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/notifier.h> 11 #include <linux/node.h> 12 #include <linux/hugetlb.h> 13 #include <linux/compaction.h> 14 #include <linux/cpumask.h> 15 #include <linux/topology.h> 16 #include <linux/nodemask.h> 17 #include <linux/cpu.h> 18 #include <linux/device.h> 19 #include <linux/swap.h> 20 #include <linux/slab.h> 21 22 static struct bus_type node_subsys = { 23 .name = "node", 24 .dev_name = "node", 25 }; 26 27 28 static ssize_t node_read_cpumap(struct device *dev, bool list, char *buf) 29 { 30 struct node *node_dev = to_node(dev); 31 const struct cpumask *mask = cpumask_of_node(node_dev->dev.id); 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 return cpumap_print_to_pagebuf(list, buf, mask); 37 } 38 39 static inline ssize_t node_read_cpumask(struct device *dev, 40 struct device_attribute *attr, char *buf) 41 { 42 return node_read_cpumap(dev, false, buf); 43 } 44 static inline ssize_t node_read_cpulist(struct device *dev, 45 struct device_attribute *attr, char *buf) 46 { 47 return node_read_cpumap(dev, true, buf); 48 } 49 50 static DEVICE_ATTR(cpumap, S_IRUGO, node_read_cpumask, NULL); 51 static DEVICE_ATTR(cpulist, S_IRUGO, node_read_cpulist, NULL); 52 53 #define K(x) ((x) << (PAGE_SHIFT - 10)) 54 static ssize_t node_read_meminfo(struct device *dev, 55 struct device_attribute *attr, char *buf) 56 { 57 int n; 58 int nid = dev->id; 59 struct sysinfo i; 60 61 si_meminfo_node(&i, nid); 62 n = sprintf(buf, 63 "Node %d MemTotal: %8lu kB\n" 64 "Node %d MemFree: %8lu kB\n" 65 "Node %d MemUsed: %8lu kB\n" 66 "Node %d Active: %8lu kB\n" 67 "Node %d Inactive: %8lu kB\n" 68 "Node %d Active(anon): %8lu kB\n" 69 "Node %d Inactive(anon): %8lu kB\n" 70 "Node %d Active(file): %8lu kB\n" 71 "Node %d Inactive(file): %8lu kB\n" 72 "Node %d Unevictable: %8lu kB\n" 73 "Node %d Mlocked: %8lu kB\n", 74 nid, K(i.totalram), 75 nid, K(i.freeram), 76 nid, K(i.totalram - i.freeram), 77 nid, K(node_page_state(nid, NR_ACTIVE_ANON) + 78 node_page_state(nid, NR_ACTIVE_FILE)), 79 nid, K(node_page_state(nid, NR_INACTIVE_ANON) + 80 node_page_state(nid, NR_INACTIVE_FILE)), 81 nid, K(node_page_state(nid, NR_ACTIVE_ANON)), 82 nid, K(node_page_state(nid, NR_INACTIVE_ANON)), 83 nid, K(node_page_state(nid, NR_ACTIVE_FILE)), 84 nid, K(node_page_state(nid, NR_INACTIVE_FILE)), 85 nid, K(node_page_state(nid, NR_UNEVICTABLE)), 86 nid, K(node_page_state(nid, NR_MLOCK))); 87 88 #ifdef CONFIG_HIGHMEM 89 n += sprintf(buf + n, 90 "Node %d HighTotal: %8lu kB\n" 91 "Node %d HighFree: %8lu kB\n" 92 "Node %d LowTotal: %8lu kB\n" 93 "Node %d LowFree: %8lu kB\n", 94 nid, K(i.totalhigh), 95 nid, K(i.freehigh), 96 nid, K(i.totalram - i.totalhigh), 97 nid, K(i.freeram - i.freehigh)); 98 #endif 99 n += sprintf(buf + n, 100 "Node %d Dirty: %8lu kB\n" 101 "Node %d Writeback: %8lu kB\n" 102 "Node %d FilePages: %8lu kB\n" 103 "Node %d Mapped: %8lu kB\n" 104 "Node %d AnonPages: %8lu kB\n" 105 "Node %d Shmem: %8lu kB\n" 106 "Node %d KernelStack: %8lu kB\n" 107 "Node %d PageTables: %8lu kB\n" 108 "Node %d NFS_Unstable: %8lu kB\n" 109 "Node %d Bounce: %8lu kB\n" 110 "Node %d WritebackTmp: %8lu kB\n" 111 "Node %d Slab: %8lu kB\n" 112 "Node %d SReclaimable: %8lu kB\n" 113 "Node %d SUnreclaim: %8lu kB\n" 114 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 115 "Node %d AnonHugePages: %8lu kB\n" 116 #endif 117 , 118 nid, K(node_page_state(nid, NR_FILE_DIRTY)), 119 nid, K(node_page_state(nid, NR_WRITEBACK)), 120 nid, K(node_page_state(nid, NR_FILE_PAGES)), 121 nid, K(node_page_state(nid, NR_FILE_MAPPED)), 122 nid, K(node_page_state(nid, NR_ANON_PAGES)), 123 nid, K(i.sharedram), 124 nid, node_page_state(nid, NR_KERNEL_STACK) * 125 THREAD_SIZE / 1024, 126 nid, K(node_page_state(nid, NR_PAGETABLE)), 127 nid, K(node_page_state(nid, NR_UNSTABLE_NFS)), 128 nid, K(node_page_state(nid, NR_BOUNCE)), 129 nid, K(node_page_state(nid, NR_WRITEBACK_TEMP)), 130 nid, K(node_page_state(nid, NR_SLAB_RECLAIMABLE) + 131 node_page_state(nid, NR_SLAB_UNRECLAIMABLE)), 132 nid, K(node_page_state(nid, NR_SLAB_RECLAIMABLE)), 133 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 134 nid, K(node_page_state(nid, NR_SLAB_UNRECLAIMABLE)) 135 , nid, 136 K(node_page_state(nid, NR_ANON_TRANSPARENT_HUGEPAGES) * 137 HPAGE_PMD_NR)); 138 #else 139 nid, K(node_page_state(nid, NR_SLAB_UNRECLAIMABLE))); 140 #endif 141 n += hugetlb_report_node_meminfo(nid, buf + n); 142 return n; 143 } 144 145 #undef K 146 static DEVICE_ATTR(meminfo, S_IRUGO, node_read_meminfo, NULL); 147 148 static ssize_t node_read_numastat(struct device *dev, 149 struct device_attribute *attr, char *buf) 150 { 151 return sprintf(buf, 152 "numa_hit %lu\n" 153 "numa_miss %lu\n" 154 "numa_foreign %lu\n" 155 "interleave_hit %lu\n" 156 "local_node %lu\n" 157 "other_node %lu\n", 158 node_page_state(dev->id, NUMA_HIT), 159 node_page_state(dev->id, NUMA_MISS), 160 node_page_state(dev->id, NUMA_FOREIGN), 161 node_page_state(dev->id, NUMA_INTERLEAVE_HIT), 162 node_page_state(dev->id, NUMA_LOCAL), 163 node_page_state(dev->id, NUMA_OTHER)); 164 } 165 static DEVICE_ATTR(numastat, S_IRUGO, node_read_numastat, NULL); 166 167 static ssize_t node_read_vmstat(struct device *dev, 168 struct device_attribute *attr, char *buf) 169 { 170 int nid = dev->id; 171 int i; 172 int n = 0; 173 174 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) 175 n += sprintf(buf+n, "%s %lu\n", vmstat_text[i], 176 node_page_state(nid, i)); 177 178 return n; 179 } 180 static DEVICE_ATTR(vmstat, S_IRUGO, node_read_vmstat, NULL); 181 182 static ssize_t node_read_distance(struct device *dev, 183 struct device_attribute *attr, char * buf) 184 { 185 int nid = dev->id; 186 int len = 0; 187 int i; 188 189 /* 190 * buf is currently PAGE_SIZE in length and each node needs 4 chars 191 * at the most (distance + space or newline). 192 */ 193 BUILD_BUG_ON(MAX_NUMNODES * 4 > PAGE_SIZE); 194 195 for_each_online_node(i) 196 len += sprintf(buf + len, "%s%d", i ? " " : "", node_distance(nid, i)); 197 198 len += sprintf(buf + len, "\n"); 199 return len; 200 } 201 static DEVICE_ATTR(distance, S_IRUGO, node_read_distance, NULL); 202 203 #ifdef CONFIG_HUGETLBFS 204 /* 205 * hugetlbfs per node attributes registration interface: 206 * When/if hugetlb[fs] subsystem initializes [sometime after this module], 207 * it will register its per node attributes for all online nodes with 208 * memory. It will also call register_hugetlbfs_with_node(), below, to 209 * register its attribute registration functions with this node driver. 210 * Once these hooks have been initialized, the node driver will call into 211 * the hugetlb module to [un]register attributes for hot-plugged nodes. 