FreeBSD/Linux Kernel Cross Reference
sys/mm/slab_common.c

     /*
      * Slab allocator functions that are independent of the allocator strategy
      *
      * (C) 2012 Christoph Lameter <cl@linux.com>
      */
     #include <linux/slab.h>
     
     #include <linux/mm.h>
     #include <linux/poison.h>
    #include <linux/interrupt.h>
    #include <linux/memory.h>
    #include <linux/compiler.h>
    #include <linux/module.h>
    #include <linux/cpu.h>
    #include <linux/uaccess.h>
    #include <linux/seq_file.h>
    #include <linux/proc_fs.h>
    #include <asm/cacheflush.h>
    #include <asm/tlbflush.h>
    #include <asm/page.h>
    #include <linux/memcontrol.h>
    
    #include "slab.h"
    
    enum slab_state slab_state;
    LIST_HEAD(slab_caches);
    DEFINE_MUTEX(slab_mutex);
    struct kmem_cache *kmem_cache;
    
    #ifdef CONFIG_DEBUG_VM
    static int kmem_cache_sanity_check(struct mem_cgroup *memcg, const char *name,
                                       size_t size)
    {
            struct kmem_cache *s = NULL;
    
            if (!name || in_interrupt() || size < sizeof(void *) ||
                    size > KMALLOC_MAX_SIZE) {
                    pr_err("kmem_cache_create(%s) integrity check failed\n", name);
                    return -EINVAL;
            }
    
            list_for_each_entry(s, &slab_caches, list) {
                    char tmp;
                    int res;
    
                    /*
                     * This happens when the module gets unloaded and doesn't
                     * destroy its slab cache and no-one else reuses the vmalloc
                     * area of the module.  Print a warning.
                     */
                    res = probe_kernel_address(s->name, tmp);
                    if (res) {
                            pr_err("Slab cache with size %d has lost its name\n",
                                   s->object_size);
                            continue;
                    }
    
                    /*
                     * For simplicity, we won't check this in the list of memcg
                     * caches. We have control over memcg naming, and if there
                     * aren't duplicates in the global list, there won't be any
                     * duplicates in the memcg lists as well.
                     */
                    if (!memcg && !strcmp(s->name, name)) {
                            pr_err("%s (%s): Cache name already exists.\n",
                                   __func__, name);
                            dump_stack();
                            s = NULL;
                            return -EINVAL;
                    }
            }
    
            WARN_ON(strchr(name, ' '));     /* It confuses parsers */
            return 0;
    }
    #else
    static inline int kmem_cache_sanity_check(struct mem_cgroup *memcg,
                                              const char *name, size_t size)
    {
            return 0;
    }
    #endif
    
    #ifdef CONFIG_MEMCG_KMEM
    int memcg_update_all_caches(int num_memcgs)
    {
            struct kmem_cache *s;
            int ret = 0;
            mutex_lock(&slab_mutex);
    
            list_for_each_entry(s, &slab_caches, list) {
                    if (!is_root_cache(s))
                            continue;
    
                    ret = memcg_update_cache_size(s, num_memcgs);
                    /*
                     * See comment in memcontrol.c, memcg_update_cache_size:
                     * Instead of freeing the memory, we'll just leave the caches
                     * up to this point in an updated state.
                    */
                   if (ret)
                           goto out;
           }
   
           memcg_update_array_size(num_memcgs);
   out:
           mutex_unlock(&slab_mutex);
           return ret;
   }
   #endif
   
   /*
    * Figure out what the alignment of the objects will be given a set of
    * flags, a user specified alignment and the size of the objects.
    */
   unsigned long calculate_alignment(unsigned long flags,
                   unsigned long align, unsigned long size)
   {
           /*
            * If the user wants hardware cache aligned objects then follow that
            * suggestion if the object is sufficiently large.
            *
            * The hardware cache alignment cannot override the specified
            * alignment though. If that is greater then use it.
            */
           if (flags & SLAB_HWCACHE_ALIGN) {
                   unsigned long ralign = cache_line_size();
                   while (size <= ralign / 2)
                           ralign /= 2;
                   align = max(align, ralign);
           }
   
           if (align < ARCH_SLAB_MINALIGN)
                   align = ARCH_SLAB_MINALIGN;
   
