Merge branch 'for-4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu
[platform/kernel/linux-rpi.git] / mm / sparse.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * sparse memory mappings.
4  */
5 #include <linux/mm.h>
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>
14
15 #include "internal.h"
16 #include <asm/dma.h>
17 #include <asm/pgalloc.h>
18 #include <asm/pgtable.h>
19
20 /*
21  * Permanent SPARSEMEM data:
22  *
23  * 1) mem_section       - memory sections, mem_map's for valid memory
24  */
25 #ifdef CONFIG_SPARSEMEM_EXTREME
26 struct mem_section **mem_section;
27 #else
28 struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
29         ____cacheline_internodealigned_in_smp;
30 #endif
31 EXPORT_SYMBOL(mem_section);
32
33 #ifdef NODE_NOT_IN_PAGE_FLAGS
34 /*
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.
38  */
39 #if MAX_NUMNODES <= 256
40 static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
41 #else
42 static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
43 #endif
44
45 int page_to_nid(const struct page *page)
46 {
47         return section_to_node_table[page_to_section(page)];
48 }
49 EXPORT_SYMBOL(page_to_nid);
50
51 static void set_section_nid(unsigned long section_nr, int nid)
52 {
53         section_to_node_table[section_nr] = nid;
54 }
55 #else /* !NODE_NOT_IN_PAGE_FLAGS */
56 static inline void set_section_nid(unsigned long section_nr, int nid)
57 {
58 }
59 #endif
60
61 #ifdef CONFIG_SPARSEMEM_EXTREME
62 static noinline struct mem_section __ref *sparse_index_alloc(int nid)
63 {
64         struct mem_section *section = NULL;
65         unsigned long array_size = SECTIONS_PER_ROOT *
66                                    sizeof(struct mem_section);
67
68         if (slab_is_available())
69                 section = kzalloc_node(array_size, GFP_KERNEL, nid);
70         else
71                 section = memblock_alloc_node(array_size, SMP_CACHE_BYTES,
72                                               nid);
73
74         return section;
75 }
76
77 static int __meminit sparse_index_init(unsigned long section_nr, int nid)
78 {
79         unsigned long root = SECTION_NR_TO_ROOT(section_nr);
80         struct mem_section *section;
81
82         if (mem_section[root])
83                 return -EEXIST;
84
85         section = sparse_index_alloc(nid);
86         if (!section)
87                 return -ENOMEM;
88
89         mem_section[root] = section;
90
91         return 0;
92 }
93 #else /* !SPARSEMEM_EXTREME */
94 static inline int sparse_index_init(unsigned long section_nr, int nid)
95 {
96         return 0;
97 }
98 #endif
99
100 #ifdef CONFIG_SPARSEMEM_EXTREME
101 int __section_nr(struct mem_section* ms)
102 {
103         unsigned long root_nr;
104         struct mem_section *root = NULL;
105
106         for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
107                 root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
108                 if (!root)
109                         continue;
110
111                 if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
112                      break;
113         }
114
115         VM_BUG_ON(!root);
116
117         return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
118 }
119 #else
120 int __section_nr(struct mem_section* ms)
121 {
122         return (int)(ms - mem_section[0]);
123 }
124 #endif
125
126 /*
127  * During early boot, before section_mem_map is used for an actual
128  * mem_map, we use section_mem_map to store the section's NUMA
129  * node.  This keeps us from having to use another data structure.  The
130  * node information is cleared just before we store the real mem_map.
