memory.c 20.6 KB
Newer Older
1
// SPDX-License-Identifier: GPL-2.0
2
/*
3
 * Memory subsystem support
4
5
6
7
8
9
10
11
12
13
14
15
16
 *
 * Written by Matt Tolentino <matthew.e.tolentino@intel.com>
 *            Dave Hansen <haveblue@us.ibm.com>
 *
 * This file provides the necessary infrastructure to represent
 * a SPARSEMEM-memory-model system's physical memory in /sysfs.
 * All arch-independent code that assumes MEMORY_HOTPLUG requires
 * SPARSEMEM should be contained here, or in mm/memory_hotplug.c.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/topology.h>
17
#include <linux/capability.h>
18
19
20
21
#include <linux/device.h>
#include <linux/memory.h>
#include <linux/memory_hotplug.h>
#include <linux/mm.h>
22
#include <linux/mutex.h>
23
#include <linux/stat.h>
24
#include <linux/slab.h>
25

Arun Sharma's avatar
Arun Sharma committed
26
#include <linux/atomic.h>
27
#include <linux/uaccess.h>
28

29
30
static DEFINE_MUTEX(mem_sysfs_mutex);

31
#define MEMORY_CLASS_NAME	"memory"
32

33
34
#define to_memory_block(dev) container_of(dev, struct memory_block, dev)

35
36
37
38
39
40
static int sections_per_block;

static inline int base_memory_block_id(int section_nr)
{
	return section_nr / sections_per_block;
}
41

42
43
44
static int memory_subsys_online(struct device *dev);
static int memory_subsys_offline(struct device *dev);

45
static struct bus_type memory_subsys = {
46
	.name = MEMORY_CLASS_NAME,
47
	.dev_name = MEMORY_CLASS_NAME,
48
49
	.online = memory_subsys_online,
	.offline = memory_subsys_offline,
50
51
};

52
static BLOCKING_NOTIFIER_HEAD(memory_chain);
53

54
int register_memory_notifier(struct notifier_block *nb)
55
{
56
	return blocking_notifier_chain_register(&memory_chain, nb);
57
}
58
EXPORT_SYMBOL(register_memory_notifier);
59

60
void unregister_memory_notifier(struct notifier_block *nb)
61
{
62
	blocking_notifier_chain_unregister(&memory_chain, nb);
63
}
64
EXPORT_SYMBOL(unregister_memory_notifier);
65

66
67
68
69
70
71
72
73
74
75
76
77
78
79
static ATOMIC_NOTIFIER_HEAD(memory_isolate_chain);

int register_memory_isolate_notifier(struct notifier_block *nb)
{
	return atomic_notifier_chain_register(&memory_isolate_chain, nb);
}
EXPORT_SYMBOL(register_memory_isolate_notifier);

void unregister_memory_isolate_notifier(struct notifier_block *nb)
{
	atomic_notifier_chain_unregister(&memory_isolate_chain, nb);
}
EXPORT_SYMBOL(unregister_memory_isolate_notifier);

80
81
static void memory_block_release(struct device *dev)
{
82
	struct memory_block *mem = to_memory_block(dev);
83
84
85
86

	kfree(mem);
}

87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
unsigned long __weak memory_block_size_bytes(void)
{
	return MIN_MEMORY_BLOCK_SIZE;
}

static unsigned long get_memory_block_size(void)
{
	unsigned long block_sz;

	block_sz = memory_block_size_bytes();

	/* Validate blk_sz is a power of 2 and not less than section size */
	if ((block_sz & (block_sz - 1)) || (block_sz < MIN_MEMORY_BLOCK_SIZE)) {
		WARN_ON(1);
		block_sz = MIN_MEMORY_BLOCK_SIZE;
	}

	return block_sz;
}

107
108
109
110
111
/*
 * use this as the physical section index that this memsection
 * uses.
 */

112
113
static ssize_t show_mem_start_phys_index(struct device *dev,
			struct device_attribute *attr, char *buf)
114
{
115
	struct memory_block *mem = to_memory_block(dev);
116
117
118
119
120
121
	unsigned long phys_index;

	phys_index = mem->start_section_nr / sections_per_block;
	return sprintf(buf, "%08lx\n", phys_index);
}

