xref: /openbmc/linux/drivers/base/memory.c (revision ca55b2fe)
1 /*
2  * Memory subsystem support
3  *
4  * Written by Matt Tolentino <matthew.e.tolentino@intel.com>
5  *            Dave Hansen <haveblue@us.ibm.com>
6  *
7  * This file provides the necessary infrastructure to represent
8  * a SPARSEMEM-memory-model system's physical memory in /sysfs.
9  * All arch-independent code that assumes MEMORY_HOTPLUG requires
10  * SPARSEMEM should be contained here, or in mm/memory_hotplug.c.
11  */
12 
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/topology.h>
16 #include <linux/capability.h>
17 #include <linux/device.h>
18 #include <linux/memory.h>
19 #include <linux/memory_hotplug.h>
20 #include <linux/mm.h>
21 #include <linux/mutex.h>
22 #include <linux/stat.h>
23 #include <linux/slab.h>
24 
25 #include <linux/atomic.h>
26 #include <asm/uaccess.h>
27 
28 static DEFINE_MUTEX(mem_sysfs_mutex);
29 
30 #define MEMORY_CLASS_NAME	"memory"
31 
32 #define to_memory_block(dev) container_of(dev, struct memory_block, dev)
33 
34 static int sections_per_block;
35 
36 static inline int base_memory_block_id(int section_nr)
37 {
38 	return section_nr / sections_per_block;
39 }
40 
41 static int memory_subsys_online(struct device *dev);
42 static int memory_subsys_offline(struct device *dev);
43 
44 static struct bus_type memory_subsys = {
45 	.name = MEMORY_CLASS_NAME,
46 	.dev_name = MEMORY_CLASS_NAME,
47 	.online = memory_subsys_online,
48 	.offline = memory_subsys_offline,
49 };
50 
51 static BLOCKING_NOTIFIER_HEAD(memory_chain);
52 
53 int register_memory_notifier(struct notifier_block *nb)
54 {
55 	return blocking_notifier_chain_register(&memory_chain, nb);
56 }
57 EXPORT_SYMBOL(register_memory_notifier);
58 
59 void unregister_memory_notifier(struct notifier_block *nb)
60 {
61 	blocking_notifier_chain_unregister(&memory_chain, nb);
62 }
63 EXPORT_SYMBOL(unregister_memory_notifier);
64 
65 static ATOMIC_NOTIFIER_HEAD(memory_isolate_chain);
66 
67 int register_memory_isolate_notifier(struct notifier_block *nb)
68 {
69 	return atomic_notifier_chain_register(&memory_isolate_chain, nb);
70 }
71 EXPORT_SYMBOL(register_memory_isolate_notifier);
72 
73 void unregister_memory_isolate_notifier(struct notifier_block *nb)
74 {
75 	atomic_notifier_chain_unregister(&memory_isolate_chain, nb);
76 }
77 EXPORT_SYMBOL(unregister_memory_isolate_notifier);
78 
79 static void memory_block_release(struct device *dev)
80 {
81 	struct memory_block *mem = to_memory_block(dev);
82 
83 	kfree(mem);
84 }
85 
86 unsigned long __weak memory_block_size_bytes(void)
87 {
88 	return MIN_MEMORY_BLOCK_SIZE;
89 }
90 
91 static unsigned long get_memory_block_size(void)
92 {
93 	unsigned long block_sz;
94 
95 	block_sz = memory_block_size_bytes();
96 
97 	/* Validate blk_sz is a power of 2 and not less than section size */
98 	if ((block_sz & (block_sz - 1)) || (block_sz < MIN_MEMORY_BLOCK_SIZE)) {
99 		WARN_ON(1);
100 		block_sz = MIN_MEMORY_BLOCK_SIZE;
101 	}
102 
103 	return block_sz;
104 }
105 
106 /*
107  * use this as the physical section index that this memsection
108  * uses.
