drivers/base/node.c

   1 /*
   2  * Basic Node interface support
   3  */
   4
   5 #include <linux/module.h>
   6 #include <linux/init.h>
   7 #include <linux/mm.h>
   8 #include <linux/memory.h>
   9 #include <linux/vmstat.h>
  10 #include <linux/node.h>
  11 #include <linux/hugetlb.h>
  12 #include <linux/compaction.h>
  13 #include <linux/cpumask.h>
  14 #include <linux/topology.h>
  15 #include <linux/nodemask.h>
  16 #include <linux/cpu.h>
  17 #include <linux/device.h>
  18 #include <linux/swap.h>
  19 #include <linux/slab.h>
  20
  21 static struct bus_type node_subsys = {
  22         .name = "node",
  23         .dev_name = "node",
  24 };
  25
  26
  27 static ssize_t node_read_cpumap(struct device *dev, int type, char *buf)
  28 {
  29         struct node *node_dev = to_node(dev);
  30         const struct cpumask *mask = cpumask_of_node(node_dev->dev.id);
  31         int len;
  32
  33         /* 2008/04/07: buf currently PAGE_SIZE, need 9 chars per 32 bits. */
  34         BUILD_BUG_ON((NR_CPUS/32 * 9) > (PAGE_SIZE-1));
  35
  36         len = type?
  37                 cpulist_scnprintf(buf, PAGE_SIZE-2, mask) :
  38                 cpumask_scnprintf(buf, PAGE_SIZE-2, mask);
  39         buf[len++] = '\n';
  40         buf[len] = '\0';
  41         return len;
  42 }
  43
  44 static inline ssize_t node_read_cpumask(struct device *dev,
  45                                 struct device_attribute *attr, char *buf)
  46 {
  47         return node_read_cpumap(dev, 0, buf);
  48 }
  49 static inline ssize_t node_read_cpulist(struct device *dev,
  50                                 struct device_attribute *attr, char *buf)
  51 {
  52         return node_read_cpumap(dev, 1, buf);
  53 }
  54
  55 static DEVICE_ATTR(cpumap,  S_IRUGO, node_read_cpumask, NULL);
  56 static DEVICE_ATTR(cpulist, S_IRUGO, node_read_cpulist, NULL);
  57
  58 #define K(x) ((x) << (PAGE_SHIFT - 10))
  59 static ssize_t node_read_meminfo(struct device *dev,
  60                         struct device_attribute *attr, char *buf)
  61 {
  62         int n;
  63         int nid = dev->id;
  64         struct sysinfo i;
  65
  66         si_meminfo_node(&i, nid);
  67         n = sprintf(buf,
  68                        "Node %d MemTotal:       %8lu kB\n"
  69                        "Node %d MemFree:        %8lu kB\n"
  70                        "Node %d MemUsed:        %8lu kB\n"
  71                        "Node %d Active:         %8lu kB\n"
  72                        "Node %d Inactive:       %8lu kB\n"
  73                        "Node %d Active(anon):   %8lu kB\n"
  74                        "Node %d Inactive(anon): %8lu kB\n"
  75                        "Node %d Active(file):   %8lu kB\n"
  76                        "Node %d Inactive(file): %8lu kB\n"
  77                        "Node %d Unevictable:    %8lu kB\n"
  78                        "Node %d Mlocked:        %8lu kB\n",
  79                        nid, K(i.totalram),
  80                        nid, K(i.freeram),
  81                        nid, K(i.totalram - i.freeram),
  82                        nid, K(node_page_state(nid, NR_ACTIVE_ANON) +
  83                                 node_page_state(nid, NR_ACTIVE_FILE)),
  84                        nid, K(node_page_state(nid, NR_INACTIVE_ANON) +
  85                                 node_page_state(nid, NR_INACTIVE_FILE)),
  86                        nid, K(node_page_state(nid, NR_ACTIVE_ANON)),
  87                        nid, K(node_page_state(nid, NR_INACTIVE_ANON)),
  88                        nid, K(node_page_state(nid, NR_ACTIVE_FILE)),
  89                        nid, K(node_page_state(nid, NR_INACTIVE_FILE)),
  90                        nid, K(node_page_state(nid, NR_UNEVICTABLE)),
  91                        nid, K(node_page_state(nid, NR_MLOCK)));
  92
  93 #ifdef CONFIG_HIGHMEM
  94         n += sprintf(buf + n,
  95                        "Node %d HighTotal:      %8lu kB\n"
  96                        "Node %d HighFree:       %8lu kB\n"
  97                        "Node %d LowTotal:       %8lu kB\n"
  98                        "Node %d LowFree:        %8lu kB\n",
  99                        nid, K(i.totalhigh),
 100                        nid, K(i.freehigh),
 101                        nid, K(i.totalram - i.totalhigh),
 102                        nid, K(i.freeram - i.freehigh));
 103 #endif
 104         n += sprintf(buf + n,
 105                        "Node %d Dirty:          %8lu kB\n"
 106                        "Node %d Writeback:      %8lu kB\n"
 107                        "Node %d FilePages:      %8lu kB\n"
 108                        "Node %d Mapped:         %8lu kB\n"
