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Linux/mm/memory_hotplug.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  *  linux/mm/memory_hotplug.c
  4  *
  5  *  Copyright (C)
  6  */
  7 
  8 #include <linux/stddef.h>
  9 #include <linux/mm.h>
 10 #include <linux/sched/signal.h>
 11 #include <linux/swap.h>
 12 #include <linux/interrupt.h>
 13 #include <linux/pagemap.h>
 14 #include <linux/compiler.h>
 15 #include <linux/export.h>
 16 #include <linux/pagevec.h>
 17 #include <linux/writeback.h>
 18 #include <linux/slab.h>
 19 #include <linux/sysctl.h>
 20 #include <linux/cpu.h>
 21 #include <linux/memory.h>
 22 #include <linux/memremap.h>
 23 #include <linux/memory_hotplug.h>
 24 #include <linux/highmem.h>
 25 #include <linux/vmalloc.h>
 26 #include <linux/ioport.h>
 27 #include <linux/delay.h>
 28 #include <linux/migrate.h>
 29 #include <linux/page-isolation.h>
 30 #include <linux/pfn.h>
 31 #include <linux/suspend.h>
 32 #include <linux/mm_inline.h>
 33 #include <linux/firmware-map.h>
 34 #include <linux/stop_machine.h>
 35 #include <linux/hugetlb.h>
 36 #include <linux/memblock.h>
 37 #include <linux/compaction.h>
 38 #include <linux/rmap.h>
 39 
 40 #include <asm/tlbflush.h>
 41 
 42 #include "internal.h"
 43 #include "shuffle.h"
 44 
 45 
 46 /*
 47  * memory_hotplug.memmap_on_memory parameter
 48  */
 49 static bool memmap_on_memory __ro_after_init;
 50 #ifdef CONFIG_MHP_MEMMAP_ON_MEMORY
 51 module_param(memmap_on_memory, bool, 0444);
 52 MODULE_PARM_DESC(memmap_on_memory, "Enable memmap on memory for memory hotplug");
 53 #endif
 54 
 55 /*
 56  * online_page_callback contains pointer to current page onlining function.
 57  * Initially it is generic_online_page(). If it is required it could be
 58  * changed by calling set_online_page_callback() for callback registration
 59  * and restore_online_page_callback() for generic callback restore.
 60  */
 61 
 62 static online_page_callback_t online_page_callback = generic_online_page;
 63 static DEFINE_MUTEX(online_page_callback_lock);
 64 
 65 DEFINE_STATIC_PERCPU_RWSEM(mem_hotplug_lock);
 66 
 67 void get_online_mems(void)
 68 {
 69         percpu_down_read(&mem_hotplug_lock);
 70 }
 71 
 72 void put_online_mems(void)
 73 {
 74         percpu_up_read(&mem_hotplug_lock);
 75 }
 76 
 77 bool movable_node_enabled = false;
 78 
 79 #ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
 80 int mhp_default_online_type = MMOP_OFFLINE;
 81 #else
 82 int mhp_default_online_type = MMOP_ONLINE;
 83 #endif
 84 
 85 static int __init setup_memhp_default_state(char *str)
 86 {
 87         const int online_type = mhp_online_type_from_str(str);
 88 
 89         if (online_type >= 0)
 90                 mhp_default_online_type = online_type;
 91 
 92         return 1;
 93 }
 94 __setup("memhp_default_state=", setup_memhp_default_state);
 95 
 96 void mem_hotplug_begin(void)
 97 {
 98         cpus_read_lock();
 99         percpu_down_write(&mem_hotplug_lock);
100 }
101 
102 void mem_hotplug_done(void)
103 {
104         percpu_up_write(&mem_hotplug_lock);
105         cpus_read_unlock();
106 }
107 
108 u64 max_mem_size = U64_MAX;
109 
110 /* add this memory to iomem resource */
111 static struct resource *register_memory_resource(u64 start, u64 size,
112                                                  const char *resource_name)
113 {
114         struct resource *res;
115         unsigned long flags =  IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
116 
117         if (strcmp(resource_name, "System RAM"))
118                 flags |= IORESOURCE_SYSRAM_DRIVER_MANAGED;
119 
120         if (!mhp_range_allowed(start, size, true))
121                 return ERR_PTR(-E2BIG);
122 
123         /*
124          * Make sure value parsed from 'mem=' only restricts memory adding
125          * while booting, so that memory hotplug won't be impacted. Please
126          * refer to document of 'mem=' in kernel-parameters.txt for more
127          * details.
128          */
129         if (start + size > max_mem_size && system_state < SYSTEM_RUNNING)
130                 return ERR_PTR(-E2BIG);
131 
132         /*
133          * Request ownership of the new memory range.  This might be
134          * a child of an existing resource that was present but
135          * not marked as busy.
136          */
137         res = __request_region(&iomem_resource, start, size,
138                                resource_name, flags);
139 
140         if (!res) {
141                 pr_debug("Unable to reserve System RAM region: %016llx->%016llx\n",
142                                 start, start + size);
143                 return ERR_PTR(-EEXIST);
144         }
145         return res;
146 }
147 
148 static void release_memory_resource(struct resource *res)
149 {
150         if (!res)
151                 return;
152         release_resource(res);
153         kfree(res);
154 }
155 
156 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
157 void get_page_bootmem(unsigned long info,  struct page *page,
158                       unsigned long type)
159 {
160         page->freelist = (void *)type;
161         SetPagePrivate(page);
162         set_page_private(page, info);
163         page_ref_inc(page);
164 }
165 
166 void put_page_bootmem(struct page *page)
167 {
168         unsigned long type;
169 
170         type = (unsigned long) page->freelist;
171         BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
172                type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE);
173 
174         if (page_ref_dec_return(page) == 1) {
175                 page->freelist = NULL;
176                 ClearPagePrivate(page);
177                 set_page_private(page, 0);
178                 INIT_LIST_HEAD(&page->lru);
179                 free_reserved_page(page);
180         }
181 }
182 
183 #ifdef CONFIG_HAVE_BOOTMEM_INFO_NODE
184 #ifndef CONFIG_SPARSEMEM_VMEMMAP
185 static void register_page_bootmem_info_section(unsigned long start_pfn)
186 {
187         unsigned long mapsize, section_nr, i;
188         struct mem_section *ms;
189         struct page *page, *memmap;
190         struct mem_section_usage *usage;
191 
192         section_nr = pfn_to_section_nr(start_pfn);
193         ms = __nr_to_section(section_nr);
194 
195         /* Get section's memmap address */
196         memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
197 
198         /*
199          * Get page for the memmap's phys address
200          * XXX: need more consideration for sparse_vmemmap...
201          */
202         page = virt_to_page(memmap);
203         mapsize = sizeof(struct page) * PAGES_PER_SECTION;
204         mapsize = PAGE_ALIGN(mapsize) >> PAGE_SHIFT;
205 
206         /* remember memmap's page */
207         for (i = 0; i < mapsize; i++, page++)
208                 get_page_bootmem(section_nr, page, SECTION_INFO);
209 
210         usage = ms->usage;
211         page = virt_to_page(usage);
212 
213         mapsize = PAGE_ALIGN(mem_section_usage_size()) >> PAGE_SHIFT;
214 
215         for (i = 0; i < mapsize; i++, page++)
216                 get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
217 
218 }
219 #else /* CONFIG_SPARSEMEM_VMEMMAP */
220 static void register_page_bootmem_info_section(unsigned long start_pfn)
221 {
222         unsigned long mapsize, section_nr, i;
223         struct mem_section *ms;
224         struct page *page, *memmap;
225         struct mem_section_usage *usage;
226 
227         section_nr = pfn_to_section_nr(start_pfn);
228         ms = __nr_to_section(section_nr);
229 
230         memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
231 
232         register_page_bootmem_memmap(section_nr, memmap, PAGES_PER_SECTION);
233 
234         usage = ms->usage;
235         page = virt_to_page(usage);
236 
237         mapsize = PAGE_ALIGN(mem_section_usage_size()) >> PAGE_SHIFT;
238 
239         for (i = 0; i < mapsize; i++, page++)
240                 get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
241 }
242 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
243 
244 void __init register_page_bootmem_info_node(struct pglist_data *pgdat)
245 {
246         unsigned long i, pfn, end_pfn, nr_pages;
247         int node = pgdat->node_id;
248         struct page *page;
249 
250         nr_pages = PAGE_ALIGN(sizeof(struct pglist_data)) >> PAGE_SHIFT;
251         page = virt_to_page(pgdat);
252 
253         for (i = 0; i < nr_pages; i++, page++)
254                 get_page_bootmem(node, page, NODE_INFO);
255 
256         pfn = pgdat->node_start_pfn;
257         end_pfn = pgdat_end_pfn(pgdat);
258 
259         /* register section info */
260         for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
261                 /*
262                  * Some platforms can assign the same pfn to multiple nodes - on
263                  * node0 as well as nodeN.  To avoid registering a pfn against
264                  * multiple nodes we check that this pfn does not already
265                  * reside in some other nodes.
266                  */
267                 if (pfn_valid(pfn) && (early_pfn_to_nid(pfn) == node))
268                         register_page_bootmem_info_section(pfn);
269         }
270 }
271 #endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */
272 
273 static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
274                 const char *reason)
275 {
276         /*
277          * Disallow all operations smaller than a sub-section and only
278          * allow operations smaller than a section for
279          * SPARSEMEM_VMEMMAP. Note that check_hotplug_memory_range()
280          * enforces a larger memory_block_size_bytes() granularity for
281          * memory that will be marked online, so this check should only
282          * fire for direct arch_{add,remove}_memory() users outside of
283          * add_memory_resource().
