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 */
  49static bool memmap_on_memory __ro_after_init;
  50#ifdef CONFIG_MHP_MEMMAP_ON_MEMORY
  51module_param(memmap_on_memory, bool, 0444);
  52MODULE_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
  62static online_page_callback_t online_page_callback = generic_online_page;
  63static DEFINE_MUTEX(online_page_callback_lock);
  64
  65DEFINE_STATIC_PERCPU_RWSEM(mem_hotplug_lock);
  66
  67void get_online_mems(void)
  68{
  69	percpu_down_read(&mem_hotplug_lock);
  70}
  71
  72void put_online_mems(void)
  73{
  74	percpu_up_read(&mem_hotplug_lock);
  75}
  76
  77bool movable_node_enabled = false;
  78
  79#ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
  80int mhp_default_online_type = MMOP_OFFLINE;
  81#else
  82int mhp_default_online_type = MMOP_ONLINE;
  83#endif
  84
  85static 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
  96void mem_hotplug_begin(void)
  97{
  98	cpus_read_lock();
  99	percpu_down_write(&mem_hotplug_lock);
 100}
 101
 102void mem_hotplug_done(void)
 103{
 104	percpu_up_write(&mem_hotplug_lock);
 105	cpus_read_unlock();
 106}
 107
 108u64 max_mem_size = U64_MAX;
 109
 110/* add this memory to iomem resource */
 111static 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
 148static 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
 157static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
 158		const char *reason)
 159{
 160	/*
 161	 * Disallow all operations smaller than a sub-section and only
 162	 * allow operations smaller than a section for
 163	 * SPARSEMEM_VMEMMAP. Note that check_hotplug_memory_range()
 164	 * enforces a larger memory_block_size_bytes() granularity for
 165	 * memory that will be marked online, so this check should only
 166	 * fire for direct arch_{add,remove}_memory() users outside of
 167	 * add_memory_resource().
 168	 */
 169	unsigned long min_align;
 170
 171	if (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP))
 172		min_align = PAGES_PER_SUBSECTION;
 173	else
 174		min_align = PAGES_PER_SECTION;
 175	if (!IS_ALIGNED(pfn, min_align)
 176			|| !IS_ALIGNED(nr_pages, min_align)) {
 177		WARN(1, "Misaligned __%s_pages start: %#lx end: #%lx\n",
 178				reason, pfn, pfn + nr_pages - 1);
 179		return -EINVAL;
 180	}
 181	return 0;
 182}
 183
 184/*
 185 * Return page for the valid pfn only if the page is online. All pfn
 186 * walkers which rely on the fully initialized page->flags and others
 187 * should use this rather than pfn_valid && pfn_to_page
 188 */
 189struct page *pfn_to_online_page(unsigned long pfn)
 190{
 191	unsigned long nr = pfn_to_section_nr(pfn);
 192	struct dev_pagemap *pgmap;
 193	struct mem_section *ms;
 194
 195	if (nr >= NR_MEM_SECTIONS)
 196		return NULL;
 197
 198	ms = __nr_to_section(nr);
 199	if (!online_section(ms))
 200		return NULL;
 201
 202	/*
 203	 * Save some code text when online_section() +
 204	 * pfn_section_valid() are sufficient.
 205	 */
 206	if (IS_ENABLED(CONFIG_HAVE_ARCH_PFN_VALID) && !pfn_valid(pfn))
 207		return NULL;
 208
 209	if (!pfn_section_valid(ms, pfn))
 210		return NULL;
 211
 212	if (!online_device_section(ms))
 213		return pfn_to_page(pfn);
 214
 215	/*
 216	 * Slowpath: when ZONE_DEVICE collides with
 217	 * ZONE_{NORMAL,MOVABLE} within the same section some pfns in
 218	 * the section may be 'offline' but 'valid'. Only
 219	 * get_dev_pagemap() can determine sub-section online status.
 220	 */
 221	pgmap = get_dev_pagemap(pfn, NULL);
 222	put_dev_pagemap(pgmap);
 223
 224	/* The presence of a pgmap indicates ZONE_DEVICE offline pfn */
 225	if (pgmap)
 226		return NULL;
 227
 228	return pfn_to_page(pfn);
 229}
 230EXPORT_SYMBOL_GPL(pfn_to_online_page);
 231
 232/*
 233 * Reasonably generic function for adding memory.  It is
 234 * expected that archs that support memory hotplug will
 235 * call this function after deciding the zone to which to
 236 * add the new pages.
 237 */
 238int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
 239		struct mhp_params *params)
 240{
 241	const unsigned long end_pfn = pfn + nr_pages;
 242	unsigned long cur_nr_pages;
 243	int err;
 244	struct vmem_altmap *altmap = params->altmap;
 245
 246	if (WARN_ON_ONCE(!params->pgprot.pgprot))
 247		return -EINVAL;
 248
 249	VM_BUG_ON(!mhp_range_allowed(PFN_PHYS(pfn), nr_pages * PAGE_SIZE, false));
 250
 251	if (altmap) {
 252		/*
 253		 * Validate altmap is within bounds of the total request
 254		 */
 255		if (altmap->base_pfn != pfn
 256				|| vmem_altmap_offset(altmap) > nr_pages) {
 257			pr_warn_once("memory add fail, invalid altmap\n");
 258			return -EINVAL;
 259		}
 260		altmap->alloc = 0;
 261	}
 262
 263	err = check_pfn_span(pfn, nr_pages, "add");
 264	if (err)
 265		return err;
 
 266
 267	for (; pfn < end_pfn; pfn += cur_nr_pages) {
 268		/* Select all remaining pages up to the next section boundary */
 269		cur_nr_pages = min(end_pfn - pfn,
 270				   SECTION_ALIGN_UP(pfn + 1) - pfn);
 271		err = sparse_add_section(nid, pfn, cur_nr_pages, altmap);
 
