drivers/base/node.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Basic Node interface support
   4  */
   5
   6 #include <linux/module.h>
   7 #include <linux/init.h>
   8 #include <linux/mm.h>
   9 #include <linux/memory.h>
  10 #include <linux/vmstat.h>
  11 #include <linux/notifier.h>
  12 #include <linux/node.h>
  13 #include <linux/hugetlb.h>
  14 #include <linux/compaction.h>
  15 #include <linux/cpumask.h>
  16 #include <linux/topology.h>
  17 #include <linux/nodemask.h>
  18 #include <linux/cpu.h>
  19 #include <linux/device.h>
  20 #include <linux/swap.h>
  21 #include <linux/slab.h>
  22
  23 static struct bus_type node_subsys = {
  24         .name = "node",
  25         .dev_name = "node",
  26 };
  27
  28
  29 static ssize_t node_read_cpumap(struct device *dev, bool list, char *buf)
  30 {
  31         ssize_t n;
  32         cpumask_var_t mask;
  33         struct node *node_dev = to_node(dev);
  34
  35         /* 2008/04/07: buf currently PAGE_SIZE, need 9 chars per 32 bits. */
  36         BUILD_BUG_ON((NR_CPUS/32 * 9) > (PAGE_SIZE-1));
  37
  38         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
  39                 return 0;
  40
  41         cpumask_and(mask, cpumask_of_node(node_dev->dev.id), cpu_online_mask);
  42         n = cpumap_print_to_pagebuf(list, buf, mask);
  43         free_cpumask_var(mask);
  44
  45         return n;
  46 }
  47
  48 static inline ssize_t node_read_cpumask(struct device *dev,
  49                                 struct device_attribute *attr, char *buf)
  50 {
  51         return node_read_cpumap(dev, false, buf);
  52 }
  53 static inline ssize_t node_read_cpulist(struct device *dev,
  54                                 struct device_attribute *attr, char *buf)
  55 {
  56         return node_read_cpumap(dev, true, buf);
  57 }
  58
  59 static DEVICE_ATTR(cpumap,  S_IRUGO, node_read_cpumask, NULL);
  60 static DEVICE_ATTR(cpulist, S_IRUGO, node_read_cpulist, NULL);
  61
  62 #define K(x) ((x) << (PAGE_SHIFT - 10))
  63 static ssize_t node_read_meminfo(struct device *dev,
  64                         struct device_attribute *attr, char *buf)
  65 {
  66         int n;
  67         int nid = dev->id;
  68         struct pglist_data *pgdat = NODE_DATA(nid);
  69         struct sysinfo i;
  70
  71         si_meminfo_node(&i, nid);
  72         n = sprintf(buf,
  73                        "Node %d MemTotal:       %8lu kB\n"
  74                        "Node %d MemFree:        %8lu kB\n"
  75                        "Node %d MemUsed:        %8lu kB\n"
  76                        "Node %d Active:         %8lu kB\n"
  77                        "Node %d Inactive:       %8lu kB\n"
  78                        "Node %d Active(anon):   %8lu kB\n"
  79                        "Node %d Inactive(anon): %8lu kB\n"
  80                        "Node %d Active(file):   %8lu kB\n"
  81                        "Node %d Inactive(file): %8lu kB\n"
  82                        "Node %d Unevictable:    %8lu kB\n"
  83                        "Node %d Mlocked:        %8lu kB\n",
  84                        nid, K(i.totalram),
  85                        nid, K(i.freeram),
  86                        nid, K(i.totalram - i.freeram),
  87                        nid, K(node_page_state(pgdat, NR_ACTIVE_ANON) +
  88                                 node_page_state(pgdat, NR_ACTIVE_FILE)),
  89                        nid, K(node_page_state(pgdat, NR_INACTIVE_ANON) +
  90                                 node_page_state(pgdat, NR_INACTIVE_FILE)),
  91                        nid, K(node_page_state(pgdat, NR_ACTIVE_ANON)),
  92                        nid, K(node_page_state(pgdat, NR_INACTIVE_ANON)),
  93                        nid, K(node_page_state(pgdat, NR_ACTIVE_FILE)),
