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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 #include <linux/swap.h>
15 #include <linux/swapops.h>
16 #include <linux/bootmem_info.h>
17
18 #include "internal.h"
19 #include <asm/dma.h>
20
21 /*
22 * Permanent SPARSEMEM data:
23 *
24 * 1) mem_section - memory sections, mem_map's for valid memory
25 */
26 #ifdef CONFIG_SPARSEMEM_EXTREME
27 struct mem_section **mem_section;
28 #else
29 struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
30 ____cacheline_internodealigned_in_smp;
31 #endif
32 EXPORT_SYMBOL(mem_section);
33
34 #ifdef NODE_NOT_IN_PAGE_FLAGS
35 /*
36 * If we did not store the node number in the page then we have to
37 * do a lookup in the section_to_node_table in order to find which
38 * node the page belongs to.
39 */
40 #if MAX_NUMNODES <= 256
41 static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
42 #else
43 static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
44 #endif
45
46 int page_to_nid(const struct page *page)
47 {
48 return section_to_node_table[page_to_section(page)];
49 }
50 EXPORT_SYMBOL(page_to_nid);
51
52 static void set_section_nid(unsigned long section_nr, int nid)
53 {
54 section_to_node_table[section_nr] = nid;
55 }
56 #else /* !NODE_NOT_IN_PAGE_FLAGS */
57 static inline void set_section_nid(unsigned long section_nr, int nid)
58 {
59 }
60 #endif
61
62 #ifdef CONFIG_SPARSEMEM_EXTREME
63 static noinline struct mem_section __ref *sparse_index_alloc(int nid)
64 {
65 struct mem_section *section = NULL;
66 unsigned long array_size = SECTIONS_PER_ROOT *
67 sizeof(struct mem_section);
68
69 if (slab_is_available()) {
70 section = kzalloc_node(array_size, GFP_KERNEL, nid);
71 } else {
72 section = memblock_alloc_node(array_size, SMP_CACHE_BYTES,
73 nid);
74 if (!section)
75 panic("%s: Failed to allocate %lu bytes nid=%d\n",
76 __func__, array_size, nid);
77 }
78
79 return section;
80 }
81
82 static int __meminit sparse_index_init(unsigned long section_nr, int nid)
83 {
84 unsigned long root = SECTION_NR_TO_ROOT(section_nr);
85 struct mem_section *section;
86
87 /*
88 * An existing section is possible in the sub-section hotplug
89 * case. First hot-add instantiates, follow-on hot-add reuses
90 * the existing section.
91 *
92 * The mem_hotplug_lock resolves the apparent race below.
93 */
94 if (mem_section[root])
95 return 0;
96
97 section = sparse_index_alloc(nid);
98 if (!section)
99 return -ENOMEM;
100
101 mem_section[root] = section;
102
103 return 0;
104 }
105 #else /* !SPARSEMEM_EXTREME */
106 static inline int sparse_index_init(unsigned long section_nr, int nid)
107 {
108 return 0;
109 }
110 #endif
111
112 /*
113 * During early boot, before section_mem_map is used for an actual
114 * mem_map, we use section_mem_map to store the section's NUMA
115 * node. This keeps us from having to use another data structure. The
116 * node information is cleared just before we store the real mem_map.
117 */
118 static inline unsigned long sparse_encode_early_nid(int nid)
119 {
120 return ((unsigned long)nid << SECTION_NID_SHIFT);
121 }
122
123 static inline int sparse_early_nid(struct mem_section *section)
124 {
125 return (section->section_mem_map >> SECTION_NID_SHIFT);
126 }
127
128 /* Validate the physical addressing limitations of the model */
129 void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
130 unsigned long *end_pfn)
131 {
132 unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
133
134 /*
135 * Sanity checks - do not allow an architecture to pass
136 * in larger pfns than the maximum scope of sparsemem:
137 */
138 if (*start_pfn > max_sparsemem_pfn) {
139 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
140 "Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
141 *start_pfn, *end_pfn, max_sparsemem_pfn);
142 WARN_ON_ONCE(1);
143 *start_pfn = max_sparsemem_pfn;
144 *end_pfn = max_sparsemem_pfn;
145 } else if (*end_pfn > max_sparsemem_pfn) {
146 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
147 "End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
148 *start_pfn, *end_pfn, max_sparsemem_pfn);
149 WARN_ON_ONCE(1);
150 *end_pfn = max_sparsemem_pfn;
151 }
152 }
153
154 /*
155 * There are a number of times that we loop over NR_MEM_SECTIONS,
156 * looking for section_present() on each. But, when we have very
157 * large physical address spaces, NR_MEM_SECTIONS can also be
158 * very large which makes the loops quite long.
