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