xref: /linux/drivers/base/node.c (revision f2ee442115c9b6219083c019939a9cc0c9abb2f8)
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/vmstat.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 sysdev_class_attribute *node_state_attrs[];
23 
24 static struct sysdev_class node_class = {
25 	.name = "node",
26 	.attrs = node_state_attrs,
27 };
28 
29 
30 static ssize_t node_read_cpumap(struct sys_device *dev, int type, char *buf)
31 {
32 	struct node *node_dev = to_node(dev);
33 	const struct cpumask *mask = cpumask_of_node(node_dev->sysdev.id);
34 	int len;
35 
36 	/* 2008/04/07: buf currently PAGE_SIZE, need 9 chars per 32 bits. */
37 	BUILD_BUG_ON((NR_CPUS/32 * 9) > (PAGE_SIZE-1));
38 
39 	len = type?
40 		cpulist_scnprintf(buf, PAGE_SIZE-2, mask) :
41 		cpumask_scnprintf(buf, PAGE_SIZE-2, mask);
42  	buf[len++] = '\n';
43  	buf[len] = '\0';
44 	return len;
45 }
46 
47 static inline ssize_t node_read_cpumask(struct sys_device *dev,
48 				struct sysdev_attribute *attr, char *buf)
49 {
50 	return node_read_cpumap(dev, 0, buf);
51 }
52 static inline ssize_t node_read_cpulist(struct sys_device *dev,
53 				struct sysdev_attribute *attr, char *buf)
54 {
55 	return node_read_cpumap(dev, 1, buf);
56 }
57 
58 static SYSDEV_ATTR(cpumap,  S_IRUGO, node_read_cpumask, NULL);
59 static SYSDEV_ATTR(cpulist, S_IRUGO, node_read_cpulist, NULL);
60 
61 #define K(x) ((x) << (PAGE_SHIFT - 10))
62 static ssize_t node_read_meminfo(struct sys_device * dev,
63 			struct sysdev_attribute *attr, char * buf)
64 {
65 	int n;
66 	int nid = dev->id;
67 	struct sysinfo i;
68 
69 	si_meminfo_node(&i, nid);
70 	n = sprintf(buf,
71 		       "Node %d MemTotal:       %8lu kB\n"
72 		       "Node %d MemFree:        %8lu kB\n"
73 		       "Node %d MemUsed:        %8lu kB\n"
74 		       "Node %d Active:         %8lu kB\n"
75 		       "Node %d Inactive:       %8lu kB\n"
76 		       "Node %d Active(anon):   %8lu kB\n"
77 		       "Node %d Inactive(anon): %8lu kB\n"
78 		       "Node %d Active(file):   %8lu kB\n"
79 		       "Node %d Inactive(file): %8lu kB\n"
80 		       "Node %d Unevictable:    %8lu kB\n"
81 		       "Node %d Mlocked:        %8lu kB\n",
82 		       nid, K(i.totalram),
83 		       nid, K(i.freeram),
84 		       nid, K(i.totalram - i.freeram),
85 		       nid, K(node_page_state(nid, NR_ACTIVE_ANON) +
86 				node_page_state(nid, NR_ACTIVE_FILE)),
87 		       nid, K(node_page_state(nid, NR_INACTIVE_ANON) +
88 				node_page_state(nid, NR_INACTIVE_FILE)),
89 		       nid, K(node_page_state(nid, NR_ACTIVE_ANON)),
90 		       nid, K(node_page_state(nid, NR_INACTIVE_ANON)),
91 		       nid, K(node_page_state(nid, NR_ACTIVE_FILE)),
92 		       nid, K(node_page_state(nid, NR_INACTIVE_FILE)),
93 		       nid, K(node_page_state(nid, NR_UNEVICTABLE)),
94 		       nid, K(node_page_state(nid, NR_MLOCK)));
95 
96 #ifdef CONFIG_HIGHMEM
97 	n += sprintf(buf + n,
98 		       "Node %d HighTotal:      %8lu kB\n"
99 		       "Node %d HighFree:       %8lu kB\n"
100 		       "Node %d LowTotal:       %8lu kB\n"
101 		       "Node %d LowFree:        %8lu kB\n",
102 		       nid, K(i.totalhigh),
103 		       nid, K(i.freehigh),
104 		       nid, K(i.totalram - i.totalhigh),
105 		       nid, K(i.freeram - i.freehigh));
106 #endif
107 	n += sprintf(buf + n,
108 		       "Node %d Dirty:          %8lu kB\n"
109 		       "Node %d Writeback:      %8lu kB\n"
110 		       "Node %d FilePages:      %8lu kB\n"
111 		       "Node %d Mapped:         %8lu kB\n"
