xref: /linux/drivers/base/node.c (revision 80d443e8876602be2c130f79c4de81e12e2a700d)
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 pglist_data *pgdat = NODE_DATA(nid);
60 	struct sysinfo i;
61 
62 	si_meminfo_node(&i, nid);
63 	n = sprintf(buf,
64 		       "Node %d MemTotal:       %8lu kB\n"
65 		       "Node %d MemFree:        %8lu kB\n"
66 		       "Node %d MemUsed:        %8lu kB\n"
67 		       "Node %d Active:         %8lu kB\n"
68 		       "Node %d Inactive:       %8lu kB\n"
69 		       "Node %d Active(anon):   %8lu kB\n"
70 		       "Node %d Inactive(anon): %8lu kB\n"
71 		       "Node %d Active(file):   %8lu kB\n"
72 		       "Node %d Inactive(file): %8lu kB\n"
73 		       "Node %d Unevictable:    %8lu kB\n"
74 		       "Node %d Mlocked:        %8lu kB\n",
75 		       nid, K(i.totalram),
76 		       nid, K(i.freeram),
77 		       nid, K(i.totalram - i.freeram),
78 		       nid, K(node_page_state(pgdat, NR_ACTIVE_ANON) +
79 				node_page_state(pgdat, NR_ACTIVE_FILE)),
80 		       nid, K(node_page_state(pgdat, NR_INACTIVE_ANON) +
81 				node_page_state(pgdat, NR_INACTIVE_FILE)),
82 		       nid, K(node_page_state(pgdat, NR_ACTIVE_ANON)),
83 		       nid, K(node_page_state(pgdat, NR_INACTIVE_ANON)),
84 		       nid, K(node_page_state(pgdat, NR_ACTIVE_FILE)),
85 		       nid, K(node_page_state(pgdat, NR_INACTIVE_FILE)),
86 		       nid, K(node_page_state(pgdat, NR_UNEVICTABLE)),
87 		       nid, K(sum_zone_node_page_state(nid, NR_MLOCK)));
88 
89 #ifdef CONFIG_HIGHMEM
90 	n += sprintf(buf + n,
91 		       "Node %d HighTotal:      %8lu kB\n"
92 		       "Node %d HighFree:       %8lu kB\n"
93 		       "Node %d LowTotal:       %8lu kB\n"
94 		       "Node %d LowFree:        %8lu kB\n",
95 		       nid, K(i.totalhigh),
96 		       nid, K(i.freehigh),
97 		       nid, K(i.totalram - i.totalhigh),
98 		       nid, K(i.freeram - i.freehigh));
99 #endif
100 	n += sprintf(buf + n,
101 		       "Node %d Dirty:          %8lu kB\n"
102 		       "Node %d Writeback:      %8lu kB\n"
103 		       "Node %d FilePages:      %8lu kB\n"
104 		       "Node %d Mapped:         %8lu kB\n"
105 		       "Node %d AnonPages:      %8lu kB\n"
106 		       "Node %d Shmem:          %8lu kB\n"
107 		       "Node %d KernelStack:    %8lu kB\n"
108 		       "Node %d PageTables:     %8lu kB\n"
109 		       "Node %d NFS_Unstable:   %8lu kB\n"
110 		       "Node %d Bounce:         %8lu kB\n"
111 		       "Node %d WritebackTmp:   %8lu kB\n"
112 		       "Node %d Slab:           %8lu kB\n"
113 		       "Node %d SReclaimable:   %8lu kB\n"
114 		       "Node %d SUnreclaim:     %8lu kB\n"
115 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
116 		       "Node %d AnonHugePages:  %8lu kB\n"
117 		       "Node %d ShmemHugePages: %8lu kB\n"
118 		       "Node %d ShmemPmdMapped: %8lu kB\n"
119 #endif
120 			,
121 		       nid, K(node_page_state(pgdat, NR_FILE_DIRTY)),
122 		       nid, K(node_page_state(pgdat, NR_WRITEBACK)),
123 		       nid, K(node_page_state(pgdat, NR_FILE_PAGES)),
124 		       nid, K(node_page_state(pgdat, NR_FILE_MAPPED)),
125 		       nid, K(node_page_state(pgdat, NR_ANON_MAPPED)),
126 		       nid, K(i.sharedram),
127 		       nid, sum_zone_node_page_state(nid, NR_KERNEL_STACK_KB),
