xref: /linux/drivers/base/node.c (revision 8ec3b8432e4fe8d452f88f1ed9a3450e715bb797)
1 /*
2  * drivers/base/node.c - basic Node class support
3  */
4 
5 #include <linux/sysdev.h>
6 #include <linux/module.h>
7 #include <linux/init.h>
8 #include <linux/mm.h>
9 #include <linux/memory.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 sysdev_class_attribute *node_state_attrs[];
22 
23 static struct sysdev_class node_class = {
24 	.name = "node",
25 	.attrs = node_state_attrs,
26 };
27 
28 
29 static ssize_t node_read_cpumap(struct sys_device *dev, int type, char *buf)
30 {
31 	struct node *node_dev = to_node(dev);
32 	const struct cpumask *mask = cpumask_of_node(node_dev->sysdev.id);
33 	int len;
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 	len = type?
39 		cpulist_scnprintf(buf, PAGE_SIZE-2, mask) :
40 		cpumask_scnprintf(buf, PAGE_SIZE-2, mask);
41  	buf[len++] = '\n';
42  	buf[len] = '\0';
43 	return len;
44 }
45 
46 static inline ssize_t node_read_cpumask(struct sys_device *dev,
47 				struct sysdev_attribute *attr, char *buf)
48 {
49 	return node_read_cpumap(dev, 0, buf);
50 }
51 static inline ssize_t node_read_cpulist(struct sys_device *dev,
52 				struct sysdev_attribute *attr, char *buf)
53 {
54 	return node_read_cpumap(dev, 1, buf);
55 }
56 
57 static SYSDEV_ATTR(cpumap,  S_IRUGO, node_read_cpumask, NULL);
58 static SYSDEV_ATTR(cpulist, S_IRUGO, node_read_cpulist, NULL);
59 
60 #define K(x) ((x) << (PAGE_SHIFT - 10))
61 static ssize_t node_read_meminfo(struct sys_device * dev,
62 			struct sysdev_attribute *attr, char * buf)
63 {
64 	int n;
65 	int nid = dev->id;
66 	struct sysinfo i;
67 
68 	si_meminfo_node(&i, nid);
69 	n = sprintf(buf,
70 		       "Node %d MemTotal:       %8lu kB\n"
71 		       "Node %d MemFree:        %8lu kB\n"
72 		       "Node %d MemUsed:        %8lu kB\n"
73 		       "Node %d Active:         %8lu kB\n"
74 		       "Node %d Inactive:       %8lu kB\n"
75 		       "Node %d Active(anon):   %8lu kB\n"
76 		       "Node %d Inactive(anon): %8lu kB\n"
77 		       "Node %d Active(file):   %8lu kB\n"
78 		       "Node %d Inactive(file): %8lu kB\n"
79 		       "Node %d Unevictable:    %8lu kB\n"
80 		       "Node %d Mlocked:        %8lu kB\n",
81 		       nid, K(i.totalram),
82 		       nid, K(i.freeram),
83 		       nid, K(i.totalram - i.freeram),
84 		       nid, K(node_page_state(nid, NR_ACTIVE_ANON) +
85 				node_page_state(nid, NR_ACTIVE_FILE)),
86 		       nid, K(node_page_state(nid, NR_INACTIVE_ANON) +
87 				node_page_state(nid, NR_INACTIVE_FILE)),
88 		       nid, K(node_page_state(nid, NR_ACTIVE_ANON)),
89 		       nid, K(node_page_state(nid, NR_INACTIVE_ANON)),
90 		       nid, K(node_page_state(nid, NR_ACTIVE_FILE)),
91 		       nid, K(node_page_state(nid, NR_INACTIVE_FILE)),
92 		       nid, K(node_page_state(nid, NR_UNEVICTABLE)),
93 		       nid, K(node_page_state(nid, NR_MLOCK)));
94 
95 #ifdef CONFIG_HIGHMEM
96 	n += sprintf(buf + n,
97 		       "Node %d HighTotal:      %8lu kB\n"
98 		       "Node %d HighFree:       %8lu kB\n"
99 		       "Node %d LowTotal:       %8lu kB\n"
100 		       "Node %d LowFree:        %8lu kB\n",
101 		       nid, K(i.totalhigh),
102 		       nid, K(i.freehigh),
103 		       nid, K(i.totalram - i.totalhigh),
