sparse.c 20.3 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791
/*
 * sparse memory mappings.
 */
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/mmzone.h>
#include <linux/bootmem.h>
#include <linux/highmem.h>
#include <linux/export.h>
#include <linux/spinlock.h>
#include <linux/vmalloc.h>
#include "internal.h"
#include <asm/dma.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>

/*
 * Permanent SPARSEMEM data:
 *
 * 1) mem_section	- memory sections, mem_map's for valid memory
 */
#ifdef CONFIG_SPARSEMEM_EXTREME
struct mem_section *mem_section[NR_SECTION_ROOTS]
	____cacheline_internodealigned_in_smp;
#else
struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
	____cacheline_internodealigned_in_smp;
#endif
EXPORT_SYMBOL(mem_section);

#ifdef NODE_NOT_IN_PAGE_FLAGS
/*
 * If we did not store the node number in the page then we have to
 * do a lookup in the section_to_node_table in order to find which
 * node the page belongs to.
 */
#if MAX_NUMNODES <= 256
static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
#else
static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
#endif

int page_to_nid(const struct page *page)
{
	return section_to_node_table[page_to_section(page)];
}
EXPORT_SYMBOL(page_to_nid);

static void set_section_nid(unsigned long section_nr, int nid)
{
	section_to_node_table[section_nr] = nid;
}
#else /* !NODE_NOT_IN_PAGE_FLAGS */
static inline void set_section_nid(unsigned long section_nr, int nid)
{
}
#endif

#ifdef CONFIG_SPARSEMEM_EXTREME
static struct mem_section noinline __init_refok *sparse_index_alloc(int nid)
{
	struct mem_section *section = NULL;
	unsigned long array_size = SECTIONS_PER_ROOT *
				   sizeof(struct mem_section);

	if (slab_is_available()) {
		if (node_state(nid, N_HIGH_MEMORY))
			section = kzalloc_node(array_size, GFP_KERNEL, nid);
		else
			section = kzalloc(array_size, GFP_KERNEL);
	} else {
		section = alloc_bootmem_node(NODE_DATA(nid), array_size);
	}

	return section;
}

static int __meminit sparse_index_init(unsigned long section_nr, int nid)
{
	unsigned long root = SECTION_NR_TO_ROOT(section_nr);
	struct mem_section *section;
	int ret = 0;

	if (mem_section[root])
		return -EEXIST;

	section = sparse_index_alloc(nid);
	if (!section)
		return -ENOMEM;

	mem_section[root] = section;

	return ret;
}
#else /* !SPARSEMEM_EXTREME */
static inline int sparse_index_init(unsigned long section_nr, int nid)
{
	return 0;
}
#endif

/*
 * Although written for the SPARSEMEM_EXTREME case, this happens
 * to also work for the flat array case because
 * NR_SECTION_ROOTS==NR_MEM_SECTIONS.
 */
int __section_nr(struct mem_section* ms)
{
	unsigned long root_nr;
	struct mem_section* root;

	for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
		root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
		if (!root)
			continue;

		if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
		     break;
	}

	VM_BUG_ON(root_nr == NR_SECTION_ROOTS);

	return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
}

/*
 * During early boot, before section_mem_map is used for an actual
 * mem_map, we use section_mem_map to store the section's NUMA
 * node.  This keeps us from having to use another data structure.  The
 * node information is cleared just before we store the real mem_map.
 */
static inline unsigned long sparse_encode_early_nid(int nid)
{
	return (nid << SECTION_NID_SHIFT);
}

static inline int sparse_early_nid(struct mem_section *section)
{
	return (section->section_mem_map >> SECTION_NID_SHIFT);
}

/* Validate the physical addressing limitations of the model */
void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
						unsigned long *end_pfn)
{
	unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);

	/*
	 * Sanity checks - do not allow an architecture to pass
	 * in larger pfns than the maximum scope of sparsemem:
	 */
	if (*start_pfn > max_sparsemem_pfn) {
		mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
			"Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
			*start_pfn, *end_pfn, max_sparsemem_pfn);
		WARN_ON_ONCE(1);
		*start_pfn = max_sparsemem_pfn;
		*end_pfn = max_sparsemem_pfn;
	} else if (*end_pfn > max_sparsemem_pfn) {
		mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
			"End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
			*start_pfn, *end_pfn, max_sparsemem_pfn);
		WARN_ON_ONCE(1);
		*end_pfn = max_sparsemem_pfn;
	}
}

