mm/slab_common.c

   1 /*
   2  * Slab allocator functions that are independent of the allocator strategy
   3  *
   4  * (C) 2012 Christoph Lameter <cl@linux.com>
   5  */
   6 #include <linux/slab.h>
   7
   8 #include <linux/mm.h>
   9 #include <linux/poison.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/memory.h>
  12 #include <linux/compiler.h>
  13 #include <linux/module.h>
  14 #include <linux/cpu.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/seq_file.h>
  17 #include <linux/proc_fs.h>
  18 #include <asm/cacheflush.h>
  19 #include <asm/tlbflush.h>
  20 #include <asm/page.h>
  21 #include <linux/memcontrol.h>
  22 #include <trace/events/kmem.h>
  23
  24 #include "slab.h"
  25
  26 enum slab_state slab_state;
  27 LIST_HEAD(slab_caches);
  28 DEFINE_MUTEX(slab_mutex);
  29 struct kmem_cache *kmem_cache;
  30
  31 #ifdef CONFIG_DEBUG_VM
  32 static int kmem_cache_sanity_check(const char *name, size_t size)
  33 {
  34         struct kmem_cache *s = NULL;
  35
  36         if (!name || in_interrupt() || size < sizeof(void *) ||
  37                 size > KMALLOC_MAX_SIZE) {
  38                 pr_err("kmem_cache_create(%s) integrity check failed\n", name);
  39                 return -EINVAL;
  40         }
  41
  42         list_for_each_entry(s, &slab_caches, list) {
  43                 char tmp;
  44                 int res;
  45
  46                 /*
  47                  * This happens when the module gets unloaded and doesn't
  48                  * destroy its slab cache and no-one else reuses the vmalloc
  49                  * area of the module.  Print a warning.
  50                  */
  51                 res = probe_kernel_address(s->name, tmp);
  52                 if (res) {
  53                         pr_err("Slab cache with size %d has lost its name\n",
  54                                s->object_size);
  55                         continue;
  56                 }
  57
  58 #if !defined(CONFIG_SLUB) || !defined(CONFIG_SLUB_DEBUG_ON)
  59                 if (!strcmp(s->name, name)) {
  60                         pr_err("%s (%s): Cache name already exists.\n",
  61                                __func__, name);
  62                         dump_stack();
  63                         s = NULL;
  64                         return -EINVAL;
  65                 }
  66 #endif
  67         }
  68
  69         WARN_ON(strchr(name, ' '));     /* It confuses parsers */
  70         return 0;
  71 }
  72 #else
  73 static inline int kmem_cache_sanity_check(const char *name, size_t size)
  74 {
  75         return 0;
  76 }
  77 #endif
  78
  79 #ifdef CONFIG_MEMCG_KMEM
  80 int memcg_update_all_caches(int num_memcgs)
  81 {
  82         struct kmem_cache *s;
  83         int ret = 0;
  84         mutex_lock(&slab_mutex);
  85
  86         list_for_each_entry(s, &slab_caches, list) {
  87                 if (!is_root_cache(s))
  88                         continue;
  89
  90                 ret = memcg_update_cache_size(s, num_memcgs);
  91                 /*
  92                  * See comment in memcontrol.c, memcg_update_cache_size:
  93                  * Instead of freeing the memory, we'll just leave the caches
  94                  * up to this point in an updated state.
  95                  */
  96                 if (ret)
  97                         goto out;
  98         }
  99
 100         memcg_update_array_size(num_memcgs);
 101 out:
 102         mutex_unlock(&slab_mutex);
 103         return ret;
 104 }
 105 #endif
 106
 107 /*
 108  * Figure out what the alignment of the objects will be given a set of
 109  * flags, a user specified alignment and the size of the objects.
 110  */
 111 unsigned long calculate_alignment(unsigned long flags,
 112                 unsigned long align, unsigned long size)
 113 {
 114         /*
 115          * If the user wants hardware cache aligned objects then follow that
 116          * suggestion if the object is sufficiently large.
 117          *
 118          * The hardware cache alignment cannot override the specified
 119          * alignment though. If that is greater then use it.