109  */
110 
111 static ssize_t show_mem_start_phys_index(struct device *dev,
112 			struct device_attribute *attr, char *buf)
113 {
114 	struct memory_block *mem = to_memory_block(dev);
115 	unsigned long phys_index;
116 
117 	phys_index = mem->start_section_nr / sections_per_block;
118 	return sprintf(buf, "%08lx\n", phys_index);
119 }
120 
121 /*
122  * Show whether the section of memory is likely to be hot-removable
123  */
124 static ssize_t show_mem_removable(struct device *dev,
125 			struct device_attribute *attr, char *buf)
126 {
127 	unsigned long i, pfn;
128 	int ret = 1;
129 	struct memory_block *mem = to_memory_block(dev);
130 
131 	for (i = 0; i < sections_per_block; i++) {
132 		if (!present_section_nr(mem->start_section_nr + i))
133 			continue;
134 		pfn = section_nr_to_pfn(mem->start_section_nr + i);
135 		ret &= is_mem_section_removable(pfn, PAGES_PER_SECTION);
136 	}
137 
138 	return sprintf(buf, "%d\n", ret);
139 }
140 
141 /*
142  * online, offline, going offline, etc.
143  */
144 static ssize_t show_mem_state(struct device *dev,
145 			struct device_attribute *attr, char *buf)
146 {
147 	struct memory_block *mem = to_memory_block(dev);
148 	ssize_t len = 0;
149 
150 	/*
151 	 * We can probably put these states in a nice little array
152 	 * so that they're not open-coded
153 	 */
154 	switch (mem->state) {
155 	case MEM_ONLINE:
156 		len = sprintf(buf, "online\n");
157 		break;
158 	case MEM_OFFLINE:
159 		len = sprintf(buf, "offline\n");
160 		break;
161 	case MEM_GOING_OFFLINE:
162 		len = sprintf(buf, "going-offline\n");
163 		break;
164 	default:
165 		len = sprintf(buf, "ERROR-UNKNOWN-%ld\n",
166 				mem->state);
167 		WARN_ON(1);
168 		break;
169 	}
170 
171 	return len;
172 }
173 
174 int memory_notify(unsigned long val, void *v)
175 {
176 	return blocking_notifier_call_chain(&memory_chain, val, v);
177 }
178 
179 int memory_isolate_notify(unsigned long val, void *v)
180 {
181 	return atomic_notifier_call_chain(&memory_isolate_chain, val, v);
182 }
183 
184 /*
185  * The probe routines leave the pages reserved, just as the bootmem code does.
186  * Make sure they're still that way.
187  */
188 static bool pages_correctly_reserved(unsigned long start_pfn)
189 {
190 	int i, j;
191 	struct page *page;
192 	unsigned long pfn = start_pfn;
193 
194 	/*
195 	 * memmap between sections is not contiguous except with
196 	 * SPARSEMEM_VMEMMAP. We lookup the page once per section
197 	 * and assume memmap is contiguous within each section
198 	 */
199 	for (i = 0; i < sections_per_block; i++, pfn += PAGES_PER_SECTION) {
200 		if (WARN_ON_ONCE(!pfn_valid(pfn)))
201 			return false;
202 		page = pfn_to_page(pfn);
203 
204 		for (j = 0; j < PAGES_PER_SECTION; j++) {
205 			if (PageReserved(page + j))
206 				continue;
207 
208 			printk(KERN_WARNING "section number %ld page number %d "
209 				"not reserved, was it already online?\n",
210 				pfn_to_section_nr(pfn), j);
211 
212 			return false;
213 		}
214 	}
215 
216 	return true;
217 }
218 
219 /*
220  * MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
221  * OK to have direct references to sparsemem variables in here.
222  * Must already be protected by mem_hotplug_begin().
223  */
224 static int
225 memory_block_action(unsigned long phys_index, unsigned long action, int online_type)
226 {
227 	unsigned long start_pfn;
228 	unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
229 	struct page *first_page;
230 	int ret;
231 
232 	start_pfn = section_nr_to_pfn(phys_index);
233 	first_page = pfn_to_page(start_pfn);
234 
235 	switch (action) {
236 	case MEM_ONLINE:
237 		if (!pages_correctly_reserved(start_pfn))
238 			return -EBUSY;
239 
240 		ret = online_pages(start_pfn, nr_pages, online_type);
241 		break;
242 	case MEM_OFFLINE:
243 		ret = offline_pages(start_pfn, nr_pages);
244 		break;
245 	default:
246 		WARN(1, KERN_WARNING "%s(%ld, %ld) unknown action: "
247 		     "%ld\n", __func__, phys_index, action, action);
248 		ret = -EINVAL;
249 	}
250 
251 	return ret;
252 }
253 
254 static int memory_block_change_state(struct memory_block *mem,
255 		unsigned long to_state, unsigned long from_state_req)
256 {
257 	int ret = 0;
258 
259 	if (mem->state != from_state_req)
260 		return -EINVAL;
261 
262 	if (to_state == MEM_OFFLINE)
263 		mem->state = MEM_GOING_OFFLINE;
264 
265 	ret = memory_block_action(mem->start_section_nr, to_state,
266 				mem->online_type);
267 
268 	mem->state = ret ? from_state_req : to_state;
269 
270 	return ret;
271 }
272 
273 /* The device lock serializes operations on memory_subsys_[online|offline] */
274 static int memory_subsys_online(struct device *dev)
275 {
276 	struct memory_block *mem = to_memory_block(dev);
277 	int ret;
278 
279 	if (mem->state == MEM_ONLINE)
280 		return 0;
281 
282 	/*
283 	 * If we are called from store_mem_state(), online_type will be
284 	 * set >= 0 Otherwise we were called from the device online
285 	 * attribute and need to set the online_type.
