 #define KMALLOC_MIN_SIZE ARCH_DMA_MINALIGN
 203 #define KMALLOC_SHIFT_LOW ilog2(ARCH_DMA_MINALIGN)
 204 #else
 205 #define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
 206 #endif
 207
 208 /*
 209  * Setting ARCH_SLAB_MINALIGN in arch headers allows a different alignment.
 210  * Intended for arches that get misalignment faults even for 64 bit integer
 211  * aligned buffers.
 212  */
 213 #ifndef ARCH_SLAB_MINALIGN
 214 #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
 215 #endif
 216
 217 /*
 218  * kmalloc and friends return ARCH_KMALLOC_MINALIGN aligned
 219  * pointers. kmem_cache_alloc and friends return ARCH_SLAB_MINALIGN
 220  * aligned pointers.
 221  */
 222 #define __assume_kmalloc_alignment __assume_aligned(ARCH_KMALLOC_MINALIGN)
 223 #define __assume_slab_alignment __assume_aligned(ARCH_SLAB_MINALIGN)
 224 #define __assume_page_alignment __assume_aligned(PAGE_SIZE)
 225
 226 /*
 227  * Kmalloc array related definitions
 228  */
 229
 230 #ifdef CONFIG_SLAB
 231 /*
 232  * The largest kmalloc size supported by the SLAB allocators is
 233  * 32 megabyte (2^25) or the maximum allocatable page order if that is
 234  * less than 32 MB.
 235  *
 236  * WARNING: Its not easy to increase this value since the allocators have
 237  * to do various tricks to work around compiler limitations in order to
 238  * ensure proper constant folding.
 239  */
 240 #define KMALLOC_SHIFT_HIGH      ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
 241                                 (MAX_ORDER + PAGE_SHIFT - 1) : 25)
 242 #define KMALLOC_SHIFT_MAX       KMALLOC_SHIFT_HIGH
 243 #ifndef KMALLOC_SHIFT_LOW
 244 #define KMALLOC_SHIFT_LOW       5
 245 #endif
 246 #endif
 247
 248 #ifdef CONFIG_SLUB
 249 /*
 250  * SLUB directly allocates requests fitting in to an order-1 page
 251  * (PAGE_SIZE*2).  Larger requests are passed to the page allocator.
 252  */
 253 #define KMALLOC_SHIFT_HIGH      (PAGE_SHIFT + 1)
 254 #define KMALLOC_SHIFT_MAX       (MAX_ORDER + PAGE_SHIFT - 1)
 255 #ifndef KMALLOC_SHIFT_LOW
 256 #define KMALLOC_SHIFT_LOW       3
 257 #endif
 258 #endif
 259
 260 #ifdef CONFIG_SLOB
 261 /*
 262  * SLOB passes all requests larger than one page to the page allocator.
 263  * No kmalloc array is necessary since objects of different sizes can
 264  * be allocated from the same page.
 265  */
 266 #define KMALLOC_SHIFT_HIGH      PAGE_SHIFT
 267 #define KMALLOC_SHIFT_MAX       (MAX_ORDER + PAGE_SHIFT - 1)
 268 #ifndef KMALLOC_SHIFT_LOW
 269 #define KMALLOC_SHIFT_LOW       3
 270 #endif
 271 #endif
 272
 273 /* Maximum allocatable size */
 274 #define KMALLOC_MAX_SIZE        (1UL << KMALLOC_SHIFT_MAX)
 275 /* Maximum size for which we actually use a slab cache */
 276 #define KMALLOC_MAX_CACHE_SIZE  (1UL << KMALLOC_SHIFT_HIGH)
 277 /* Maximum order allocatable via the slab allocagtor */
 278 #define KMALLOC_MAX_ORDER       (KMALLOC_SHIFT_MAX - PAGE_SHIFT)
 279
 280 /*
 281  * Kmalloc subsystem.
 282  */
 283 #ifndef KMALLOC_MIN_SIZE
 284 #define KMALLOC_MIN_SIZE (1 << KMALLOC_SHIFT_LOW)
 285 #endif
 286
 287 /*
 288  * This restriction comes from byte sized index implementation.
 289  * Page size is normally 2^12 bytes and, in this case, if we want to use
 290  * byte sized index which can represent 2^8 entries, the size of the object
 291  * should be equal or greater to 2^12 / 2^8 = 2^4 = 16.