 272		if (err)
 273			break;
 274		cond_resched();
 275	}
 276	vmemmap_populate_print_last();
 277	return err;
 278}
 279
 280/* find the smallest valid pfn in the range [start_pfn, end_pfn) */
 281static unsigned long find_smallest_section_pfn(int nid, struct zone *zone,
 282				     unsigned long start_pfn,
 283				     unsigned long end_pfn)
 284{
 285	for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SUBSECTION) {
 286		if (unlikely(!pfn_to_online_page(start_pfn)))
 287			continue;
 288
 289		if (unlikely(pfn_to_nid(start_pfn) != nid))
 290			continue;
 291
 292		if (zone != page_zone(pfn_to_page(start_pfn)))
 293			continue;
 294
 295		return start_pfn;
 296	}
 297
 298	return 0;
 299}
 300
 301/* find the biggest valid pfn in the range [start_pfn, end_pfn). */
 302static unsigned long find_biggest_section_pfn(int nid, struct zone *zone,
 303				    unsigned long start_pfn,
 304				    unsigned long end_pfn)
 305{
 306	unsigned long pfn;
 307
 308	/* pfn is the end pfn of a memory section. */
 309	pfn = end_pfn - 1;
 310	for (; pfn >= start_pfn; pfn -= PAGES_PER_SUBSECTION) {
 311		if (unlikely(!pfn_to_online_page(pfn)))
 312			continue;
 313
 314		if (unlikely(pfn_to_nid(pfn) != nid))
 315			continue;
 316
 317		if (zone != page_zone(pfn_to_page(pfn)))
 318			continue;
 319
 320		return pfn;
 321	}
 322
 323	return 0;
 324}
 325
 326static void shrink_zone_span(struct zone *zone, unsigned long start_pfn,
 327			     unsigned long end_pfn)
 328{
 329	unsigned long pfn;
 330	int nid = zone_to_nid(zone);
 331
 332	if (zone->zone_start_pfn == start_pfn) {
 333		/*
 334		 * If the section is smallest section in the zone, it need
 335		 * shrink zone->zone_start_pfn and zone->zone_spanned_pages.
 336		 * In this case, we find second smallest valid mem_section
 337		 * for shrinking zone.
 338		 */
 339		pfn = find_smallest_section_pfn(nid, zone, end_pfn,
 340						zone_end_pfn(zone));
 341		if (pfn) {
 342			zone->spanned_pages = zone_end_pfn(zone) - pfn;
 343			zone->zone_start_pfn = pfn;
 344		} else {
 345			zone->zone_start_pfn = 0;
 346			zone->spanned_pages = 0;
 347		}
 348	} else if (zone_end_pfn(zone) == end_pfn) {
 349		/*
 350		 * If the section is biggest section in the zone, it need
 351		 * shrink zone->spanned_pages.
 352		 * In this case, we find second biggest valid mem_section for
 353		 * shrinking zone.
 354		 */
 355		pfn = find_biggest_section_pfn(nid, zone, zone->zone_start_pfn,
 356					       start_pfn);
 357		if (pfn)
 358			zone->spanned_pages = pfn - zone->zone_start_pfn + 1;
 359		else {
 360			zone->zone_start_pfn = 0;
 361			zone->spanned_pages = 0;
 362		}
 363	}
 364}
 365
 366static void update_pgdat_span(struct pglist_data *pgdat)
 367{
 368	unsigned long node_start_pfn = 0, node_end_pfn = 0;
 369	struct zone *zone;
 370
 371	for (zone = pgdat->node_zones;
 372	     zone < pgdat->node_zones + MAX_NR_ZONES; zone++) {
 373		unsigned long end_pfn = zone_end_pfn(zone);
 374
 375		/* No need to lock the zones, they can't change. */
 376		if (!zone->spanned_pages)
 377			continue;
 378		if (!node_end_pfn) {
 379			node_start_pfn = zone->zone_start_pfn;
 380			node_end_pfn = end_pfn;
 381			continue;
 382		}
 383
 384		if (end_pfn > node_end_pfn)
 385			node_end_pfn = end_pfn;
 386		if (zone->zone_start_pfn < node_start_pfn)
 387			node_start_pfn = zone->zone_start_pfn;
 388	}
 389
 390	pgdat->node_start_pfn = node_start_pfn;
 391	pgdat->node_spanned_pages = node_end_pfn - node_start_pfn;
 392}
 393
 394void __ref remove_pfn_range_from_zone(struct zone *zone,
 395				      unsigned long start_pfn,
 396				      unsigned long nr_pages)
 397{
 398	const unsigned long end_pfn = start_pfn + nr_pages;
 399	struct pglist_data *pgdat = zone->zone_pgdat;
 400	unsigned long pfn, cur_nr_pages;
 401
 402	/* Poison struct pages because they are now uninitialized again. */
 403	for (pfn = start_pfn; pfn < end_pfn; pfn += cur_nr_pages) {
 404		cond_resched();
 405
 406		/* Select all remaining pages up to the next section boundary */
 407		cur_nr_pages =
 408			min(end_pfn - pfn, SECTION_ALIGN_UP(pfn + 1) - pfn);
 409		page_init_poison(pfn_to_page(pfn),
 410				 sizeof(struct page) * cur_nr_pages);
 411	}
 412
 413#ifdef CONFIG_ZONE_DEVICE
 414	/*
 415	 * Zone shrinking code cannot properly deal with ZONE_DEVICE. So
 416	 * we will not try to shrink the zones - which is okay as
 417	 * set_zone_contiguous() cannot deal with ZONE_DEVICE either way.
 418	 */
 419	if (zone_idx(zone) == ZONE_DEVICE)
 420		return;
 421#endif
 422
 423	clear_zone_contiguous(zone);
 424
 425	shrink_zone_span(zone, start_pfn, start_pfn + nr_pages);
 426	update_pgdat_span(pgdat);
 427
 428	set_zone_contiguous(zone);
 429}
 430
 431static void __remove_section(unsigned long pfn, unsigned long nr_pages,
 432			     unsigned long map_offset,
 433			     struct vmem_altmap *altmap)
 434{
 435	struct mem_section *ms = __pfn_to_section(pfn);
 436
 437	if (WARN_ON_ONCE(!valid_section(ms)))
 438		return;
 439
 440	sparse_remove_section(ms, pfn, nr_pages, map_offset, altmap);
 441}
 442
 443/**
 444 * __remove_pages() - remove sections of pages
 445 * @pfn: starting pageframe (must be aligned to start of a section)
 446 * @nr_pages: number of pages to remove (must be multiple of section size)
 447 * @altmap: alternative device page map or %NULL if default memmap is used
 448 *
 449 * Generic helper function to remove section mappings and sysfs entries
 450 * for the section of the memory we are removing. Caller needs to make
 451 * sure that pages are marked reserved and zones are adjust properly by
 452 * calling offline_pages().
 453 */
 454void __remove_pages(unsigned long pfn, unsigned long nr_pages,
 455		    struct vmem_altmap *altmap)
 456{
 457	const unsigned long end_pfn = pfn + nr_pages;
 458	unsigned long cur_nr_pages;
 459	unsigned long map_offset = 0;
 460
 461	map_offset = vmem_altmap_offset(altmap);
 462
 463	if (check_pfn_span(pfn, nr_pages, "remove"))
 
 464		return;
 
 465
 466	for (; pfn < end_pfn; pfn += cur_nr_pages) {
 467		cond_resched();
 468		/* Select all remaining pages up to the next section boundary */
 469		cur_nr_pages = min(end_pfn - pfn,
 470				   SECTION_ALIGN_UP(pfn + 1) - pfn);
 471		__remove_section(pfn, cur_nr_pages, map_offset, altmap);
 472		map_offset = 0;
 473	}
 474}
 475
 476int set_online_page_callback(online_page_callback_t callback)
 477{
 478	int rc = -EINVAL;
 479
 480	get_online_mems();
 481	mutex_lock(&online_page_callback_lock);
 482
 483	if (online_page_callback == generic_online_page) {
 484		online_page_callback = callback;
 485		rc = 0;
 486	}
 487
 488	mutex_unlock(&online_page_callback_lock);
 489	put_online_mems();
 490
 491	return rc;
 492}
 493EXPORT_SYMBOL_GPL(set_online_page_callback);
 494
 495int restore_online_page_callback(online_page_callback_t callback)
 496{
 497	int rc = -EINVAL;
 498
 499	get_online_mems();
 500	mutex_lock(&online_page_callback_lock);
 501
 502	if (online_page_callback == callback) {
 503		online_page_callback = generic_online_page;
 504		rc = 0;
 505	}
 506
 507	mutex_unlock(&online_page_callback_lock);
 508	put_online_mems();
 509
 510	return rc;
 511}
 512EXPORT_SYMBOL_GPL(restore_online_page_callback);
 513
 514void generic_online_page(struct page *page, unsigned int order)
 515{
 516	/*
 517	 * Freeing the page with debug_pagealloc enabled will try to unmap it,
 518	 * so we should map it first. This is better than introducing a special
 519	 * case in page freeing fast path.
 520	 */
 521	debug_pagealloc_map_pages(page, 1 << order);
 522	__free_pages_core(page, order);
 523	totalram_pages_add(1UL << order);
 524#ifdef CONFIG_HIGHMEM
 525	if (PageHighMem(page))
 526		totalhigh_pages_add(1UL << order);
 527#endif
 528}
 529EXPORT_SYMBOL_GPL(generic_online_page);
 530
 531static void online_pages_range(unsigned long start_pfn, unsigned long nr_pages)
 532{
 533	const unsigned long end_pfn = start_pfn + nr_pages;
 534	unsigned long pfn;
 535
 536	/*
 537	 * Online the pages in MAX_ORDER - 1 aligned chunks. The callback might
 538	 * decide to not expose all pages to the buddy (e.g., expose them
 539	 * later). We account all pages as being online and belonging to this
 540	 * zone ("present").
 541	 * When using memmap_on_memory, the range might not be aligned to
 542	 * MAX_ORDER_NR_PAGES - 1, but pageblock aligned. __ffs() will detect
 543	 * this and the first chunk to online will be pageblock_nr_pages.
 544	 */
 545	for (pfn = start_pfn; pfn < end_pfn;) {
 546		int order = min(MAX_ORDER - 1UL, __ffs(pfn));
 
 
 
 
 
 
 
 
 
 
 
 
 547
 548		(*online_page_callback)(pfn_to_page(pfn), order);
 549		pfn += (1UL << order);
 550	}
 551
 552	/* mark all involved sections as online */
 553	online_mem_sections(start_pfn, end_pfn);
 554}
 555
 556/* check which state of node_states will be changed when online memory */
 557static void node_states_check_changes_online(unsigned long nr_pages,
 558	struct zone *zone, struct memory_notify *arg)
 559{
 560	int nid = zone_to_nid(zone);
 561
 562	arg->status_change_nid = NUMA_NO_NODE;
 563	arg->status_change_nid_normal = NUMA_NO_NODE;
 564	arg->status_change_nid_high = NUMA_NO_NODE;
 565
 566	if (!node_state(nid, N_MEMORY))
 567		arg->status_change_nid = nid;
 568	if (zone_idx(zone) <= ZONE_NORMAL && !node_state(nid, N_NORMAL_MEMORY))
 569		arg->status_change_nid_normal = nid;
 570#ifdef CONFIG_HIGHMEM
 571	if (zone_idx(zone) <= ZONE_HIGHMEM && !node_state(nid, N_HIGH_MEMORY))
 572		arg->status_change_nid_high = nid;
 573#endif
 574}
 575
 576static void node_states_set_node(int node, struct memory_notify *arg)
 577{
 578	if (arg->status_change_nid_normal >= 0)
 579		node_set_state(node, N_NORMAL_MEMORY);
 580
 581	if (arg->status_change_nid_high >= 0)
 582		node_set_state(node, N_HIGH_MEMORY);
 583
 584	if (arg->status_change_nid >= 0)
 585		node_set_state(node, N_MEMORY);
 586}
 587
 588static void __meminit resize_zone_range(struct zone *zone, unsigned long start_pfn,
 589		unsigned long nr_pages)
 590{
 591	unsigned long old_end_pfn = zone_end_pfn(zone);
 592
 593	if (zone_is_empty(zone) || start_pfn < zone->zone_start_pfn)
 594		zone->zone_start_pfn = start_pfn;
 595
 596	zone->spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - zone->zone_start_pfn;
 597}
 598
 599static void __meminit resize_pgdat_range(struct pglist_data *pgdat, unsigned long start_pfn,
 600                                     unsigned long nr_pages)
 601{
 602	unsigned long old_end_pfn = pgdat_end_pfn(pgdat);
 603
 604	if (!pgdat->node_spanned_pages || start_pfn < pgdat->node_start_pfn)
 605		pgdat->node_start_pfn = start_pfn;
 606
 607	pgdat->node_spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - pgdat->node_start_pfn;
 608
 609}
 610
 
