1 // SPDX-License-Identifier: GPL-2.0
3 * sparse memory mappings.
6 #include <linux/slab.h>
7 #include <linux/mmzone.h>
8 #include <linux/memblock.h>
9 #include <linux/compiler.h>
10 #include <linux/highmem.h>
11 #include <linux/export.h>
12 #include <linux/spinlock.h>
13 #include <linux/vmalloc.h>
17 #include <asm/pgalloc.h>
18 #include <asm/pgtable.h>
21 * Permanent SPARSEMEM data:
23 * 1) mem_section - memory sections, mem_map's for valid memory
25 #ifdef CONFIG_SPARSEMEM_EXTREME
26 struct mem_section **mem_section;
28 struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
29 ____cacheline_internodealigned_in_smp;
31 EXPORT_SYMBOL(mem_section);
33 #ifdef NODE_NOT_IN_PAGE_FLAGS
35 * If we did not store the node number in the page then we have to
36 * do a lookup in the section_to_node_table in order to find which
37 * node the page belongs to.
39 #if MAX_NUMNODES <= 256
40 static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
42 static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
45 int page_to_nid(const struct page *page)
47 return section_to_node_table[page_to_section(page)];
49 EXPORT_SYMBOL(page_to_nid);
51 static void set_section_nid(unsigned long section_nr, int nid)
53 section_to_node_table[section_nr] = nid;
55 #else /* !NODE_NOT_IN_PAGE_FLAGS */
56 static inline void set_section_nid(unsigned long section_nr, int nid)
61 #ifdef CONFIG_SPARSEMEM_EXTREME
62 static noinline struct mem_section __ref *sparse_index_alloc(int nid)
64 struct mem_section *section = NULL;
65 unsigned long array_size = SECTIONS_PER_ROOT *
66 sizeof(struct mem_section);
68 if (slab_is_available()) {
69 section = kzalloc_node(array_size, GFP_KERNEL, nid);
71 section = memblock_alloc_node(array_size, SMP_CACHE_BYTES,
74 panic("%s: Failed to allocate %lu bytes nid=%d\n",
75 __func__, array_size, nid);
81 static int __meminit sparse_index_init(unsigned long section_nr, int nid)
83 unsigned long root = SECTION_NR_TO_ROOT(section_nr);
84 struct mem_section *section;
86 if (mem_section[root])
89 section = sparse_index_alloc(nid);
93 mem_section[root] = section;
97 #else /* !SPARSEMEM_EXTREME */
98 static inline int sparse_index_init(unsigned long section_nr, int nid)
104 #ifdef CONFIG_SPARSEMEM_EXTREME
105 unsigned long __section_nr(struct mem_section *ms)
107 unsigned long root_nr;
108 struct mem_section *root = NULL;
110 for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
111 root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
115 if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
121 return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
124 unsigned long __section_nr(struct mem_section *ms)
126 return (unsigned long)(ms - mem_section[0]);
131 * During early boot, before section_mem_map is used for an actual
132 * mem_map, we use section_mem_map to store the section's NUMA
133 * node. This keeps us from having to use another data structure. The
134 * node information is cleared just before we store the real mem_map.
136 static inline unsigned long sparse_encode_early_nid(int nid)
138 return (nid << SECTION_NID_SHIFT);
141 static inline int sparse_early_nid(struct mem_section *section)
143 return (section->section_mem_map >> SECTION_NID_SHIFT);
146 /* Validate the physical addressing limitations of the model */
147 void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
148 unsigned long *end_pfn)
150 unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
153 * Sanity checks - do not allow an architecture to pass
154 * in larger pfns than the maximum scope of sparsemem:
156 if (*start_pfn > max_sparsemem_pfn) {
157 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
158 "Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
159 *start_pfn, *end_pfn, max_sparsemem_pfn);
161 *start_pfn = max_sparsemem_pfn;
162 *end_pfn = max_sparsemem_pfn;
163 } else if (*end_pfn > max_sparsemem_pfn) {
164 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
165 "End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
166 *start_pfn, *end_pfn, max_sparsemem_pfn);
168 *end_pfn = max_sparsemem_pfn;
173 * There are a number of times that we loop over NR_MEM_SECTIONS,
174 * looking for section_present() on each. But, when we have very
175 * large physical address spaces, NR_MEM_SECTIONS can also be
176 * very large which makes the loops quite long.