284          */
285         unsigned long min_align;
286 
287         if (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP))
288                 min_align = PAGES_PER_SUBSECTION;
289         else
290                 min_align = PAGES_PER_SECTION;
291         if (!IS_ALIGNED(pfn, min_align)
292                         || !IS_ALIGNED(nr_pages, min_align)) {
293                 WARN(1, "Misaligned __%s_pages start: %#lx end: #%lx\n",
294                                 reason, pfn, pfn + nr_pages - 1);
295                 return -EINVAL;
296         }
297         return 0;
298 }
299 
300 /*
301  * Return page for the valid pfn only if the page is online. All pfn
302  * walkers which rely on the fully initialized page->flags and others
303  * should use this rather than pfn_valid && pfn_to_page
304  */
305 struct page *pfn_to_online_page(unsigned long pfn)
306 {
307         unsigned long nr = pfn_to_section_nr(pfn);
308         struct dev_pagemap *pgmap;
309         struct mem_section *ms;
310 
311         if (nr >= NR_MEM_SECTIONS)
312                 return NULL;
313 
314         ms = __nr_to_section(nr);
315         if (!online_section(ms))
316                 return NULL;
317 
318         /*
319          * Save some code text when online_section() +
320          * pfn_section_valid() are sufficient.
321          */
322         if (IS_ENABLED(CONFIG_HAVE_ARCH_PFN_VALID) && !pfn_valid(pfn))
323                 return NULL;
324 
325         if (!pfn_section_valid(ms, pfn))
326                 return NULL;
327 
328         if (!online_device_section(ms))
329                 return pfn_to_page(pfn);
330 
331         /*
332          * Slowpath: when ZONE_DEVICE collides with
333          * ZONE_{NORMAL,MOVABLE} within the same section some pfns in
334          * the section may be 'offline' but 'valid'. Only
335          * get_dev_pagemap() can determine sub-section online status.
336          */
337         pgmap = get_dev_pagemap(pfn, NULL);
338         put_dev_pagemap(pgmap);
339 
340         /* The presence of a pgmap indicates ZONE_DEVICE offline pfn */
341         if (pgmap)
342                 return NULL;
343 
344         return pfn_to_page(pfn);
345 }
346 EXPORT_SYMBOL_GPL(pfn_to_online_page);
347 
348 /*
349  * Reasonably generic function for adding memory.  It is
350  * expected that archs that support memory hotplug will
351  * call this function after deciding the zone to which to
352  * add the new pages.
353  */
354 int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
355                 struct mhp_params *params)
356 {
357         const unsigned long end_pfn = pfn + nr_pages;
358         unsigned long cur_nr_pages;
359         int err;
360         struct vmem_altmap *altmap = params->altmap;
361 
362         if (WARN_ON_ONCE(!params->pgprot.pgprot))
363                 return -EINVAL;
364 
365         VM_BUG_ON(!mhp_range_allowed(PFN_PHYS(pfn), nr_pages * PAGE_SIZE, false));
366 
367         if (altmap) {
368                 /*
369                  * Validate altmap is within bounds of the total request
370                  */
371                 if (altmap->base_pfn != pfn
372                                 || vmem_altmap_offset(altmap) > nr_pages) {
373                         pr_warn_once("memory add fail, invalid altmap\n");
374                         return -EINVAL;
375                 }
376                 altmap->alloc = 0;
377         }
378 
379         err = check_pfn_span(pfn, nr_pages, "add");
380         if (err)
381                 return err;
382 
383         for (; pfn < end_pfn; pfn += cur_nr_pages) {
384                 /* Select all remaining pages up to the next section boundary */
385                 cur_nr_pages = min(end_pfn - pfn,
386                                    SECTION_ALIGN_UP(pfn + 1) - pfn);
387                 err = sparse_add_section(nid, pfn, cur_nr_pages, altmap);
388                 if (err)
389                         break;
390                 cond_resched();
391         }
392         vmemmap_populate_print_last();
393         return err;
394 }
395 
396 /* find the smallest valid pfn in the range [start_pfn, end_pfn) */
397 static unsigned long find_smallest_section_pfn(int nid, struct zone *zone,
398                                      unsigned long start_pfn,
399                                      unsigned long end_pfn)
400 {
401         for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SUBSECTION) {
402                 if (unlikely(!pfn_to_online_page(start_pfn)))
403                         continue;
404 
405                 if (unlikely(pfn_to_nid(start_pfn) != nid))
406                         continue;
407 
408                 if (zone != page_zone(pfn_to_page(start_pfn)))
409                         continue;
410 
411                 return start_pfn;
412         }
413 
414         return 0;
415 }
416 
417 /* find the biggest valid pfn in the range [start_pfn, end_pfn). */
418 static unsigned long find_biggest_section_pfn(int nid, struct zone *zone,
419                                     unsigned long start_pfn,
420                                     unsigned long end_pfn)
421 {
422         unsigned long pfn;
423 
424         /* pfn is the end pfn of a memory section. */
425         pfn = end_pfn - 1;
426         for (; pfn >= start_pfn; pfn -= PAGES_PER_SUBSECTION) {
427                 if (unlikely(!pfn_to_online_page(pfn)))
428                         continue;
429 
430                 if (unlikely(pfn_to_nid(pfn) != nid))
431                         continue;
432 
433                 if (zone != page_zone(pfn_to_page(pfn)))
434                         continue;
435 
436                 return pfn;
437         }
438 
439         return 0;
440 }
441 
442 static void shrink_zone_span(struct zone *zone, unsigned long start_pfn,
443                              unsigned long end_pfn)
444 {
445         unsigned long pfn;
446         int nid = zone_to_nid(zone);
447 
448         zone_span_writelock(zone);
449         if (zone->zone_start_pfn == start_pfn) {
450                 /*
451                  * If the section is smallest section in the zone, it need
452                  * shrink zone->zone_start_pfn and zone->zone_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, zone, end_pfn,
457                                                 zone_end_pfn(zone));
458                 if (pfn) {
459                         zone->spanned_pages = zone_end_pfn(zone) - pfn;
460                         zone->zone_start_pfn = pfn;
461                 } else {
462                         zone->zone_start_pfn = 0;
463                         zone->spanned_pages = 0;
464                 }
465         } else if (zone_end_pfn(zone) == end_pfn) {
466                 /*
467                  * If the section is biggest section in the zone, it need
468                  * shrink zone->spanned_pages.
469                  * In this case, we find second biggest valid mem_section for
470                  * shrinking zone.
471                  */
472                 pfn = find_biggest_section_pfn(nid, zone, zone->zone_start_pfn,
473                                                start_pfn);
474                 if (pfn)
475                         zone->spanned_pages = pfn - zone->zone_start_pfn + 1;
476                 else {
477                         zone->zone_start_pfn = 0;
478                         zone->spanned_pages = 0;
479                 }
480         }
481         zone_span_writeunlock(zone);
482 }
483 
484 static void update_pgdat_span(struct pglist_data *pgdat)
485 {
486         unsigned long node_start_pfn = 0, node_end_pfn = 0;
487         struct zone *zone;
488 
489         for (zone = pgdat->node_zones;
490              zone < pgdat->node_zones + MAX_NR_ZONES; zone++) {
491                 unsigned long end_pfn = zone_end_pfn(zone);
492 
493                 /* No need to lock the zones, they can't change. */
494                 if (!zone->spanned_pages)
495                         continue;
496                 if (!node_end_pfn) {
497                         node_start_pfn = zone->zone_start_pfn;
498                         node_end_pfn = end_pfn;
499                         continue;
500                 }
501 
502                 if (end_pfn > node_end_pfn)
503                         node_end_pfn = end_pfn;
504                 if (zone->zone_start_pfn < node_start_pfn)
505                         node_start_pfn = zone->zone_start_pfn;
506         }
507 
508         pgdat->node_start_pfn = node_start_pfn;
509         pgdat->node_spanned_pages = node_end_pfn - node_start_pfn;
510 }
511 
512 void __ref remove_pfn_range_from_zone(struct zone *zone,
513                                       unsigned long start_pfn,
514                                       unsigned long nr_pages)
515 {
516         const unsigned long end_pfn = start_pfn + nr_pages;
517         struct pglist_data *pgdat = zone->zone_pgdat;
518         unsigned long pfn, cur_nr_pages, flags;
519 
520         /* Poison struct pages because they are now uninitialized again. */
521         for (pfn = start_pfn; pfn < end_pfn; pfn += cur_nr_pages) {
522                 cond_resched();
523 
524                 /* Select all remaining pages up to the next section boundary */
525                 cur_nr_pages =
526                         min(end_pfn - pfn, SECTION_ALIGN_UP(pfn + 1) - pfn);
527                 page_init_poison(pfn_to_page(pfn),
528                                  sizeof(struct page) * cur_nr_pages);
529         }
530 
531 #ifdef CONFIG_ZONE_DEVICE
532         /*
533          * Zone shrinking code cannot properly deal with ZONE_DEVICE. So
534          * we will not try to shrink the zones - which is okay as
535          * set_zone_contiguous() cannot deal with ZONE_DEVICE either way.
536          */
537         if (zone_idx(zone) == ZONE_DEVICE)
538                 return;
539 #endif
540 
541         clear_zone_contiguous(zone);
542 
543         pgdat_resize_lock(zone->zone_pgdat, &flags);
544         shrink_zone_span(zone, start_pfn, start_pfn + nr_pages);
545         update_pgdat_span(pgdat);
546         pgdat_resize_unlock(zone->zone_pgdat, &flags);
547 
548         set_zone_contiguous(zone);
549 }
550 
551 static void __remove_section(unsigned long pfn, unsigned long nr_pages,
552                              unsigned long map_offset,
553                              struct vmem_altmap *altmap)
554 {
555         struct mem_section *ms = __pfn_to_section(pfn);
556 
557         if (WARN_ON_ONCE(!valid_section(ms)))
558                 return;
559 
560         sparse_remove_section(ms, pfn, nr_pages, map_offset, altmap);
561 }
562 
563 /**
564  * __remove_pages() - remove sections of pages
565  * @pfn: starting pageframe (must be aligned to start of a section)
566  * @nr_pages: number of pages to remove (must be multiple of section size)
567  * @altmap: alternative device page map or %NULL if default memmap is used
568  *
569  * Generic helper function to remove section mappings and sysfs entries
570  * for the section of the memory we are removing. Caller needs to make
571  * sure that pages are marked reserved and zones are adjust properly by
572  * calling offline_pages().