 120          */
 121         if (flags & SLAB_HWCACHE_ALIGN) {
 122                 unsigned long ralign = cache_line_size();
 123                 while (size <= ralign / 2)
 124                         ralign /= 2;
 125                 align = max(align, ralign);
 126         }
 127
 128         if (align < ARCH_SLAB_MINALIGN)
 129                 align = ARCH_SLAB_MINALIGN;
 130
 131         return ALIGN(align, sizeof(void *));
 132 }
 133
 134 static struct kmem_cache *
 135 do_kmem_cache_create(char *name, size_t object_size, size_t size, size_t align,
 136                      unsigned long flags, void (*ctor)(void *),
 137                      struct mem_cgroup *memcg, struct kmem_cache *root_cache)
 138 {
 139         struct kmem_cache *s;
 140         int err;
 141
 142         err = -ENOMEM;
 143         s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
 144         if (!s)
 145                 goto out;
 146
 147         s->name = name;
 148         s->object_size = object_size;
 149         s->size = size;
 150         s->align = align;
 151         s->ctor = ctor;
 152
 153         err = memcg_alloc_cache_params(memcg, s, root_cache);
 154         if (err)
 155                 goto out_free_cache;
 156
 157         err = __kmem_cache_create(s, flags);
 158         if (err)
 159                 goto out_free_cache;
 160
 161         s->refcount = 1;
 162         list_add(&s->list, &slab_caches);
 163         memcg_register_cache(s);
 164 out:
 165         if (err)
 166                 return ERR_PTR(err);
 167         return s;
 168
 169 out_free_cache:
 170         memcg_free_cache_params(s);
 171         kfree(s);
 172         goto out;
 173 }
 174
 175 /*
 176  * kmem_cache_create - Create a cache.
 177  * @name: A string which is used in /proc/slabinfo to identify this cache.
 178  * @size: The size of objects to be created in this cache.
 179  * @align: The required alignment for the objects.
 180  * @flags: SLAB flags
 181  * @ctor: A constructor for the objects.
 182  *
 183  * Returns a ptr to the cache on success, NULL on failure.
 184  * Cannot be called within a interrupt, but can be interrupted.
 185  * The @ctor is run when new pages are allocated by the cache.
 186  *
 187  * The flags are
 188  *
 189  * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
 190  * to catch references to uninitialised memory.
 191  *
 192  * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
 193  * for buffer overruns.
 194  *
 195  * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
 196  * cacheline.  This can be beneficial if you're counting cycles as closely
 197  * as davem.
 198  */
 199 struct kmem_cache *
 200 kmem_cache_create(const char *name, size_t size, size_t align,
 201                   unsigned long flags, void (*ctor)(void *))
 202 {
 203         struct kmem_cache *s;
 204         char *cache_name;
 205         int err;
 206
 207         get_online_cpus();
 208         mutex_lock(&slab_mutex);
 209
 210         err = kmem_cache_sanity_check(name, size);
 211         if (err)
 212                 goto out_unlock;
 213
 214         /*
 215          * Some allocators will constraint the set of valid flags to a subset
 216          * of all flags. We expect them to define CACHE_CREATE_MASK in this
 217          * case, and we'll just provide them with a sanitized version of the
 218          * passed flags.
 219          */
 220         flags &= CACHE_CREATE_MASK;
 221
 222         s = __kmem_cache_alias(name, size, align, flags, ctor);
 223         if (s)
 224                 goto out_unlock;
 225
 226         cache_name = kstrdup(name, GFP_KERNEL);
 227         if (!cache_name) {
 228                 err = -ENOMEM;
 229                 goto out_unlock;
 230         }
 231
 232         s = do_kmem_cache_create(cache_name, size, size,
 233                                  calculate_alignment(flags, align, size),
 234                                  flags, ctor, NULL, NULL);
 235         if (IS_ERR(s)) {
 236                 err = PTR_ERR(s);
 237                 kfree(cache_name);
 238         }
 239
 240 out_unlock:
 241         mutex_unlock(&slab_mutex);
 242         put_online_cpus();
 243
 244         if (err) {
 245                 if (flags & SLAB_PANIC)
 246                         panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
 247                                 name, err);
 248                 else {
 249                         printk(KERN_WARNING "kmem_cache_create(%s) failed with error %d",
 250                                 name, err);
 251                         dump_stack();
 252                 }
 253                 return NULL;
 254         }
 255         return s;
 256 }
 257 EXPORT_SYMBOL(kmem_cache_create);
 258
 259 #ifdef CONFIG_MEMCG_KMEM
 260 /*
 261  * kmem_cache_create_memcg - Create a cache for a memory cgroup.