/* Record a memory area against a node. */
void __init memory_present(int nid, unsigned long start, unsigned long end)
{
	unsigned long pfn;

	start &= PAGE_SECTION_MASK;
	mminit_validate_memmodel_limits(&start, &end);
	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
		unsigned long section = pfn_to_section_nr(pfn);
		struct mem_section *ms;

		sparse_index_init(section, nid);
		set_section_nid(section, nid);

		ms = __nr_to_section(section);
		if (!ms->section_mem_map)
			ms->section_mem_map = sparse_encode_early_nid(nid) |
							SECTION_MARKED_PRESENT;
	}
}

/*
 * Only used by the i386 NUMA architecures, but relatively
 * generic code.
 */
unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
						     unsigned long end_pfn)
{
	unsigned long pfn;
	unsigned long nr_pages = 0;

	mminit_validate_memmodel_limits(&start_pfn, &end_pfn);
	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
		if (nid != early_pfn_to_nid(pfn))
			continue;

		if (pfn_present(pfn))
			nr_pages += PAGES_PER_SECTION;
	}

	return nr_pages * sizeof(struct page);
}

/*
 * Subtle, we encode the real pfn into the mem_map such that
 * the identity pfn - section_mem_map will return the actual
 * physical page frame number.
 */
static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
{
	return (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
}

/*
 * Decode mem_map from the coded memmap
 */
struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
{
	/* mask off the extra low bits of information */
	coded_mem_map &= SECTION_MAP_MASK;
	return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
}

static int __meminit sparse_init_one_section(struct mem_section *ms,
		unsigned long pnum, struct page *mem_map,
		unsigned long *pageblock_bitmap)
{
	if (!present_section(ms))
		return -EINVAL;

	ms->section_mem_map &= ~SECTION_MAP_MASK;
	ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
							SECTION_HAS_MEM_MAP;
 	ms->pageblock_flags = pageblock_bitmap;

	return 1;
}

unsigned long usemap_size(void)
{
	unsigned long size_bytes;
	size_bytes = roundup(SECTION_BLOCKFLAGS_BITS, 8) / 8;
	size_bytes = roundup(size_bytes, sizeof(unsigned long));
	return size_bytes;
}

#ifdef CONFIG_MEMORY_HOTPLUG
static unsigned long *__kmalloc_section_usemap(void)
{
	return kmalloc(usemap_size(), GFP_KERNEL);
}
#endif /* CONFIG_MEMORY_HOTPLUG */

#ifdef CONFIG_MEMORY_HOTREMOVE
static unsigned long * __init
sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
					 unsigned long size)
{
	unsigned long goal, limit;
	unsigned long *p;
	int nid;
	/*
	 * A page may contain usemaps for other sections preventing the
	 * page being freed and making a section unremovable while
	 * other sections referencing the usemap retmain active. Similarly,
	 * a pgdat can prevent a section being removed. If section A
	 * contains a pgdat and section B contains the usemap, both
	 * sections become inter-dependent. This allocates usemaps
	 * from the same section as the pgdat where possible to avoid
	 * this problem.
	 */
	goal = __pa(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
	limit = goal + (1UL << PA_SECTION_SHIFT);
	nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
again:
	p = ___alloc_bootmem_node_nopanic(NODE_DATA(nid), size,
					  SMP_CACHE_BYTES, goal, limit);
	if (!p && limit) {
		limit = 0;
		goto again;
	}
	return p;
}

static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
{
	unsigned long usemap_snr, pgdat_snr;
	static unsigned long old_usemap_snr = NR_MEM_SECTIONS;
	static unsigned long old_pgdat_snr = NR_MEM_SECTIONS;
	struct pglist_data *pgdat = NODE_DATA(nid);
	int usemap_nid;

	usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
	pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
	if (usemap_snr == pgdat_snr)
		return;

	if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
		/* skip redundant message */
		return;

	old_usemap_snr = usemap_snr;
	old_pgdat_snr = pgdat_snr;

	usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
	if (usemap_nid != nid) {
		printk(KERN_INFO
		       "node %d must be removed before remove section %ld\n",
		       nid, usemap_snr);
		return;
	}
	/*
	 * There is a circular dependency.
	 * Some platforms allow un-removable section because they will just
	 * gather other removable sections for dynamic partitioning.
	 * Just notify un-removable section's number here.
	 */
	printk(KERN_INFO "Section %ld and %ld (node %d)", usemap_snr,
	       pgdat_snr, nid);
	printk(KERN_CONT
	       " have a circular dependency on usemap and pgdat allocations\n");
}
#else
static unsigned long * __init
sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
					 unsigned long size)
{
	return alloc_bootmem_node_nopanic(pgdat, size);
}

static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
{
}
#endif /* CONFIG_MEMORY_HOTREMOVE */

static void __init sparse_early_usemaps_alloc_node(unsigned long**usemap_map,
				 unsigned long pnum_begin,
				 unsigned long pnum_end,
				 unsigned long usemap_count, int nodeid)
{
	void *usemap;
	unsigned long pnum;
	int size = usemap_size();

	usemap = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nodeid),
							  size * usemap_count);
	if (!usemap) {
		printk(KERN_WARNING "%s: allocation failed\n", __func__);
		return;
	}

	for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
		if (!present_section_nr(pnum))
			continue;
		usemap_map[pnum] = usemap;
		usemap += size;
		check_usemap_section_nr(nodeid, usemap_map[pnum]);
	}
}

#ifndef CONFIG_SPARSEMEM_VMEMMAP
struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid)
{
	struct page *map;
	unsigned long size;

	map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
	if (map)
		return map;

	size = PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
	map = __alloc_bootmem_node_high(NODE_DATA(nid), size,
					 PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
	return map;
}
void __init sparse_mem_maps_populate_node(struct page **map_map,
					  unsigned long pnum_begin,
					  unsigned long pnum_end,
					  unsigned long map_count, int nodeid)
{
	void *map;
	unsigned long pnum;
	unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;

	map = alloc_remap(nodeid, size * map_count);
	if (map) {
		for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
			if (!present_section_nr(pnum))
				continue;
			map_map[pnum] = map;
			map += size;
		}
		return;
	}

	size = PAGE_ALIGN(size);
	map = __alloc_bootmem_node_high(NODE_DATA(nodeid), size * map_count,
					 PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
	if (map) {
		for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
			if (!present_section_nr(pnum))
				continue;
			map_map[pnum] = map;
			map += size;
		}
		return;
	}

	/* fallback */
	for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
		struct mem_section *ms;

		if (!present_section_nr(pnum))
			continue;
		map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
		if (map_map[pnum])
			continue;
		ms = __nr_to_section(pnum);
		printk(KERN_ERR "%s: sparsemem memory map backing failed "
			"some memory will not be available.\n", __func__);
		ms->section_mem_map = 0;
	}
}
#endif /* !CONFIG_SPARSEMEM_VMEMMAP */

#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
static void __init sparse_early_mem_maps_alloc_node(struct page **map_map,
				 unsigned long pnum_begin,
				 unsigned long pnum_end,
				 unsigned long map_count, int nodeid)
{
	sparse_mem_maps_populate_node(map_map, pnum_begin, pnum_end,
					 map_count, nodeid);
}
#else
static struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
{
	struct page *map;
	struct mem_section *ms = __nr_to_section(pnum);
	int nid = sparse_early_nid(ms);

	map = sparse_mem_map_populate(pnum, nid);
	if (map)
		return map;

	printk(KERN_ERR "%s: sparsemem memory map backing failed "
			"some memory will not be available.\n", __func__);
	ms->section_mem_map = 0;
	return NULL;
}
#endif

void __attribute__((weak)) __meminit vmemmap_populate_print_last(void)
{
}

/*
 * Allocate the accumulated non-linear sections, allocate a mem_map
 * for each and record the physical to section mapping.
 */
void __init sparse_init(void)
{
	unsigned long pnum;
	struct page *map;
	unsigned long *usemap;
	unsigned long **usemap_map;
	int size;
	int nodeid_begin = 0;
	unsigned long pnum_begin = 0;
	unsigned long usemap_count;
#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
	unsigned long map_count;
	int size2;
	struct page **map_map;
#endif