  94                        nid, K(node_page_state(pgdat, NR_INACTIVE_FILE)),
  95                        nid, K(node_page_state(pgdat, NR_UNEVICTABLE)),
  96                        nid, K(sum_zone_node_page_state(nid, NR_MLOCK)));
  97
  98 #ifdef CONFIG_HIGHMEM
  99         n += sprintf(buf + n,
 100                        "Node %d HighTotal:      %8lu kB\n"
 101                        "Node %d HighFree:       %8lu kB\n"
 102                        "Node %d LowTotal:       %8lu kB\n"
 103                        "Node %d LowFree:        %8lu kB\n",
 104                        nid, K(i.totalhigh),
 105                        nid, K(i.freehigh),
 106                        nid, K(i.totalram - i.totalhigh),
 107                        nid, K(i.freeram - i.freehigh));
 108 #endif
 109         n += sprintf(buf + n,
 110                        "Node %d Dirty:          %8lu kB\n"
 111                        "Node %d Writeback:      %8lu kB\n"
 112                        "Node %d FilePages:      %8lu kB\n"
 113                        "Node %d Mapped:         %8lu kB\n"
 114                        "Node %d AnonPages:      %8lu kB\n"
 115                        "Node %d Shmem:          %8lu kB\n"
 116                        "Node %d KernelStack:    %8lu kB\n"
 117                        "Node %d PageTables:     %8lu kB\n"
 118                        "Node %d NFS_Unstable:   %8lu kB\n"
 119                        "Node %d Bounce:         %8lu kB\n"
 120                        "Node %d WritebackTmp:   %8lu kB\n"
 121                        "Node %d Slab:           %8lu kB\n"
 122                        "Node %d SReclaimable:   %8lu kB\n"
 123                        "Node %d SUnreclaim:     %8lu kB\n"
 124 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 125                        "Node %d AnonHugePages:  %8lu kB\n"
 126                        "Node %d ShmemHugePages: %8lu kB\n"
 127                        "Node %d ShmemPmdMapped: %8lu kB\n"
 128 #endif
 129                         ,
 130                        nid, K(node_page_state(pgdat, NR_FILE_DIRTY)),
 131                        nid, K(node_page_state(pgdat, NR_WRITEBACK)),
 132                        nid, K(node_page_state(pgdat, NR_FILE_PAGES)),
 133                        nid, K(node_page_state(pgdat, NR_FILE_MAPPED)),
 134                        nid, K(node_page_state(pgdat, NR_ANON_MAPPED)),
 135                        nid, K(i.sharedram),
 136                        nid, sum_zone_node_page_state(nid, NR_KERNEL_STACK_KB),
 137                        nid, K(sum_zone_node_page_state(nid, NR_PAGETABLE)),
 138                        nid, K(node_page_state(pgdat, NR_UNSTABLE_NFS)),
 139                        nid, K(sum_zone_node_page_state(nid, NR_BOUNCE)),
 140                        nid, K(node_page_state(pgdat, NR_WRITEBACK_TEMP)),
 141                        nid, K(node_page_state(pgdat, NR_SLAB_RECLAIMABLE) +
 142                               node_page_state(pgdat, NR_SLAB_UNRECLAIMABLE)),
 143                        nid, K(node_page_state(pgdat, NR_SLAB_RECLAIMABLE)),
 144 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 145                        nid, K(node_page_state(pgdat, NR_SLAB_UNRECLAIMABLE)),
 146                        nid, K(node_page_state(pgdat, NR_ANON_THPS) *
 147                                        HPAGE_PMD_NR),
 148                        nid, K(node_page_state(pgdat, NR_SHMEM_THPS) *
 149                                        HPAGE_PMD_NR),
 150                        nid, K(node_page_state(pgdat, NR_SHMEM_PMDMAPPED) *
 151                                        HPAGE_PMD_NR));
 152 #else
 153                        nid, K(node_page_state(pgdat, NR_SLAB_UNRECLAIMABLE)));
 154 #endif
 155         n += hugetlb_report_node_meminfo(nid, buf + n);
