linux/mm/slab_common.c
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   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#define CREATE_TRACE_POINTS
  24#include <trace/events/kmem.h>
  25
  26#include "slab.h"
  27
  28enum slab_state slab_state;
  29LIST_HEAD(slab_caches);
  30DEFINE_MUTEX(slab_mutex);
  31struct kmem_cache *kmem_cache;
  32
  33/*
  34 * Set of flags that will prevent slab merging
  35 */
  36#define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
  37                SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \
  38                SLAB_FAILSLAB | SLAB_KASAN)
  39
  40#define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
  41                         SLAB_NOTRACK | SLAB_ACCOUNT)
  42
  43/*
  44 * Merge control. If this is set then no merging of slab caches will occur.
  45 * (Could be removed. This was introduced to pacify the merge skeptics.)
  46 */
  47static int slab_nomerge;
  48
  49static int __init setup_slab_nomerge(char *str)
  50{
  51        slab_nomerge = 1;
  52        return 1;
  53}
  54
  55#ifdef CONFIG_SLUB
  56__setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
  57#endif
  58
  59__setup("slab_nomerge", setup_slab_nomerge);
  60
  61/*
  62 * Determine the size of a slab object
  63 */
  64unsigned int kmem_cache_size(struct kmem_cache *s)
  65{
  66        return s->object_size;
  67}
  68EXPORT_SYMBOL(kmem_cache_size);
  69
  70#ifdef CONFIG_DEBUG_VM
  71static int kmem_cache_sanity_check(const char *name, size_t size)
  72{
  73        struct kmem_cache *s = NULL;
  74
  75        if (!name || in_interrupt() || size < sizeof(void *) ||
  76                size > KMALLOC_MAX_SIZE) {
  77                pr_err("kmem_cache_create(%s) integrity check failed\n", name);
  78                return -EINVAL;
  79        }
  80
  81        list_for_each_entry(s, &slab_caches, list) {
  82                char tmp;
  83                int res;
  84
  85                /*
  86                 * This happens when the module gets unloaded and doesn't
  87                 * destroy its slab cache and no-one else reuses the vmalloc
  88                 * area of the module.  Print a warning.
  89                 */
  90                res = probe_kernel_address(s->name, tmp);
  91                if (res) {
  92                        pr_err("Slab cache with size %d has lost its name\n",
  93                               s->object_size);
  94                        continue;
  95                }
  96        }
  97
  98        WARN_ON(strchr(name, ' '));     /* It confuses parsers */
  99        return 0;
 100}
 101#else
 102static inline int kmem_cache_sanity_check(const char *name, size_t size)
 103{
 104        return 0;
 105}
 106#endif
 107
 108void __kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p)
 109{
 110        size_t i;
 111
 112        for (i = 0; i < nr; i++) {
 113                if (s)
 114                        kmem_cache_free(s, p[i]);
 115                else
 116                        kfree(p[i]);
 117        }
 118}
 119
 120int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr,
 121                                                                void **p)
 122{
 123        size_t i;
 124
 125        for (i = 0; i < nr; i++) {
 126                void *x = p[i] = kmem_cache_alloc(s, flags);
 127                if (!x) {
 128                        __kmem_cache_free_bulk(s, i, p);
 129                        return 0;
 130                }
 131        }
 132        return i;
 133}
 134
 135#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
 136void slab_init_memcg_params(struct kmem_cache *s)
 137{
 138        s->memcg_params.is_root_cache = true;
 139        INIT_LIST_HEAD(&s->memcg_params.list);
 140        RCU_INIT_POINTER(s->memcg_params.memcg_caches, NULL);
 141}
 142
 143static int init_memcg_params(struct kmem_cache *s,
 144                struct mem_cgroup *memcg, struct kmem_cache *root_cache)
 145{
 146        struct memcg_cache_array *arr;
 147
 148        if (memcg) {
 149                s->memcg_params.is_root_cache = false;
 150                s->memcg_params.memcg = memcg;
 151                s->memcg_params.root_cache = root_cache;
 152                return 0;
 153        }
 154
 155        slab_init_memcg_params(s);
 156
 157        if (!memcg_nr_cache_ids)
 158                return 0;
 159
 160        arr = kzalloc(sizeof(struct memcg_cache_array) +
 161                      memcg_nr_cache_ids * sizeof(void *),
 162                      GFP_KERNEL);
 163        if (!arr)
 164                return -ENOMEM;
 165
 166        RCU_INIT_POINTER(s->memcg_params.memcg_caches, arr);
 167        return 0;
 168}
 169
 170static void destroy_memcg_params(struct kmem_cache *s)
 171{
 172        if (is_root_cache(s))
 173                kfree(rcu_access_pointer(s->memcg_params.memcg_caches));
 174}
 175
 176static int update_memcg_params(struct kmem_cache *s, int new_array_size)
 177{
 178        struct memcg_cache_array *old, *new;
 179
 180        if (!is_root_cache(s))
 181                return 0;
 182
 183        new = kzalloc(sizeof(struct memcg_cache_array) +
 184                      new_array_size * sizeof(void *), GFP_KERNEL);
 185        if (!new)
 186                return -ENOMEM;
 187
 188        old = rcu_dereference_protected(s->memcg_params.memcg_caches,
 189                                        lockdep_is_held(&slab_mutex));
 190        if (old)
 191                memcpy(new->entries, old->entries,
 192                       memcg_nr_cache_ids * sizeof(void *));
 193
 194        rcu_assign_pointer(s->memcg_params.memcg_caches, new);
 195        if (old)
 196                kfree_rcu(old, rcu);
 197        return 0;
 198}
 199
 200int memcg_update_all_caches(int num_memcgs)
 201{
 202        struct kmem_cache *s;
 203        int ret = 0;
 204
 205        mutex_lock(&slab_mutex);
 206        list_for_each_entry(s, &slab_caches, list) {
 207                ret = update_memcg_params(s, num_memcgs);
 208                /*
 209                 * Instead of freeing the memory, we'll just leave the caches
 210                 * up to this point in an updated state.