122
123
124
/*
 * Show whether the section of memory is likely to be hot-removable
 */
125
126
static ssize_t show_mem_removable(struct device *dev,
			struct device_attribute *attr, char *buf)
127
{
128
129
	unsigned long i, pfn;
	int ret = 1;
130
	struct memory_block *mem = to_memory_block(dev);
131

132
133
134
	if (mem->state != MEM_ONLINE)
		goto out;

135
	for (i = 0; i < sections_per_block; i++) {
136
137
		if (!present_section_nr(mem->start_section_nr + i))
			continue;
138
		pfn = section_nr_to_pfn(mem->start_section_nr + i);
139
140
141
		ret &= is_mem_section_removable(pfn, PAGES_PER_SECTION);
	}

142
out:
143
144
145
	return sprintf(buf, "%d\n", ret);
}

146
147
148
/*
 * online, offline, going offline, etc.
 */
149
150
static ssize_t show_mem_state(struct device *dev,
			struct device_attribute *attr, char *buf)
151
{
152
	struct memory_block *mem = to_memory_block(dev);
153
154
155
156
157
158
159
	ssize_t len = 0;

	/*
	 * We can probably put these states in a nice little array
	 * so that they're not open-coded
	 */
	switch (mem->state) {
160
161
162
163
164
165
166
167
168
169
170
171
172
173
	case MEM_ONLINE:
		len = sprintf(buf, "online\n");
		break;
	case MEM_OFFLINE:
		len = sprintf(buf, "offline\n");
		break;
	case MEM_GOING_OFFLINE:
		len = sprintf(buf, "going-offline\n");
		break;
	default:
		len = sprintf(buf, "ERROR-UNKNOWN-%ld\n",
				mem->state);
		WARN_ON(1);
		break;
174
175
176
177
178
	}

	return len;
}

179
int memory_notify(unsigned long val, void *v)
180
{
181
	return blocking_notifier_call_chain(&memory_chain, val, v);
182
183
}

184
185
186
187
188
int memory_isolate_notify(unsigned long val, void *v)
{
	return atomic_notifier_call_chain(&memory_isolate_chain, val, v);
}

189
/*
190
191
192
 * The probe routines leave the pages uninitialized, just as the bootmem code
 * does. Make sure we do not access them, but instead use only information from
 * within sections.
193
 */
194
static bool pages_correctly_probed(unsigned long start_pfn)
195
{
196
197
	unsigned long section_nr = pfn_to_section_nr(start_pfn);
	unsigned long section_nr_end = section_nr + sections_per_block;
198
199
200
201
202
203
204
	unsigned long pfn = start_pfn;

	/*
	 * memmap between sections is not contiguous except with
	 * SPARSEMEM_VMEMMAP. We lookup the page once per section
	 * and assume memmap is contiguous within each section
	 */
205
	for (; section_nr < section_nr_end; section_nr++) {
206
207
208
		if (WARN_ON_ONCE(!pfn_valid(pfn)))
			return false;

209
210
211
212
213
214
215
216
217
218
219
		if (!present_section_nr(section_nr)) {
			pr_warn("section %ld pfn[%lx, %lx) not present",
				section_nr, pfn, pfn + PAGES_PER_SECTION);
			return false;
		} else if (!valid_section_nr(section_nr)) {
			pr_warn("section %ld pfn[%lx, %lx) no valid memmap",
				section_nr, pfn, pfn + PAGES_PER_SECTION);
			return false;
		} else if (online_section_nr(section_nr)) {
			pr_warn("section %ld pfn[%lx, %lx) is already online",
				section_nr, pfn, pfn + PAGES_PER_SECTION);
220
221
			return false;
		}
222
		pfn += PAGES_PER_SECTION;
223
224
225
226
227
	}

	return true;
}

228
229
230
/*
 * MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
 * OK to have direct references to sparsemem variables in here.
231
 * Must already be protected by mem_hotplug_begin().
232
233
 */
static int
234
memory_block_action(unsigned long phys_index, unsigned long action, int online_type)
235
{
236
	unsigned long start_pfn;
237
	unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
238
239
	int ret;

