1 /*
2  *  linux/mm/memory_hotplug.c
3  *
4  *  Copyright (C)
5  */
6 
7 #include <linux/stddef.h>
8 #include <linux/mm.h>
9 #include <linux/sched/signal.h>
10 #include <linux/swap.h>
11 #include <linux/interrupt.h>
12 #include <linux/pagemap.h>
13 #include <linux/compiler.h>
14 #include <linux/export.h>
15 #include <linux/pagevec.h>
16 #include <linux/writeback.h>
17 #include <linux/slab.h>
18 #include <linux/sysctl.h>
19 #include <linux/cpu.h>
20 #include <linux/memory.h>
21 #include <linux/memremap.h>
22 #include <linux/memory_hotplug.h>
23 #include <linux/highmem.h>
24 #include <linux/vmalloc.h>
25 #include <linux/ioport.h>
26 #include <linux/delay.h>
27 #include <linux/migrate.h>
28 #include <linux/page-isolation.h>
29 #include <linux/pfn.h>
30 #include <linux/suspend.h>
31 #include <linux/mm_inline.h>
32 #include <linux/firmware-map.h>
33 #include <linux/stop_machine.h>
34 #include <linux/hugetlb.h>
35 #include <linux/memblock.h>
36 #include <linux/bootmem.h>
37 #include <linux/compaction.h>
38 
39 #include <asm/tlbflush.h>
40 
41 #include "internal.h"
42 
43 /*
44  * online_page_callback contains pointer to current page onlining function.
45  * Initially it is generic_online_page(). If it is required it could be
46  * changed by calling set_online_page_callback() for callback registration
47  * and restore_online_page_callback() for generic callback restore.
48  */
49 
50 static void generic_online_page(struct page *page);
51 
52 static online_page_callback_t online_page_callback = generic_online_page;
53 static DEFINE_MUTEX(online_page_callback_lock);
54 
55 DEFINE_STATIC_PERCPU_RWSEM(mem_hotplug_lock);
56 
get_online_mems(void)57 void get_online_mems(void)
58 {
59 	percpu_down_read(&mem_hotplug_lock);
60 }
61 
put_online_mems(void)62 void put_online_mems(void)
63 {
64 	percpu_up_read(&mem_hotplug_lock);
65 }
66 
67 bool movable_node_enabled = false;
68 
69 #ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
70 bool memhp_auto_online;
71 #else
72 bool memhp_auto_online = true;
73 #endif
74 EXPORT_SYMBOL_GPL(memhp_auto_online);
75 
setup_memhp_default_state(char * str)76 static int __init setup_memhp_default_state(char *str)
77 {
78 	if (!strcmp(str, "online"))
79 		memhp_auto_online = true;
80 	else if (!strcmp(str, "offline"))
81 		memhp_auto_online = false;
82 
83 	return 1;
84 }
85 __setup("memhp_default_state=", setup_memhp_default_state);
86 
mem_hotplug_begin(void)87 void mem_hotplug_begin(void)
88 {
89 	cpus_read_lock();
90 	percpu_down_write(&mem_hotplug_lock);
91 }
92 
mem_hotplug_done(void)93 void mem_hotplug_done(void)
94 {
95 	percpu_up_write(&mem_hotplug_lock);
96 	cpus_read_unlock();
97 }
98 
99 /* add this memory to iomem resource */
register_memory_resource(u64 start,u64 size)100 static struct resource *register_memory_resource(u64 start, u64 size)
101 {
102 	struct resource *res, *conflict;
103 	res = kzalloc(sizeof(struct resource), GFP_KERNEL);
104 	if (!res)
105 		return ERR_PTR(-ENOMEM);
106 
107 	res->name = "System RAM";
108 	res->start = start;
109 	res->end = start + size - 1;
110 	res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
111 	conflict =  request_resource_conflict(&iomem_resource, res);
112 	if (conflict) {
113 		if (conflict->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY) {
114 			pr_debug("Device unaddressable memory block "
115 				 "memory hotplug at %#010llx !\n",
116 				 (unsigned long long)start);
117 		}
118 		pr_debug("System RAM resource %pR cannot be added\n", res);
119 		kfree(res);
120 		return ERR_PTR(-EEXIST);
121 	}
122 	return res;
123 }
124 
release_memory_resource(struct resource * res)125 static void release_memory_resource(struct resource *res)
126 {
127 	if (!res)
128 		return;
129 	release_resource(res);
130 	kfree(res);
131 	return;
132 }
133 
134 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
get_page_bootmem(unsigned long info,struct page * page,unsigned long type)135 void get_page_bootmem(unsigned long info,  struct page *page,
136 		      unsigned long type)
137 {
138 	page->freelist = (void *)type;
139 	SetPagePrivate(page);
140 	set_page_private(page, info);
141 	page_ref_inc(page);
142 }
143 
put_page_bootmem(struct page * page)144 void put_page_bootmem(struct page *page)
145 {
146 	unsigned long type;
147 
148 	type = (unsigned long) page->freelist;
149 	BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
150 	       type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE);
151 
152 	if (page_ref_dec_return(page) == 1) {
153 		page->freelist = NULL;
154 		ClearPagePrivate(page);
155 		set_page_private(page, 0);
156 		INIT_LIST_HEAD(&page->lru);
157 		free_reserved_page(page);
158 	}
159 }
160 
161 #ifdef CONFIG_HAVE_BOOTMEM_INFO_NODE
162 #ifndef CONFIG_SPARSEMEM_VMEMMAP
register_page_bootmem_info_section(unsigned long start_pfn)163 static void register_page_bootmem_info_section(unsigned long start_pfn)
164 {
165 	unsigned long *usemap, mapsize, section_nr, i;
166 	struct mem_section *ms;
167 	struct page *page, *memmap;
168 
169 	section_nr = pfn_to_section_nr(start_pfn);
170 	ms = __nr_to_section(section_nr);
171 
172 	/* Get section's memmap address */
173 	memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
174 
175 	/*
176 	 * Get page for the memmap's phys address
177 	 * XXX: need more consideration for sparse_vmemmap...
178 	 */
179 	page = virt_to_page(memmap);
180 	mapsize = sizeof(struct page) * PAGES_PER_SECTION;
181 	mapsize = PAGE_ALIGN(mapsize) >> PAGE_SHIFT;
182 
183 	/* remember memmap's page */
184 	for (i = 0; i < mapsize; i++, page++)
185 		get_page_bootmem(section_nr, page, SECTION_INFO);
186 
187 	usemap = ms->pageblock_flags;
188 	page = virt_to_page(usemap);
189 
190 	mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT;
191 
192 	for (i = 0; i < mapsize; i++, page++)
193 		get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
194 
195 }
196 #else /* CONFIG_SPARSEMEM_VMEMMAP */
register_page_bootmem_info_section(unsigned long start_pfn)197 static void register_page_bootmem_info_section(unsigned long start_pfn)
198 {
199 	unsigned long *usemap, mapsize, section_nr, i;
200 	struct mem_section *ms;
201 	struct page *page, *memmap;
202 
203 	section_nr = pfn_to_section_nr(start_pfn);
204 	ms = __nr_to_section(section_nr);
205 
206 	memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
207 
208 	register_page_bootmem_memmap(section_nr, memmap, PAGES_PER_SECTION);
209 
210 	usemap = ms->pageblock_flags;
211 	page = virt_to_page(usemap);
212 
213 	mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT;
214 
215 	for (i = 0; i < mapsize; i++, page++)
216 		get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
217 }
218 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
219 
register_page_bootmem_info_node(struct pglist_data * pgdat)220 void __init register_page_bootmem_info_node(struct pglist_data *pgdat)
221 {
222 	unsigned long i, pfn, end_pfn, nr_pages;
223 	int node = pgdat->node_id;
224 	struct page *page;
225 
226 	nr_pages = PAGE_ALIGN(sizeof(struct pglist_data)) >> PAGE_SHIFT;
227 	page = virt_to_page(pgdat);
228 
229 	for (i = 0; i < nr_pages; i++, page++)
230 		get_page_bootmem(node, page, NODE_INFO);
231 
232 	pfn = pgdat->node_start_pfn;
233 	end_pfn = pgdat_end_pfn(pgdat);
234 
235 	/* register section info */
236 	for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
237 		/*
238 		 * Some platforms can assign the same pfn to multiple nodes - on
239 		 * node0 as well as nodeN.  To avoid registering a pfn against
240 		 * multiple nodes we check that this pfn does not already
241 		 * reside in some other nodes.
242 		 */
243 		if (pfn_valid(pfn) && (early_pfn_to_nid(pfn) == node))
244 			register_page_bootmem_info_section(pfn);
245 	}
246 }
247 #endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */
248 
__add_section(int nid,unsigned long phys_start_pfn,struct vmem_altmap * altmap,bool want_memblock)249 static int __meminit __add_section(int nid, unsigned long phys_start_pfn,
250 		struct vmem_altmap *altmap, bool want_memblock)
251 {
252 	int ret;
253 
254 	if (pfn_valid(phys_start_pfn))
255 		return -EEXIST;
256 
257 	ret = sparse_add_one_section(NODE_DATA(nid), phys_start_pfn, altmap);
258 	if (ret < 0)
259 		return ret;
260 
261 	if (!want_memblock)
262 		return 0;
263 
264 	return hotplug_memory_register(nid, __pfn_to_section(phys_start_pfn));
265 }
266 
267 /*
268  * Reasonably generic function for adding memory.  It is
269  * expected that archs that support memory hotplug will
270  * call this function after deciding the zone to which to
271  * add the new pages.