 211                 */
 212                if (ret)
 213                        break;
 214        }
 215        mutex_unlock(&slab_mutex);
 216        return ret;
 217}
 218#else
 219static inline int init_memcg_params(struct kmem_cache *s,
 220                struct mem_cgroup *memcg, struct kmem_cache *root_cache)
 221{
 222        return 0;
 223}
 224
 225static inline void destroy_memcg_params(struct kmem_cache *s)
 226{
 227}
 228#endif /* CONFIG_MEMCG && !CONFIG_SLOB */
 229
 230/*
 231 * Find a mergeable slab cache
 232 */
 233int slab_unmergeable(struct kmem_cache *s)
 234{
 235        if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
 236                return 1;
 237
 238        if (!is_root_cache(s))
 239                return 1;
 240
 241        if (s->ctor)
 242                return 1;
 243
 244        /*
 245         * We may have set a slab to be unmergeable during bootstrap.
 246         */
 247        if (s->refcount < 0)
 248                return 1;
 249
 250        return 0;
 251}
 252
 253struct kmem_cache *find_mergeable(size_t size, size_t align,
 254                unsigned long flags, const char *name, void (*ctor)(void *))
 255{
 256        struct kmem_cache *s;
 257
 258        if (slab_nomerge || (flags & SLAB_NEVER_MERGE))
 259                return NULL;
 260
 261        if (ctor)
 262                return NULL;
 263
 264        size = ALIGN(size, sizeof(void *));
 265        align = calculate_alignment(flags, align, size);
 266        size = ALIGN(size, align);
 267        flags = kmem_cache_flags(size, flags, name, NULL);
 268
 269        list_for_each_entry_reverse(s, &slab_caches, list) {
 270                if (slab_unmergeable(s))
 271                        continue;
 272
 273                if (size > s->size)
 274                        continue;
 275
 276                if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME))
 277                        continue;
 278                /*
 279                 * Check if alignment is compatible.
 280                 * Courtesy of Adrian Drzewiecki
 281                 */
 282                if ((s->size & ~(align - 1)) != s->size)
 283                        continue;
 284
 285                if (s->size - size >= sizeof(void *))
 286                        continue;
 287
 288                if (IS_ENABLED(CONFIG_SLAB) && align &&
 289                        (align > s->align || s->align % align))
 290                        continue;
 291
 292                return s;
 293        }
 294        return NULL;
 295}
 296
 297/*
 298 * Figure out what the alignment of the objects will be given a set of
 299 * flags, a user specified alignment and the size of the objects.
 300 */
 301unsigned long calculate_alignment(unsigned long flags,
 302                unsigned long align, unsigned long size)
 303{
 304        /*
 305         * If the user wants hardware cache aligned objects then follow that
 306         * suggestion if the object is sufficiently large.
 307         *
 308         * The hardware cache alignment cannot override the specified
 309         * alignment though. If that is greater then use it.
 310         */
 311        if (flags & SLAB_HWCACHE_ALIGN) {
 312                unsigned long ralign = cache_line_size();
 313                while (size <= ralign / 2)
 314                        ralign /= 2;
 315                align = max(align, ralign);
 316        }
 317
 318        if (align < ARCH_SLAB_MINALIGN)
 319                align = ARCH_SLAB_MINALIGN;
 320
 321        return ALIGN(align, sizeof(void *));
 322}
 323
 324static struct kmem_cache *create_cache(const char *name,
 325                size_t object_size, size_t size, size_t align,
 326                unsigned long flags, void (*ctor)(void *),
 327                struct mem_cgroup *memcg, struct kmem_cache *root_cache)
 328{
 329        struct kmem_cache *s;
 330        int err;
 331
 332        err = -ENOMEM;
 333        s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
 334        if (!s)
 335                goto out;
 336
 337        s->name = name;
 338        s->object_size = object_size;
 339        s->size = size;
 340        s->align = align;
 341        s->ctor = ctor;
 342
 343        err = init_memcg_params(s, memcg, root_cache);
 344        if (err)
 345                goto out_free_cache;
 346
 347        err = __kmem_cache_create(s, flags);
 348        if (err)
 349                goto out_free_cache;
 350
 351        s->refcount = 1;
 352        list_add(&s->list, &slab_caches);
 353out:
 354        if (err)
 355                return ERR_PTR(err);
 356        return s;
 357
 358out_free_cache:
 359        destroy_memcg_params(s);
 360        kmem_cache_free(kmem_cache, s);
 361        goto out;
 362}
 363
 364/*
 365 * kmem_cache_create - Create a cache.
 366 * @name: A string which is used in /proc/slabinfo to identify this cache.