104 		       nid, K(i.freeram - i.freehigh));
105 #endif
106 	n += sprintf(buf + n,
107 		       "Node %d Dirty:          %8lu kB\n"
108 		       "Node %d Writeback:      %8lu kB\n"
109 		       "Node %d FilePages:      %8lu kB\n"
110 		       "Node %d Mapped:         %8lu kB\n"
111 		       "Node %d AnonPages:      %8lu kB\n"
112 		       "Node %d Shmem:          %8lu kB\n"
113 		       "Node %d KernelStack:    %8lu kB\n"
114 		       "Node %d PageTables:     %8lu kB\n"
115 		       "Node %d NFS_Unstable:   %8lu kB\n"
116 		       "Node %d Bounce:         %8lu kB\n"
117 		       "Node %d WritebackTmp:   %8lu kB\n"
118 		       "Node %d Slab:           %8lu kB\n"
119 		       "Node %d SReclaimable:   %8lu kB\n"
120 		       "Node %d SUnreclaim:     %8lu kB\n"
121 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
122 		       "Node %d AnonHugePages:  %8lu kB\n"
123 #endif
124 			,
125 		       nid, K(node_page_state(nid, NR_FILE_DIRTY)),
126 		       nid, K(node_page_state(nid, NR_WRITEBACK)),
127 		       nid, K(node_page_state(nid, NR_FILE_PAGES)),
128 		       nid, K(node_page_state(nid, NR_FILE_MAPPED)),
129 		       nid, K(node_page_state(nid, NR_ANON_PAGES)
130 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
131 			+ node_page_state(nid, NR_ANON_TRANSPARENT_HUGEPAGES) *
132 			HPAGE_PMD_NR
133 #endif
134 		       ),
135 		       nid, K(node_page_state(nid, NR_SHMEM)),
136 		       nid, node_page_state(nid, NR_KERNEL_STACK) *
137 				THREAD_SIZE / 1024,
138 		       nid, K(node_page_state(nid, NR_PAGETABLE)),
139 		       nid, K(node_page_state(nid, NR_UNSTABLE_NFS)),
140 		       nid, K(node_page_state(nid, NR_BOUNCE)),
141 		       nid, K(node_page_state(nid, NR_WRITEBACK_TEMP)),
142 		       nid, K(node_page_state(nid, NR_SLAB_RECLAIMABLE) +
143 				node_page_state(nid, NR_SLAB_UNRECLAIMABLE)),
144 		       nid, K(node_page_state(nid, NR_SLAB_RECLAIMABLE)),
145 		       nid, K(node_page_state(nid, NR_SLAB_UNRECLAIMABLE))
146 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
147 			, nid,
148 			K(node_page_state(nid, NR_ANON_TRANSPARENT_HUGEPAGES) *
149 			HPAGE_PMD_NR)
150 #endif
151 		       );
152 	n += hugetlb_report_node_meminfo(nid, buf + n);
153 	return n;
154 }
155 
156 #undef K
157 static SYSDEV_ATTR(meminfo, S_IRUGO, node_read_meminfo, NULL);
158 
159 static ssize_t node_read_numastat(struct sys_device * dev,
160 				struct sysdev_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 SYSDEV_ATTR(numastat, S_IRUGO, node_read_numastat, NULL);
177 
178 static ssize_t node_read_vmstat(struct sys_device *dev,
179 				struct sysdev_attribute *attr, char *buf)
180 {
181 	int nid = dev->id;
182 	return sprintf(buf,
183 		"nr_written %lu\n"
184 		"nr_dirtied %lu\n",
185 		node_page_state(nid, NR_WRITTEN),
186 		node_page_state(nid, NR_DIRTIED));
187 }
188 static SYSDEV_ATTR(vmstat, S_IRUGO, node_read_vmstat, NULL);
189 
190 static ssize_t node_read_distance(struct sys_device * dev,
191 			struct sysdev_attribute *attr, char * buf)
192 {
193 	int nid = dev->id;
194 	int len = 0;
195 	int i;
196 
197 	/*
198 	 * buf is currently PAGE_SIZE in length and each node needs 4 chars
199 	 * at the most (distance + space or newline).