272  */
__add_pages(int nid,unsigned long phys_start_pfn,unsigned long nr_pages,struct vmem_altmap * altmap,bool want_memblock)273 int __ref __add_pages(int nid, unsigned long phys_start_pfn,
274 		unsigned long nr_pages, struct vmem_altmap *altmap,
275 		bool want_memblock)
276 {
277 	unsigned long i;
278 	int err = 0;
279 	int start_sec, end_sec;
280 
281 	/* during initialize mem_map, align hot-added range to section */
282 	start_sec = pfn_to_section_nr(phys_start_pfn);
283 	end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
284 
285 	if (altmap) {
286 		/*
287 		 * Validate altmap is within bounds of the total request
288 		 */
289 		if (altmap->base_pfn != phys_start_pfn
290 				|| vmem_altmap_offset(altmap) > nr_pages) {
291 			pr_warn_once("memory add fail, invalid altmap\n");
292 			err = -EINVAL;
293 			goto out;
294 		}
295 		altmap->alloc = 0;
296 	}
297 
298 	for (i = start_sec; i <= end_sec; i++) {
299 		err = __add_section(nid, section_nr_to_pfn(i), altmap,
300 				want_memblock);
301 
302 		/*
303 		 * EEXIST is finally dealt with by ioresource collision
304 		 * check. see add_memory() => register_memory_resource()
305 		 * Warning will be printed if there is collision.
306 		 */
307 		if (err && (err != -EEXIST))
308 			break;
309 		err = 0;
310 		cond_resched();
311 	}
312 	vmemmap_populate_print_last();
313 out:
314 	return err;
315 }
316 
317 #ifdef CONFIG_MEMORY_HOTREMOVE
318 /* find the smallest valid pfn in the range [start_pfn, end_pfn) */
find_smallest_section_pfn(int nid,struct zone * zone,unsigned long start_pfn,unsigned long end_pfn)319 static unsigned long find_smallest_section_pfn(int nid, struct zone *zone,
320 				     unsigned long start_pfn,
321 				     unsigned long end_pfn)
322 {
323 	struct mem_section *ms;
324 
325 	for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SECTION) {
326 		ms = __pfn_to_section(start_pfn);
327 
328 		if (unlikely(!valid_section(ms)))
329 			continue;
330 
331 		if (unlikely(pfn_to_nid(start_pfn) != nid))
332 			continue;
333 
334 		if (zone && zone != page_zone(pfn_to_page(start_pfn)))
335 			continue;
336 
337 		return start_pfn;
338 	}
339 
340 	return 0;
341 }
342 
343 /* find the biggest valid pfn in the range [start_pfn, end_pfn). */
find_biggest_section_pfn(int nid,struct zone * zone,unsigned long start_pfn,unsigned long end_pfn)344 static unsigned long find_biggest_section_pfn(int nid, struct zone *zone,
345 				    unsigned long start_pfn,
346 				    unsigned long end_pfn)
347 {
348 	struct mem_section *ms;
349 	unsigned long pfn;
350 
351 	/* pfn is the end pfn of a memory section. */
352 	pfn = end_pfn - 1;
353 	for (; pfn >= start_pfn; pfn -= PAGES_PER_SECTION) {
354 		ms = __pfn_to_section(pfn);
355 
356 		if (unlikely(!valid_section(ms)))
357 			continue;
358 
359 		if (unlikely(pfn_to_nid(pfn) != nid))
360 			continue;
361 
362 		if (zone && zone != page_zone(pfn_to_page(pfn)))
363 			continue;
364 
365 		return pfn;
366 	}
367 
368 	return 0;
369 }
370 
shrink_zone_span(struct zone * zone,unsigned long start_pfn,unsigned long end_pfn)371 static void shrink_zone_span(struct zone *zone, unsigned long start_pfn,
372 			     unsigned long end_pfn)
373 {
374 	unsigned long zone_start_pfn = zone->zone_start_pfn;
375 	unsigned long z = zone_end_pfn(zone); /* zone_end_pfn namespace clash */
376 	unsigned long zone_end_pfn = z;
377 	unsigned long pfn;
378 	struct mem_section *ms;
379 	int nid = zone_to_nid(zone);
380 
381 	zone_span_writelock(zone);
382 	if (zone_start_pfn == start_pfn) {
383 		/*
384 		 * If the section is smallest section in the zone, it need
385 		 * shrink zone->zone_start_pfn and zone->zone_spanned_pages.
386 		 * In this case, we find second smallest valid mem_section
387 		 * for shrinking zone.
388 		 */
389 		pfn = find_smallest_section_pfn(nid, zone, end_pfn,
390 						zone_end_pfn);
391 		if (pfn) {
392 			zone->zone_start_pfn = pfn;
393 			zone->spanned_pages = zone_end_pfn - pfn;
394 		}
395 	} else if (zone_end_pfn == end_pfn) {
396 		/*
397 		 * If the section is biggest section in the zone, it need
398 		 * shrink zone->spanned_pages.
399 		 * In this case, we find second biggest valid mem_section for
400 		 * shrinking zone.
401 		 */
402 		pfn = find_biggest_section_pfn(nid, zone, zone_start_pfn,
403 					       start_pfn);
404 		if (pfn)
405 			zone->spanned_pages = pfn - zone_start_pfn + 1;
406 	}
407 
408 	/*
409 	 * The section is not biggest or smallest mem_section in the zone, it
410 	 * only creates a hole in the zone. So in this case, we need not
411 	 * change the zone. But perhaps, the zone has only hole data. Thus
412 	 * it check the zone has only hole or not.
413 	 */
414 	pfn = zone_start_pfn;
415 	for (; pfn < zone_end_pfn; pfn += PAGES_PER_SECTION) {
416 		ms = __pfn_to_section(pfn);
417 
418 		if (unlikely(!valid_section(ms)))
419 			continue;
420 
421 		if (page_zone(pfn_to_page(pfn)) != zone)
422 			continue;
423 
424 		 /* If the section is current section, it continues the loop */
425 		if (start_pfn == pfn)
426 			continue;
427 
428 		/* If we find valid section, we have nothing to do */
429 		zone_span_writeunlock(zone);
430 		return;
431 	}
432 
433 	/* The zone has no valid section */
434 	zone->zone_start_pfn = 0;
435 	zone->spanned_pages = 0;
436 	zone_span_writeunlock(zone);
437 }
438 
shrink_pgdat_span(struct pglist_data * pgdat,unsigned long start_pfn,unsigned long end_pfn)439 static void shrink_pgdat_span(struct pglist_data *pgdat,
440 			      unsigned long start_pfn, unsigned long end_pfn)
441 {
442 	unsigned long pgdat_start_pfn = pgdat->node_start_pfn;
443 	unsigned long p = pgdat_end_pfn(pgdat); /* pgdat_end_pfn namespace clash */
444 	unsigned long pgdat_end_pfn = p;
445 	unsigned long pfn;
446 	struct mem_section *ms;
447 	int nid = pgdat->node_id;
448 
449 	if (pgdat_start_pfn == start_pfn) {
450 		/*
451 		 * If the section is smallest section in the pgdat, it need
452 		 * shrink pgdat->node_start_pfn and pgdat->node_spanned_pages.
453 		 * In this case, we find second smallest valid mem_section
454 		 * for shrinking zone.
455 		 */
456 		pfn = find_smallest_section_pfn(nid, NULL, end_pfn,
457 						pgdat_end_pfn);
458 		if (pfn) {
459 			pgdat->node_start_pfn = pfn;
460 			pgdat->node_spanned_pages = pgdat_end_pfn - pfn;
461 		}
462 	} else if (pgdat_end_pfn == end_pfn) {
463 		/*
464 		 * If the section is biggest section in the pgdat, it need
465 		 * shrink pgdat->node_spanned_pages.
466 		 * In this case, we find second biggest valid mem_section for
467 		 * shrinking zone.
468 		 */
469 		pfn = find_biggest_section_pfn(nid, NULL, pgdat_start_pfn,
470 					       start_pfn);
471 		if (pfn)
472 			pgdat->node_spanned_pages = pfn - pgdat_start_pfn + 1;
473 	}
474 
475 	/*
476 	 * If the section is not biggest or smallest mem_section in the pgdat,
477 	 * it only creates a hole in the pgdat. So in this case, we need not
478 	 * change the pgdat.
479 	 * But perhaps, the pgdat has only hole data. Thus it check the pgdat
480 	 * has only hole or not.