159 *
160 * Keeping track of this gives us an easy way to break out of
161 * those loops early.
162 */
163 unsigned long __highest_present_section_nr;
164 static void __section_mark_present(struct mem_section *ms,
165 unsigned long section_nr)
166 {
167 if (section_nr > __highest_present_section_nr)
168 __highest_present_section_nr = section_nr;
169
170 ms->section_mem_map |= SECTION_MARKED_PRESENT;
171 }
172
173 #define for_each_present_section_nr(start, section_nr) \
174 for (section_nr = next_present_section_nr(start-1); \
175 ((section_nr != -1) && \
176 (section_nr <= __highest_present_section_nr)); \
177 section_nr = next_present_section_nr(section_nr))
178
179 static inline unsigned long first_present_section_nr(void)
180 {
181 return next_present_section_nr(-1);
182 }
183
184 #ifdef CONFIG_SPARSEMEM_VMEMMAP
185 static void subsection_mask_set(unsigned long *map, unsigned long pfn,
186 unsigned long nr_pages)
187 {
188 int idx = subsection_map_index(pfn);
189 int end = subsection_map_index(pfn + nr_pages - 1);
190
191 bitmap_set(map, idx, end - idx + 1);
192 }
193
194 void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
195 {
196 int end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
197 unsigned long nr, start_sec = pfn_to_section_nr(pfn);
198
199 if (!nr_pages)
200 return;
201
202 for (nr = start_sec; nr <= end_sec; nr++) {
203 struct mem_section *ms;
204 unsigned long pfns;
205
206 pfns = min(nr_pages, PAGES_PER_SECTION
207 - (pfn & ~PAGE_SECTION_MASK));
208 ms = __nr_to_section(nr);
209 subsection_mask_set(ms->usage->subsection_map, pfn, pfns);
210
211 pr_debug("%s: sec: %lu pfns: %lu set(%d, %d)\n", __func__, nr,
212 pfns, subsection_map_index(pfn),
213 subsection_map_index(pfn + pfns - 1));
214
215 pfn += pfns;
216 nr_pages -= pfns;
217 }
218 }
219 #else
220 void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
221 {
222 }
223 #endif
224
225 /* Record a memory area against a node. */
226 static void __init memory_present(int nid, unsigned long start, unsigned long end)
227 {
228 unsigned long pfn;
229
230 #ifdef CONFIG_SPARSEMEM_EXTREME
231 if (unlikely(!mem_section)) {
232 unsigned long size, align;
233
234 size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
235 align = 1 << (INTERNODE_CACHE_SHIFT);
236 mem_section = memblock_alloc(size, align);
237 if (!mem_section)
238 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
239 __func__, size, align);
240 }
241 #endif
242
243 start &= PAGE_SECTION_MASK;
244 mminit_validate_memmodel_limits(&start, &end);
245 for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
246 unsigned long section = pfn_to_section_nr(pfn);
247 struct mem_section *ms;
248
249 sparse_index_init(section, nid);
250 set_section_nid(section, nid);
251
252 ms = __nr_to_section(section);
253 if (!ms->section_mem_map) {
254 ms->section_mem_map = sparse_encode_early_nid(nid) |
255 SECTION_IS_ONLINE;
256 __section_mark_present(ms, section);
257 }
258 }
259 }
260
261 /*
262 * Mark all memblocks as present using memory_present().
263 * This is a convenience function that is useful to mark all of the systems
264 * memory as present during initialization.
265 */
266 static void __init memblocks_present(void)
267 {
268 unsigned long start, end;
269 int i, nid;
270
271 for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid)
272 memory_present(nid, start, end);
273 }
274
275 /*
276 * Subtle, we encode the real pfn into the mem_map such that
277 * the identity pfn - section_mem_map will return the actual
278 * physical page frame number.