 367 * @size: The size of objects to be created in this cache.
 368 * @align: The required alignment for the objects.
 369 * @flags: SLAB flags
 370 * @ctor: A constructor for the objects.
 371 *
 372 * Returns a ptr to the cache on success, NULL on failure.
 373 * Cannot be called within a interrupt, but can be interrupted.
 374 * The @ctor is run when new pages are allocated by the cache.
 375 *
 376 * The flags are
 377 *
 378 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
 379 * to catch references to uninitialised memory.
 380 *
 381 * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
 382 * for buffer overruns.
 383 *
 384 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
 385 * cacheline.  This can be beneficial if you're counting cycles as closely
 386 * as davem.
 387 */
 388struct kmem_cache *
 389kmem_cache_create(const char *name, size_t size, size_t align,
 390                  unsigned long flags, void (*ctor)(void *))
 391{
 392        struct kmem_cache *s = NULL;
 393        const char *cache_name;
 394        int err;
 395
 396        get_online_cpus();
 397        get_online_mems();
 398        memcg_get_cache_ids();
 399
 400        mutex_lock(&slab_mutex);
 401
 402        err = kmem_cache_sanity_check(name, size);
 403        if (err) {
 404                goto out_unlock;
 405        }
 406
 407        /*
 408         * Some allocators will constraint the set of valid flags to a subset
 409         * of all flags. We expect them to define CACHE_CREATE_MASK in this
 410         * case, and we'll just provide them with a sanitized version of the
 411         * passed flags.
 412         */
 413        flags &= CACHE_CREATE_MASK;
 414
 415        s = __kmem_cache_alias(name, size, align, flags, ctor);
 416        if (s)
 417                goto out_unlock;
 418
 419        cache_name = kstrdup_const(name, GFP_KERNEL);
 420        if (!cache_name) {
 421                err = -ENOMEM;
 422                goto out_unlock;
 423        }
 424
 425        s = create_cache(cache_name, size, size,
 426                         calculate_alignment(flags, align, size),
 427                         flags, ctor, NULL, NULL);
 428        if (IS_ERR(s)) {
 429                err = PTR_ERR(s);
 430                kfree_const(cache_name);
 431        }
 432
 433out_unlock:
 434        mutex_unlock(&slab_mutex);
 435
 436        memcg_put_cache_ids();
 437        put_online_mems();
 438        put_online_cpus();
 439
 440        if (err) {
 441                if (flags & SLAB_PANIC)
 442                        panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
 443                                name, err);
 444                else {
 445                        pr_warn("kmem_cache_create(%s) failed with error %d\n",
 446                                name, err);
 447                        dump_stack();
 448                }
 449                return NULL;
 450        }
 451        return s;
 452}
 453EXPORT_SYMBOL(kmem_cache_create);
 454
 455static int shutdown_cache(struct kmem_cache *s,
 456                struct list_head *release, bool *need_rcu_barrier)
 457{
 458        if (__kmem_cache_shutdown(s) != 0)
 459                return -EBUSY;
 460
 461        if (s->flags & SLAB_DESTROY_BY_RCU)
 462                *need_rcu_barrier = true;
 463
 464        list_move(&s->list, release);
 465        return 0;
 466}
 467
 468static void release_caches(struct list_head *release, bool need_rcu_barrier)
 469{
 470        struct kmem_cache *s, *s2;
 471
 472        if (need_rcu_barrier)
 473                rcu_barrier();
 474
 475        list_for_each_entry_safe(s, s2, release, list) {
 476#ifdef SLAB_SUPPORTS_SYSFS
 477                sysfs_slab_remove(s);
 478#else
 479                slab_kmem_cache_release(s);
 480#endif
 481        }
 482}
 483
 484#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
 485/*
 486 * memcg_create_kmem_cache - Create a cache for a memory cgroup.
 487 * @memcg: The memory cgroup the new cache is for.
 488 * @root_cache: The parent of the new cache.
 489 *
 490 * This function attempts to create a kmem cache that will serve allocation
 491 * requests going from @memcg to @root_cache. The new cache inherits properties
 492 * from its parent.
 493 */
 494void memcg_create_kmem_cache(struct mem_cgroup *memcg,
 495                             struct kmem_cache *root_cache)
 496{
 497        static char memcg_name_buf[NAME_MAX + 1]; /* protected by slab_mutex */
 498        struct cgroup_subsys_state *css = &memcg->css;
 499        struct memcg_cache_array *arr;
 500        struct kmem_cache *s = NULL;
 501        char *cache_name;
 502        int idx;
 503
 504        get_online_cpus();
 505        get_online_mems();
 506
 507        mutex_lock(&slab_mutex);
 508
 509        /*
 510         * The memory cgroup could have been offlined while the cache
 511         * creation work was pending.
 512         */
 513        if (memcg->kmem_state != KMEM_ONLINE)
 514                goto out_unlock;
 515
 516        idx = memcg_cache_id(memcg);
 517        arr = rcu_dereference_protected(root_cache->memcg_params.memcg_caches,
 518                                        lockdep_is_held(&slab_mutex));
 519
 520        /*
 521         * Since per-memcg caches are created asynchronously on first
 522         * allocation (see memcg_kmem_get_cache()), several threads can try to
 523         * create the same cache, but only one of them may succeed.