481 	 */
482 	pfn = pgdat_start_pfn;
483 	for (; pfn < pgdat_end_pfn; pfn += PAGES_PER_SECTION) {
484 		ms = __pfn_to_section(pfn);
485 
486 		if (unlikely(!valid_section(ms)))
487 			continue;
488 
489 		if (pfn_to_nid(pfn) != nid)
490 			continue;
491 
492 		 /* If the section is current section, it continues the loop */
493 		if (start_pfn == pfn)
494 			continue;
495 
496 		/* If we find valid section, we have nothing to do */
497 		return;
498 	}
499 
500 	/* The pgdat has no valid section */
501 	pgdat->node_start_pfn = 0;
502 	pgdat->node_spanned_pages = 0;
503 }
504 
__remove_zone(struct zone * zone,unsigned long start_pfn)505 static void __remove_zone(struct zone *zone, unsigned long start_pfn)
506 {
507 	struct pglist_data *pgdat = zone->zone_pgdat;
508 	int nr_pages = PAGES_PER_SECTION;
509 	unsigned long flags;
510 
511 	pgdat_resize_lock(zone->zone_pgdat, &flags);
512 	shrink_zone_span(zone, start_pfn, start_pfn + nr_pages);
513 	shrink_pgdat_span(pgdat, start_pfn, start_pfn + nr_pages);
514 	pgdat_resize_unlock(zone->zone_pgdat, &flags);
515 }
516 
__remove_section(struct zone * zone,struct mem_section * ms,unsigned long map_offset,struct vmem_altmap * altmap)517 static int __remove_section(struct zone *zone, struct mem_section *ms,
518 		unsigned long map_offset, struct vmem_altmap *altmap)
519 {
520 	unsigned long start_pfn;
521 	int scn_nr;
522 	int ret = -EINVAL;
523 
524 	if (!valid_section(ms))
525 		return ret;
526 
527 	ret = unregister_memory_section(ms);
528 	if (ret)
529 		return ret;
530 
531 	scn_nr = __section_nr(ms);
532 	start_pfn = section_nr_to_pfn((unsigned long)scn_nr);
533 	__remove_zone(zone, start_pfn);
534 
535 	sparse_remove_one_section(zone, ms, map_offset, altmap);
536 	return 0;
537 }
538 
539 /**
540  * __remove_pages() - remove sections of pages from a zone
541  * @zone: zone from which pages need to be removed
542  * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
543  * @nr_pages: number of pages to remove (must be multiple of section size)
544  * @altmap: alternative device page map or %NULL if default memmap is used
545  *
546  * Generic helper function to remove section mappings and sysfs entries
547  * for the section of the memory we are removing. Caller needs to make
548  * sure that pages are marked reserved and zones are adjust properly by
549  * calling offline_pages().
550  */
__remove_pages(struct zone * zone,unsigned long phys_start_pfn,unsigned long nr_pages,struct vmem_altmap * altmap)551 int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
552 		 unsigned long nr_pages, struct vmem_altmap *altmap)
553 {
554 	unsigned long i;
555 	unsigned long map_offset = 0;
556 	int sections_to_remove, ret = 0;
557 
558 	/* In the ZONE_DEVICE case device driver owns the memory region */
559 	if (is_dev_zone(zone)) {
560 		if (altmap)
561 			map_offset = vmem_altmap_offset(altmap);
562 	} else {
563 		resource_size_t start, size;
564 
565 		start = phys_start_pfn << PAGE_SHIFT;
566 		size = nr_pages * PAGE_SIZE;
567 
568 		ret = release_mem_region_adjustable(&iomem_resource, start,
569 					size);
570 		if (ret) {
571 			resource_size_t endres = start + size - 1;
572 
573 			pr_warn("Unable to release resource <%pa-%pa> (%d)\n",
574 					&start, &endres, ret);
575 		}
576 	}
577 
578 	clear_zone_contiguous(zone);
579 
580 	/*
581 	 * We can only remove entire sections
582 	 */
583 	BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
584 	BUG_ON(nr_pages % PAGES_PER_SECTION);
585 
586 	sections_to_remove = nr_pages / PAGES_PER_SECTION;
587 	for (i = 0; i < sections_to_remove; i++) {
588 		unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
589 
590 		ret = __remove_section(zone, __pfn_to_section(pfn), map_offset,
591 				altmap);
592 		map_offset = 0;
593 		if (ret)
594 			break;
595 	}
596 
597 	set_zone_contiguous(zone);
598 
599 	return ret;
600 }
601 #endif /* CONFIG_MEMORY_HOTREMOVE */
602 
set_online_page_callback(online_page_callback_t callback)603 int set_online_page_callback(online_page_callback_t callback)
604 {
605 	int rc = -EINVAL;
606 
607 	get_online_mems();
608 	mutex_lock(&online_page_callback_lock);
609 
610 	if (online_page_callback == generic_online_page) {
611 		online_page_callback = callback;
612 		rc = 0;
613 	}
614 
615 	mutex_unlock(&online_page_callback_lock);
616 	put_online_mems();
617 
618 	return rc;
619 }
620 EXPORT_SYMBOL_GPL(set_online_page_callback);
621 
restore_online_page_callback(online_page_callback_t callback)622 int restore_online_page_callback(online_page_callback_t callback)
623 {
624 	int rc = -EINVAL;
625 
626 	get_online_mems();
627 	mutex_lock(&online_page_callback_lock);
628 
629 	if (online_page_callback == callback) {
630 		online_page_callback = generic_online_page;
631 		rc = 0;
632 	}
633 
634 	mutex_unlock(&online_page_callback_lock);
635 	put_online_mems();
636 
637 	return rc;
638 }
639 EXPORT_SYMBOL_GPL(restore_online_page_callback);
640 
__online_page_set_limits(struct page * page)641 void __online_page_set_limits(struct page *page)
642 {
643 }
644 EXPORT_SYMBOL_GPL(__online_page_set_limits);
645 
__online_page_increment_counters(struct page * page)646 void __online_page_increment_counters(struct page *page)
647 {
648 	adjust_managed_page_count(page, 1);
649 }
650 EXPORT_SYMBOL_GPL(__online_page_increment_counters);
651 
__online_page_free(struct page * page)652 void __online_page_free(struct page *page)
653 {
654 	__free_reserved_page(page);
655 }
656 EXPORT_SYMBOL_GPL(__online_page_free);
657 
generic_online_page(struct page * page)658 static void generic_online_page(struct page *page)
659 {
660 	__online_page_set_limits(page);
661 	__online_page_increment_counters(page);
662 	__online_page_free(page);
663 }
664 
online_pages_range(unsigned long start_pfn,unsigned long nr_pages,void * arg)665 static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
666 			void *arg)
667 {
668 	unsigned long i;
669 	unsigned long onlined_pages = *(unsigned long *)arg;
670 	struct page *page;
671 
672 	if (PageReserved(pfn_to_page(start_pfn)))
673 		for (i = 0; i < nr_pages; i++) {
674 			page = pfn_to_page(start_pfn + i);
675 			(*online_page_callback)(page);
676 			onlined_pages++;
677 		}
678 
679 	online_mem_sections(start_pfn, start_pfn + nr_pages);
680 
681 	*(unsigned long *)arg = onlined_pages;
682 	return 0;
683 }
684 
685 /* check which state of node_states will be changed when online memory */
node_states_check_changes_online(unsigned long nr_pages,struct zone * zone,struct memory_notify * arg)686 static void node_states_check_changes_online(unsigned long nr_pages,
687 	struct zone *zone, struct memory_notify *arg)
688 {
689 	int nid = zone_to_nid(zone);
690 	enum zone_type zone_last = ZONE_NORMAL;
691 
692 	/*
693 	 * If we have HIGHMEM or movable node, node_states[N_NORMAL_MEMORY]
694 	 * contains nodes which have zones of 0...ZONE_NORMAL,
695 	 * set zone_last to ZONE_NORMAL.
696 	 *
697 	 * If we don't have HIGHMEM nor movable node,
698 	 * node_states[N_NORMAL_MEMORY] contains nodes which have zones of
699 	 * 0...ZONE_MOVABLE, set zone_last to ZONE_MOVABLE.
700 	 */
701 	if (N_MEMORY == N_NORMAL_MEMORY)
702 		zone_last = ZONE_MOVABLE;
703 
704 	/*
705 	 * if the memory to be online is in a zone of 0...zone_last, and
706 	 * the zones of 0...zone_last don't have memory before online, we will
707 	 * need to set the node to node_states[N_NORMAL_MEMORY] after
708 	 * the memory is online.
709 	 */
710 	if (zone_idx(zone) <= zone_last && !node_state(nid, N_NORMAL_MEMORY))
711 		arg->status_change_nid_normal = nid;
712 	else
713 		arg->status_change_nid_normal = -1;
714 
715 #ifdef CONFIG_HIGHMEM
716 	/*
717 	 * If we have movable node, node_states[N_HIGH_MEMORY]
718 	 * contains nodes which have zones of 0...ZONE_HIGHMEM,
719 	 * set zone_last to ZONE_HIGHMEM.
720 	 *
721 	 * If we don't have movable node, node_states[N_NORMAL_MEMORY]
722 	 * contains nodes which have zones of 0...ZONE_MOVABLE,
723 	 * set zone_last to ZONE_MOVABLE.