212 */ 213 static node_registration_func_t __hugetlb_register_node; 214 static node_registration_func_t __hugetlb_unregister_node; 215 216 static inline bool hugetlb_register_node(struct node *node) 217 { 218 if (__hugetlb_register_node && 219 node_state(node->dev.id, N_MEMORY)) { 220 __hugetlb_register_node(node); 221 return true; 222 } 223 return false; 224 } 225 226 static inline void hugetlb_unregister_node(struct node *node) 227 { 228 if (__hugetlb_unregister_node) 229 __hugetlb_unregister_node(node); 230 } 231 232 void register_hugetlbfs_with_node(node_registration_func_t doregister, 233 node_registration_func_t unregister) 234 { 235 __hugetlb_register_node = doregister; 236 __hugetlb_unregister_node = unregister; 237 } 238 #else 239 static inline void hugetlb_register_node(struct node *node) {} 240 241 static inline void hugetlb_unregister_node(struct node *node) {} 242 #endif 243 244 static void node_device_release(struct device *dev) 245 { 246 struct node *node = to_node(dev); 247 248 #if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) && defined(CONFIG_HUGETLBFS) 249 /* 250 * We schedule the work only when a memory section is 251 * onlined/offlined on this node. When we come here, 252 * all the memory on this node has been offlined, 253 * so we won't enqueue new work to this work. 254 * 255 * The work is using node->node_work, so we should 256 * flush work before freeing the memory. 257 */ 258 flush_work(&node->node_work); 259 #endif 260 kfree(node); 261 } 262 263 /* 264 * register_node - Setup a sysfs device for a node. 265 * @num - Node number to use when creating the device. 266 * 267 * Initialize and register the node device. 268 */ 269 static int register_node(struct node *node, int num, struct node *parent) 270 { 271 int error; 272 273 node->dev.id = num; 274 node->dev.bus = &node_subsys; 275 node->dev.release = node_device_release; 276 error = device_register(&node->dev); 277 278 if (!error){ 279 device_create_file(&node->dev, &dev_attr_cpumap); 280 device_create_file(&node->dev, &dev_attr_cpulist); 281 device_create_file(&node->dev, &dev_attr_meminfo); 282 device_create_file(&node->dev, &dev_attr_numastat); 283 device_create_file(&node->dev, &dev_attr_distance); 284 device_create_file(&node->dev, &dev_attr_vmstat); 285 286 hugetlb_register_node(node); 287 288 compaction_register_node(node); 289 } 290 return error; 291 } 292 293 /** 294 * unregister_node - unregister a node device 295 * @node: node going away 296 * 297 * Unregisters a node device @node. All the devices on the node must be 298 * unregistered before calling this function. 299 */ 300 void unregister_node(struct node *node) 301 { 302 device_remove_file(&node->dev, &dev_attr_cpumap); 303 device_remove_file(&node->dev, &dev_attr_cpulist); 304 device_remove_file(&node->dev, &dev_attr_meminfo); 305 device_remove_file(&node->dev, &dev_attr_numastat); 306 device_remove_file(&node->dev, &dev_attr_distance); 307 device_remove_file(&node->dev, &dev_attr_vmstat); 308 309 hugetlb_unregister_node(node); /* no-op, if memoryless node */ 310 311 device_unregister(&node->dev); 312 } 313 314 struct node *node_devices[MAX_NUMNODES]; 315 316 /* 317 * register cpu under node 318 */ 319 int register_cpu_under_node(unsigned int