1 // SPDX-License-Identifier: GPL-2.0
3 * sparse memory mappings.
6 #include <linux/slab.h>
7 #include <linux/mmzone.h>
8 #include <linux/bootmem.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_virt_alloc_node(array_size, nid);
76 static int __meminit sparse_index_init(unsigned long section_nr, int nid)
78 unsigned long root = SECTION_NR_TO_ROOT(section_nr);
79 struct mem_section *section;
81 if (mem_section[root])
84 section = sparse_index_alloc(nid);
88 mem_section[root] = section;
92 #else /* !SPARSEMEM_EXTREME */
93 static inline int sparse_index_init(unsigned long section_nr, int nid)
99 #ifdef CONFIG_SPARSEMEM_EXTREME
100 int __section_nr(struct mem_section* ms)
102 unsigned long root_nr;
103 struct mem_section *root = NULL;
105 for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
106 root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
110 if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
116 return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
119 int __section_nr(struct mem_section* ms)
121 return (int)(ms - mem_section[0]);
126 * During early boot, before section_mem_map is used for an actual
127 * mem_map, we use section_mem_map to store the section's NUMA
128 * node. This keeps us from having to use another data structure. The
129 * node information is cleared just before we store the real mem_map.
131 static inline unsigned long sparse_encode_early_nid(int nid)
133 return (nid << SECTION_NID_SHIFT);
136 static inline int sparse_early_nid(struct mem_section *section)
138 return (section->section_mem_map >> SECTION_NID_SHIFT);
141 /* Validate the physical addressing limitations of the model */
142 void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
143 unsigned long *end_pfn)
145 unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
148 * Sanity checks - do not allow an architecture to pass
149 * in larger pfns than the maximum scope of sparsemem:
151 if (*start_pfn > max_sparsemem_pfn) {
152 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
153 "Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
154 *start_pfn, *end_pfn, max_sparsemem_pfn);
156 *start_pfn = max_sparsemem_pfn;
157 *end_pfn = max_sparsemem_pfn;
158 } else if (*end_pfn > max_sparsemem_pfn) {
159 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
160 "End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
161 *start_pfn, *end_pfn, max_sparsemem_pfn);
163 *end_pfn = max_sparsemem_pfn;
168 * There are a number of times that we loop over NR_MEM_SECTIONS,
169 * looking for section_present() on each. But, when we have very
170 * large physical address spaces, NR_MEM_SECTIONS can also be
171 * very large which makes the loops quite long.
173 * Keeping track of this gives us an easy way to break out of
176 int __highest_present_section_nr;
177 static void section_mark_present(struct mem_section *ms)
179 int section_nr = __section_nr(ms);
181 if (section_nr > __highest_present_section_nr)
182 __highest_present_section_nr = section_nr;
184 ms->section_mem_map |= SECTION_MARKED_PRESENT;
187 static inline int next_present_section_nr(int section_nr)
191 if (present_section_nr(section_nr))
193 } while ((section_nr < NR_MEM_SECTIONS) &&
194 (section_nr <= __highest_present_section_nr));
198 #define for_each_present_section_nr(start, section_nr) \
199 for (section_nr = next_present_section_nr(start-1); \
200 ((section_nr >= 0) && \
201 (section_nr < NR_MEM_SECTIONS) && \
202 (section_nr <= __highest_present_section_nr)); \
203 section_nr = next_present_section_nr(section_nr))
205 /* Record a memory area against a node. */
206 void __init memory_present(int nid, unsigned long start, unsigned long end)
210 #ifdef CONFIG_SPARSEMEM_EXTREME
211 if (unlikely(!mem_section)) {
212 unsigned long size, align;
214 size = sizeof(struct mem_section) * NR_SECTION_ROOTS;
215 align = 1 << (INTERNODE_CACHE_SHIFT);
216 mem_section = memblock_virt_alloc(size, align);
220 start &= PAGE_SECTION_MASK;
221 mminit_validate_memmodel_limits(&start, &end);
222 for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
223 unsigned long section = pfn_to_section_nr(pfn);
224 struct mem_section *ms;
226 sparse_index_init(section, nid);
227 set_section_nid(section, nid);
229 ms = __nr_to_section(section);
230 if (!ms->section_mem_map) {
231 ms->section_mem_map = sparse_encode_early_nid(nid) |
233 section_mark_present(ms);
239 * Only used by the i386 NUMA architecures, but relatively
242 unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
243 unsigned long end_pfn)
246 unsigned long nr_pages = 0;
248 mminit_validate_memmodel_limits(&start_pfn, &end_pfn);
249 for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
250 if (nid != early_pfn_to_nid(pfn))
253 if (pfn_present(pfn))
254 nr_pages += PAGES_PER_SECTION;
257 return nr_pages * sizeof(struct page);
261 * Subtle, we encode the real pfn into the mem_map such that
262 * the identity pfn - section_mem_map will return the actual
263 * physical page frame number.