 292  * If minimum size of kmalloc is less than 16, we use it as minimum object
 293  * size and give up to use byte sized index.
 294  */
 295 #define SLAB_OBJ_MIN_SIZE      (KMALLOC_MIN_SIZE < 16 ? \
 296                                (KMALLOC_MIN_SIZE) : 16)
 297
 298 #ifndef CONFIG_SLOB
 299 extern struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
 300 #ifdef CONFIG_ZONE_DMA
 301 extern struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
 302 #endif
 303
 304 /*
 305  * Figure out which kmalloc slab an allocation of a certain size
 306  * belongs to.
 307  * 0 = zero alloc
 308  * 1 =  65 .. 96 bytes
 309  * 2 = 129 .. 192 bytes
 310  * n = 2^(n-1)+1 .. 2^n
 311  */
 312 static __always_inline unsigned int kmalloc_index(size_t size)
 313 {
 314         if (!size)
 315                 return 0;
 316
 317         if (size <= KMALLOC_MIN_SIZE)
 318                 return KMALLOC_SHIFT_LOW;
 319
 320         if (KMALLOC_MIN_SIZE <= 32 && size > 64 && size <= 96)
 321                 return 1;
 322         if (KMALLOC_MIN_SIZE <= 64 && size > 128 && size <= 192)
 323                 return 2;
 324         if (size <=          8) return 3;
 325         if (size <=         16) return 4;
 326         if (size <=         32) return 5;
 327         if (size <=         64) return 6;
 328         if (size <=        128) return 7;
 329         if (size <=        256) return 8;
 330         if (size <=        512) return 9;
 331         if (size <=       1024) return 10;
 332         if (size <=   2 * 1024) return 11;
 333         if (size <=   4 * 1024) return 12;
 334         if (size <=   8 * 1024) return 13;
 335         if (size <=  16 * 1024) return 14;
 336         if (size <=  32 * 1024) return 15;
 337         if (size <=  64 * 1024) return 16;
 338         if (size <= 128 * 1024) return 17;
 339         if (size <= 256 * 1024) return 18;
 340         if (size <= 512 * 1024) return 19;
 341         if (size <= 1024 * 1024) return 20;
 342         if (size <=  2 * 1024 * 1024) return 21;
 343         if (size <=  4 * 1024 * 1024) return 22;
 344         if (size <=  8 * 1024 * 1024) return 23;
 345         if (size <=  16 * 1024 * 1024) return 24;
 346         if (size <=  32 * 1024 * 1024) return 25;
 347         if (size <=  64 * 1024 * 1024) return 26;
 348         BUG();
 349
 350         /* Will never be reached. Needed because the compiler may complain */
 351         return -1;
 352 }
 353 #endif /* !CONFIG_SLOB */
 354
 355 void *__kmalloc(size_t size, gfp_t flags) __assume_kmalloc_alignment __malloc;
 356 void *kmem_cache_alloc(struct kmem_cache *, gfp_t flags) __assume_slab_alignment __malloc;
 357 void kmem_cache_free(struct kmem_cache *, void *);
 358
 359 /*
 360  * Bulk allocation and freeing operations. These are accelerated in an
 361  * allocator specific way to avoid taking locks repeatedly or building
 362  * metadata structures unnecessarily.
 363  *
 364  * Note that interrupts must be enabled when calling these functions.
 365  */
 366 void kmem_cache_free_bulk(struct kmem_cache *, size_t, void **);
 367 int kmem_cache_alloc_bulk(struct kmem_cache *, gfp_t, size_t, void **);
 368
 369 /*
 370  * Caller must not use kfree_bulk() on memory not originally allocated
 371  * by kmalloc(), because the SLOB allocator cannot handle this.