 611static void section_taint_zone_device(unsigned long pfn)
 612{
 613	struct mem_section *ms = __pfn_to_section(pfn);
 614
 615	ms->section_mem_map |= SECTION_TAINT_ZONE_DEVICE;
 616}
 
 
 
 
 
 617
 618/*
 619 * Associate the pfn range with the given zone, initializing the memmaps
 620 * and resizing the pgdat/zone data to span the added pages. After this
 621 * call, all affected pages are PG_reserved.
 622 *
 623 * All aligned pageblocks are initialized to the specified migratetype
 624 * (usually MIGRATE_MOVABLE). Besides setting the migratetype, no related
 625 * zone stats (e.g., nr_isolate_pageblock) are touched.
 626 */
 627void __ref move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
 628				  unsigned long nr_pages,
 629				  struct vmem_altmap *altmap, int migratetype)
 630{
 631	struct pglist_data *pgdat = zone->zone_pgdat;
 632	int nid = pgdat->node_id;
 633
 634	clear_zone_contiguous(zone);
 635
 636	if (zone_is_empty(zone))
 637		init_currently_empty_zone(zone, start_pfn, nr_pages);
 638	resize_zone_range(zone, start_pfn, nr_pages);
 639	resize_pgdat_range(pgdat, start_pfn, nr_pages);
 640
 641	/*
 642	 * Subsection population requires care in pfn_to_online_page().
 643	 * Set the taint to enable the slow path detection of
 644	 * ZONE_DEVICE pages in an otherwise  ZONE_{NORMAL,MOVABLE}
 645	 * section.
 646	 */
 647	if (zone_is_zone_device(zone)) {
 648		if (!IS_ALIGNED(start_pfn, PAGES_PER_SECTION))
 649			section_taint_zone_device(start_pfn);
 650		if (!IS_ALIGNED(start_pfn + nr_pages, PAGES_PER_SECTION))
 651			section_taint_zone_device(start_pfn + nr_pages);
 652	}
 653
 654	/*
 655	 * TODO now we have a visible range of pages which are not associated
 656	 * with their zone properly. Not nice but set_pfnblock_flags_mask
 657	 * expects the zone spans the pfn range. All the pages in the range
 658	 * are reserved so nobody should be touching them so we should be safe
 659	 */
 660	memmap_init_range(nr_pages, nid, zone_idx(zone), start_pfn, 0,
 661			 MEMINIT_HOTPLUG, altmap, migratetype);
 662
 663	set_zone_contiguous(zone);
 664}
 665
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 666/*
 667 * Returns a default kernel memory zone for the given pfn range.
 668 * If no kernel zone covers this pfn range it will automatically go
 669 * to the ZONE_NORMAL.
 670 */
 671static struct zone *default_kernel_zone_for_pfn(int nid, unsigned long start_pfn,
 672		unsigned long nr_pages)
 673{
 674	struct pglist_data *pgdat = NODE_DATA(nid);
 675	int zid;
 676
 677	for (zid = 0; zid <= ZONE_NORMAL; zid++) {
 678		struct zone *zone = &pgdat->node_zones[zid];
 679
 680		if (zone_intersects(zone, start_pfn, nr_pages))
 681			return zone;
 682	}
 683
 684	return &pgdat->node_zones[ZONE_NORMAL];
 685}
 686
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 687static inline struct zone *default_zone_for_pfn(int nid, unsigned long start_pfn,
 688		unsigned long nr_pages)
 689{
 690	struct zone *kernel_zone = default_kernel_zone_for_pfn(nid, start_pfn,
 691			nr_pages);
 692	struct zone *movable_zone = &NODE_DATA(nid)->node_zones[ZONE_MOVABLE];
 693	bool in_kernel = zone_intersects(kernel_zone, start_pfn, nr_pages);
 694	bool in_movable = zone_intersects(movable_zone, start_pfn, nr_pages);
 695
 696	/*
 697	 * We inherit the existing zone in a simple case where zones do not
 698	 * overlap in the given range
 699	 */
 700	if (in_kernel ^ in_movable)
 701		return (in_kernel) ? kernel_zone : movable_zone;
 702
 703	/*
 704	 * If the range doesn't belong to any zone or two zones overlap in the
 705	 * given range then we use movable zone only if movable_node is
 706	 * enabled because we always online to a kernel zone by default.
 707	 */
 708	return movable_node_enabled ? movable_zone : kernel_zone;
 709}
 710
 711struct zone *zone_for_pfn_range(int online_type, int nid,
 712		unsigned long start_pfn, unsigned long nr_pages)
 
 713{
 714	if (online_type == MMOP_ONLINE_KERNEL)
 715		return default_kernel_zone_for_pfn(nid, start_pfn, nr_pages);
 716
 717	if (online_type == MMOP_ONLINE_MOVABLE)
 718		return &NODE_DATA(nid)->node_zones[ZONE_MOVABLE];
 719
 
 
 
 720	return default_zone_for_pfn(nid, start_pfn, nr_pages);
 721}
 722
 723/*
 724 * This function should only be called by memory_block_{online,offline},
 725 * and {online,offline}_pages.
 726 */
 727void adjust_present_page_count(struct zone *zone, long nr_pages)
 
 728{
 
 
 
 
 
 
 
 
 
 729	zone->present_pages += nr_pages;
 730	zone->zone_pgdat->node_present_pages += nr_pages;
 
 
 
 
 
 731}
 732
 733int mhp_init_memmap_on_memory(unsigned long pfn, unsigned long nr_pages,
 734			      struct zone *zone)
 735{
 736	unsigned long end_pfn = pfn + nr_pages;
 737	int ret;
 738
 739	ret = kasan_add_zero_shadow(__va(PFN_PHYS(pfn)), PFN_PHYS(nr_pages));
 740	if (ret)
 741		return ret;
 742
 743	move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_UNMOVABLE);
 744
 
 
 
 745	/*
 746	 * It might be that the vmemmap_pages fully span sections. If that is
 747	 * the case, mark those sections online here as otherwise they will be
 748	 * left offline.
 749	 */
 750	if (nr_pages >= PAGES_PER_SECTION)
 751	        online_mem_sections(pfn, ALIGN_DOWN(end_pfn, PAGES_PER_SECTION));
 752
 753	return ret;
 754}
 755
 756void mhp_deinit_memmap_on_memory(unsigned long pfn, unsigned long nr_pages)
 757{
 758	unsigned long end_pfn = pfn + nr_pages;
 759
 760	/*
 761	 * It might be that the vmemmap_pages fully span sections. If that is
 762	 * the case, mark those sections offline here as otherwise they will be
 763	 * left online.
 764	 */
 765	if (nr_pages >= PAGES_PER_SECTION)
 766		offline_mem_sections(pfn, ALIGN_DOWN(end_pfn, PAGES_PER_SECTION));
 767
 768        /*
 769	 * The pages associated with this vmemmap have been offlined, so
 770	 * we can reset its state here.
 771	 */
 772	remove_pfn_range_from_zone(page_zone(pfn_to_page(pfn)), pfn, nr_pages);
 773	kasan_remove_zero_shadow(__va(PFN_PHYS(pfn)), PFN_PHYS(nr_pages));
 774}
 775
 776int __ref online_pages(unsigned long pfn, unsigned long nr_pages, struct zone *zone)
 
 
 