 524         */
 525        if (arr->entries[idx])
 526                goto out_unlock;
 527
 528        cgroup_name(css->cgroup, memcg_name_buf, sizeof(memcg_name_buf));
 529        cache_name = kasprintf(GFP_KERNEL, "%s(%llu:%s)", root_cache->name,
 530                               css->serial_nr, memcg_name_buf);
 531        if (!cache_name)
 532                goto out_unlock;
 533
 534        s = create_cache(cache_name, root_cache->object_size,
 535                         root_cache->size, root_cache->align,
 536                         root_cache->flags & CACHE_CREATE_MASK,
 537                         root_cache->ctor, memcg, root_cache);
 538        /*
 539         * If we could not create a memcg cache, do not complain, because
 540         * that's not critical at all as we can always proceed with the root
 541         * cache.
 542         */
 543        if (IS_ERR(s)) {
 544                kfree(cache_name);
 545                goto out_unlock;
 546        }
 547
 548        list_add(&s->memcg_params.list, &root_cache->memcg_params.list);
 549
 550        /*
 551         * Since readers won't lock (see cache_from_memcg_idx()), we need a
 552         * barrier here to ensure nobody will see the kmem_cache partially
 553         * initialized.
 554         */
 555        smp_wmb();
 556        arr->entries[idx] = s;
 557
 558out_unlock:
 559        mutex_unlock(&slab_mutex);
 560
 561        put_online_mems();
 562        put_online_cpus();
 563}
 564
 565void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg)
 566{
 567        int idx;
 568        struct memcg_cache_array *arr;
 569        struct kmem_cache *s, *c;
 570
 571        idx = memcg_cache_id(memcg);
 572
 573        get_online_cpus();
 574        get_online_mems();
 575
 576        mutex_lock(&slab_mutex);
 577        list_for_each_entry(s, &slab_caches, list) {
 578                if (!is_root_cache(s))
 579                        continue;
 580
 581                arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
 582                                                lockdep_is_held(&slab_mutex));
 583                c = arr->entries[idx];
 584                if (!c)
 585                        continue;
 586
 587                __kmem_cache_shrink(c, true);
 588                arr->entries[idx] = NULL;
 589        }
 590        mutex_unlock(&slab_mutex);
 591
 592        put_online_mems();
 593        put_online_cpus();
 594}
 595
 596static int __shutdown_memcg_cache(struct kmem_cache *s,
 597                struct list_head *release, bool *need_rcu_barrier)
 598{
 599        BUG_ON(is_root_cache(s));
 600
 601        if (shutdown_cache(s, release, need_rcu_barrier))
 602                return -EBUSY;
 603
 604        list_del(&s->memcg_params.list);
 605        return 0;
 606}
 607
 608void memcg_destroy_kmem_caches(struct mem_cgroup *memcg)
 609{
 610        LIST_HEAD(release);
 611        bool need_rcu_barrier = false;
 612        struct kmem_cache *s, *s2;
 613
 614        get_online_cpus();
 615        get_online_mems();
 616
 617        mutex_lock(&slab_mutex);
 618        list_for_each_entry_safe(s, s2, &slab_caches, list) {
 619                if (is_root_cache(s) || s->memcg_params.memcg != memcg)
 620                        continue;
 621                /*
 622                 * The cgroup is about to be freed and therefore has no charges
 623                 * left. Hence, all its caches must be empty by now.
 624                 */
 625                BUG_ON(__shutdown_memcg_cache(s, &release, &need_rcu_barrier));
 626        }
 627        mutex_unlock(&slab_mutex);
 628
 629        put_online_mems();
 630        put_online_cpus();
 631
 632        release_caches(&release, need_rcu_barrier);
 633}
 634
 635static int shutdown_memcg_caches(struct kmem_cache *s,
 636                struct list_head *release, bool *need_rcu_barrier)
 637{
 638        struct memcg_cache_array *arr;
 639        struct kmem_cache *c, *c2;
 640        LIST_HEAD(busy);
 641        int i;
 642
 643        BUG_ON(!is_root_cache(s));
 644
 645        /*
 646         * First, shutdown active caches, i.e. caches that belong to online
 647         * memory cgroups.
 648         */
 649        arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
 650                                        lockdep_is_held(&slab_mutex));
 651        for_each_memcg_cache_index(i) {
 652                c = arr->entries[i];
 653                if (!c)
 654                        continue;
 655                if (__shutdown_memcg_cache(c, release, need_rcu_barrier))
 656                        /*
 657                         * The cache still has objects. Move it to a temporary
 658                         * list so as not to try to destroy it for a second
 659                         * time while iterating over inactive caches below.
 660                         */
 661                        list_move(&c->memcg_params.list, &busy);
 662                else
 663                        /*
 664                         * The cache is empty and will be destroyed soon. Clear
 665                         * the pointer to it in the memcg_caches array so that
 666                         * it will never be accessed even if the root cache
 667                         * stays alive.
 668                         */
 669                        arr->entries[i] = NULL;
 670        }
 671
 672        /*
 673         * Second, shutdown all caches left from memory cgroups that are now
 674         * offline.
 675         */
 676        list_for_each_entry_safe(c, c2, &s->memcg_params.list,
 677                                 memcg_params.list)
 678                __shutdown_memcg_cache(c, release, need_rcu_barrier);
 679
 680        list_splice(&busy, &s->memcg_params.list);
 681
 682        /*
 683         * A cache being destroyed must be empty. In particular, this means
 684         * that all per memcg caches attached to it must be empty too.