 156         return n;
 157 }
 158
 159 #undef K
 160 static DEVICE_ATTR(meminfo, S_IRUGO, node_read_meminfo, NULL);
 161
 162 static ssize_t node_read_numastat(struct device *dev,
 163                                 struct device_attribute *attr, char *buf)
 164 {
 165         return sprintf(buf,
 166                        "numa_hit %lu\n"
 167                        "numa_miss %lu\n"
 168                        "numa_foreign %lu\n"
 169                        "interleave_hit %lu\n"
 170                        "local_node %lu\n"
 171                        "other_node %lu\n",
 172                        sum_zone_numa_state(dev->id, NUMA_HIT),
 173                        sum_zone_numa_state(dev->id, NUMA_MISS),
 174                        sum_zone_numa_state(dev->id, NUMA_FOREIGN),
 175                        sum_zone_numa_state(dev->id, NUMA_INTERLEAVE_HIT),
 176                        sum_zone_numa_state(dev->id, NUMA_LOCAL),
 177                        sum_zone_numa_state(dev->id, NUMA_OTHER));
 178 }
 179 static DEVICE_ATTR(numastat, S_IRUGO, node_read_numastat, NULL);
 180
 181 static ssize_t node_read_vmstat(struct device *dev,
 182                                 struct device_attribute *attr, char *buf)
 183 {
 184         int nid = dev->id;
 185         struct pglist_data *pgdat = NODE_DATA(nid);
 186         int i;
 187         int n = 0;
 188
 189         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 190                 n += sprintf(buf+n, "%s %lu\n", vmstat_text[i],
 191                              sum_zone_node_page_state(nid, i));
 192
 193 #ifdef CONFIG_NUMA
 194         for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
 195                 n += sprintf(buf+n, "%s %lu\n",
 196                              vmstat_text[i + NR_VM_ZONE_STAT_ITEMS],
 197                              sum_zone_numa_state(nid, i));
 198 #endif
 199
 200         for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
 201                 n += sprintf(buf+n, "%s %lu\n",
 202                              vmstat_text[i + NR_VM_ZONE_STAT_ITEMS +
 203                              NR_VM_NUMA_STAT_ITEMS],
 204                              node_page_state(pgdat, i));
 205
 206         return n;
 207 }
 208 static DEVICE_ATTR(vmstat, S_IRUGO, node_read_vmstat, NULL);
 209
 210 static ssize_t node_read_distance(struct device *dev,
 211                         struct device_attribute *attr, char *buf)
 212 {
 213         int nid = dev->id;
 214         int len = 0;
 215         int i;
 216
 217         /*
 218          * buf is currently PAGE_SIZE in length and each node needs 4 chars
 219          * at the most (distance + space or newline).
 220          */
 221         BUILD_BUG_ON(MAX_NUMNODES * 4 > PAGE_SIZE);
 222
 223         for_each_online_node(i)
 224                 len += sprintf(buf + len, "%s%d", i ? " " : "", node_distance(nid, i));
 225
 226         len += sprintf(buf + len, "\n");
 227         return len;
 228 }
 229 static DEVICE_ATTR(distance, S_IRUGO, node_read_distance, NULL);
 230
 231 static struct attribute *node_dev_attrs[] = {
 232         &dev_attr_cpumap.attr,
 233         &dev_attr_cpulist.attr,
 234         &dev_attr_meminfo.attr,
 235         &dev_attr_numastat.attr,
 236         &dev_attr_distance.attr,
 237         &dev_attr_vmstat.attr,
 238         NULL
 239 };
 240 ATTRIBUTE_GROUPS(node_dev);
 241
 242 #ifdef CONFIG_HUGETLBFS
 243 /*
 244  * hugetlbfs per node attributes registration interface:
 245  * When/if hugetlb[fs] subsystem initializes [sometime after this module],
 246  * it will register its per node attributes for all online nodes with
 247  * memory.  It will also call register_hugetlbfs_with_node(), below, to
 248  * register its attribute registration functions with this node driver.