 
 777{
 778	unsigned long flags;
 779	int need_zonelists_rebuild = 0;
 780	const int nid = zone_to_nid(zone);
 781	int ret;
 782	struct memory_notify arg;
 783
 784	/*
 785	 * {on,off}lining is constrained to full memory sections (or more
 786	 * precisely to memory blocks from the user space POV).
 787	 * memmap_on_memory is an exception because it reserves initial part
 788	 * of the physical memory space for vmemmaps. That space is pageblock
 789	 * aligned.
 790	 */
 791	if (WARN_ON_ONCE(!nr_pages ||
 792			 !IS_ALIGNED(pfn, pageblock_nr_pages) ||
 793			 !IS_ALIGNED(pfn + nr_pages, PAGES_PER_SECTION)))
 794		return -EINVAL;
 795
 796	mem_hotplug_begin();
 797
 798	/* associate pfn range with the zone */
 799	move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_ISOLATE);
 800
 801	arg.start_pfn = pfn;
 802	arg.nr_pages = nr_pages;
 803	node_states_check_changes_online(nr_pages, zone, &arg);
 804
 805	ret = memory_notify(MEM_GOING_ONLINE, &arg);
 806	ret = notifier_to_errno(ret);
 807	if (ret)
 808		goto failed_addition;
 809
 810	/*
 811	 * Fixup the number of isolated pageblocks before marking the sections
 812	 * onlining, such that undo_isolate_page_range() works correctly.
 813	 */
 814	spin_lock_irqsave(&zone->lock, flags);
 815	zone->nr_isolate_pageblock += nr_pages / pageblock_nr_pages;
 816	spin_unlock_irqrestore(&zone->lock, flags);
 817
 818	/*
 819	 * If this zone is not populated, then it is not in zonelist.
 820	 * This means the page allocator ignores this zone.
 821	 * So, zonelist must be updated after online.
 822	 */
 823	if (!populated_zone(zone)) {
 824		need_zonelists_rebuild = 1;
 825		setup_zone_pageset(zone);
 826	}
 827
 828	online_pages_range(pfn, nr_pages);
 829	adjust_present_page_count(zone, nr_pages);
 830
 831	node_states_set_node(nid, &arg);
 832	if (need_zonelists_rebuild)
 833		build_all_zonelists(NULL);
 834
 835	/* Basic onlining is complete, allow allocation of onlined pages. */
 836	undo_isolate_page_range(pfn, pfn + nr_pages, MIGRATE_MOVABLE);
 837
 838	/*
 839	 * Freshly onlined pages aren't shuffled (e.g., all pages are placed to
 840	 * the tail of the freelist when undoing isolation). Shuffle the whole
 841	 * zone to make sure the just onlined pages are properly distributed
 842	 * across the whole freelist - to create an initial shuffle.
 843	 */
 844	shuffle_zone(zone);
 845
 846	/* reinitialise watermarks and update pcp limits */
 847	init_per_zone_wmark_min();
 848
 849	kswapd_run(nid);
 850	kcompactd_run(nid);
 851
 852	writeback_set_ratelimit();
 853
 854	memory_notify(MEM_ONLINE, &arg);
 855	mem_hotplug_done();
 856	return 0;
 857
 858failed_addition:
 859	pr_debug("online_pages [mem %#010llx-%#010llx] failed\n",
 860		 (unsigned long long) pfn << PAGE_SHIFT,
 861		 (((unsigned long long) pfn + nr_pages) << PAGE_SHIFT) - 1);
 862	memory_notify(MEM_CANCEL_ONLINE, &arg);
 863	remove_pfn_range_from_zone(zone, pfn, nr_pages);
 864	mem_hotplug_done();
 865	return ret;
 866}
 867#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
 868
 869static void reset_node_present_pages(pg_data_t *pgdat)
 870{
 871	struct zone *z;
 872
 873	for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
 874		z->present_pages = 0;
 875
 876	pgdat->node_present_pages = 0;
 877}
 878
 879/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
 880static pg_data_t __ref *hotadd_new_pgdat(int nid)
 881{
 882	struct pglist_data *pgdat;
 883
 
 
 
 
 
 
 884	pgdat = NODE_DATA(nid);
 885	if (!pgdat) {
 886		pgdat = arch_alloc_nodedata(nid);
 887		if (!pgdat)
 888			return NULL;
 889
 890		pgdat->per_cpu_nodestats =
 891			alloc_percpu(struct per_cpu_nodestat);
 892		arch_refresh_nodedata(nid, pgdat);
 893	} else {
 894		int cpu;
 895		/*
 896		 * Reset the nr_zones, order and highest_zoneidx before reuse.
 897		 * Note that kswapd will init kswapd_highest_zoneidx properly
 898		 * when it starts in the near future.
 899		 */
 900		pgdat->nr_zones = 0;
 901		pgdat->kswapd_order = 0;
 902		pgdat->kswapd_highest_zoneidx = 0;
 903		for_each_online_cpu(cpu) {
 904			struct per_cpu_nodestat *p;
 905
 906			p = per_cpu_ptr(pgdat->per_cpu_nodestats, cpu);
 907			memset(p, 0, sizeof(*p));
 908		}
 909	}
 910
 911	/* we can use NODE_DATA(nid) from here */
 912	pgdat->node_id = nid;
 913	pgdat->node_start_pfn = 0;
 914
 915	/* init node's zones as empty zones, we don't have any present pages.*/
 916	free_area_init_core_hotplug(nid);
 917
 918	/*
 919	 * The node we allocated has no zone fallback lists. For avoiding
 920	 * to access not-initialized zonelist, build here.
 921	 */
 922	build_all_zonelists(pgdat);
 923
 924	/*
 925	 * When memory is hot-added, all the memory is in offline state. So
 926	 * clear all zones' present_pages because they will be updated in
 927	 * online_pages() and offline_pages().
 928	 */
 929	reset_node_managed_pages(pgdat);
 930	reset_node_present_pages(pgdat);
 931
 932	return pgdat;
 933}
 934
 935static void rollback_node_hotadd(int nid)
 936{
 937	pg_data_t *pgdat = NODE_DATA(nid);
 938
 939	arch_refresh_nodedata(nid, NULL);
 940	free_percpu(pgdat->per_cpu_nodestats);
 941	arch_free_nodedata(pgdat);
 942}
 943
 944
 945/*
 946 * __try_online_node - online a node if offlined
 947 * @nid: the node ID
 948 * @set_node_online: Whether we want to online the node
 949 * called by cpu_up() to online a node without onlined memory.
 950 *
 951 * Returns:
 952 * 1 -> a new node has been allocated
 953 * 0 -> the node is already online
 954 * -ENOMEM -> the node could not be allocated
 955 */
 956static int __try_online_node(int nid, bool set_node_online)
 957{
 958	pg_data_t *pgdat;
 959	int ret = 1;
 960
 961	if (node_online(nid))
 962		return 0;
 963
 964	pgdat = hotadd_new_pgdat(nid);
 965	if (!pgdat) {
 966		pr_err("Cannot online node %d due to NULL pgdat\n", nid);
 967		ret = -ENOMEM;
 968		goto out;
 969	}
 970
 971	if (set_node_online) {
 972		node_set_online(nid);
 973		ret = register_one_node(nid);
 974		BUG_ON(ret);
 975	}
 976out:
 977	return ret;
 978}
 979
 980/*
 981 * Users of this function always want to online/register the node
 982 */
 983int try_online_node(int nid)
 984{
 985	int ret;
 986
 987	mem_hotplug_begin();
 988	ret =  __try_online_node(nid, true);
 989	mem_hotplug_done();
 990	return ret;
 991}
 992
 993static int check_hotplug_memory_range(u64 start, u64 size)
 994{
 995	/* memory range must be block size aligned */
 996	if (!size || !IS_ALIGNED(start, memory_block_size_bytes()) ||
 997	    !IS_ALIGNED(size, memory_block_size_bytes())) {
 998		pr_err("Block size [%#lx] unaligned hotplug range: start %#llx, size %#llx",
 999		       memory_block_size_bytes(), start, size);
1000		return -EINVAL;
1001	}
1002
1003	return 0;
1004}
1005
1006static int online_memory_block(struct memory_block *mem, void *arg)
1007{
1008	mem->online_type = mhp_default_online_type;
1009	return device_online(&mem->dev);
1010}
1011
1012bool mhp_supports_memmap_on_memory(unsigned long size)
 
 
 
 
 
 
 
 
 
 
 
 
1013{
1014	unsigned long nr_vmemmap_pages = size / PAGE_SIZE;
1015	unsigned long vmemmap_size = nr_vmemmap_pages * sizeof(struct page);
1016	unsigned long remaining_size = size - vmemmap_size;
1017
1018	/*
1019	 * Besides having arch support and the feature enabled at runtime, we
1020	 * need a few more assumptions to hold true:
1021	 *
1022	 * a) We span a single memory block: memory onlining/offlinin;g happens
1023	 *    in memory block granularity. We don't want the vmemmap of online
1024	 *    memory blocks to reside on offline memory blocks. In the future,
1025	 *    we might want to support variable-sized memory blocks to make the
1026	 *    feature more versatile.
1027	 *
1028	 * b) The vmemmap pages span complete PMDs: We don't want vmemmap code
1029	 *    to populate memory from the altmap for unrelated parts (i.e.,
1030	 *    other memory blocks)
1031	 *
1032	 * c) The vmemmap pages (and thereby the pages that will be exposed to
1033	 *    the buddy) have to cover full pageblocks: memory onlining/offlining
1034	 *    code requires applicable ranges to be page-aligned, for example, to
1035	 *    set the migratetypes properly.
1036	 *
1037	 * TODO: Although we have a check here to make sure that vmemmap pages
1038	 *       fully populate a PMD, it is not the right place to check for
1039	 *       this. A much better solution involves improving vmemmap code
1040	 *       to fallback to base pages when trying to populate vmemmap using
1041	 *       altmap as an alternative source of memory, and we do not exactly
1042	 *       populate a single PMD.
1043	 */
1044	return memmap_on_memory &&
1045	       !hugetlb_free_vmemmap_enabled &&
1046	       IS_ENABLED(CONFIG_MHP_MEMMAP_ON_MEMORY) &&
1047	       size == memory_block_size_bytes() &&
1048	       IS_ALIGNED(vmemmap_size, PMD_SIZE) &&
1049	       IS_ALIGNED(remaining_size, (pageblock_nr_pages << PAGE_SHIFT));
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1050}
1051
1052/*
1053 * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
1054 * and online/offline operations (triggered e.g. by sysfs).
1055 *
1056 * we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG
1057 */
1058int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
1059{
1060	struct mhp_params params = { .pgprot = pgprot_mhp(PAGE_KERNEL) };
1061	struct vmem_altmap mhp_altmap = {};
 