724 	 */
725 	zone_last = ZONE_HIGHMEM;
726 	if (N_MEMORY == N_HIGH_MEMORY)
727 		zone_last = ZONE_MOVABLE;
728 
729 	if (zone_idx(zone) <= zone_last && !node_state(nid, N_HIGH_MEMORY))
730 		arg->status_change_nid_high = nid;
731 	else
732 		arg->status_change_nid_high = -1;
733 #else
734 	arg->status_change_nid_high = arg->status_change_nid_normal;
735 #endif
736 
737 	/*
738 	 * if the node don't have memory befor online, we will need to
739 	 * set the node to node_states[N_MEMORY] after the memory
740 	 * is online.
741 	 */
742 	if (!node_state(nid, N_MEMORY))
743 		arg->status_change_nid = nid;
744 	else
745 		arg->status_change_nid = -1;
746 }
747 
node_states_set_node(int node,struct memory_notify * arg)748 static void node_states_set_node(int node, struct memory_notify *arg)
749 {
750 	if (arg->status_change_nid_normal >= 0)
751 		node_set_state(node, N_NORMAL_MEMORY);
752 
753 	if (arg->status_change_nid_high >= 0)
754 		node_set_state(node, N_HIGH_MEMORY);
755 
756 	node_set_state(node, N_MEMORY);
757 }
758 
resize_zone_range(struct zone * zone,unsigned long start_pfn,unsigned long nr_pages)759 static void __meminit resize_zone_range(struct zone *zone, unsigned long start_pfn,
760 		unsigned long nr_pages)
761 {
762 	unsigned long old_end_pfn = zone_end_pfn(zone);
763 
764 	if (zone_is_empty(zone) || start_pfn < zone->zone_start_pfn)
765 		zone->zone_start_pfn = start_pfn;
766 
767 	zone->spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - zone->zone_start_pfn;
768 }
769 
resize_pgdat_range(struct pglist_data * pgdat,unsigned long start_pfn,unsigned long nr_pages)770 static void __meminit resize_pgdat_range(struct pglist_data *pgdat, unsigned long start_pfn,
771                                      unsigned long nr_pages)
772 {
773 	unsigned long old_end_pfn = pgdat_end_pfn(pgdat);
774 
775 	if (!pgdat->node_spanned_pages || start_pfn < pgdat->node_start_pfn)
776 		pgdat->node_start_pfn = start_pfn;
777 
778 	pgdat->node_spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - pgdat->node_start_pfn;
779 }
780 
move_pfn_range_to_zone(struct zone * zone,unsigned long start_pfn,unsigned long nr_pages,struct vmem_altmap * altmap)781 void __ref move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
782 		unsigned long nr_pages, struct vmem_altmap *altmap)
783 {
784 	struct pglist_data *pgdat = zone->zone_pgdat;
785 	int nid = pgdat->node_id;
786 	unsigned long flags;
787 
788 	if (zone_is_empty(zone))
789 		init_currently_empty_zone(zone, start_pfn, nr_pages);
790 
791 	clear_zone_contiguous(zone);
792 
793 	/* TODO Huh pgdat is irqsave while zone is not. It used to be like that before */
794 	pgdat_resize_lock(pgdat, &flags);
795 	zone_span_writelock(zone);
796 	resize_zone_range(zone, start_pfn, nr_pages);
797 	zone_span_writeunlock(zone);
798 	resize_pgdat_range(pgdat, start_pfn, nr_pages);
799 	pgdat_resize_unlock(pgdat, &flags);
800 
801 	/*
802 	 * TODO now we have a visible range of pages which are not associated
803 	 * with their zone properly. Not nice but set_pfnblock_flags_mask
804 	 * expects the zone spans the pfn range. All the pages in the range
805 	 * are reserved so nobody should be touching them so we should be safe
806 	 */
807 	memmap_init_zone(nr_pages, nid, zone_idx(zone), start_pfn,
808 			MEMMAP_HOTPLUG, altmap);
809 
810 	set_zone_contiguous(zone);
811 }
812 
813 /*
814  * Returns a default kernel memory zone for the given pfn range.
815  * If no kernel zone covers this pfn range it will automatically go
816  * to the ZONE_NORMAL.
817  */
default_kernel_zone_for_pfn(int nid,unsigned long start_pfn,unsigned long nr_pages)818 static struct zone *default_kernel_zone_for_pfn(int nid, unsigned long start_pfn,
819 		unsigned long nr_pages)
820 {
821 	struct pglist_data *pgdat = NODE_DATA(nid);
822 	int zid;
823 
824 	for (zid = 0; zid <= ZONE_NORMAL; zid++) {
825 		struct zone *zone = &pgdat->node_zones[zid];
826 
827 		if (zone_intersects(zone, start_pfn, nr_pages))
828 			return zone;
829 	}
830 
831 	return &pgdat->node_zones[ZONE_NORMAL];
832 }
833 
default_zone_for_pfn(int nid,unsigned long start_pfn,unsigned long nr_pages)834 static inline struct zone *default_zone_for_pfn(int nid, unsigned long start_pfn,
835 		unsigned long nr_pages)
836 {
837 	struct zone *kernel_zone = default_kernel_zone_for_pfn(nid, start_pfn,
838 			nr_pages);
839 	struct zone *movable_zone = &NODE_DATA(nid)->node_zones[ZONE_MOVABLE];
840 	bool in_kernel = zone_intersects(kernel_zone, start_pfn, nr_pages);
841 	bool in_movable = zone_intersects(movable_zone, start_pfn, nr_pages);
842 
843 	/*
844 	 * We inherit the existing zone in a simple case where zones do not
845 	 * overlap in the given range
846 	 */
847 	if (in_kernel ^ in_movable)
848 		return (in_kernel) ? kernel_zone : movable_zone;
849 
850 	/*
851 	 * If the range doesn't belong to any zone or two zones overlap in the
852 	 * given range then we use movable zone only if movable_node is
853 	 * enabled because we always online to a kernel zone by default.
854 	 */
855 	return movable_node_enabled ? movable_zone : kernel_zone;
856 }
857 
zone_for_pfn_range(int online_type,int nid,unsigned start_pfn,unsigned long nr_pages)858 struct zone * zone_for_pfn_range(int online_type, int nid, unsigned start_pfn,
859 		unsigned long nr_pages)
860 {
861 	if (online_type == MMOP_ONLINE_KERNEL)
862 		return default_kernel_zone_for_pfn(nid, start_pfn, nr_pages);
863 
864 	if (online_type == MMOP_ONLINE_MOVABLE)
865 		return &NODE_DATA(nid)->node_zones[ZONE_MOVABLE];
866 
867 	return default_zone_for_pfn(nid, start_pfn, nr_pages);
868 }
869 
870 /*
871  * Associates the given pfn range with the given node and the zone appropriate
872  * for the given online type.
873  */
move_pfn_range(int online_type,int nid,unsigned long start_pfn,unsigned long nr_pages)874 static struct zone * __meminit move_pfn_range(int online_type, int nid,
875 		unsigned long start_pfn, unsigned long nr_pages)
876 {
877 	struct zone *zone;
878 
879 	zone = zone_for_pfn_range(online_type, nid, start_pfn, nr_pages);
880 	move_pfn_range_to_zone(zone, start_pfn, nr_pages, NULL);
881 	return zone;
882 }
883 
884 /* Must be protected by mem_hotplug_begin() or a device_lock */
online_pages(unsigned long pfn,unsigned long nr_pages,int online_type)885 int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_type)
886 {
887 	unsigned long flags;
888 	unsigned long onlined_pages = 0;
889 	struct zone *zone;
890 	int need_zonelists_rebuild = 0;
891 	int nid;
892 	int ret;
893 	struct memory_notify arg;
894 	struct memory_block *mem;
895 
896 	/*
897 	 * We can't use pfn_to_nid() because nid might be stored in struct page
898 	 * which is not yet initialized. Instead, we find nid from memory block.
899 	 */
900 	mem = find_memory_block(__pfn_to_section(pfn));
901 	nid = mem->nid;
902 
903 	/* associate pfn range with the zone */
904 	zone = move_pfn_range(online_type, nid, pfn, nr_pages);
905 
906 	arg.start_pfn = pfn;
907 	arg.nr_pages = nr_pages;
908 	node_states_check_changes_online(nr_pages, zone, &arg);
909 
910 	ret = memory_notify(MEM_GOING_ONLINE, &arg);
911 	ret = notifier_to_errno(ret);
912 	if (ret)
913 		goto failed_addition;
914 
915 	/*
916 	 * If this zone is not populated, then it is not in zonelist.
917 	 * This means the page allocator ignores this zone.
918 	 * So, zonelist must be updated after online.