 685         */
 686        if (!list_empty(&s->memcg_params.list))
 687                return -EBUSY;
 688        return 0;
 689}
 690#else
 691static inline int shutdown_memcg_caches(struct kmem_cache *s,
 692                struct list_head *release, bool *need_rcu_barrier)
 693{
 694        return 0;
 695}
 696#endif /* CONFIG_MEMCG && !CONFIG_SLOB */
 697
 698void slab_kmem_cache_release(struct kmem_cache *s)
 699{
 700        __kmem_cache_release(s);
 701        destroy_memcg_params(s);
 702        kfree_const(s->name);
 703        kmem_cache_free(kmem_cache, s);
 704}
 705
 706void kmem_cache_destroy(struct kmem_cache *s)
 707{
 708        LIST_HEAD(release);
 709        bool need_rcu_barrier = false;
 710        int err;
 711
 712        if (unlikely(!s))
 713                return;
 714
 715        get_online_cpus();
 716        get_online_mems();
 717
 718        kasan_cache_destroy(s);
 719        mutex_lock(&slab_mutex);
 720
 721        s->refcount--;
 722        if (s->refcount)
 723                goto out_unlock;
 724
 725        err = shutdown_memcg_caches(s, &release, &need_rcu_barrier);
 726        if (!err)
 727                err = shutdown_cache(s, &release, &need_rcu_barrier);
 728
 729        if (err) {
 730                pr_err("kmem_cache_destroy %s: Slab cache still has objects\n",
 731                       s->name);
 732                dump_stack();
 733        }
 734out_unlock:
 735        mutex_unlock(&slab_mutex);
 736
 737        put_online_mems();
 738        put_online_cpus();
 739
 740        release_caches(&release, need_rcu_barrier);
 741}
 742EXPORT_SYMBOL(kmem_cache_destroy);
 743
 744/**
 745 * kmem_cache_shrink - Shrink a cache.
 746 * @cachep: The cache to shrink.
 747 *
 748 * Releases as many slabs as possible for a cache.
 749 * To help debugging, a zero exit status indicates all slabs were released.
 750 */
 751int kmem_cache_shrink(struct kmem_cache *cachep)
 752{
 753        int ret;
 754
 755        get_online_cpus();
 756        get_online_mems();
 757        kasan_cache_shrink(cachep);
 758        ret = __kmem_cache_shrink(cachep, false);
 759        put_online_mems();
 760        put_online_cpus();
 761        return ret;
 762}
 763EXPORT_SYMBOL(kmem_cache_shrink);
 764
 765bool slab_is_available(void)
 766{
 767        return slab_state >= UP;
 768}
 769
 770#ifndef CONFIG_SLOB
 771/* Create a cache during boot when no slab services are available yet */
 772void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size,
 773                unsigned long flags)
 774{
 775        int err;
 776
 777        s->name = name;
 778        s->size = s->object_size = size;
 779        s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size);
 780
 781        slab_init_memcg_params(s);
 782
 783        err = __kmem_cache_create(s, flags);
 784
 785        if (err)
 786                panic("Creation of kmalloc slab %s size=%zu failed. Reason %d\n",
 787                                        name, size, err);
 788
 789        s->refcount = -1;       /* Exempt from merging for now */
 790}
 791
 792struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size,
 793                                unsigned long flags)
 794{
 795        struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
 796
 797        if (!s)
 798                panic("Out of memory when creating slab %s\n", name);
 799
 800        create_boot_cache(s, name, size, flags);
 801        list_add(&s->list, &slab_caches);
 802        s->refcount = 1;
 803        return s;
 804}
 805
 806struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
 807EXPORT_SYMBOL(kmalloc_caches);
 808
 809#ifdef CONFIG_ZONE_DMA
 810struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
 811EXPORT_SYMBOL(kmalloc_dma_caches);
 812#endif
 813
 814/*
 815 * Conversion table for small slabs sizes / 8 to the index in the
 816 * kmalloc array. This is necessary for slabs < 192 since we have non power
 817 * of two cache sizes there. The size of larger slabs can be determined using
 818 * fls.
 819 */
 820static s8 size_index[24] = {
 821        3,      /* 8 */
 822        4,      /* 16 */
 823        5,      /* 24 */
 824        5,      /* 32 */
 825        6,      /* 40 */
 826        6,      /* 48 */
 827        6,      /* 56 */
 828        6,      /* 64 */
 829        1,      /* 72 */
 830        1,      /* 80 */
 831        1,      /* 88 */
 832        1,      /* 96 */
 833        7,      /* 104 */
 834        7,      /* 112 */
 835        7,      /* 120 */
 836        7,      /* 128 */
 837        2,      /* 136 */
 838        2,      /* 144 */
 839        2,      /* 152 */
 840        2,      /* 160 */
 841        2,      /* 168 */
 842        2,      /* 176 */
 843        2,      /* 184 */
 844        2       /* 192 */
 845};
 846
 847static inline int size_index_elem(size_t bytes)
 848{
 849        return (bytes - 1) / 8;
 850}
 851
 852/*
 853 * Find the kmem_cache structure that serves a given size of
 854 * allocation
 855 */
 856struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
 857{
 858        int index;
 859
 860        if (unlikely(size > KMALLOC_MAX_SIZE)) {
 861                WARN_ON_ONCE(!(flags & __GFP_NOWARN));
 862                return NULL;
 863        }
 864
 865        if (size <= 192) {
 866                if (!size)
 867                        return ZERO_SIZE_PTR;
 868
 869                index = size_index[size_index_elem(size)];
 870        } else
 871                index = fls(size - 1);
 872
 873#ifdef CONFIG_ZONE_DMA
 874        if (unlikely((flags & GFP_DMA)))
 875                return kmalloc_dma_caches[index];
 876
 877#endif
 878        return kmalloc_caches[index];
 879}
 880
 881/*
 882 * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time.