279 */
280 static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
281 {
282 unsigned long coded_mem_map =
283 (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
284 BUILD_BUG_ON(SECTION_MAP_LAST_BIT > (1UL<<PFN_SECTION_SHIFT));
285 BUG_ON(coded_mem_map & ~SECTION_MAP_MASK);
286 return coded_mem_map;
287 }
288
289 #ifdef CONFIG_MEMORY_HOTPLUG
290 /*
291 * Decode mem_map from the coded memmap
292 */
293 struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
294 {
295 /* mask off the extra low bits of information */
296 coded_mem_map &= SECTION_MAP_MASK;
297 return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
298 }
299 #endif /* CONFIG_MEMORY_HOTPLUG */
300
301 static void __meminit sparse_init_one_section(struct mem_section *ms,
302 unsigned long pnum, struct page *mem_map,
303 struct mem_section_usage *usage, unsigned long flags)
304 {
305 ms->section_mem_map &= ~SECTION_MAP_MASK;
306 ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum)
307 | SECTION_HAS_MEM_MAP | flags;
308 ms->usage = usage;
309 }
310
311 static unsigned long usemap_size(void)
312 {
313 return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
314 }
315
316 size_t mem_section_usage_size(void)
317 {
318 return sizeof(struct mem_section_usage) + usemap_size();
319 }
320
321 static inline phys_addr_t pgdat_to_phys(struct pglist_data *pgdat)
322 {
323 #ifndef CONFIG_NUMA
324 VM_BUG_ON(pgdat != &contig_page_data);
325 return __pa_symbol(&contig_page_data);
326 #else
327 return __pa(pgdat);
328 #endif
329 }
330
331 #ifdef CONFIG_MEMORY_HOTREMOVE
332 static struct mem_section_usage * __init
333 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
334 unsigned long size)
335 {
336 struct mem_section_usage *usage;
337 unsigned long goal, limit;
338 int nid;
339 /*
340 * A page may contain usemaps for other sections preventing the
341 * page being freed and making a section unremovable while
342 * other sections referencing the usemap remain active. Similarly,
343 * a pgdat can prevent a section being removed. If section A
344 * contains a pgdat and section B contains the usemap, both
345 * sections become inter-dependent. This allocates usemaps
346 * from the same section as the pgdat where possible to avoid
347 * this problem.
348 */
349 goal = pgdat_to_phys(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
350 limit = goal + (1UL << PA_SECTION_SHIFT);
351 nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
352 again:
353 usage = memblock_alloc_try_nid(size, SMP_CACHE_BYTES, goal, limit, nid);
354 if (!usage && limit) {
355 limit = 0;
356 goto again;
357 }
358 return usage;
359 }
360
361 static void __init check_usemap_section_nr(int nid,
362 struct mem_section_usage *usage)
363 {
364 unsigned long usemap_snr, pgdat_snr;
365 static unsigned long old_usemap_snr;
366 static unsigned long old_pgdat_snr;
367 struct pglist_data *pgdat = NODE_DATA(nid);
368 int usemap_nid;
369
370 /* First call */
371 if (!old_usemap_snr) {
372 old_usemap_snr = NR_MEM_SECTIONS;
373 old_pgdat_snr = NR_MEM_SECTIONS;
374 }
375
376 usemap_snr = pfn_to_section_nr(__pa(usage) >> PAGE_SHIFT);
377 pgdat_snr = pfn_to_section_nr(pgdat_to_phys(pgdat) >> PAGE_SHIFT);
378 if (usemap_snr == pgdat_snr)
379 return;
380
381 if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
382 /* skip redundant message */
383 return;
384
385 old_usemap_snr = usemap_snr;
386 old_pgdat_snr = pgdat_snr;
387
388 usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
389 if (usemap_nid != nid) {
390 pr_info("node %d must be removed before remove section %ld\n",
391 nid, usemap_snr);
392 return;
393 }
394 /*
395 * There is a circular dependency.
396 * Some platforms allow un-removable section because they will just
397 * gather other removable sections for dynamic partitioning.
398 * Just notify un-removable section's number here.