573  */
574 void __remove_pages(unsigned long pfn, unsigned long nr_pages,
575                     struct vmem_altmap *altmap)
576 {
577         const unsigned long end_pfn = pfn + nr_pages;
578         unsigned long cur_nr_pages;
579         unsigned long map_offset = 0;
580 
581         map_offset = vmem_altmap_offset(altmap);
582 
583         if (check_pfn_span(pfn, nr_pages, "remove"))
584                 return;
585 
586         for (; pfn < end_pfn; pfn += cur_nr_pages) {
587                 cond_resched();
588                 /* Select all remaining pages up to the next section boundary */
589                 cur_nr_pages = min(end_pfn - pfn,
590                                    SECTION_ALIGN_UP(pfn + 1) - pfn);
591                 __remove_section(pfn, cur_nr_pages, map_offset, altmap);
592                 map_offset = 0;
593         }
594 }
595 
596 int set_online_page_callback(online_page_callback_t callback)
597 {
598         int rc = -EINVAL;
599 
600         get_online_mems();
601         mutex_lock(&online_page_callback_lock);
602 
603         if (online_page_callback == generic_online_page) {
604                 online_page_callback = callback;
605                 rc = 0;
606         }
607 
608         mutex_unlock(&online_page_callback_lock);
609         put_online_mems();
610 
611         return rc;
612 }
613 EXPORT_SYMBOL_GPL(set_online_page_callback);
614 
615 int restore_online_page_callback(online_page_callback_t callback)
616 {
617         int rc = -EINVAL;
618 
619         get_online_mems();
620         mutex_lock(&online_page_callback_lock);
621 
622         if (online_page_callback == callback) {
623                 online_page_callback = generic_online_page;
624                 rc = 0;
625         }
626 
627         mutex_unlock(&online_page_callback_lock);
628         put_online_mems();
629 
630         return rc;
631 }
632 EXPORT_SYMBOL_GPL(restore_online_page_callback);
633 
634 void generic_online_page(struct page *page, unsigned int order)
635 {
636         /*
637          * Freeing the page with debug_pagealloc enabled will try to unmap it,
638          * so we should map it first. This is better than introducing a special
639          * case in page freeing fast path.
640          */
641         debug_pagealloc_map_pages(page, 1 << order);
642         __free_pages_core(page, order);
643         totalram_pages_add(1UL << order);
644 #ifdef CONFIG_HIGHMEM
645         if (PageHighMem(page))
646                 totalhigh_pages_add(1UL << order);
647 #endif
648 }
649 EXPORT_SYMBOL_GPL(generic_online_page);
650 
651 static void online_pages_range(unsigned long start_pfn, unsigned long nr_pages)
652 {
653         const unsigned long end_pfn = start_pfn + nr_pages;
654         unsigned long pfn;
655 
656         /*
657          * Online the pages in MAX_ORDER - 1 aligned chunks. The callback might
658          * decide to not expose all pages to the buddy (e.g., expose them
659          * later). We account all pages as being online and belonging to this
660          * zone ("present").
661          * When using memmap_on_memory, the range might not be aligned to
662          * MAX_ORDER_NR_PAGES - 1, but pageblock aligned. __ffs() will detect
663          * this and the first chunk to online will be pageblock_nr_pages.
664          */
665         for (pfn = start_pfn; pfn < end_pfn;) {
666                 int order = min(MAX_ORDER - 1UL, __ffs(pfn));
667 
668                 (*online_page_callback)(pfn_to_page(pfn), order);
669                 pfn += (1UL << order);
670         }
671 
672         /* mark all involved sections as online */
673         online_mem_sections(start_pfn, end_pfn);
674 }
675 
676 /* check which state of node_states will be changed when online memory */
677 static void node_states_check_changes_online(unsigned long nr_pages,
678         struct zone *zone, struct memory_notify *arg)
679 {
680         int nid = zone_to_nid(zone);
681 
682         arg->status_change_nid = NUMA_NO_NODE;
683         arg->status_change_nid_normal = NUMA_NO_NODE;
684         arg->status_change_nid_high = NUMA_NO_NODE;
685 
686         if (!node_state(nid, N_MEMORY))
687                 arg->status_change_nid = nid;
688         if (zone_idx(zone) <= ZONE_NORMAL && !node_state(nid, N_NORMAL_MEMORY))
689                 arg->status_change_nid_normal = nid;
690 #ifdef CONFIG_HIGHMEM
691         if (zone_idx(zone) <= ZONE_HIGHMEM && !node_state(nid, N_HIGH_MEMORY))
692                 arg->status_change_nid_high = nid;
693 #endif
694 }
695 
696 static void node_states_set_node(int node, struct memory_notify *arg)
697 {
698         if (arg->status_change_nid_normal >= 0)
699                 node_set_state(node, N_NORMAL_MEMORY);
700 
701         if (arg->status_change_nid_high >= 0)
702                 node_set_state(node, N_HIGH_MEMORY);
703 
704         if (arg->status_change_nid >= 0)
705                 node_set_state(node, N_MEMORY);
706 }
707 
708 static void __meminit resize_zone_range(struct zone *zone, unsigned long start_pfn,
709                 unsigned long nr_pages)
710 {
711         unsigned long old_end_pfn = zone_end_pfn(zone);
712 
713         if (zone_is_empty(zone) || start_pfn < zone->zone_start_pfn)
714                 zone->zone_start_pfn = start_pfn;
715 
716         zone->spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - zone->zone_start_pfn;
717 }
718 
719 static void __meminit resize_pgdat_range(struct pglist_data *pgdat, unsigned long start_pfn,
720                                      unsigned long nr_pages)
721 {
722         unsigned long old_end_pfn = pgdat_end_pfn(pgdat);
723 
724         if (!pgdat->node_spanned_pages || start_pfn < pgdat->node_start_pfn)
725                 pgdat->node_start_pfn = start_pfn;
726 
727         pgdat->node_spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - pgdat->node_start_pfn;
728 
729 }
730 
731 static void section_taint_zone_device(unsigned long pfn)
732 {
733         struct mem_section *ms = __pfn_to_section(pfn);
734 
735         ms->section_mem_map |= SECTION_TAINT_ZONE_DEVICE;
736 }
737 
738 /*
739  * Associate the pfn range with the given zone, initializing the memmaps
740  * and resizing the pgdat/zone data to span the added pages. After this
741  * call, all affected pages are PG_reserved.
742  *
743  * All aligned pageblocks are initialized to the specified migratetype
744  * (usually MIGRATE_MOVABLE). Besides setting the migratetype, no related
745  * zone stats (e.g., nr_isolate_pageblock) are touched.
746  */
747 void __ref move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
748                                   unsigned long nr_pages,
749                                   struct vmem_altmap *altmap, int migratetype)
750 {
751         struct pglist_data *pgdat = zone->zone_pgdat;
752         int nid = pgdat->node_id;
753         unsigned long flags;
754 
755         clear_zone_contiguous(zone);
756 
757         /* TODO Huh pgdat is irqsave while zone is not. It used to be like that before */
758         pgdat_resize_lock(pgdat, &flags);
759         zone_span_writelock(zone);
760         if (zone_is_empty(zone))
761                 init_currently_empty_zone(zone, start_pfn, nr_pages);
762         resize_zone_range(zone, start_pfn, nr_pages);
763         zone_span_writeunlock(zone);
764         resize_pgdat_range(pgdat, start_pfn, nr_pages);
765         pgdat_resize_unlock(pgdat, &flags);
766 
767         /*
768          * Subsection population requires care in pfn_to_online_page().
769          * Set the taint to enable the slow path detection of
770          * ZONE_DEVICE pages in an otherwise  ZONE_{NORMAL,MOVABLE}
771          * section.
772          */
773         if (zone_is_zone_device(zone)) {
774                 if (!IS_ALIGNED(start_pfn, PAGES_PER_SECTION))
775                         section_taint_zone_device(start_pfn);
776                 if (!IS_ALIGNED(start_pfn + nr_pages, PAGES_PER_SECTION))
777                         section_taint_zone_device(start_pfn + nr_pages);
778         }
779 
780         /*
781          * TODO now we have a visible range of pages which are not associated
782          * with their zone properly. Not nice but set_pfnblock_flags_mask
783          * expects the zone spans the pfn range. All the pages in the range
784          * are reserved so nobody should be touching them so we should be safe
785          */
786         memmap_init_range(nr_pages, nid, zone_idx(zone), start_pfn, 0,
787                          MEMINIT_HOTPLUG, altmap, migratetype);
788 
789         set_zone_contiguous(zone);
790 }
791 
792 /*
793  * Returns a default kernel memory zone for the given pfn range.
794  * If no kernel zone covers this pfn range it will automatically go
795  * to the ZONE_NORMAL.
796  */
797 static struct zone *default_kernel_zone_for_pfn(int nid, unsigned long start_pfn,
798                 unsigned long nr_pages)
799 {
800         struct pglist_data *pgdat = NODE_DATA(nid);
801         int zid;
802 
803         for (zid = 0; zid <= ZONE_NORMAL; zid++) {
804                 struct zone *zone = &pgdat->node_zones[zid];
805 
806                 if (zone_intersects(zone, start_pfn, nr_pages))
807                         return zone;
808         }
809 
810         return &pgdat->node_zones[ZONE_NORMAL];
811 }
812 
813 static inline struct zone *default_zone_for_pfn(int nid, unsigned long start_pfn,
814                 unsigned long nr_pages)
815 {
816         struct zone *kernel_zone = default_kernel_zone_for_pfn(nid, start_pfn,
817                         nr_pages);
818         struct zone *movable_zone = &NODE_DATA(nid)->node_zones[ZONE_MOVABLE];
819         bool in_kernel = zone_intersects(kernel_zone, start_pfn, nr_pages);
820         bool in_movable = zone_intersects(movable_zone, start_pfn, nr_pages);
821 
822         /*
823          * We inherit the existing zone in a simple case where zones do not
824          * overlap in the given range
825          */
826         if (in_kernel ^ in_movable)
827                 return (in_kernel) ? kernel_zone : movable_zone;
828 
829         /*
830          * If the range doesn't belong to any zone or two zones overlap in the
831          * given range then we use movable zone only if movable_node is
832          * enabled because we always online to a kernel zone by default.
