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
27struct mem_section **mem_section;
28#else
29struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
30 ____cacheline_internodealigned_in_smp;
31#endif
32EXPORT_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
41static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
42#else
43static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
44#endif
45
46int page_to_nid(const struct page *page)
47{
48 return section_to_node_table[page_to_section(page)];
49}
50EXPORT_SYMBOL(page_to_nid);
51
52static 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 */
57static inline void set_section_nid(unsigned long section_nr, int nid)
58{
59}
60#endif
61
62#ifdef CONFIG_SPARSEMEM_EXTREME
63static 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(size: array_size, GFP_KERNEL, node: nid);
71 } else {
72 section = memblock_alloc_node(size: array_size, SMP_CACHE_BYTES,
73 nid);
74 if (!section)
75 panic(fmt: "%s: Failed to allocate %lu bytes nid=%d\n",
76 __func__, array_size, nid);
77 }
78
79 return section;
80}
81
82static 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 */
106static 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 */
118static inline unsigned long sparse_encode_early_nid(int nid)
119{
120 return ((unsigned long)nid << SECTION_NID_SHIFT);
121}
122
123static 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 */
129static 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 */
163unsigned long __highest_present_section_nr;
164static 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 = next_present_section_nr(section_nr))
177
178static inline unsigned long first_present_section_nr(void)
179{
180 return next_present_section_nr(section_nr: -1);
181}
182
183#ifdef CONFIG_SPARSEMEM_VMEMMAP
184static void subsection_mask_set(unsigned long *map, unsigned long pfn,
185 unsigned long nr_pages)
186{
187 int idx = subsection_map_index(pfn);
188 int end = subsection_map_index(pfn: pfn + nr_pages - 1);
189
190 bitmap_set(map, start: idx, nbits: end - idx + 1);
191}
192
193void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
194{
195 int end_sec = pfn_to_section_nr(pfn: pfn + nr_pages - 1);
196 unsigned long nr, start_sec = pfn_to_section_nr(pfn);
197
198 if (!nr_pages)
199 return;
200
201 for (nr = start_sec; nr <= end_sec; nr++) {
202 struct mem_section *ms;
203 unsigned long pfns;
204
205 pfns = min(nr_pages, PAGES_PER_SECTION
206 - (pfn & ~PAGE_SECTION_MASK));
207 ms = __nr_to_section(nr);
208 subsection_mask_set(map: ms->usage->subsection_map, pfn, nr_pages: pfns);
209
210 pr_debug("%s: sec: %lu pfns: %lu set(%d, %d)\n", __func__, nr,
211 pfns, subsection_map_index(pfn),
212 subsection_map_index(pfn + pfns - 1));
213
214 pfn += pfns;
215 nr_pages -= pfns;
216 }
217}
218#else
219void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
220{
221}
222#endif
223
224/* Record a memory area against a node. */
225static void __init memory_present(int nid, unsigned long start, unsigned long end)
226{
227 unsigned long pfn;
228
229#ifdef CONFIG_SPARSEMEM_EXTREME
230 if (unlikely(!mem_section)) {
231 unsigned long size, align;
232
233 size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
234 align = 1 << (INTERNODE_CACHE_SHIFT);
235 mem_section = memblock_alloc(size, align);
236 if (!mem_section)
237 panic(fmt: "%s: Failed to allocate %lu bytes align=0x%lx\n",
238 __func__, size, align);
239 }
240#endif
241
242 start &= PAGE_SECTION_MASK;
243 mminit_validate_memmodel_limits(start_pfn: &start, end_pfn: &end);
244 for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
245 unsigned long section = pfn_to_section_nr(pfn);
246 struct mem_section *ms;
247
248 sparse_index_init(section_nr: section, nid);
249 set_section_nid(section_nr: section, nid);
250
251 ms = __nr_to_section(nr: section);
252 if (!ms->section_mem_map) {
253 ms->section_mem_map = sparse_encode_early_nid(nid) |
254 SECTION_IS_ONLINE;
255 __section_mark_present(ms, section_nr: section);
256 }
257 }
258}
259
260/*
261 * Mark all memblocks as present using memory_present().
262 * This is a convenience function that is useful to mark all of the systems
263 * memory as present during initialization.
264 */
265static void __init memblocks_present(void)
266{
267 unsigned long start, end;
268 int i, nid;
269
270 for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid)
271 memory_present(nid, start, end);
272}
273
274/*
275 * Subtle, we encode the real pfn into the mem_map such that
276 * the identity pfn - section_mem_map will return the actual
277 * physical page frame number.