cpu, unsigned int nid) 320 { 321 int ret; 322 struct device *obj; 323 324 if (!node_online(nid)) 325 return 0; 326 327 obj = get_cpu_device(cpu); 328 if (!obj) 329 return 0; 330 331 ret = sysfs_create_link(&node_devices[nid]->dev.kobj, 332 &obj->kobj, 333 kobject_name(&obj->kobj)); 334 if (ret) 335 return ret; 336 337 return sysfs_create_link(&obj->kobj, 338 &node_devices[nid]->dev.kobj, 339 kobject_name(&node_devices[nid]->dev.kobj)); 340 } 341 342 int unregister_cpu_under_node(unsigned int cpu, unsigned int nid) 343 { 344 struct device *obj; 345 346 if (!node_online(nid)) 347 return 0; 348 349 obj = get_cpu_device(cpu); 350 if (!obj) 351 return 0; 352 353 sysfs_remove_link(&node_devices[nid]->dev.kobj, 354 kobject_name(&obj->kobj)); 355 sysfs_remove_link(&obj->kobj, 356 kobject_name(&node_devices[nid]->dev.kobj)); 357 358 return 0; 359 } 360 361 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE 362 #define page_initialized(page) (page->lru.next) 363 364 static int get_nid_for_pfn(unsigned long pfn) 365 { 366 struct page *page; 367 368 if (!pfn_valid_within(pfn)) 369 return -1; 370 page = pfn_to_page(pfn); 371 if (!page_initialized(page)) 372 return -1; 373 return pfn_to_nid(pfn); 374 } 375 376 /* register memory section under specified node if it spans that node */ 377 int register_mem_sect_under_node(struct memory_block *mem_blk, int nid) 378 { 379 int ret; 380 unsigned long pfn, sect_start_pfn, sect_end_pfn; 381 382 if (!mem_blk) 383 return -EFAULT; 384 if (!node_online(nid)) 385 return 0; 386 387 sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr); 388 sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr); 389 sect_end_pfn += PAGES_PER_SECTION - 1; 390 for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) { 391 int page_nid; 392 393 page_nid = get_nid_for_pfn(pfn); 394 if (page_nid < 0) 395 continue; 396 if (page_nid != nid) 397 continue; 398 ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj, 399 &mem_blk->dev.kobj, 400 kobject_name(&mem_blk->dev.kobj)); 401 if (ret) 402 return ret; 403 404 return sysfs_create_link_nowarn(&mem_blk->dev.kobj, 405 &node_devices[nid]->dev.kobj, 406 kobject_name(&node_devices[nid]->dev.kobj)); 407 } 408 /* mem section does not span the specified node */ 409 return 0; 410 } 411 412 /* unregister memory section under all nodes that it spans */ 413 int unregister_mem_sect_under_nodes(struct memory_block *mem_blk, 414 unsigned long phys_index) 415 { 416 NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL); 417 unsigned long pfn, sect_start_pfn, sect_end_pfn; 418 419 if (!mem_blk) { 420 NODEMASK_FREE(unlinked_nodes); 421 return -EFAULT; 422 } 423 if (!unlinked_nodes) 424 return -ENOMEM; 425 nodes_clear(*unlinked_nodes); 426 427 sect_start_pfn = section_nr_to_pfn(phys_index); 428 sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1; 429 for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) { 430 int nid; 431 432 nid = get_nid_for_pfn(pfn); 433 if (nid < 0) 434 continue; 435 if (!node_online(nid)) 436 continue; 437 if (node_test_and_set(nid, *unlinked_nodes)) 438 continue; 439 sysfs_remove_link(&node_devices[nid]->dev.kobj, 440 kobject_name(&mem_blk->dev.kobj)); 441 sysfs_remove_link(&mem_blk->dev.kobj, 442 kobject_name(&node_devices[nid]->dev.kobj)); 443 } 444 NODEMASK_FREE(unlinked_nodes); 