200 	 */
201 	BUILD_BUG_ON(MAX_NUMNODES * 4 > PAGE_SIZE);
202 
203 	for_each_online_node(i)
204 		len += sprintf(buf + len, "%s%d", i ? " " : "", node_distance(nid, i));
205 
206 	len += sprintf(buf + len, "\n");
207 	return len;
208 }
209 static SYSDEV_ATTR(distance, S_IRUGO, node_read_distance, NULL);
210 
211 #ifdef CONFIG_HUGETLBFS
212 /*
213  * hugetlbfs per node attributes registration interface:
214  * When/if hugetlb[fs] subsystem initializes [sometime after this module],
215  * it will register its per node attributes for all online nodes with
216  * memory.  It will also call register_hugetlbfs_with_node(), below, to
217  * register its attribute registration functions with this node driver.
218  * Once these hooks have been initialized, the node driver will call into
219  * the hugetlb module to [un]register attributes for hot-plugged nodes.
220  */
221 static node_registration_func_t __hugetlb_register_node;
222 static node_registration_func_t __hugetlb_unregister_node;
223 
224 static inline bool hugetlb_register_node(struct node *node)
225 {
226 	if (__hugetlb_register_node &&
227 			node_state(node->sysdev.id, N_HIGH_MEMORY)) {
228 		__hugetlb_register_node(node);
229 		return true;
230 	}
231 	return false;
232 }
233 
234 static inline void hugetlb_unregister_node(struct node *node)
235 {
236 	if (__hugetlb_unregister_node)
237 		__hugetlb_unregister_node(node);
238 }
239 
240 void register_hugetlbfs_with_node(node_registration_func_t doregister,
241 				  node_registration_func_t unregister)
242 {
243 	__hugetlb_register_node   = doregister;
244 	__hugetlb_unregister_node = unregister;
245 }
246 #else
247 static inline void hugetlb_register_node(struct node *node) {}
248 
249 static inline void hugetlb_unregister_node(struct node *node) {}
250 #endif
251 
252 
253 /*
254  * register_node - Setup a sysfs device for a node.
255  * @num - Node number to use when creating the device.
256  *
257  * Initialize and register the node device.
258  */
259 int register_node(struct node *node, int num, struct node *parent)
260 {
261 	int error;
262 
263 	node->sysdev.id = num;
264 	node->sysdev.cls = &node_class;
265 	error = sysdev_register(&node->sysdev);
266 
267 	if (!error){
268 		sysdev_create_file(&node->sysdev, &attr_cpumap);
269 		sysdev_create_file(&node->sysdev, &attr_cpulist);
270 		sysdev_create_file(&node->sysdev, &attr_meminfo);
271 		sysdev_create_file(&node->sysdev, &attr_numastat);
272 		sysdev_create_file(&node->sysdev, &attr_distance);
273 		sysdev_create_file(&node->sysdev, &attr_vmstat);
274 
275 		scan_unevictable_register_node(node);
276 
277 		hugetlb_register_node(node);
278 
279 		compaction_register_node(node);
280 	}
281 	return error;
282 }
283 
284 /**
285  * unregister_node - unregister a node device
286  * @node: node going away
287  *
288  * Unregisters a node device @node.  All the devices on the node must be
289  * unregistered before calling this function.
