mm/memory_hotplug: fix leftover use of struct page during hotplug
[sfrench/cifs-2.6.git] / 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                 put_device(&node->dev);
320         else {
321                 hugetlb_register_node(node);
322
323                 compaction_register_node(node);
324         }
325         return error;
326 }
327
328 /**
329  * unregister_node - unregister a node device
330  * @node: node going away
331  *
332  * Unregisters a node device @node.  All the devices on the node must be
333  * unregistered before calling this function.
334  */
335 void unregister_node(struct node *node)
336 {
337         hugetlb_unregister_node(node);          /* no-op, if memoryless node */
338
339         device_unregister(&node->dev);
340 }
341
342 struct node *node_devices[MAX_NUMNODES];
343
344 /*
345  * register cpu under node
346  */
347 int register_cpu_under_node(unsigned int cpu, unsigned int nid)
348 {
349         int ret;
350         struct device *obj;
351
352         if (!node_online(nid))
353                 return 0;
354
355         obj = get_cpu_device(cpu);
356         if (!obj)
357                 return 0;
358
359         ret = sysfs_create_link(&node_devices[nid]->dev.kobj,
360                                 &obj->kobj,
361                                 kobject_name(&obj->kobj));
362         if (ret)
363                 return ret;
364
365         return sysfs_create_link(&obj->kobj,
366                                  &node_devices[nid]->dev.kobj,
367                                  kobject_name(&node_devices[nid]->dev.kobj));
368 }
369
370 int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
371 {
372         struct device *obj;
373
374         if (!node_online(nid))
375                 return 0;
376
377         obj = get_cpu_device(cpu);
378         if (!obj)
379                 return 0;
380
381         sysfs_remove_link(&node_devices[nid]->dev.kobj,
382                           kobject_name(&obj->kobj));
383         sysfs_remove_link(&obj->kobj,
384                           kobject_name(&node_devices[nid]->dev.kobj));
385
386         return 0;
387 }
388
389 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
390 static int __ref get_nid_for_pfn(unsigned long pfn)
391 {
392         if (!pfn_valid_within(pfn))
393                 return -1;
394 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
395         if (system_state < SYSTEM_RUNNING)
396                 return early_pfn_to_nid(pfn);
397 #endif
398         return pfn_to_nid(pfn);
399 }
400
401 /* register memory section under specified node if it spans that node */
402 int register_mem_sect_under_node(struct memory_block *mem_blk, int nid,
403                                  bool check_nid)
404 {
405         int ret;
406         unsigned long pfn, sect_start_pfn, sect_end_pfn;
407
408         if (!mem_blk)
409                 return -EFAULT;
410
411         mem_blk->nid = nid;
412         if (!node_online(nid))
413                 return 0;
414
415         sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
416         sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr);
417         sect_end_pfn += PAGES_PER_SECTION - 1;
418         for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
419                 int page_nid;
420
421                 /*
422                  * memory block could have several absent sections from start.
423                  * skip pfn range from absent section
424                  */
425                 if (!pfn_present(pfn)) {
426                         pfn = round_down(pfn + PAGES_PER_SECTION,
427                                          PAGES_PER_SECTION) - 1;
428                         continue;
429                 }
430
431                 /*
432                  * We need to check if page belongs to nid only for the boot
433                  * case, during hotplug we know that all pages in the memory
434                  * block belong to the same node.