 262  * @memcg: The memory cgroup the new cache is for.
 263  * @root_cache: The parent of the new cache.
 264  *
 265  * This function attempts to create a kmem cache that will serve allocation
 266  * requests going from @memcg to @root_cache. The new cache inherits properties
 267  * from its parent.
 268  */
 269 void kmem_cache_create_memcg(struct mem_cgroup *memcg, struct kmem_cache *root_cache)
 270 {
 271         struct kmem_cache *s;
 272         char *cache_name;
 273
 274         get_online_cpus();
 275         mutex_lock(&slab_mutex);
 276
 277         /*
 278          * Since per-memcg caches are created asynchronously on first
 279          * allocation (see memcg_kmem_get_cache()), several threads can try to
 280          * create the same cache, but only one of them may succeed.
 281          */
 282         if (cache_from_memcg_idx(root_cache, memcg_cache_id(memcg)))
 283                 goto out_unlock;
 284
 285         cache_name = memcg_create_cache_name(memcg, root_cache);
 286         if (!cache_name)
 287                 goto out_unlock;
 288
 289         s = do_kmem_cache_create(cache_name, root_cache->object_size,
 290                                  root_cache->size, root_cache->align,
 291                                  root_cache->flags, root_cache->ctor,
 292                                  memcg, root_cache);
 293         if (IS_ERR(s)) {
 294                 kfree(cache_name);
 295                 goto out_unlock;
 296         }
 297
 298         s->allocflags |= __GFP_KMEMCG;
 299
 300 out_unlock:
 301         mutex_unlock(&slab_mutex);
 302         put_online_cpus();
 303 }
 304
 305 static int kmem_cache_destroy_memcg_children(struct kmem_cache *s)
 306 {
 307         int rc;
 308
 309         if (!s->memcg_params ||
 310             !s->memcg_params->is_root_cache)
 311                 return 0;
 312
 313         mutex_unlock(&slab_mutex);
 314         rc = __kmem_cache_destroy_memcg_children(s);
 315         mutex_lock(&slab_mutex);
 316
 317         return rc;
 318 }
 319 #else
 320 static int kmem_cache_destroy_memcg_children(struct kmem_cache *s)
 321 {
 322         return 0;
 323 }
 324 #endif /* CONFIG_MEMCG_KMEM */
 325
 326 void kmem_cache_destroy(struct kmem_cache *s)
 327 {
 328         get_online_cpus();
 329         mutex_lock(&slab_mutex);
 330
 331         s->refcount--;
 332         if (s->refcount)
 333                 goto out_unlock;
 334
 335         if (kmem_cache_destroy_memcg_children(s) != 0)
 336                 goto out_unlock;
 337
 338         list_del(&s->list);
 339         memcg_unregister_cache(s);
 340
 341         if (__kmem_cache_shutdown(s) != 0) {
 342                 list_add(&s->list, &slab_caches);
 343                 memcg_register_cache(s);
 344                 printk(KERN_ERR "kmem_cache_destroy %s: "
 345                        "Slab cache still has objects\n", s->name);
 346                 dump_stack();
 347                 goto out_unlock;
 348         }
 349
 350         mutex_unlock(&slab_mutex);
 351         if (s->flags & SLAB_DESTROY_BY_RCU)
 352                 rcu_barrier();
 353
 354         memcg_free_cache_params(s);
 355         kfree(s->name);
 356         kmem_cache_free(kmem_cache, s);
 357         goto out_put_cpus;
 358
 359 out_unlock:
 360         mutex_unlock(&slab_mutex);
 361 out_put_cpus:
 362         put_online_cpus();
 363 }
 364 EXPORT_SYMBOL(kmem_cache_destroy);
 365
 366 int slab_is_available(void)
 367 {
 368         return slab_state >= UP;
 369 }
 370
 371 #ifndef CONFIG_SLOB
 372 /* Create a cache during boot when no slab services are available yet */
 373 void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size,
 374                 unsigned long flags)