178 * Keeping track of this gives us an easy way to break out of
181 unsigned long __highest_present_section_nr;
182 static void section_mark_present(struct mem_section *ms)
184 unsigned long section_nr = __section_nr(ms);
186 if (section_nr > __highest_present_section_nr)
187 __highest_present_section_nr = section_nr;
189 ms->section_mem_map |= SECTION_MARKED_PRESENT;
192 static inline unsigned long next_present_section_nr(unsigned long section_nr)
196 if (present_section_nr(section_nr))
198 } while ((section_nr <= __highest_present_section_nr));
202 #define for_each_present_section_nr(start, section_nr) \
203 for (section_nr = next_present_section_nr(start-1); \
204 ((section_nr != -1) && \
205 (section_nr <= __highest_present_section_nr)); \
206 section_nr = next_present_section_nr(section_nr))
208 static inline unsigned long first_present_section_nr(void)
210 return next_present_section_nr(-1);
213 void subsection_mask_set(unsigned long *map, unsigned long pfn,
214 unsigned long nr_pages)
216 int idx = subsection_map_index(pfn);
217 int end = subsection_map_index(pfn + nr_pages - 1);
219 bitmap_set(map, idx, end - idx + 1);
222 void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
224 int end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
225 int i, start_sec = pfn_to_section_nr(pfn);
230 for (i = start_sec; i <= end_sec; i++) {
231 struct mem_section *ms;
234 pfns = min(nr_pages, PAGES_PER_SECTION
235 - (pfn & ~PAGE_SECTION_MASK));
236 ms = __nr_to_section(i);
237 subsection_mask_set(ms->usage->subsection_map, pfn, pfns);
239 pr_debug("%s: sec: %d pfns: %ld set(%d, %d)\n", __func__, i,
240 pfns, subsection_map_index(pfn),
241 subsection_map_index(pfn + pfns - 1));
248 /* Record a memory area against a node. */
249 void __init memory_present(int nid, unsigned long start, unsigned long end)
253 #ifdef CONFIG_SPARSEMEM_EXTREME
254 if (unlikely(!mem_section)) {
255 unsigned long size, align;
257 size = sizeof(struct mem_section*) * NR_SECTION_ROOTS;
258 align = 1 << (INTERNODE_CACHE_SHIFT);
259 mem_section = memblock_alloc(size, align);
261 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
262 __func__, size, align);
266 start &= PAGE_SECTION_MASK;
267 mminit_validate_memmodel_limits(&start, &end);
268 for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
269 unsigned long section = pfn_to_section_nr(pfn);
270 struct mem_section *ms;
272 sparse_index_init(section, nid);
273 set_section_nid(section, nid);
275 ms = __nr_to_section(section);
276 if (!ms->section_mem_map) {
277 ms->section_mem_map = sparse_encode_early_nid(nid) |
279 section_mark_present(ms);
285 * Mark all memblocks as present using memory_present(). This is a
286 * convienence function that is useful for a number of arches
287 * to mark all of the systems memory as present during initialization.
289 void __init memblocks_present(void)
291 struct memblock_region *reg;
293 for_each_memblock(memory, reg) {
294 memory_present(memblock_get_region_node(reg),
295 memblock_region_memory_base_pfn(reg),
296 memblock_region_memory_end_pfn(reg));
301 * Subtle, we encode the real pfn into the mem_map such that
302 * the identity pfn - section_mem_map will return the actual
303 * physical page frame number.