 109                        "Node %d AnonPages:      %8lu kB\n"
 110                        "Node %d Shmem:          %8lu kB\n"
 111                        "Node %d KernelStack:    %8lu kB\n"
 112                        "Node %d PageTables:     %8lu kB\n"
 113                        "Node %d NFS_Unstable:   %8lu kB\n"
 114                        "Node %d Bounce:         %8lu kB\n"
 115                        "Node %d WritebackTmp:   %8lu kB\n"
 116                        "Node %d Slab:           %8lu kB\n"
 117                        "Node %d SReclaimable:   %8lu kB\n"
 118                        "Node %d SUnreclaim:     %8lu kB\n"
 119 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 120                        "Node %d AnonHugePages:  %8lu kB\n"
 121 #endif
 122                         ,
 123                        nid, K(node_page_state(nid, NR_FILE_DIRTY)),
 124                        nid, K(node_page_state(nid, NR_WRITEBACK)),
 125                        nid, K(node_page_state(nid, NR_FILE_PAGES)),
 126                        nid, K(node_page_state(nid, NR_FILE_MAPPED)),
 127 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 128                        nid, K(node_page_state(nid, NR_ANON_PAGES)
 129                         + node_page_state(nid, NR_ANON_TRANSPARENT_HUGEPAGES) *
 130                         HPAGE_PMD_NR),
 131 #else
 132                        nid, K(node_page_state(nid, NR_ANON_PAGES)),
 133 #endif
 134                        nid, K(node_page_state(nid, NR_SHMEM)),
 135                        nid, node_page_state(nid, NR_KERNEL_STACK) *
 136                                 THREAD_SIZE / 1024,
 137                        nid, K(node_page_state(nid, NR_PAGETABLE)),
 138                        nid, K(node_page_state(nid, NR_UNSTABLE_NFS)),
 139                        nid, K(node_page_state(nid, NR_BOUNCE)),
 140                        nid, K(node_page_state(nid, NR_WRITEBACK_TEMP)),
 141                        nid, K(node_page_state(nid, NR_SLAB_RECLAIMABLE) +
 142                                 node_page_state(nid, NR_SLAB_UNRECLAIMABLE)),
 143                        nid, K(node_page_state(nid, NR_SLAB_RECLAIMABLE)),
 144 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 145                        nid, K(node_page_state(nid, NR_SLAB_UNRECLAIMABLE))
 146                         , nid,
 147                         K(node_page_state(nid, NR_ANON_TRANSPARENT_HUGEPAGES) *
 148                         HPAGE_PMD_NR));
 149 #else
 150                        nid, K(node_page_state(nid, NR_SLAB_UNRECLAIMABLE)));
 151 #endif
 152         n += hugetlb_report_node_meminfo(nid, buf + n);
 153         return n;
 154 }
 155
 156 #undef K
 157 static DEVICE_ATTR(meminfo, S_IRUGO, node_read_meminfo, NULL);
 158
 159 static ssize_t node_read_numastat(struct device *dev,
 160                                 struct device_attribute *attr, char *buf)
 161 {
 162         return sprintf(buf,
 163                        "numa_hit %lu\n"
 164                        "numa_miss %lu\n"
 165                        "numa_foreign %lu\n"
 166                        "interleave_hit %lu\n"
 167                        "local_node %lu\n"
 168                        "other_node %lu\n",
 169                        node_page_state(dev->id, NUMA_HIT),
 170                        node_page_state(dev->id, NUMA_MISS),
 171                        node_page_state(dev->id, NUMA_FOREIGN),
 172                        node_page_state(dev->id, NUMA_INTERLEAVE_HIT),
 173                        node_page_state(dev->id, NUMA_LOCAL),
 174                        node_page_state(dev->id, NUMA_OTHER));
 175 }
 176 static DEVICE_ATTR(numastat, S_IRUGO, node_read_numastat, NULL);
 177
 178 static ssize_t node_read_vmstat(struct device *dev,
 179                                 struct device_attribute *attr, char *buf)
 180 {
 181         int nid = dev->id;
 182         int i;
 183         int n = 0;
 184
 185         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 186                 n += sprintf(buf+n, "%s %lu\n", vmstat_text[i],
 187                              node_page_state(nid, i));
 188
 189         return n;
 190 }
 191 static DEVICE_ATTR(vmstat, S_IRUGO, node_read_vmstat, NULL);
 192
 193 static ssize_t node_read_distance(struct device *dev,
 194                         struct device_attribute *attr, char * buf)
 195 {
 196         int nid = dev->id;
 197         int len = 0;
 198         int i;
 199
 200         /*
 201          * buf is currently PAGE_SIZE in length and each node needs 4 chars
 202          * at the most (distance + space or newline).