112 		       "Node %d AnonPages:      %8lu kB\n"
113 		       "Node %d Shmem:          %8lu kB\n"
114 		       "Node %d KernelStack:    %8lu kB\n"
115 		       "Node %d PageTables:     %8lu kB\n"
116 		       "Node %d NFS_Unstable:   %8lu kB\n"
117 		       "Node %d Bounce:         %8lu kB\n"
118 		       "Node %d WritebackTmp:   %8lu kB\n"
119 		       "Node %d Slab:           %8lu kB\n"
120 		       "Node %d SReclaimable:   %8lu kB\n"
121 		       "Node %d SUnreclaim:     %8lu kB\n"
122 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
123 		       "Node %d AnonHugePages:  %8lu kB\n"
124 #endif
125 			,
126 		       nid, K(node_page_state(nid, NR_FILE_DIRTY)),
127 		       nid, K(node_page_state(nid, NR_WRITEBACK)),
128 		       nid, K(node_page_state(nid, NR_FILE_PAGES)),
129 		       nid, K(node_page_state(nid, NR_FILE_MAPPED)),
130 		       nid, K(node_page_state(nid, NR_ANON_PAGES)
131 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
132 			+ node_page_state(nid, NR_ANON_TRANSPARENT_HUGEPAGES) *
133 			HPAGE_PMD_NR
134 #endif
135 		       ),
136 		       nid, K(node_page_state(nid, NR_SHMEM)),
137 		       nid, node_page_state(nid, NR_KERNEL_STACK) *
138 				THREAD_SIZE / 1024,
139 		       nid, K(node_page_state(nid, NR_PAGETABLE)),
140 		       nid, K(node_page_state(nid, NR_UNSTABLE_NFS)),
141 		       nid, K(node_page_state(nid, NR_BOUNCE)),
142 		       nid, K(node_page_state(nid, NR_WRITEBACK_TEMP)),
143 		       nid, K(node_page_state(nid, NR_SLAB_RECLAIMABLE) +
144 				node_page_state(nid, NR_SLAB_UNRECLAIMABLE)),
145 		       nid, K(node_page_state(nid, NR_SLAB_RECLAIMABLE)),
146 		       nid, K(node_page_state(nid, NR_SLAB_UNRECLAIMABLE))
147 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
148 			, nid,
149 			K(node_page_state(nid, NR_ANON_TRANSPARENT_HUGEPAGES) *
150 			HPAGE_PMD_NR)
151 #endif
152 		       );
153 	n += hugetlb_report_node_meminfo(nid, buf + n);
154 	return n;
155 }
156 
157 #undef K
158 static SYSDEV_ATTR(meminfo, S_IRUGO, node_read_meminfo, NULL);
159 
160 static ssize_t node_read_numastat(struct sys_device * dev,
161 				struct sysdev_attribute *attr, char * buf)
162 {
163 	return sprintf(buf,
164 		       "numa_hit %lu\n"
165 		       "numa_miss %lu\n"
166 		       "numa_foreign %lu\n"
167 		       "interleave_hit %lu\n"
168 		       "local_node %lu\n"
169 		       "other_node %lu\n",
170 		       node_page_state(dev->id, NUMA_HIT),
171 		       node_page_state(dev->id, NUMA_MISS),
172 		       node_page_state(dev->id, NUMA_FOREIGN),
173 		       node_page_state(dev->id, NUMA_INTERLEAVE_HIT),
174 		       node_page_state(dev->id, NUMA_LOCAL),
175 		       node_page_state(dev->id, NUMA_OTHER));
176 }
177 static SYSDEV_ATTR(numastat, S_IRUGO, node_read_numastat, NULL);
178 
179 static ssize_t node_read_vmstat(struct sys_device *dev,
180 				struct sysdev_attribute *attr, char *buf)
181 {
182 	int nid = dev->id;
183 	int i;
184 	int n = 0;
185 
186 	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
187 		n += sprintf(buf+n, "%s %lu\n", vmstat_text[i],
188 			     node_page_state(nid, i));
189 
190 	return n;
191 }
192 static SYSDEV_ATTR(vmstat, S_IRUGO, node_read_vmstat, NULL);
193 
194 static ssize_t node_read_distance(struct sys_device * dev,
195 			struct sysdev_attribute *attr, char * buf)
196 {
197 	int nid = dev->id;
198 	int len = 0;
199 	int i;
200 
201 	/*
202 	 * buf is currently PAGE_SIZE in length and each node needs 4 chars
203 	 * at the most (distance + space or newline).