919 	 */
920 	if (!populated_zone(zone)) {
921 		need_zonelists_rebuild = 1;
922 		setup_zone_pageset(zone);
923 	}
924 
925 	ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages,
926 		online_pages_range);
927 	if (ret) {
928 		if (need_zonelists_rebuild)
929 			zone_pcp_reset(zone);
930 		goto failed_addition;
931 	}
932 
933 	zone->present_pages += onlined_pages;
934 
935 	pgdat_resize_lock(zone->zone_pgdat, &flags);
936 	zone->zone_pgdat->node_present_pages += onlined_pages;
937 	pgdat_resize_unlock(zone->zone_pgdat, &flags);
938 
939 	if (onlined_pages) {
940 		node_states_set_node(nid, &arg);
941 		if (need_zonelists_rebuild)
942 			build_all_zonelists(NULL);
943 		else
944 			zone_pcp_update(zone);
945 	}
946 
947 	init_per_zone_wmark_min();
948 
949 	if (onlined_pages) {
950 		kswapd_run(nid);
951 		kcompactd_run(nid);
952 	}
953 
954 	vm_total_pages = nr_free_pagecache_pages();
955 
956 	writeback_set_ratelimit();
957 
958 	if (onlined_pages)
959 		memory_notify(MEM_ONLINE, &arg);
960 	return 0;
961 
962 failed_addition:
963 	pr_debug("online_pages [mem %#010llx-%#010llx] failed\n",
964 		 (unsigned long long) pfn << PAGE_SHIFT,
965 		 (((unsigned long long) pfn + nr_pages) << PAGE_SHIFT) - 1);
966 	memory_notify(MEM_CANCEL_ONLINE, &arg);
967 	return ret;
968 }
969 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
970 
reset_node_present_pages(pg_data_t * pgdat)971 static void reset_node_present_pages(pg_data_t *pgdat)
972 {
973 	struct zone *z;
974 
975 	for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
976 		z->present_pages = 0;
977 
978 	pgdat->node_present_pages = 0;
979 }
980 
981 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
hotadd_new_pgdat(int nid,u64 start)982 static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
983 {
984 	struct pglist_data *pgdat;
985 	unsigned long start_pfn = PFN_DOWN(start);
986 
987 	pgdat = NODE_DATA(nid);
988 	if (!pgdat) {
989 		pgdat = arch_alloc_nodedata(nid);
990 		if (!pgdat)
991 			return NULL;
992 
993 		arch_refresh_nodedata(nid, pgdat);
994 	} else {
995 		/*
996 		 * Reset the nr_zones, order and classzone_idx before reuse.
997 		 * Note that kswapd will init kswapd_classzone_idx properly
998 		 * when it starts in the near future.
999 		 */
1000 		pgdat->nr_zones = 0;
1001 		pgdat->kswapd_order = 0;
1002 		pgdat->kswapd_classzone_idx = 0;
1003 	}
1004 
1005 	/* we can use NODE_DATA(nid) from here */
1006 
1007 	pgdat->node_id = nid;
1008 	pgdat->node_start_pfn = start_pfn;
1009 
1010 	/* init node's zones as empty zones, we don't have any present pages.*/
1011 	free_area_init_core_hotplug(nid);
1012 	pgdat->per_cpu_nodestats = alloc_percpu(struct per_cpu_nodestat);
1013 
1014 	/*
1015 	 * The node we allocated has no zone fallback lists. For avoiding
1016 	 * to access not-initialized zonelist, build here.
1017 	 */
1018 	build_all_zonelists(pgdat);
1019 
1020 	/*
1021 	 * When memory is hot-added, all the memory is in offline state. So
1022 	 * clear all zones' present_pages because they will be updated in
1023 	 * online_pages() and offline_pages().
1024 	 */
1025 	reset_node_managed_pages(pgdat);
1026 	reset_node_present_pages(pgdat);
1027 
1028 	return pgdat;
1029 }
1030 
rollback_node_hotadd(int nid)1031 static void rollback_node_hotadd(int nid)
1032 {
1033 	pg_data_t *pgdat = NODE_DATA(nid);
1034 
1035 	arch_refresh_nodedata(nid, NULL);
1036 	free_percpu(pgdat->per_cpu_nodestats);
1037 	arch_free_nodedata(pgdat);
1038 	return;
1039 }
1040 
1041 
1042 /**
1043  * try_online_node - online a node if offlined
1044  * @nid: the node ID
1045  * @start: start addr of the node
1046  * @set_node_online: Whether we want to online the node
1047  * called by cpu_up() to online a node without onlined memory.
1048  *
1049  * Returns:
1050  * 1 -> a new node has been allocated
1051  * 0 -> the node is already online
1052  * -ENOMEM -> the node could not be allocated
1053  */
__try_online_node(int nid,u64 start,bool set_node_online)1054 static int __try_online_node(int nid, u64 start, bool set_node_online)
1055 {
1056 	pg_data_t *pgdat;
1057 	int ret = 1;
1058 
1059 	if (node_online(nid))
1060 		return 0;
1061 
1062 	pgdat = hotadd_new_pgdat(nid, start);
1063 	if (!pgdat) {
1064 		pr_err("Cannot online node %d due to NULL pgdat\n", nid);
1065 		ret = -ENOMEM;
1066 		goto out;
1067 	}
1068 
1069 	if (set_node_online) {
1070 		node_set_online(nid);
1071 		ret = register_one_node(nid);
1072 		BUG_ON(ret);
1073 	}
1074 out:
1075 	return ret;
1076 }
1077 
1078 /*
1079  * Users of this function always want to online/register the node
1080  */
try_online_node(int nid)1081 int try_online_node(int nid)
1082 {
1083 	int ret;
1084 
1085 	mem_hotplug_begin();
1086 	ret =  __try_online_node(nid, 0, true);
1087 	mem_hotplug_done();
1088 	return ret;
1089 }
1090 
check_hotplug_memory_range(u64 start,u64 size)1091 static int check_hotplug_memory_range(u64 start, u64 size)
1092 {
1093 	unsigned long block_sz = memory_block_size_bytes();
1094 	u64 block_nr_pages = block_sz >> PAGE_SHIFT;
1095 	u64 nr_pages = size >> PAGE_SHIFT;
1096 	u64 start_pfn = PFN_DOWN(start);
1097 
1098 	/* memory range must be block size aligned */
1099 	if (!nr_pages || !IS_ALIGNED(start_pfn, block_nr_pages) ||
1100 	    !IS_ALIGNED(nr_pages, block_nr_pages)) {
1101 		pr_err("Block size [%#lx] unaligned hotplug range: start %#llx, size %#llx",
1102 		       block_sz, start, size);
1103 		return -EINVAL;
1104 	}
1105 
1106 	return 0;
1107 }
1108 
online_memory_block(struct memory_block * mem,void * arg)1109 static int online_memory_block(struct memory_block *mem, void *arg)
1110 {
1111 	return device_online(&mem->dev);
1112 }
1113 
1114 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
add_memory_resource(int nid,struct resource * res,bool online)1115 int __ref add_memory_resource(int nid, struct resource *res, bool online)
1116 {
1117 	u64 start, size;
1118 	bool new_node = false;
1119 	int ret;
1120 
1121 	start = res->start;
1122 	size = resource_size(res);
1123 
1124 	ret = check_hotplug_memory_range(start, size);
1125 	if (ret)
1126 		return ret;
1127 
1128 	mem_hotplug_begin();
1129 
1130 	/*
1131 	 * Add new range to memblock so that when hotadd_new_pgdat() is called
1132 	 * to allocate new pgdat, get_pfn_range_for_nid() will be able to find
1133 	 * this new range and calculate total pages correctly.  The range will
1134 	 * be removed at hot-remove time.
1135 	 */
1136 	memblock_add_node(start, size, nid);
1137 
1138 	ret = __try_online_node(nid, start, false);
1139 	if (ret < 0)
1140 		goto error;
1141 	new_node = ret;
1142 
1143 	/* call arch's memory hotadd */
1144 	ret = arch_add_memory(nid, start, size, NULL, true);
1145 	if (ret < 0)
1146 		goto error;
1147 
1148 	if (new_node) {
1149 		/* If sysfs file of new node can't be created, cpu on the node
1150 		 * can't be hot-added. There is no rollback way now.
1151 		 * So, check by BUG_ON() to catch it reluctantly..
1152 		 * We online node here. We can't roll back from here.
1153 		 */
1154 		node_set_online(nid);
1155 		ret = __register_one_node(nid);
1156 		BUG_ON(ret);
1157 	}
1158 
1159 	/* link memory sections under this node.*/
1160 	ret = link_mem_sections(nid, PFN_DOWN(start), PFN_UP(start + size - 1));
1161 	BUG_ON(ret);
1162 
1163 	/* create new memmap entry */
1164 	firmware_map_add_hotplug(start, start + size, "System RAM");
1165 
1166 	/* online pages if requested */
1167 	if (online)
1168 		walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1),
1169 				  NULL, online_memory_block);
1170 
1171 	goto out;
1172 
1173 error:
1174 	/* rollback pgdat allocation and others */
1175 	if (new_node)
1176 		rollback_node_hotadd(nid);
1177 	memblock_remove(start, size);
1178 
1179 out:
1180 	mem_hotplug_done();
1181 	return ret;
1182 }
1183 EXPORT_SYMBOL_GPL(add_memory_resource);
1184 
add_memory(int nid,u64 start,u64 size)1185 int __ref add_memory(int nid, u64 start, u64 size)
1186 {
1187 	struct resource *res;
1188 	int ret;
1189 
1190 	res = register_memory_resource(start, size);
1191 	if (IS_ERR(res))
1192 		return PTR_ERR(res);
1193 
1194 	ret = add_memory_resource(nid, res, memhp_auto_online);
1195 	if (ret < 0)
1196 		release_memory_resource(res);
1197 	return ret;
1198 }
1199 EXPORT_SYMBOL_GPL(add_memory);
1200 
1201 #ifdef CONFIG_MEMORY_HOTREMOVE
1202 /*
1203  * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
1204  * set and the size of the free page is given by page_order(). Using this,
1205  * the function determines if the pageblock contains only free pages.