131  */
132 static inline unsigned long sparse_encode_early_nid(int nid)
133 {
134         return (nid << SECTION_NID_SHIFT);
135 }
136
137 static inline int sparse_early_nid(struct mem_section *section)
138 {
139         return (section->section_mem_map >> SECTION_NID_SHIFT);
140 }
141
142 /* Validate the physical addressing limitations of the model */
143 void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
144                                                 unsigned long *end_pfn)
145 {
146         unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
147
148         /*
149          * Sanity checks - do not allow an architecture to pass
150          * in larger pfns than the maximum scope of sparsemem:
151          */
152         if (*start_pfn > max_sparsemem_pfn) {
153                 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
154                         "Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
155                         *start_pfn, *end_pfn, max_sparsemem_pfn);
156                 WARN_ON_ONCE(1);
157                 *start_pfn = max_sparsemem_pfn;
158                 *end_pfn = max_sparsemem_pfn;
159         } else if (*end_pfn > max_sparsemem_pfn) {
160                 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
161                         "End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
162                         *start_pfn, *end_pfn, max_sparsemem_pfn);
163                 WARN_ON_ONCE(1);
164                 *end_pfn = max_sparsemem_pfn;
165         }
166 }
167
168 /*
169  * There are a number of times that we loop over NR_MEM_SECTIONS,
170  * looking for section_present() on each.  But, when we have very
171  * large physical address spaces, NR_MEM_SECTIONS can also be
172  * very large which makes the loops quite long.
173  *
174  * Keeping track of this gives us an easy way to break out of
175  * those loops early.
176  */
177 int __highest_present_section_nr;
178 static void section_mark_present(struct mem_section *ms)
179 {
180         int section_nr = __section_nr(ms);
181
182         if (section_nr > __highest_present_section_nr)
183                 __highest_present_section_nr = section_nr;
184
185         ms->section_mem_map |= SECTION_MARKED_PRESENT;
186 }
187
188 static inline int next_present_section_nr(int section_nr)
189 {
190         do {
191                 section_nr++;
192                 if (present_section_nr(section_nr))
193                         return section_nr;
194         } while ((section_nr <= __highest_present_section_nr));
195
196         return -1;
197 }
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 <= __highest_present_section_nr));    \
202              section_nr = next_present_section_nr(section_nr))
203
204 static inline unsigned long first_present_section_nr(void)
205 {
206         return next_present_section_nr(-1);
207 }
208
209 /* Record a memory area against a node. */
210 void __init memory_present(int nid, unsigned long start, unsigned long end)
211 {
212         unsigned long pfn;
213
214 #ifdef CONFIG_SPARSEMEM_EXTREME
215         if (unlikely(!mem_section)) {
216                 unsigned long size, align;
217
218                 size = sizeof(struct mem_section*) * NR_SECTION_ROOTS;
219                 align = 1 << (INTERNODE_CACHE_SHIFT);
220                 mem_section = memblock_alloc(size, align);
221         }
222 #endif
223
224         start &= PAGE_SECTION_MASK;
225         mminit_validate_memmodel_limits(&start, &end);
226         for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
227                 unsigned long section = pfn_to_section_nr(pfn);
228                 struct mem_section *ms;
229
230                 sparse_index_init(section, nid);
231                 set_section_nid(section, nid);
232
233                 ms = __nr_to_section(section);
234                 if (!ms->section_mem_map) {
235                         ms->section_mem_map = sparse_encode_early_nid(nid) |
236                                                         SECTION_IS_ONLINE;
237                         section_mark_present(ms);
238                 }
239         }
240 }
241
242 /*
243  * Subtle, we encode the real pfn into the mem_map such that
244  * the identity pfn - section_mem_map will return the actual
245  * physical page frame number.
246  */
247 static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
248 {
249         unsigned long coded_mem_map =
250                 (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
251         BUILD_BUG_ON(SECTION_MAP_LAST_BIT > (1UL<<PFN_SECTION_SHIFT));
252         BUG_ON(coded_mem_map & ~SECTION_MAP_MASK);
253         return coded_mem_map;
254 }
255
256 /*
257  * Decode mem_map from the coded memmap
258  */
259 struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
260 {
261         /* mask off the extra low bits of information */
262         coded_mem_map &= SECTION_MAP_MASK;
263         return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
264 }
265
266 static void __meminit sparse_init_one_section(struct mem_section *ms,
267                 unsigned long pnum, struct page *mem_map,
268                 unsigned long *pageblock_bitmap)
269 {
270         ms->section_mem_map &= ~SECTION_MAP_MASK;
271         ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
272                                                         SECTION_HAS_MEM_MAP;
273         ms->pageblock_flags = pageblock_bitmap;
274 }
275
276 unsigned long usemap_size(void)
277 {
278         return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
279 }
280
281 #ifdef CONFIG_MEMORY_HOTPLUG
282 static unsigned long *__kmalloc_section_usemap(void)
283 {
284         return kmalloc(usemap_size(), GFP_KERNEL);
285 }
286 #endif /* CONFIG_MEMORY_HOTPLUG */
287
288 #ifdef CONFIG_MEMORY_HOTREMOVE
289 static unsigned long * __init
290 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
291                                          unsigned long size)
292 {
293         unsigned long goal, limit;
294         unsigned long *p;
295         int nid;
296         /*
297          * A page may contain usemaps for other sections preventing the
298          * page being freed and making a section unremovable while
299          * other sections referencing the usemap remain active. Similarly,
300          * a pgdat can prevent a section being removed. If section A
301          * contains a pgdat and section B contains the usemap, both
302          * sections become inter-dependent. This allocates usemaps
303          * from the same section as the pgdat where possible to avoid
304          * this problem.
