xref: /openbmc/linux/mm/sparse.c (revision 4800cd83)
1 /*
2  * sparse memory mappings.
3  */
4 #include <linux/mm.h>
5 #include <linux/slab.h>
6 #include <linux/mmzone.h>
7 #include <linux/bootmem.h>
8 #include <linux/highmem.h>
9 #include <linux/module.h>
10 #include <linux/spinlock.h>
11 #include <linux/vmalloc.h>
12 #include "internal.h"
13 #include <asm/dma.h>
14 #include <asm/pgalloc.h>
15 #include <asm/pgtable.h>
16 
17 /*
18  * Permanent SPARSEMEM data:
19  *
20  * 1) mem_section	- memory sections, mem_map's for valid memory
21  */
22 #ifdef CONFIG_SPARSEMEM_EXTREME
23 struct mem_section *mem_section[NR_SECTION_ROOTS]
24 	____cacheline_internodealigned_in_smp;
25 #else
26 struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
27 	____cacheline_internodealigned_in_smp;
28 #endif
29 EXPORT_SYMBOL(mem_section);
30 
31 #ifdef NODE_NOT_IN_PAGE_FLAGS
32 /*
33  * If we did not store the node number in the page then we have to
34  * do a lookup in the section_to_node_table in order to find which
35  * node the page belongs to.
36  */
37 #if MAX_NUMNODES <= 256
38 static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
39 #else
40 static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
41 #endif
42 
43 int page_to_nid(struct page *page)
44 {
45 	return section_to_node_table[page_to_section(page)];
46 }
47 EXPORT_SYMBOL(page_to_nid);
48 
49 static void set_section_nid(unsigned long section_nr, int nid)
50 {
51 	section_to_node_table[section_nr] = nid;
52 }
53 #else /* !NODE_NOT_IN_PAGE_FLAGS */
54 static inline void set_section_nid(unsigned long section_nr, int nid)
55 {
56 }
57 #endif
58 
59 #ifdef CONFIG_SPARSEMEM_EXTREME
60 static struct mem_section noinline __init_refok *sparse_index_alloc(int nid)
61 {
62 	struct mem_section *section = NULL;
63 	unsigned long array_size = SECTIONS_PER_ROOT *
64 				   sizeof(struct mem_section);
65 
66 	if (slab_is_available()) {
67 		if (node_state(nid, N_HIGH_MEMORY))
68 			section = kmalloc_node(array_size, GFP_KERNEL, nid);
69 		else
70 			section = kmalloc(array_size, GFP_KERNEL);
71 	} else
72 		section = alloc_bootmem_node(NODE_DATA(nid), array_size);
73 
74 	if (section)
75 		memset(section, 0, array_size);
76 
77 	return section;
78 }
79 
80 static int __meminit sparse_index_init(unsigned long section_nr, int nid)
81 {
82 	static DEFINE_SPINLOCK(index_init_lock);
83 	unsigned long root = SECTION_NR_TO_ROOT(section_nr);
84 	struct mem_section *section;
85 	int ret = 0;
86 
87 	if (mem_section[root])
88 		return -EEXIST;
89 
90 	section = sparse_index_alloc(nid);
91 	if (!section)
92 		return -ENOMEM;
93 	/*
94 	 * This lock keeps two different sections from
95 	 * reallocating for the same index
96 	 */
97 	spin_lock(&index_init_lock);
98 
99 	if (mem_section[root]) {
100 		ret = -EEXIST;
101 		goto out;
102 	}
103 
104 	mem_section[root] = section;
105 out:
106 	spin_unlock(&index_init_lock);
107 	return ret;
108 }
109 #else /* !SPARSEMEM_EXTREME */
110 static inline int sparse_index_init(unsigned long section_nr, int nid)
111 {
112 	return 0;
113 }
114 #endif
115 
116 /*
117  * Although written for the SPARSEMEM_EXTREME case, this happens
118  * to also work for the flat array case because
119  * NR_SECTION_ROOTS==NR_MEM_SECTIONS.
120  */
121 int __section_nr(struct mem_section* ms)
122 {
123 	unsigned long root_nr;
124 	struct mem_section* root;
125 
126 	for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
127 		root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
128 		if (!root)
129 			continue;
130 
131 		if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
132 		     break;
133 	}
134 
135 	return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
136 }
137 
138 /*
139  * During early boot, before section_mem_map is used for an actual
140  * mem_map, we use section_mem_map to store the section's NUMA
141  * node.  This keeps us from having to use another data structure.  The
142  * node information is cleared just before we store the real mem_map.