833          */
834         return movable_node_enabled ? movable_zone : kernel_zone;
835 }
836 
837 struct zone *zone_for_pfn_range(int online_type, int nid,
838                 unsigned long start_pfn, unsigned long nr_pages)
839 {
840         if (online_type == MMOP_ONLINE_KERNEL)
841                 return default_kernel_zone_for_pfn(nid, start_pfn, nr_pages);
842 
843         if (online_type == MMOP_ONLINE_MOVABLE)
844                 return &NODE_DATA(nid)->node_zones[ZONE_MOVABLE];
845 
846         return default_zone_for_pfn(nid, start_pfn, nr_pages);
847 }
848 
849 /*
850  * This function should only be called by memory_block_{online,offline},
851  * and {online,offline}_pages.
852  */
853 void adjust_present_page_count(struct zone *zone, long nr_pages)
854 {
855         unsigned long flags;
856 
857         zone->present_pages += nr_pages;
858         pgdat_resize_lock(zone->zone_pgdat, &flags);
859         zone->zone_pgdat->node_present_pages += nr_pages;
860         pgdat_resize_unlock(zone->zone_pgdat, &flags);
861 }
862 
863 int mhp_init_memmap_on_memory(unsigned long pfn, unsigned long nr_pages,
864                               struct zone *zone)
865 {
866         unsigned long end_pfn = pfn + nr_pages;
867         int ret;
868 
869         ret = kasan_add_zero_shadow(__va(PFN_PHYS(pfn)), PFN_PHYS(nr_pages));
870         if (ret)
871                 return ret;
872 
873         move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_UNMOVABLE);
874 
875         /*
876          * It might be that the vmemmap_pages fully span sections. If that is
877          * the case, mark those sections online here as otherwise they will be
878          * left offline.
879          */
880         if (nr_pages >= PAGES_PER_SECTION)
881                 online_mem_sections(pfn, ALIGN_DOWN(end_pfn, PAGES_PER_SECTION));
882 
883         return ret;
884 }
885 
886 void mhp_deinit_memmap_on_memory(unsigned long pfn, unsigned long nr_pages)
887 {
888         unsigned long end_pfn = pfn + nr_pages;
889 
890         /*
891          * It might be that the vmemmap_pages fully span sections. If that is
892          * the case, mark those sections offline here as otherwise they will be
893          * left online.
894          */
895         if (nr_pages >= PAGES_PER_SECTION)
896                 offline_mem_sections(pfn, ALIGN_DOWN(end_pfn, PAGES_PER_SECTION));
897 
898         /*
899          * The pages associated with this vmemmap have been offlined, so
900          * we can reset its state here.
901          */
902         remove_pfn_range_from_zone(page_zone(pfn_to_page(pfn)), pfn, nr_pages);
903         kasan_remove_zero_shadow(__va(PFN_PHYS(pfn)), PFN_PHYS(nr_pages));
904 }
905 
906 int __ref online_pages(unsigned long pfn, unsigned long nr_pages, struct zone *zone)
907 {
908         unsigned long flags;
909         int need_zonelists_rebuild = 0;
910         const int nid = zone_to_nid(zone);
911         int ret;
912         struct memory_notify arg;
913 
914         /*
915          * {on,off}lining is constrained to full memory sections (or more
916          * precisly to memory blocks from the user space POV).
917          * memmap_on_memory is an exception because it reserves initial part
918          * of the physical memory space for vmemmaps. That space is pageblock
919          * aligned.
920          */
921         if (WARN_ON_ONCE(!nr_pages ||
922                          !IS_ALIGNED(pfn, pageblock_nr_pages) ||
923                          !IS_ALIGNED(pfn + nr_pages, PAGES_PER_SECTION)))
924                 return -EINVAL;
925 
926         mem_hotplug_begin();
927 
928         /* associate pfn range with the zone */
929         move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_ISOLATE);
930 
931         arg.start_pfn = pfn;
932         arg.nr_pages = nr_pages;
933         node_states_check_changes_online(nr_pages, zone, &arg);
934 
935         ret = memory_notify(MEM_GOING_ONLINE, &arg);
936         ret = notifier_to_errno(ret);
937         if (ret)
938                 goto failed_addition;
939 
940         /*
941          * Fixup the number of isolated pageblocks before marking the sections
942          * onlining, such that undo_isolate_page_range() works correctly.
943          */
944         spin_lock_irqsave(&zone->lock, flags);
945         zone->nr_isolate_pageblock += nr_pages / pageblock_nr_pages;
946         spin_unlock_irqrestore(&zone->lock, flags);
947 
948         /*
949          * If this zone is not populated, then it is not in zonelist.
950          * This means the page allocator ignores this zone.
951          * So, zonelist must be updated after online.
952          */
953         if (!populated_zone(zone)) {
954                 need_zonelists_rebuild = 1;
955                 setup_zone_pageset(zone);
956         }
957 
958         online_pages_range(pfn, nr_pages);
959         adjust_present_page_count(zone, nr_pages);
960 
961         node_states_set_node(nid, &arg);
962         if (need_zonelists_rebuild)
963                 build_all_zonelists(NULL);
964         zone_pcp_update(zone);
965 
966         /* Basic onlining is complete, allow allocation of onlined pages. */
967         undo_isolate_page_range(pfn, pfn + nr_pages, MIGRATE_MOVABLE);
968 
969         /*
970          * Freshly onlined pages aren't shuffled (e.g., all pages are placed to
971          * the tail of the freelist when undoing isolation). Shuffle the whole
972          * zone to make sure the just onlined pages are properly distributed
973          * across the whole freelist - to create an initial shuffle.
974          */
975         shuffle_zone(zone);
976 
977         init_per_zone_wmark_min();
978 
979         kswapd_run(nid);
980         kcompactd_run(nid);
981 
982         writeback_set_ratelimit();
983 
984         memory_notify(MEM_ONLINE, &arg);
985         mem_hotplug_done();
986         return 0;
987 
988 failed_addition:
989         pr_debug("online_pages [mem %#010llx-%#010llx] failed\n",
990                  (unsigned long long) pfn << PAGE_SHIFT,
991                  (((unsigned long long) pfn + nr_pages) << PAGE_SHIFT) - 1);
992         memory_notify(MEM_CANCEL_ONLINE, &arg);
993         remove_pfn_range_from_zone(zone, pfn, nr_pages);
994         mem_hotplug_done();
995         return ret;
996 }
997 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
998 
999 static void reset_node_present_pages(pg_data_t *pgdat)
1000 {
1001         struct zone *z;
1002 
1003         for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
1004                 z->present_pages = 0;
1005 
1006         pgdat->node_present_pages = 0;
1007 }
1008 
1009 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
1010 static pg_data_t __ref *hotadd_new_pgdat(int nid)
1011 {
1012         struct pglist_data *pgdat;
1013 
1014         pgdat = NODE_DATA(nid);
1015         if (!pgdat) {
1016                 pgdat = arch_alloc_nodedata(nid);
1017                 if (!pgdat)
1018                         return NULL;
1019 
1020                 pgdat->per_cpu_nodestats =
1021                         alloc_percpu(struct per_cpu_nodestat);
1022                 arch_refresh_nodedata(nid, pgdat);
1023         } else {
1024                 int cpu;
1025                 /*
1026                  * Reset the nr_zones, order and highest_zoneidx before reuse.
1027                  * Note that kswapd will init kswapd_highest_zoneidx properly
1028                  * when it starts in the near future.
1029                  */
1030                 pgdat->nr_zones = 0;
1031                 pgdat->kswapd_order = 0;
1032                 pgdat->kswapd_highest_zoneidx = 0;
1033                 for_each_online_cpu(cpu) {
1034                         struct per_cpu_nodestat *p;
1035 
1036                         p = per_cpu_ptr(pgdat->per_cpu_nodestats, cpu);
1037                         memset(p, 0, sizeof(*p));
1038                 }
1039         }
1040 
1041         /* we can use NODE_DATA(nid) from here */
1042         pgdat->node_id = nid;
1043         pgdat->node_start_pfn = 0;
1044 
1045         /* init node's zones as empty zones, we don't have any present pages.*/
1046         free_area_init_core_hotplug(nid);
1047 
1048         /*
1049          * The node we allocated has no zone fallback lists. For avoiding
1050          * to access not-initialized zonelist, build here.
1051          */
1052         build_all_zonelists(pgdat);
1053 
1054         /*
1055          * When memory is hot-added, all the memory is in offline state. So
1056          * clear all zones' present_pages because they will be updated in
1057          * online_pages() and offline_pages().
1058          */
1059         reset_node_managed_pages(pgdat);
1060         reset_node_present_pages(pgdat);
1061 
1062         return pgdat;
1063 }
1064 
1065 static void rollback_node_hotadd(int nid)
1066 {
1067         pg_data_t *pgdat = NODE_DATA(nid);
1068 
1069         arch_refresh_nodedata(nid, NULL);
1070         free_percpu(pgdat->per_cpu_nodestats);
1071         arch_free_nodedata(pgdat);
1072 }
1073 
1074 
1075 /**
1076  * try_online_node - online a node if offlined
1077  * @nid: the node ID
1078  * @set_node_online: Whether we want to online the node
1079  * called by cpu_up() to online a node without onlined memory.