 883 * kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is
 884 * kmalloc-67108864.
 885 */
 886static struct {
 887        const char *name;
 888        unsigned long size;
 889} const kmalloc_info[] __initconst = {
 890        {NULL,                      0},         {"kmalloc-96",             96},
 891        {"kmalloc-192",           192},         {"kmalloc-8",               8},
 892        {"kmalloc-16",             16},         {"kmalloc-32",             32},
 893        {"kmalloc-64",             64},         {"kmalloc-128",           128},
 894        {"kmalloc-256",           256},         {"kmalloc-512",           512},
 895        {"kmalloc-1024",         1024},         {"kmalloc-2048",         2048},
 896        {"kmalloc-4096",         4096},         {"kmalloc-8192",         8192},
 897        {"kmalloc-16384",       16384},         {"kmalloc-32768",       32768},
 898        {"kmalloc-65536",       65536},         {"kmalloc-131072",     131072},
 899        {"kmalloc-262144",     262144},         {"kmalloc-524288",     524288},
 900        {"kmalloc-1048576",   1048576},         {"kmalloc-2097152",   2097152},
 901        {"kmalloc-4194304",   4194304},         {"kmalloc-8388608",   8388608},
 902        {"kmalloc-16777216", 16777216},         {"kmalloc-33554432", 33554432},
 903        {"kmalloc-67108864", 67108864}
 904};
 905
 906/*
 907 * Patch up the size_index table if we have strange large alignment
 908 * requirements for the kmalloc array. This is only the case for
 909 * MIPS it seems. The standard arches will not generate any code here.
 910 *
 911 * Largest permitted alignment is 256 bytes due to the way we
 912 * handle the index determination for the smaller caches.
 913 *
 914 * Make sure that nothing crazy happens if someone starts tinkering
 915 * around with ARCH_KMALLOC_MINALIGN
 916 */
 917void __init setup_kmalloc_cache_index_table(void)
 918{
 919        int i;
 920
 921        BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
 922                (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
 923
 924        for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
 925                int elem = size_index_elem(i);
 926
 927                if (elem >= ARRAY_SIZE(size_index))
 928                        break;
 929                size_index[elem] = KMALLOC_SHIFT_LOW;
 930        }
 931
 932        if (KMALLOC_MIN_SIZE >= 64) {
 933                /*
 934                 * The 96 byte size cache is not used if the alignment
 935                 * is 64 byte.
 936                 */
 937                for (i = 64 + 8; i <= 96; i += 8)
 938                        size_index[size_index_elem(i)] = 7;
 939
 940        }
 941
 942        if (KMALLOC_MIN_SIZE >= 128) {
 943                /*
 944                 * The 192 byte sized cache is not used if the alignment
 945                 * is 128 byte. Redirect kmalloc to use the 256 byte cache
 946                 * instead.
 947                 */
 948                for (i = 128 + 8; i <= 192; i += 8)
 949                        size_index[size_index_elem(i)] = 8;
 950        }
 951}
 952
 953static void __init new_kmalloc_cache(int idx, unsigned long flags)
 954{
 955        kmalloc_caches[idx] = create_kmalloc_cache(kmalloc_info[idx].name,
 956                                        kmalloc_info[idx].size, flags);
 957}
 958
 959/*
 960 * Create the kmalloc array. Some of the regular kmalloc arrays
 961 * may already have been created because they were needed to
 962 * enable allocations for slab creation.
 963 */
 964void __init create_kmalloc_caches(unsigned long flags)
 965{
 966        int i;
 967
 968        for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
 969                if (!kmalloc_caches[i])
 970                        new_kmalloc_cache(i, flags);
 971
 972                /*
 973                 * Caches that are not of the two-to-the-power-of size.
 974                 * These have to be created immediately after the
 975                 * earlier power of two caches
 976                 */
 977                if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6)
 978                        new_kmalloc_cache(1, flags);
 979                if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7)
 980                        new_kmalloc_cache(2, flags);
 981        }
 982
 983        /* Kmalloc array is now usable */
 984        slab_state = UP;
 985
 986#ifdef CONFIG_ZONE_DMA
 987        for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
 988                struct kmem_cache *s = kmalloc_caches[i];
 989
 990                if (s) {
 991                        int size = kmalloc_size(i);
 992                        char *n = kasprintf(GFP_NOWAIT,
 993                                 "dma-kmalloc-%d", size);
 994
 995                        BUG_ON(!n);
 996                        kmalloc_dma_caches[i] = create_kmalloc_cache(n,
 997                                size, SLAB_CACHE_DMA | flags);
 998                }
 999        }
1000#endif
1001}
1002#endif /* !CONFIG_SLOB */
1003
1004/*
1005 * To avoid unnecessary overhead, we pass through large allocation requests
1006 * directly to the page allocator. We use __GFP_COMP, because we will need to
1007 * know the allocation order to free the pages properly in kfree.