305          */
306         goal = __pa(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
307         limit = goal + (1UL << PA_SECTION_SHIFT);
308         nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
309 again:
310         p = memblock_alloc_try_nid_nopanic(size,
311                                                 SMP_CACHE_BYTES, goal, limit,
312                                                 nid);
313         if (!p && limit) {
314                 limit = 0;
315                 goto again;
316         }
317         return p;
318 }
319
320 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
321 {
322         unsigned long usemap_snr, pgdat_snr;
323         static unsigned long old_usemap_snr;
324         static unsigned long old_pgdat_snr;
325         struct pglist_data *pgdat = NODE_DATA(nid);
326         int usemap_nid;
327
328         /* First call */
329         if (!old_usemap_snr) {
330                 old_usemap_snr = NR_MEM_SECTIONS;
331                 old_pgdat_snr = NR_MEM_SECTIONS;
332         }
333
334         usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
335         pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
336         if (usemap_snr == pgdat_snr)
337                 return;
338
339         if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
340                 /* skip redundant message */
341                 return;
342
343         old_usemap_snr = usemap_snr;
344         old_pgdat_snr = pgdat_snr;
345
346         usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
347         if (usemap_nid != nid) {
348                 pr_info("node %d must be removed before remove section %ld\n",
349                         nid, usemap_snr);
350                 return;
351         }
352         /*
353          * There is a circular dependency.
354          * Some platforms allow un-removable section because they will just
355          * gather other removable sections for dynamic partitioning.
356          * Just notify un-removable section's number here.
357          */
358         pr_info("Section %ld and %ld (node %d) have a circular dependency on usemap and pgdat allocations\n",
359                 usemap_snr, pgdat_snr, nid);
360 }
361 #else
362 static unsigned long * __init
363 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
364                                          unsigned long size)
365 {
366         return memblock_alloc_node_nopanic(size, pgdat->node_id);
367 }
368
369 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
370 {
371 }
372 #endif /* CONFIG_MEMORY_HOTREMOVE */
373
374 #ifdef CONFIG_SPARSEMEM_VMEMMAP
375 static unsigned long __init section_map_size(void)
376 {
377         return ALIGN(sizeof(struct page) * PAGES_PER_SECTION, PMD_SIZE);
378 }
379
380 #else
381 static unsigned long __init section_map_size(void)
382 {
383         return PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
384 }
385
386 struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid,
387                 struct vmem_altmap *altmap)
388 {
389         unsigned long size = section_map_size();
390         struct page *map = sparse_buffer_alloc(size);
391
392         if (map)
393                 return map;
394
395         map = memblock_alloc_try_nid(size,
396                                           PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
397                                           MEMBLOCK_ALLOC_ACCESSIBLE, nid);
398         return map;
399 }
400 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
401
402 static void *sparsemap_buf __meminitdata;
