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
  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 {
 169         struct kmem_cache *s = NULL;
 170         int err = 0;
 171
 172         get_online_cpus();
 173         mutex_lock(&slab_mutex);
 174
 175         if (!kmem_cache_sanity_check(memcg, name, size) == 0)
 176                 goto out_locked;
 177
 178         /*
 179          * Some allocators will constraint the set of valid flags to a subset
 180          * of all flags. We expect them to define CACHE_CREATE_MASK in this
 181          * case, and we'll just provide them with a sanitized version of the
 182          * passed flags.
 183          */
 184         flags &= CACHE_CREATE_MASK;
 185
 186         s = __kmem_cache_alias(memcg, name, size, align, flags, ctor);
 187         if (s)
 188                 goto out_locked;
 189
 190         s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
 191         if (s) {
 192                 s->object_size = s->size = size;
 193                 s->align = calculate_alignment(flags, align, size);
 194                 s->ctor = ctor;
 195
 196                 if (memcg_register_cache(memcg, s)) {
 197                         kmem_cache_free(kmem_cache, s);
 198                         err = -ENOMEM;
 199                         goto out_locked;
 200                 }
 201
 202                 s->name = kstrdup(name, GFP_KERNEL);
 203                 if (!s->name) {
 204                         kmem_cache_free(kmem_cache, s);
 205                         err = -ENOMEM;
 206                         goto out_locked;
 207                 }
 208
 209                 err = __kmem_cache_create(s, flags);
 210                 if (!err) {
 211                         s->refcount = 1;
 212                         list_add(&s->list, &slab_caches);
 213                         memcg_cache_list_add(memcg, s);
 214                 } else {
 215                         kfree(s->name);
 216                         kmem_cache_free(kmem_cache, s);
 217                 }
 218         } else
 219                 err = -ENOMEM;
 220
 221 out_locked:
 222         mutex_unlock(&slab_mutex);
 223         put_online_cpus();
 224
 225         if (err) {
 226
 227                 if (flags & SLAB_PANIC)
 228                         panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
 229                                 name, err);
 230                 else {
 231                         printk(KERN_WARNING "kmem_cache_create(%s) failed with error %d",
 232                                 name, err);
 233                         dump_stack();
 234                 }
 235
 236                 return NULL;
 237         }
 238
 239         return s;
 240 }
 241
 242 struct kmem_cache *
 243 kmem_cache_create(const char *name, size_t size, size_t align,
 244                   unsigned long flags, void (*ctor)(void *))
 245 {
 246         return kmem_cache_create_memcg(NULL, name, size, align, flags, ctor);
 247 }
 248 EXPORT_SYMBOL(kmem_cache_create);
 249
 250 void kmem_cache_destroy(struct kmem_cache *s)
 251 {
 252         get_online_cpus();
 253         mutex_lock(&slab_mutex);
 254         s->refcount--;
 255         if (!s->refcount) {
 256                 list_del(&s->list);
 257
 258                 if (!__kmem_cache_shutdown(s)) {
 259                         mutex_unlock(&slab_mutex);
 260                         if (s->flags & SLAB_DESTROY_BY_RCU)
 261                                 rcu_barrier();
 262
 263                         memcg_release_cache(s);
 264                         kfree(s->name);
 265                         kmem_cache_free(kmem_cache, s);
 266                 } else {
 267                         list_add(&s->list, &slab_caches);
 268                         mutex_unlock(&slab_mutex);
 269                         printk(KERN_ERR "kmem_cache_destroy %s: Slab cache still has objects\n",
 270                                 s->name);
 271                         dump_stack();
 272                 }
 273         } else {
 274                 mutex_unlock(&slab_mutex);
 275         }
 276         put_online_cpus();
 277 }
 278 EXPORT_SYMBOL(kmem_cache_destroy);
 279
 280 int slab_is_available(void)
 281 {
 282         return slab_state >= UP;
 283 }
 284
 285 #ifndef CONFIG_SLOB
 286 /* Create a cache during boot when no slab services are available yet */
 287 void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size,
 288                 unsigned long flags)
 289 {
 290         int err;
 291
 292         s->name = name;
 293         s->size = s->object_size = size;
 294         s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size);
 295         err = __kmem_cache_create(s, flags);
 296
 297         if (err)
 298                 panic("Creation of kmalloc slab %s size=%zd failed. Reason %d\n",
 299                                         name, size, err);
 300
 301         s->refcount = -1;       /* Exempt from merging for now */
 302 }
 303
 304 struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size,
 305                                 unsigned long flags)
 306 {
 307         struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
 308
 309         if (!s)
 310                 panic("Out of memory when creating slab %s\n", name);
 311
 312         create_boot_cache(s, name, size, flags);
 313         list_add(&s->list, &slab_caches);
 314         s->refcount = 1;
 315         return s;
 316 }
 317
 318 #endif /* !CONFIG_SLOB */
 319
 320
 321 #ifdef CONFIG_SLABINFO
 322 static void print_slabinfo_header(struct seq_file *m)
 323 {
 324         /*
 325          * Output format version, so at least we can change it
 326          * without _too_ many complaints.