265 static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
267 return (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
271 * Decode mem_map from the coded memmap
273 struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
275 /* mask off the extra low bits of information */
276 coded_mem_map &= SECTION_MAP_MASK;
277 return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
280 static int __meminit sparse_init_one_section(struct mem_section *ms,
281 unsigned long pnum, struct page *mem_map,
282 unsigned long *pageblock_bitmap)
284 if (!present_section(ms))
287 ms->section_mem_map &= ~SECTION_MAP_MASK;
288 ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
290 ms->pageblock_flags = pageblock_bitmap;
295 unsigned long usemap_size(void)
297 return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
300 #ifdef CONFIG_MEMORY_HOTPLUG
301 static unsigned long *__kmalloc_section_usemap(void)
303 return kmalloc(usemap_size(), GFP_KERNEL);
305 #endif /* CONFIG_MEMORY_HOTPLUG */
307 #ifdef CONFIG_MEMORY_HOTREMOVE
308 static unsigned long * __init
309 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
312 unsigned long goal, limit;
316 * A page may contain usemaps for other sections preventing the
317 * page being freed and making a section unremovable while
318 * other sections referencing the usemap remain active. Similarly,
319 * a pgdat can prevent a section being removed. If section A
320 * contains a pgdat and section B contains the usemap, both
321 * sections become inter-dependent. This allocates usemaps
322 * from the same section as the pgdat where possible to avoid
325 goal = __pa(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
326 limit = goal + (1UL << PA_SECTION_SHIFT);
327 nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
329 p = memblock_virt_alloc_try_nid_nopanic(size,
330 SMP_CACHE_BYTES, goal, limit,
339 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
341 unsigned long usemap_snr, pgdat_snr;
342 static unsigned long old_usemap_snr;
343 static unsigned long old_pgdat_snr;
344 struct pglist_data *pgdat = NODE_DATA(nid);
348 if (!old_usemap_snr) {
349 old_usemap_snr = NR_MEM_SECTIONS;
350 old_pgdat_snr = NR_MEM_SECTIONS;
353 usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
354 pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
355 if (usemap_snr == pgdat_snr)
358 if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
359 /* skip redundant message */
362 old_usemap_snr = usemap_snr;
363 old_pgdat_snr = pgdat_snr;
365 usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
366 if (usemap_nid != nid) {
367 pr_info("node %d must be removed before remove section %ld\n",
372 * There is a circular dependency.
373 * Some platforms allow un-removable section because they will just
374 * gather other removable sections for dynamic partitioning.
375 * Just notify un-removable section's number here.