445 return 0; 446 } 447 448 static int link_mem_sections(int nid) 449 { 450 unsigned long start_pfn = NODE_DATA(nid)->node_start_pfn; 451 unsigned long end_pfn = start_pfn + NODE_DATA(nid)->node_spanned_pages; 452 unsigned long pfn; 453 struct memory_block *mem_blk = NULL; 454 int err = 0; 455 456 for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) { 457 unsigned long section_nr = pfn_to_section_nr(pfn); 458 struct mem_section *mem_sect; 459 int ret; 460 461 if (!present_section_nr(section_nr)) 462 continue; 463 mem_sect = __nr_to_section(section_nr); 464 465 /* same memblock ? */ 466 if (mem_blk) 467 if ((section_nr >= mem_blk->start_section_nr) && 468 (section_nr <= mem_blk->end_section_nr)) 469 continue; 470 471 mem_blk = find_memory_block_hinted(mem_sect, mem_blk); 472 473 ret = register_mem_sect_under_node(mem_blk, nid); 474 if (!err) 475 err = ret; 476 477 /* discard ref obtained in find_memory_block() */ 478 } 479 480 if (mem_blk) 481 kobject_put(&mem_blk->dev.kobj); 482 return err; 483 } 484 485 #ifdef CONFIG_HUGETLBFS 486 /* 487 * Handle per node hstate attribute [un]registration on transistions 488 * to/from memoryless state. 489 */ 490 static void node_hugetlb_work(struct work_struct *work) 491 { 492 struct node *node = container_of(work, struct node, node_work); 493 494 /* 495 * We only get here when a node transitions to/from memoryless state. 496 * We can detect which transition occurred by examining whether the 497 * node has memory now. hugetlb_register_node() already check this 498 * so we try to register the attributes. If that fails, then the 499 * node has transitioned to memoryless, try to unregister the 500 * attributes. 501 */ 502 if (!hugetlb_register_node(node)) 503 hugetlb_unregister_node(node); 504 } 505 506 static void init_node_hugetlb_work(int nid) 507 { 508 INIT_WORK(&node_devices[nid]->node_work, node_hugetlb_work); 509 } 510 511 static int node_memory_callback(struct notifier_block *self, 512 unsigned long action, void *arg) 513 { 514 struct memory_notify *mnb = arg; 515 int nid = mnb->status_change_nid; 516 517 switch (action) { 518 case MEM_ONLINE: 519 case MEM_OFFLINE: 520 /* 521 * offload per node hstate [un]registration to a work thread 522 * when transitioning to/from memoryless state. 523 */ 524 if (nid != NUMA_NO_NODE) 525 schedule_work(&node_devices[nid]->node_work); 526 break; 527 528 case MEM_GOING_ONLINE: 529 case MEM_GOING_OFFLINE: 530 case MEM_CANCEL_ONLINE: 531 case MEM_CANCEL_OFFLINE: 532 default: 533 break; 534 } 535 536 return NOTIFY_OK; 537 } 538 #endif /* CONFIG_HUGETLBFS */ 539 #else /* !CONFIG_MEMORY_HOTPLUG_SPARSE */ 540 541 static int link_mem_sections(int nid) { return 0; } 542 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */ 543 544 #if !defined(CONFIG_MEMORY_HOTPLUG_SPARSE) || \ 545 !defined(CONFIG_HUGETLBFS) 546 static inline int node_memory_callback(struct notifier_block *self, 547 unsigned long action, void *arg) 548 { 549 return NOTIFY_OK; 550 } 551 552 static void init_node_hugetlb_work(int nid) { } 553 554 #endif 555 556 int register_one_node(int nid) 557 { 558 int error = 0; 559 int cpu; 560 561 if (node_online(nid)) { 562 int p_node = parent_node(nid); 563 struct node *parent = NULL; 564 565 if (p_node != nid) 566 parent = node_devices[p_node]; 567 568 