 249  * Once these hooks have been initialized, the node driver will call into
 250  * the hugetlb module to [un]register attributes for hot-plugged nodes.
 251  */
 252 static node_registration_func_t __hugetlb_register_node;
 253 static node_registration_func_t __hugetlb_unregister_node;
 254
 255 static inline bool hugetlb_register_node(struct node *node)
 256 {
 257         if (__hugetlb_register_node &&
 258                         node_state(node->dev.id, N_MEMORY)) {
 259                 __hugetlb_register_node(node);
 260                 return true;
 261         }
 262         return false;
 263 }
 264
 265 static inline void hugetlb_unregister_node(struct node *node)
 266 {
 267         if (__hugetlb_unregister_node)
 268                 __hugetlb_unregister_node(node);
 269 }
 270
 271 void register_hugetlbfs_with_node(node_registration_func_t doregister,
 272                                   node_registration_func_t unregister)
 273 {
 274         __hugetlb_register_node   = doregister;
 275         __hugetlb_unregister_node = unregister;
 276 }
 277 #else
 278 static inline void hugetlb_register_node(struct node *node) {}
 279
 280 static inline void hugetlb_unregister_node(struct node *node) {}
 281 #endif
 282
 283 static void node_device_release(struct device *dev)
 284 {
 285         struct node *node = to_node(dev);
 286
 287 #if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) && defined(CONFIG_HUGETLBFS)
 288         /*
 289          * We schedule the work only when a memory section is
 290          * onlined/offlined on this node. When we come here,
 291          * all the memory on this node has been offlined,
 292          * so we won't enqueue new work to this work.
 293          *
 294          * The work is using node->node_work, so we should
 295          * flush work before freeing the memory.
 296          */
 297         flush_work(&node->node_work);
 298 #endif
 299         kfree(node);
 300 }
 301
 302 /*
 303  * register_node - Setup a sysfs device for a node.
 304  * @num - Node number to use when creating the device.
 305  *
 306  * Initialize and register the node device.
 307  */
 308 static int register_node(struct node *node, int num)
 309 {
 310         int error;
 311
 312         node->dev.id = num;
 313         node->dev.bus = &node_subsys;
 314         node->dev.release = node_device_release;
 315         node->dev.groups = node_dev_groups;
 316         error = device_register(&node->dev);
 317
 318         if (!error){
 319                 hugetlb_register_node(node);
 320
 321                 compaction_register_node(node);
 322         }
 323         return error;
 324 }
 325
 326 /**
 327  * unregister_node - unregister a node device
 328  * @node: node going away
 329  *
 330  * Unregisters a node device @node.  All the devices on the node must be
 331  * unregistered before calling this function.
