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
  22 #include "slab.h"
  23
  24 enum slab_state slab_state;
  25 LIST_HEAD(slab_caches);
  26 DEFINE_MUTEX(slab_mutex);
  27 struct kmem_cache *kmem_cache;
  28
  29 #ifdef CONFIG_DEBUG_VM
  30 static int kmem_cache_sanity_check(const char *name, size_t size)
  31 {
  32         struct kmem_cache *s = NULL;
  33
  34         if (!name || in_interrupt() || size < sizeof(void *) ||
  35                 size > KMALLOC_MAX_SIZE) {
  36                 pr_err("kmem_cache_create(%s) integrity check failed\n", name);
  37                 return -EINVAL;
  38         }
  39
  40         list_for_each_entry(s, &slab_caches, list) {
  41                 char tmp;
  42                 int res;
  43
  44                 /*
  45                  * This happens when the module gets unloaded and doesn't
  46                  * destroy its slab cache and no-one else reuses the vmalloc
  47                  * area of the module.  Print a warning.
  48                  */
  49                 res = probe_kernel_address(s->name, tmp);
  50                 if (res) {
  51                         pr_err("Slab cache with size %d has lost its name\n",
  52                                s->object_size);
  53                         continue;
  54                 }
  55
  56                 if (!strcmp(s->name, name)) {
  57                         pr_err("%s (%s): Cache name already exists.\n",
  58                                __func__, name);
  59                         dump_stack();
  60                         s = NULL;
  61                         return -EINVAL;
  62                 }
  63         }
  64
  65         WARN_ON(strchr(name, ' '));     /* It confuses parsers */
  66         return 0;
  67 }
  68 #else
  69 static inline int kmem_cache_sanity_check(const char *name, size_t size)
  70 {
  71         return 0;
  72 }
  73 #endif
  74
  75 /*
  76  * kmem_cache_create - Create a cache.
  77  * @name: A string which is used in /proc/slabinfo to identify this cache.
  78  * @size: The size of objects to be created in this cache.
  79  * @align: The required alignment for the objects.
  80  * @flags: SLAB flags
  81  * @ctor: A constructor for the objects.
  82  *
  83  * Returns a ptr to the cache on success, NULL on failure.
  84  * Cannot be called within a interrupt, but can be interrupted.
  85  * The @ctor is run when new pages are allocated by the cache.
  86  *
  87  * The flags are
  88  *
  89  * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
  90  * to catch references to uninitialised memory.
  91  *
  92  * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
  93  * for buffer overruns.
  94  *
  95  * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
  96  * cacheline.  This can be beneficial if you're counting cycles as closely
  97  * as davem.
  98  */
  99
 100 struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align,
 101                 unsigned long flags, void (*ctor)(void *))
 102 {
 103         struct kmem_cache *s = NULL;
 104         int err = 0;
 105
 106         get_online_cpus();
 107         mutex_lock(&slab_mutex);
 108
 109         if (!kmem_cache_sanity_check(name, size) == 0)
 110                 goto out_locked;
 111
 112         /*
 113          * Some allocators will constraint the set of valid flags to a subset
 114          * of all flags. We expect them to define CACHE_CREATE_MASK in this
 115          * case, and we'll just provide them with a sanitized version of the
 116          * passed flags.
 117          */
 118         flags &= CACHE_CREATE_MASK;
 119
 120         s = __kmem_cache_alias(name, size, align, flags, ctor);
 121         if (s)
 122                 goto out_locked;
 123
 124         s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
 125         if (s) {
 126                 s->object_size = s->size = size;
 127                 s->align = align;
 128                 s->ctor = ctor;
 129                 s->name = kstrdup(name, GFP_KERNEL);
 130                 if (!s->name) {
 131                         kmem_cache_free(kmem_cache, s);
 132                         err = -ENOMEM;
 133                         goto out_locked;
 134                 }
 135
 136                 err = __kmem_cache_create(s, flags);
 137                 if (!err) {
 138
 139                         s->refcount = 1;
 140                         list_add(&s->list, &slab_caches);
 141
 142                 } else {
 143                         kfree(s->name);
 144                         kmem_cache_free(kmem_cache, s);
 145                 }
 146         } else
 147                 err = -ENOMEM;
 148
 149 out_locked:
 150         mutex_unlock(&slab_mutex);
 151         put_online_cpus();
 152
 153         if (err) {
 154
 155                 if (flags & SLAB_PANIC)
 156                         panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
 157                                 name, err);
 158                 else {