240
	start_pfn = section_nr_to_pfn(phys_index);
241

242
	switch (action) {
243
	case MEM_ONLINE:
244
		if (!pages_correctly_probed(start_pfn))
245
246
247
248
249
250
251
252
253
254
255
			return -EBUSY;

		ret = online_pages(start_pfn, nr_pages, online_type);
		break;
	case MEM_OFFLINE:
		ret = offline_pages(start_pfn, nr_pages);
		break;
	default:
		WARN(1, KERN_WARNING "%s(%ld, %ld) unknown action: "
		     "%ld\n", __func__, phys_index, action, action);
		ret = -EINVAL;
256
257
258
259
260
	}

	return ret;
}

261
static int memory_block_change_state(struct memory_block *mem,
262
		unsigned long to_state, unsigned long from_state_req)
263
{
264
	int ret = 0;
265

266
267
	if (mem->state != from_state_req)
		return -EINVAL;
268

269
270
271
	if (to_state == MEM_OFFLINE)
		mem->state = MEM_GOING_OFFLINE;

272
273
274
	ret = memory_block_action(mem->start_section_nr, to_state,
				mem->online_type);

275
	mem->state = ret ? from_state_req : to_state;
276

277
278
	return ret;
}
279

280
/* The device lock serializes operations on memory_subsys_[online|offline] */
281
282
static int memory_subsys_online(struct device *dev)
{
283
	struct memory_block *mem = to_memory_block(dev);
284
	int ret;
285

286
287
	if (mem->state == MEM_ONLINE)
		return 0;
288

289
290
291
292
293
294
	/*
	 * If we are called from store_mem_state(), online_type will be
	 * set >= 0 Otherwise we were called from the device online
	 * attribute and need to set the online_type.
	 */
	if (mem->online_type < 0)
295
		mem->online_type = MMOP_ONLINE_KEEP;
296

297
	/* Already under protection of mem_hotplug_begin() */
298
	ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
299

300
301
	/* clear online_type */
	mem->online_type = -1;
302
303
304
305
306

	return ret;
}

static int memory_subsys_offline(struct device *dev)
307
{
308
	struct memory_block *mem = to_memory_block(dev);
309

310
311
	if (mem->state == MEM_OFFLINE)
		return 0;
312

313
314
315
316
	/* Can't offline block with non-present sections */
	if (mem->section_count != sections_per_block)
		return -EINVAL;

317
	return memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
318
}
319

320
static ssize_t
321
322
store_mem_state(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t count)
323
{
324
	struct memory_block *mem = to_memory_block(dev);
325
	int ret, online_type;
326

327
328
329
	ret = lock_device_hotplug_sysfs();
	if (ret)
		return ret;
330

331
	if (sysfs_streq(buf, "online_kernel"))
332
		online_type = MMOP_ONLINE_KERNEL;
333
	else if (sysfs_streq(buf, "online_movable"))
334
		online_type = MMOP_ONLINE_MOVABLE;
335
	else if (sysfs_streq(buf, "online"))
336
		online_type = MMOP_ONLINE_KEEP;
337
	else if (sysfs_streq(buf, "offline"))
338
		online_type = MMOP_OFFLINE;
339
340
341
342
	else {
		ret = -EINVAL;
		goto err;
	}
343

344
345
346
347
348
349
350
351
352
	/*
	 * Memory hotplug needs to hold mem_hotplug_begin() for probe to find
	 * the correct memory block to online before doing device_online(dev),
	 * which will take dev->mutex.  Take the lock early to prevent an
	 * inversion, memory_subsys_online() callbacks will be implemented by
	 * assuming it's already protected.
	 */
	mem_hotplug_begin();

353
	switch (online_type) {
354
355
356
	case MMOP_ONLINE_KERNEL:
	case MMOP_ONLINE_MOVABLE:
	case MMOP_ONLINE_KEEP:
357
358
359
		mem->online_type = online_type;
		ret = device_online(&mem->dev);
		break;
360
	case MMOP_OFFLINE:
361
362
363
364
		ret = device_offline(&mem->dev);
		break;
	default:
		ret = -EINVAL; /* should never happen */
365
366
	}