 327          */
 328 #ifdef CONFIG_DEBUG_SLAB
 329         seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
 330 #else
 331         seq_puts(m, "slabinfo - version: 2.1\n");
 332 #endif
 333         seq_puts(m, "# name            <active_objs> <num_objs> <objsize> "
 334                  "<objperslab> <pagesperslab>");
 335         seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
 336         seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
 337 #ifdef CONFIG_DEBUG_SLAB
 338         seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
 339                  "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
 340         seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
 341 #endif
 342         seq_putc(m, '\n');
 343 }
 344
 345 static void *s_start(struct seq_file *m, loff_t *pos)
 346 {
 347         loff_t n = *pos;
 348
 349         mutex_lock(&slab_mutex);
 350         if (!n)
 351                 print_slabinfo_header(m);
 352
 353         return seq_list_start(&slab_caches, *pos);
 354 }
 355
 356 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
 357 {
 358         return seq_list_next(p, &slab_caches, pos);
 359 }
 360
 361 static void s_stop(struct seq_file *m, void *p)
 362 {
 363         mutex_unlock(&slab_mutex);
 364 }
 365
 366 static int s_show(struct seq_file *m, void *p)
 367 {
 368         struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
 369         struct slabinfo sinfo;
 370
 371         memset(&sinfo, 0, sizeof(sinfo));
 372         get_slabinfo(s, &sinfo);
 373
 374         seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
 375                    s->name, sinfo.active_objs, sinfo.num_objs, s->size,
 376                    sinfo.objects_per_slab, (1 << sinfo.cache_order));
 377
 378         seq_printf(m, " : tunables %4u %4u %4u",
 379                    sinfo.limit, sinfo.batchcount, sinfo.shared);
 380         seq_printf(m, " : slabdata %6lu %6lu %6lu",
 381                    sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
 382         slabinfo_show_stats(m, s);
 383         seq_putc(m, '\n');
 384         return 0;
 385 }
 386
 387 /*
 388  * slabinfo_op - iterator that generates /proc/slabinfo
 389  *
 390  * Output layout:
 391  * cache-name
 392  * num-active-objs
 393  * total-objs
 394  * object size
 395  * num-active-slabs
 396  * total-slabs
 397  * num-pages-per-slab
 398  * + further values on SMP and with statistics enabled
 399  */
 400 static const struct seq_operations slabinfo_op = {
 401         .start = s_start,
 402         .next = s_next,
 403         .stop = s_stop,
 404         .show = s_show,
 405 };
 406
 407 static int slabinfo_open(struct inode *inode, struct file *file)
 408 {
 409         return seq_open(file, &slabinfo_op);
 410 }
 411
 412 static const struct file_operations proc_slabinfo_operations = {
 413         .open           = slabinfo_open,
 414         .read           = seq_read,
 415         .write          = slabinfo_write,
 416         .llseek         = seq_lseek,
 417         .release        = seq_release,
 418 };
 419
 420 static int __init slab_proc_init(void)
 421 {
 422         proc_create("slabinfo", S_IRUSR, NULL, &proc_slabinfo_operations);
 423         return 0;
 424 }
 425 module_init(slab_proc_init);
 426 #endif /* CONFIG_SLABINFO */