 203          */
 204         BUILD_BUG_ON(MAX_NUMNODES * 4 > PAGE_SIZE);
 205
 206         for_each_online_node(i)
 207                 len += sprintf(buf + len, "%s%d", i ? " " : "", node_distance(nid, i));
 208
 209         len += sprintf(buf + len, "\n");
 210         return len;
 211 }
 212 static DEVICE_ATTR(distance, S_IRUGO, node_read_distance, NULL);
 213
 214 #ifdef CONFIG_HUGETLBFS
 215 /*
 216  * hugetlbfs per node attributes registration interface:
 217  * When/if hugetlb[fs] subsystem initializes [sometime after this module],
 218  * it will register its per node attributes for all online nodes with
 219  * memory.  It will also call register_hugetlbfs_with_node(), below, to
 220  * register its attribute registration functions with this node driver.
 221  * Once these hooks have been initialized, the node driver will call into
 222  * the hugetlb module to [un]register attributes for hot-plugged nodes.
 223  */
 224 static node_registration_func_t __hugetlb_register_node;
 225 static node_registration_func_t __hugetlb_unregister_node;
 226
 227 static inline bool hugetlb_register_node(struct node *node)
 228 {
 229         if (__hugetlb_register_node &&
 230                         node_state(node->dev.id, N_HIGH_MEMORY)) {
 231                 __hugetlb_register_node(node);
 232                 return true;
 233         }
 234         return false;
 235 }
 236
 237 static inline void hugetlb_unregister_node(struct node *node)
 238 {
 239         if (__hugetlb_unregister_node)
 240                 __hugetlb_unregister_node(node);
 241 }
 242
 243 void register_hugetlbfs_with_node(node_registration_func_t doregister,
 244                                   node_registration_func_t unregister)
 245 {
 246         __hugetlb_register_node   = doregister;
 247         __hugetlb_unregister_node = unregister;
 248 }
 249 #else
 250 static inline void hugetlb_register_node(struct node *node) {}
 251
 252 static inline void hugetlb_unregister_node(struct node *node) {}
 253 #endif
 254
 255
 256 /*
 257  * register_node - Setup a sysfs device for a node.
 258  * @num - Node number to use when creating the device.
 259  *
 260  * Initialize and register the node device.
 261  */
 262 int register_node(struct node *node, int num, struct node *parent)
 263 {
 264         int error;
 265
 266         node->dev.id = num;
 267         node->dev.bus = &node_subsys;
 268         error = device_register(&node->dev);
 269
 270         if (!error){
 271                 device_create_file(&node->dev, &dev_attr_cpumap);
 272                 device_create_file(&node->dev, &dev_attr_cpulist);
 273                 device_create_file(&node->dev, &dev_attr_meminfo);
 274                 device_create_file(&node->dev, &dev_attr_numastat);
 275                 device_create_file(&node->dev, &dev_attr_distance);
 276                 device_create_file(&node->dev, &dev_attr_vmstat);
 277
 278                 scan_unevictable_register_node(node);
 279
 280                 hugetlb_register_node(node);
 281
 282                 compaction_register_node(node);
 283         }
 284         return error;
 285 }
 286
 287 /**
 288  * unregister_node - unregister a node device
 289  * @node: node going away
 290  *
 291  * Unregisters a node device @node.  All the devices on the node must be
 292  * unregistered before calling this function.