	/* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
	set_pageblock_order();

	/*
	 * map is using big page (aka 2M in x86 64 bit)
	 * usemap is less one page (aka 24 bytes)
	 * so alloc 2M (with 2M align) and 24 bytes in turn will
	 * make next 2M slip to one more 2M later.
	 * then in big system, the memory will have a lot of holes...
	 * here try to allocate 2M pages continuously.
	 *
	 * powerpc need to call sparse_init_one_section right after each
	 * sparse_early_mem_map_alloc, so allocate usemap_map at first.
	 */
	size = sizeof(unsigned long *) * NR_MEM_SECTIONS;
	usemap_map = alloc_bootmem(size);
	if (!usemap_map)
		panic("can not allocate usemap_map\n");

	for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
		struct mem_section *ms;

		if (!present_section_nr(pnum))
			continue;
		ms = __nr_to_section(pnum);
		nodeid_begin = sparse_early_nid(ms);
		pnum_begin = pnum;
		break;
	}
	usemap_count = 1;
	for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
		struct mem_section *ms;
		int nodeid;

		if (!present_section_nr(pnum))
			continue;
		ms = __nr_to_section(pnum);
		nodeid = sparse_early_nid(ms);
		if (nodeid == nodeid_begin) {
			usemap_count++;
			continue;
		}
		/* ok, we need to take cake of from pnum_begin to pnum - 1*/
		sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, pnum,
						 usemap_count, nodeid_begin);
		/* new start, update count etc*/
		nodeid_begin = nodeid;
		pnum_begin = pnum;
		usemap_count = 1;
	}
	/* ok, last chunk */
	sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, NR_MEM_SECTIONS,
					 usemap_count, nodeid_begin);

#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
	size2 = sizeof(struct page *) * NR_MEM_SECTIONS;
	map_map = alloc_bootmem(size2);
	if (!map_map)
		panic("can not allocate map_map\n");

	for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
		struct mem_section *ms;

		if (!present_section_nr(pnum))
			continue;
		ms = __nr_to_section(pnum);
		nodeid_begin = sparse_early_nid(ms);
		pnum_begin = pnum;
		break;
	}
	map_count = 1;
	for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
		struct mem_section *ms;
		int nodeid;

		if (!present_section_nr(pnum))
			continue;
		ms = __nr_to_section(pnum);
		nodeid = sparse_early_nid(ms);
		if (nodeid == nodeid_begin) {
			map_count++;
			continue;
		}
		/* ok, we need to take cake of from pnum_begin to pnum - 1*/
		sparse_early_mem_maps_alloc_node(map_map, pnum_begin, pnum,
						 map_count, nodeid_begin);
		/* new start, update count etc*/
		nodeid_begin = nodeid;
		pnum_begin = pnum;
		map_count = 1;
	}
	/* ok, last chunk */
	sparse_early_mem_maps_alloc_node(map_map, pnum_begin, NR_MEM_SECTIONS,
					 map_count, nodeid_begin);
#endif

	for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
		if (!present_section_nr(pnum))
			continue;

		usemap = usemap_map[pnum];
		if (!usemap)
			continue;

#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
		map = map_map[pnum];
#else
		map = sparse_early_mem_map_alloc(pnum);
#endif
		if (!map)
			continue;

		sparse_init_one_section(__nr_to_section(pnum), pnum, map,
								usemap);
	}

	vmemmap_populate_print_last();

#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
	free_bootmem(__pa(map_map), size2);
#endif
	free_bootmem(__pa(usemap_map), size);
}