377 pr_info("Section %ld and %ld (node %d) have a circular dependency on usemap and pgdat allocations\n",
378 usemap_snr, pgdat_snr, nid);
381 static unsigned long * __init
382 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
385 return memblock_virt_alloc_node_nopanic(size, pgdat->node_id);
388 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
391 #endif /* CONFIG_MEMORY_HOTREMOVE */
393 static void __init sparse_early_usemaps_alloc_node(void *data,
394 unsigned long pnum_begin,
395 unsigned long pnum_end,
396 unsigned long usemap_count, int nodeid)
400 unsigned long **usemap_map = (unsigned long **)data;
401 int size = usemap_size();
403 usemap = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nodeid),
404 size * usemap_count);
406 pr_warn("%s: allocation failed\n", __func__);
410 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
411 if (!present_section_nr(pnum))
413 usemap_map[pnum] = usemap;
415 check_usemap_section_nr(nodeid, usemap_map[pnum]);
419 #ifndef CONFIG_SPARSEMEM_VMEMMAP
420 struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid)
425 map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
429 size = PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
430 map = memblock_virt_alloc_try_nid(size,
431 PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
432 BOOTMEM_ALLOC_ACCESSIBLE, nid);
435 void __init sparse_mem_maps_populate_node(struct page **map_map,
436 unsigned long pnum_begin,
437 unsigned long pnum_end,
438 unsigned long map_count, int nodeid)
442 unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
444 map = alloc_remap(nodeid, size * map_count);
446 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
447 if (!present_section_nr(pnum))
455 size = PAGE_ALIGN(size);
456 map = memblock_virt_alloc_try_nid_raw(size * map_count,
457 PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
458 BOOTMEM_ALLOC_ACCESSIBLE, nodeid);
460 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
461 if (!present_section_nr(pnum))
470 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
471 struct mem_section *ms;
473 if (!present_section_nr(pnum))
475 map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
478 ms = __nr_to_section(pnum);
479 pr_err("%s: sparsemem memory map backing failed some memory will not be available\n",
481 ms->section_mem_map = 0;
484 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
486 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
487 static void __init sparse_early_mem_maps_alloc_node(void *data,
488 unsigned long pnum_begin,
489 unsigned long pnum_end,
490 unsigned long map_count, int nodeid)
492 struct page **map_map = (struct page **)data;
493 sparse_mem_maps_populate_node(map_map, pnum_begin, pnum_end,
497 static struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
500 struct mem_section *ms = __nr_to_section(pnum);
501 int nid = sparse_early_nid(ms);
503 map = sparse_mem_map_populate(pnum, nid);
507 pr_err("%s: sparsemem memory map backing failed some memory will not be available\n",
509 ms->section_mem_map = 0;
514 void __weak __meminit vmemmap_populate_print_last(void)
519 * alloc_usemap_and_memmap - memory alloction for pageblock flags and vmemmap
520 * @map: usemap_map for pageblock flags or mmap_map for vmemmap
522 static void __init alloc_usemap_and_memmap(void (*alloc_func)
523 (void *, unsigned long, unsigned long,
524 unsigned long, int), void *data)
527 unsigned long map_count;
528 int nodeid_begin = 0;
529 unsigned long pnum_begin = 0;
531 for_each_present_section_nr(0, pnum) {
532 struct mem_section *ms;
534 ms = __nr_to_section(pnum);
535 nodeid_begin = sparse_early_nid(ms);
540 for_each_present_section_nr(pnum_begin + 1, pnum) {
541 struct mem_section *ms;
544 ms = __nr_to_section(pnum);
545 nodeid = sparse_early_nid(ms);
546 if (nodeid == nodeid_begin) {
550 /* ok, we need to take cake of from pnum_begin to pnum - 1*/
551 alloc_func(data, pnum_begin, pnum,
552 map_count, nodeid_begin);
553 /* new start, update count etc*/
554 nodeid_begin = nodeid;
559 alloc_func(data, pnum_begin, NR_MEM_SECTIONS,
560 map_count, nodeid_begin);
564 * Allocate the accumulated non-linear sections, allocate a mem_map
565 * for each and record the physical to section mapping.