 293  */
 294 void unregister_node(struct node *node)
 295 {
 296         device_remove_file(&node->dev, &dev_attr_cpumap);
 297         device_remove_file(&node->dev, &dev_attr_cpulist);
 298         device_remove_file(&node->dev, &dev_attr_meminfo);
 299         device_remove_file(&node->dev, &dev_attr_numastat);
 300         device_remove_file(&node->dev, &dev_attr_distance);
 301         device_remove_file(&node->dev, &dev_attr_vmstat);
 302
 303         scan_unevictable_unregister_node(node);
 304         hugetlb_unregister_node(node);          /* no-op, if memoryless node */
 305
 306         device_unregister(&node->dev);
 307 }
 308
 309 struct node node_devices[MAX_NUMNODES];
 310
 311 /*
 312  * register cpu under node
 313  */
 314 int register_cpu_under_node(unsigned int cpu, unsigned int nid)
 315 {
 316         int ret;
 317         struct device *obj;
 318
 319         if (!node_online(nid))
 320                 return 0;
 321
 322         obj = get_cpu_device(cpu);
 323         if (!obj)
 324                 return 0;
 325
 326         ret = sysfs_create_link(&node_devices[nid].dev.kobj,
 327                                 &obj->kobj,
 328                                 kobject_name(&obj->kobj));
 329         if (ret)
 330                 return ret;
 331
 332         return sysfs_create_link(&obj->kobj,
 333                                  &node_devices[nid].dev.kobj,
 334                                  kobject_name(&node_devices[nid].dev.kobj));
 335 }
 336
 337 int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
 338 {
 339         struct device *obj;
 340
 341         if (!node_online(nid))
 342                 return 0;
 343
 344         obj = get_cpu_device(cpu);
 345         if (!obj)
 346                 return 0;
 347
 348         sysfs_remove_link(&node_devices[nid].dev.kobj,
 349                           kobject_name(&obj->kobj));
 350         sysfs_remove_link(&obj->kobj,
 351                           kobject_name(&node_devices[nid].dev.kobj));
 352
 353         return 0;
 354 }
 355
 356 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
 357 #define page_initialized(page)  (page->lru.next)
 358
 359 static int get_nid_for_pfn(unsigned long pfn)
 360 {
 361         struct page *page;
 362
 363         if (!pfn_valid_within(pfn))
 364                 return -1;
 365         page = pfn_to_page(pfn);
 366         if (!page_initialized(page))
 367                 return -1;
 368         return pfn_to_nid(pfn);
 369 }
 370
 371 /* register memory section under specified node if it spans that node */
 372 int register_mem_sect_under_node(struct memory_block *mem_blk, int nid)
 373 {
 374         int ret;
 375         unsigned long pfn, sect_start_pfn, sect_end_pfn;
 376
 377         if (!mem_blk)
 378                 return -EFAULT;
 379         if (!node_online(nid))
 380                 return 0;
 381
 382         sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
 383         sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr);
 384         sect_end_pfn += PAGES_PER_SECTION - 1;
 385         for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
 386                 int page_nid;
 387
 388                 page_nid = get_nid_for_pfn(pfn);
 389                 if (page_nid < 0)
 390                         continue;
 391                 if (page_nid != nid)
 392                         continue;
 393                 ret = sysfs_create_link_nowarn(&node_devices[nid].dev.kobj,
 394                                         &mem_blk->dev.kobj,
 395                                         kobject_name(&mem_blk->dev.kobj));
 396                 if (ret)
 397                         return ret;
 398
 399                 return sysfs_create_link_nowarn(&mem_blk->dev.kobj,
 400                                 &node_devices[nid].dev.kobj,
 401                                 kobject_name(&node_devices[nid].dev.kobj));
 402         }
 403         /* mem section does not span the specified node */
 404         return 0;
 405 }
 406
 407 /* unregister memory section under all nodes that it spans */
 408 int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
 409                                     unsigned long phys_index)