1080  *
1081  * Returns:
1082  * 1 -> a new node has been allocated
1083  * 0 -> the node is already online
1084  * -ENOMEM -> the node could not be allocated
1085  */
1086 static int __try_online_node(int nid, bool set_node_online)
1087 {
1088         pg_data_t *pgdat;
1089         int ret = 1;
1090 
1091         if (node_online(nid))
1092                 return 0;
1093 
1094         pgdat = hotadd_new_pgdat(nid);
1095         if (!pgdat) {
1096                 pr_err("Cannot online node %d due to NULL pgdat\n", nid);
1097                 ret = -ENOMEM;
1098                 goto out;
1099         }
1100 
1101         if (set_node_online) {
1102                 node_set_online(nid);
1103                 ret = register_one_node(nid);
1104                 BUG_ON(ret);
1105         }
1106 out:
1107         return ret;
1108 }
1109 
1110 /*
1111  * Users of this function always want to online/register the node
1112  */
1113 int try_online_node(int nid)
1114 {
1115         int ret;
1116 
1117         mem_hotplug_begin();
1118         ret =  __try_online_node(nid, true);
1119         mem_hotplug_done();
1120         return ret;
1121 }
1122 
1123 static int check_hotplug_memory_range(u64 start, u64 size)
1124 {
1125         /* memory range must be block size aligned */
1126         if (!size || !IS_ALIGNED(start, memory_block_size_bytes()) ||
1127             !IS_ALIGNED(size, memory_block_size_bytes())) {
1128                 pr_err("Block size [%#lx] unaligned hotplug range: start %#llx, size %#llx",
1129                        memory_block_size_bytes(), start, size);
1130                 return -EINVAL;
1131         }
1132 
1133         return 0;
1134 }
1135 
1136 static int online_memory_block(struct memory_block *mem, void *arg)
1137 {
1138         mem->online_type = mhp_default_online_type;
1139         return device_online(&mem->dev);
1140 }
1141 
1142 bool mhp_supports_memmap_on_memory(unsigned long size)
1143 {
1144         unsigned long nr_vmemmap_pages = size / PAGE_SIZE;
1145         unsigned long vmemmap_size = nr_vmemmap_pages * sizeof(struct page);
1146         unsigned long remaining_size = size - vmemmap_size;
1147 
1148         /*
1149          * Besides having arch support and the feature enabled at runtime, we
1150          * need a few more assumptions to hold true:
1151          *
1152          * a) We span a single memory block: memory onlining/offlinin;g happens
1153          *    in memory block granularity. We don't want the vmemmap of online
1154          *    memory blocks to reside on offline memory blocks. In the future,
1155          *    we might want to support variable-sized memory blocks to make the
1156          *    feature more versatile.
1157          *
1158          * b) The vmemmap pages span complete PMDs: We don't want vmemmap code
1159          *    to populate memory from the altmap for unrelated parts (i.e.,
1160          *    other memory blocks)
1161          *
1162          * c) The vmemmap pages (and thereby the pages that will be exposed to
1163          *    the buddy) have to cover full pageblocks: memory onlining/offlining
1164          *    code requires applicable ranges to be page-aligned, for example, to
1165          *    set the migratetypes properly.
1166          *
1167          * TODO: Although we have a check here to make sure that vmemmap pages
1168          *       fully populate a PMD, it is not the right place to check for
1169          *       this. A much better solution involves improving vmemmap code
1170          *       to fallback to base pages when trying to populate vmemmap using
1171          *       altmap as an alternative source of memory, and we do not exactly
1172          *       populate a single PMD.
1173          */
1174         return memmap_on_memory &&
1175                IS_ENABLED(CONFIG_MHP_MEMMAP_ON_MEMORY) &&
1176                size == memory_block_size_bytes() &&
1177                IS_ALIGNED(vmemmap_size, PMD_SIZE) &&
1178                IS_ALIGNED(remaining_size, (pageblock_nr_pages << PAGE_SHIFT));
1179 }
1180 
1181 /*
1182  * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
1183  * and online/offline operations (triggered e.g. by sysfs).
1184  *
1185  * we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG
1186  */
1187 int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
1188 {
1189         struct mhp_params params = { .pgprot = pgprot_mhp(PAGE_KERNEL) };
1190         struct vmem_altmap mhp_altmap = {};
1191         u64 start, size;
1192         bool new_node = false;
1193         int ret;
1194 
1195         start = res->start;
1196         size = resource_size(res);
1197 
1198         ret = check_hotplug_memory_range(start, size);
1199         if (ret)
1200                 return ret;
1201 
1202         if (!node_possible(nid)) {
1203                 WARN(1, "node %d was absent from the node_possible_map\n", nid);
1204                 return -EINVAL;
1205         }
1206 
1207         mem_hotplug_begin();
1208 
1209         if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
1210                 memblock_add_node(start, size, nid);
1211 
1212         ret = __try_online_node(nid, false);
1213         if (ret < 0)
1214                 goto error;
1215         new_node = ret;
1216 
1217         /*
1218          * Self hosted memmap array
1219          */
1220         if (mhp_flags & MHP_MEMMAP_ON_MEMORY) {
1221                 if (!mhp_supports_memmap_on_memory(size)) {
1222                         ret = -EINVAL;
1223                         goto error;
1224                 }
1225                 mhp_altmap.free = PHYS_PFN(size);
1226                 mhp_altmap.base_pfn = PHYS_PFN(start);
1227                 params.altmap = &mhp_altmap;
1228         }
1229 
1230         /* call arch's memory hotadd */
1231         ret = arch_add_memory(nid, start, size, &params);
1232         if (ret < 0)
1233                 goto error;
1234 
1235         /* create memory block devices after memory was added */
1236         ret = create_memory_block_devices(start, size, mhp_altmap.alloc);
1237         if (ret) {
1238                 arch_remove_memory(nid, start, size, NULL);
1239                 goto error;
1240         }
1241 
1242         if (new_node) {
1243                 /* If sysfs file of new node can't be created, cpu on the node
1244                  * can't be hot-added. There is no rollback way now.
1245                  * So, check by BUG_ON() to catch it reluctantly..
1246                  * We online node here. We can't roll back from here.
1247                  */
1248                 node_set_online(nid);
1249                 ret = __register_one_node(nid);
1250                 BUG_ON(ret);
1251         }
1252 
1253         /* link memory sections under this node.*/
1254         link_mem_sections(nid, PFN_DOWN(start), PFN_UP(start + size - 1),
1255                           MEMINIT_HOTPLUG);
1256 
1257         /* create new memmap entry */
1258         if (!strcmp(res->name, "System RAM"))
1259                 firmware_map_add_hotplug(start, start + size, "System RAM");
1260 
1261         /* device_online() will take the lock when calling online_pages() */
1262         mem_hotplug_done();
1263 
1264         /*
1265          * In case we're allowed to merge the resource, flag it and trigger
1266          * merging now that adding succeeded.
1267          */
1268         if (mhp_flags & MHP_MERGE_RESOURCE)
1269                 merge_system_ram_resource(res);
1270 
1271         /* online pages if requested */
1272         if (mhp_default_online_type != MMOP_OFFLINE)
1273                 walk_memory_blocks(start, size, NULL, online_memory_block);
1274 
1275         return ret;
1276 error:
1277         /* rollback pgdat allocation and others */
1278         if (new_node)
1279                 rollback_node_hotadd(nid);
1280         if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
1281                 memblock_remove(start, size);
1282         mem_hotplug_done();
1283         return ret;
1284 }
1285 
1286 /* requires device_hotplug_lock, see add_memory_resource() */
1287 int __ref __add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags)
1288 {
1289         struct resource *res;
1290         int ret;
1291 
1292         res = register_memory_resource(start, size, "System RAM");
1293         if (IS_ERR(res))
1294                 return PTR_ERR(res);
1295 
1296         ret = add_memory_resource(nid, res, mhp_flags);
1297         if (ret < 0)
1298                 release_memory_resource(res);
1299         return ret;
1300 }
1301 
1302 int add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags)
1303 {
1304         int rc;
1305 
1306         lock_device_hotplug();
1307         rc = __add_memory(nid, start, size, mhp_flags);
1308         unlock_device_hotplug();
1309 
1310         return rc;
1311 }
1312 EXPORT_SYMBOL_GPL(add_memory);
1313 
1314 /*
1315  * Add special, driver-managed memory to the system as system RAM. Such
1316  * memory is not exposed via the raw firmware-provided memmap as system
1317  * RAM, instead, it is detected and added by a driver - during cold boot,
1318  * after a reboot, and after kexec.
1319  *
1320  * Reasons why this memory should not be used for the initial memmap of a
1321  * kexec kernel or for placing kexec images:
1322  * - The booting kernel is in charge of determining how this memory will be
1323  *   used (e.g., use persistent memory as system RAM)
1324  * - Coordination with a hypervisor is required before this memory
1325  *   can be used (e.g., inaccessible parts).
1326  *
1327  * For this memory, no entries in /sys/firmware/memmap ("raw firmware-provided
1328  * memory map") are created. Also, the created memory resource is flagged
1329  * with IORESOURCE_SYSRAM_DRIVER_MANAGED, so in-kernel users can special-case
1330  * this memory as well (esp., not place kexec images onto it).
1331  *
1332  * The resource_name (visible via /proc/iomem) has to have the format
1333  * "System RAM ($DRIVER)".
1334  */
1335 int add_memory_driver_managed(int nid, u64 start, u64 size,
1336                               const char *resource_name, mhp_t mhp_flags)
1337 {
1338         struct resource *res;
1339         int rc;
1340 
1341         if (!resource_name ||
1342             strstr(resource_name, "System RAM (") != resource_name ||
1343             resource_name[strlen(resource_name) - 1] != ')')
1344                 return -EINVAL;
1345 
1346         lock_device_hotplug();
1347 
1348         res = register_memory_resource(start, size, resource_name);
1349         if (IS_ERR(res)) {
1350                 rc = PTR_ERR(res);
1351                 goto out_unlock;
1352         }
1353 
1354         rc = add_memory_resource(nid, res, mhp_flags);
1355         if (rc < 0)
1356                 release_memory_resource(res);
1357 
1358 out_unlock:
1359         unlock_device_hotplug();
1360         return rc;
1361 }
1362 EXPORT_SYMBOL_GPL(add_memory_driver_managed);
1363 
1364 /*
1365  * Platforms should define arch_get_mappable_range() that provides
1366  * maximum possible addressable physical memory range for which the
1367  * linear mapping could be created. The platform returned address
1368  * range must adhere to these following semantics.
1369  *
1370  * - range.start <= range.end
1371  * - Range includes both end points [range.start..range.end]
1372  *
1373  * There is also a fallback definition provided here, allowing the
1374  * entire possible physical address range in case any platform does
1375  * not define arch_get_mappable_range().