278 */
279static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
280{
281 unsigned long coded_mem_map =
282 (unsigned long)(mem_map - (section_nr_to_pfn(sec: pnum)));
283 BUILD_BUG_ON(SECTION_MAP_LAST_BIT > PFN_SECTION_SHIFT);
284 BUG_ON(coded_mem_map & ~SECTION_MAP_MASK);
285 return coded_mem_map;
286}
287
288#ifdef CONFIG_MEMORY_HOTPLUG
289/*
290 * Decode mem_map from the coded memmap
291 */
292struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
293{
294 /* mask off the extra low bits of information */
295 coded_mem_map &= SECTION_MAP_MASK;
296 return ((struct page *)coded_mem_map) + section_nr_to_pfn(sec: pnum);
297}
298#endif /* CONFIG_MEMORY_HOTPLUG */
299
300static void __meminit sparse_init_one_section(struct mem_section *ms,
301 unsigned long pnum, struct page *mem_map,
302 struct mem_section_usage *usage, unsigned long flags)
303{
304 ms->section_mem_map &= ~SECTION_MAP_MASK;
305 ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum)
306 | SECTION_HAS_MEM_MAP | flags;
307 ms->usage = usage;
308}
309
310static unsigned long usemap_size(void)
311{
312 return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
313}
314
315size_t mem_section_usage_size(void)
316{
317 return sizeof(struct mem_section_usage) + usemap_size();
318}
319
320#ifdef CONFIG_MEMORY_HOTREMOVE
321static 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
331static struct mem_section_usage * __init
332sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
333 unsigned long size)
334{
335 struct mem_section_usage *usage;
336 unsigned long goal, limit;
337 int nid;
338 /*
339 * A page may contain usemaps for other sections preventing the
340 * page being freed and making a section unremovable while
341 * other sections referencing the usemap remain active. Similarly,
342 * a pgdat can prevent a section being removed. If section A
343 * contains a pgdat and section B contains the usemap, both
344 * sections become inter-dependent. This allocates usemaps
345 * from the same section as the pgdat where possible to avoid
346 * this problem.
347 */
348 goal = pgdat_to_phys(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
349 limit = goal + (1UL << PA_SECTION_SHIFT);
350 nid = early_pfn_to_nid(pfn: goal >> PAGE_SHIFT);
351again:
352 usage = memblock_alloc_try_nid(size, SMP_CACHE_BYTES, min_addr: goal, max_addr: limit, nid);
353 if (!usage && limit) {
354 limit = 0;
355 goto again;
356 }
357 return usage;
358}
359
360static void __init check_usemap_section_nr(int nid,
361 struct mem_section_usage *usage)
362{
363 unsigned long usemap_snr, pgdat_snr;
364 static unsigned long old_usemap_snr;
365 static unsigned long old_pgdat_snr;
366 struct pglist_data *pgdat = NODE_DATA(nid);
367 int usemap_nid;
368
369 /* First call */
370 if (!old_usemap_snr) {
371 old_usemap_snr = NR_MEM_SECTIONS;
372 old_pgdat_snr = NR_MEM_SECTIONS;
373 }
374
375 usemap_snr = pfn_to_section_nr(__pa(usage) >> PAGE_SHIFT);
376 pgdat_snr = pfn_to_section_nr(pfn: pgdat_to_phys(pgdat) >> PAGE_SHIFT);
377 if (usemap_snr == pgdat_snr)
378 return;
379
380 if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
381 /* skip redundant message */
382 return;
383
384 old_usemap_snr = usemap_snr;
385 old_pgdat_snr = pgdat_snr;
386
387 usemap_nid = sparse_early_nid(section: __nr_to_section(nr: usemap_snr));
388 if (usemap_nid != nid) {
389 pr_info("node %d must be removed before remove section %ld\n",
390 nid, usemap_snr);
391 return;
392 }
393 /*
394 * There is a circular dependency.
395 * Some platforms allow un-removable section because they will just
396 * gather other removable sections for dynamic partitioning.
397 * Just notify un-removable section's number here.