567 void __init sparse_init(void)
571 unsigned long *usemap;
572 unsigned long **usemap_map;
574 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
576 struct page **map_map;
579 /* see include/linux/mmzone.h 'struct mem_section' definition */
580 BUILD_BUG_ON(!is_power_of_2(sizeof(struct mem_section)));
582 /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
583 set_pageblock_order();
586 * map is using big page (aka 2M in x86 64 bit)
587 * usemap is less one page (aka 24 bytes)
588 * so alloc 2M (with 2M align) and 24 bytes in turn will
589 * make next 2M slip to one more 2M later.
590 * then in big system, the memory will have a lot of holes...
591 * here try to allocate 2M pages continuously.
593 * powerpc need to call sparse_init_one_section right after each
594 * sparse_early_mem_map_alloc, so allocate usemap_map at first.
596 size = sizeof(unsigned long *) * NR_MEM_SECTIONS;
597 usemap_map = memblock_virt_alloc(size, 0);
599 panic("can not allocate usemap_map\n");
600 alloc_usemap_and_memmap(sparse_early_usemaps_alloc_node,
603 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
604 size2 = sizeof(struct page *) * NR_MEM_SECTIONS;
605 map_map = memblock_virt_alloc(size2, 0);
607 panic("can not allocate map_map\n");
608 alloc_usemap_and_memmap(sparse_early_mem_maps_alloc_node,
612 for_each_present_section_nr(0, pnum) {
613 usemap = usemap_map[pnum];
617 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
620 map = sparse_early_mem_map_alloc(pnum);
625 sparse_init_one_section(__nr_to_section(pnum), pnum, map,
629 vmemmap_populate_print_last();
631 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
632 memblock_free_early(__pa(map_map), size2);
634 memblock_free_early(__pa(usemap_map), size);
637 #ifdef CONFIG_MEMORY_HOTPLUG
639 /* Mark all memory sections within the pfn range as online */
640 void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
644 for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
645 unsigned long section_nr = pfn_to_section_nr(pfn);
646 struct mem_section *ms;
648 /* onlining code should never touch invalid ranges */
649 if (WARN_ON(!valid_section_nr(section_nr)))
652 ms = __nr_to_section(section_nr);
653 ms->section_mem_map |= SECTION_IS_ONLINE;
657 #ifdef CONFIG_MEMORY_HOTREMOVE
658 /* Mark all memory sections within the pfn range as online */
659 void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
663 for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
664 unsigned long section_nr = pfn_to_section_nr(start_pfn);
665 struct mem_section *ms;
668 * TODO this needs some double checking. Offlining code makes
669 * sure to check pfn_valid but those checks might be just bogus
671 if (WARN_ON(!valid_section_nr(section_nr)))
674 ms = __nr_to_section(section_nr);
675 ms->section_mem_map &= ~SECTION_IS_ONLINE;
680 #ifdef CONFIG_SPARSEMEM_VMEMMAP
681 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid)
683 /* This will make the necessary allocations eventually. */
684 return sparse_mem_map_populate(pnum, nid);
686 static void __kfree_section_memmap(struct page *memmap)
688 unsigned long start = (unsigned long)memmap;
689 unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
691 vmemmap_free(start, end);
693 #ifdef CONFIG_MEMORY_HOTREMOVE
694 static void free_map_bootmem(struct page *memmap)
696 unsigned long start = (unsigned long)memmap;
697 unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
699 vmemmap_free(start, end);
701 #endif /* CONFIG_MEMORY_HOTREMOVE */
703 static struct page *__kmalloc_section_memmap(void)
705 struct page *page, *ret;
706 unsigned long memmap_size = sizeof(struct page) * PAGES_PER_SECTION;
708 page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
712 ret = vmalloc(memmap_size);
718 ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
724 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid)
726 return __kmalloc_section_memmap();
729 static void __kfree_section_memmap(struct page *memmap)
731 if (is_vmalloc_addr(memmap))
734 free_pages((unsigned long)memmap,
735 get_order(sizeof(struct page) * PAGES_PER_SECTION));
738 #ifdef CONFIG_MEMORY_HOTREMOVE
739 static void free_map_bootmem(struct page *memmap)
741 unsigned long maps_section_nr, removing_section_nr, i;
742 unsigned long magic, nr_pages;
743 struct page *page = virt_to_page(memmap);
745 nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
748 for (i = 0; i < nr_pages; i++, page++) {
749 magic = (unsigned long) page->freelist;
751 BUG_ON(magic == NODE_INFO);
753 maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
754 removing_section_nr = page_private(page);
757 * When this function is called, the removing section is
758 * logical offlined state. This means all pages are isolated
759 * from page allocator. If removing section's memmap is placed
760 * on the same section, it must not be freed.