           return ALIGN(align, sizeof(void *));
   }
   
   
   /*
    * kmem_cache_create - Create a cache.
    * @name: A string which is used in /proc/slabinfo to identify this cache.
    * @size: The size of objects to be created in this cache.
    * @align: The required alignment for the objects.
    * @flags: SLAB flags
    * @ctor: A constructor for the objects.
    *
    * Returns a ptr to the cache on success, NULL on failure.
    * Cannot be called within a interrupt, but can be interrupted.
    * The @ctor is run when new pages are allocated by the cache.
    *
    * The flags are
    *
    * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
    * to catch references to uninitialised memory.
    *
    * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
    * for buffer overruns.
    *
    * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
    * cacheline.  This can be beneficial if you're counting cycles as closely
    * as davem.
    */
   
   struct kmem_cache *
   kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
                           size_t align, unsigned long flags, void (*ctor)(void *),
                           struct kmem_cache *parent_cache)
   {
           struct kmem_cache *s = NULL;
           int err = 0;
   
           get_online_cpus();
           mutex_lock(&slab_mutex);
   
           if (!kmem_cache_sanity_check(memcg, name, size) == 0)
                   goto out_locked;
   
           /*
            * Some allocators will constraint the set of valid flags to a subset
            * of all flags. We expect them to define CACHE_CREATE_MASK in this
            * case, and we'll just provide them with a sanitized version of the
            * passed flags.
            */
           flags &= CACHE_CREATE_MASK;
   
           s = __kmem_cache_alias(memcg, name, size, align, flags, ctor);
           if (s)
                   goto out_locked;
   
           s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
           if (s) {
                   s->object_size = s->size = size;
                   s->align = calculate_alignment(flags, align, size);
                   s->ctor = ctor;
   
                   if (memcg_register_cache(memcg, s, parent_cache)) {
                           kmem_cache_free(kmem_cache, s);
                           err = -ENOMEM;
                           goto out_locked;
                   }
   
                   s->name = kstrdup(name, GFP_KERNEL);
                   if (!s->name) {
                           kmem_cache_free(kmem_cache, s);
                           err = -ENOMEM;
                           goto out_locked;
                   }
   
                   err = __kmem_cache_create(s, flags);
                   if (!err) {
                           s->refcount = 1;
                           list_add(&s->list, &slab_caches);
                           memcg_cache_list_add(memcg, s);
                   } else {
                           kfree(s->name);
                           kmem_cache_free(kmem_cache, s);
                   }
           } else
                   err = -ENOMEM;
   
   out_locked:
           mutex_unlock(&slab_mutex);
           put_online_cpus();
   
           if (err) {
   
                   if (flags & SLAB_PANIC)
                           panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
                                   name, err);
                   else {
                           printk(KERN_WARNING "kmem_cache_create(%s) failed with error %d",
                                   name, err);
                           dump_stack();
                   }
   
                   return NULL;
           }
   
           return s;
   }
   
   struct kmem_cache *
   kmem_cache_create(const char *name, size_t size, size_t align,
                     unsigned long flags, void (*ctor)(void *))
   {
           return kmem_cache_create_memcg(NULL, name, size, align, flags, ctor, NULL);
   }
   EXPORT_SYMBOL(kmem_cache_create);
   
   void kmem_cache_destroy(struct kmem_cache *s)
   {
           /* Destroy all the children caches if we aren't a memcg cache */
           kmem_cache_destroy_memcg_children(s);
   
           get_online_cpus();
           mutex_lock(&slab_mutex);
           s->refcount--;
           if (!s->refcount) {
                   list_del(&s->list);
   
                   if (!__kmem_cache_shutdown(s)) {
                           mutex_unlock(&slab_mutex);
                           if (s->flags & SLAB_DESTROY_BY_RCU)
                                   rcu_barrier();
   
                           memcg_release_cache(s);
                           kfree(s->name);
                           kmem_cache_free(kmem_cache, s);
                   } else {
                           list_add(&s->list, &slab_caches);
                           mutex_unlock(&slab_mutex);
                           printk(KERN_ERR "kmem_cache_destroy %s: Slab cache still has objects\n",
                                   s->name);
                           dump_stack();
                   }
           } else {
                   mutex_unlock(&slab_mutex);
           }
           put_online_cpus();
   }
   EXPORT_SYMBOL(kmem_cache_destroy);
   
   int slab_is_available(void)
   {
           return slab_state >= UP;
   }
   
   #ifndef CONFIG_SLOB
   /* Create a cache during boot when no slab services are available yet */
   void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size,
                   unsigned long flags)
   {
           int err;
   
           s->name = name;
           s->size = s->object_size = size;
           s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size);
           err = __kmem_cache_create(s, flags);
   
           if (err)
                   panic("Creation of kmalloc slab %s size=%zd failed. Reason %d\n",
                                           name, size, err);
   
           s->refcount = -1;       /* Exempt from merging for now */
   }
   
   struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size,
                                   unsigned long flags)
   {
           struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
   
           if (!s)
                   panic("Out of memory when creating slab %s\n", name);
   
           create_boot_cache(s, name, size, flags);
           list_add(&s->list, &slab_caches);
           s->refcount = 1;
           return s;
   }
   