128 		       nid, K(sum_zone_node_page_state(nid, NR_PAGETABLE)),
129 		       nid, K(node_page_state(pgdat, NR_UNSTABLE_NFS)),
130 		       nid, K(sum_zone_node_page_state(nid, NR_BOUNCE)),
131 		       nid, K(node_page_state(pgdat, NR_WRITEBACK_TEMP)),
132 		       nid, K(sum_zone_node_page_state(nid, NR_SLAB_RECLAIMABLE) +
133 				sum_zone_node_page_state(nid, NR_SLAB_UNRECLAIMABLE)),
134 		       nid, K(sum_zone_node_page_state(nid, NR_SLAB_RECLAIMABLE)),
135 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
136 		       nid, K(sum_zone_node_page_state(nid, NR_SLAB_UNRECLAIMABLE)),
137 		       nid, K(node_page_state(pgdat, NR_ANON_THPS) *
138 				       HPAGE_PMD_NR),
139 		       nid, K(node_page_state(pgdat, NR_SHMEM_THPS) *
140 				       HPAGE_PMD_NR),
141 		       nid, K(node_page_state(pgdat, NR_SHMEM_PMDMAPPED) *
142 				       HPAGE_PMD_NR));
143 #else
144 		       nid, K(sum_zone_node_page_state(nid, NR_SLAB_UNRECLAIMABLE)));
145 #endif
146 	n += hugetlb_report_node_meminfo(nid, buf + n);
147 	return n;
148 }
149 
150 #undef K
151 static DEVICE_ATTR(meminfo, S_IRUGO, node_read_meminfo, NULL);
152 
153 static ssize_t node_read_numastat(struct device *dev,
154 				struct device_attribute *attr, char *buf)
155 {
156 	return sprintf(buf,
157 		       "numa_hit %lu\n"
158 		       "numa_miss %lu\n"
159 		       "numa_foreign %lu\n"
160 		       "interleave_hit %lu\n"
161 		       "local_node %lu\n"
162 		       "other_node %lu\n",
163 		       sum_zone_node_page_state(dev->id, NUMA_HIT),
164 		       sum_zone_node_page_state(dev->id, NUMA_MISS),
165 		       sum_zone_node_page_state(dev->id, NUMA_FOREIGN),
166 		       sum_zone_node_page_state(dev->id, NUMA_INTERLEAVE_HIT),
167 		       sum_zone_node_page_state(dev->id, NUMA_LOCAL),
168 		       sum_zone_node_page_state(dev->id, NUMA_OTHER));
169 }
170 static DEVICE_ATTR(numastat, S_IRUGO, node_read_numastat, NULL);
171 
172 static ssize_t node_read_vmstat(struct device *dev,
173 				struct device_attribute *attr, char *buf)
174 {
175 	int nid = dev->id;
176 	struct pglist_data *pgdat = NODE_DATA(nid);
177 	int i;
178 	int n = 0;
179 
180 	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
181 		n += sprintf(buf+n, "%s %lu\n", vmstat_text[i],
182 			     sum_zone_node_page_state(nid, i));
183 
184 	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
185 		n += sprintf(buf+n, "%s %lu\n",
186 			     vmstat_text[i + NR_VM_ZONE_STAT_ITEMS],
187 			     node_page_state(pgdat, 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 static struct attribute *node_dev_attrs[] = {
215 	&dev_attr_cpumap.attr,
216 	&dev_attr_cpulist.attr,
217 	&dev_attr_meminfo.attr,
218 	&dev_attr_numastat.attr,
219 	&dev_attr_distance.attr,
220 	&dev_attr_vmstat.attr,
221 	NULL
222 };
223 ATTRIBUTE_GROUPS(node_dev);
224 
225 #ifdef CONFIG_HUGETLBFS
226 /*
227  * hugetlbfs per node attributes registration interface:
228  * When/if hugetlb[fs] subsystem initializes [sometime after this module],
229  * it will register its per node attributes for all online nodes with
230  * memory.  It will also call register_hugetlbfs_with_node(), below, to
231  * register its attribute registration functions with this node driver.