204 	 */
205 	BUILD_BUG_ON(MAX_NUMNODES * 4 > PAGE_SIZE);
206 
207 	for_each_online_node(i)
208 		len += sprintf(buf + len, "%s%d", i ? " " : "", node_distance(nid, i));
209 
210 	len += sprintf(buf + len, "\n");
211 	return len;
212 }
213 static SYSDEV_ATTR(distance, S_IRUGO, node_read_distance, NULL);
214 
215 #ifdef CONFIG_HUGETLBFS
216 /*
217  * hugetlbfs per node attributes registration interface:
218  * When/if hugetlb[fs] subsystem initializes [sometime after this module],
219  * it will register its per node attributes for all online nodes with
220  * memory.  It will also call register_hugetlbfs_with_node(), below, to
221  * register its attribute registration functions with this node driver.
222  * Once these hooks have been initialized, the node driver will call into
223  * the hugetlb module to [un]register attributes for hot-plugged nodes.
224  */
225 static node_registration_func_t __hugetlb_register_node;
226 static node_registration_func_t __hugetlb_unregister_node;
227 
228 static inline bool hugetlb_register_node(struct node *node)
229 {
230 	if (__hugetlb_register_node &&
231 			node_state(node->sysdev.id, N_HIGH_MEMORY)) {
232 		__hugetlb_register_node(node);
233 		return true;
234 	}
235 	return false;
236 }
237 
238 static inline void hugetlb_unregister_node(struct node *node)
239 {
240 	if (__hugetlb_unregister_node)
241 		__hugetlb_unregister_node(node);
242 }
243 
244 void register_hugetlbfs_with_node(node_registration_func_t doregister,
245 				  node_registration_func_t unregister)
246 {
247 	__hugetlb_register_node   = doregister;
248 	__hugetlb_unregister_node = unregister;
249 }
250 #else
251 static inline void hugetlb_register_node(struct node *node) {}
252 
253 static inline void hugetlb_unregister_node(struct node *node) {}
254 #endif
255 
256 
257 /*
258  * register_node - Setup a sysfs device for a node.
259  * @num - Node number to use when creating the device.
260  *
261  * Initialize and register the node device.
262  */
263 int register_node(struct node *node, int num, struct node *parent)
264 {
265 	int error;
266 
267 	node->sysdev.id = num;
268 	node->sysdev.cls = &node_class;
269 	error = sysdev_register(&node->sysdev);
270 
271 	if (!error){
272 		sysdev_create_file(&node->sysdev, &attr_cpumap);
273 		sysdev_create_file(&node->sysdev, &attr_cpulist);
274 		sysdev_create_file(&node->sysdev, &attr_meminfo);
275 		sysdev_create_file(&node->sysdev, &attr_numastat);
276 		sysdev_create_file(&node->sysdev, &attr_distance);
277 		sysdev_create_file(&node->sysdev, &attr_vmstat);
278 
279 		scan_unevictable_register_node(node);
280 
281 		hugetlb_register_node(node);
282 
283 		compaction_register_node(node);
284 	}
285 	return error;
286 }
287 
288 /**
289  * unregister_node - unregister a node device
290  * @node: node going away
291  *
292  * Unregisters a node device @node.  All the devices on the node must be
293  * unregistered before calling this function.