 372  */
 373 static __always_inline void kfree_bulk(size_t size, void **p)
 374 {
 375         kmem_cache_free_bulk(NULL, size, p);
 376 }
 377
 378 #ifdef CONFIG_NUMA
 379 void *__kmalloc_node(size_t size, gfp_t flags, int node) __assume_kmalloc_alignment __malloc;
 380 void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node) __assume_slab_alignment __malloc;
 381 #else
 382 static __always_inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
 383 {
 384         return __kmalloc(size, flags);
 385 }
 386
 387 static __always_inline void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t flags, int node)
 388 {
 389         return kmem_cache_alloc(s, flags);
 390 }
 391 #endif
 392
 393 #ifdef CONFIG_TRACING
 394 extern void *kmem_cache_alloc_trace(struct kmem_cache *, gfp_t, size_t) __assume_slab_alignment __malloc;
 395
 396 #ifdef CONFIG_NUMA
 397 extern void *kmem_cache_alloc_node_trace(struct kmem_cache *s,
 398                                            gfp_t gfpflags,
 399                                            int node, size_t size) __assume_slab_alignment __malloc;
 400 #else
 401 static __always_inline void *
 402 kmem_cache_alloc_node_trace(struct kmem_cache *s,
 403                               gfp_t gfpflags,
 404                               int node, size_t size)
 405 {
 406         return kmem_cache_alloc_trace(s, gfpflags, size);
 407 }
 408 #endif /* CONFIG_NUMA */
 409
 410 #else /* CONFIG_TRACING */
 411 static __always_inline void *kmem_cache_alloc_trace(struct kmem_cache *s,
 412                 gfp_t flags, size_t size)
 413 {
 414         void *ret = kmem_cache_alloc(s, flags);
 415
 416         kasan_kmalloc(s, ret, size, flags);
 417         return ret;
 418 }
 419
 420 static __always_inline void *
 421 kmem_cache_alloc_node_trace(struct kmem_cache *s,
 422                               gfp_t gfpflags,
 423                               int node, size_t size)
 424 {
 425         void *ret = kmem_cache_alloc_node(s, gfpflags, node);
 426
 427         kasan_kmalloc(s, ret, size, gfpflags);
 428         return ret;
 429 }
 430 #endif /* CONFIG_TRACING */
 431
 432 extern void *kmalloc_order(size_t size, gfp_t flags, unsigned int order) __assume_page_alignment __malloc;
 433
 434 #ifdef CONFIG_TRACING
 435 extern void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order) __assume_page_alignment __malloc;
 436 #else
 437 static __always_inline void *
 438 kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
 439 {
 440         return kmalloc_order(size, flags, order);
 441 }
 442 #endif
 443
 444 static __always_inline void *kmalloc_large(size_t size, gfp_t flags)
 445 {
 446         unsigned int order = get_order(size);
 447         return kmalloc_order_trace(size, flags, order);
 448 }
 449
 450 /**
 451  * kmalloc - allocate memory
 452  * @size: how many bytes of memory are required.
 453  * @flags: the type of memory to allocate.
 454  *
 455  * kmalloc is the normal method of allocating memory
 456  * for objects smaller than page size in the kernel.
 457  *
 458  * The @flags argument may be one of:
 459  *
 460  * %GFP_USER - Allocate memory on behalf of user.  May sleep.
 461  *
 462  * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
 463  *
 464  * %GFP_ATOMIC - Allocation will not sleep.  May use emergency pools.
 465  *   For example, use this inside interrupt handlers.
 466  *
 467  * %GFP_HIGHUSER - Allocate pages from high memory.
 468  *
 469  * %GFP_NOIO - Do not do any I/O at all while trying to get memory.
 470  *
 471  * %GFP_NOFS - Do not make any fs calls while trying to get memory.
 472  *
 473  * %GFP_NOWAIT - Allocation will not sleep.
 474  *
 475  * %__GFP_THISNODE - Allocate node-local memory only.
 476  *
 477  * %GFP_DMA - Allocation suitable for DMA.
 478  *   Should only be used for kmalloc() caches. Otherwise, use a
 479  *   slab created with SLAB_DMA.
 480  *
 481  * Also it is possible to set different flags by OR'ing
 482  * in one or more of the following additional @flags:
 483  *
 484  * %__GFP_HIGH - This allocation has high priority and may use emergency pools.
 485  *
 486  * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
 487  *   (think twice before using).
 488  *
 489  * %__GFP_NORETRY - If memory is not immediately available,
 490  *   then give up at once.
 491  *
 492  * %__GFP_NOWARN - If allocation fails, don't issue any warnings.
 493  *
 494  * %__GFP_RETRY_MAYFAIL - Try really hard to succeed the allocation but fail
 495  *   eventually.