367
	mem_hotplug_done();
368
err:
369
	unlock_device_hotplug();
370

371
	if (ret < 0)
372
		return ret;
373
374
375
	if (ret)
		return -EINVAL;

376
377
378
379
380
381
382
383
384
385
386
387
	return count;
}

/*
 * phys_device is a bad name for this.  What I really want
 * is a way to differentiate between memory ranges that
 * are part of physical devices that constitute
 * a complete removable unit or fru.
 * i.e. do these ranges belong to the same physical device,
 * s.t. if I offline all of these sections I can then
 * remove the physical device?
 */
388
389
static ssize_t show_phys_device(struct device *dev,
				struct device_attribute *attr, char *buf)
390
{
391
	struct memory_block *mem = to_memory_block(dev);
392
393
394
	return sprintf(buf, "%d\n", mem->phys_device);
}

395
#ifdef CONFIG_MEMORY_HOTREMOVE
396
397
398
399
400
401
402
403
404
405
406
407
408
static void print_allowed_zone(char *buf, int nid, unsigned long start_pfn,
		unsigned long nr_pages, int online_type,
		struct zone *default_zone)
{
	struct zone *zone;

	zone = zone_for_pfn_range(online_type, nid, start_pfn, nr_pages);
	if (zone != default_zone) {
		strcat(buf, " ");
		strcat(buf, zone->name);
	}
}

409
410
411
412
static ssize_t show_valid_zones(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	struct memory_block *mem = to_memory_block(dev);
413
	unsigned long start_pfn = section_nr_to_pfn(mem->start_section_nr);
414
	unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
415
	unsigned long valid_start_pfn, valid_end_pfn;
416
	struct zone *default_zone;
417
	int nid;
418

419
420
421
422
423
	/*
	 * The block contains more than one zone can not be offlined.
	 * This can happen e.g. for ZONE_DMA and ZONE_DMA32
	 */
	if (!test_pages_in_a_zone(start_pfn, start_pfn + nr_pages, &valid_start_pfn, &valid_end_pfn))
424
425
		return sprintf(buf, "none\n");

426
427
	start_pfn = valid_start_pfn;
	nr_pages = valid_end_pfn - start_pfn;
428

429
430
431
432
433
434
435
	/*
	 * Check the existing zone. Make sure that we do that only on the
	 * online nodes otherwise the page_zone is not reliable
	 */
	if (mem->state == MEM_ONLINE) {
		strcat(buf, page_zone(pfn_to_page(start_pfn))->name);
		goto out;
436
437
	}

438
	nid = pfn_to_nid(start_pfn);
439
440
	default_zone = zone_for_pfn_range(MMOP_ONLINE_KEEP, nid, start_pfn, nr_pages);
	strcat(buf, default_zone->name);
441

442
443
444
445
	print_allowed_zone(buf, nid, start_pfn, nr_pages, MMOP_ONLINE_KERNEL,
			default_zone);
	print_allowed_zone(buf, nid, start_pfn, nr_pages, MMOP_ONLINE_MOVABLE,
			default_zone);
446
out:
447
448
449
	strcat(buf, "\n");

	return strlen(buf);
450
451
452
453
}
static DEVICE_ATTR(valid_zones, 0444, show_valid_zones, NULL);
#endif

454
455
456
457
static DEVICE_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
static DEVICE_ATTR(state, 0644, show_mem_state, store_mem_state);
static DEVICE_ATTR(phys_device, 0444, show_phys_device, NULL);
static DEVICE_ATTR(removable, 0444, show_mem_removable, NULL);
458
459
460
461
462

/*
 * Block size attribute stuff
 */
static ssize_t
463
print_block_size(struct device *dev, struct device_attribute *attr,
464
		 char *buf)
465
{
466
	return sprintf(buf, "%lx\n", get_memory_block_size());
467
468
}