294  */
295 void unregister_node(struct node *node)
296 {
297 	sysdev_remove_file(&node->sysdev, &attr_cpumap);
298 	sysdev_remove_file(&node->sysdev, &attr_cpulist);
299 	sysdev_remove_file(&node->sysdev, &attr_meminfo);
300 	sysdev_remove_file(&node->sysdev, &attr_numastat);
301 	sysdev_remove_file(&node->sysdev, &attr_distance);
302 	sysdev_remove_file(&node->sysdev, &attr_vmstat);
303 
304 	scan_unevictable_unregister_node(node);
305 	hugetlb_unregister_node(node);		/* no-op, if memoryless node */
306 
307 	sysdev_unregister(&node->sysdev);
308 }
309 
310 struct node node_devices[MAX_NUMNODES];
311 
312 /*
313  * register cpu under node
314  */
315 int register_cpu_under_node(unsigned int cpu, unsigned int nid)
316 {
317 	int ret;
318 	struct sys_device *obj;
319 
320 	if (!node_online(nid))
321 		return 0;
322 
323 	obj = get_cpu_sysdev(cpu);
324 	if (!obj)
325 		return 0;
326 
327 	ret = sysfs_create_link(&node_devices[nid].sysdev.kobj,
328 				&obj->kobj,
329 				kobject_name(&obj->kobj));
330 	if (ret)
331 		return ret;
332 
333 	return sysfs_create_link(&obj->kobj,
334 				 &node_devices[nid].sysdev.kobj,
335 				 kobject_name(&node_devices[nid].sysdev.kobj));
336 }
337 
338 int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
339 {
340 	struct sys_device *obj;
341 
342 	if (!node_online(nid))
343 		return 0;
344 
345 	obj = get_cpu_sysdev(cpu);
346 	if (!obj)
347 		return 0;
348 
349 	sysfs_remove_link(&node_devices[nid].sysdev.kobj,
350 			  kobject_name(&obj->kobj));
351 	sysfs_remove_link(&obj->kobj,
352 			  kobject_name(&node_devices[nid].sysdev.kobj));
353 
354 	return 0;
355 }
356 
357 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
358 #define page_initialized(page)  (page->lru.next)
359 
360 static int get_nid_for_pfn(unsigned long pfn)
361 {
362 	struct page *page;
363 
364 	if (!pfn_valid_within(pfn))
365 		return -1;
366 	page = pfn_to_page(pfn);
367 	if (!page_initialized(page))
368 		return -1;
369 	return pfn_to_nid(pfn);
370 }
371 
372 /* register memory section under specified node if it spans that node */
373 int register_mem_sect_under_node(struct memory_block *mem_blk, int nid)
374 {
375 	int ret;
376 	unsigned long pfn, sect_start_pfn, sect_end_pfn;
377 
378 	if (!mem_blk)
379 		return -EFAULT;
380 	if (!node_online(nid))
381 		return 0;
382 
383 	sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
384 	sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr);
385 	sect_end_pfn += PAGES_PER_SECTION - 1;
386 	for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
387 		int page_nid;
388 
389 		page_nid = get_nid_for_pfn(pfn);
390 		if (page_nid < 0)
391 			continue;
392 		if (page_nid != nid)
393 			continue;
394 		ret = sysfs_create_link_nowarn(&node_devices[nid].sysdev.kobj,
395 					&mem_blk->sysdev.kobj,
396 					kobject_name(&mem_blk->sysdev.kobj));
397 		if (ret)
398 			return ret;
399 
400 		return sysfs_create_link_nowarn(&mem_blk->sysdev.kobj,
401 				&node_devices[nid].sysdev.kobj,
402 				kobject_name(&node_devices[nid].sysdev.kobj));
403 	}
404 	/* mem section does not span the specified node */
405 	return 0;
406 }
407 
408 /* unregister memory section under all nodes that it spans */