399 */
400 pr_info("Section %ld and %ld (node %d) have a circular dependency on usemap and pgdat allocations\n",
401 usemap_snr, pgdat_snr, nid);
402 }
403 #else
404 static struct mem_section_usage * __init
405 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
406 unsigned long size)
407 {
408 return memblock_alloc_node(size, SMP_CACHE_BYTES, pgdat->node_id);
409 }
410
411 static void __init check_usemap_section_nr(int nid,
412 struct mem_section_usage *usage)
413 {
414 }
415 #endif /* CONFIG_MEMORY_HOTREMOVE */
416
417 #ifdef CONFIG_SPARSEMEM_VMEMMAP
418 static unsigned long __init section_map_size(void)
419 {
420 return ALIGN(sizeof(struct page) * PAGES_PER_SECTION, PMD_SIZE);
421 }
422
423 #else
424 static unsigned long __init section_map_size(void)
425 {
426 return PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
427 }
428
429 struct page __init *__populate_section_memmap(unsigned long pfn,
430 unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
431 {
432 unsigned long size = section_map_size();
433 struct page *map = sparse_buffer_alloc(size);
434 phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
435
436 if (map)
437 return map;
438
439 map = memmap_alloc(size, size, addr, nid, false);
440 if (!map)
441 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%pa\n",
442 __func__, size, PAGE_SIZE, nid, &addr);
443
444 return map;
445 }
446 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
447
448 static void *sparsemap_buf __meminitdata;
449 static void *sparsemap_buf_end __meminitdata;
450
451 static inline void __meminit sparse_buffer_free(unsigned long size)
452 {
453 WARN_ON(!sparsemap_buf || size == 0);
454 memblock_free_early(__pa(sparsemap_buf), size);
455 }
456
457 static void __init sparse_buffer_init(unsigned long size, int nid)
458 {
459 phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
460 WARN_ON(sparsemap_buf); /* forgot to call sparse_buffer_fini()? */
461 /*
462 * Pre-allocated buffer is mainly used by __populate_section_memmap
463 * and we want it to be properly aligned to the section size - this is
464 * especially the case for VMEMMAP which maps memmap to PMDs
465 */
466 sparsemap_buf = memmap_alloc(size, section_map_size(), addr, nid, true);
467 sparsemap_buf_end = sparsemap_buf + size;
468 }
469
470 static void __init sparse_buffer_fini(void)
471 {
472 unsigned long size = sparsemap_buf_end - sparsemap_buf;
473
474 if (sparsemap_buf && size > 0)
475 sparse_buffer_free(size);
476 sparsemap_buf = NULL;
477 }
478
479 void * __meminit sparse_buffer_alloc(unsigned long size)
480 {
481 void *ptr = NULL;
482
483 if (sparsemap_buf) {
484 ptr = (void *) roundup((unsigned long)sparsemap_buf, size);
485 if (ptr + size > sparsemap_buf_end)
486 ptr = NULL;
487 else {
488 /* Free redundant aligned space */
489 if ((unsigned long)(ptr - sparsemap_buf) > 0)
490 sparse_buffer_free((unsigned long)(ptr - sparsemap_buf));
491 sparsemap_buf = ptr + size;
492 }
493 }
494 return ptr;
495 }
496
497 void __weak __meminit vmemmap_populate_print_last(void)
498 {
499 }
500
501 /*
502 * Initialize sparse on a specific node. The node spans [pnum_begin, pnum_end)
503 * And number of present sections in this node is map_count.
504 */
505 static void __init sparse_init_nid(int nid, unsigned long pnum_begin,
506 unsigned long pnum_end,
507 unsigned long map_count)
508 {
509 struct mem_section_usage *usage;
510 unsigned long pnum;
511 struct page *map;
512
513 usage = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nid),
514 mem_section_usage_size() * map_count);
515 if (!usage) {
516 pr_err("%s: node[%d] usemap allocation failed", __func__, nid);
517 goto failed;
518 }
519 sparse_buffer_init(map_count * section_map_size(), nid);
520 for_each_present_section_nr(pnum_begin, pnum) {
521 unsigned long pfn = section_nr_to_pfn(pnum);
522
523 if (pnum >= pnum_end)
524 break;
525
526 map = __populate_section_memmap(pfn, PAGES_PER_SECTION,
527 nid, NULL);
528 if (!map) {
529 pr_err("%s: node[%d] memory map backing failed. Some memory will not be available.",
530 __func__, nid);
531 pnum_begin = pnum;
532 sparse_buffer_fini();
533 goto failed;
534 }
535 check_usemap_section_nr(nid, usage);
536 sparse_init_one_section(__nr_to_section(pnum), pnum, map, usage,
537 SECTION_IS_EARLY);
538 usage = (void *) usage + mem_section_usage_size();
539 }
540 sparse_buffer_fini();
541 return;
542 failed:
543 /* We failed to allocate, mark all the following pnums as not present */
544 for_each_present_section_nr(pnum_begin, pnum) {
545 struct mem_section *ms;
546
547 if (pnum >= pnum_end)
548 break;
549 ms = __nr_to_section(pnum);
550 ms->section_mem_map = 0;
551 }
552 }
553
554 /*
555 * Allocate the accumulated non-linear sections, allocate a mem_map
556 * for each and record the physical to section mapping.