 375 {
 376         int err;
 377
 378         s->name = name;
 379         s->size = s->object_size = size;
 380         s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size);
 381         err = __kmem_cache_create(s, flags);
 382
 383         if (err)
 384                 panic("Creation of kmalloc slab %s size=%zu failed. Reason %d\n",
 385                                         name, size, err);
 386
 387         s->refcount = -1;       /* Exempt from merging for now */
 388 }
 389
 390 struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size,
 391                                 unsigned long flags)
 392 {
 393         struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
 394
 395         if (!s)
 396                 panic("Out of memory when creating slab %s\n", name);
 397
 398         create_boot_cache(s, name, size, flags);
 399         list_add(&s->list, &slab_caches);
 400         s->refcount = 1;
 401         return s;
 402 }
 403
 404 struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
 405 EXPORT_SYMBOL(kmalloc_caches);
 406
 407 #ifdef CONFIG_ZONE_DMA
 408 struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
 409 EXPORT_SYMBOL(kmalloc_dma_caches);
 410 #endif
 411
 412 /*
 413  * Conversion table for small slabs sizes / 8 to the index in the
 414  * kmalloc array. This is necessary for slabs < 192 since we have non power
 415  * of two cache sizes there. The size of larger slabs can be determined using
 416  * fls.
 417  */
 418 static s8 size_index[24] = {
 419         3,      /* 8 */
 420         4,      /* 16 */
 421         5,      /* 24 */
 422         5,      /* 32 */
 423         6,      /* 40 */
 424         6,      /* 48 */
 425         6,      /* 56 */
 426         6,      /* 64 */
 427         1,      /* 72 */
 428         1,      /* 80 */
 429         1,      /* 88 */
 430         1,      /* 96 */
 431         7,      /* 104 */
 432         7,      /* 112 */
 433         7,      /* 120 */
 434         7,      /* 128 */
 435         2,      /* 136 */
 436         2,      /* 144 */
 437         2,      /* 152 */
 438         2,      /* 160 */
 439         2,      /* 168 */
 440         2,      /* 176 */
 441         2,      /* 184 */
 442         2       /* 192 */
 443 };
 444
 445 static inline int size_index_elem(size_t bytes)
 446 {
 447         return (bytes - 1) / 8;
 448 }
 449
 450 /*
 451  * Find the kmem_cache structure that serves a given size of
 452  * allocation
 453  */
 454 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
 455 {
 456         int index;
 457
 458         if (unlikely(size > KMALLOC_MAX_SIZE)) {
 459                 WARN_ON_ONCE(!(flags & __GFP_NOWARN));
 460                 return NULL;
 461         }
 462
 463         if (size <= 192) {
 464                 if (!size)
 465                         return ZERO_SIZE_PTR;
 466
 467                 index = size_index[size_index_elem(size)];
 468         } else
 469                 index = fls(size - 1);
 470
 471 #ifdef CONFIG_ZONE_DMA
 472         if (unlikely((flags & GFP_DMA)))
 473                 return kmalloc_dma_caches[index];
 474
 475 #endif
 476         return kmalloc_caches[index];
 477 }
 478
 479 /*
 480  * Create the kmalloc array. Some of the regular kmalloc arrays
 481  * may already have been created because they were needed to
 482  * enable allocations for slab creation.
 483  */
 484 void __init create_kmalloc_caches(unsigned long flags)
 485 {
 486         int i;
 487
 488         /*
 489          * Patch up the size_index table if we have strange large alignment
 490          * requirements for the kmalloc array. This is only the case for
 491          * MIPS it seems. The standard arches will not generate any code here.