232  * Once these hooks have been initialized, the node driver will call into
233  * the hugetlb module to [un]register attributes for hot-plugged nodes.
234  */
235 static node_registration_func_t __hugetlb_register_node;
236 static node_registration_func_t __hugetlb_unregister_node;
237 
238 static inline bool hugetlb_register_node(struct node *node)
239 {
240 	if (__hugetlb_register_node &&
241 			node_state(node->dev.id, N_MEMORY)) {
242 		__hugetlb_register_node(node);
243 		return true;
244 	}
245 	return false;
246 }
247 
248 static inline void hugetlb_unregister_node(struct node *node)
249 {
250 	if (__hugetlb_unregister_node)
251 		__hugetlb_unregister_node(node);
252 }
253 
254 void register_hugetlbfs_with_node(node_registration_func_t doregister,
255 				  node_registration_func_t unregister)
256 {
257 	__hugetlb_register_node   = doregister;
258 	__hugetlb_unregister_node = unregister;
259 }
260 #else
261 static inline void hugetlb_register_node(struct node *node) {}
262 
263 static inline void hugetlb_unregister_node(struct node *node) {}
264 #endif
265 
266 static void node_device_release(struct device *dev)
267 {
268 	struct node *node = to_node(dev);
269 
270 #if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) && defined(CONFIG_HUGETLBFS)
271 	/*
272 	 * We schedule the work only when a memory section is
273 	 * onlined/offlined on this node. When we come here,
274 	 * all the memory on this node has been offlined,
275 	 * so we won't enqueue new work to this work.
276 	 *
277 	 * The work is using node->node_work, so we should
278 	 * flush work before freeing the memory.
279 	 */
280 	flush_work(&node->node_work);
281 #endif
282 	kfree(node);
283 }
284 
285 /*
286  * register_node - Setup a sysfs device for a node.
287  * @num - Node number to use when creating the device.
288  *
289  * Initialize and register the node device.
290  */
291 static int register_node(struct node *node, int num, struct node *parent)
292 {
293 	int error;
294 
295 	node->dev.id = num;
296 	node->dev.bus = &node_subsys;
297 	node->dev.release = node_device_release;
298 	node->dev.groups = node_dev_groups;
299 	error = device_register(&node->dev);
300 
301 	if (!error){
302 		hugetlb_register_node(node);
303 
304 		compaction_register_node(node);
305 	}
306 	return error;
307 }
308 
309 /**
310  * unregister_node - unregister a node device
311  * @node: node going away
312  *
313  * Unregisters a node device @node.  All the devices on the node must be
314  * unregistered before calling this function.
315  */
316 void unregister_node(struct node *node)
317 {
318 	hugetlb_unregister_node(node);		/* no-op, if memoryless node */
319 
320 	device_unregister(&node->dev);
321 }
322 
323 struct node *node_devices[MAX_NUMNODES];
324 
325 /*
326  * register cpu under node
327  */
328 int register_cpu_under_node(unsigned int cpu, unsigned int nid)
329 {
330 	int ret;
331 	struct device *obj;
332 
333 	if (!node_online(nid))
334 		return 0;
335 
336 	obj = get_cpu_device(cpu);
337 	if (!obj)
338 		return 0;
339 
340 	ret = sysfs_create_link(&node_devices[nid]->dev.kobj,
341 				&obj->kobj,
342 				kobject_name(&obj->kobj));
343 	if (ret)
344 		return ret;
345 
346 	return sysfs_create_link(&obj->kobj,
347 				 &node_devices[nid]->dev.kobj,
348 				 kobject_name(&node_devices[nid]->dev.kobj));
349 }
350 
351 int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
352 {
353 	struct device *obj;
354 
355 	if (!node_online(nid))
356 		return 0;
357 
358 	obj = get_cpu_device(cpu);
359 	if (!obj)
360 		return 0;
361 
362 	sysfs_remove_link(&node_devices[nid]->dev.kobj,
363 			  kobject_name(&obj->kobj));
364 	sysfs_remove_link(&obj->kobj,
365 			  kobject_name(&node_devices[nid]->dev.kobj));
366 
367 	return 0;
368 }
369 
370 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
371 #define page_initialized(page)  (page->lru.next)
372 
373 static int __ref get_nid_for_pfn(unsigned long pfn)
374 {
375 	struct page *page;
376 