290  */
291 void unregister_node(struct node *node)
292 {
293 	sysdev_remove_file(&node->sysdev, &attr_cpumap);
294 	sysdev_remove_file(&node->sysdev, &attr_cpulist);
295 	sysdev_remove_file(&node->sysdev, &attr_meminfo);
296 	sysdev_remove_file(&node->sysdev, &attr_numastat);
297 	sysdev_remove_file(&node->sysdev, &attr_distance);
298 	sysdev_remove_file(&node->sysdev, &attr_vmstat);
299 
300 	scan_unevictable_unregister_node(node);
301 	hugetlb_unregister_node(node);		/* no-op, if memoryless node */
302 
303 	sysdev_unregister(&node->sysdev);
304 }
305 
306 struct node node_devices[MAX_NUMNODES];
307 
308 /*
309  * register cpu under node
310  */
311 int register_cpu_under_node(unsigned int cpu, unsigned int nid)
312 {
313 	int ret;
314 	struct sys_device *obj;
315 
316 	if (!node_online(nid))
317 		return 0;
318 
319 	obj = get_cpu_sysdev(cpu);
320 	if (!obj)
321 		return 0;
322 
323 	ret = sysfs_create_link(&node_devices[nid].sysdev.kobj,
324 				&obj->kobj,
325 				kobject_name(&obj->kobj));
326 	if (ret)
327 		return ret;
328 
329 	return sysfs_create_link(&obj->kobj,
330 				 &node_devices[nid].sysdev.kobj,
331 				 kobject_name(&node_devices[nid].sysdev.kobj));
332 }
333 
334 int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
335 {
336 	struct sys_device *obj;
337 
338 	if (!node_online(nid))
339 		return 0;
340 
341 	obj = get_cpu_sysdev(cpu);
342 	if (!obj)
343 		return 0;
344 
345 	sysfs_remove_link(&node_devices[nid].sysdev.kobj,
346 			  kobject_name(&obj->kobj));
347 	sysfs_remove_link(&obj->kobj,
348 			  kobject_name(&node_devices[nid].sysdev.kobj));
349 
350 	return 0;
351 }
352 
353 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
354 #define page_initialized(page)  (page->lru.next)
355 
356 static int get_nid_for_pfn(unsigned long pfn)
357 {
358 	struct page *page;
359 
360 	if (!pfn_valid_within(pfn))
361 		return -1;
362 	page = pfn_to_page(pfn);
363 	if (!page_initialized(page))
364 		return -1;
365 	return pfn_to_nid(pfn);
366 }
367 
368 /* register memory section under specified node if it spans that node */
369 int register_mem_sect_under_node(struct memory_block *mem_blk, int nid)
370 {
371 	int ret;
372 	unsigned long pfn, sect_start_pfn, sect_end_pfn;
373 
374 	if (!mem_blk)
375 		return -EFAULT;
376 	if (!node_online(nid))
377 		return 0;
378 	sect_start_pfn = section_nr_to_pfn(mem_blk->phys_index);
379 	sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
380 	for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
381 		int page_nid;
382 
383 		page_nid = get_nid_for_pfn(pfn);
384 		if (page_nid < 0)
385 			continue;
386 		if (page_nid != nid)
387 			continue;
388 		ret = sysfs_create_link_nowarn(&node_devices[nid].sysdev.kobj,
389 					&mem_blk->sysdev.kobj,
390 					kobject_name(&mem_blk->sysdev.kobj));
391 		if (ret)
392 			return ret;
393 
394 		return sysfs_create_link_nowarn(&mem_blk->sysdev.kobj,
395 				&node_devices[nid].sysdev.kobj,
396 				kobject_name(&node_devices[nid].sysdev.kobj));
397 	}
398 	/* mem section does not span the specified node */
399 	return 0;
400 }
401 
402 /* unregister memory section under all nodes that it spans */