403 static void *sparsemap_buf_end __meminitdata;
404
405 static void __init sparse_buffer_init(unsigned long size, int nid)
406 {
407         WARN_ON(sparsemap_buf); /* forgot to call sparse_buffer_fini()? */
408         sparsemap_buf =
409                 memblock_alloc_try_nid_raw(size, PAGE_SIZE,
410                                                 __pa(MAX_DMA_ADDRESS),
411                                                 MEMBLOCK_ALLOC_ACCESSIBLE, nid);
412         sparsemap_buf_end = sparsemap_buf + size;
413 }
414
415 static void __init sparse_buffer_fini(void)
416 {
417         unsigned long size = sparsemap_buf_end - sparsemap_buf;
418
419         if (sparsemap_buf && size > 0)
420                 memblock_free_early(__pa(sparsemap_buf), size);
421         sparsemap_buf = NULL;
422 }
423
424 void * __meminit sparse_buffer_alloc(unsigned long size)
425 {
426         void *ptr = NULL;
427
428         if (sparsemap_buf) {
429                 ptr = PTR_ALIGN(sparsemap_buf, size);
430                 if (ptr + size > sparsemap_buf_end)
431                         ptr = NULL;
432                 else
433                         sparsemap_buf = ptr + size;
434         }
435         return ptr;
436 }
437
438 void __weak __meminit vmemmap_populate_print_last(void)
439 {
440 }
441
442 /*
443  * Initialize sparse on a specific node. The node spans [pnum_begin, pnum_end)
444  * And number of present sections in this node is map_count.
445  */
446 static void __init sparse_init_nid(int nid, unsigned long pnum_begin,
447                                    unsigned long pnum_end,
448                                    unsigned long map_count)
449 {
450         unsigned long pnum, usemap_longs, *usemap;
451         struct page *map;
452
453         usemap_longs = BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS);
454         usemap = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nid),
455                                                           usemap_size() *
456                                                           map_count);
457         if (!usemap) {
458                 pr_err("%s: node[%d] usemap allocation failed", __func__, nid);
459                 goto failed;
460         }
461         sparse_buffer_init(map_count * section_map_size(), nid);
462         for_each_present_section_nr(pnum_begin, pnum) {
463                 if (pnum >= pnum_end)
464                         break;
465
466                 map = sparse_mem_map_populate(pnum, nid, NULL);
467                 if (!map) {
468                         pr_err("%s: node[%d] memory map backing failed. Some memory will not be available.",
469                                __func__, nid);
470                         pnum_begin = pnum;
471                         goto failed;
472                 }
473                 check_usemap_section_nr(nid, usemap);
474                 sparse_init_one_section(__nr_to_section(pnum), pnum, map, usemap);
475                 usemap += usemap_longs;
476         }
477         sparse_buffer_fini();
478         return;
479 failed:
480         /* We failed to allocate, mark all the following pnums as not present */
481         for_each_present_section_nr(pnum_begin, pnum) {
482                 struct mem_section *ms;
483
484                 if (pnum >= pnum_end)
485                         break;
486                 ms = __nr_to_section(pnum);
487                 ms->section_mem_map = 0;
488         }
489 }
490
491 /*
492  * Allocate the accumulated non-linear sections, allocate a mem_map
493  * for each and record the physical to section mapping.