1206  * Due to buddy contraints, a free page at least the size of a pageblock will
1207  * be located at the start of the pageblock
1208  */
pageblock_free(struct page * page)1209 static inline int pageblock_free(struct page *page)
1210 {
1211 	return PageBuddy(page) && page_order(page) >= pageblock_order;
1212 }
1213 
1214 /* Return the start of the next active pageblock after a given page */
next_active_pageblock(struct page * page)1215 static struct page *next_active_pageblock(struct page *page)
1216 {
1217 	/* Ensure the starting page is pageblock-aligned */
1218 	BUG_ON(page_to_pfn(page) & (pageblock_nr_pages - 1));
1219 
1220 	/* If the entire pageblock is free, move to the end of free page */
1221 	if (pageblock_free(page)) {
1222 		int order;
1223 		/* be careful. we don't have locks, page_order can be changed.*/
1224 		order = page_order(page);
1225 		if ((order < MAX_ORDER) && (order >= pageblock_order))
1226 			return page + (1 << order);
1227 	}
1228 
1229 	return page + pageblock_nr_pages;
1230 }
1231 
is_pageblock_removable_nolock(struct page * page)1232 static bool is_pageblock_removable_nolock(struct page *page)
1233 {
1234 	struct zone *zone;
1235 	unsigned long pfn;
1236 
1237 	/*
1238 	 * We have to be careful here because we are iterating over memory
1239 	 * sections which are not zone aware so we might end up outside of
1240 	 * the zone but still within the section.
1241 	 * We have to take care about the node as well. If the node is offline
1242 	 * its NODE_DATA will be NULL - see page_zone.
1243 	 */
1244 	if (!node_online(page_to_nid(page)))
1245 		return false;
1246 
1247 	zone = page_zone(page);
1248 	pfn = page_to_pfn(page);
1249 	if (!zone_spans_pfn(zone, pfn))
1250 		return false;
1251 
1252 	return !has_unmovable_pages(zone, page, 0, MIGRATE_MOVABLE, true);
1253 }
1254 
1255 /* Checks if this range of memory is likely to be hot-removable. */
is_mem_section_removable(unsigned long start_pfn,unsigned long nr_pages)1256 bool is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
1257 {
1258 	struct page *page = pfn_to_page(start_pfn);
1259 	struct page *end_page = page + nr_pages;
1260 
1261 	/* Check the starting page of each pageblock within the range */
1262 	for (; page < end_page; page = next_active_pageblock(page)) {
1263 		if (!is_pageblock_removable_nolock(page))
1264 			return false;
1265 		cond_resched();
1266 	}
1267 
1268 	/* All pageblocks in the memory block are likely to be hot-removable */
1269 	return true;
1270 }
1271 
1272 /*
1273  * Confirm all pages in a range [start, end) belong to the same zone.
1274  * When true, return its valid [start, end).
1275  */
test_pages_in_a_zone(unsigned long start_pfn,unsigned long end_pfn,unsigned long * valid_start,unsigned long * valid_end)1276 int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn,
1277 			 unsigned long *valid_start, unsigned long *valid_end)
1278 {
1279 	unsigned long pfn, sec_end_pfn;
1280 	unsigned long start, end;
1281 	struct zone *zone = NULL;
1282 	struct page *page;
1283 	int i;
1284 	for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn + 1);
1285 	     pfn < end_pfn;
1286 	     pfn = sec_end_pfn, sec_end_pfn += PAGES_PER_SECTION) {
1287 		/* Make sure the memory section is present first */
1288 		if (!present_section_nr(pfn_to_section_nr(pfn)))
1289 			continue;
1290 		for (; pfn < sec_end_pfn && pfn < end_pfn;
1291 		     pfn += MAX_ORDER_NR_PAGES) {
1292 			i = 0;
1293 			/* This is just a CONFIG_HOLES_IN_ZONE check.*/
1294 			while ((i < MAX_ORDER_NR_PAGES) &&
1295 				!pfn_valid_within(pfn + i))
1296 				i++;
1297 			if (i == MAX_ORDER_NR_PAGES || pfn + i >= end_pfn)
1298 				continue;
1299 			page = pfn_to_page(pfn + i);
1300 			if (zone && page_zone(page) != zone)
1301 				return 0;
1302 			if (!zone)
1303 				start = pfn + i;
1304 			zone = page_zone(page);
1305 			end = pfn + MAX_ORDER_NR_PAGES;
1306 		}
1307 	}
1308 
1309 	if (zone) {
1310 		*valid_start = start;
1311 		*valid_end = min(end, end_pfn);
1312 		return 1;
1313 	} else {
1314 		return 0;
1315 	}
1316 }
1317 
1318 /*
1319  * Scan pfn range [start,end) to find movable/migratable pages (LRU pages,
1320  * non-lru movable pages and hugepages). We scan pfn because it's much
1321  * easier than scanning over linked list. This function returns the pfn
1322  * of the first found movable page if it's found, otherwise 0.
1323  */
scan_movable_pages(unsigned long start,unsigned long end)1324 static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
1325 {
1326 	unsigned long pfn;
1327 	struct page *page;
1328 	for (pfn = start; pfn < end; pfn++) {
1329 		if (pfn_valid(pfn)) {
1330 			page = pfn_to_page(pfn);
1331 			if (PageLRU(page))
1332 				return pfn;
1333 			if (__PageMovable(page))
1334 				return pfn;
1335 			if (PageHuge(page)) {
1336 				if (hugepage_migration_supported(page_hstate(page)) &&
1337 				    page_huge_active(page))
1338 					return pfn;
1339 				else
1340 					pfn = round_up(pfn + 1,
1341 						1 << compound_order(page)) - 1;
1342 			}
1343 		}
1344 	}
1345 	return 0;
1346 }
1347 
new_node_page(struct page * page,unsigned long private)1348 static struct page *new_node_page(struct page *page, unsigned long private)
1349 {
1350 	int nid = page_to_nid(page);
1351 	nodemask_t nmask = node_states[N_MEMORY];
1352 
1353 	/*
1354 	 * try to allocate from a different node but reuse this node if there
1355 	 * are no other online nodes to be used (e.g. we are offlining a part
1356 	 * of the only existing node)
1357 	 */
1358 	node_clear(nid, nmask);
1359 	if (nodes_empty(nmask))
1360 		node_set(nid, nmask);
1361 
1362 	return new_page_nodemask(page, nid, &nmask);
1363 }
1364 
1365 #define NR_OFFLINE_AT_ONCE_PAGES	(256)
1366 static int
do_migrate_range(unsigned long start_pfn,unsigned long end_pfn)1367 do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
1368 {
1369 	unsigned long pfn;
1370 	struct page *page;
1371 	int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
1372 	int not_managed = 0;
1373 	int ret = 0;
1374 	LIST_HEAD(source);
1375 
1376 	for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
1377 		if (!pfn_valid(pfn))
1378 			continue;
1379 		page = pfn_to_page(pfn);
1380 
1381 		if (PageHuge(page)) {
1382 			struct page *head = compound_head(page);
1383 			pfn = page_to_pfn(head) + (1<<compound_order(head)) - 1;
1384 			if (compound_order(head) > PFN_SECTION_SHIFT) {
1385 				ret = -EBUSY;
1386 				break;
1387 			}
1388 			if (isolate_huge_page(page, &source))
1389 				move_pages -= 1 << compound_order(head);
1390 			continue;
1391 		} else if (PageTransHuge(page))
1392 			pfn = page_to_pfn(compound_head(page))
1393 				+ hpage_nr_pages(page) - 1;
1394 
1395 		if (!get_page_unless_zero(page))
1396 			continue;
1397 		/*
1398 		 * We can skip free pages. And we can deal with pages on
1399 		 * LRU and non-lru movable pages.
1400 		 */
1401 		if (PageLRU(page))
1402 			ret = isolate_lru_page(page);
1403 		else
1404 			ret = isolate_movable_page(page, ISOLATE_UNEVICTABLE);
1405 		if (!ret) { /* Success */
1406 			put_page(page);
1407 			list_add_tail(&page->lru, &source);
1408 			move_pages--;
1409 			if (!__PageMovable(page))
1410 				inc_node_page_state(page, NR_ISOLATED_ANON +
1411 						    page_is_file_cache(page));
1412 
1413 		} else {
1414 #ifdef CONFIG_DEBUG_VM
1415 			pr_alert("failed to isolate pfn %lx\n", pfn);
1416 			dump_page(page, "isolation failed");
1417 #endif
1418 			put_page(page);
1419 			/* Because we don't have big zone->lock. we should
1420 			   check this again here. */
1421 			if (page_count(page)) {
1422 				not_managed++;
1423 				ret = -EBUSY;
1424 				break;
1425 			}
1426 		}
1427 	}
1428 	if (!list_empty(&source)) {
1429 		if (not_managed) {
1430 			putback_movable_pages(&source);
1431 			goto out;
1432 		}
1433 
1434 		/* Allocate a new page from the nearest neighbor node */
1435 		ret = migrate_pages(&source, new_node_page, NULL, 0,
1436 					MIGRATE_SYNC, MR_MEMORY_HOTPLUG);
1437 		if (ret)
1438 			putback_movable_pages(&source);
1439 	}
1440 out:
1441 	return ret;
1442 }
1443 
1444 /*
1445  * remove from free_area[] and mark all as Reserved.