 332  */
 333 void unregister_node(struct node *node)
 334 {
 335         hugetlb_unregister_node(node);          /* no-op, if memoryless node */
 336
 337         device_unregister(&node->dev);
 338 }
 339
 340 struct node *node_devices[MAX_NUMNODES];
 341
 342 /*
 343  * register cpu under node
 344  */
 345 int register_cpu_under_node(unsigned int cpu, unsigned int nid)
 346 {
 347         int ret;
 348         struct device *obj;
 349
 350         if (!node_online(nid))
 351                 return 0;
 352
 353         obj = get_cpu_device(cpu);
 354         if (!obj)
 355                 return 0;
 356
 357         ret = sysfs_create_link(&node_devices[nid]->dev.kobj,
 358                                 &obj->kobj,
 359                                 kobject_name(&obj->kobj));
 360         if (ret)
 361                 return ret;
 362
 363         return sysfs_create_link(&obj->kobj,
 364                                  &node_devices[nid]->dev.kobj,
 365                                  kobject_name(&node_devices[nid]->dev.kobj));
 366 }
 367
 368 int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
 369 {
 370         struct device *obj;
 371
 372         if (!node_online(nid))
 373                 return 0;
 374
 375         obj = get_cpu_device(cpu);
 376         if (!obj)
 377                 return 0;
 378
 379         sysfs_remove_link(&node_devices[nid]->dev.kobj,
 380                           kobject_name(&obj->kobj));
 381         sysfs_remove_link(&obj->kobj,
 382                           kobject_name(&node_devices[nid]->dev.kobj));
 383
 384         return 0;
 385 }
 386
 387 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
 388 static int __ref get_nid_for_pfn(unsigned long pfn)
 389 {
 390         if (!pfn_valid_within(pfn))
 391                 return -1;
 392 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
 393         if (system_state < SYSTEM_RUNNING)
 394                 return early_pfn_to_nid(pfn);
 395 #endif
 396         return pfn_to_nid(pfn);
 397 }
 398
 399 /* register memory section under specified node if it spans that node */
 400 int register_mem_sect_under_node(struct memory_block *mem_blk, int nid)
 401 {
 402         int ret;
 403         unsigned long pfn, sect_start_pfn, sect_end_pfn;
 404
 405         if (!mem_blk)
 406                 return -EFAULT;
 407         if (!node_online(nid))
 408                 return 0;
 409
 410         sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
 411         sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr);
 412         sect_end_pfn += PAGES_PER_SECTION - 1;
 413         for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
 414                 int page_nid;
 415
 416                 /*
 417                  * memory block could have several absent sections from start.
 418                  * skip pfn range from absent section
 419                  */
 420                 if (!pfn_present(pfn)) {
 421                         pfn = round_down(pfn + PAGES_PER_SECTION,
 422                                          PAGES_PER_SECTION) - 1;
 423                         continue;
 424                 }
 425
 426                 page_nid = get_nid_for_pfn(pfn);
 427                 if (page_nid < 0)
 428                         continue;
 429                 if (page_nid != nid)
 430                         continue;
 431                 ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj,
 432                                         &mem_blk->dev.kobj,
 433                                         kobject_name(&mem_blk->dev.kobj));
 434                 if (ret)
 435                         return ret;
 436
 437                 return sysfs_create_link_nowarn(&mem_blk->dev.kobj,
 438                                 &node_devices[nid]->dev.kobj,
 439                                 kobject_name(&node_devices[nid]->dev.kobj));
 440         }
 441         /* mem section does not span the specified node */
 442         return 0;
 443 }
 444
 445 /* unregister memory section under all nodes that it spans */
 446 int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
 447                                     unsigned long phys_index)
 448 {
 449         NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
 450         unsigned long pfn, sect_start_pfn, sect_end_pfn;
 451
 452         if (!mem_blk) {
 453                 NODEMASK_FREE(unlinked_nodes);