469
static DEVICE_ATTR(block_size_bytes, 0444, print_block_size, NULL);
470

471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
/*
 * Memory auto online policy.
 */

static ssize_t
show_auto_online_blocks(struct device *dev, struct device_attribute *attr,
			char *buf)
{
	if (memhp_auto_online)
		return sprintf(buf, "online\n");
	else
		return sprintf(buf, "offline\n");
}

static ssize_t
store_auto_online_blocks(struct device *dev, struct device_attribute *attr,
			 const char *buf, size_t count)
{
	if (sysfs_streq(buf, "online"))
		memhp_auto_online = true;
	else if (sysfs_streq(buf, "offline"))
		memhp_auto_online = false;
	else
		return -EINVAL;

	return count;
}

static DEVICE_ATTR(auto_online_blocks, 0644, show_auto_online_blocks,
		   store_auto_online_blocks);

502
503
504
505
506
507
508
509
/*
 * Some architectures will have custom drivers to do this, and
 * will not need to do it from userspace.  The fake hot-add code
 * as well as ppc64 will do all of their discovery in userspace
 * and will require this interface.
 */
#ifdef CONFIG_ARCH_MEMORY_PROBE
static ssize_t
510
memory_probe_store(struct device *dev, struct device_attribute *attr,
511
		   const char *buf, size_t count)
512
513
{
	u64 phys_addr;
514
	int nid, ret;
515
	unsigned long pages_per_block = PAGES_PER_SECTION * sections_per_block;
516

517
518
519
	ret = kstrtoull(buf, 0, &phys_addr);
	if (ret)
		return ret;
520

521
522
523
	if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1))
		return -EINVAL;

524
525
526
	nid = memory_add_physaddr_to_nid(phys_addr);
	ret = add_memory(nid, phys_addr,
			 MIN_MEMORY_BLOCK_SIZE * sections_per_block);
527

528
529
	if (ret)
		goto out;
530

531
532
533
	ret = count;
out:
	return ret;
534
535
}

536
static DEVICE_ATTR(probe, S_IWUSR, NULL, memory_probe_store);
537
538
#endif

539
540
541
542
543
544
545
#ifdef CONFIG_MEMORY_FAILURE
/*
 * Support for offlining pages of memory
 */

/* Soft offline a page */
static ssize_t
546
547
store_soft_offline_page(struct device *dev,
			struct device_attribute *attr,
548
			const char *buf, size_t count)
549
550
551
552
553
{
	int ret;
	u64 pfn;
	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;
554
	if (kstrtoull(buf, 0, &pfn) < 0)
555
556
557
558
559
560
561
562
563
564
		return -EINVAL;
	pfn >>= PAGE_SHIFT;
	if (!pfn_valid(pfn))
		return -ENXIO;
	ret = soft_offline_page(pfn_to_page(pfn), 0);
	return ret == 0 ? count : ret;
}

/* Forcibly offline a page, including killing processes. */
static ssize_t
565
566
store_hard_offline_page(struct device *dev,
			struct device_attribute *attr,
567
			const char *buf, size_t count)
568
569
570
571
572
{
	int ret;
	u64 pfn;
	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;
573
	if (kstrtoull(buf, 0, &pfn) < 0)
574
575
		return -EINVAL;
	pfn >>= PAGE_SHIFT;
576
	ret = memory_failure(pfn, 0);
577
578
579
	return ret ? ret : count;
}

580
581
static DEVICE_ATTR(soft_offline_page, S_IWUSR, NULL, store_soft_offline_page);
static DEVICE_ATTR(hard_offline_page, S_IWUSR, NULL, store_hard_offline_page);
582
583
#endif

584
585
586
587
588
/*
 * Note that phys_device is optional.  It is here to allow for
 * differentiation between which *physical* devices each
 * section belongs to...
 */
589
590
591
592
int __weak arch_get_memory_phys_device(unsigned long start_pfn)
{
	return 0;
}
593