286 	 */
287 	if (mem->online_type < 0)
288 		mem->online_type = MMOP_ONLINE_KEEP;
289 
290 	/* Already under protection of mem_hotplug_begin() */
291 	ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
292 
293 	/* clear online_type */
294 	mem->online_type = -1;
295 
296 	return ret;
297 }
298 
299 static int memory_subsys_offline(struct device *dev)
300 {
301 	struct memory_block *mem = to_memory_block(dev);
302 
303 	if (mem->state == MEM_OFFLINE)
304 		return 0;
305 
306 	return memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
307 }
308 
309 static ssize_t
310 store_mem_state(struct device *dev,
311 		struct device_attribute *attr, const char *buf, size_t count)
312 {
313 	struct memory_block *mem = to_memory_block(dev);
314 	int ret, online_type;
315 
316 	ret = lock_device_hotplug_sysfs();
317 	if (ret)
318 		return ret;
319 
320 	if (sysfs_streq(buf, "online_kernel"))
321 		online_type = MMOP_ONLINE_KERNEL;
322 	else if (sysfs_streq(buf, "online_movable"))
323 		online_type = MMOP_ONLINE_MOVABLE;
324 	else if (sysfs_streq(buf, "online"))
325 		online_type = MMOP_ONLINE_KEEP;
326 	else if (sysfs_streq(buf, "offline"))
327 		online_type = MMOP_OFFLINE;
328 	else {
329 		ret = -EINVAL;
330 		goto err;
331 	}
332 
333 	/*
334 	 * Memory hotplug needs to hold mem_hotplug_begin() for probe to find
335 	 * the correct memory block to online before doing device_online(dev),
336 	 * which will take dev->mutex.  Take the lock early to prevent an
337 	 * inversion, memory_subsys_online() callbacks will be implemented by
338 	 * assuming it's already protected.
339 	 */
340 	mem_hotplug_begin();
341 
342 	switch (online_type) {
343 	case MMOP_ONLINE_KERNEL:
344 	case MMOP_ONLINE_MOVABLE:
345 	case MMOP_ONLINE_KEEP:
346 		mem->online_type = online_type;
347 		ret = device_online(&mem->dev);
348 		break;
349 	case MMOP_OFFLINE:
350 		ret = device_offline(&mem->dev);
351 		break;
352 	default:
353 		ret = -EINVAL; /* should never happen */
354 	}
355 
356 	mem_hotplug_done();
357 err:
358 	unlock_device_hotplug();
359 
360 	if (ret)
361 		return ret;
362 	return count;
363 }
364 
365 /*
366  * phys_device is a bad name for this.  What I really want
367  * is a way to differentiate between memory ranges that
368  * are part of physical devices that constitute
369  * a complete removable unit or fru.
370  * i.e. do these ranges belong to the same physical device,
371  * s.t. if I offline all of these sections I can then
372  * remove the physical device?