403 int unregister_mem_sect_under_nodes(struct memory_block *mem_blk)
404 {
405 	NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
406 	unsigned long pfn, sect_start_pfn, sect_end_pfn;
407 
408 	if (!mem_blk) {
409 		NODEMASK_FREE(unlinked_nodes);
410 		return -EFAULT;
411 	}
412 	if (!unlinked_nodes)
413 		return -ENOMEM;
414 	nodes_clear(*unlinked_nodes);
415 	sect_start_pfn = section_nr_to_pfn(mem_blk->phys_index);
416 	sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
417 	for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
418 		int nid;
419 
420 		nid = get_nid_for_pfn(pfn);
421 		if (nid < 0)
422 			continue;
423 		if (!node_online(nid))
424 			continue;
425 		if (node_test_and_set(nid, *unlinked_nodes))
426 			continue;
427 		sysfs_remove_link(&node_devices[nid].sysdev.kobj,
428 			 kobject_name(&mem_blk->sysdev.kobj));
429 		sysfs_remove_link(&mem_blk->sysdev.kobj,
430 			 kobject_name(&node_devices[nid].sysdev.kobj));
431 	}
432 	NODEMASK_FREE(unlinked_nodes);
433 	return 0;
434 }
435 
436 static int link_mem_sections(int nid)
437 {
438 	unsigned long start_pfn = NODE_DATA(nid)->node_start_pfn;
439 	unsigned long end_pfn = start_pfn + NODE_DATA(nid)->node_spanned_pages;
440 	unsigned long pfn;
441 	struct memory_block *mem_blk = NULL;
442 	int err = 0;
443 
444 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
445 		unsigned long section_nr = pfn_to_section_nr(pfn);
446 		struct mem_section *mem_sect;
447 		int ret;
448 
449 		if (!present_section_nr(section_nr))
450 			continue;
451 		mem_sect = __nr_to_section(section_nr);
452 		mem_blk = find_memory_block_hinted(mem_sect, mem_blk);
453 		ret = register_mem_sect_under_node(mem_blk, nid);
454 		if (!err)
455 			err = ret;
456 
457 		/* discard ref obtained in find_memory_block() */
458 	}
459 
460 	if (mem_blk)
461 		kobject_put(&mem_blk->sysdev.kobj);
462 	return err;
463 }
464 
465 #ifdef CONFIG_HUGETLBFS
466 /*
467  * Handle per node hstate attribute [un]registration on transistions
468  * to/from memoryless state.
469  */
470 static void node_hugetlb_work(struct work_struct *work)
471 {
472 	struct node *node = container_of(work, struct node, node_work);
473 
474 	/*
475 	 * We only get here when a node transitions to/from memoryless state.
476 	 * We can detect which transition occurred by examining whether the
477 	 * node has memory now.  hugetlb_register_node() already check this
478 	 * so we try to register the attributes.  If that fails, then the
479 	 * node has transitioned to memoryless, try to unregister the
480 	 * attributes.
481 	 */
482 	if (!hugetlb_register_node(node))
483 		hugetlb_unregister_node(node);
484 }
485 
486 static void init_node_hugetlb_work(int nid)
487 {
488 	INIT_WORK(&node_devices[nid].node_work, node_hugetlb_work);
489 }
490 
491 static int node_memory_callback(struct notifier_block *self,
492 				unsigned long action, void *arg)
493 {
494 	struct memory_notify *mnb = arg;
495 	int nid = mnb->status_change_nid;
496 
497 	switch (action) {
498 	case MEM_ONLINE:
499 	case MEM_OFFLINE:
500 		/*
501 		 * offload per node hstate [un]registration to a work thread
502 		 * when transitioning to/from memoryless state.