305 static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
307 unsigned long coded_mem_map =
308 (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
309 BUILD_BUG_ON(SECTION_MAP_LAST_BIT > (1UL<<PFN_SECTION_SHIFT));
310 BUG_ON(coded_mem_map & ~SECTION_MAP_MASK);
311 return coded_mem_map;
315 * Decode mem_map from the coded memmap
317 struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
319 /* mask off the extra low bits of information */
320 coded_mem_map &= SECTION_MAP_MASK;
321 return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
324 static void __meminit sparse_init_one_section(struct mem_section *ms,
325 unsigned long pnum, struct page *mem_map,
326 struct mem_section_usage *usage, unsigned long flags)
328 ms->section_mem_map &= ~SECTION_MAP_MASK;
329 ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum)
330 | SECTION_HAS_MEM_MAP | flags;
334 static unsigned long usemap_size(void)
336 return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
339 size_t mem_section_usage_size(void)
341 return sizeof(struct mem_section_usage) + usemap_size();
344 #ifdef CONFIG_MEMORY_HOTREMOVE
345 static struct mem_section_usage * __init
346 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
349 struct mem_section_usage *usage;
350 unsigned long goal, limit;
353 * A page may contain usemaps for other sections preventing the
354 * page being freed and making a section unremovable while
355 * other sections referencing the usemap remain active. Similarly,
356 * a pgdat can prevent a section being removed. If section A
357 * contains a pgdat and section B contains the usemap, both
358 * sections become inter-dependent. This allocates usemaps
359 * from the same section as the pgdat where possible to avoid
362 goal = __pa(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
363 limit = goal + (1UL << PA_SECTION_SHIFT);
364 nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
366 usage = memblock_alloc_try_nid(size, SMP_CACHE_BYTES, goal, limit, nid);
367 if (!usage && limit) {
374 static void __init check_usemap_section_nr(int nid,
375 struct mem_section_usage *usage)
377 unsigned long usemap_snr, pgdat_snr;
378 static unsigned long old_usemap_snr;
379 static unsigned long old_pgdat_snr;
380 struct pglist_data *pgdat = NODE_DATA(nid);
384 if (!old_usemap_snr) {
385 old_usemap_snr = NR_MEM_SECTIONS;
386 old_pgdat_snr = NR_MEM_SECTIONS;
389 usemap_snr = pfn_to_section_nr(__pa(usage) >> PAGE_SHIFT);
390 pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
391 if (usemap_snr == pgdat_snr)
394 if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
395 /* skip redundant message */
398 old_usemap_snr = usemap_snr;
399 old_pgdat_snr = pgdat_snr;
401 usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
402 if (usemap_nid != nid) {
403 pr_info("node %d must be removed before remove section %ld\n",
408 * There is a circular dependency.
409 * Some platforms allow un-removable section because they will just
410 * gather other removable sections for dynamic partitioning.
411 * Just notify un-removable section's number here.
413 pr_info("Section %ld and %ld (node %d) have a circular dependency on usemap and pgdat allocations\n",
414 usemap_snr, pgdat_snr, nid);
417 static struct mem_section_usage * __init
418 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
421 return memblock_alloc_node(size, SMP_CACHE_BYTES, pgdat->node_id);
424 static void __init check_usemap_section_nr(int nid,
425 struct mem_section_usage *usage)
428 #endif /* CONFIG_MEMORY_HOTREMOVE */
430 #ifdef CONFIG_SPARSEMEM_VMEMMAP
431 static unsigned long __init section_map_size(void)
433 return ALIGN(sizeof(struct page) * PAGES_PER_SECTION, PMD_SIZE);
437 static unsigned long __init section_map_size(void)
439 return PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
442 struct page __init *__populate_section_memmap(unsigned long pfn,
443 unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
445 unsigned long size = section_map_size();
446 struct page *map = sparse_buffer_alloc(size);
447 phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
452 map = memblock_alloc_try_nid(size,
454 MEMBLOCK_ALLOC_ACCESSIBLE, nid);
456 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%pa\n",
457 __func__, size, PAGE_SIZE, nid, &addr);
461 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
463 static void *sparsemap_buf __meminitdata;
464 static void *sparsemap_buf_end __meminitdata;
466 static void __init sparse_buffer_init(unsigned long size, int nid)
468 phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
469 WARN_ON(sparsemap_buf); /* forgot to call sparse_buffer_fini()? */
471 memblock_alloc_try_nid_raw(size, PAGE_SIZE,
473 MEMBLOCK_ALLOC_ACCESSIBLE, nid);
474 sparsemap_buf_end = sparsemap_buf + size;
477 static void __init sparse_buffer_fini(void)
479 unsigned long size = sparsemap_buf_end - sparsemap_buf;
481 if (sparsemap_buf && size > 0)
482 memblock_free_early(__pa(sparsemap_buf), size);
483 sparsemap_buf = NULL;
486 void * __meminit sparse_buffer_alloc(unsigned long size)
491 ptr = PTR_ALIGN(sparsemap_buf, size);
492 if (ptr + size > sparsemap_buf_end)
495 sparsemap_buf = ptr + size;
500 void __weak __meminit vmemmap_populate_print_last(void)
505 * Initialize sparse on a specific node. The node spans [pnum_begin, pnum_end)
506 * And number of present sections in this node is map_count.