557 */
558 void __init sparse_init(void)
559 {
560 unsigned long pnum_end, pnum_begin, map_count = 1;
561 int nid_begin;
562
563 memblocks_present();
564
565 pnum_begin = first_present_section_nr();
566 nid_begin = sparse_early_nid(__nr_to_section(pnum_begin));
567
568 /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
569 set_pageblock_order();
570
571 for_each_present_section_nr(pnum_begin + 1, pnum_end) {
572 int nid = sparse_early_nid(__nr_to_section(pnum_end));
573
574 if (nid == nid_begin) {
575 map_count++;
576 continue;
577 }
578 /* Init node with sections in range [pnum_begin, pnum_end) */
579 sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
580 nid_begin = nid;
581 pnum_begin = pnum_end;
582 map_count = 1;
583 }
584 /* cover the last node */
585 sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
586 vmemmap_populate_print_last();
587 }
588
589 #ifdef CONFIG_MEMORY_HOTPLUG
590
591 /* Mark all memory sections within the pfn range as online */
592 void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
593 {
594 unsigned long pfn;
595
596 for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
597 unsigned long section_nr = pfn_to_section_nr(pfn);
598 struct mem_section *ms;
599
600 /* onlining code should never touch invalid ranges */
601 if (WARN_ON(!valid_section_nr(section_nr)))
602 continue;
603
604 ms = __nr_to_section(section_nr);
605 ms->section_mem_map |= SECTION_IS_ONLINE;
606 }
607 }
608
609 /* Mark all memory sections within the pfn range as offline */
610 void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
611 {
612 unsigned long pfn;
613
614 for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
615 unsigned long section_nr = pfn_to_section_nr(pfn);
616 struct mem_section *ms;
617
618 /*
619 * TODO this needs some double checking. Offlining code makes
620 * sure to check pfn_valid but those checks might be just bogus
621 */
622 if (WARN_ON(!valid_section_nr(section_nr)))
623 continue;
624
625 ms = __nr_to_section(section_nr);
626 ms->section_mem_map &= ~SECTION_IS_ONLINE;
627 }
628 }
629
630 #ifdef CONFIG_SPARSEMEM_VMEMMAP
631 static struct page * __meminit populate_section_memmap(unsigned long pfn,
632 unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
633 {
634 return __populate_section_memmap(pfn, nr_pages, nid, altmap);
635 }
636
637 static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
638 struct vmem_altmap *altmap)
639 {
640 unsigned long start = (unsigned long) pfn_to_page(pfn);
641 unsigned long end = start + nr_pages * sizeof(struct page);
642
643 vmemmap_free(start, end, altmap);
644 }
645 static void free_map_bootmem(struct page *memmap)
646 {
647 unsigned long start = (unsigned long)memmap;
648 unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
649
650 vmemmap_free(start, end, NULL);
651 }
652
653 static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
654 {
655 DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
656 DECLARE_BITMAP(tmp, SUBSECTIONS_PER_SECTION) = { 0 };
657 struct mem_section *ms = __pfn_to_section(pfn);
658 unsigned long *subsection_map = ms->usage
659 ? &ms->usage->subsection_map[0] : NULL;
660
661 subsection_mask_set(map, pfn, nr_pages);
662 if (subsection_map)
663 bitmap_and(tmp, map, subsection_map, SUBSECTIONS_PER_SECTION);
664
665 if (WARN(!subsection_map || !bitmap_equal(tmp, map, SUBSECTIONS_PER_SECTION),
666 "section already deactivated (%#lx + %ld)\n",
667 pfn, nr_pages))
668 return -EINVAL;
669
670 bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION);
671 return 0;
672 }
673
674 static bool is_subsection_map_empty(struct mem_section *ms)
675 {
676 return bitmap_empty(&ms->usage->subsection_map[0],
677 SUBSECTIONS_PER_SECTION);
678 }
679
680 static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
681 {
682 struct mem_section *ms = __pfn_to_section(pfn);
683 DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
684 unsigned long *subsection_map;
685 int rc = 0;
686