 496  *
 497  * There are other flags available as well, but these are not intended
 498  * for general use, and so are not documented here. For a full list of
 499  * potential flags, always refer to linux/gfp.h.
 500  */
 501 static __always_inline void *kmalloc(size_t size, gfp_t flags)
 502 {
 503         if (__builtin_constant_p(size)) {
 504                 if (size > KMALLOC_MAX_CACHE_SIZE)
 505                         return kmalloc_large(size, flags);
 506 #ifndef CONFIG_SLOB
 507                 if (!(flags & GFP_DMA)) {
 508                         unsigned int index = kmalloc_index(size);
 509
 510                         if (!index)
 511                                 return ZERO_SIZE_PTR;
 512
 513                         return kmem_cache_alloc_trace(kmalloc_caches[index],
 514                                         flags, size);
 515                 }
 516 #endif
 517         }
 518         return __kmalloc(size, flags);
 519 }
 520
 521 /*
 522  * Determine size used for the nth kmalloc cache.
 523  * return size or 0 if a kmalloc cache for that
 524  * size does not exist
 525  */
 526 static __always_inline unsigned int kmalloc_size(unsigned int n)
 527 {
 528 #ifndef CONFIG_SLOB
 529         if (n > 2)
 530                 return 1U << n;
 531
 532         if (n == 1 && KMALLOC_MIN_SIZE <= 32)
 533                 return 96;
 534
 535         if (n == 2 && KMALLOC_MIN_SIZE <= 64)
 536                 return 192;
 537 #endif
 538         return 0;
 539 }
 540
 541 static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
 542 {
 543 #ifndef CONFIG_SLOB
 544         if (__builtin_constant_p(size) &&
 545                 size <= KMALLOC_MAX_CACHE_SIZE && !(flags & GFP_DMA)) {
 546                 unsigned int i = kmalloc_index(size);
 547
 548                 if (!i)
 549                         return ZERO_SIZE_PTR;
 550
 551                 return kmem_cache_alloc_node_trace(kmalloc_caches[i],
 552                                                 flags, node, size);
 553         }
 554 #endif
 555         return __kmalloc_node(size, flags, node);
 556 }
 557
 558 struct memcg_cache_array {
 559         struct rcu_head rcu;
 560         struct kmem_cache *entries[0];
 561 };
 562
 563 /*
 564  * This is the main placeholder for memcg-related information in kmem caches.
 565  * Both the root cache and the child caches will have it. For the root cache,
 566  * this will hold a dynamically allocated array large enough to hold
 567  * information about the currently limited memcgs in the system. To allow the
 568  * array to be accessed without taking any locks, on relocation we free the old
 569  * version only after a grace period.
 570  *
 571  * Root and child caches hold different metadata.
 572  *
 573  * @root_cache: Common to root and child caches.  NULL for root, pointer to
 574  *              the root cache for children.
 575  *
 576  * The following fields are specific to root caches.
 577  *
 578  * @memcg_caches: kmemcg ID indexed table of child caches.  This table is
 579  *              used to index child cachces during allocation and cleared
 580  *              early during shutdown.
 581  *
 582  * @root_caches_node: List node for slab_root_caches list.
 583  *
 584  * @children:   List of all child caches.  While the child caches are also
 585  *              reachable through @memcg_caches, a child cache remains on
 586  *              this list until it is actually destroyed.
 587  *
 588  * The following fields are specific to child caches.
 589  *
 590  * @memcg:      Pointer to the memcg this cache belongs to.
 591  *
 592  * @children_node: List node for @root_cache->children list.
 593  *
 594  * @kmem_caches_node: List node for @memcg->kmem_caches list.
 595  */
 596 struct memcg_cache_params {
 597         struct kmem_cache *root_cache;
 598         union {
 599                 struct {
 600                         struct memcg_cache_array __rcu *memcg_caches;
 601                         struct list_head __root_caches_node;
 602                         struct list_head children;
 603                         bool dying;
 604                 };
 605                 struct {
 606                         struct mem_cgroup *memcg;
 607                         struct list_head children_node;
 608                         struct list_head kmem_caches_node;
 609
 610                         void (*deact_fn)(struct kmem_cache *);
 611                         union {
 612                                 struct rcu_head deact_rcu_head;
 613                                 struct work_struct deact_work;
 614                         };
 615                 };
 616         };
 617 };
 618
 619 int memcg_update_all_caches(int num_memcgs);
 620
 621 /**
 622  * kmalloc_array - allocate memory for an array.