409 int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
410 				    unsigned long phys_index)
411 {
412 	NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
413 	unsigned long pfn, sect_start_pfn, sect_end_pfn;
414 
415 	if (!mem_blk) {
416 		NODEMASK_FREE(unlinked_nodes);
417 		return -EFAULT;
418 	}
419 	if (!unlinked_nodes)
420 		return -ENOMEM;
421 	nodes_clear(*unlinked_nodes);
422 
423 	sect_start_pfn = section_nr_to_pfn(phys_index);
424 	sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
425 	for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
426 		int nid;
427 
428 		nid = get_nid_for_pfn(pfn);
429 		if (nid < 0)
430 			continue;
431 		if (!node_online(nid))
432 			continue;
433 		if (node_test_and_set(nid, *unlinked_nodes))
434 			continue;
435 		sysfs_remove_link(&node_devices[nid].sysdev.kobj,
436 			 kobject_name(&mem_blk->sysdev.kobj));
437 		sysfs_remove_link(&mem_blk->sysdev.kobj,
438 			 kobject_name(&node_devices[nid].sysdev.kobj));
439 	}
440 	NODEMASK_FREE(unlinked_nodes);
441 	return 0;
442 }
443 
444 static int link_mem_sections(int nid)
445 {
446 	unsigned long start_pfn = NODE_DATA(nid)->node_start_pfn;
447 	unsigned long end_pfn = start_pfn + NODE_DATA(nid)->node_spanned_pages;
448 	unsigned long pfn;
449 	struct memory_block *mem_blk = NULL;
450 	int err = 0;
451 
452 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
453 		unsigned long section_nr = pfn_to_section_nr(pfn);
454 		struct mem_section *mem_sect;
455 		int ret;
456 
457 		if (!present_section_nr(section_nr))
458 			continue;
459 		mem_sect = __nr_to_section(section_nr);
460 		mem_blk = find_memory_block_hinted(mem_sect, mem_blk);
461 		ret = register_mem_sect_under_node(mem_blk, nid);
462 		if (!err)
463 			err = ret;
464 
465 		/* discard ref obtained in find_memory_block() */
466 	}
467 
468 	if (mem_blk)
469 		kobject_put(&mem_blk->sysdev.kobj);
470 	return err;
471 }
472 
473 #ifdef CONFIG_HUGETLBFS
474 /*
475  * Handle per node hstate attribute [un]registration on transistions
476  * to/from memoryless state.
477  */
478 static void node_hugetlb_work(struct work_struct *work)
479 {
480 	struct node *node = container_of(work, struct node, node_work);
481 
482 	/*
483 	 * We only get here when a node transitions to/from memoryless state.
484 	 * We can detect which transition occurred by examining whether the
485 	 * node has memory now.  hugetlb_register_node() already check this
486 	 * so we try to register the attributes.  If that fails, then the
487 	 * node has transitioned to memoryless, try to unregister the
488 	 * attributes.
489 	 */
490 	if (!hugetlb_register_node(node))
491 		hugetlb_unregister_node(node);
492 }
493 
494 static void init_node_hugetlb_work(int nid)
495 {
496 	INIT_WORK(&node_devices[nid].node_work, node_hugetlb_work);
497 }
498 
499 static int node_memory_callback(struct notifier_block *self,
500 				unsigned long action, void *arg)
501 {
502 	struct memory_notify *mnb = arg;
503 	int nid = mnb->status_change_nid;
504 
505 	switch (action) {
506 	case MEM_ONLINE:
507 	case MEM_OFFLINE:
508 		/*
509 		 * offload per node hstate [un]registration to a work thread
510 		 * when transitioning to/from memoryless state.