373  */
374 static ssize_t show_phys_device(struct device *dev,
375 				struct device_attribute *attr, char *buf)
376 {
377 	struct memory_block *mem = to_memory_block(dev);
378 	return sprintf(buf, "%d\n", mem->phys_device);
379 }
380 
381 #ifdef CONFIG_MEMORY_HOTREMOVE
382 static ssize_t show_valid_zones(struct device *dev,
383 				struct device_attribute *attr, char *buf)
384 {
385 	struct memory_block *mem = to_memory_block(dev);
386 	unsigned long start_pfn, end_pfn;
387 	unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
388 	struct page *first_page;
389 	struct zone *zone;
390 
391 	start_pfn = section_nr_to_pfn(mem->start_section_nr);
392 	end_pfn = start_pfn + nr_pages;
393 	first_page = pfn_to_page(start_pfn);
394 
395 	/* The block contains more than one zone can not be offlined. */
396 	if (!test_pages_in_a_zone(start_pfn, end_pfn))
397 		return sprintf(buf, "none\n");
398 
399 	zone = page_zone(first_page);
400 
401 	if (zone_idx(zone) == ZONE_MOVABLE - 1) {
402 		/*The mem block is the last memoryblock of this zone.*/
403 		if (end_pfn == zone_end_pfn(zone))
404 			return sprintf(buf, "%s %s\n",
405 					zone->name, (zone + 1)->name);
406 	}
407 
408 	if (zone_idx(zone) == ZONE_MOVABLE) {
409 		/*The mem block is the first memoryblock of ZONE_MOVABLE.*/
410 		if (start_pfn == zone->zone_start_pfn)
411 			return sprintf(buf, "%s %s\n",
412 					zone->name, (zone - 1)->name);
413 	}
414 
415 	return sprintf(buf, "%s\n", zone->name);
416 }
417 static DEVICE_ATTR(valid_zones, 0444, show_valid_zones, NULL);
418 #endif
419 
420 static DEVICE_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
421 static DEVICE_ATTR(state, 0644, show_mem_state, store_mem_state);
422 static DEVICE_ATTR(phys_device, 0444, show_phys_device, NULL);
423 static DEVICE_ATTR(removable, 0444, show_mem_removable, NULL);
424 
425 /*
426  * Block size attribute stuff
427  */
428 static ssize_t
429 print_block_size(struct device *dev, struct device_attribute *attr,
430 		 char *buf)
431 {
432 	return sprintf(buf, "%lx\n", get_memory_block_size());
433 }
434 
435 static DEVICE_ATTR(block_size_bytes, 0444, print_block_size, NULL);
436 
437 /*
438  * Some architectures will have custom drivers to do this, and
439  * will not need to do it from userspace.  The fake hot-add code
440  * as well as ppc64 will do all of their discovery in userspace
441  * and will require this interface.
442  */
443 #ifdef CONFIG_ARCH_MEMORY_PROBE
444 static ssize_t
445 memory_probe_store(struct device *dev, struct device_attribute *attr,
446 		   const char *buf, size_t count)
447 {
448 	u64 phys_addr;
449 	int nid;
450 	int i, ret;
451 	unsigned long pages_per_block = PAGES_PER_SECTION * sections_per_block;
452 
453 	ret = kstrtoull(buf, 0, &phys_addr);
454 	if (ret)
455 		return ret;
456 
457 	if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1))
458 		return -EINVAL;
459 
460 	for (i = 0; i < sections_per_block; i++) {
461 		nid = memory_add_physaddr_to_nid(phys_addr);
462 		ret = add_memory(nid, phys_addr,
463 				 PAGES_PER_SECTION << PAGE_SHIFT);
464 		if (ret)
465 			goto out;
466 
467 		phys_addr += MIN_MEMORY_BLOCK_SIZE;
468 	}
469 
470 	ret = count;
471 out:
472 	return ret;
473 }
474 
475 static DEVICE_ATTR(probe, S_IWUSR, NULL, memory_probe_store);
476 #endif
477 
478 #ifdef CONFIG_MEMORY_FAILURE
479 /*
480  * Support for offlining pages of memory
481  */
482 
483 /* Soft offline a page */
484 static ssize_t
485 store_soft_offline_page(struct device *dev,
486 			struct device_attribute *attr,
487 			const char *buf, size_t count)
488 {
489 	int ret;
490 	u64 pfn;
491 	if (!capable(CAP_SYS_ADMIN))
492 		return -EPERM;
493 	if (kstrtoull(buf, 0, &pfn) < 0)
494 		return -EINVAL;
495 	pfn >>= PAGE_SHIFT;
496 	if (!pfn_valid(pfn))
497 		return -ENXIO;
498 	ret = soft_offline_page(pfn_to_page(pfn), 0);
499 	return ret == 0 ? count : ret;
500 }
501 
502 /* Forcibly offline a page, including killing processes. */
503 static ssize_t
504 store_hard_offline_page(struct device *dev,
505 			struct device_attribute *attr,
506 			const char *buf, size_t count)
507 {
508 	int ret;
509 	u64 pfn;
510 	if (!capable(CAP_SYS_ADMIN))
511 		return -EPERM;
512 	if (kstrtoull(buf, 0, &pfn) < 0)
513 		return -EINVAL;
514 	pfn >>= PAGE_SHIFT;
515 	ret = memory_failure(pfn, 0, 0);
516 	return ret ? ret : count;
517 }
518 
519 static DEVICE_ATTR(soft_offline_page, S_IWUSR, NULL, store_soft_offline_page);
520 static DEVICE_ATTR(hard_offline_page, S_IWUSR, NULL, store_hard_offline_page);
521 #endif
522 
523 /*
524  * Note that phys_device is optional.  It is here to allow for
525  * differentiation between which *physical* devices each
526  * section belongs to...