143  */
144 static inline unsigned long sparse_encode_early_nid(int nid)
145 {
146 	return (nid << SECTION_NID_SHIFT);
147 }
148 
149 static inline int sparse_early_nid(struct mem_section *section)
150 {
151 	return (section->section_mem_map >> SECTION_NID_SHIFT);
152 }
153 
154 /* Validate the physical addressing limitations of the model */
155 void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
156 						unsigned long *end_pfn)
157 {
158 	unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
159 
160 	/*
161 	 * Sanity checks - do not allow an architecture to pass
162 	 * in larger pfns than the maximum scope of sparsemem:
163 	 */
164 	if (*start_pfn > max_sparsemem_pfn) {
165 		mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
166 			"Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
167 			*start_pfn, *end_pfn, max_sparsemem_pfn);
168 		WARN_ON_ONCE(1);
169 		*start_pfn = max_sparsemem_pfn;
170 		*end_pfn = max_sparsemem_pfn;
171 	} else if (*end_pfn > max_sparsemem_pfn) {
172 		mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
173 			"End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
174 			*start_pfn, *end_pfn, max_sparsemem_pfn);
175 		WARN_ON_ONCE(1);
176 		*end_pfn = max_sparsemem_pfn;
177 	}
178 }
179 
180 /* Record a memory area against a node. */
181 void __init memory_present(int nid, unsigned long start, unsigned long end)
182 {
183 	unsigned long pfn;
184 
185 	start &= PAGE_SECTION_MASK;
186 	mminit_validate_memmodel_limits(&start, &end);
187 	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
188 		unsigned long section = pfn_to_section_nr(pfn);
189 		struct mem_section *ms;
190 
191 		sparse_index_init(section, nid);
192 		set_section_nid(section, nid);
193 
194 		ms = __nr_to_section(section);
195 		if (!ms->section_mem_map)
196 			ms->section_mem_map = sparse_encode_early_nid(nid) |
197 							SECTION_MARKED_PRESENT;
198 	}
199 }
200 
201 /*
202  * Only used by the i386 NUMA architecures, but relatively
203  * generic code.
204  */
205 unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
206 						     unsigned long end_pfn)
207 {
208 	unsigned long pfn;
209 	unsigned long nr_pages = 0;
210 
211 	mminit_validate_memmodel_limits(&start_pfn, &end_pfn);
212 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
213 		if (nid != early_pfn_to_nid(pfn))
214 			continue;
215 
216 		if (pfn_present(pfn))
217 			nr_pages += PAGES_PER_SECTION;
218 	}
219 
220 	return nr_pages * sizeof(struct page);
221 }
222 
223 /*
224  * Subtle, we encode the real pfn into the mem_map such that
225  * the identity pfn - section_mem_map will return the actual
226  * physical page frame number.
227  */
228 static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
229 {
230 	return (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
231 }
232 
233 /*
234  * Decode mem_map from the coded memmap
235  */
236 struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
237 {
238 	/* mask off the extra low bits of information */
239 	coded_mem_map &= SECTION_MAP_MASK;
240 	return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
241 }
242 
243 static int __meminit sparse_init_one_section(struct mem_section *ms,
244 		unsigned long pnum, struct page *mem_map,
245 		unsigned long *pageblock_bitmap)
246 {
247 	if (!present_section(ms))
248 		return -EINVAL;
249 
250 	ms->section_mem_map &= ~SECTION_MAP_MASK;
251 	ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
252 							SECTION_HAS_MEM_MAP;
253  	ms->pageblock_flags = pageblock_bitmap;
254 
255 	return 1;
256 }
257 
258 unsigned long usemap_size(void)
259 {
260 	unsigned long size_bytes;
261 	size_bytes = roundup(SECTION_BLOCKFLAGS_BITS, 8) / 8;
262 	size_bytes = roundup(size_bytes, sizeof(unsigned long));
263 	return size_bytes;
264 }
265 
266 #ifdef CONFIG_MEMORY_HOTPLUG
267 static unsigned long *__kmalloc_section_usemap(void)
268 {
269 	return kmalloc(usemap_size(), GFP_KERNEL);
270 }
271 #endif /* CONFIG_MEMORY_HOTPLUG */
272 
273 #ifdef CONFIG_MEMORY_HOTREMOVE
274 static unsigned long * __init
275 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
276 					 unsigned long count)
277 {
278 	unsigned long section_nr;
279 
280 	/*
281 	 * A page may contain usemaps for other sections preventing the
282 	 * page being freed and making a section unremovable while
283 	 * other sections referencing the usemap retmain active. Similarly,
284 	 * a pgdat can prevent a section being removed. If section A
285 	 * contains a pgdat and section B contains the usemap, both
286 	 * sections become inter-dependent. This allocates usemaps
287 	 * from the same section as the pgdat where possible to avoid
288 	 * this problem.