1062	u64 start, size;
1063	bool new_node = false;
1064	int ret;
1065
1066	start = res->start;
1067	size = resource_size(res);
1068
1069	ret = check_hotplug_memory_range(start, size);
1070	if (ret)
1071		return ret;
1072
 
 
 
 
 
 
 
1073	if (!node_possible(nid)) {
1074		WARN(1, "node %d was absent from the node_possible_map\n", nid);
1075		return -EINVAL;
1076	}
1077
1078	mem_hotplug_begin();
1079
1080	if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
1081		memblock_add_node(start, size, nid);
 
 
 
 
 
1082
1083	ret = __try_online_node(nid, false);
1084	if (ret < 0)
1085		goto error;
1086	new_node = ret;
1087
1088	/*
1089	 * Self hosted memmap array
1090	 */
1091	if (mhp_flags & MHP_MEMMAP_ON_MEMORY) {
1092		if (!mhp_supports_memmap_on_memory(size)) {
1093			ret = -EINVAL;
 
 
 
 
 
1094			goto error;
1095		}
1096		mhp_altmap.free = PHYS_PFN(size);
1097		mhp_altmap.base_pfn = PHYS_PFN(start);
1098		params.altmap = &mhp_altmap;
1099	}
1100
1101	/* call arch's memory hotadd */
1102	ret = arch_add_memory(nid, start, size, &params);
1103	if (ret < 0)
1104		goto error;
1105
1106	/* create memory block devices after memory was added */
1107	ret = create_memory_block_devices(start, size, mhp_altmap.alloc);
1108	if (ret) {
1109		arch_remove_memory(nid, start, size, NULL);
1110		goto error;
 
1111	}
1112
1113	if (new_node) {
1114		/* If sysfs file of new node can't be created, cpu on the node
1115		 * can't be hot-added. There is no rollback way now.
1116		 * So, check by BUG_ON() to catch it reluctantly..
1117		 * We online node here. We can't roll back from here.
1118		 */
1119		node_set_online(nid);
1120		ret = __register_one_node(nid);
1121		BUG_ON(ret);
1122	}
1123
1124	/* link memory sections under this node.*/
1125	link_mem_sections(nid, PFN_DOWN(start), PFN_UP(start + size - 1),
1126			  MEMINIT_HOTPLUG);
1127
1128	/* create new memmap entry */
1129	if (!strcmp(res->name, "System RAM"))
1130		firmware_map_add_hotplug(start, start + size, "System RAM");
1131
1132	/* device_online() will take the lock when calling online_pages() */
1133	mem_hotplug_done();
1134
1135	/*
1136	 * In case we're allowed to merge the resource, flag it and trigger
1137	 * merging now that adding succeeded.
1138	 */
1139	if (mhp_flags & MHP_MERGE_RESOURCE)
1140		merge_system_ram_resource(res);
1141
1142	/* online pages if requested */
1143	if (mhp_default_online_type != MMOP_OFFLINE)
1144		walk_memory_blocks(start, size, NULL, online_memory_block);
1145
1146	return ret;
1147error:
1148	/* rollback pgdat allocation and others */
1149	if (new_node)
1150		rollback_node_hotadd(nid);
1151	if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
1152		memblock_remove(start, size);
 
1153	mem_hotplug_done();
1154	return ret;
1155}
1156
1157/* requires device_hotplug_lock, see add_memory_resource() */
1158int __ref __add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags)
1159{
1160	struct resource *res;
1161	int ret;
1162
1163	res = register_memory_resource(start, size, "System RAM");
1164	if (IS_ERR(res))
1165		return PTR_ERR(res);
1166
1167	ret = add_memory_resource(nid, res, mhp_flags);
1168	if (ret < 0)
1169		release_memory_resource(res);
1170	return ret;
1171}
1172
1173int add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags)
1174{
1175	int rc;
1176
1177	lock_device_hotplug();
1178	rc = __add_memory(nid, start, size, mhp_flags);
1179	unlock_device_hotplug();
1180
1181	return rc;
1182}
1183EXPORT_SYMBOL_GPL(add_memory);
1184
1185/*
1186 * Add special, driver-managed memory to the system as system RAM. Such
1187 * memory is not exposed via the raw firmware-provided memmap as system
1188 * RAM, instead, it is detected and added by a driver - during cold boot,
1189 * after a reboot, and after kexec.
1190 *
1191 * Reasons why this memory should not be used for the initial memmap of a
1192 * kexec kernel or for placing kexec images:
1193 * - The booting kernel is in charge of determining how this memory will be
1194 *   used (e.g., use persistent memory as system RAM)
1195 * - Coordination with a hypervisor is required before this memory
1196 *   can be used (e.g., inaccessible parts).
1197 *
1198 * For this memory, no entries in /sys/firmware/memmap ("raw firmware-provided
1199 * memory map") are created. Also, the created memory resource is flagged
1200 * with IORESOURCE_SYSRAM_DRIVER_MANAGED, so in-kernel users can special-case
1201 * this memory as well (esp., not place kexec images onto it).
1202 *
1203 * The resource_name (visible via /proc/iomem) has to have the format
1204 * "System RAM ($DRIVER)".
1205 */
1206int add_memory_driver_managed(int nid, u64 start, u64 size,
1207			      const char *resource_name, mhp_t mhp_flags)
1208{
1209	struct resource *res;
1210	int rc;
1211
1212	if (!resource_name ||
1213	    strstr(resource_name, "System RAM (") != resource_name ||
1214	    resource_name[strlen(resource_name) - 1] != ')')
1215		return -EINVAL;
1216
1217	lock_device_hotplug();
1218
1219	res = register_memory_resource(start, size, resource_name);
1220	if (IS_ERR(res)) {
1221		rc = PTR_ERR(res);
1222		goto out_unlock;
1223	}
1224
1225	rc = add_memory_resource(nid, res, mhp_flags);
1226	if (rc < 0)
1227		release_memory_resource(res);
1228
1229out_unlock:
1230	unlock_device_hotplug();
1231	return rc;
1232}
1233EXPORT_SYMBOL_GPL(add_memory_driver_managed);
1234
1235/*
1236 * Platforms should define arch_get_mappable_range() that provides
1237 * maximum possible addressable physical memory range for which the
1238 * linear mapping could be created. The platform returned address
1239 * range must adhere to these following semantics.
1240 *
1241 * - range.start <= range.end
1242 * - Range includes both end points [range.start..range.end]
1243 *
1244 * There is also a fallback definition provided here, allowing the
1245 * entire possible physical address range in case any platform does
1246 * not define arch_get_mappable_range().
1247 */
1248struct range __weak arch_get_mappable_range(void)
1249{
1250	struct range mhp_range = {
1251		.start = 0UL,
1252		.end = -1ULL,
1253	};
1254	return mhp_range;
1255}
1256
1257struct range mhp_get_pluggable_range(bool need_mapping)
1258{
1259	const u64 max_phys = (1ULL << MAX_PHYSMEM_BITS) - 1;
1260	struct range mhp_range;
1261
1262	if (need_mapping) {
1263		mhp_range = arch_get_mappable_range();
1264		if (mhp_range.start > max_phys) {
1265			mhp_range.start = 0;
1266			mhp_range.end = 0;
1267		}
1268		mhp_range.end = min_t(u64, mhp_range.end, max_phys);
1269	} else {
1270		mhp_range.start = 0;
1271		mhp_range.end = max_phys;
1272	}
1273	return mhp_range;
1274}
1275EXPORT_SYMBOL_GPL(mhp_get_pluggable_range);
1276
1277bool mhp_range_allowed(u64 start, u64 size, bool need_mapping)
1278{
1279	struct range mhp_range = mhp_get_pluggable_range(need_mapping);
1280	u64 end = start + size;
1281
1282	if (start < end && start >= mhp_range.start && (end - 1) <= mhp_range.end)
1283		return true;
1284
1285	pr_warn("Hotplug memory [%#llx-%#llx] exceeds maximum addressable range [%#llx-%#llx]\n",
1286		start, end, mhp_range.start, mhp_range.end);
1287	return false;
1288}
1289
1290#ifdef CONFIG_MEMORY_HOTREMOVE
1291/*
1292 * Confirm all pages in a range [start, end) belong to the same zone (skipping
1293 * memory holes). When true, return the zone.
1294 */
1295struct zone *test_pages_in_a_zone(unsigned long start_pfn,
1296				  unsigned long end_pfn)
1297{
1298	unsigned long pfn, sec_end_pfn;
1299	struct zone *zone = NULL;
1300	struct page *page;
1301	int i;
1302	for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn + 1);
1303	     pfn < end_pfn;
1304	     pfn = sec_end_pfn, sec_end_pfn += PAGES_PER_SECTION) {
1305		/* Make sure the memory section is present first */
1306		if (!present_section_nr(pfn_to_section_nr(pfn)))
1307			continue;
1308		for (; pfn < sec_end_pfn && pfn < end_pfn;
1309		     pfn += MAX_ORDER_NR_PAGES) {
1310			i = 0;
1311			/* This is just a CONFIG_HOLES_IN_ZONE check.*/
1312			while ((i < MAX_ORDER_NR_PAGES) &&
1313				!pfn_valid_within(pfn + i))
1314				i++;
1315			if (i == MAX_ORDER_NR_PAGES || pfn + i >= end_pfn)
1316				continue;
1317			/* Check if we got outside of the zone */
1318			if (zone && !zone_spans_pfn(zone, pfn + i))
1319				return NULL;
1320			page = pfn_to_page(pfn + i);
1321			if (zone && page_zone(page) != zone)
1322				return NULL;
1323			zone = page_zone(page);
1324		}
1325	}
1326
1327	return zone;
1328}
1329
1330/*
1331 * Scan pfn range [start,end) to find movable/migratable pages (LRU pages,
1332 * non-lru movable pages and hugepages). Will skip over most unmovable
1333 * pages (esp., pages that can be skipped when offlining), but bail out on
1334 * definitely unmovable pages.
1335 *
1336 * Returns:
1337 *	0 in case a movable page is found and movable_pfn was updated.
1338 *	-ENOENT in case no movable page was found.
1339 *	-EBUSY in case a definitely unmovable page was found.
1340 */
1341static int scan_movable_pages(unsigned long start, unsigned long end,
1342			      unsigned long *movable_pfn)
1343{
1344	unsigned long pfn;
1345
1346	for (pfn = start; pfn < end; pfn++) {
1347		struct page *page, *head;
1348		unsigned long skip;
1349
1350		if (!pfn_valid(pfn))
1351			continue;
1352		page = pfn_to_page(pfn);
1353		if (PageLRU(page))
1354			goto found;
1355		if (__PageMovable(page))
1356			goto found;
1357
1358		/*
1359		 * PageOffline() pages that are not marked __PageMovable() and
1360		 * have a reference count > 0 (after MEM_GOING_OFFLINE) are
1361		 * definitely unmovable. If their reference count would be 0,
1362		 * they could at least be skipped when offlining memory.
1363		 */
1364		if (PageOffline(page) && page_count(page))
1365			return -EBUSY;
1366
1367		if (!PageHuge(page))
1368			continue;
1369		head = compound_head(page);
1370		/*
1371		 * This test is racy as we hold no reference or lock.  The
1372		 * hugetlb page could have been free'ed and head is no longer
1373		 * a hugetlb page before the following check.  In such unlikely
1374		 * cases false positives and negatives are possible.  Calling
1375		 * code must deal with these scenarios.
1376		 */
1377		if (HPageMigratable(head))
1378			goto found;
1379		skip = compound_nr(head) - (page - head);
1380		pfn += skip - 1;
1381	}
1382	return -ENOENT;
1383found:
1384	*movable_pfn = pfn;
1385	return 0;
1386}
1387
1388static int
1389do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
1390{
1391	unsigned long pfn;
1392	struct page *page, *head;
1393	int ret = 0;
1394	LIST_HEAD(source);
1395	static DEFINE_RATELIMIT_STATE(migrate_rs, DEFAULT_RATELIMIT_INTERVAL,
1396				      DEFAULT_RATELIMIT_BURST);
1397
1398	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
 