1376  */
1377 struct range __weak arch_get_mappable_range(void)
1378 {
1379         struct range mhp_range = {
1380                 .start = 0UL,
1381                 .end = -1ULL,
1382         };
1383         return mhp_range;
1384 }
1385 
1386 struct range mhp_get_pluggable_range(bool need_mapping)
1387 {
1388         const u64 max_phys = (1ULL << MAX_PHYSMEM_BITS) - 1;
1389         struct range mhp_range;
1390 
1391         if (need_mapping) {
1392                 mhp_range = arch_get_mappable_range();
1393                 if (mhp_range.start > max_phys) {
1394                         mhp_range.start = 0;
1395                         mhp_range.end = 0;
1396                 }
1397                 mhp_range.end = min_t(u64, mhp_range.end, max_phys);
1398         } else {
1399                 mhp_range.start = 0;
1400                 mhp_range.end = max_phys;
1401         }
1402         return mhp_range;
1403 }
1404 EXPORT_SYMBOL_GPL(mhp_get_pluggable_range);
1405 
1406 bool mhp_range_allowed(u64 start, u64 size, bool need_mapping)
1407 {
1408         struct range mhp_range = mhp_get_pluggable_range(need_mapping);
1409         u64 end = start + size;
1410 
1411         if (start < end && start >= mhp_range.start && (end - 1) <= mhp_range.end)
1412                 return true;
1413 
1414         pr_warn("Hotplug memory [%#llx-%#llx] exceeds maximum addressable range [%#llx-%#llx]\n",
1415                 start, end, mhp_range.start, mhp_range.end);
1416         return false;
1417 }
1418 
1419 #ifdef CONFIG_MEMORY_HOTREMOVE
1420 /*
1421  * Confirm all pages in a range [start, end) belong to the same zone (skipping
1422  * memory holes). When true, return the zone.
1423  */
1424 struct zone *test_pages_in_a_zone(unsigned long start_pfn,
1425                                   unsigned long end_pfn)
1426 {
1427         unsigned long pfn, sec_end_pfn;
1428         struct zone *zone = NULL;
1429         struct page *page;
1430         int i;
1431         for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn + 1);
1432              pfn < end_pfn;
1433              pfn = sec_end_pfn, sec_end_pfn += PAGES_PER_SECTION) {
1434                 /* Make sure the memory section is present first */
1435                 if (!present_section_nr(pfn_to_section_nr(pfn)))
1436                         continue;
1437                 for (; pfn < sec_end_pfn && pfn < end_pfn;
1438                      pfn += MAX_ORDER_NR_PAGES) {
1439                         i = 0;
1440                         /* This is just a CONFIG_HOLES_IN_ZONE check.*/
1441                         while ((i < MAX_ORDER_NR_PAGES) &&
1442                                 !pfn_valid_within(pfn + i))
1443                                 i++;
1444                         if (i == MAX_ORDER_NR_PAGES || pfn + i >= end_pfn)
1445                                 continue;
1446                         /* Check if we got outside of the zone */
1447                         if (zone && !zone_spans_pfn(zone, pfn + i))
1448                                 return NULL;
1449                         page = pfn_to_page(pfn + i);
1450                         if (zone && page_zone(page) != zone)
1451                                 return NULL;
1452                         zone = page_zone(page);
1453                 }
1454         }
1455 
1456         return zone;
1457 }
1458 
1459 /*
1460  * Scan pfn range [start,end) to find movable/migratable pages (LRU pages,
1461  * non-lru movable pages and hugepages). Will skip over most unmovable
1462  * pages (esp., pages that can be skipped when offlining), but bail out on
1463  * definitely unmovable pages.
1464  *
1465  * Returns:
1466  *      0 in case a movable page is found and movable_pfn was updated.
1467  *      -ENOENT in case no movable page was found.
1468  *      -EBUSY in case a definitely unmovable page was found.
1469  */
1470 static int scan_movable_pages(unsigned long start, unsigned long end,
1471                               unsigned long *movable_pfn)
1472 {
1473         unsigned long pfn;
1474 
1475         for (pfn = start; pfn < end; pfn++) {
1476                 struct page *page, *head;
1477                 unsigned long skip;
1478 
1479                 if (!pfn_valid(pfn))
1480                         continue;
1481                 page = pfn_to_page(pfn);
1482                 if (PageLRU(page))
1483                         goto found;
1484                 if (__PageMovable(page))
1485                         goto found;
1486 
1487                 /*
1488                  * PageOffline() pages that are not marked __PageMovable() and
1489                  * have a reference count > 0 (after MEM_GOING_OFFLINE) are
1490                  * definitely unmovable. If their reference count would be 0,
1491                  * they could at least be skipped when offlining memory.
1492                  */
1493                 if (PageOffline(page) && page_count(page))
1494                         return -EBUSY;
1495 
1496                 if (!PageHuge(page))
1497                         continue;
1498                 head = compound_head(page);
1499                 /*
1500                  * This test is racy as we hold no reference or lock.  The
1501                  * hugetlb page could have been free'ed and head is no longer
1502                  * a hugetlb page before the following check.  In such unlikely
1503                  * cases false positives and negatives are possible.  Calling
1504                  * code must deal with these scenarios.
1505                  */
1506                 if (HPageMigratable(head))
1507                         goto found;
1508                 skip = compound_nr(head) - (page - head);
1509                 pfn += skip - 1;
1510         }
1511         return -ENOENT;
1512 found:
1513         *movable_pfn = pfn;
1514         return 0;
1515 }
1516 
1517 static int
1518 do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
1519 {
1520         unsigned long pfn;
1521         struct page *page, *head;
1522         int ret = 0;
1523         LIST_HEAD(source);
1524 
1525         for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1526                 if (!pfn_valid(pfn))
1527                         continue;
1528                 page = pfn_to_page(pfn);
1529                 head = compound_head(page);
1530 
1531                 if (PageHuge(page)) {
1532                         pfn = page_to_pfn(head) + compound_nr(head) - 1;
1533                         isolate_huge_page(head, &source);
1534                         continue;
1535                 } else if (PageTransHuge(page))
1536                         pfn = page_to_pfn(head) + thp_nr_pages(page) - 1;
1537 
1538                 /*
1539                  * HWPoison pages have elevated reference counts so the migration would
1540                  * fail on them. It also doesn't make any sense to migrate them in the
1541                  * first place. Still try to unmap such a page in case it is still mapped
1542                  * (e.g. current hwpoison implementation doesn't unmap KSM pages but keep
1543                  * the unmap as the catch all safety net).
1544                  */
1545                 if (PageHWPoison(page)) {
1546                         if (WARN_ON(PageLRU(page)))
1547                                 isolate_lru_page(page);
1548                         if (page_mapped(page))
1549                                 try_to_unmap(page, TTU_IGNORE_MLOCK);
1550                         continue;
1551                 }
1552 
1553                 if (!get_page_unless_zero(page))
1554                         continue;
1555                 /*
1556                  * We can skip free pages. And we can deal with pages on
1557                  * LRU and non-lru movable pages.
1558                  */
1559                 if (PageLRU(page))
1560                         ret = isolate_lru_page(page);
1561                 else
1562                         ret = isolate_movable_page(page, ISOLATE_UNEVICTABLE);
1563                 if (!ret) { /* Success */
1564                         list_add_tail(&page->lru, &source);
1565                         if (!__PageMovable(page))
1566                                 inc_node_page_state(page, NR_ISOLATED_ANON +
1567                                                     page_is_file_lru(page));
1568 
1569                 } else {
1570                         pr_warn("failed to isolate pfn %lx\n", pfn);
1571                         dump_page(page, "isolation failed");
1572                 }
1573                 put_page(page);
1574         }
1575         if (!list_empty(&source)) {
1576                 nodemask_t nmask = node_states[N_MEMORY];
1577                 struct migration_target_control mtc = {
1578                         .nmask = &nmask,
1579                         .gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
1580                 };
1581 
1582                 /*
1583                  * We have checked that migration range is on a single zone so
1584                  * we can use the nid of the first page to all the others.
1585                  */
1586                 mtc.nid = page_to_nid(list_first_entry(&source, struct page, lru));
1587 
1588                 /*
1589                  * try to allocate from a different node but reuse this node
1590                  * if there are no other online nodes to be used (e.g. we are
1591                  * offlining a part of the only existing node)
1592                  */
1593                 node_clear(mtc.nid, nmask);
1594                 if (nodes_empty(nmask))
1595                         node_set(mtc.nid, nmask);
1596                 ret = migrate_pages(&source, alloc_migration_target, NULL,
1597                         (unsigned long)&mtc, MIGRATE_SYNC, MR_MEMORY_HOTPLUG);
1598                 if (ret) {
1599                         list_for_each_entry(page, &source, lru) {
1600                                 pr_warn("migrating pfn %lx failed ret:%d ",
1601                                        page_to_pfn(page), ret);
1602                                 dump_page(page, "migration failure");
1603                         }
1604                         putback_movable_pages(&source);
1605                 }
1606         }
1607 
1608         return ret;
1609 }
1610 
1611 static int __init cmdline_parse_movable_node(char *p)
1612 {
1613         movable_node_enabled = true;
1614         return 0;
1615 }
1616 early_param("movable_node", cmdline_parse_movable_node);
1617 
1618 /* check which state of node_states will be changed when offline memory */
1619 static void node_states_check_changes_offline(unsigned long nr_pages,
1620                 struct zone *zone, struct memory_notify *arg)
1621 {
1622         struct pglist_data *pgdat = zone->zone_pgdat;
1623         unsigned long present_pages = 0;
1624         enum zone_type zt;
1625 
1626         arg->status_change_nid = NUMA_NO_NODE;
1627         arg->status_change_nid_normal = NUMA_NO_NODE;
1628         arg->status_change_nid_high = NUMA_NO_NODE;
1629 
1630         /*
1631          * Check whether node_states[N_NORMAL_MEMORY] will be changed.