1008 */
1009void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
1010{
1011        void *ret;
1012        struct page *page;
1013
1014        flags |= __GFP_COMP;
1015        page = alloc_pages(flags, order);
1016        ret = page ? page_address(page) : NULL;
1017        kmemleak_alloc(ret, size, 1, flags);
1018        kasan_kmalloc_large(ret, size, flags);
1019        return ret;
1020}
1021EXPORT_SYMBOL(kmalloc_order);
1022
1023#ifdef CONFIG_TRACING
1024void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
1025{
1026        void *ret = kmalloc_order(size, flags, order);
1027        trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags);
1028        return ret;
1029}
1030EXPORT_SYMBOL(kmalloc_order_trace);
1031#endif
1032
1033#ifdef CONFIG_SLAB_FREELIST_RANDOM
1034/* Randomize a generic freelist */
1035static void freelist_randomize(struct rnd_state *state, unsigned int *list,
1036                        size_t count)
1037{
1038        size_t i;
1039        unsigned int rand;
1040
1041        for (i = 0; i < count; i++)
1042                list[i] = i;
1043
1044        /* Fisher-Yates shuffle */
1045        for (i = count - 1; i > 0; i--) {
1046                rand = prandom_u32_state(state);
1047                rand %= (i + 1);
1048                swap(list[i], list[rand]);
1049        }
1050}
1051
1052/* Create a random sequence per cache */
1053int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
1054                                    gfp_t gfp)
1055{
1056        struct rnd_state state;
1057
1058        if (count < 2 || cachep->random_seq)
1059                return 0;
1060
1061        cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp);
1062        if (!cachep->random_seq)
1063                return -ENOMEM;
1064
1065        /* Get best entropy at this stage of boot */
1066        prandom_seed_state(&state, get_random_long());
1067
1068        freelist_randomize(&state, cachep->random_seq, count);
1069        return 0;
1070}
1071
1072/* Destroy the per-cache random freelist sequence */
1073void cache_random_seq_destroy(struct kmem_cache *cachep)
1074{
1075        kfree(cachep->random_seq);
1076        cachep->random_seq = NULL;
1077}
1078#endif /* CONFIG_SLAB_FREELIST_RANDOM */
1079
1080#ifdef CONFIG_SLABINFO
1081
1082#ifdef CONFIG_SLAB
1083#define SLABINFO_RIGHTS (S_IWUSR | S_IRUSR)
1084#else
1085#define SLABINFO_RIGHTS S_IRUSR
1086#endif
1087
1088static void print_slabinfo_header(struct seq_file *m)
1089{
1090        /*
1091         * Output format version, so at least we can change it
1092         * without _too_ many complaints.
1093         */
1094#ifdef CONFIG_DEBUG_SLAB
1095        seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
1096#else
1097        seq_puts(m, "slabinfo - version: 2.1\n");
1098#endif
1099        seq_puts(m, "# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
1100        seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
1101        seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
1102#ifdef CONFIG_DEBUG_SLAB
1103        seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
1104        seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
1105#endif
1106        seq_putc(m, '\n');
1107}
1108
1109void *slab_start(struct seq_file *m, loff_t *pos)
1110{
1111        mutex_lock(&slab_mutex);
1112        return seq_list_start(&slab_caches, *pos);
1113}
1114
1115void *slab_next(struct seq_file *m, void *p, loff_t *pos)
1116{
1117        return seq_list_next(p, &slab_caches, pos);
1118}
1119
1120void slab_stop(struct seq_file *m, void *p)
1121{
1122        mutex_unlock(&slab_mutex);
1123}
1124
1125static void
1126memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
1127{
1128        struct kmem_cache *c;
1129        struct slabinfo sinfo;
1130
1131        if (!is_root_cache(s))
1132                return;
1133
1134        for_each_memcg_cache(c, s) {
1135                memset(&sinfo, 0, sizeof(sinfo));
1136                get_slabinfo(c, &sinfo);
1137
1138                info->active_slabs += sinfo.active_slabs;
1139                info->num_slabs += sinfo.num_slabs;
1140                info->shared_avail += sinfo.shared_avail;
1141                info->active_objs += sinfo.active_objs;
1142                info->num_objs += sinfo.num_objs;
1143        }
1144}
1145
1146static void cache_show(struct kmem_cache *s, struct seq_file *m)
1147{
1148        struct slabinfo sinfo;
1149
1150        memset(&sinfo, 0, sizeof(sinfo));
1151        get_slabinfo(s, &sinfo);
1152
1153        memcg_accumulate_slabinfo(s, &sinfo);
1154
1155        seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
1156                   cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size,
1157                   sinfo.objects_per_slab, (1 << sinfo.cache_order));
1158
1159        seq_printf(m, " : tunables %4u %4u %4u",
1160                   sinfo.limit, sinfo.batchcount, sinfo.shared);
1161        seq_printf(m, " : slabdata %6lu %6lu %6lu",
1162                   sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
1163        slabinfo_show_stats(m, s);
1164        seq_putc(m, '\n');
1165}
1166
1167static int slab_show(struct seq_file *m, void *p)
1168{