 492          *
 493          * Largest permitted alignment is 256 bytes due to the way we
 494          * handle the index determination for the smaller caches.
 495          *
 496          * Make sure that nothing crazy happens if someone starts tinkering
 497          * around with ARCH_KMALLOC_MINALIGN
 498          */
 499         BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
 500                 (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
 501
 502         for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
 503                 int elem = size_index_elem(i);
 504
 505                 if (elem >= ARRAY_SIZE(size_index))
 506                         break;
 507                 size_index[elem] = KMALLOC_SHIFT_LOW;
 508         }
 509
 510         if (KMALLOC_MIN_SIZE >= 64) {
 511                 /*
 512                  * The 96 byte size cache is not used if the alignment
 513                  * is 64 byte.
 514                  */
 515                 for (i = 64 + 8; i <= 96; i += 8)
 516                         size_index[size_index_elem(i)] = 7;
 517
 518         }
 519
 520         if (KMALLOC_MIN_SIZE >= 128) {
 521                 /*
 522                  * The 192 byte sized cache is not used if the alignment
 523                  * is 128 byte. Redirect kmalloc to use the 256 byte cache
 524                  * instead.
 525                  */
 526                 for (i = 128 + 8; i <= 192; i += 8)
 527                         size_index[size_index_elem(i)] = 8;
 528         }
 529         for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
 530                 if (!kmalloc_caches[i]) {
 531                         kmalloc_caches[i] = create_kmalloc_cache(NULL,
 532                                                         1 << i, flags);
 533                 }
 534
 535                 /*
 536                  * Caches that are not of the two-to-the-power-of size.
 537                  * These have to be created immediately after the
 538                  * earlier power of two caches
 539                  */
 540                 if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6)
 541                         kmalloc_caches[1] = create_kmalloc_cache(NULL, 96, flags);
 542
 543                 if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7)
 544                         kmalloc_caches[2] = create_kmalloc_cache(NULL, 192, flags);
 545         }
 546
 547         /* Kmalloc array is now usable */
 548         slab_state = UP;
 549
 550         for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
 551                 struct kmem_cache *s = kmalloc_caches[i];
 552                 char *n;
 553
 554                 if (s) {
 555                         n = kasprintf(GFP_NOWAIT, "kmalloc-%d", kmalloc_size(i));
 556
 557                         BUG_ON(!n);
 558                         s->name = n;
 559                 }
 560         }
 561
 562 #ifdef CONFIG_ZONE_DMA
 563         for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
 564                 struct kmem_cache *s = kmalloc_caches[i];
 565
 566                 if (s) {
 567                         int size = kmalloc_size(i);
 568                         char *n = kasprintf(GFP_NOWAIT,
 569                                  "dma-kmalloc-%d", size);
 570
 571                         BUG_ON(!n);
 572                         kmalloc_dma_caches[i] = create_kmalloc_cache(n,
 573                                 size, SLAB_CACHE_DMA | flags);
 574                 }
 575         }
 576 #endif
 577 }
 578 #endif /* !CONFIG_SLOB */
 579
 580 #ifdef CONFIG_TRACING
 581 void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
 582 {
 583         void *ret = kmalloc_order(size, flags, order);
 584         trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags);
 585         return ret;
 586 }
 587 EXPORT_SYMBOL(kmalloc_order_trace);
 588 #endif
 589
 590 #ifdef CONFIG_SLABINFO
 591
 592 #ifdef CONFIG_SLAB
 593 #define SLABINFO_RIGHTS (S_IWUSR | S_IRUSR)
 594 #else
 595 #define SLABINFO_RIGHTS S_IRUSR
 596 #endif
 597
 598 void print_slabinfo_header(struct seq_file *m)
 599 {
 600         /*
 601          * Output format version, so at least we can change it
 602          * without _too_ many complaints.