#ifdef CONFIG_MEMORY_HOTPLUG
#ifdef CONFIG_SPARSEMEM_VMEMMAP
static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
						 unsigned long nr_pages)
{
	/* This will make the necessary allocations eventually. */
	return sparse_mem_map_populate(pnum, nid);
}
static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
{
	return; /* XXX: Not implemented yet */
}
static void free_map_bootmem(struct page *page, unsigned long nr_pages)
{
}
#else
static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
{
	struct page *page, *ret;
	unsigned long memmap_size = sizeof(struct page) * nr_pages;

	page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
	if (page)
		goto got_map_page;

	ret = vmalloc(memmap_size);
	if (ret)
		goto got_map_ptr;

	return NULL;
got_map_page:
	ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
got_map_ptr:
	memset(ret, 0, memmap_size);

	return ret;
}

static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
						  unsigned long nr_pages)
{
	return __kmalloc_section_memmap(nr_pages);
}

static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
{
	if (is_vmalloc_addr(memmap))
		vfree(memmap);
	else
		free_pages((unsigned long)memmap,
			   get_order(sizeof(struct page) * nr_pages));
}

static void free_map_bootmem(struct page *page, unsigned long nr_pages)
{
	unsigned long maps_section_nr, removing_section_nr, i;
	unsigned long magic;

	for (i = 0; i < nr_pages; i++, page++) {
		magic = (unsigned long) page->lru.next;

		BUG_ON(magic == NODE_INFO);

		maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
		removing_section_nr = page->private;

		/*
		 * When this function is called, the removing section is
		 * logical offlined state. This means all pages are isolated
		 * from page allocator. If removing section's memmap is placed
		 * on the same section, it must not be freed.
		 * If it is freed, page allocator may allocate it which will
		 * be removed physically soon.
		 */
		if (maps_section_nr != removing_section_nr)
			put_page_bootmem(page);
	}
}
#endif /* CONFIG_SPARSEMEM_VMEMMAP */

static void free_section_usemap(struct page *memmap, unsigned long *usemap)
{
	struct page *usemap_page;
	unsigned long nr_pages;

	if (!usemap)
		return;

	usemap_page = virt_to_page(usemap);
	/*
	 * Check to see if allocation came from hot-plug-add
	 */
	if (PageSlab(usemap_page)) {
		kfree(usemap);
		if (memmap)
			__kfree_section_memmap(memmap, PAGES_PER_SECTION);
		return;
	}

	/*
	 * The usemap came from bootmem. This is packed with other usemaps
	 * on the section which has pgdat at boot time. Just keep it as is now.
	 */

	if (memmap) {
		struct page *memmap_page;
		memmap_page = virt_to_page(memmap);

		nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
			>> PAGE_SHIFT;

		free_map_bootmem(memmap_page, nr_pages);
	}
}

/*
 * returns the number of sections whose mem_maps were properly
 * set.  If this is <=0, then that means that the passed-in
 * map was not consumed and must be freed.
 */
int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
			   int nr_pages)
{
	unsigned long section_nr = pfn_to_section_nr(start_pfn);
	struct pglist_data *pgdat = zone->zone_pgdat;
	struct mem_section *ms;
	struct page *memmap;
	unsigned long *usemap;
	unsigned long flags;
	int ret;

	/*
	 * no locking for this, because it does its own
	 * plus, it does a kmalloc
	 */
	ret = sparse_index_init(section_nr, pgdat->node_id);
	if (ret < 0 && ret != -EEXIST)
		return ret;
	memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, nr_pages);
	if (!memmap)
		return -ENOMEM;
	usemap = __kmalloc_section_usemap();
	if (!usemap) {
		__kfree_section_memmap(memmap, nr_pages);
		return -ENOMEM;
	}

	pgdat_resize_lock(pgdat, &flags);

	ms = __pfn_to_section(start_pfn);
	if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
		ret = -EEXIST;
		goto out;
	}

	ms->section_mem_map |= SECTION_MARKED_PRESENT;

	ret = sparse_init_one_section(ms, section_nr, memmap, usemap);

out:
	pgdat_resize_unlock(pgdat, &flags);
	if (ret <= 0) {
		kfree(usemap);
		__kfree_section_memmap(memmap, nr_pages);
	}
	return ret;
}

void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
{
	struct page *memmap = NULL;
	unsigned long *usemap = NULL;

	if (ms->section_mem_map) {
		usemap = ms->pageblock_flags;
		memmap = sparse_decode_mem_map(ms->section_mem_map,
						__section_nr(ms));
		ms->section_mem_map = 0;
		ms->pageblock_flags = NULL;
	}

	free_section_usemap(memmap, usemap);
}
#endif