 410 {
 411         NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
 412         unsigned long pfn, sect_start_pfn, sect_end_pfn;
 413
 414         if (!mem_blk) {
 415                 NODEMASK_FREE(unlinked_nodes);
 416                 return -EFAULT;
 417         }
 418         if (!unlinked_nodes)
 419                 return -ENOMEM;
 420         nodes_clear(*unlinked_nodes);
 421
 422         sect_start_pfn = section_nr_to_pfn(phys_index);
 423         sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
 424         for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
 425                 int nid;
 426
 427                 nid = get_nid_for_pfn(pfn);
 428                 if (nid < 0)
 429                         continue;
 430                 if (!node_online(nid))
 431                         continue;
 432                 if (node_test_and_set(nid, *unlinked_nodes))
 433                         continue;
 434                 sysfs_remove_link(&node_devices[nid].dev.kobj,
 435                          kobject_name(&mem_blk->dev.kobj));
 436                 sysfs_remove_link(&mem_blk->dev.kobj,
 437                          kobject_name(&node_devices[nid].dev.kobj));
 438         }
 439         NODEMASK_FREE(unlinked_nodes);
 440         return 0;
 441 }
 442
 443 static int link_mem_sections(int nid)
 444 {
 445         unsigned long start_pfn = NODE_DATA(nid)->node_start_pfn;
 446         unsigned long end_pfn = start_pfn + NODE_DATA(nid)->node_spanned_pages;
 447         unsigned long pfn;
 448         struct memory_block *mem_blk = NULL;
 449         int err = 0;
 450
 451         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 452                 unsigned long section_nr = pfn_to_section_nr(pfn);
 453                 struct mem_section *mem_sect;
 454                 int ret;
 455
 456                 if (!present_section_nr(section_nr))
 457                         continue;
 458                 mem_sect = __nr_to_section(section_nr);
 459
 460                 /* same memblock ? */
 461                 if (mem_blk)
 462                         if ((section_nr >= mem_blk->start_section_nr) &&
 463                             (section_nr <= mem_blk->end_section_nr))
 464                                 continue;
 465
 466                 mem_blk = find_memory_block_hinted(mem_sect, mem_blk);
 467
 468                 ret = register_mem_sect_under_node(mem_blk, nid);
 469                 if (!err)
 470                         err = ret;
 471
 472                 /* discard ref obtained in find_memory_block() */
 473         }
 474
 475         if (mem_blk)
 476                 kobject_put(&mem_blk->dev.kobj);
 477         return err;
 478 }
 479
 480 #ifdef CONFIG_HUGETLBFS
 481 /*
 482  * Handle per node hstate attribute [un]registration on transistions
 483  * to/from memoryless state.
 484  */
 485 static void node_hugetlb_work(struct work_struct *work)
 486 {
 487         struct node *node = container_of(work, struct node, node_work);
 488
 489         /*
 490          * We only get here when a node transitions to/from memoryless state.
 491          * We can detect which transition occurred by examining whether the
 492          * node has memory now.  hugetlb_register_node() already check this
 493          * so we try to register the attributes.  If that fails, then the
 494          * node has transitioned to memoryless, try to unregister the
 495          * attributes.
 496          */
 497         if (!hugetlb_register_node(node))
 498                 hugetlb_unregister_node(node);
 499 }
 500
 501 static void init_node_hugetlb_work(int nid)
 502 {
 503         INIT_WORK(&node_devices[nid].node_work, node_hugetlb_work);
 504 }
 505
 506 static int node_memory_callback(struct notifier_block *self,
 507                                 unsigned long action, void *arg)
 508 {
 509         struct memory_notify *mnb = arg;
 510         int nid = mnb->status_change_nid;
 511
 512         switch (action) {
 513         case MEM_ONLINE:
 514         case MEM_OFFLINE:
 515                 /*
 516                  * offload per node hstate [un]registration to a work thread
 517                  * when transitioning to/from memoryless state.