 
 
1399		if (!pfn_valid(pfn))
1400			continue;
1401		page = pfn_to_page(pfn);
1402		head = compound_head(page);
 
1403
1404		if (PageHuge(page)) {
1405			pfn = page_to_pfn(head) + compound_nr(head) - 1;
1406			isolate_huge_page(head, &source);
1407			continue;
1408		} else if (PageTransHuge(page))
1409			pfn = page_to_pfn(head) + thp_nr_pages(page) - 1;
1410
1411		/*
1412		 * HWPoison pages have elevated reference counts so the migration would
1413		 * fail on them. It also doesn't make any sense to migrate them in the
1414		 * first place. Still try to unmap such a page in case it is still mapped
1415		 * (e.g. current hwpoison implementation doesn't unmap KSM pages but keep
1416		 * the unmap as the catch all safety net).
1417		 */
1418		if (PageHWPoison(page)) {
1419			if (WARN_ON(PageLRU(page)))
1420				isolate_lru_page(page);
1421			if (page_mapped(page))
1422				try_to_unmap(page, TTU_IGNORE_MLOCK);
1423			continue;
1424		}
1425
1426		if (!get_page_unless_zero(page))
1427			continue;
1428		/*
1429		 * We can skip free pages. And we can deal with pages on
1430		 * LRU and non-lru movable pages.
1431		 */
1432		if (PageLRU(page))
1433			ret = isolate_lru_page(page);
1434		else
1435			ret = isolate_movable_page(page, ISOLATE_UNEVICTABLE);
1436		if (!ret) { /* Success */
1437			list_add_tail(&page->lru, &source);
1438			if (!__PageMovable(page))
1439				inc_node_page_state(page, NR_ISOLATED_ANON +
1440						    page_is_file_lru(page));
1441
1442		} else {
1443			if (__ratelimit(&migrate_rs)) {
1444				pr_warn("failed to isolate pfn %lx\n", pfn);
1445				dump_page(page, "isolation failed");
1446			}
1447		}
1448		put_page(page);
1449	}
1450	if (!list_empty(&source)) {
1451		nodemask_t nmask = node_states[N_MEMORY];
1452		struct migration_target_control mtc = {
1453			.nmask = &nmask,
1454			.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
1455		};
 
1456
1457		/*
1458		 * We have checked that migration range is on a single zone so
1459		 * we can use the nid of the first page to all the others.
1460		 */
1461		mtc.nid = page_to_nid(list_first_entry(&source, struct page, lru));
1462
1463		/*
1464		 * try to allocate from a different node but reuse this node
1465		 * if there are no other online nodes to be used (e.g. we are
1466		 * offlining a part of the only existing node)
1467		 */
1468		node_clear(mtc.nid, nmask);
1469		if (nodes_empty(nmask))
1470			node_set(mtc.nid, nmask);
1471		ret = migrate_pages(&source, alloc_migration_target, NULL,
1472			(unsigned long)&mtc, MIGRATE_SYNC, MR_MEMORY_HOTPLUG);
1473		if (ret) {
1474			list_for_each_entry(page, &source, lru) {
1475				if (__ratelimit(&migrate_rs)) {
1476					pr_warn("migrating pfn %lx failed ret:%d\n",
1477						page_to_pfn(page), ret);
1478					dump_page(page, "migration failure");
1479				}
1480			}
1481			putback_movable_pages(&source);
1482		}
1483	}
1484
1485	return ret;
1486}
1487
1488static int __init cmdline_parse_movable_node(char *p)
1489{
1490	movable_node_enabled = true;
1491	return 0;
1492}
1493early_param("movable_node", cmdline_parse_movable_node);
1494
1495/* check which state of node_states will be changed when offline memory */
1496static void node_states_check_changes_offline(unsigned long nr_pages,
1497		struct zone *zone, struct memory_notify *arg)
1498{
1499	struct pglist_data *pgdat = zone->zone_pgdat;
1500	unsigned long present_pages = 0;
1501	enum zone_type zt;
1502
1503	arg->status_change_nid = NUMA_NO_NODE;
1504	arg->status_change_nid_normal = NUMA_NO_NODE;
1505	arg->status_change_nid_high = NUMA_NO_NODE;
1506
1507	/*
1508	 * Check whether node_states[N_NORMAL_MEMORY] will be changed.
1509	 * If the memory to be offline is within the range
1510	 * [0..ZONE_NORMAL], and it is the last present memory there,
1511	 * the zones in that range will become empty after the offlining,
1512	 * thus we can determine that we need to clear the node from
1513	 * node_states[N_NORMAL_MEMORY].
1514	 */
1515	for (zt = 0; zt <= ZONE_NORMAL; zt++)
1516		present_pages += pgdat->node_zones[zt].present_pages;
1517	if (zone_idx(zone) <= ZONE_NORMAL && nr_pages >= present_pages)
1518		arg->status_change_nid_normal = zone_to_nid(zone);
1519
1520#ifdef CONFIG_HIGHMEM
1521	/*
1522	 * node_states[N_HIGH_MEMORY] contains nodes which
1523	 * have normal memory or high memory.
1524	 * Here we add the present_pages belonging to ZONE_HIGHMEM.
1525	 * If the zone is within the range of [0..ZONE_HIGHMEM), and
1526	 * we determine that the zones in that range become empty,
1527	 * we need to clear the node for N_HIGH_MEMORY.
1528	 */
1529	present_pages += pgdat->node_zones[ZONE_HIGHMEM].present_pages;
1530	if (zone_idx(zone) <= ZONE_HIGHMEM && nr_pages >= present_pages)
1531		arg->status_change_nid_high = zone_to_nid(zone);
1532#endif
1533
1534	/*
1535	 * We have accounted the pages from [0..ZONE_NORMAL), and
1536	 * in case of CONFIG_HIGHMEM the pages from ZONE_HIGHMEM
1537	 * as well.
1538	 * Here we count the possible pages from ZONE_MOVABLE.
1539	 * If after having accounted all the pages, we see that the nr_pages
1540	 * to be offlined is over or equal to the accounted pages,
1541	 * we know that the node will become empty, and so, we can clear
1542	 * it for N_MEMORY as well.
1543	 */
1544	present_pages += pgdat->node_zones[ZONE_MOVABLE].present_pages;
1545
1546	if (nr_pages >= present_pages)
1547		arg->status_change_nid = zone_to_nid(zone);
1548}
1549
1550static void node_states_clear_node(int node, struct memory_notify *arg)
1551{
1552	if (arg->status_change_nid_normal >= 0)
1553		node_clear_state(node, N_NORMAL_MEMORY);
1554
1555	if (arg->status_change_nid_high >= 0)
1556		node_clear_state(node, N_HIGH_MEMORY);
1557
1558	if (arg->status_change_nid >= 0)
1559		node_clear_state(node, N_MEMORY);
1560}
1561
1562static int count_system_ram_pages_cb(unsigned long start_pfn,
1563				     unsigned long nr_pages, void *data)
1564{
1565	unsigned long *nr_system_ram_pages = data;
1566
1567	*nr_system_ram_pages += nr_pages;
1568	return 0;
1569}
1570
1571int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 
 