node_devices[nid] = kzalloc(sizeof(struct node), GFP_KERNEL); 569 if (!node_devices[nid]) 570 return -ENOMEM; 571 572 error = register_node(node_devices[nid], nid, parent); 573 574 /* link cpu under this node */ 575 for_each_present_cpu(cpu) { 576 if (cpu_to_node(cpu) == nid) 577 register_cpu_under_node(cpu, nid); 578 } 579 580 /* link memory sections under this node */ 581 error = link_mem_sections(nid); 582 583 /* initialize work queue for memory hot plug */ 584 init_node_hugetlb_work(nid); 585 } 586 587 return error; 588 589 } 590 591 void unregister_one_node(int nid) 592 { 593 if (!node_devices[nid]) 594 return; 595 596 unregister_node(node_devices[nid]); 597 node_devices[nid] = NULL; 598 } 599 600 /* 601 * node states attributes 602 */ 603 604 static ssize_t print_nodes_state(enum node_states state, char *buf) 605 { 606 int n; 607 608 n = scnprintf(buf, PAGE_SIZE - 1, "%*pbl", 609 nodemask_pr_args(&node_states[state])); 610 buf[n++] = '\n'; 611 buf[n] = '\0'; 612 return n; 613 } 614 615 struct node_attr { 616 struct device_attribute attr; 617 enum node_states state; 618 }; 619 620 static ssize_t show_node_state(struct device *dev, 621 struct device_attribute *attr, char *buf) 622 { 623 struct node_attr *na = container_of(attr, struct node_attr, attr); 624 return print_nodes_state(na->state, buf); 625 } 626 627 #define _NODE_ATTR(name, state) \ 628 { __ATTR(name, 0444, show_node_state, NULL), state } 629 630 static struct node_attr node_state_attr[] = { 631 [N_POSSIBLE] = _NODE_ATTR(possible, N_POSSIBLE), 632 [N_ONLINE] = _NODE_ATTR(online, N_ONLINE), 633 [N_NORMAL_MEMORY] = _NODE_ATTR(has_normal_memory, N_NORMAL_MEMORY), 634 #ifdef CONFIG_HIGHMEM 635 [N_HIGH_MEMORY] = _NODE_ATTR(has_high_memory, N_HIGH_MEMORY), 636 #endif 637 #ifdef CONFIG_MOVABLE_NODE 638 [N_MEMORY] = _NODE_ATTR(has_memory, N_MEMORY), 639 #endif 640 [N_CPU] = _NODE_ATTR(has_cpu, N_CPU), 641 }; 642 643 static struct attribute *node_state_attrs[] = { 644 &node_state_attr[N_POSSIBLE].attr.attr, 645 &node_state_attr[N_ONLINE].attr.attr, 646 &node_state_attr[N_NORMAL_MEMORY].attr.attr, 647 #ifdef CONFIG_HIGHMEM 648 &node_state_attr[N_HIGH_MEMORY].attr.attr, 649 #endif 650 #ifdef CONFIG_MOVABLE_NODE 651 &node_state_attr[N_MEMORY].attr.attr, 652 #endif 653 &node_state_attr[N_CPU].attr.attr, 654 NULL 655 }; 656 657 static struct attribute_group memory_root_attr_group = { 658 .attrs = node_state_attrs, 659 }; 660 661 static const struct attribute_group *cpu_root_attr_groups[] = { 662 &memory_root_attr_group, 663 NULL, 664 }; 665 666 #define NODE_CALLBACK_PRI 2 /* lower than SLAB */ 667 static int __init register_node_type(void) 668 { 669 int ret; 670 671 BUILD_BUG_ON(ARRAY_SIZE(node_state_attr) != NR_NODE_STATES); 672 BUILD_BUG_ON(ARRAY_SIZE(node_state_attrs)-1 != NR_NODE_STATES); 673 674 ret = subsys_system_register(&node_subsys, cpu_root_attr_groups); 675 if (!ret) { 676 static struct notifier_block node_memory_callback_nb = { 677 .notifier_call = node_memory_callback, 678 .priority = NODE_CALLBACK_PRI, 679 }; 680 register_hotmemory_notifier(&node_memory_callback_nb); 681 } 682 683 /* 684 * Note: we're not going to unregister the node class if we fail 685 * to register the node state class attribute files. 686 */ 687 return ret; 688 } 689 postcore_initcall(register_node_type); 690