1446  */
1447 static int
offline_isolated_pages_cb(unsigned long start,unsigned long nr_pages,void * data)1448 offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
1449 			void *data)
1450 {
1451 	__offline_isolated_pages(start, start + nr_pages);
1452 	return 0;
1453 }
1454 
1455 static void
offline_isolated_pages(unsigned long start_pfn,unsigned long end_pfn)1456 offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
1457 {
1458 	walk_system_ram_range(start_pfn, end_pfn - start_pfn, NULL,
1459 				offline_isolated_pages_cb);
1460 }
1461 
1462 /*
1463  * Check all pages in range, recoreded as memory resource, are isolated.
1464  */
1465 static int
check_pages_isolated_cb(unsigned long start_pfn,unsigned long nr_pages,void * data)1466 check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
1467 			void *data)
1468 {
1469 	int ret;
1470 	long offlined = *(long *)data;
1471 	ret = test_pages_isolated(start_pfn, start_pfn + nr_pages, true);
1472 	offlined = nr_pages;
1473 	if (!ret)
1474 		*(long *)data += offlined;
1475 	return ret;
1476 }
1477 
1478 static long
check_pages_isolated(unsigned long start_pfn,unsigned long end_pfn)1479 check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
1480 {
1481 	long offlined = 0;
1482 	int ret;
1483 
1484 	ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, &offlined,
1485 			check_pages_isolated_cb);
1486 	if (ret < 0)
1487 		offlined = (long)ret;
1488 	return offlined;
1489 }
1490 
cmdline_parse_movable_node(char * p)1491 static int __init cmdline_parse_movable_node(char *p)
1492 {
1493 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
1494 	movable_node_enabled = true;
1495 #else
1496 	pr_warn("movable_node parameter depends on CONFIG_HAVE_MEMBLOCK_NODE_MAP to work properly\n");
1497 #endif
1498 	return 0;
1499 }
1500 early_param("movable_node", cmdline_parse_movable_node);
1501 
1502 /* check which state of node_states will be changed when offline memory */
node_states_check_changes_offline(unsigned long nr_pages,struct zone * zone,struct memory_notify * arg)1503 static void node_states_check_changes_offline(unsigned long nr_pages,
1504 		struct zone *zone, struct memory_notify *arg)
1505 {
1506 	struct pglist_data *pgdat = zone->zone_pgdat;
1507 	unsigned long present_pages = 0;
1508 	enum zone_type zt, zone_last = ZONE_NORMAL;
1509 
1510 	/*
1511 	 * If we have HIGHMEM or movable node, node_states[N_NORMAL_MEMORY]
1512 	 * contains nodes which have zones of 0...ZONE_NORMAL,
1513 	 * set zone_last to ZONE_NORMAL.
1514 	 *
1515 	 * If we don't have HIGHMEM nor movable node,
1516 	 * node_states[N_NORMAL_MEMORY] contains nodes which have zones of
1517 	 * 0...ZONE_MOVABLE, set zone_last to ZONE_MOVABLE.
1518 	 */
1519 	if (N_MEMORY == N_NORMAL_MEMORY)
1520 		zone_last = ZONE_MOVABLE;
1521 
1522 	/*
1523 	 * check whether node_states[N_NORMAL_MEMORY] will be changed.
1524 	 * If the memory to be offline is in a zone of 0...zone_last,
1525 	 * and it is the last present memory, 0...zone_last will
1526 	 * become empty after offline , thus we can determind we will
1527 	 * need to clear the node from node_states[N_NORMAL_MEMORY].
1528 	 */
1529 	for (zt = 0; zt <= zone_last; zt++)
1530 		present_pages += pgdat->node_zones[zt].present_pages;
1531 	if (zone_idx(zone) <= zone_last && nr_pages >= present_pages)
1532 		arg->status_change_nid_normal = zone_to_nid(zone);
1533 	else
1534 		arg->status_change_nid_normal = -1;
1535 
1536 #ifdef CONFIG_HIGHMEM
1537 	/*
1538 	 * If we have movable node, node_states[N_HIGH_MEMORY]
1539 	 * contains nodes which have zones of 0...ZONE_HIGHMEM,
1540 	 * set zone_last to ZONE_HIGHMEM.
1541 	 *
1542 	 * If we don't have movable node, node_states[N_NORMAL_MEMORY]
1543 	 * contains nodes which have zones of 0...ZONE_MOVABLE,
1544 	 * set zone_last to ZONE_MOVABLE.
1545 	 */
1546 	zone_last = ZONE_HIGHMEM;
1547 	if (N_MEMORY == N_HIGH_MEMORY)
1548 		zone_last = ZONE_MOVABLE;
1549 
1550 	for (; zt <= zone_last; zt++)
1551 		present_pages += pgdat->node_zones[zt].present_pages;
1552 	if (zone_idx(zone) <= zone_last && nr_pages >= present_pages)
1553 		arg->status_change_nid_high = zone_to_nid(zone);
1554 	else
1555 		arg->status_change_nid_high = -1;
1556 #else
1557 	arg->status_change_nid_high = arg->status_change_nid_normal;
1558 #endif
1559 
1560 	/*
1561 	 * node_states[N_HIGH_MEMORY] contains nodes which have 0...ZONE_MOVABLE
1562 	 */
1563 	zone_last = ZONE_MOVABLE;
1564 
1565 	/*
1566 	 * check whether node_states[N_HIGH_MEMORY] will be changed
1567 	 * If we try to offline the last present @nr_pages from the node,
1568 	 * we can determind we will need to clear the node from
1569 	 * node_states[N_HIGH_MEMORY].
1570 	 */
1571 	for (; zt <= zone_last; zt++)
1572 		present_pages += pgdat->node_zones[zt].present_pages;
1573 	if (nr_pages >= present_pages)
1574 		arg->status_change_nid = zone_to_nid(zone);
1575 	else
1576 		arg->status_change_nid = -1;
1577 }
1578 
node_states_clear_node(int node,struct memory_notify * arg)1579 static void node_states_clear_node(int node, struct memory_notify *arg)
1580 {
1581 	if (arg->status_change_nid_normal >= 0)
1582 		node_clear_state(node, N_NORMAL_MEMORY);
1583 
1584 	if ((N_MEMORY != N_NORMAL_MEMORY) &&
1585 	    (arg->status_change_nid_high >= 0))
1586 		node_clear_state(node, N_HIGH_MEMORY);
1587 
1588 	if ((N_MEMORY != N_HIGH_MEMORY) &&
1589 	    (arg->status_change_nid >= 0))
1590 		node_clear_state(node, N_MEMORY);
1591 }
1592 
__offline_pages(unsigned long start_pfn,unsigned long end_pfn)1593 static int __ref __offline_pages(unsigned long start_pfn,
1594 		  unsigned long end_pfn)
1595 {
1596 	unsigned long pfn, nr_pages;
1597 	long offlined_pages;
1598 	int ret, node;
1599 	unsigned long flags;
1600 	unsigned long valid_start, valid_end;
1601 	struct zone *zone;
1602 	struct memory_notify arg;
1603 
1604 	/* at least, alignment against pageblock is necessary */
1605 	if (!IS_ALIGNED(start_pfn, pageblock_nr_pages))
1606 		return -EINVAL;
1607 	if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
1608 		return -EINVAL;
1609 	/* This makes hotplug much easier...and readable.
1610 	   we assume this for now. .*/
1611 	if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start, &valid_end))
1612 		return -EINVAL;
1613 
1614 	zone = page_zone(pfn_to_page(valid_start));
1615 	node = zone_to_nid(zone);
1616 	nr_pages = end_pfn - start_pfn;
1617 
1618 	/* set above range as isolated */
1619 	ret = start_isolate_page_range(start_pfn, end_pfn,
1620 				       MIGRATE_MOVABLE, true);
1621 	if (ret)
1622 		return ret;
1623 
1624 	arg.start_pfn = start_pfn;
1625 	arg.nr_pages = nr_pages;
1626 	node_states_check_changes_offline(nr_pages, zone, &arg);
1627 
1628 	ret = memory_notify(MEM_GOING_OFFLINE, &arg);
1629 	ret = notifier_to_errno(ret);
1630 	if (ret)
1631 		goto failed_removal;
1632 
1633 	pfn = start_pfn;
1634 repeat:
1635 	/* start memory hot removal */
1636 	ret = -EINTR;
1637 	if (signal_pending(current))
1638 		goto failed_removal;
1639 
1640 	cond_resched();
1641 	lru_add_drain_all();
1642 	drain_all_pages(zone);
1643 
1644 	pfn = scan_movable_pages(start_pfn, end_pfn);
1645 	if (pfn) { /* We have movable pages */
1646 		ret = do_migrate_range(pfn, end_pfn);
1647 		goto repeat;
1648 	}
1649 
1650 	/*
1651 	 * dissolve free hugepages in the memory block before doing offlining
1652 	 * actually in order to make hugetlbfs's object counting consistent.