503 		 */
504 		if (nid != NUMA_NO_NODE)
505 			schedule_work(&node_devices[nid].node_work);
506 		break;
507 
508 	case MEM_GOING_ONLINE:
509 	case MEM_GOING_OFFLINE:
510 	case MEM_CANCEL_ONLINE:
511 	case MEM_CANCEL_OFFLINE:
512 	default:
513 		break;
514 	}
515 
516 	return NOTIFY_OK;
517 }
518 #endif	/* CONFIG_HUGETLBFS */
519 #else	/* !CONFIG_MEMORY_HOTPLUG_SPARSE */
520 
521 static int link_mem_sections(int nid) { return 0; }
522 #endif	/* CONFIG_MEMORY_HOTPLUG_SPARSE */
523 
524 #if !defined(CONFIG_MEMORY_HOTPLUG_SPARSE) || \
525     !defined(CONFIG_HUGETLBFS)
526 static inline int node_memory_callback(struct notifier_block *self,
527 				unsigned long action, void *arg)
528 {
529 	return NOTIFY_OK;
530 }
531 
532 static void init_node_hugetlb_work(int nid) { }
533 
534 #endif
535 
536 int register_one_node(int nid)
537 {
538 	int error = 0;
539 	int cpu;
540 
541 	if (node_online(nid)) {
542 		int p_node = parent_node(nid);
543 		struct node *parent = NULL;
544 
545 		if (p_node != nid)
546 			parent = &node_devices[p_node];
547 
548 		error = register_node(&node_devices[nid], nid, parent);
549 
550 		/* link cpu under this node */
551 		for_each_present_cpu(cpu) {
552 			if (cpu_to_node(cpu) == nid)
553 				register_cpu_under_node(cpu, nid);
554 		}
555 
556 		/* link memory sections under this node */
557 		error = link_mem_sections(nid);
558 
559 		/* initialize work queue for memory hot plug */
560 		init_node_hugetlb_work(nid);
561 	}
562 
563 	return error;
564 
565 }
566 
567 void unregister_one_node(int nid)
568 {
569 	unregister_node(&node_devices[nid]);
570 }
571 
572 /*
573  * node states attributes
574  */
575 
576 static ssize_t print_nodes_state(enum node_states state, char *buf)
577 {
578 	int n;
579 
580 	n = nodelist_scnprintf(buf, PAGE_SIZE, node_states[state]);
581 	if (n > 0 && PAGE_SIZE > n + 1) {
582 		*(buf + n++) = '\n';
583 		*(buf + n++) = '\0';
584 	}
585 	return n;
586 }
587 
588 struct node_attr {
589 	struct sysdev_class_attribute attr;
590 	enum node_states state;
591 };
592 
593 static ssize_t show_node_state(struct sysdev_class *class,
594 			       struct sysdev_class_attribute *attr, char *buf)
595 {
596 	struct node_attr *na = container_of(attr, struct node_attr, attr);
597 	return print_nodes_state(na->state, buf);
598 }
599 
600 #define _NODE_ATTR(name, state) \
601 	{ _SYSDEV_CLASS_ATTR(name, 0444, show_node_state, NULL), state }
602 
603 static struct node_attr node_state_attr[] = {
604 	_NODE_ATTR(possible, N_POSSIBLE),
605 	_NODE_ATTR(online, N_ONLINE),
606 	_NODE_ATTR(has_normal_memory, N_NORMAL_MEMORY),
607 	_NODE_ATTR(has_cpu, N_CPU),
608 #ifdef CONFIG_HIGHMEM
609 	_NODE_ATTR(has_high_memory, N_HIGH_MEMORY),
610 #endif
611 };
612 
613 static struct sysdev_class_attribute *node_state_attrs[] = {
614 	&node_state_attr[0].attr,
615 	&node_state_attr[1].attr,
616 	&node_state_attr[2].attr,
617 	&node_state_attr[3].attr,
618 #ifdef CONFIG_HIGHMEM
619 	&node_state_attr[4].attr,
620 #endif
621 	NULL
622 };
623 
624 #define NODE_CALLBACK_PRI	2	/* lower than SLAB */
625 static int __init register_node_type(void)
626 {
627 	int ret;
628 
629  	BUILD_BUG_ON(ARRAY_SIZE(node_state_attr) != NR_NODE_STATES);
630  	BUILD_BUG_ON(ARRAY_SIZE(node_state_attrs)-1 != NR_NODE_STATES);
631 
632 	ret = sysdev_class_register(&node_class);
633 	if (!ret) {
634 		hotplug_memory_notifier(node_memory_callback,
635 					NODE_CALLBACK_PRI);
636 	}
637 
638 	/*
639 	 * Note:  we're not going to unregister the node class if we fail
640 	 * to register the node state class attribute files.
641 	 */
642 	return ret;
643 }
644 postcore_initcall(register_node_type);
645