377 	if (!pfn_valid_within(pfn))
378 		return -1;
379 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
380 	if (system_state == SYSTEM_BOOTING)
381 		return early_pfn_to_nid(pfn);
382 #endif
383 	page = pfn_to_page(pfn);
384 	if (!page_initialized(page))
385 		return -1;
386 	return pfn_to_nid(pfn);
387 }
388 
389 /* register memory section under specified node if it spans that node */
390 int register_mem_sect_under_node(struct memory_block *mem_blk, int nid)
391 {
392 	int ret;
393 	unsigned long pfn, sect_start_pfn, sect_end_pfn;
394 
395 	if (!mem_blk)
396 		return -EFAULT;
397 	if (!node_online(nid))
398 		return 0;
399 
400 	sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
401 	sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr);
402 	sect_end_pfn += PAGES_PER_SECTION - 1;
403 	for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
404 		int page_nid;
405 
406 		/*
407 		 * memory block could have several absent sections from start.
408 		 * skip pfn range from absent section
409 		 */
410 		if (!pfn_present(pfn)) {
411 			pfn = round_down(pfn + PAGES_PER_SECTION,
412 					 PAGES_PER_SECTION) - 1;
413 			continue;
414 		}
415 
416 		page_nid = get_nid_for_pfn(pfn);
417 		if (page_nid < 0)
418 			continue;
419 		if (page_nid != nid)
420 			continue;
421 		ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj,
422 					&mem_blk->dev.kobj,
423 					kobject_name(&mem_blk->dev.kobj));
424 		if (ret)
425 			return ret;
426 
427 		return sysfs_create_link_nowarn(&mem_blk->dev.kobj,
428 				&node_devices[nid]->dev.kobj,
429 				kobject_name(&node_devices[nid]->dev.kobj));
430 	}
431 	/* mem section does not span the specified node */
432 	return 0;
433 }
434 
435 /* unregister memory section under all nodes that it spans */
436 int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
437 				    unsigned long phys_index)
438 {
439 	NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
440 	unsigned long pfn, sect_start_pfn, sect_end_pfn;
441 
442 	if (!mem_blk) {
443 		NODEMASK_FREE(unlinked_nodes);
444 		return -EFAULT;
445 	}
446 	if (!unlinked_nodes)
447 		return -ENOMEM;
448 	nodes_clear(*unlinked_nodes);
449 
450 	sect_start_pfn = section_nr_to_pfn(phys_index);
451 	sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
452 	for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
453 		int nid;
454 
455 		nid = get_nid_for_pfn(pfn);
456 		if (nid < 0)
457 			continue;
458 		if (!node_online(nid))
459 			continue;
460 		if (node_test_and_set(nid, *unlinked_nodes))
461 			continue;
462 		sysfs_remove_link(&node_devices[nid]->dev.kobj,
463 			 kobject_name(&mem_blk->dev.kobj));
464 		sysfs_remove_link(&mem_blk->dev.kobj,
465 			 kobject_name(&node_devices[nid]->dev.kobj));
466 	}
467 	NODEMASK_FREE(unlinked_nodes);
468 	return 0;
469 }
470 
471 static int link_mem_sections(int nid)
472 {
473 	unsigned long start_pfn = NODE_DATA(nid)->node_start_pfn;
474 	unsigned long end_pfn = start_pfn + NODE_DATA(nid)->node_spanned_pages;
475 	unsigned long pfn;
476 	struct memory_block *mem_blk = NULL;
477 	int err = 0;
478 
479 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
480 		unsigned long section_nr = pfn_to_section_nr(pfn);
481 		struct mem_section *mem_sect;
482 		int ret;
483 
484 		if (!present_section_nr(section_nr))
485 			continue;
486 		mem_sect = __nr_to_section(section_nr);
487 
488 		/* same memblock ? */
489 		if (mem_blk)
490 			if ((section_nr >= mem_blk->start_section_nr) &&
491 			    (section_nr <= mem_blk->end_section_nr))
492 				continue;
493 
494 		mem_blk = find_memory_block_hinted(mem_sect, mem_blk);
495 
496 		ret = register_mem_sect_under_node(mem_blk, nid);
497 		if (!err)
498 			err = ret;
499 
500 		/* discard ref obtained in find_memory_block() */
501 	}
502 
503 	if (mem_blk)
504 		kobject_put(&mem_blk->dev.kobj);
505 	return err;
506 }
507 
508 #ifdef CONFIG_HUGETLBFS
509 /*
510  * Handle per node hstate attribute [un]registration on transistions
511  * to/from memoryless state.