 623  * @n: number of elements.
 624  * @size: element size.
 625  * @flags: the type of memory to allocate (see kmalloc).
 626  */
 627 static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
 628 {
 629         size_t bytes;
 630
 631         if (unlikely(check_mul_overflow(n, size, &bytes)))
 632                 return NULL;
 633         if (__builtin_constant_p(n) && __builtin_constant_p(size))
 634                 return kmalloc(bytes, flags);
 635         return __kmalloc(bytes, flags);
 636 }
 637
 638 /**
 639  * kcalloc - allocate memory for an array. The memory is set to zero.
 640  * @n: number of elements.
 641  * @size: element size.
 642  * @flags: the type of memory to allocate (see kmalloc).
 643  */
 644 static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
 645 {
 646         return kmalloc_array(n, size, flags | __GFP_ZERO);
 647 }
 648
 649 /*
 650  * kmalloc_track_caller is a special version of kmalloc that records the
 651  * calling function of the routine calling it for slab leak tracking instead
 652  * of just the calling function (confusing, eh?).
 653  * It's useful when the call to kmalloc comes from a widely-used standard
 654  * allocator where we care about the real place the memory allocation
 655  * request comes from.
 656  */
 657 extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
 658 #define kmalloc_track_caller(size, flags) \
 659         __kmalloc_track_caller(size, flags, _RET_IP_)
 660
 661 static inline void *kmalloc_array_node(size_t n, size_t size, gfp_t flags,
 662                                        int node)
 663 {
 664         size_t bytes;
 665
 666         if (unlikely(check_mul_overflow(n, size, &bytes)))
 667                 return NULL;
 668         if (__builtin_constant_p(n) && __builtin_constant_p(size))
 669                 return kmalloc_node(bytes, flags, node);
 670         return __kmalloc_node(bytes, flags, node);
 671 }
 672
 673 static inline void *kcalloc_node(size_t n, size_t size, gfp_t flags, int node)
 674 {
 675         return kmalloc_array_node(n, size, flags | __GFP_ZERO, node);
 676 }
 677
 678
 679 #ifdef CONFIG_NUMA
 680 extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
 681 #define kmalloc_node_track_caller(size, flags, node) \
 682         __kmalloc_node_track_caller(size, flags, node, \
 683                         _RET_IP_)
 684
 685 #else /* CONFIG_NUMA */
 686
 687 #define kmalloc_node_track_caller(size, flags, node) \
 688         kmalloc_track_caller(size, flags)
 689
 690 #endif /* CONFIG_NUMA */
 691
 692 /*
 693  * Shortcuts
 694  */
 695 static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
 696 {
 697         return kmem_cache_alloc(k, flags | __GFP_ZERO);
 698 }
 699
 700 /**
 701  * kzalloc - allocate memory. The memory is set to zero.
 702  * @size: how many bytes of memory are required.
 703  * @flags: the type of memory to allocate (see kmalloc).
 704  */
 705 static inline void *kzalloc(size_t size, gfp_t flags)
 706 {
 707         return kmalloc(size, flags | __GFP_ZERO);
 708 }
 709
 710 /**
 711  * kzalloc_node - allocate zeroed memory from a particular memory node.
 712  * @size: how many bytes of memory are required.
 713  * @flags: the type of memory to allocate (see kmalloc).
 714  * @node: memory node from which to allocate
 715  */
 716 static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
 717 {
 718         return kmalloc_node(size, flags | __GFP_ZERO, node);
 719 }
 720
 721 unsigned int kmem_cache_size(struct kmem_cache *s);
 722 void __init kmem_cache_init_late(void);
 723
 724 #if defined(CONFIG_SMP) && defined(CONFIG_SLAB)
 725 int slab_prepare_cpu(unsigned int cpu);
 726 int slab_dead_cpu(unsigned int cpu);
 727 #else
 728 #define slab_prepare_cpu        NULL
 729 #define slab_dead_cpu           NULL
 730 #endif
 731
 732 #endif  /* _LINUX_SLAB_H */