1632          * If the memory to be offline is within the range
1633          * [0..ZONE_NORMAL], and it is the last present memory there,
1634          * the zones in that range will become empty after the offlining,
1635          * thus we can determine that we need to clear the node from
1636          * node_states[N_NORMAL_MEMORY].
1637          */
1638         for (zt = 0; zt <= ZONE_NORMAL; zt++)
1639                 present_pages += pgdat->node_zones[zt].present_pages;
1640         if (zone_idx(zone) <= ZONE_NORMAL && nr_pages >= present_pages)
1641                 arg->status_change_nid_normal = zone_to_nid(zone);
1642 
1643 #ifdef CONFIG_HIGHMEM
1644         /*
1645          * node_states[N_HIGH_MEMORY] contains nodes which
1646          * have normal memory or high memory.
1647          * Here we add the present_pages belonging to ZONE_HIGHMEM.
1648          * If the zone is within the range of [0..ZONE_HIGHMEM), and
1649          * we determine that the zones in that range become empty,
1650          * we need to clear the node for N_HIGH_MEMORY.
1651          */
1652         present_pages += pgdat->node_zones[ZONE_HIGHMEM].present_pages;
1653         if (zone_idx(zone) <= ZONE_HIGHMEM && nr_pages >= present_pages)
1654                 arg->status_change_nid_high = zone_to_nid(zone);
1655 #endif
1656 
1657         /*
1658          * We have accounted the pages from [0..ZONE_NORMAL), and
1659          * in case of CONFIG_HIGHMEM the pages from ZONE_HIGHMEM
1660          * as well.
1661          * Here we count the possible pages from ZONE_MOVABLE.
1662          * If after having accounted all the pages, we see that the nr_pages
1663          * to be offlined is over or equal to the accounted pages,
1664          * we know that the node will become empty, and so, we can clear
1665          * it for N_MEMORY as well.
1666          */
1667         present_pages += pgdat->node_zones[ZONE_MOVABLE].present_pages;
1668 
1669         if (nr_pages >= present_pages)
1670                 arg->status_change_nid = zone_to_nid(zone);
1671 }
1672 
1673 static void node_states_clear_node(int node, struct memory_notify *arg)
1674 {
1675         if (arg->status_change_nid_normal >= 0)
1676                 node_clear_state(node, N_NORMAL_MEMORY);
1677 
1678         if (arg->status_change_nid_high >= 0)
1679                 node_clear_state(node, N_HIGH_MEMORY);
1680 
1681         if (arg->status_change_nid >= 0)
1682                 node_clear_state(node, N_MEMORY);
1683 }
1684 
1685 static int count_system_ram_pages_cb(unsigned long start_pfn,
1686                                      unsigned long nr_pages, void *data)
1687 {
1688         unsigned long *nr_system_ram_pages = data;
1689 
1690         *nr_system_ram_pages += nr_pages;
1691         return 0;
1692 }
1693 
1694 int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
1695 {
1696         const unsigned long end_pfn = start_pfn + nr_pages;
1697         unsigned long pfn, system_ram_pages = 0;
1698         unsigned long flags;
1699         struct zone *zone;
1700         struct memory_notify arg;
1701         int ret, node;
1702         char *reason;
1703 
1704         /*
1705          * {on,off}lining is constrained to full memory sections (or more
1706          * precisly to memory blocks from the user space POV).
1707          * memmap_on_memory is an exception because it reserves initial part
1708          * of the physical memory space for vmemmaps. That space is pageblock
1709          * aligned.
1710          */
1711         if (WARN_ON_ONCE(!nr_pages ||
1712                          !IS_ALIGNED(start_pfn, pageblock_nr_pages) ||
1713                          !IS_ALIGNED(start_pfn + nr_pages, PAGES_PER_SECTION)))
1714                 return -EINVAL;
1715 
1716         mem_hotplug_begin();
1717 
1718         /*
1719          * Don't allow to offline memory blocks that contain holes.
1720          * Consequently, memory blocks with holes can never get onlined
1721          * via the hotplug path - online_pages() - as hotplugged memory has
1722          * no holes. This way, we e.g., don't have to worry about marking
1723          * memory holes PG_reserved, don't need pfn_valid() checks, and can
1724          * avoid using walk_system_ram_range() later.
1725          */
1726         walk_system_ram_range(start_pfn, nr_pages, &system_ram_pages,
1727                               count_system_ram_pages_cb);
1728         if (system_ram_pages != nr_pages) {
1729                 ret = -EINVAL;
1730                 reason = "memory holes";
1731                 goto failed_removal;
1732         }
1733 
1734         /* This makes hotplug much easier...and readable.
1735            we assume this for now. .*/
1736         zone = test_pages_in_a_zone(start_pfn, end_pfn);
1737         if (!zone) {
1738                 ret = -EINVAL;
1739                 reason = "multizone range";
1740                 goto failed_removal;
1741         }
1742         node = zone_to_nid(zone);
1743 
1744         /*
1745          * Disable pcplists so that page isolation cannot race with freeing
1746          * in a way that pages from isolated pageblock are left on pcplists.
1747          */
1748         zone_pcp_disable(zone);
1749         lru_cache_disable();
1750 
1751         /* set above range as isolated */
1752         ret = start_isolate_page_range(start_pfn, end_pfn,
1753                                        MIGRATE_MOVABLE,
1754                                        MEMORY_OFFLINE | REPORT_FAILURE);
1755         if (ret) {
1756                 reason = "failure to isolate range";
1757                 goto failed_removal_pcplists_disabled;
1758         }
1759 
1760         arg.start_pfn = start_pfn;
1761         arg.nr_pages = nr_pages;
1762         node_states_check_changes_offline(nr_pages, zone, &arg);
1763 
1764         ret = memory_notify(MEM_GOING_OFFLINE, &arg);
1765         ret = notifier_to_errno(ret);
1766         if (ret) {
1767                 reason = "notifier failure";
1768                 goto failed_removal_isolated;
1769         }
1770 
1771         do {
1772                 pfn = start_pfn;
1773                 do {
1774                         if (signal_pending(current)) {
1775                                 ret = -EINTR;
1776                                 reason = "signal backoff";
1777                                 goto failed_removal_isolated;
1778                         }
1779 
1780                         cond_resched();
1781 
1782                         ret = scan_movable_pages(pfn, end_pfn, &pfn);
1783                         if (!ret) {
1784                                 /*
1785                                  * TODO: fatal migration failures should bail
1786                                  * out
1787                                  */
1788                                 do_migrate_range(pfn, end_pfn);
1789                         }
1790                 } while (!ret);
1791 
1792                 if (ret != -ENOENT) {
1793                         reason = "unmovable page";
1794                         goto failed_removal_isolated;
1795                 }
1796 
1797                 /*
1798                  * Dissolve free hugepages in the memory block before doing
1799                  * offlining actually in order to make hugetlbfs's object
1800                  * counting consistent.
1801                  */
1802                 ret = dissolve_free_huge_pages(start_pfn, end_pfn);
1803                 if (ret) {
1804                         reason = "failure to dissolve huge pages";
1805                         goto failed_removal_isolated;
1806                 }
1807 
1808                 ret = test_pages_isolated(start_pfn, end_pfn, MEMORY_OFFLINE);
1809 
1810         } while (ret);
1811 
1812         /* Mark all sections offline and remove free pages from the buddy. */
1813         __offline_isolated_pages(start_pfn, end_pfn);
1814         pr_debug("Offlined Pages %ld\n", nr_pages);
1815 
1816         /*
1817          * The memory sections are marked offline, and the pageblock flags
1818          * effectively stale; nobody should be touching them. Fixup the number
1819          * of isolated pageblocks, memory onlining will properly revert this.
1820          */
1821         spin_lock_irqsave(&zone->lock, flags);
1822         zone->nr_isolate_pageblock -= nr_pages / pageblock_nr_pages;
1823         spin_unlock_irqrestore(&zone->lock, flags);
1824 
1825         lru_cache_enable();
1826         zone_pcp_enable(zone);
1827 
1828         /* removal success */
1829         adjust_managed_page_count(pfn_to_page(start_pfn), -nr_pages);
1830         adjust_present_page_count(zone, -nr_pages);
1831 
1832         init_per_zone_wmark_min();
1833 
1834         if (!populated_zone(zone)) {
1835                 zone_pcp_reset(zone);
1836                 build_all_zonelists(NULL);
1837         } else
1838                 zone_pcp_update(zone);
1839 
1840         node_states_clear_node(node, &arg);
1841         if (arg.status_change_nid >= 0) {
1842                 kswapd_stop(node);
1843                 kcompactd_stop(node);
1844         }
1845 
1846         writeback_set_ratelimit();
1847 
1848         memory_notify(MEM_OFFLINE, &arg);
1849         remove_pfn_range_from_zone(zone, start_pfn, nr_pages);
1850         mem_hotplug_done();
1851         return 0;
1852 
1853 failed_removal_isolated:
1854         undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
1855         memory_notify(MEM_CANCEL_OFFLINE, &arg);
1856 failed_removal_pcplists_disabled:
1857         lru_cache_enable();
1858         zone_pcp_enable(zone);
1859 failed_removal:
1860         pr_debug("memory offlining [mem %#010llx-%#010llx] failed due to %s\n",
1861                  (unsigned long long) start_pfn << PAGE_SHIFT,
1862                  ((unsigned long long) end_pfn << PAGE_SHIFT) - 1,
1863                  reason);
1864         /* pushback to free area */
1865         mem_hotplug_done();
1866         return ret;
1867 }
1868 
1869 static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)
1870 {
1871         int ret = !is_memblock_offlined(mem);
1872 
1873         if (unlikely(ret)) {
1874                 phys_addr_t beginpa, endpa;
1875 
1876                 beginpa = PFN_PHYS(section_nr_to_pfn(mem->start_section_nr));
1877                 endpa = beginpa + memory_block_size_bytes() - 1;
1878                 pr_warn("removing memory fails, because memory [%pa-%pa] is onlined\n",
1879                         &beginpa, &endpa);
1880 
1881                 return -EBUSY;
1882         }
1883         return 0;
1884 }
1885 
1886 static int get_nr_vmemmap_pages_cb(struct memory_block *mem, void *arg)
1887 {
1888         /*
1889          * If not set, continue with the next block.