494  */
495 void __init sparse_init(void)
496 {
497         unsigned long pnum_begin = first_present_section_nr();
498         int nid_begin = sparse_early_nid(__nr_to_section(pnum_begin));
499         unsigned long pnum_end, map_count = 1;
500
501         /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
502         set_pageblock_order();
503
504         for_each_present_section_nr(pnum_begin + 1, pnum_end) {
505                 int nid = sparse_early_nid(__nr_to_section(pnum_end));
506
507                 if (nid == nid_begin) {
508                         map_count++;
509                         continue;
510                 }
511                 /* Init node with sections in range [pnum_begin, pnum_end) */
512                 sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
513                 nid_begin = nid;
514                 pnum_begin = pnum_end;
515                 map_count = 1;
516         }
517         /* cover the last node */
518         sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
519         vmemmap_populate_print_last();
520 }
521
522 #ifdef CONFIG_MEMORY_HOTPLUG
523
524 /* Mark all memory sections within the pfn range as online */
525 void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
526 {
527         unsigned long pfn;
528
529         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
530                 unsigned long section_nr = pfn_to_section_nr(pfn);
531                 struct mem_section *ms;
532
533                 /* onlining code should never touch invalid ranges */
534                 if (WARN_ON(!valid_section_nr(section_nr)))
535                         continue;
536
537                 ms = __nr_to_section(section_nr);
538                 ms->section_mem_map |= SECTION_IS_ONLINE;
539         }
540 }
541
542 #ifdef CONFIG_MEMORY_HOTREMOVE
543 /* Mark all memory sections within the pfn range as online */
544 void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
545 {
546         unsigned long pfn;
547
548         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
549                 unsigned long section_nr = pfn_to_section_nr(pfn);
550                 struct mem_section *ms;
551
552                 /*
553                  * TODO this needs some double checking. Offlining code makes
554                  * sure to check pfn_valid but those checks might be just bogus
555                  */
556                 if (WARN_ON(!valid_section_nr(section_nr)))
557                         continue;
558
559                 ms = __nr_to_section(section_nr);
560                 ms->section_mem_map &= ~SECTION_IS_ONLINE;
561         }
562 }
563 #endif
564
565 #ifdef CONFIG_SPARSEMEM_VMEMMAP
566 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
567                 struct vmem_altmap *altmap)
568 {
569         /* This will make the necessary allocations eventually. */
570         return sparse_mem_map_populate(pnum, nid, altmap);
571 }
572 static void __kfree_section_memmap(struct page *memmap,
573                 struct vmem_altmap *altmap)
574 {
575         unsigned long start = (unsigned long)memmap;
576         unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
577
578         vmemmap_free(start, end, altmap);
579 }
580 #ifdef CONFIG_MEMORY_HOTREMOVE
581 static void free_map_bootmem(struct page *memmap)
582 {
583         unsigned long start = (unsigned long)memmap;
584         unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
585
586         vmemmap_free(start, end, NULL);
587 }
588 #endif /* CONFIG_MEMORY_HOTREMOVE */
589 #else
590 static struct page *__kmalloc_section_memmap(void)
591 {
592         struct page *page, *ret;
593         unsigned long memmap_size = sizeof(struct page) * PAGES_PER_SECTION;
594
595         page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
596         if (page)
597                 goto got_map_page;
598
599         ret = vmalloc(memmap_size);
600         if (ret)
601                 goto got_map_ptr;
602
603         return NULL;
604 got_map_page:
605         ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
606 got_map_ptr:
607
608         return ret;
609 }
610
611 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
612                 struct vmem_altmap *altmap)
613 {
614         return __kmalloc_section_memmap();
615 }
616
617 static void __kfree_section_memmap(struct page *memmap,
618                 struct vmem_altmap *altmap)
619 {
620         if (is_vmalloc_addr(memmap))
621                 vfree(memmap);
622         else
623                 free_pages((unsigned long)memmap,
624                            get_order(sizeof(struct page) * PAGES_PER_SECTION));
625 }
626
627 #ifdef CONFIG_MEMORY_HOTREMOVE
628 static void free_map_bootmem(struct page *memmap)
629 {
630         unsigned long maps_section_nr, removing_section_nr, i;
631         unsigned long magic, nr_pages;
632         struct page *page = virt_to_page(memmap);
633
634         nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
635                 >> PAGE_SHIFT;
636
637         for (i = 0; i < nr_pages; i++, page++) {
638                 magic = (unsigned long) page->freelist;
639
640                 BUG_ON(magic == NODE_INFO);
641
642                 maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
643                 removing_section_nr = page_private(page);
644
645                 /*
646                  * When this function is called, the removing section is
647                  * logical offlined state. This means all pages are isolated
648                  * from page allocator. If removing section's memmap is placed
649                  * on the same section, it must not be freed.
650                  * If it is freed, page allocator may allocate it which will
651                  * be removed physically soon.
652                  */
653                 if (maps_section_nr != removing_section_nr)
654                         put_page_bootmem(page);
655         }
656 }
657 #endif /* CONFIG_MEMORY_HOTREMOVE */
658 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
659
660 /*
661  * returns the number of sections whose mem_maps were properly
662  * set.  If this is <=0, then that means that the passed-in
663  * map was not consumed and must be freed.