527  */
528 int __weak arch_get_memory_phys_device(unsigned long start_pfn)
529 {
530 	return 0;
531 }
532 
533 /*
534  * A reference for the returned object is held and the reference for the
535  * hinted object is released.
536  */
537 struct memory_block *find_memory_block_hinted(struct mem_section *section,
538 					      struct memory_block *hint)
539 {
540 	int block_id = base_memory_block_id(__section_nr(section));
541 	struct device *hintdev = hint ? &hint->dev : NULL;
542 	struct device *dev;
543 
544 	dev = subsys_find_device_by_id(&memory_subsys, block_id, hintdev);
545 	if (hint)
546 		put_device(&hint->dev);
547 	if (!dev)
548 		return NULL;
549 	return to_memory_block(dev);
550 }
551 
552 /*
553  * For now, we have a linear search to go find the appropriate
554  * memory_block corresponding to a particular phys_index. If
555  * this gets to be a real problem, we can always use a radix
556  * tree or something here.
557  *
558  * This could be made generic for all device subsystems.
559  */
560 struct memory_block *find_memory_block(struct mem_section *section)
561 {
562 	return find_memory_block_hinted(section, NULL);
563 }
564 
565 static struct attribute *memory_memblk_attrs[] = {
566 	&dev_attr_phys_index.attr,
567 	&dev_attr_state.attr,
568 	&dev_attr_phys_device.attr,
569 	&dev_attr_removable.attr,
570 #ifdef CONFIG_MEMORY_HOTREMOVE
571 	&dev_attr_valid_zones.attr,
572 #endif
573 	NULL
574 };
575 
576 static struct attribute_group memory_memblk_attr_group = {
577 	.attrs = memory_memblk_attrs,
578 };
579 
580 static const struct attribute_group *memory_memblk_attr_groups[] = {
581 	&memory_memblk_attr_group,
582 	NULL,
583 };
584 
585 /*
586  * register_memory - Setup a sysfs device for a memory block
587  */
588 static
589 int register_memory(struct memory_block *memory)
590 {
591 	memory->dev.bus = &memory_subsys;
592 	memory->dev.id = memory->start_section_nr / sections_per_block;
593 	memory->dev.release = memory_block_release;
594 	memory->dev.groups = memory_memblk_attr_groups;
595 	memory->dev.offline = memory->state == MEM_OFFLINE;
596 
597 	return device_register(&memory->dev);
598 }
599 
600 static int init_memory_block(struct memory_block **memory,
601 			     struct mem_section *section, unsigned long state)
602 {
603 	struct memory_block *mem;
604 	unsigned long start_pfn;
605 	int scn_nr;
606 	int ret = 0;
607 
608 	mem = kzalloc(sizeof(*mem), GFP_KERNEL);
609 	if (!mem)
610 		return -ENOMEM;
611 
612 	scn_nr = __section_nr(section);
613 	mem->start_section_nr =
614 			base_memory_block_id(scn_nr) * sections_per_block;
615 	mem->end_section_nr = mem->start_section_nr + sections_per_block - 1;
616 	mem->state = state;
617 	mem->section_count++;
618 	start_pfn = section_nr_to_pfn(mem->start_section_nr);
619 	mem->phys_device = arch_get_memory_phys_device(start_pfn);
620 
621 	ret = register_memory(mem);
622 
623 	*memory = mem;
624 	return ret;
625 }
626 
627 static int add_memory_block(int base_section_nr)
628 {
629 	struct memory_block *mem;
630 	int i, ret, section_count = 0, section_nr;
631 
632 	for (i = base_section_nr;
633 	     (i < base_section_nr + sections_per_block) && i < NR_MEM_SECTIONS;
634 	     i++) {
635 		if (!present_section_nr(i))
636 			continue;
637 		if (section_count == 0)
638 			section_nr = i;
639 		section_count++;
640 	}
641 
642 	if (section_count == 0)
643 		return 0;
644 	ret = init_memory_block(&mem, __nr_to_section(section_nr), MEM_ONLINE);
645 	if (ret)
646 		return ret;
647 	mem->section_count = section_count;
648 	return 0;
649 }
650 
651 
652 /*
653  * need an interface for the VM to add new memory regions,
654  * but without onlining it.