1890          */
1891         return mem->nr_vmemmap_pages;
1892 }
1893 
1894 static int check_cpu_on_node(pg_data_t *pgdat)
1895 {
1896         int cpu;
1897 
1898         for_each_present_cpu(cpu) {
1899                 if (cpu_to_node(cpu) == pgdat->node_id)
1900                         /*
1901                          * the cpu on this node isn't removed, and we can't
1902                          * offline this node.
1903                          */
1904                         return -EBUSY;
1905         }
1906 
1907         return 0;
1908 }
1909 
1910 static int check_no_memblock_for_node_cb(struct memory_block *mem, void *arg)
1911 {
1912         int nid = *(int *)arg;
1913 
1914         /*
1915          * If a memory block belongs to multiple nodes, the stored nid is not
1916          * reliable. However, such blocks are always online (e.g., cannot get
1917          * offlined) and, therefore, are still spanned by the node.
1918          */
1919         return mem->nid == nid ? -EEXIST : 0;
1920 }
1921 
1922 /**
1923  * try_offline_node
1924  * @nid: the node ID
1925  *
1926  * Offline a node if all memory sections and cpus of the node are removed.
1927  *
1928  * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
1929  * and online/offline operations before this call.
1930  */
1931 void try_offline_node(int nid)
1932 {
1933         pg_data_t *pgdat = NODE_DATA(nid);
1934         int rc;
1935 
1936         /*
1937          * If the node still spans pages (especially ZONE_DEVICE), don't
1938          * offline it. A node spans memory after move_pfn_range_to_zone(),
1939          * e.g., after the memory block was onlined.
1940          */
1941         if (pgdat->node_spanned_pages)
1942                 return;
1943 
1944         /*
1945          * Especially offline memory blocks might not be spanned by the
1946          * node. They will get spanned by the node once they get onlined.
1947          * However, they link to the node in sysfs and can get onlined later.
1948          */
1949         rc = for_each_memory_block(&nid, check_no_memblock_for_node_cb);
1950         if (rc)
1951                 return;
1952 
1953         if (check_cpu_on_node(pgdat))
1954                 return;
1955 
1956         /*
1957          * all memory/cpu of this node are removed, we can offline this
1958          * node now.
1959          */
1960         node_set_offline(nid);
1961         unregister_one_node(nid);
1962 }
1963 EXPORT_SYMBOL(try_offline_node);
1964 
1965 static int __ref try_remove_memory(int nid, u64 start, u64 size)
1966 {
1967         int rc = 0;
1968         struct vmem_altmap mhp_altmap = {};
1969         struct vmem_altmap *altmap = NULL;
1970         unsigned long nr_vmemmap_pages;
1971 
1972         BUG_ON(check_hotplug_memory_range(start, size));
1973 
1974         /*
1975          * All memory blocks must be offlined before removing memory.  Check
1976          * whether all memory blocks in question are offline and return error
1977          * if this is not the case.
1978          */
1979         rc = walk_memory_blocks(start, size, NULL, check_memblock_offlined_cb);
1980         if (rc)
1981                 return rc;
1982 
1983         /*
1984          * We only support removing memory added with MHP_MEMMAP_ON_MEMORY in
1985          * the same granularity it was added - a single memory block.
1986          */
1987         if (memmap_on_memory) {
1988                 nr_vmemmap_pages = walk_memory_blocks(start, size, NULL,
1989                                                       get_nr_vmemmap_pages_cb);
1990                 if (nr_vmemmap_pages) {
1991                         if (size != memory_block_size_bytes()) {
1992                                 pr_warn("Refuse to remove %#llx - %#llx,"
1993                                         "wrong granularity\n",
1994                                         start, start + size);
1995                                 return -EINVAL;
1996                         }
1997 
1998                         /*
1999                          * Let remove_pmd_table->free_hugepage_table do the
2000                          * right thing if we used vmem_altmap when hot-adding
2001                          * the range.
2002                          */
2003                         mhp_altmap.alloc = nr_vmemmap_pages;
2004                         altmap = &mhp_altmap;
2005                 }
2006         }
2007 
2008         /* remove memmap entry */
2009         firmware_map_remove(start, start + size, "System RAM");
2010 
2011         /*
2012          * Memory block device removal under the device_hotplug_lock is
2013          * a barrier against racing online attempts.
2014          */
2015         remove_memory_block_devices(start, size);
2016 
2017         mem_hotplug_begin();
2018 
2019         arch_remove_memory(nid, start, size, altmap);
2020 
2021         if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {
2022                 memblock_free(start, size);
2023                 memblock_remove(start, size);
2024         }
2025 
2026         release_mem_region_adjustable(start, size);
2027 
2028         try_offline_node(nid);
2029 
2030         mem_hotplug_done();
2031         return 0;
2032 }
2033 
2034 /**
2035  * remove_memory
2036  * @nid: the node ID
2037  * @start: physical address of the region to remove
2038  * @size: size of the region to remove
2039  *
2040  * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
2041  * and online/offline operations before this call, as required by
2042  * try_offline_node().
2043  */
2044 void __remove_memory(int nid, u64 start, u64 size)
2045 {
2046 
2047         /*
2048          * trigger BUG() if some memory is not offlined prior to calling this
2049          * function
2050          */
2051         if (try_remove_memory(nid, start, size))
2052                 BUG();
2053 }
2054 
2055 /*
2056  * Remove memory if every memory block is offline, otherwise return -EBUSY is
2057  * some memory is not offline
2058  */
2059 int remove_memory(int nid, u64 start, u64 size)
2060 {
2061         int rc;
2062 
2063         lock_device_hotplug();
2064         rc  = try_remove_memory(nid, start, size);
2065         unlock_device_hotplug();
2066 
2067         return rc;
2068 }
2069 EXPORT_SYMBOL_GPL(remove_memory);
2070 
2071 static int try_offline_memory_block(struct memory_block *mem, void *arg)
2072 {
2073         uint8_t online_type = MMOP_ONLINE_KERNEL;
2074         uint8_t **online_types = arg;
2075         struct page *page;
2076         int rc;
2077 
2078         /*
2079          * Sense the online_type via the zone of the memory block. Offlining
2080          * with multiple zones within one memory block will be rejected
2081          * by offlining code ... so we don't care about that.
2082          */
2083         page = pfn_to_online_page(section_nr_to_pfn(mem->start_section_nr));
2084         if (page && zone_idx(page_zone(page)) == ZONE_MOVABLE)
2085                 online_type = MMOP_ONLINE_MOVABLE;
2086 
2087         rc = device_offline(&mem->dev);
2088         /*
2089          * Default is MMOP_OFFLINE - change it only if offlining succeeded,
2090          * so try_reonline_memory_block() can do the right thing.
2091          */
2092         if (!rc)
2093                 **online_types = online_type;
2094 
2095         (*online_types)++;
2096         /* Ignore if already offline. */
2097         return rc < 0 ? rc : 0;
2098 }
2099 
2100 static int try_reonline_memory_block(struct memory_block *mem, void *arg)
2101 {
2102         uint8_t **online_types = arg;
2103         int rc;
2104 
2105         if (**online_types != MMOP_OFFLINE) {
2106                 mem->online_type = **online_types;
2107                 rc = device_online(&mem->dev);
2108                 if (rc < 0)
2109                         pr_warn("%s: Failed to re-online memory: %d",
2110                                 __func__, rc);
2111         }
2112 
2113         /* Continue processing all remaining memory blocks. */
2114         (*online_types)++;
2115         return 0;
2116 }
2117 
2118 /*
2119  * Try to offline and remove memory. Might take a long time to finish in case
2120  * memory is still in use. Primarily useful for memory devices that logically
2121  * unplugged all memory (so it's no longer in use) and want to offline + remove
2122  * that memory.
2123  */
2124 int offline_and_remove_memory(int nid, u64 start, u64 size)
2125 {
2126         const unsigned long mb_count = size / memory_block_size_bytes();
2127         uint8_t *online_types, *tmp;
2128         int rc;
2129 
2130         if (!IS_ALIGNED(start, memory_block_size_bytes()) ||
2131             !IS_ALIGNED(size, memory_block_size_bytes()) || !size)
2132                 return -EINVAL;
2133 
2134         /*
2135          * We'll remember the old online type of each memory block, so we can
2136          * try to revert whatever we did when offlining one memory block fails
2137          * after offlining some others succeeded.
2138          */
2139         online_types = kmalloc_array(mb_count, sizeof(*online_types),
2140                                      GFP_KERNEL);
2141         if (!online_types)
2142                 return -ENOMEM;
2143         /*
2144          * Initialize all states to MMOP_OFFLINE, so when we abort processing in
2145          * try_offline_memory_block(), we'll skip all unprocessed blocks in
2146          * try_reonline_memory_block().
2147          */
2148         memset(online_types, MMOP_OFFLINE, mb_count);
2149 
2150         lock_device_hotplug();
2151 
2152         tmp = online_types;
2153         rc = walk_memory_blocks(start, size, &tmp, try_offline_memory_block);
2154 
2155         /*
2156          * In case we succeeded to offline all memory, remove it.
2157          * This cannot fail as it cannot get onlined in the meantime.
2158          */
2159         if (!rc) {
2160                 rc = try_remove_memory(nid, start, size);
2161                 if (rc)
2162                         pr_err("%s: Failed to remove memory: %d", __func__, rc);
2163         }
2164 
2165         /*
2166          * Rollback what we did. While memory onlining might theoretically fail
2167          * (nacked by a notifier), it barely ever happens.
2168          */
2169         if (rc) {
2170                 tmp = online_types;
2171                 walk_memory_blocks(start, size, &tmp,
2172                                    try_reonline_memory_block);
2173         }
2174         unlock_device_hotplug();
2175 
2176         kfree(online_types);
2177         return rc;
2178 }
2179 EXPORT_SYMBOL_GPL(offline_and_remove_memory);
2180 #endif /* CONFIG_MEMORY_HOTREMOVE */
2181 

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