435                  */
436                 if (check_nid) {
437                         page_nid = get_nid_for_pfn(pfn);
438                         if (page_nid < 0)
439                                 continue;
440                         if (page_nid != nid)
441                                 continue;
442                 }
443                 ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj,
444                                         &mem_blk->dev.kobj,
445                                         kobject_name(&mem_blk->dev.kobj));
446                 if (ret)
447                         return ret;
448
449                 return sysfs_create_link_nowarn(&mem_blk->dev.kobj,
450                                 &node_devices[nid]->dev.kobj,
451                                 kobject_name(&node_devices[nid]->dev.kobj));
452         }
453         /* mem section does not span the specified node */
454         return 0;
455 }
456
457 /* unregister memory section under all nodes that it spans */
458 int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
459                                     unsigned long phys_index)
460 {
461         NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
462         unsigned long pfn, sect_start_pfn, sect_end_pfn;
463
464         if (!mem_blk) {
465                 NODEMASK_FREE(unlinked_nodes);
466                 return -EFAULT;
467         }
468         if (!unlinked_nodes)
469                 return -ENOMEM;
470         nodes_clear(*unlinked_nodes);
471
472         sect_start_pfn = section_nr_to_pfn(phys_index);
473         sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
474         for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
475                 int nid;
476
477                 nid = get_nid_for_pfn(pfn);
478                 if (nid < 0)
479                         continue;
480                 if (!node_online(nid))
481                         continue;
482                 if (node_test_and_set(nid, *unlinked_nodes))
483                         continue;
484                 sysfs_remove_link(&node_devices[nid]->dev.kobj,
485                          kobject_name(&mem_blk->dev.kobj));
486                 sysfs_remove_link(&mem_blk->dev.kobj,
487                          kobject_name(&node_devices[nid]->dev.kobj));
488         }
489         NODEMASK_FREE(unlinked_nodes);
490         return 0;
491 }
492
493 int link_mem_sections(int nid, unsigned long start_pfn, unsigned long nr_pages,
494                       bool check_nid)
495 {
496         unsigned long end_pfn = start_pfn + nr_pages;
497         unsigned long pfn;
498         struct memory_block *mem_blk = NULL;
499         int err = 0;
500
501         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
502                 unsigned long section_nr = pfn_to_section_nr(pfn);
503                 struct mem_section *mem_sect;
504                 int ret;
505
506                 if (!present_section_nr(section_nr))
507                         continue;
508                 mem_sect = __nr_to_section(section_nr);
509
510                 /* same memblock ? */
511                 if (mem_blk)
512                         if ((section_nr >= mem_blk->start_section_nr) &&
513                             (section_nr <= mem_blk->end_section_nr))
514                                 continue;
515
516                 mem_blk = find_memory_block_hinted(mem_sect, mem_blk);
517
518                 ret = register_mem_sect_under_node(mem_blk, nid, check_nid);
519                 if (!err)
520                         err = ret;
521
522                 /* discard ref obtained in find_memory_block() */
523         }
524
525         if (mem_blk)
526                 kobject_put(&mem_blk->dev.kobj);
527         return err;
528 }
529
530 #ifdef CONFIG_HUGETLBFS
531 /*
532  * Handle per node hstate attribute [un]registration on transistions
533  * to/from memoryless state.
534  */
535 static void node_hugetlb_work(struct work_struct *work)
536 {
537         struct node *node = container_of(work, struct node, node_work);
538
539         /*
540          * We only get here when a node transitions to/from memoryless state.
541          * We can detect which transition occurred by examining whether the
542          * node has memory now.  hugetlb_register_node() already check this
543          * so we try to register the attributes.  If that fails, then the
544          * node has transitioned to memoryless, try to unregister the
545          * attributes.
546          */
547         if (!hugetlb_register_node(node))
548                 hugetlb_unregister_node(node);
549 }
550
551 static void init_node_hugetlb_work(int nid)
552 {
553         INIT_WORK(&node_devices[nid]->node_work, node_hugetlb_work);
554 }
555
556 static int node_memory_callback(struct notifier_block *self,
557                                 unsigned long action, void *arg)
558 {
559         struct memory_notify *mnb = arg;
560         int nid = mnb->status_change_nid;
561
562         switch (action) {
563         case MEM_ONLINE:
564         case MEM_OFFLINE:
565                 /*
566                  * offload per node hstate [un]registration to a work thread
567                  * when transitioning to/from memoryless state.