512  */
513 static void node_hugetlb_work(struct work_struct *work)
514 {
515 	struct node *node = container_of(work, struct node, node_work);
516 
517 	/*
518 	 * We only get here when a node transitions to/from memoryless state.
519 	 * We can detect which transition occurred by examining whether the
520 	 * node has memory now.  hugetlb_register_node() already check this
521 	 * so we try to register the attributes.  If that fails, then the
522 	 * node has transitioned to memoryless, try to unregister the
523 	 * attributes.
524 	 */
525 	if (!hugetlb_register_node(node))
526 		hugetlb_unregister_node(node);
527 }
528 
529 static void init_node_hugetlb_work(int nid)
530 {
531 	INIT_WORK(&node_devices[nid]->node_work, node_hugetlb_work);
532 }
533 
534 static int node_memory_callback(struct notifier_block *self,
535 				unsigned long action, void *arg)
536 {
537 	struct memory_notify *mnb = arg;
538 	int nid = mnb->status_change_nid;
539 
540 	switch (action) {
541 	case MEM_ONLINE:
542 	case MEM_OFFLINE:
543 		/*
544 		 * offload per node hstate [un]registration to a work thread
545 		 * when transitioning to/from memoryless state.
546 		 */
547 		if (nid != NUMA_NO_NODE)
548 			schedule_work(&node_devices[nid]->node_work);
549 		break;
550 
551 	case MEM_GOING_ONLINE:
552 	case MEM_GOING_OFFLINE:
553 	case MEM_CANCEL_ONLINE:
554 	case MEM_CANCEL_OFFLINE:
555 	default:
556 		break;
557 	}
558 
559 	return NOTIFY_OK;
560 }
561 #endif	/* CONFIG_HUGETLBFS */
562 #else	/* !CONFIG_MEMORY_HOTPLUG_SPARSE */
563 
564 static int link_mem_sections(int nid) { return 0; }
565 #endif	/* CONFIG_MEMORY_HOTPLUG_SPARSE */
566 
567 #if !defined(CONFIG_MEMORY_HOTPLUG_SPARSE) || \
568     !defined(CONFIG_HUGETLBFS)
569 static inline int node_memory_callback(struct notifier_block *self,
570 				unsigned long action, void *arg)
571 {
572 	return NOTIFY_OK;
573 }
574 
575 static void init_node_hugetlb_work(int nid) { }
576 
577 #endif
578 
579 int register_one_node(int nid)
580 {
581 	int error = 0;
582 	int cpu;
583 
584 	if (node_online(nid)) {
585 		int p_node = parent_node(nid);
586 		struct node *parent = NULL;
587 
588 		if (p_node != nid)
589 			parent = node_devices[p_node];
590 
591 		node_devices[nid] = kzalloc(sizeof(struct node), GFP_KERNEL);
592 		if (!node_devices[nid])
593 			return -ENOMEM;
594 
595 		error = register_node(node_devices[nid], nid, parent);
596 
597 		/* link cpu under this node */
598 		for_each_present_cpu(cpu) {
599 			if (cpu_to_node(cpu) == nid)
600 				register_cpu_under_node(cpu, nid);
601 		}
602 
603 		/* link memory sections under this node */
604 		error = link_mem_sections(nid);
605 
606 		/* initialize work queue for memory hot plug */
607 		init_node_hugetlb_work(nid);
608 	}
609 
610 	return error;
611 
612 }
613 
614 void unregister_one_node(int nid)