 603          */
 604 #ifdef CONFIG_DEBUG_SLAB
 605         seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
 606 #else
 607         seq_puts(m, "slabinfo - version: 2.1\n");
 608 #endif
 609         seq_puts(m, "# name            <active_objs> <num_objs> <objsize> "
 610                  "<objperslab> <pagesperslab>");
 611         seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
 612         seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
 613 #ifdef CONFIG_DEBUG_SLAB
 614         seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
 615                  "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
 616         seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
 617 #endif
 618         seq_putc(m, '\n');
 619 }
 620
 621 static void *s_start(struct seq_file *m, loff_t *pos)
 622 {
 623         loff_t n = *pos;
 624
 625         mutex_lock(&slab_mutex);
 626         if (!n)
 627                 print_slabinfo_header(m);
 628
 629         return seq_list_start(&slab_caches, *pos);
 630 }
 631
 632 void *slab_next(struct seq_file *m, void *p, loff_t *pos)
 633 {
 634         return seq_list_next(p, &slab_caches, pos);
 635 }
 636
 637 void slab_stop(struct seq_file *m, void *p)
 638 {
 639         mutex_unlock(&slab_mutex);
 640 }
 641
 642 static void
 643 memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
 644 {
 645         struct kmem_cache *c;
 646         struct slabinfo sinfo;
 647         int i;
 648
 649         if (!is_root_cache(s))
 650                 return;
 651
 652         for_each_memcg_cache_index(i) {
 653                 c = cache_from_memcg_idx(s, i);
 654                 if (!c)
 655                         continue;
 656
 657                 memset(&sinfo, 0, sizeof(sinfo));
 658                 get_slabinfo(c, &sinfo);
 659
 660                 info->active_slabs += sinfo.active_slabs;
 661                 info->num_slabs += sinfo.num_slabs;
 662                 info->shared_avail += sinfo.shared_avail;
 663                 info->active_objs += sinfo.active_objs;
 664                 info->num_objs += sinfo.num_objs;
 665         }
 666 }
 667
 668 int cache_show(struct kmem_cache *s, struct seq_file *m)
 669 {
 670         struct slabinfo sinfo;
 671
 672         memset(&sinfo, 0, sizeof(sinfo));
 673         get_slabinfo(s, &sinfo);
 674
 675         memcg_accumulate_slabinfo(s, &sinfo);
 676
 677         seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
 678                    cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size,
 679                    sinfo.objects_per_slab, (1 << sinfo.cache_order));
 680
 681         seq_printf(m, " : tunables %4u %4u %4u",
 682                    sinfo.limit, sinfo.batchcount, sinfo.shared);
 683         seq_printf(m, " : slabdata %6lu %6lu %6lu",
 684                    sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
 685         slabinfo_show_stats(m, s);
 686         seq_putc(m, '\n');
 687         return 0;
 688 }
 689
 690 static int s_show(struct seq_file *m, void *p)
 691 {
 692         struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
 693
 694         if (!is_root_cache(s))
 695                 return 0;
 696         return cache_show(s, m);
 697 }
 698
 699 /*
 700  * slabinfo_op - iterator that generates /proc/slabinfo
 701  *
 702  * Output layout:
 703  * cache-name
 704  * num-active-objs
 705  * total-objs
 706  * object size
 707  * num-active-slabs
 708  * total-slabs
 709  * num-pages-per-slab
 710  * + further values on SMP and with statistics enabled
 711  */
 712 static const struct seq_operations slabinfo_op = {
 713         .start = s_start,
 714         .next = slab_next,
 715         .stop = slab_stop,
 716         .show = s_show,
 717 };
 718
 719 static int slabinfo_open(struct inode *inode, struct file *file)
 720 {
 721         return seq_open(file, &slabinfo_op);
 722 }
 723
 724 static const struct file_operations proc_slabinfo_operations = {
 725         .open           = slabinfo_open,
 726         .read           = seq_read,
 727         .write          = slabinfo_write,
 728         .llseek         = seq_lseek,
 729         .release        = seq_release,
 730 };
 731
 732 static int __init slab_proc_init(void)
 733 {
 734         proc_create("slabinfo", SLABINFO_RIGHTS, NULL,
 735                                                 &proc_slabinfo_operations);
 736         return 0;
 737 }
 738 module_init(slab_proc_init);
 739 #endif /* CONFIG_SLABINFO */