1169        struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
1170
1171        if (p == slab_caches.next)
1172                print_slabinfo_header(m);
1173        if (is_root_cache(s))
1174                cache_show(s, m);
1175        return 0;
1176}
1177
1178#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
1179int memcg_slab_show(struct seq_file *m, void *p)
1180{
1181        struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
1182        struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
1183
1184        if (p == slab_caches.next)
1185                print_slabinfo_header(m);
1186        if (!is_root_cache(s) && s->memcg_params.memcg == memcg)
1187                cache_show(s, m);
1188        return 0;
1189}
1190#endif
1191
1192/*
1193 * slabinfo_op - iterator that generates /proc/slabinfo
1194 *
1195 * Output layout:
1196 * cache-name
1197 * num-active-objs
1198 * total-objs
1199 * object size
1200 * num-active-slabs
1201 * total-slabs
1202 * num-pages-per-slab
1203 * + further values on SMP and with statistics enabled
1204 */
1205static const struct seq_operations slabinfo_op = {
1206        .start = slab_start,
1207        .next = slab_next,
1208        .stop = slab_stop,
1209        .show = slab_show,
1210};
1211
1212static int slabinfo_open(struct inode *inode, struct file *file)
1213{
1214        return seq_open(file, &slabinfo_op);
1215}
1216
1217static const struct file_operations proc_slabinfo_operations = {
1218        .open           = slabinfo_open,
1219        .read           = seq_read,
1220        .write          = slabinfo_write,
1221        .llseek         = seq_lseek,
1222        .release        = seq_release,
1223};
1224
1225static int __init slab_proc_init(void)
1226{
1227        proc_create("slabinfo", SLABINFO_RIGHTS, NULL,
1228                                                &proc_slabinfo_operations);
1229        return 0;
1230}
1231module_init(slab_proc_init);
1232#endif /* CONFIG_SLABINFO */
1233
1234static __always_inline void *__do_krealloc(const void *p, size_t new_size,
1235                                           gfp_t flags)
1236{
1237        void *ret;
1238        size_t ks = 0;
1239
1240        if (p)
1241                ks = ksize(p);
1242
1243        if (ks >= new_size) {
1244                kasan_krealloc((void *)p, new_size, flags);
1245                return (void *)p;
1246        }
1247
1248        ret = kmalloc_track_caller(new_size, flags);
1249        if (ret && p)
1250                memcpy(ret, p, ks);
1251
1252        return ret;
1253}
1254
1255/**
1256 * __krealloc - like krealloc() but don't free @p.
1257 * @p: object to reallocate memory for.
1258 * @new_size: how many bytes of memory are required.
1259 * @flags: the type of memory to allocate.
1260 *
1261 * This function is like krealloc() except it never frees the originally
1262 * allocated buffer. Use this if you don't want to free the buffer immediately
1263 * like, for example, with RCU.
1264 */
1265void *__krealloc(const void *p, size_t new_size, gfp_t flags)
1266{
1267        if (unlikely(!new_size))
1268                return ZERO_SIZE_PTR;
1269
1270        return __do_krealloc(p, new_size, flags);
1271
1272}
1273EXPORT_SYMBOL(__krealloc);
1274
1275/**
1276 * krealloc - reallocate memory. The contents will remain unchanged.
1277 * @p: object to reallocate memory for.
1278 * @new_size: how many bytes of memory are required.
1279 * @flags: the type of memory to allocate.
1280 *
1281 * The contents of the object pointed to are preserved up to the
1282 * lesser of the new and old sizes.  If @p is %NULL, krealloc()
1283 * behaves exactly like kmalloc().  If @new_size is 0 and @p is not a
1284 * %NULL pointer, the object pointed to is freed.
1285 */
1286void *krealloc(const void *p, size_t new_size, gfp_t flags)
1287{
1288        void *ret;
1289
1290        if (unlikely(!new_size)) {
1291                kfree(p);
1292                return ZERO_SIZE_PTR;
1293        }
1294
1295        ret = __do_krealloc(p, new_size, flags);
1296        if (ret && p != ret)
1297                kfree(p);
1298
1299        return ret;
1300}
1301EXPORT_SYMBOL(krealloc);
1302
1303/**
1304 * kzfree - like kfree but zero memory
1305 * @p: object to free memory of
1306 *
1307 * The memory of the object @p points to is zeroed before freed.
1308 * If @p is %NULL, kzfree() does nothing.
1309 *
1310 * Note: this function zeroes the whole allocated buffer which can be a good
1311 * deal bigger than the requested buffer size passed to kmalloc(). So be
1312 * careful when using this function in performance sensitive code.
1313 */
1314void kzfree(const void *p)
1315{
1316        size_t ks;
1317        void *mem = (void *)p;
1318
1319        if (unlikely(ZERO_OR_NULL_PTR(mem)))
1320                return;
1321        ks = ksize(mem);
1322        memset(mem, 0, ks);
1323        kfree(mem);
1324}
1325EXPORT_SYMBOL(kzfree);
1326
1327/* Tracepoints definitions. */
1328EXPORT_TRACEPOINT_SYMBOL(kmalloc);
1329EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
1330EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
1331EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
1332EXPORT_TRACEPOINT_SYMBOL(kfree);
1333EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);
1334