761 * If it is freed, page allocator may allocate it which will
762 * be removed physically soon.
764 if (maps_section_nr != removing_section_nr)
765 put_page_bootmem(page);
768 #endif /* CONFIG_MEMORY_HOTREMOVE */
769 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
772 * returns the number of sections whose mem_maps were properly
773 * set. If this is <=0, then that means that the passed-in
774 * map was not consumed and must be freed.
776 int __meminit sparse_add_one_section(struct pglist_data *pgdat, unsigned long start_pfn)
778 unsigned long section_nr = pfn_to_section_nr(start_pfn);
779 struct mem_section *ms;
781 unsigned long *usemap;
786 * no locking for this, because it does its own
787 * plus, it does a kmalloc
789 ret = sparse_index_init(section_nr, pgdat->node_id);
790 if (ret < 0 && ret != -EEXIST)
792 memmap = kmalloc_section_memmap(section_nr, pgdat->node_id);
795 usemap = __kmalloc_section_usemap();
797 __kfree_section_memmap(memmap);
801 pgdat_resize_lock(pgdat, &flags);
803 ms = __pfn_to_section(start_pfn);
804 if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
809 memset(memmap, 0, sizeof(struct page) * PAGES_PER_SECTION);
811 section_mark_present(ms);
813 ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
816 pgdat_resize_unlock(pgdat, &flags);
819 __kfree_section_memmap(memmap);
824 #ifdef CONFIG_MEMORY_HOTREMOVE
825 #ifdef CONFIG_MEMORY_FAILURE
826 static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
833 for (i = 0; i < nr_pages; i++) {
834 if (PageHWPoison(&memmap[i])) {
835 atomic_long_sub(1, &num_poisoned_pages);
836 ClearPageHWPoison(&memmap[i]);
841 static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
846 static void free_section_usemap(struct page *memmap, unsigned long *usemap)
848 struct page *usemap_page;
853 usemap_page = virt_to_page(usemap);
855 * Check to see if allocation came from hot-plug-add
857 if (PageSlab(usemap_page) || PageCompound(usemap_page)) {
860 __kfree_section_memmap(memmap);
865 * The usemap came from bootmem. This is packed with other usemaps
866 * on the section which has pgdat at boot time. Just keep it as is now.
870 free_map_bootmem(memmap);
873 void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
874 unsigned long map_offset)
876 struct page *memmap = NULL;
877 unsigned long *usemap = NULL, flags;
878 struct pglist_data *pgdat = zone->zone_pgdat;
880 pgdat_resize_lock(pgdat, &flags);
881 if (ms->section_mem_map) {
882 usemap = ms->pageblock_flags;
883 memmap = sparse_decode_mem_map(ms->section_mem_map,
885 ms->section_mem_map = 0;
886 ms->pageblock_flags = NULL;
888 pgdat_resize_unlock(pgdat, &flags);
890 clear_hwpoisoned_pages(memmap + map_offset,
891 PAGES_PER_SECTION - map_offset);
892 free_section_usemap(memmap, usemap);
894 #endif /* CONFIG_MEMORY_HOTREMOVE */
895 #endif /* CONFIG_MEMORY_HOTPLUG */