687 subsection_mask_set(map, pfn, nr_pages);
688
689 subsection_map = &ms->usage->subsection_map[0];
690
691 if (bitmap_empty(map, SUBSECTIONS_PER_SECTION))
692 rc = -EINVAL;
693 else if (bitmap_intersects(map, subsection_map, SUBSECTIONS_PER_SECTION))
694 rc = -EEXIST;
695 else
696 bitmap_or(subsection_map, map, subsection_map,
697 SUBSECTIONS_PER_SECTION);
698
699 return rc;
700 }
701 #else
702 struct page * __meminit populate_section_memmap(unsigned long pfn,
703 unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
704 {
705 return kvmalloc_node(array_size(sizeof(struct page),
706 PAGES_PER_SECTION), GFP_KERNEL, nid);
707 }
708
709 static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
710 struct vmem_altmap *altmap)
711 {
712 kvfree(pfn_to_page(pfn));
713 }
714
715 static void free_map_bootmem(struct page *memmap)
716 {
717 unsigned long maps_section_nr, removing_section_nr, i;
718 unsigned long magic, nr_pages;
719 struct page *page = virt_to_page(memmap);
720
721 nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
722 >> PAGE_SHIFT;
723
724 for (i = 0; i < nr_pages; i++, page++) {
725 magic = (unsigned long) page->freelist;
726
727 BUG_ON(magic == NODE_INFO);
728
729 maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
730 removing_section_nr = page_private(page);
731
732 /*
733 * When this function is called, the removing section is
734 * logical offlined state. This means all pages are isolated
735 * from page allocator. If removing section's memmap is placed
736 * on the same section, it must not be freed.
737 * If it is freed, page allocator may allocate it which will
738 * be removed physically soon.
739 */
740 if (maps_section_nr != removing_section_nr)
741 put_page_bootmem(page);
742 }
743 }
744
745 static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
746 {
747 return 0;
748 }
749
750 static bool is_subsection_map_empty(struct mem_section *ms)
751 {
752 return true;
753 }
754
755 static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
756 {
757 return 0;
758 }
759 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
760
761 /*
762 * To deactivate a memory region, there are 3 cases to handle across
763 * two configurations (SPARSEMEM_VMEMMAP={y,n}):
764 *
765 * 1. deactivation of a partial hot-added section (only possible in
766 * the SPARSEMEM_VMEMMAP=y case).
767 * a) section was present at memory init.
768 * b) section was hot-added post memory init.
769 * 2. deactivation of a complete hot-added section.
770 * 3. deactivation of a complete section from memory init.
771 *
772 * For 1, when subsection_map does not empty we will not be freeing the
773 * usage map, but still need to free the vmemmap range.
774 *
775 * For 2 and 3, the SPARSEMEM_VMEMMAP={y,n} cases are unified
776 */
777 static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
778 struct vmem_altmap *altmap)
779 {
780 struct mem_section *ms = __pfn_to_section(pfn);
781 bool section_is_early = early_section(ms);
782 struct page *memmap = NULL;
783 bool empty;
784
785 if (clear_subsection_map(pfn, nr_pages))
786 return;
787
788 empty = is_subsection_map_empty(ms);
789 if (empty) {
790 unsigned long section_nr = pfn_to_section_nr(pfn);
791
792 /*
793 * When removing an early section, the usage map is kept (as the
794 * usage maps of other sections fall into the same page). It
795 * will be re-used when re-adding the section - which is then no
796 * longer an early section. If the usage map is PageReserved, it
797 * was allocated during boot.
798 */
799 if (!PageReserved(virt_to_page(ms->usage))) {
800 kfree(ms->usage);
801 ms->usage = NULL;
802 }
803 memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
804 /*
805 * Mark the section invalid so that valid_section()
806 * return false. This prevents code from dereferencing
807 * ms->usage array.
808 */
809 ms->section_mem_map &= ~SECTION_HAS_MEM_MAP;
810 }
811
812 /*
813 * The memmap of early sections is always fully populated. See
814 * section_activate() and pfn_valid() .