615 {
616 	if (!node_devices[nid])
617 		return;
618 
619 	unregister_node(node_devices[nid]);
620 	node_devices[nid] = NULL;
621 }
622 
623 /*
624  * node states attributes
625  */
626 
627 static ssize_t print_nodes_state(enum node_states state, char *buf)
628 {
629 	int n;
630 
631 	n = scnprintf(buf, PAGE_SIZE - 1, "%*pbl",
632 		      nodemask_pr_args(&node_states[state]));
633 	buf[n++] = '\n';
634 	buf[n] = '\0';
635 	return n;
636 }
637 
638 struct node_attr {
639 	struct device_attribute attr;
640 	enum node_states state;
641 };
642 
643 static ssize_t show_node_state(struct device *dev,
644 			       struct device_attribute *attr, char *buf)
645 {
646 	struct node_attr *na = container_of(attr, struct node_attr, attr);
647 	return print_nodes_state(na->state, buf);
648 }
649 
650 #define _NODE_ATTR(name, state) \
651 	{ __ATTR(name, 0444, show_node_state, NULL), state }
652 
653 static struct node_attr node_state_attr[] = {
654 	[N_POSSIBLE] = _NODE_ATTR(possible, N_POSSIBLE),
655 	[N_ONLINE] = _NODE_ATTR(online, N_ONLINE),
656 	[N_NORMAL_MEMORY] = _NODE_ATTR(has_normal_memory, N_NORMAL_MEMORY),
657 #ifdef CONFIG_HIGHMEM
658 	[N_HIGH_MEMORY] = _NODE_ATTR(has_high_memory, N_HIGH_MEMORY),
659 #endif
660 #ifdef CONFIG_MOVABLE_NODE
661 	[N_MEMORY] = _NODE_ATTR(has_memory, N_MEMORY),
662 #endif
663 	[N_CPU] = _NODE_ATTR(has_cpu, N_CPU),
664 };
665 
666 static struct attribute *node_state_attrs[] = {
667 	&node_state_attr[N_POSSIBLE].attr.attr,
668 	&node_state_attr[N_ONLINE].attr.attr,
669 	&node_state_attr[N_NORMAL_MEMORY].attr.attr,
670 #ifdef CONFIG_HIGHMEM
671 	&node_state_attr[N_HIGH_MEMORY].attr.attr,
672 #endif
673 #ifdef CONFIG_MOVABLE_NODE
674 	&node_state_attr[N_MEMORY].attr.attr,
675 #endif
676 	&node_state_attr[N_CPU].attr.attr,
677 	NULL
678 };
679 
680 static struct attribute_group memory_root_attr_group = {
681 	.attrs = node_state_attrs,
682 };
683 
684 static const struct attribute_group *cpu_root_attr_groups[] = {
685 	&memory_root_attr_group,
686 	NULL,
687 };
688 
689 #define NODE_CALLBACK_PRI	2	/* lower than SLAB */
690 static int __init register_node_type(void)
691 {
692 	int ret;
693 
694  	BUILD_BUG_ON(ARRAY_SIZE(node_state_attr) != NR_NODE_STATES);
695  	BUILD_BUG_ON(ARRAY_SIZE(node_state_attrs)-1 != NR_NODE_STATES);
696 
697 	ret = subsys_system_register(&node_subsys, cpu_root_attr_groups);
698 	if (!ret) {
699 		static struct notifier_block node_memory_callback_nb = {
700 			.notifier_call = node_memory_callback,
701 			.priority = NODE_CALLBACK_PRI,
702 		};
703 		register_hotmemory_notifier(&node_memory_callback_nb);
704 	}
705 
706 	/*
707 	 * Note:  we're not going to unregister the node class if we fail
708 	 * to register the node state class attribute files.
709 	 */
710 	return ret;
711 }
712 postcore_initcall(register_node_type);
713