 454                 return -EFAULT;
 455         }
 456         if (!unlinked_nodes)
 457                 return -ENOMEM;
 458         nodes_clear(*unlinked_nodes);
 459
 460         sect_start_pfn = section_nr_to_pfn(phys_index);
 461         sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
 462         for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
 463                 int nid;
 464
 465                 nid = get_nid_for_pfn(pfn);
 466                 if (nid < 0)
 467                         continue;
 468                 if (!node_online(nid))
 469                         continue;
 470                 if (node_test_and_set(nid, *unlinked_nodes))
 471                         continue;
 472                 sysfs_remove_link(&node_devices[nid]->dev.kobj,
 473                          kobject_name(&mem_blk->dev.kobj));
 474                 sysfs_remove_link(&mem_blk->dev.kobj,
 475                          kobject_name(&node_devices[nid]->dev.kobj));
 476         }
 477         NODEMASK_FREE(unlinked_nodes);
 478         return 0;
 479 }
 480
 481 int link_mem_sections(int nid, unsigned long start_pfn, unsigned long nr_pages)
 482 {
 483         unsigned long end_pfn = start_pfn + nr_pages;
 484         unsigned long pfn;
 485         struct memory_block *mem_blk = NULL;
 486         int err = 0;
 487
 488         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 489                 unsigned long section_nr = pfn_to_section_nr(pfn);
 490                 struct mem_section *mem_sect;
 491                 int ret;
 492
 493                 if (!present_section_nr(section_nr))
 494                         continue;
 495                 mem_sect = __nr_to_section(section_nr);
 496
 497                 /* same memblock ? */
 498                 if (mem_blk)
 499                         if ((section_nr >= mem_blk->start_section_nr) &&
 500                             (section_nr <= mem_blk->end_section_nr))
 501                                 continue;
 502
 503                 mem_blk = find_memory_block_hinted(mem_sect, mem_blk);
 504
 505                 ret = register_mem_sect_under_node(mem_blk, nid);
 506                 if (!err)
 507                         err = ret;
 508
 509                 /* discard ref obtained in find_memory_block() */
 510         }
 511
 512         if (mem_blk)
 513                 kobject_put(&mem_blk->dev.kobj);
 514         return err;
 515 }
 516
 517 #ifdef CONFIG_HUGETLBFS
 518 /*
 519  * Handle per node hstate attribute [un]registration on transistions
 520  * to/from memoryless state.
 521  */
 522 static void node_hugetlb_work(struct work_struct *work)
 523 {
 524         struct node *node = container_of(work, struct node, node_work);
 525
 526         /*
 527          * We only get here when a node transitions to/from memoryless state.
 528          * We can detect which transition occurred by examining whether the
 529          * node has memory now.  hugetlb_register_node() already check this
 530          * so we try to register the attributes.  If that fails, then the
 531          * node has transitioned to memoryless, try to unregister the
 532          * attributes.
 533          */
 534         if (!hugetlb_register_node(node))
 535                 hugetlb_unregister_node(node);
 536 }
 537
 538 static void init_node_hugetlb_work(int nid)
 539 {
 540         INIT_WORK(&node_devices[nid]->node_work, node_hugetlb_work);
 541 }
 542
 543 static int node_memory_callback(struct notifier_block *self,
 544                                 unsigned long action, void *arg)
 545 {
 546         struct memory_notify *mnb = arg;
 547         int nid = mnb->status_change_nid;
 548
 549         switch (action) {
 550         case MEM_ONLINE:
 551         case MEM_OFFLINE:
 552                 /*
 553                  * offload per node hstate [un]registration to a work thread
 554                  * when transitioning to/from memoryless state.
 555                  */
 556                 if (nid != NUMA_NO_NODE)
 557                         schedule_work(&node_devices[nid]->node_work);
 558                 break;
 559
 560         case MEM_GOING_ONLINE:
 561         case MEM_GOING_OFFLINE:
 562         case MEM_CANCEL_ONLINE:
 563         case MEM_CANCEL_OFFLINE:
 564         default:
 565                 break;
 566         }
 567
 568         return NOTIFY_OK;