508 static void __init sparse_init_nid(int nid, unsigned long pnum_begin,
509 unsigned long pnum_end,
510 unsigned long map_count)
512 struct mem_section_usage *usage;
516 usage = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nid),
517 mem_section_usage_size() * map_count);
519 pr_err("%s: node[%d] usemap allocation failed", __func__, nid);
522 sparse_buffer_init(map_count * section_map_size(), nid);
523 for_each_present_section_nr(pnum_begin, pnum) {
524 unsigned long pfn = section_nr_to_pfn(pnum);
526 if (pnum >= pnum_end)
529 map = __populate_section_memmap(pfn, PAGES_PER_SECTION,
532 pr_err("%s: node[%d] memory map backing failed. Some memory will not be available.",
537 check_usemap_section_nr(nid, usage);
538 sparse_init_one_section(__nr_to_section(pnum), pnum, map, usage,
540 usage = (void *) usage + mem_section_usage_size();
542 sparse_buffer_fini();
545 /* We failed to allocate, mark all the following pnums as not present */
546 for_each_present_section_nr(pnum_begin, pnum) {
547 struct mem_section *ms;
549 if (pnum >= pnum_end)
551 ms = __nr_to_section(pnum);
552 ms->section_mem_map = 0;
557 * Allocate the accumulated non-linear sections, allocate a mem_map
558 * for each and record the physical to section mapping.
560 void __init sparse_init(void)
562 unsigned long pnum_begin = first_present_section_nr();
563 int nid_begin = sparse_early_nid(__nr_to_section(pnum_begin));
564 unsigned long pnum_end, map_count = 1;
566 /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
567 set_pageblock_order();
569 for_each_present_section_nr(pnum_begin + 1, pnum_end) {
570 int nid = sparse_early_nid(__nr_to_section(pnum_end));
572 if (nid == nid_begin) {
576 /* Init node with sections in range [pnum_begin, pnum_end) */
577 sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
579 pnum_begin = pnum_end;
582 /* cover the last node */
583 sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
584 vmemmap_populate_print_last();
587 #ifdef CONFIG_MEMORY_HOTPLUG
589 /* Mark all memory sections within the pfn range as online */
590 void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
594 for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
595 unsigned long section_nr = pfn_to_section_nr(pfn);
596 struct mem_section *ms;
598 /* onlining code should never touch invalid ranges */
599 if (WARN_ON(!valid_section_nr(section_nr)))
602 ms = __nr_to_section(section_nr);
603 ms->section_mem_map |= SECTION_IS_ONLINE;
607 #ifdef CONFIG_MEMORY_HOTREMOVE
608 /* Mark all memory sections within the pfn range as offline */
609 void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
613 for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
614 unsigned long section_nr = pfn_to_section_nr(pfn);
615 struct mem_section *ms;
618 * TODO this needs some double checking. Offlining code makes
619 * sure to check pfn_valid but those checks might be just bogus
621 if (WARN_ON(!valid_section_nr(section_nr)))
624 ms = __nr_to_section(section_nr);
625 ms->section_mem_map &= ~SECTION_IS_ONLINE;
630 #ifdef CONFIG_SPARSEMEM_VMEMMAP
631 static struct page *populate_section_memmap(unsigned long pfn,
632 unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
634 return __populate_section_memmap(pfn, nr_pages, nid, altmap);
637 static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
638 struct vmem_altmap *altmap)
640 unsigned long start = (unsigned long) pfn_to_page(pfn);
641 unsigned long end = start + nr_pages * sizeof(struct page);
643 vmemmap_free(start, end, altmap);
645 static void free_map_bootmem(struct page *memmap)
647 unsigned long start = (unsigned long)memmap;
648 unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
650 vmemmap_free(start, end, NULL);
653 struct page *populate_section_memmap(unsigned long pfn,
654 unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
656 struct page *page, *ret;
657 unsigned long memmap_size = sizeof(struct page) * PAGES_PER_SECTION;
659 page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
663 ret = vmalloc(memmap_size);
669 ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
675 static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
676 struct vmem_altmap *altmap)
678 struct page *memmap = pfn_to_page(pfn);
680 if (is_vmalloc_addr(memmap))
683 free_pages((unsigned long)memmap,
684 get_order(sizeof(struct page) * PAGES_PER_SECTION));
687 static void free_map_bootmem(struct page *memmap)
689 unsigned long maps_section_nr, removing_section_nr, i;
690 unsigned long magic, nr_pages;
691 struct page *page = virt_to_page(memmap);
693 nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
696 for (i = 0; i < nr_pages; i++, page++) {
697 magic = (unsigned long) page->freelist;
699 BUG_ON(magic == NODE_INFO);
701 maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
702 removing_section_nr = page_private(page);
705 * When this function is called, the removing section is
706 * logical offlined state. This means all pages are isolated
707 * from page allocator. If removing section's memmap is placed
708 * on the same section, it must not be freed.