664  */
665 int __meminit sparse_add_one_section(struct pglist_data *pgdat,
666                 unsigned long start_pfn, struct vmem_altmap *altmap)
667 {
668         unsigned long section_nr = pfn_to_section_nr(start_pfn);
669         struct mem_section *ms;
670         struct page *memmap;
671         unsigned long *usemap;
672         unsigned long flags;
673         int ret;
674
675         /*
676          * no locking for this, because it does its own
677          * plus, it does a kmalloc
678          */
679         ret = sparse_index_init(section_nr, pgdat->node_id);
680         if (ret < 0 && ret != -EEXIST)
681                 return ret;
682         ret = 0;
683         memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, altmap);
684         if (!memmap)
685                 return -ENOMEM;
686         usemap = __kmalloc_section_usemap();
687         if (!usemap) {
688                 __kfree_section_memmap(memmap, altmap);
689                 return -ENOMEM;
690         }
691
692         pgdat_resize_lock(pgdat, &flags);
693
694         ms = __pfn_to_section(start_pfn);
695         if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
696                 ret = -EEXIST;
697                 goto out;
698         }
699
700         /*
701          * Poison uninitialized struct pages in order to catch invalid flags
702          * combinations.
703          */
704         page_init_poison(memmap, sizeof(struct page) * PAGES_PER_SECTION);
705
706         section_mark_present(ms);
707         sparse_init_one_section(ms, section_nr, memmap, usemap);
708
709 out:
710         pgdat_resize_unlock(pgdat, &flags);
711         if (ret < 0) {
712                 kfree(usemap);
713                 __kfree_section_memmap(memmap, altmap);
714         }
715         return ret;
716 }
717
718 #ifdef CONFIG_MEMORY_HOTREMOVE
719 #ifdef CONFIG_MEMORY_FAILURE
720 static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
721 {
722         int i;
723
724         if (!memmap)
725                 return;
726
727         for (i = 0; i < nr_pages; i++) {
728                 if (PageHWPoison(&memmap[i])) {
729                         atomic_long_sub(1, &num_poisoned_pages);
730                         ClearPageHWPoison(&memmap[i]);
731                 }
732         }
733 }
734 #else
735 static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
736 {
737 }
738 #endif
739
740 static void free_section_usemap(struct page *memmap, unsigned long *usemap,
741                 struct vmem_altmap *altmap)
742 {
743         struct page *usemap_page;
744
745         if (!usemap)
746                 return;
747
748         usemap_page = virt_to_page(usemap);
749         /*
750          * Check to see if allocation came from hot-plug-add
751          */
752         if (PageSlab(usemap_page) || PageCompound(usemap_page)) {
753                 kfree(usemap);
754                 if (memmap)
755                         __kfree_section_memmap(memmap, altmap);
756                 return;
757         }
758
759         /*
760          * The usemap came from bootmem. This is packed with other usemaps
761          * on the section which has pgdat at boot time. Just keep it as is now.
762          */
763
764         if (memmap)
765                 free_map_bootmem(memmap);
766 }
767
768 void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
769                 unsigned long map_offset, struct vmem_altmap *altmap)
770 {
771         struct page *memmap = NULL;
772         unsigned long *usemap = NULL, flags;
773         struct pglist_data *pgdat = zone->zone_pgdat;
774
775         pgdat_resize_lock(pgdat, &flags);
776         if (ms->section_mem_map) {
777                 usemap = ms->pageblock_flags;
778                 memmap = sparse_decode_mem_map(ms->section_mem_map,
779                                                 __section_nr(ms));
780                 ms->section_mem_map = 0;
781                 ms->pageblock_flags = NULL;
782         }
783         pgdat_resize_unlock(pgdat, &flags);
784
785         clear_hwpoisoned_pages(memmap + map_offset,
786                         PAGES_PER_SECTION - map_offset);
787         free_section_usemap(memmap, usemap, altmap);
788 }
789 #endif /* CONFIG_MEMORY_HOTREMOVE */
790 #endif /* CONFIG_MEMORY_HOTPLUG */