 159                         printk(KERN_WARNING "kmem_cache_create(%s) failed with error %d",
 160                                 name, err);
 161                         dump_stack();
 162                 }
 163
 164                 return NULL;
 165         }
 166
 167         return s;
 168 }
 169 EXPORT_SYMBOL(kmem_cache_create);
 170
 171 void kmem_cache_destroy(struct kmem_cache *s)
 172 {
 173         get_online_cpus();
 174         mutex_lock(&slab_mutex);
 175         s->refcount--;
 176         if (!s->refcount) {
 177                 list_del(&s->list);
 178
 179                 if (!__kmem_cache_shutdown(s)) {
 180                         mutex_unlock(&slab_mutex);
 181                         if (s->flags & SLAB_DESTROY_BY_RCU)
 182                                 rcu_barrier();
 183
 184                         kfree(s->name);
 185                         kmem_cache_free(kmem_cache, s);
 186                 } else {
 187                         list_add(&s->list, &slab_caches);
 188                         mutex_unlock(&slab_mutex);
 189                         printk(KERN_ERR "kmem_cache_destroy %s: Slab cache still has objects\n",
 190                                 s->name);
 191                         dump_stack();
 192                 }
 193         } else {
 194                 mutex_unlock(&slab_mutex);
 195         }
 196         put_online_cpus();
 197 }
 198 EXPORT_SYMBOL(kmem_cache_destroy);
 199
 200 int slab_is_available(void)
 201 {
 202         return slab_state >= UP;
 203 }
 204
 205 #ifdef CONFIG_SLABINFO
 206 static void print_slabinfo_header(struct seq_file *m)
 207 {
 208         /*
 209          * Output format version, so at least we can change it
 210          * without _too_ many complaints.
 211          */
 212 #ifdef CONFIG_DEBUG_SLAB
 213         seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
 214 #else
 215         seq_puts(m, "slabinfo - version: 2.1\n");
 216 #endif
 217         seq_puts(m, "# name            <active_objs> <num_objs> <objsize> "
 218                  "<objperslab> <pagesperslab>");
 219         seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
 220         seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
 221 #ifdef CONFIG_DEBUG_SLAB
 222         seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
 223                  "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
 224         seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
 225 #endif
 226         seq_putc(m, '\n');
 227 }
 228
 229 static void *s_start(struct seq_file *m, loff_t *pos)
 230 {
 231         loff_t n = *pos;
 232
 233         mutex_lock(&slab_mutex);
 234         if (!n)
 235                 print_slabinfo_header(m);
 236
 237         return seq_list_start(&slab_caches, *pos);
 238 }
 239
 240 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
 241 {
 242         return seq_list_next(p, &slab_caches, pos);
 243 }
 244
 245 static void s_stop(struct seq_file *m, void *p)
 246 {
 247         mutex_unlock(&slab_mutex);
 248 }
 249
 250 static int s_show(struct seq_file *m, void *p)
 251 {
 252         struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
 253         struct slabinfo sinfo;
 254
 255         memset(&sinfo, 0, sizeof(sinfo));
 256         get_slabinfo(s, &sinfo);
 257
 258         seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
 259                    s->name, sinfo.active_objs, sinfo.num_objs, s->size,
 260                    sinfo.objects_per_slab, (1 << sinfo.cache_order));
 261
 262         seq_printf(m, " : tunables %4u %4u %4u",
 263                    sinfo.limit, sinfo.batchcount, sinfo.shared);
 264         seq_printf(m, " : slabdata %6lu %6lu %6lu",
 265                    sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
 266         slabinfo_show_stats(m, s);
 267         seq_putc(m, '\n');
 268         return 0;
 269 }
 270
 271 /*
 272  * slabinfo_op - iterator that generates /proc/slabinfo
 273  *
 274  * Output layout:
 275  * cache-name
 276  * num-active-objs
 277  * total-objs
 278  * object size
 279  * num-active-slabs
 280  * total-slabs
 281  * num-pages-per-slab
 282  * + further values on SMP and with statistics enabled
 283  */
 284 static const struct seq_operations slabinfo_op = {
 285         .start = s_start,
 286         .next = s_next,
 287         .stop = s_stop,
 288         .show = s_show,
 289 };
 290
 291 static int slabinfo_open(struct inode *inode, struct file *file)
 292 {
 293         return seq_open(file, &slabinfo_op);
 294 }
 295
 296 static const struct file_operations proc_slabinfo_operations = {
 297         .open           = slabinfo_open,
 298         .read           = seq_read,
 299         .write          = slabinfo_write,
 300         .llseek         = seq_lseek,
 301         .release        = seq_release,
 302 };
 303
 304 static int __init slab_proc_init(void)
 305 {
 306         proc_create("slabinfo", S_IRUSR, NULL, &proc_slabinfo_operations);
 307         return 0;
 308 }
 309 module_init(slab_proc_init);
 310 #endif /* CONFIG_SLABINFO */