594
595
596
597
/*
 * A reference for the returned object is held and the reference for the
 * hinted object is released.
 */
598
599
struct memory_block *find_memory_block_hinted(struct mem_section *section,
					      struct memory_block *hint)
600
{
601
	int block_id = base_memory_block_id(__section_nr(section));
602
603
	struct device *hintdev = hint ? &hint->dev : NULL;
	struct device *dev;
604

605
606
607
608
	dev = subsys_find_device_by_id(&memory_subsys, block_id, hintdev);
	if (hint)
		put_device(&hint->dev);
	if (!dev)
609
		return NULL;
610
	return to_memory_block(dev);
611
612
}

613
614
615
616
617
618
/*
 * For now, we have a linear search to go find the appropriate
 * memory_block corresponding to a particular phys_index. If
 * this gets to be a real problem, we can always use a radix
 * tree or something here.
 *
619
 * This could be made generic for all device subsystems.
620
621
622
623
624
625
 */
struct memory_block *find_memory_block(struct mem_section *section)
{
	return find_memory_block_hinted(section, NULL);
}

626
627
628
629
630
static struct attribute *memory_memblk_attrs[] = {
	&dev_attr_phys_index.attr,
	&dev_attr_state.attr,
	&dev_attr_phys_device.attr,
	&dev_attr_removable.attr,
631
632
633
#ifdef CONFIG_MEMORY_HOTREMOVE
	&dev_attr_valid_zones.attr,
#endif
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
	NULL
};

static struct attribute_group memory_memblk_attr_group = {
	.attrs = memory_memblk_attrs,
};

static const struct attribute_group *memory_memblk_attr_groups[] = {
	&memory_memblk_attr_group,
	NULL,
};

/*
 * register_memory - Setup a sysfs device for a memory block
 */
static
int register_memory(struct memory_block *memory)
{
	memory->dev.bus = &memory_subsys;
	memory->dev.id = memory->start_section_nr / sections_per_block;
	memory->dev.release = memory_block_release;
	memory->dev.groups = memory_memblk_attr_groups;
656
	memory->dev.offline = memory->state == MEM_OFFLINE;
657

658
	return device_register(&memory->dev);
659
660
}

661
662
static int init_memory_block(struct memory_block **memory,
			     struct mem_section *section, unsigned long state)
663
{
664
	struct memory_block *mem;
665
	unsigned long start_pfn;
666
	int scn_nr;
667
668
	int ret = 0;

669
	mem = kzalloc(sizeof(*mem), GFP_KERNEL);
670
671
672
	if (!mem)
		return -ENOMEM;

673
	scn_nr = __section_nr(section);
674
675
676
	mem->start_section_nr =
			base_memory_block_id(scn_nr) * sections_per_block;
	mem->end_section_nr = mem->start_section_nr + sections_per_block - 1;
677
	mem->state = state;
678
	start_pfn = section_nr_to_pfn(mem->start_section_nr);
679
680
	mem->phys_device = arch_get_memory_phys_device(start_pfn);

681
682
683
684
685
686
	ret = register_memory(mem);

	*memory = mem;
	return ret;
}

687
static int add_memory_block(int base_section_nr)
688
{
689
690
	struct memory_block *mem;
	int i, ret, section_count = 0, section_nr;
691

692
693
694
695
696
697
698
699
	for (i = base_section_nr;
	     (i < base_section_nr + sections_per_block) && i < NR_MEM_SECTIONS;
	     i++) {
		if (!present_section_nr(i))
			continue;
		if (section_count == 0)
			section_nr = i;
		section_count++;
700
701
	}

702
703
704
705
706
707
708
	if (section_count == 0)
		return 0;
	ret = init_memory_block(&mem, __nr_to_section(section_nr), MEM_ONLINE);
	if (ret)
		return ret;
	mem->section_count = section_count;
	return 0;
709
710
}

711
712
713
714
/*
 * need an interface for the VM to add new memory regions,
 * but without onlining it.
 */
715
int hotplug_memory_register(int nid, struct mem_section *section)
716
{
717
718
	int ret = 0;
	struct memory_block *mem;
719
720
721

	mutex_lock(&mem_sysfs_mutex);