655  */
656 int register_new_memory(int nid, struct mem_section *section)
657 {
658 	int ret = 0;
659 	struct memory_block *mem;
660 
661 	mutex_lock(&mem_sysfs_mutex);
662 
663 	mem = find_memory_block(section);
664 	if (mem) {
665 		mem->section_count++;
666 		put_device(&mem->dev);
667 	} else {
668 		ret = init_memory_block(&mem, section, MEM_OFFLINE);
669 		if (ret)
670 			goto out;
671 	}
672 
673 	if (mem->section_count == sections_per_block)
674 		ret = register_mem_sect_under_node(mem, nid);
675 out:
676 	mutex_unlock(&mem_sysfs_mutex);
677 	return ret;
678 }
679 
680 #ifdef CONFIG_MEMORY_HOTREMOVE
681 static void
682 unregister_memory(struct memory_block *memory)
683 {
684 	BUG_ON(memory->dev.bus != &memory_subsys);
685 
686 	/* drop the ref. we got in remove_memory_block() */
687 	put_device(&memory->dev);
688 	device_unregister(&memory->dev);
689 }
690 
691 static int remove_memory_block(unsigned long node_id,
692 			       struct mem_section *section, int phys_device)
693 {
694 	struct memory_block *mem;
695 
696 	mutex_lock(&mem_sysfs_mutex);
697 	mem = find_memory_block(section);
698 	unregister_mem_sect_under_nodes(mem, __section_nr(section));
699 
700 	mem->section_count--;
701 	if (mem->section_count == 0)
702 		unregister_memory(mem);
703 	else
704 		put_device(&mem->dev);
705 
706 	mutex_unlock(&mem_sysfs_mutex);
707 	return 0;
708 }
709 
710 int unregister_memory_section(struct mem_section *section)
711 {
712 	if (!present_section(section))
713 		return -EINVAL;
714 
715 	return remove_memory_block(0, section, 0);
716 }
717 #endif /* CONFIG_MEMORY_HOTREMOVE */
718 
719 /* return true if the memory block is offlined, otherwise, return false */
720 bool is_memblock_offlined(struct memory_block *mem)
721 {
722 	return mem->state == MEM_OFFLINE;
723 }
724 
725 static struct attribute *memory_root_attrs[] = {
726 #ifdef CONFIG_ARCH_MEMORY_PROBE
727 	&dev_attr_probe.attr,
728 #endif
729 
730 #ifdef CONFIG_MEMORY_FAILURE
731 	&dev_attr_soft_offline_page.attr,
732 	&dev_attr_hard_offline_page.attr,
733 #endif
734 
735 	&dev_attr_block_size_bytes.attr,
736 	NULL
737 };
738 
739 static struct attribute_group memory_root_attr_group = {
740 	.attrs = memory_root_attrs,
741 };
742 
743 static const struct attribute_group *memory_root_attr_groups[] = {
744 	&memory_root_attr_group,
745 	NULL,
746 };
747 
748 /*
749  * Initialize the sysfs support for memory devices...
750  */
751 int __init memory_dev_init(void)
752 {
753 	unsigned int i;
754 	int ret;
755 	int err;
756 	unsigned long block_sz;
757 
758 	ret = subsys_system_register(&memory_subsys, memory_root_attr_groups);
759 	if (ret)
760 		goto out;
761 
762 	block_sz = get_memory_block_size();
763 	sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
764 
765 	/*
766 	 * Create entries for memory sections that were found
767 	 * during boot and have been initialized
768 	 */
769 	mutex_lock(&mem_sysfs_mutex);
770 	for (i = 0; i < NR_MEM_SECTIONS; i += sections_per_block) {
771 		err = add_memory_block(i);
772 		if (!ret)
773 			ret = err;
774 	}
775 	mutex_unlock(&mem_sysfs_mutex);
776 
777 out:
778 	if (ret)
779 		printk(KERN_ERR "%s() failed: %d\n", __func__, ret);
780 	return ret;
781 }
782