1653 	 */
1654 	ret = dissolve_free_huge_pages(start_pfn, end_pfn);
1655 	if (ret)
1656 		goto failed_removal;
1657 	/* check again */
1658 	offlined_pages = check_pages_isolated(start_pfn, end_pfn);
1659 	if (offlined_pages < 0)
1660 		goto repeat;
1661 	pr_info("Offlined Pages %ld\n", offlined_pages);
1662 	/* Ok, all of our target is isolated.
1663 	   We cannot do rollback at this point. */
1664 	offline_isolated_pages(start_pfn, end_pfn);
1665 	/* reset pagetype flags and makes migrate type to be MOVABLE */
1666 	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
1667 	/* removal success */
1668 	adjust_managed_page_count(pfn_to_page(start_pfn), -offlined_pages);
1669 	zone->present_pages -= offlined_pages;
1670 
1671 	pgdat_resize_lock(zone->zone_pgdat, &flags);
1672 	zone->zone_pgdat->node_present_pages -= offlined_pages;
1673 	pgdat_resize_unlock(zone->zone_pgdat, &flags);
1674 
1675 	init_per_zone_wmark_min();
1676 
1677 	if (!populated_zone(zone)) {
1678 		zone_pcp_reset(zone);
1679 		build_all_zonelists(NULL);
1680 	} else
1681 		zone_pcp_update(zone);
1682 
1683 	node_states_clear_node(node, &arg);
1684 	if (arg.status_change_nid >= 0) {
1685 		kswapd_stop(node);
1686 		kcompactd_stop(node);
1687 	}
1688 
1689 	vm_total_pages = nr_free_pagecache_pages();
1690 	writeback_set_ratelimit();
1691 
1692 	memory_notify(MEM_OFFLINE, &arg);
1693 	return 0;
1694 
1695 failed_removal:
1696 	pr_debug("memory offlining [mem %#010llx-%#010llx] failed\n",
1697 		 (unsigned long long) start_pfn << PAGE_SHIFT,
1698 		 ((unsigned long long) end_pfn << PAGE_SHIFT) - 1);
1699 	memory_notify(MEM_CANCEL_OFFLINE, &arg);
1700 	/* pushback to free area */
1701 	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
1702 	return ret;
1703 }
1704 
1705 /* Must be protected by mem_hotplug_begin() or a device_lock */
offline_pages(unsigned long start_pfn,unsigned long nr_pages)1706 int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
1707 {
1708 	return __offline_pages(start_pfn, start_pfn + nr_pages);
1709 }
1710 #endif /* CONFIG_MEMORY_HOTREMOVE */
1711 
1712 /**
1713  * walk_memory_range - walks through all mem sections in [start_pfn, end_pfn)
1714  * @start_pfn: start pfn of the memory range
1715  * @end_pfn: end pfn of the memory range
1716  * @arg: argument passed to func
1717  * @func: callback for each memory section walked
1718  *
1719  * This function walks through all present mem sections in range
1720  * [start_pfn, end_pfn) and call func on each mem section.
1721  *
1722  * Returns the return value of func.
1723  */
walk_memory_range(unsigned long start_pfn,unsigned long end_pfn,void * arg,int (* func)(struct memory_block *,void *))1724 int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
1725 		void *arg, int (*func)(struct memory_block *, void *))
1726 {
1727 	struct memory_block *mem = NULL;
1728 	struct mem_section *section;
1729 	unsigned long pfn, section_nr;
1730 	int ret;
1731 
1732 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
1733 		section_nr = pfn_to_section_nr(pfn);
1734 		if (!present_section_nr(section_nr))
1735 			continue;
1736 
1737 		section = __nr_to_section(section_nr);
1738 		/* same memblock? */
1739 		if (mem)
1740 			if ((section_nr >= mem->start_section_nr) &&
1741 			    (section_nr <= mem->end_section_nr))
1742 				continue;
1743 
1744 		mem = find_memory_block_hinted(section, mem);
1745 		if (!mem)
1746 			continue;
1747 
1748 		ret = func(mem, arg);
1749 		if (ret) {
1750 			kobject_put(&mem->dev.kobj);
1751 			return ret;
1752 		}
1753 	}
1754 
1755 	if (mem)
1756 		kobject_put(&mem->dev.kobj);
1757 
1758 	return 0;
1759 }
1760 
1761 #ifdef CONFIG_MEMORY_HOTREMOVE
check_memblock_offlined_cb(struct memory_block * mem,void * arg)1762 static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)
1763 {
1764 	int ret = !is_memblock_offlined(mem);
1765 
1766 	if (unlikely(ret)) {
1767 		phys_addr_t beginpa, endpa;
1768 
1769 		beginpa = PFN_PHYS(section_nr_to_pfn(mem->start_section_nr));
1770 		endpa = PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1))-1;
1771 		pr_warn("removing memory fails, because memory [%pa-%pa] is onlined\n",
1772 			&beginpa, &endpa);
1773 	}
1774 
1775 	return ret;
1776 }
1777 
check_cpu_on_node(pg_data_t * pgdat)1778 static int check_cpu_on_node(pg_data_t *pgdat)
1779 {
1780 	int cpu;
1781 
1782 	for_each_present_cpu(cpu) {
1783 		if (cpu_to_node(cpu) == pgdat->node_id)
1784 			/*
1785 			 * the cpu on this node isn't removed, and we can't
1786 			 * offline this node.
1787 			 */
1788 			return -EBUSY;
1789 	}
1790 
1791 	return 0;
1792 }
1793 
unmap_cpu_on_node(pg_data_t * pgdat)1794 static void unmap_cpu_on_node(pg_data_t *pgdat)
1795 {
1796 #ifdef CONFIG_ACPI_NUMA
1797 	int cpu;
1798 
1799 	for_each_possible_cpu(cpu)
1800 		if (cpu_to_node(cpu) == pgdat->node_id)
1801 			numa_clear_node(cpu);
1802 #endif
1803 }
1804 
check_and_unmap_cpu_on_node(pg_data_t * pgdat)1805 static int check_and_unmap_cpu_on_node(pg_data_t *pgdat)
1806 {
1807 	int ret;
1808 
1809 	ret = check_cpu_on_node(pgdat);
1810 	if (ret)
1811 		return ret;
1812 
1813 	/*
1814 	 * the node will be offlined when we come here, so we can clear
1815 	 * the cpu_to_node() now.
1816 	 */
1817 
1818 	unmap_cpu_on_node(pgdat);
1819 	return 0;
1820 }
1821 
1822 /**
1823  * try_offline_node
1824  * @nid: the node ID
1825  *
1826  * Offline a node if all memory sections and cpus of the node are removed.
1827  *
1828  * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
1829  * and online/offline operations before this call.
1830  */
try_offline_node(int nid)1831 void try_offline_node(int nid)
1832 {
1833 	pg_data_t *pgdat = NODE_DATA(nid);
1834 	unsigned long start_pfn = pgdat->node_start_pfn;
1835 	unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
1836 	unsigned long pfn;
1837 
1838 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
1839 		unsigned long section_nr = pfn_to_section_nr(pfn);
1840 
1841 		if (!present_section_nr(section_nr))
1842 			continue;
1843 
1844 		if (pfn_to_nid(pfn) != nid)
1845 			continue;
1846 
1847 		/*
1848 		 * some memory sections of this node are not removed, and we
1849 		 * can't offline node now.
1850 		 */
1851 		return;
1852 	}
1853 
1854 	if (check_and_unmap_cpu_on_node(pgdat))
1855 		return;
1856 
1857 	/*
1858 	 * all memory/cpu of this node are removed, we can offline this
1859 	 * node now.
1860 	 */
1861 	node_set_offline(nid);
1862 	unregister_one_node(nid);
1863 }
1864 EXPORT_SYMBOL(try_offline_node);
1865 
1866 /**
1867  * remove_memory
1868  * @nid: the node ID
1869  * @start: physical address of the region to remove
1870  * @size: size of the region to remove
1871  *
1872  * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
1873  * and online/offline operations before this call, as required by
1874  * try_offline_node().
1875  */
remove_memory(int nid,u64 start,u64 size)1876 void __ref remove_memory(int nid, u64 start, u64 size)
1877 {
1878 	int ret;
1879 
1880 	BUG_ON(check_hotplug_memory_range(start, size));
1881 
1882 	mem_hotplug_begin();
1883 
1884 	/*
1885 	 * All memory blocks must be offlined before removing memory.  Check
1886 	 * whether all memory blocks in question are offline and trigger a BUG()
1887 	 * if this is not the case.
1888 	 */
1889 	ret = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL,
1890 				check_memblock_offlined_cb);
1891 	if (ret)
1892 		BUG();
1893 
1894 	/* remove memmap entry */
1895 	firmware_map_remove(start, start + size, "System RAM");
1896 	memblock_free(start, size);
1897 	memblock_remove(start, size);
1898 
1899 	arch_remove_memory(start, size, NULL);
1900 
1901 	try_offline_node(nid);
1902 
1903 	mem_hotplug_done();
1904 }
1905 EXPORT_SYMBOL_GPL(remove_memory);
1906 #endif /* CONFIG_MEMORY_HOTREMOVE */
1907