398 */
399 pr_info("Section %ld and %ld (node %d) have a circular dependency on usemap and pgdat allocations\n",
400 usemap_snr, pgdat_snr, nid);
401}
402#else
403static struct mem_section_usage * __init
404sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
405 unsigned long size)
406{
407 return memblock_alloc_node(size, SMP_CACHE_BYTES, pgdat->node_id);
408}
409
410static void __init check_usemap_section_nr(int nid,
411 struct mem_section_usage *usage)
412{
413}
414#endif /* CONFIG_MEMORY_HOTREMOVE */
415
416#ifdef CONFIG_SPARSEMEM_VMEMMAP
417static unsigned long __init section_map_size(void)
418{
419 return ALIGN(sizeof(struct page) * PAGES_PER_SECTION, PMD_SIZE);
420}
421
422#else
423static unsigned long __init section_map_size(void)
424{
425 return PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
426}
427
428struct page __init *__populate_section_memmap(unsigned long pfn,
429 unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
430 struct dev_pagemap *pgmap)
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
448static void *sparsemap_buf __meminitdata;
449static void *sparsemap_buf_end __meminitdata;
450
451static inline void __meminit sparse_buffer_free(unsigned long size)
452{
453 WARN_ON(!sparsemap_buf || size == 0);
454 memblock_free(ptr: sparsemap_buf, size);
455}
456
457static 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, align: section_map_size(), min_addr: addr, nid, exact_nid: true);
467 sparsemap_buf_end = sparsemap_buf + size;
468}
469
470static 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
479void * __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(size: (unsigned long)(ptr - sparsemap_buf));
491 sparsemap_buf = ptr + size;
492 }
493 }
494 return ptr;
495}
496
497void __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 */
505static 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 size: 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(size: map_count * section_map_size(), nid);
520 for_each_present_section_nr(pnum_begin, pnum) {
521 unsigned long pfn = section_nr_to_pfn(sec: pnum);
522
523 if (pnum >= pnum_end)
524 break;
525
526 map = __populate_section_memmap(pfn, PAGES_PER_SECTION,
527 nid, NULL, 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(ms: __nr_to_section(nr: pnum), pnum, mem_map: map, usage,
537 SECTION_IS_EARLY);
538 usage = (void *) usage + mem_section_usage_size();
539 }
540 sparse_buffer_fini();
541 return;
542failed:
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(nr: 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 */
558void __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(section: __nr_to_section(nr: 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(section: __nr_to_section(nr: 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: 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: 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 */
592void 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(nr: section_nr);
605 ms->section_mem_map |= SECTION_IS_ONLINE;
606 }
607}
608
609/* Mark all memory sections within the pfn range as offline */
610void 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(nr: section_nr);
626 ms->section_mem_map &= ~SECTION_IS_ONLINE;
627 }
628}
629
630#ifdef CONFIG_SPARSEMEM_VMEMMAP
631static struct page * __meminit populate_section_memmap(unsigned long pfn,
632 unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
633 struct dev_pagemap *pgmap)
634{
635 return __populate_section_memmap(pfn, nr_pages, nid, altmap, pgmap);
636}
637
638static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
639 struct vmem_altmap *altmap)
640{
641 unsigned long start = (unsigned long) pfn_to_page(pfn);
642 unsigned long end = start + nr_pages * sizeof(struct page);
643
644 vmemmap_free(start, end, altmap);
645}
646static void free_map_bootmem(struct page *memmap)
647{
648 unsigned long start = (unsigned long)memmap;
649 unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
650
651 vmemmap_free(start, end, NULL);
652}
653
654static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
655{
656 DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
657 DECLARE_BITMAP(tmp, SUBSECTIONS_PER_SECTION) = { 0 };
658 struct mem_section *ms = __pfn_to_section(pfn);
659 unsigned long *subsection_map = ms->usage
660 ? &ms->usage->subsection_map[0] : NULL;
661
662 subsection_mask_set(map, pfn, nr_pages);
663 if (subsection_map)
664 bitmap_and(dst: tmp, src1: map, src2: subsection_map, SUBSECTIONS_PER_SECTION);
665
666 if (WARN(!subsection_map || !bitmap_equal(tmp, map, SUBSECTIONS_PER_SECTION),
667 "section already deactivated (%#lx + %ld)\n",