568                  */
569                 if (nid != NUMA_NO_NODE)
570                         schedule_work(&node_devices[nid]->node_work);
571                 break;
572
573         case MEM_GOING_ONLINE:
574         case MEM_GOING_OFFLINE:
575         case MEM_CANCEL_ONLINE:
576         case MEM_CANCEL_OFFLINE:
577         default:
578                 break;
579         }
580
581         return NOTIFY_OK;
582 }
583 #endif  /* CONFIG_HUGETLBFS */
584 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
585
586 #if !defined(CONFIG_MEMORY_HOTPLUG_SPARSE) || \
587     !defined(CONFIG_HUGETLBFS)
588 static inline int node_memory_callback(struct notifier_block *self,
589                                 unsigned long action, void *arg)
590 {
591         return NOTIFY_OK;
592 }
593
594 static void init_node_hugetlb_work(int nid) { }
595
596 #endif
597
598 int __register_one_node(int nid)
599 {
600         int error;
601         int cpu;
602
603         node_devices[nid] = kzalloc(sizeof(struct node), GFP_KERNEL);
604         if (!node_devices[nid])
605                 return -ENOMEM;
606
607         error = register_node(node_devices[nid], nid);
608
609         /* link cpu under this node */
610         for_each_present_cpu(cpu) {
611                 if (cpu_to_node(cpu) == nid)
612                         register_cpu_under_node(cpu, nid);
613         }
614
615         /* initialize work queue for memory hot plug */
616         init_node_hugetlb_work(nid);
617
618         return error;
619 }
620
621 void unregister_one_node(int nid)
622 {
623         if (!node_devices[nid])
624                 return;
625
626         unregister_node(node_devices[nid]);
627         node_devices[nid] = NULL;
628 }
629
630 /*
631  * node states attributes
632  */
633
634 static ssize_t print_nodes_state(enum node_states state, char *buf)
635 {
636         int n;
637
638         n = scnprintf(buf, PAGE_SIZE - 1, "%*pbl",
639                       nodemask_pr_args(&node_states[state]));
640         buf[n++] = '\n';
641         buf[n] = '\0';
642         return n;
643 }
644
645 struct node_attr {
646         struct device_attribute attr;
647         enum node_states state;
648 };
649
650 static ssize_t show_node_state(struct device *dev,
651                                struct device_attribute *attr, char *buf)
652 {
653         struct node_attr *na = container_of(attr, struct node_attr, attr);
654         return print_nodes_state(na->state, buf);
655 }
656
657 #define _NODE_ATTR(name, state) \
658         { __ATTR(name, 0444, show_node_state, NULL), state }
659
660 static struct node_attr node_state_attr[] = {
661         [N_POSSIBLE] = _NODE_ATTR(possible, N_POSSIBLE),
662         [N_ONLINE] = _NODE_ATTR(online, N_ONLINE),
663         [N_NORMAL_MEMORY] = _NODE_ATTR(has_normal_memory, N_NORMAL_MEMORY),
664 #ifdef CONFIG_HIGHMEM
665         [N_HIGH_MEMORY] = _NODE_ATTR(has_high_memory, N_HIGH_MEMORY),
666 #endif
667         [N_MEMORY] = _NODE_ATTR(has_memory, N_MEMORY),
668         [N_CPU] = _NODE_ATTR(has_cpu, N_CPU),
669 };
670
671 static struct attribute *node_state_attrs[] = {
672         &node_state_attr[N_POSSIBLE].attr.attr,
673         &node_state_attr[N_ONLINE].attr.attr,
674         &node_state_attr[N_NORMAL_MEMORY].attr.attr,
675 #ifdef CONFIG_HIGHMEM
676         &node_state_attr[N_HIGH_MEMORY].attr.attr,
677 #endif
678         &node_state_attr[N_MEMORY].attr.attr,
679         &node_state_attr[N_CPU].attr.attr,
680         NULL
681 };
682
683 static struct attribute_group memory_root_attr_group = {
684         .attrs = node_state_attrs,
685 };
686
687 static const struct attribute_group *cpu_root_attr_groups[] = {
688         &memory_root_attr_group,
689         NULL,
690 };
691
692 #define NODE_CALLBACK_PRI       2       /* lower than SLAB */
693 static int __init register_node_type(void)
694 {
695         int ret;
696
697         BUILD_BUG_ON(ARRAY_SIZE(node_state_attr) != NR_NODE_STATES);
698         BUILD_BUG_ON(ARRAY_SIZE(node_state_attrs)-1 != NR_NODE_STATES);
699
700         ret = subsys_system_register(&node_subsys, cpu_root_attr_groups);
701         if (!ret) {
702                 static struct notifier_block node_memory_callback_nb = {
703                         .notifier_call = node_memory_callback,
704                         .priority = NODE_CALLBACK_PRI,
705                 };
706                 register_hotmemory_notifier(&node_memory_callback_nb);
707         }
708
709         /*
710          * Note:  we're not going to unregister the node class if we fail
711          * to register the node state class attribute files.
712          */
713         return ret;
714 }
715 postcore_initcall(register_node_type);