709 * If it is freed, page allocator may allocate it which will
710 * be removed physically soon.
712 if (maps_section_nr != removing_section_nr)
713 put_page_bootmem(page);
716 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
719 * sparse_add_one_section - add a memory section
720 * @nid: The node to add section on
721 * @start_pfn: start pfn of the memory range
722 * @altmap: device page map
724 * This is only intended for hotplug.
728 * * -EEXIST - Section has been present.
729 * * -ENOMEM - Out of memory.
731 int __meminit sparse_add_section(int nid, unsigned long start_pfn,
732 unsigned long nr_pages, struct vmem_altmap *altmap)
734 unsigned long section_nr = pfn_to_section_nr(start_pfn);
735 struct mem_section_usage *usage;
736 struct mem_section *ms;
741 * no locking for this, because it does its own
742 * plus, it does a kmalloc
744 ret = sparse_index_init(section_nr, nid);
745 if (ret < 0 && ret != -EEXIST)
748 memmap = populate_section_memmap(start_pfn, PAGES_PER_SECTION, nid,
752 usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
754 depopulate_section_memmap(start_pfn, PAGES_PER_SECTION, altmap);
758 ms = __pfn_to_section(start_pfn);
759 if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
765 * Poison uninitialized struct pages in order to catch invalid flags
768 page_init_poison(memmap, sizeof(struct page) * PAGES_PER_SECTION);
770 set_section_nid(section_nr, nid);
771 section_mark_present(ms);
772 sparse_init_one_section(ms, section_nr, memmap, usage, 0);
777 depopulate_section_memmap(start_pfn, PAGES_PER_SECTION, altmap);
782 #ifdef CONFIG_MEMORY_FAILURE
783 static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
791 * A further optimization is to have per section refcounted
792 * num_poisoned_pages. But that would need more space per memmap, so
793 * for now just do a quick global check to speed up this routine in the
794 * absence of bad pages.
796 if (atomic_long_read(&num_poisoned_pages) == 0)
799 for (i = 0; i < nr_pages; i++) {
800 if (PageHWPoison(&memmap[i])) {
801 atomic_long_sub(1, &num_poisoned_pages);
802 ClearPageHWPoison(&memmap[i]);
807 static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
812 static void free_section_usage(struct mem_section *ms, struct page *memmap,
813 struct mem_section_usage *usage, unsigned long pfn,
814 unsigned long nr_pages, struct vmem_altmap *altmap)
820 * Check to see if allocation came from hot-plug-add
822 if (!early_section(ms)) {
825 depopulate_section_memmap(pfn, nr_pages, altmap);
830 * The usemap came from bootmem. This is packed with other usemaps
831 * on the section which has pgdat at boot time. Just keep it as is now.
835 free_map_bootmem(memmap);
838 void sparse_remove_one_section(struct mem_section *ms, unsigned long pfn,
839 unsigned long nr_pages, unsigned long map_offset,
840 struct vmem_altmap *altmap)
842 struct page *memmap = NULL;
843 struct mem_section_usage *usage = NULL;
845 if (ms->section_mem_map) {
847 memmap = sparse_decode_mem_map(ms->section_mem_map,
849 ms->section_mem_map = 0;
853 clear_hwpoisoned_pages(memmap + map_offset, nr_pages - map_offset);
854 free_section_usage(ms, memmap, usage, pfn, nr_pages, altmap);
856 #endif /* CONFIG_MEMORY_HOTPLUG */