815 */
816 if (!section_is_early)
817 depopulate_section_memmap(pfn, nr_pages, altmap);
818 else if (memmap)
819 free_map_bootmem(memmap);
820
821 if (empty)
822 ms->section_mem_map = (unsigned long)NULL;
823 }
824
825 static struct page * __meminit section_activate(int nid, unsigned long pfn,
826 unsigned long nr_pages, struct vmem_altmap *altmap)
827 {
828 struct mem_section *ms = __pfn_to_section(pfn);
829 struct mem_section_usage *usage = NULL;
830 struct page *memmap;
831 int rc = 0;
832
833 if (!ms->usage) {
834 usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
835 if (!usage)
836 return ERR_PTR(-ENOMEM);
837 ms->usage = usage;
838 }
839
840 rc = fill_subsection_map(pfn, nr_pages);
841 if (rc) {
842 if (usage)
843 ms->usage = NULL;
844 kfree(usage);
845 return ERR_PTR(rc);
846 }
847
848 /*
849 * The early init code does not consider partially populated
850 * initial sections, it simply assumes that memory will never be
851 * referenced. If we hot-add memory into such a section then we
852 * do not need to populate the memmap and can simply reuse what
853 * is already there.
854 */
855 if (nr_pages < PAGES_PER_SECTION && early_section(ms))
856 return pfn_to_page(pfn);
857
858 memmap = populate_section_memmap(pfn, nr_pages, nid, altmap);
859 if (!memmap) {
860 section_deactivate(pfn, nr_pages, altmap);
861 return ERR_PTR(-ENOMEM);
862 }
863
864 return memmap;
865 }
866
867 /**
868 * sparse_add_section - add a memory section, or populate an existing one
869 * @nid: The node to add section on
870 * @start_pfn: start pfn of the memory range
871 * @nr_pages: number of pfns to add in the section
872 * @altmap: device page map
873 *
874 * This is only intended for hotplug.
875 *
876 * Note that only VMEMMAP supports sub-section aligned hotplug,
877 * the proper alignment and size are gated by check_pfn_span().
878 *
879 *
880 * Return:
881 * * 0 - On success.
882 * * -EEXIST - Section has been present.
883 * * -ENOMEM - Out of memory.
884 */
885 int __meminit sparse_add_section(int nid, unsigned long start_pfn,
886 unsigned long nr_pages, struct vmem_altmap *altmap)
887 {
888 unsigned long section_nr = pfn_to_section_nr(start_pfn);
889 struct mem_section *ms;
890 struct page *memmap;
891 int ret;
892
893 ret = sparse_index_init(section_nr, nid);
894 if (ret < 0)
895 return ret;
896
897 memmap = section_activate(nid, start_pfn, nr_pages, altmap);
898 if (IS_ERR(memmap))
899 return PTR_ERR(memmap);
900
901 /*
902 * Poison uninitialized struct pages in order to catch invalid flags
903 * combinations.
904 */
905 page_init_poison(memmap, sizeof(struct page) * nr_pages);
906
907 ms = __nr_to_section(section_nr);
908 set_section_nid(section_nr, nid);
909 __section_mark_present(ms, section_nr);
910
911 /* Align memmap to section boundary in the subsection case */
912 if (section_nr_to_pfn(section_nr) != start_pfn)
913 memmap = pfn_to_page(section_nr_to_pfn(section_nr));
914 sparse_init_one_section(ms, section_nr, memmap, ms->usage, 0);
915
916 return 0;
917 }
918
919 #ifdef CONFIG_MEMORY_FAILURE
920 static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
921 {
922 int i;
923
924 /*
925 * A further optimization is to have per section refcounted
926 * num_poisoned_pages. But that would need more space per memmap, so
927 * for now just do a quick global check to speed up this routine in the
928 * absence of bad pages.
929 */
930 if (atomic_long_read(&num_poisoned_pages) == 0)
931 return;
932
933 for (i = 0; i < nr_pages; i++) {
934 if (PageHWPoison(&memmap[i])) {
935 num_poisoned_pages_dec();
936 ClearPageHWPoison(&memmap[i]);
937 }
938 }
939 }
940 #else
941 static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
942 {
943 }
944 #endif
945
946 void sparse_remove_section(struct mem_section *ms, unsigned long pfn,
947 unsigned long nr_pages, unsigned long map_offset,
948 struct vmem_altmap *altmap)
949 {
950 clear_hwpoisoned_pages(pfn_to_page(pfn) + map_offset,
951 nr_pages - map_offset);
952 section_deactivate(pfn, nr_pages, altmap);
953 }
954 #endif /* CONFIG_MEMORY_HOTPLUG */