 
 
1572{
1573	const unsigned long end_pfn = start_pfn + nr_pages;
1574	unsigned long pfn, system_ram_pages = 0;
 
1575	unsigned long flags;
1576	struct zone *zone;
1577	struct memory_notify arg;
1578	int ret, node;
1579	char *reason;
 
1580
1581	/*
1582	 * {on,off}lining is constrained to full memory sections (or more
1583	 * precisely to memory blocks from the user space POV).
1584	 * memmap_on_memory is an exception because it reserves initial part
1585	 * of the physical memory space for vmemmaps. That space is pageblock
1586	 * aligned.
1587	 */
1588	if (WARN_ON_ONCE(!nr_pages ||
1589			 !IS_ALIGNED(start_pfn, pageblock_nr_pages) ||
1590			 !IS_ALIGNED(start_pfn + nr_pages, PAGES_PER_SECTION)))
1591		return -EINVAL;
1592
1593	mem_hotplug_begin();
1594
1595	/*
1596	 * Don't allow to offline memory blocks that contain holes.
1597	 * Consequently, memory blocks with holes can never get onlined
1598	 * via the hotplug path - online_pages() - as hotplugged memory has
1599	 * no holes. This way, we e.g., don't have to worry about marking
1600	 * memory holes PG_reserved, don't need pfn_valid() checks, and can
1601	 * avoid using walk_system_ram_range() later.
1602	 */
1603	walk_system_ram_range(start_pfn, nr_pages, &system_ram_pages,
1604			      count_system_ram_pages_cb);
1605	if (system_ram_pages != nr_pages) {
1606		ret = -EINVAL;
1607		reason = "memory holes";
1608		goto failed_removal;
1609	}
1610
1611	/* This makes hotplug much easier...and readable.
1612	   we assume this for now. .*/
1613	zone = test_pages_in_a_zone(start_pfn, end_pfn);
1614	if (!zone) {
 
 
 
1615		ret = -EINVAL;
1616		reason = "multizone range";
1617		goto failed_removal;
1618	}
1619	node = zone_to_nid(zone);
1620
1621	/*
1622	 * Disable pcplists so that page isolation cannot race with freeing
1623	 * in a way that pages from isolated pageblock are left on pcplists.
1624	 */
1625	zone_pcp_disable(zone);
1626	lru_cache_disable();
1627
1628	/* set above range as isolated */
1629	ret = start_isolate_page_range(start_pfn, end_pfn,
1630				       MIGRATE_MOVABLE,
1631				       MEMORY_OFFLINE | REPORT_FAILURE);
 
1632	if (ret) {
1633		reason = "failure to isolate range";
1634		goto failed_removal_pcplists_disabled;
1635	}
1636
1637	arg.start_pfn = start_pfn;
1638	arg.nr_pages = nr_pages;
1639	node_states_check_changes_offline(nr_pages, zone, &arg);
1640
1641	ret = memory_notify(MEM_GOING_OFFLINE, &arg);
1642	ret = notifier_to_errno(ret);
1643	if (ret) {
1644		reason = "notifier failure";
1645		goto failed_removal_isolated;
1646	}
1647
1648	do {
1649		pfn = start_pfn;
1650		do {
 
 
 
 
 
1651			if (signal_pending(current)) {
1652				ret = -EINTR;
1653				reason = "signal backoff";
1654				goto failed_removal_isolated;
1655			}
1656
1657			cond_resched();
1658
1659			ret = scan_movable_pages(pfn, end_pfn, &pfn);
1660			if (!ret) {
1661				/*
1662				 * TODO: fatal migration failures should bail
1663				 * out
1664				 */
1665				do_migrate_range(pfn, end_pfn);
1666			}
1667		} while (!ret);
1668
1669		if (ret != -ENOENT) {
1670			reason = "unmovable page";
1671			goto failed_removal_isolated;
1672		}
1673
1674		/*
1675		 * Dissolve free hugepages in the memory block before doing
1676		 * offlining actually in order to make hugetlbfs's object
1677		 * counting consistent.
1678		 */
1679		ret = dissolve_free_huge_pages(start_pfn, end_pfn);
1680		if (ret) {
1681			reason = "failure to dissolve huge pages";
1682			goto failed_removal_isolated;
1683		}
1684
1685		ret = test_pages_isolated(start_pfn, end_pfn, MEMORY_OFFLINE);
1686
1687	} while (ret);
1688
1689	/* Mark all sections offline and remove free pages from the buddy. */
1690	__offline_isolated_pages(start_pfn, end_pfn);
1691	pr_debug("Offlined Pages %ld\n", nr_pages);
1692
1693	/*
1694	 * The memory sections are marked offline, and the pageblock flags
1695	 * effectively stale; nobody should be touching them. Fixup the number
1696	 * of isolated pageblocks, memory onlining will properly revert this.
1697	 */
1698	spin_lock_irqsave(&zone->lock, flags);
1699	zone->nr_isolate_pageblock -= nr_pages / pageblock_nr_pages;
1700	spin_unlock_irqrestore(&zone->lock, flags);
1701
1702	lru_cache_enable();
1703	zone_pcp_enable(zone);
1704
1705	/* removal success */
1706	adjust_managed_page_count(pfn_to_page(start_pfn), -nr_pages);
1707	adjust_present_page_count(zone, -nr_pages);
1708
1709	/* reinitialise watermarks and update pcp limits */
1710	init_per_zone_wmark_min();
1711
 
 
 
 
 
1712	if (!populated_zone(zone)) {
1713		zone_pcp_reset(zone);
1714		build_all_zonelists(NULL);
1715	}
1716
1717	node_states_clear_node(node, &arg);
1718	if (arg.status_change_nid >= 0) {
1719		kswapd_stop(node);
1720		kcompactd_stop(node);
 
1721	}
1722
1723	writeback_set_ratelimit();
1724
1725	memory_notify(MEM_OFFLINE, &arg);
1726	remove_pfn_range_from_zone(zone, start_pfn, nr_pages);
1727	mem_hotplug_done();
1728	return 0;
1729
1730failed_removal_isolated:
 
1731	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
1732	memory_notify(MEM_CANCEL_OFFLINE, &arg);
1733failed_removal_pcplists_disabled:
1734	lru_cache_enable();
1735	zone_pcp_enable(zone);
1736failed_removal:
1737	pr_debug("memory offlining [mem %#010llx-%#010llx] failed due to %s\n",
1738		 (unsigned long long) start_pfn << PAGE_SHIFT,
1739		 ((unsigned long long) end_pfn << PAGE_SHIFT) - 1,
1740		 reason);
1741	/* pushback to free area */
1742	mem_hotplug_done();
1743	return ret;
1744}
1745
1746static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)
1747{
1748	int ret = !is_memblock_offlined(mem);
1749
1750	if (unlikely(ret)) {
 
1751		phys_addr_t beginpa, endpa;
1752
1753		beginpa = PFN_PHYS(section_nr_to_pfn(mem->start_section_nr));
1754		endpa = beginpa + memory_block_size_bytes() - 1;
1755		pr_warn("removing memory fails, because memory [%pa-%pa] is onlined\n",
1756			&beginpa, &endpa);
1757
1758		return -EBUSY;
1759	}
1760	return 0;
1761}
1762
1763static int get_nr_vmemmap_pages_cb(struct memory_block *mem, void *arg)
1764{
1765	/*
1766	 * If not set, continue with the next block.
1767	 */
1768	return mem->nr_vmemmap_pages;
 