 518                  */
 519                 if (nid != NUMA_NO_NODE)
 520                         schedule_work(&node_devices[nid].node_work);
 521                 break;
 522
 523         case MEM_GOING_ONLINE:
 524         case MEM_GOING_OFFLINE:
 525         case MEM_CANCEL_ONLINE:
 526         case MEM_CANCEL_OFFLINE:
 527         default:
 528                 break;
 529         }
 530
 531         return NOTIFY_OK;
 532 }
 533 #endif  /* CONFIG_HUGETLBFS */
 534 #else   /* !CONFIG_MEMORY_HOTPLUG_SPARSE */
 535
 536 static int link_mem_sections(int nid) { return 0; }
 537 #endif  /* CONFIG_MEMORY_HOTPLUG_SPARSE */
 538
 539 #if !defined(CONFIG_MEMORY_HOTPLUG_SPARSE) || \
 540     !defined(CONFIG_HUGETLBFS)
 541 static inline int node_memory_callback(struct notifier_block *self,
 542                                 unsigned long action, void *arg)
 543 {
 544         return NOTIFY_OK;
 545 }
 546
 547 static void init_node_hugetlb_work(int nid) { }
 548
 549 #endif
 550
 551 int register_one_node(int nid)
 552 {
 553         int error = 0;
 554         int cpu;
 555
 556         if (node_online(nid)) {
 557                 int p_node = parent_node(nid);
 558                 struct node *parent = NULL;
 559
 560                 if (p_node != nid)
 561                         parent = &node_devices[p_node];
 562
 563                 error = register_node(&node_devices[nid], nid, parent);
 564
 565                 /* link cpu under this node */
 566                 for_each_present_cpu(cpu) {
 567                         if (cpu_to_node(cpu) == nid)
 568                                 register_cpu_under_node(cpu, nid);
 569                 }
 570
 571                 /* link memory sections under this node */
 572                 error = link_mem_sections(nid);
 573
 574                 /* initialize work queue for memory hot plug */
 575                 init_node_hugetlb_work(nid);
 576         }
 577
 578         return error;
 579
 580 }
 581
 582 void unregister_one_node(int nid)
 583 {
 584         unregister_node(&node_devices[nid]);
 585 }
 586
 587 /*
 588  * node states attributes
 589  */
 590
 591 static ssize_t print_nodes_state(enum node_states state, char *buf)
 592 {
 593         int n;
 594
 595         n = nodelist_scnprintf(buf, PAGE_SIZE, node_states[state]);
 596         if (n > 0 && PAGE_SIZE > n + 1) {
 597                 *(buf + n++) = '\n';
 598                 *(buf + n++) = '\0';
 599         }
 600         return n;
 601 }
 602
 603 struct node_attr {
 604         struct device_attribute attr;
 605         enum node_states state;
 606 };
 607
 608 static ssize_t show_node_state(struct device *dev,
 609                                struct device_attribute *attr, char *buf)
 610 {
 611         struct node_attr *na = container_of(attr, struct node_attr, attr);
 612         return print_nodes_state(na->state, buf);
 613 }
 614
 615 #define _NODE_ATTR(name, state) \
 616         { __ATTR(name, 0444, show_node_state, NULL), state }
 617
 618 static struct node_attr node_state_attr[] = {
 619         _NODE_ATTR(possible, N_POSSIBLE),
 620         _NODE_ATTR(online, N_ONLINE),
 621         _NODE_ATTR(has_normal_memory, N_NORMAL_MEMORY),
 622         _NODE_ATTR(has_cpu, N_CPU),
 623 #ifdef CONFIG_HIGHMEM
 624         _NODE_ATTR(has_high_memory, N_HIGH_MEMORY),
 625 #endif
 626 };
 627
 628 static struct attribute *node_state_attrs[] = {
 629         &node_state_attr[0].attr.attr,
 630         &node_state_attr[1].attr.attr,
 631         &node_state_attr[2].attr.attr,
 632         &node_state_attr[3].attr.attr,
 633 #ifdef CONFIG_HIGHMEM
 634         &node_state_attr[4].attr.attr,
 635 #endif
 636         NULL
 637 };
 638
 639 static struct attribute_group memory_root_attr_group = {
 640         .attrs = node_state_attrs,
 641 };
 642
 643 static const struct attribute_group *cpu_root_attr_groups[] = {
 644         &memory_root_attr_group,
 645         NULL,
 646 };
 647
 648 #define NODE_CALLBACK_PRI       2       /* lower than SLAB */
 649 static int __init register_node_type(void)
 650 {
 651         int ret;
 652
 653         BUILD_BUG_ON(ARRAY_SIZE(node_state_attr) != NR_NODE_STATES);
 654         BUILD_BUG_ON(ARRAY_SIZE(node_state_attrs)-1 != NR_NODE_STATES);
 655
 656         ret = subsys_system_register(&node_subsys, cpu_root_attr_groups);
 657         if (!ret) {
 658                 hotplug_memory_notifier(node_memory_callback,
 659                                         NODE_CALLBACK_PRI);
 660         }
 661
 662         /*
 663          * Note:  we're not going to unregister the node class if we fail
 664          * to register the node state class attribute files.
 665          */
 666         return ret;
 667 }
 668 postcore_initcall(register_node_type);