668 pfn, nr_pages))
669 return -EINVAL;
670
671 bitmap_xor(dst: subsection_map, src1: map, src2: subsection_map, SUBSECTIONS_PER_SECTION);
672 return 0;
673}
674
675static bool is_subsection_map_empty(struct mem_section *ms)
676{
677 return bitmap_empty(src: &ms->usage->subsection_map[0],
678 SUBSECTIONS_PER_SECTION);
679}
680
681static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
682{
683 struct mem_section *ms = __pfn_to_section(pfn);
684 DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
685 unsigned long *subsection_map;
686 int rc = 0;
687
688 subsection_mask_set(map, pfn, nr_pages);
689
690 subsection_map = &ms->usage->subsection_map[0];
691
692 if (bitmap_empty(src: map, SUBSECTIONS_PER_SECTION))
693 rc = -EINVAL;
694 else if (bitmap_intersects(src1: map, src2: subsection_map, SUBSECTIONS_PER_SECTION))
695 rc = -EEXIST;
696 else
697 bitmap_or(dst: subsection_map, src1: map, src2: subsection_map,
698 SUBSECTIONS_PER_SECTION);
699
700 return rc;
701}
702#else
703static struct page * __meminit populate_section_memmap(unsigned long pfn,
704 unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
705 struct dev_pagemap *pgmap)
706{
707 return kvmalloc_node(array_size(sizeof(struct page),
708 PAGES_PER_SECTION), GFP_KERNEL, nid);
709}
710
711static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
712 struct vmem_altmap *altmap)
713{
714 kvfree(pfn_to_page(pfn));
715}
716
717static void free_map_bootmem(struct page *memmap)
718{
719 unsigned long maps_section_nr, removing_section_nr, i;
720 unsigned long magic, nr_pages;
721 struct page *page = virt_to_page(memmap);
722
723 nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
724 >> PAGE_SHIFT;
725
726 for (i = 0; i < nr_pages; i++, page++) {
727 magic = page->index;
728
729 BUG_ON(magic == NODE_INFO);
730
731 maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
732 removing_section_nr = page_private(page);
733
734 /*
735 * When this function is called, the removing section is
736 * logical offlined state. This means all pages are isolated
737 * from page allocator. If removing section's memmap is placed
738 * on the same section, it must not be freed.
739 * If it is freed, page allocator may allocate it which will
740 * be removed physically soon.
741 */
742 if (maps_section_nr != removing_section_nr)
743 put_page_bootmem(page);
744 }
745}
746
747static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
748{
749 return 0;
750}
751
752static bool is_subsection_map_empty(struct mem_section *ms)
753{
754 return true;
755}
756
757static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
758{
759 return 0;
760}
761#endif /* CONFIG_SPARSEMEM_VMEMMAP */
762
763/*
764 * To deactivate a memory region, there are 3 cases to handle across
765 * two configurations (SPARSEMEM_VMEMMAP={y,n}):
766 *
767 * 1. deactivation of a partial hot-added section (only possible in
768 * the SPARSEMEM_VMEMMAP=y case).
769 * a) section was present at memory init.
770 * b) section was hot-added post memory init.
771 * 2. deactivation of a complete hot-added section.
772 * 3. deactivation of a complete section from memory init.
773 *
774 * For 1, when subsection_map does not empty we will not be freeing the
775 * usage map, but still need to free the vmemmap range.
776 *
777 * For 2 and 3, the SPARSEMEM_VMEMMAP={y,n} cases are unified
778 */
779static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
780 struct vmem_altmap *altmap)
781{
782 struct mem_section *ms = __pfn_to_section(pfn);
783 bool section_is_early = early_section(section: ms);
784 struct page *memmap = NULL;
785 bool empty;
786
787 if (clear_subsection_map(pfn, nr_pages))
788 return;
789
790 empty = is_subsection_map_empty(ms);
791 if (empty) {
792 unsigned long section_nr = pfn_to_section_nr(pfn);
793
794 /*
795 * When removing an early section, the usage map is kept (as the
796 * usage maps of other sections fall into the same page). It
797 * will be re-used when re-adding the section - which is then no
798 * longer an early section. If the usage map is PageReserved, it
799 * was allocated during boot.
800 */
801 if (!PageReserved(virt_to_page(ms->usage))) {
802 kfree(objp: ms->usage);
803 ms->usage = NULL;
804 }
805 memmap = sparse_decode_mem_map(coded_mem_map: ms->section_mem_map, pnum: section_nr);
806 /*
807 * Mark the section invalid so that valid_section()
808 * return false. This prevents code from dereferencing
809 * ms->usage array.
810 */
811 ms->section_mem_map &= ~SECTION_HAS_MEM_MAP;
812 }
813
814 /*
815 * The memmap of early sections is always fully populated. See
816 * section_activate() and pfn_valid() .