 569 }
 570 #endif  /* CONFIG_HUGETLBFS */
 571 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
 572
 573 #if !defined(CONFIG_MEMORY_HOTPLUG_SPARSE) || \
 574     !defined(CONFIG_HUGETLBFS)
 575 static inline int node_memory_callback(struct notifier_block *self,
 576                                 unsigned long action, void *arg)
 577 {
 578         return NOTIFY_OK;
 579 }
 580
 581 static void init_node_hugetlb_work(int nid) { }
 582
 583 #endif
 584
 585 int __register_one_node(int nid)
 586 {
 587         int error;
 588         int cpu;
 589
 590         node_devices[nid] = kzalloc(sizeof(struct node), GFP_KERNEL);
 591         if (!node_devices[nid])
 592                 return -ENOMEM;
 593
 594         error = register_node(node_devices[nid], nid);
 595
 596         /* link cpu under this node */
 597         for_each_present_cpu(cpu) {
 598                 if (cpu_to_node(cpu) == nid)
 599                         register_cpu_under_node(cpu, nid);
 600         }
 601
 602         /* initialize work queue for memory hot plug */
 603         init_node_hugetlb_work(nid);
 604
 605         return error;
 606 }
 607
 608 void unregister_one_node(int nid)
 609 {
 610         if (!node_devices[nid])
 611                 return;
 612
 613         unregister_node(node_devices[nid]);
 614         node_devices[nid] = NULL;
 615 }
 616
 617 /*
 618  * node states attributes
 619  */
 620
 621 static ssize_t print_nodes_state(enum node_states state, char *buf)
 622 {
 623         int n;
 624
 625         n = scnprintf(buf, PAGE_SIZE - 1, "%*pbl",
 626                       nodemask_pr_args(&node_states[state]));
 627         buf[n++] = '\n';
 628         buf[n] = '\0';
 629         return n;
 630 }
 631
 632 struct node_attr {
 633         struct device_attribute attr;
 634         enum node_states state;
 635 };
 636
 637 static ssize_t show_node_state(struct device *dev,
 638                                struct device_attribute *attr, char *buf)
 639 {
 640         struct node_attr *na = container_of(attr, struct node_attr, attr);
 641         return print_nodes_state(na->state, buf);
 642 }
 643
 644 #define _NODE_ATTR(name, state) \
 645         { __ATTR(name, 0444, show_node_state, NULL), state }
 646
 647 static struct node_attr node_state_attr[] = {
 648         [N_POSSIBLE] = _NODE_ATTR(possible, N_POSSIBLE),
 649         [N_ONLINE] = _NODE_ATTR(online, N_ONLINE),
 650         [N_NORMAL_MEMORY] = _NODE_ATTR(has_normal_memory, N_NORMAL_MEMORY),
 651 #ifdef CONFIG_HIGHMEM
 652         [N_HIGH_MEMORY] = _NODE_ATTR(has_high_memory, N_HIGH_MEMORY),
 653 #endif
 654         [N_MEMORY] = _NODE_ATTR(has_memory, N_MEMORY),
 655         [N_CPU] = _NODE_ATTR(has_cpu, N_CPU),
 656 };
 657
 658 static struct attribute *node_state_attrs[] = {
 659         &node_state_attr[N_POSSIBLE].attr.attr,
 660         &node_state_attr[N_ONLINE].attr.attr,
 661         &node_state_attr[N_NORMAL_MEMORY].attr.attr,
 662 #ifdef CONFIG_HIGHMEM
 663         &node_state_attr[N_HIGH_MEMORY].attr.attr,
 664 #endif
 665         &node_state_attr[N_MEMORY].attr.attr,
 666         &node_state_attr[N_CPU].attr.attr,
 667         NULL
 668 };
 669
 670 static struct attribute_group memory_root_attr_group = {
 671         .attrs = node_state_attrs,
 672 };
 673
 674 static const struct attribute_group *cpu_root_attr_groups[] = {
 675         &memory_root_attr_group,
 676         NULL,
 677 };
 678
 679 #define NODE_CALLBACK_PRI       2       /* lower than SLAB */
 680 static int __init register_node_type(void)
 681 {
 682         int ret;
 683
 684         BUILD_BUG_ON(ARRAY_SIZE(node_state_attr) != NR_NODE_STATES);
 685         BUILD_BUG_ON(ARRAY_SIZE(node_state_attrs)-1 != NR_NODE_STATES);
 686
 687         ret = subsys_system_register(&node_subsys, cpu_root_attr_groups);
 688         if (!ret) {
 689                 static struct notifier_block node_memory_callback_nb = {
 690                         .notifier_call = node_memory_callback,
 691                         .priority = NODE_CALLBACK_PRI,
 692                 };
 693                 register_hotmemory_notifier(&node_memory_callback_nb);
 694         }
 695
 696         /*
 697          * Note:  we're not going to unregister the node class if we fail
 698          * to register the node state class attribute files.
 699          */
 700         return ret;
 701 }
 702 postcore_initcall(register_node_type);