511 		 */
512 		if (nid != NUMA_NO_NODE)
513 			schedule_work(&node_devices[nid].node_work);
514 		break;
515 
516 	case MEM_GOING_ONLINE:
517 	case MEM_GOING_OFFLINE:
518 	case MEM_CANCEL_ONLINE:
519 	case MEM_CANCEL_OFFLINE:
520 	default:
521 		break;
522 	}
523 
524 	return NOTIFY_OK;
525 }
526 #endif	/* CONFIG_HUGETLBFS */
527 #else	/* !CONFIG_MEMORY_HOTPLUG_SPARSE */
528 
529 static int link_mem_sections(int nid) { return 0; }
530 #endif	/* CONFIG_MEMORY_HOTPLUG_SPARSE */
531 
532 #if !defined(CONFIG_MEMORY_HOTPLUG_SPARSE) || \
533     !defined(CONFIG_HUGETLBFS)
534 static inline int node_memory_callback(struct notifier_block *self,
535 				unsigned long action, void *arg)
536 {
537 	return NOTIFY_OK;
538 }
539 
540 static void init_node_hugetlb_work(int nid) { }
541 
542 #endif
543 
544 int register_one_node(int nid)
545 {
546 	int error = 0;
547 	int cpu;
548 
549 	if (node_online(nid)) {
550 		int p_node = parent_node(nid);
551 		struct node *parent = NULL;
552 
553 		if (p_node != nid)
554 			parent = &node_devices[p_node];
555 
556 		error = register_node(&node_devices[nid], nid, parent);
557 
558 		/* link cpu under this node */
559 		for_each_present_cpu(cpu) {
560 			if (cpu_to_node(cpu) == nid)
561 				register_cpu_under_node(cpu, nid);
562 		}
563 
564 		/* link memory sections under this node */
565 		error = link_mem_sections(nid);
566 
567 		/* initialize work queue for memory hot plug */
568 		init_node_hugetlb_work(nid);
569 	}
570 
571 	return error;
572 
573 }
574 
575 void unregister_one_node(int nid)
576 {
577 	unregister_node(&node_devices[nid]);
578 }
579 
580 /*
581  * node states attributes
582  */
583 
584 static ssize_t print_nodes_state(enum node_states state, char *buf)
585 {
586 	int n;
587 
588 	n = nodelist_scnprintf(buf, PAGE_SIZE, node_states[state]);
589 	if (n > 0 && PAGE_SIZE > n + 1) {
590 		*(buf + n++) = '\n';
591 		*(buf + n++) = '\0';
592 	}
593 	return n;
594 }
595 
596 struct node_attr {
597 	struct sysdev_class_attribute attr;
598 	enum node_states state;
599 };
600 
601 static ssize_t show_node_state(struct sysdev_class *class,
602 			       struct sysdev_class_attribute *attr, char *buf)
603 {
604 	struct node_attr *na = container_of(attr, struct node_attr, attr);
605 	return print_nodes_state(na->state, buf);
606 }
607 
608 #define _NODE_ATTR(name, state) \
609 	{ _SYSDEV_CLASS_ATTR(name, 0444, show_node_state, NULL), state }
610 
611 static struct node_attr node_state_attr[] = {
612 	_NODE_ATTR(possible, N_POSSIBLE),
613 	_NODE_ATTR(online, N_ONLINE),
614 	_NODE_ATTR(has_normal_memory, N_NORMAL_MEMORY),
615 	_NODE_ATTR(has_cpu, N_CPU),
616 #ifdef CONFIG_HIGHMEM
617 	_NODE_ATTR(has_high_memory, N_HIGH_MEMORY),
618 #endif
619 };
620 
621 static struct sysdev_class_attribute *node_state_attrs[] = {
622 	&node_state_attr[0].attr,
623 	&node_state_attr[1].attr,
624 	&node_state_attr[2].attr,
625 	&node_state_attr[3].attr,
626 #ifdef CONFIG_HIGHMEM
627 	&node_state_attr[4].attr,
628 #endif
629 	NULL
630 };
631 
632 #define NODE_CALLBACK_PRI	2	/* lower than SLAB */
633 static int __init register_node_type(void)
634 {
635 	int ret;
636 
637  	BUILD_BUG_ON(ARRAY_SIZE(node_state_attr) != NR_NODE_STATES);
638  	BUILD_BUG_ON(ARRAY_SIZE(node_state_attrs)-1 != NR_NODE_STATES);
639 
640 	ret = sysdev_class_register(&node_class);
641 	if (!ret) {
642 		hotplug_memory_notifier(node_memory_callback,
643 					NODE_CALLBACK_PRI);
644 	}
645 
646 	/*
647 	 * Note:  we're not going to unregister the node class if we fail
648 	 * to register the node state class attribute files.
649 	 */
650 	return ret;
651 }
652 postcore_initcall(register_node_type);
653