817 */
818 if (!section_is_early)
819 depopulate_section_memmap(pfn, nr_pages, altmap);
820 else if (memmap)
821 free_map_bootmem(memmap);
822
823 if (empty)
824 ms->section_mem_map = (unsigned long)NULL;
825}
826
827static struct page * __meminit section_activate(int nid, unsigned long pfn,
828 unsigned long nr_pages, struct vmem_altmap *altmap,
829 struct dev_pagemap *pgmap)
830{
831 struct mem_section *ms = __pfn_to_section(pfn);
832 struct mem_section_usage *usage = NULL;
833 struct page *memmap;
834 int rc;
835
836 if (!ms->usage) {
837 usage = kzalloc(size: mem_section_usage_size(), GFP_KERNEL);
838 if (!usage)
839 return ERR_PTR(error: -ENOMEM);
840 ms->usage = usage;
841 }
842
843 rc = fill_subsection_map(pfn, nr_pages);
844 if (rc) {
845 if (usage)
846 ms->usage = NULL;
847 kfree(objp: usage);
848 return ERR_PTR(error: rc);
849 }
850
851 /*
852 * The early init code does not consider partially populated
853 * initial sections, it simply assumes that memory will never be
854 * referenced. If we hot-add memory into such a section then we
855 * do not need to populate the memmap and can simply reuse what
856 * is already there.
857 */
858 if (nr_pages < PAGES_PER_SECTION && early_section(section: ms))
859 return pfn_to_page(pfn);
860
861 memmap = populate_section_memmap(pfn, nr_pages, nid, altmap, pgmap);
862 if (!memmap) {
863 section_deactivate(pfn, nr_pages, altmap);
864 return ERR_PTR(error: -ENOMEM);
865 }
866
867 return memmap;
868}
869
870/**
871 * sparse_add_section - add a memory section, or populate an existing one
872 * @nid: The node to add section on
873 * @start_pfn: start pfn of the memory range
874 * @nr_pages: number of pfns to add in the section
875 * @altmap: alternate pfns to allocate the memmap backing store
876 * @pgmap: alternate compound page geometry for devmap mappings
877 *
878 * This is only intended for hotplug.
879 *
880 * Note that only VMEMMAP supports sub-section aligned hotplug,
881 * the proper alignment and size are gated by check_pfn_span().
882 *
883 *
884 * Return:
885 * * 0 - On success.
886 * * -EEXIST - Section has been present.
887 * * -ENOMEM - Out of memory.
888 */
889int __meminit sparse_add_section(int nid, unsigned long start_pfn,
890 unsigned long nr_pages, struct vmem_altmap *altmap,
891 struct dev_pagemap *pgmap)
892{
893 unsigned long section_nr = pfn_to_section_nr(pfn: start_pfn);
894 struct mem_section *ms;
895 struct page *memmap;
896 int ret;
897
898 ret = sparse_index_init(section_nr, nid);
899 if (ret < 0)
900 return ret;
901
902 memmap = section_activate(nid, pfn: start_pfn, nr_pages, altmap, pgmap);
903 if (IS_ERR(ptr: memmap))
904 return PTR_ERR(ptr: memmap);
905
906 /*
907 * Poison uninitialized struct pages in order to catch invalid flags
908 * combinations.
909 */
910 page_init_poison(page: memmap, size: sizeof(struct page) * nr_pages);
911
912 ms = __nr_to_section(nr: section_nr);
913 set_section_nid(section_nr, nid);
914 __section_mark_present(ms, section_nr);
915
916 /* Align memmap to section boundary in the subsection case */
917 if (section_nr_to_pfn(sec: section_nr) != start_pfn)
918 memmap = pfn_to_page(section_nr_to_pfn(section_nr));
919 sparse_init_one_section(ms, pnum: section_nr, mem_map: memmap, usage: ms->usage, flags: 0);
920
921 return 0;
922}
923
924void sparse_remove_section(unsigned long pfn, unsigned long nr_pages,
925 struct vmem_altmap *altmap)
926{
927 struct mem_section *ms = __pfn_to_section(pfn);
928
929 if (WARN_ON_ONCE(!valid_section(ms)))
930 return;
931
932 section_deactivate(pfn, nr_pages, altmap);
933}
934#endif /* CONFIG_MEMORY_HOTPLUG */
935

source code of linux/mm/sparse.c