722
723
724
725
726
727
728
729
	mem = find_memory_block(section);
	if (mem) {
		mem->section_count++;
		put_device(&mem->dev);
	} else {
		ret = init_memory_block(&mem, section, MEM_OFFLINE);
		if (ret)
			goto out;
730
		mem->section_count++;
731
732
733
	}

	if (mem->section_count == sections_per_block)
734
		ret = register_mem_sect_under_node(mem, nid, false);
735
736
out:
	mutex_unlock(&mem_sysfs_mutex);
737
	return ret;
738
739
740
741
742
743
744
745
746
}

#ifdef CONFIG_MEMORY_HOTREMOVE
static void
unregister_memory(struct memory_block *memory)
{
	BUG_ON(memory->dev.bus != &memory_subsys);

	/* drop the ref. we got in remove_memory_block() */
747
	put_device(&memory->dev);
748
749
750
	device_unregister(&memory->dev);
}

751
static int remove_memory_section(unsigned long node_id,
752
			       struct mem_section *section, int phys_device)
753
754
755
{
	struct memory_block *mem;

756
	mutex_lock(&mem_sysfs_mutex);
757
758
759
760
761

	/*
	 * Some users of the memory hotplug do not want/need memblock to
	 * track all sections. Skip over those.
	 */
762
	mem = find_memory_block(section);
763
764
765
	if (!mem)
		goto out_unlock;

766
	unregister_mem_sect_under_nodes(mem, __section_nr(section));
767
768

	mem->section_count--;
769
	if (mem->section_count == 0)
770
		unregister_memory(mem);
771
	else
772
		put_device(&mem->dev);
773

774
out_unlock:
775
	mutex_unlock(&mem_sysfs_mutex);
776
777
778
779
780
	return 0;
}

int unregister_memory_section(struct mem_section *section)
{
781
	if (!present_section(section))
782
783
		return -EINVAL;

784
	return remove_memory_section(0, section, 0);
785
}
786
#endif /* CONFIG_MEMORY_HOTREMOVE */
787

788
789
790
791
792
793
/* return true if the memory block is offlined, otherwise, return false */
bool is_memblock_offlined(struct memory_block *mem)
{
	return mem->state == MEM_OFFLINE;
}

794
795
796
797
798
799
800
801
802
803
804
static struct attribute *memory_root_attrs[] = {
#ifdef CONFIG_ARCH_MEMORY_PROBE
	&dev_attr_probe.attr,
#endif

#ifdef CONFIG_MEMORY_FAILURE
	&dev_attr_soft_offline_page.attr,
	&dev_attr_hard_offline_page.attr,
#endif

	&dev_attr_block_size_bytes.attr,
805
	&dev_attr_auto_online_blocks.attr,
806
807
808
809
810
811
812
813
814
815
816
817
	NULL
};

static struct attribute_group memory_root_attr_group = {
	.attrs = memory_root_attrs,
};

static const struct attribute_group *memory_root_attr_groups[] = {
	&memory_root_attr_group,
	NULL,
};

818
819
820
821
822
823
824
/*
 * Initialize the sysfs support for memory devices...
 */
int __init memory_dev_init(void)
{
	unsigned int i;
	int ret;
825
	int err;
826
	unsigned long block_sz;
827

828
	ret = subsys_system_register(&memory_subsys, memory_root_attr_groups);
829
830
	if (ret)
		goto out;
831

832
833
834
	block_sz = get_memory_block_size();
	sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;

835
836
837
838
	/*
	 * Create entries for memory sections that were found
	 * during boot and have been initialized
	 */
839
	mutex_lock(&mem_sysfs_mutex);
840
	for (i = 0; i < NR_MEM_SECTIONS; i += sections_per_block) {
841
842
843
844
		/* Don't iterate over sections we know are !present: */
		if (i > __highest_present_section_nr)
			break;

845
		err = add_memory_block(i);
846
847
		if (!ret)
			ret = err;
848
	}
849
	mutex_unlock(&mem_sysfs_mutex);
850

851
852
out:
	if (ret)
853
		printk(KERN_ERR "%s() failed: %d\n", __func__, ret);
854
855
	return ret;
}