   #endif /* !CONFIG_SLOB */
   
   
   #ifdef CONFIG_SLABINFO
   void print_slabinfo_header(struct seq_file *m)
   {
           /*
            * Output format version, so at least we can change it
            * without _too_ many complaints.
            */
   #ifdef CONFIG_DEBUG_SLAB
           seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
   #else
           seq_puts(m, "slabinfo - version: 2.1\n");
   #endif
           seq_puts(m, "# name            <active_objs> <num_objs> <objsize> "
                    "<objperslab> <pagesperslab>");
           seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
           seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
   #ifdef CONFIG_DEBUG_SLAB
           seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
                    "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
           seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
   #endif
           seq_putc(m, '\n');
   }
   
   static void *s_start(struct seq_file *m, loff_t *pos)
   {
           loff_t n = *pos;
   
           mutex_lock(&slab_mutex);
           if (!n)
                   print_slabinfo_header(m);
   
           return seq_list_start(&slab_caches, *pos);
   }
   
   static void *s_next(struct seq_file *m, void *p, loff_t *pos)
   {
           return seq_list_next(p, &slab_caches, pos);
   }
   
   static void s_stop(struct seq_file *m, void *p)
   {
           mutex_unlock(&slab_mutex);
   }
   
   static void
   memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
   {
           struct kmem_cache *c;
           struct slabinfo sinfo;
           int i;
   
           if (!is_root_cache(s))
                   return;
   
           for_each_memcg_cache_index(i) {
                   c = cache_from_memcg(s, i);
                   if (!c)
                           continue;
   
                   memset(&sinfo, 0, sizeof(sinfo));
                   get_slabinfo(c, &sinfo);
   
                   info->active_slabs += sinfo.active_slabs;
                   info->num_slabs += sinfo.num_slabs;
                   info->shared_avail += sinfo.shared_avail;
                   info->active_objs += sinfo.active_objs;
                   info->num_objs += sinfo.num_objs;
           }
   }
   
   int cache_show(struct kmem_cache *s, struct seq_file *m)
   {
           struct slabinfo sinfo;
   
           memset(&sinfo, 0, sizeof(sinfo));
           get_slabinfo(s, &sinfo);
   
           memcg_accumulate_slabinfo(s, &sinfo);
   
           seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
                      cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size,
                      sinfo.objects_per_slab, (1 << sinfo.cache_order));
   
           seq_printf(m, " : tunables %4u %4u %4u",
                      sinfo.limit, sinfo.batchcount, sinfo.shared);
           seq_printf(m, " : slabdata %6lu %6lu %6lu",
                      sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
           slabinfo_show_stats(m, s);
           seq_putc(m, '\n');
           return 0;
   }
   
   static int s_show(struct seq_file *m, void *p)
   {
           struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
   
           if (!is_root_cache(s))
                   return 0;
           return cache_show(s, m);
   }
   
   /*
    * slabinfo_op - iterator that generates /proc/slabinfo
    *
    * Output layout:
    * cache-name
    * num-active-objs
    * total-objs
    * object size
    * num-active-slabs
    * total-slabs
    * num-pages-per-slab
    * + further values on SMP and with statistics enabled
    */
   static const struct seq_operations slabinfo_op = {
           .start = s_start,
           .next = s_next,
           .stop = s_stop,
           .show = s_show,
   };
   
   static int slabinfo_open(struct inode *inode, struct file *file)
   {
           return seq_open(file, &slabinfo_op);
   }
   
   static const struct file_operations proc_slabinfo_operations = {
           .open           = slabinfo_open,
           .read           = seq_read,
           .write          = slabinfo_write,
           .llseek         = seq_lseek,
           .release        = seq_release,
   };
   
   static int __init slab_proc_init(void)
   {
           proc_create("slabinfo", S_IRUSR, NULL, &proc_slabinfo_operations);
           return 0;
   }
   module_init(slab_proc_init);
   #endif /* CONFIG_SLABINFO */

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