 
1769}
1770
1771static int check_cpu_on_node(pg_data_t *pgdat)
1772{
1773	int cpu;
1774
1775	for_each_present_cpu(cpu) {
1776		if (cpu_to_node(cpu) == pgdat->node_id)
1777			/*
1778			 * the cpu on this node isn't removed, and we can't
1779			 * offline this node.
1780			 */
1781			return -EBUSY;
1782	}
1783
1784	return 0;
1785}
1786
1787static int check_no_memblock_for_node_cb(struct memory_block *mem, void *arg)
1788{
1789	int nid = *(int *)arg;
1790
1791	/*
1792	 * If a memory block belongs to multiple nodes, the stored nid is not
1793	 * reliable. However, such blocks are always online (e.g., cannot get
1794	 * offlined) and, therefore, are still spanned by the node.
1795	 */
1796	return mem->nid == nid ? -EEXIST : 0;
1797}
1798
1799/**
1800 * try_offline_node
1801 * @nid: the node ID
1802 *
1803 * Offline a node if all memory sections and cpus of the node are removed.
1804 *
1805 * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
1806 * and online/offline operations before this call.
1807 */
1808void try_offline_node(int nid)
1809{
1810	pg_data_t *pgdat = NODE_DATA(nid);
1811	int rc;
1812
1813	/*
1814	 * If the node still spans pages (especially ZONE_DEVICE), don't
1815	 * offline it. A node spans memory after move_pfn_range_to_zone(),
1816	 * e.g., after the memory block was onlined.
1817	 */
1818	if (pgdat->node_spanned_pages)
1819		return;
1820
1821	/*
1822	 * Especially offline memory blocks might not be spanned by the
1823	 * node. They will get spanned by the node once they get onlined.
1824	 * However, they link to the node in sysfs and can get onlined later.
1825	 */
1826	rc = for_each_memory_block(&nid, check_no_memblock_for_node_cb);
1827	if (rc)
1828		return;
1829
1830	if (check_cpu_on_node(pgdat))
1831		return;
1832
1833	/*
1834	 * all memory/cpu of this node are removed, we can offline this
1835	 * node now.
1836	 */
1837	node_set_offline(nid);
1838	unregister_one_node(nid);
1839}
1840EXPORT_SYMBOL(try_offline_node);
1841
1842static int __ref try_remove_memory(int nid, u64 start, u64 size)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1843{
1844	int rc = 0;
1845	struct vmem_altmap mhp_altmap = {};
1846	struct vmem_altmap *altmap = NULL;
1847	unsigned long nr_vmemmap_pages;
1848
1849	BUG_ON(check_hotplug_memory_range(start, size));
1850
1851	/*
1852	 * All memory blocks must be offlined before removing memory.  Check
1853	 * whether all memory blocks in question are offline and return error
1854	 * if this is not the case.
 
 
 
 
1855	 */
1856	rc = walk_memory_blocks(start, size, NULL, check_memblock_offlined_cb);
1857	if (rc)
1858		return rc;
1859
1860	/*
1861	 * We only support removing memory added with MHP_MEMMAP_ON_MEMORY in
1862	 * the same granularity it was added - a single memory block.
1863	 */
1864	if (memmap_on_memory) {
1865		nr_vmemmap_pages = walk_memory_blocks(start, size, NULL,
1866						      get_nr_vmemmap_pages_cb);
1867		if (nr_vmemmap_pages) {
1868			if (size != memory_block_size_bytes()) {
1869				pr_warn("Refuse to remove %#llx - %#llx,"
1870					"wrong granularity\n",
1871					start, start + size);
1872				return -EINVAL;
1873			}
1874
1875			/*
1876			 * Let remove_pmd_table->free_hugepage_table do the
1877			 * right thing if we used vmem_altmap when hot-adding
1878			 * the range.
1879			 */
1880			mhp_altmap.alloc = nr_vmemmap_pages;
1881			altmap = &mhp_altmap;
1882		}
1883	}
1884
1885	/* remove memmap entry */
1886	firmware_map_remove(start, start + size, "System RAM");
1887
1888	/*
1889	 * Memory block device removal under the device_hotplug_lock is
1890	 * a barrier against racing online attempts.
1891	 */
1892	remove_memory_block_devices(start, size);
1893
1894	mem_hotplug_begin();
1895
1896	arch_remove_memory(nid, start, size, altmap);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1897
1898	if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {
1899		memblock_free(start, size);
1900		memblock_remove(start, size);
1901	}
1902
1903	release_mem_region_adjustable(start, size);
1904
1905	try_offline_node(nid);
 
1906
1907	mem_hotplug_done();
1908	return 0;
1909}
1910
1911/**
1912 * __remove_memory - Remove memory if every memory block is offline
1913 * @nid: the node ID
1914 * @start: physical address of the region to remove
1915 * @size: size of the region to remove
1916 *
1917 * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
1918 * and online/offline operations before this call, as required by
1919 * try_offline_node().
1920 */
1921void __remove_memory(int nid, u64 start, u64 size)
1922{
1923
1924	/*
1925	 * trigger BUG() if some memory is not offlined prior to calling this
1926	 * function
1927	 */
1928	if (try_remove_memory(nid, start, size))
1929		BUG();
1930}
1931
1932/*
1933 * Remove memory if every memory block is offline, otherwise return -EBUSY is
1934 * some memory is not offline
1935 */
1936int remove_memory(int nid, u64 start, u64 size)
1937{
1938	int rc;
1939
1940	lock_device_hotplug();
1941	rc  = try_remove_memory(nid, start, size);
1942	unlock_device_hotplug();
1943
1944	return rc;
1945}
1946EXPORT_SYMBOL_GPL(remove_memory);
1947
1948static int try_offline_memory_block(struct memory_block *mem, void *arg)
1949{
1950	uint8_t online_type = MMOP_ONLINE_KERNEL;
1951	uint8_t **online_types = arg;
1952	struct page *page;
1953	int rc;
1954
1955	/*
1956	 * Sense the online_type via the zone of the memory block. Offlining
1957	 * with multiple zones within one memory block will be rejected
1958	 * by offlining code ... so we don't care about that.
1959	 */
1960	page = pfn_to_online_page(section_nr_to_pfn(mem->start_section_nr));
1961	if (page && zone_idx(page_zone(page)) == ZONE_MOVABLE)
1962		online_type = MMOP_ONLINE_MOVABLE;
1963
1964	rc = device_offline(&mem->dev);
1965	/*
1966	 * Default is MMOP_OFFLINE - change it only if offlining succeeded,
1967	 * so try_reonline_memory_block() can do the right thing.
1968	 */
1969	if (!rc)
1970		**online_types = online_type;
1971
1972	(*online_types)++;
1973	/* Ignore if already offline. */
1974	return rc < 0 ? rc : 0;
1975}
1976
1977static int try_reonline_memory_block(struct memory_block *mem, void *arg)
1978{
1979	uint8_t **online_types = arg;
1980	int rc;
1981
1982	if (**online_types != MMOP_OFFLINE) {
1983		mem->online_type = **online_types;
1984		rc = device_online(&mem->dev);
1985		if (rc < 0)
1986			pr_warn("%s: Failed to re-online memory: %d",
1987				__func__, rc);
1988	}
1989
1990	/* Continue processing all remaining memory blocks. */
1991	(*online_types)++;
1992	return 0;
1993}
1994
1995/*
1996 * Try to offline and remove memory. Might take a long time to finish in case
1997 * memory is still in use. Primarily useful for memory devices that logically
1998 * unplugged all memory (so it's no longer in use) and want to offline + remove
1999 * that memory.
2000 */
2001int offline_and_remove_memory(int nid, u64 start, u64 size)
2002{
2003	const unsigned long mb_count = size / memory_block_size_bytes();
2004	uint8_t *online_types, *tmp;
2005	int rc;
2006
2007	if (!IS_ALIGNED(start, memory_block_size_bytes()) ||
2008	    !IS_ALIGNED(size, memory_block_size_bytes()) || !size)
2009		return -EINVAL;
2010
2011	/*
2012	 * We'll remember the old online type of each memory block, so we can
2013	 * try to revert whatever we did when offlining one memory block fails
2014	 * after offlining some others succeeded.
2015	 */
2016	online_types = kmalloc_array(mb_count, sizeof(*online_types),
2017				     GFP_KERNEL);
2018	if (!online_types)
2019		return -ENOMEM;
2020	/*
2021	 * Initialize all states to MMOP_OFFLINE, so when we abort processing in
2022	 * try_offline_memory_block(), we'll skip all unprocessed blocks in
2023	 * try_reonline_memory_block().
2024	 */
2025	memset(online_types, MMOP_OFFLINE, mb_count);
2026
2027	lock_device_hotplug();
2028
2029	tmp = online_types;
2030	rc = walk_memory_blocks(start, size, &tmp, try_offline_memory_block);
2031
2032	/*
2033	 * In case we succeeded to offline all memory, remove it.
2034	 * This cannot fail as it cannot get onlined in the meantime.
2035	 */
2036	if (!rc) {
2037		rc = try_remove_memory(nid, start, size);
2038		if (rc)
2039			pr_err("%s: Failed to remove memory: %d", __func__, rc);
2040	}
2041
2042	/*
2043	 * Rollback what we did. While memory onlining might theoretically fail
2044	 * (nacked by a notifier), it barely ever happens.
2045	 */
2046	if (rc) {
2047		tmp = online_types;
2048		walk_memory_blocks(start, size, &tmp,
2049				   try_reonline_memory_block);
2050	}
2051	unlock_device_hotplug();
2052
2053	kfree(online_types);
2054	return rc;
2055}
2056EXPORT_SYMBOL_GPL(offline_and_remove_memory);
2057#endif /* CONFIG_MEMORY_HOTREMOVE */