289 	 */
290 	section_nr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
291 	return alloc_bootmem_section(usemap_size() * count, section_nr);
292 }
293 
294 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
295 {
296 	unsigned long usemap_snr, pgdat_snr;
297 	static unsigned long old_usemap_snr = NR_MEM_SECTIONS;
298 	static unsigned long old_pgdat_snr = NR_MEM_SECTIONS;
299 	struct pglist_data *pgdat = NODE_DATA(nid);
300 	int usemap_nid;
301 
302 	usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
303 	pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
304 	if (usemap_snr == pgdat_snr)
305 		return;
306 
307 	if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
308 		/* skip redundant message */
309 		return;
310 
311 	old_usemap_snr = usemap_snr;
312 	old_pgdat_snr = pgdat_snr;
313 
314 	usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
315 	if (usemap_nid != nid) {
316 		printk(KERN_INFO
317 		       "node %d must be removed before remove section %ld\n",
318 		       nid, usemap_snr);
319 		return;
320 	}
321 	/*
322 	 * There is a circular dependency.
323 	 * Some platforms allow un-removable section because they will just
324 	 * gather other removable sections for dynamic partitioning.
325 	 * Just notify un-removable section's number here.
326 	 */
327 	printk(KERN_INFO "Section %ld and %ld (node %d)", usemap_snr,
328 	       pgdat_snr, nid);
329 	printk(KERN_CONT
330 	       " have a circular dependency on usemap and pgdat allocations\n");
331 }
332 #else
333 static unsigned long * __init
334 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
335 					 unsigned long count)
336 {
337 	return NULL;
338 }
339 
340 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
341 {
342 }
343 #endif /* CONFIG_MEMORY_HOTREMOVE */
344 
345 static void __init sparse_early_usemaps_alloc_node(unsigned long**usemap_map,
346 				 unsigned long pnum_begin,
347 				 unsigned long pnum_end,
348 				 unsigned long usemap_count, int nodeid)
349 {
350 	void *usemap;
351 	unsigned long pnum;
352 	int size = usemap_size();
353 
354 	usemap = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nodeid),
355 								 usemap_count);
356 	if (usemap) {
357 		for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
358 			if (!present_section_nr(pnum))
359 				continue;
360 			usemap_map[pnum] = usemap;
361 			usemap += size;
362 		}
363 		return;
364 	}
365 
366 	usemap = alloc_bootmem_node(NODE_DATA(nodeid), size * usemap_count);
367 	if (usemap) {
368 		for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
369 			if (!present_section_nr(pnum))
370 				continue;
371 			usemap_map[pnum] = usemap;
372 			usemap += size;
373 			check_usemap_section_nr(nodeid, usemap_map[pnum]);
374 		}
375 		return;
376 	}
377 
378 	printk(KERN_WARNING "%s: allocation failed\n", __func__);
379 }
380 
381 #ifndef CONFIG_SPARSEMEM_VMEMMAP
382 struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid)
383 {
384 	struct page *map;
385 	unsigned long size;
386 
387 	map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
388 	if (map)
389 		return map;
390 
391 	size = PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
392 	map = __alloc_bootmem_node_high(NODE_DATA(nid), size,
393 					 PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
394 	return map;
395 }
396 void __init sparse_mem_maps_populate_node(struct page **map_map,
397 					  unsigned long pnum_begin,
398 					  unsigned long pnum_end,
399 					  unsigned long map_count, int nodeid)
400 {
401 	void *map;
402 	unsigned long pnum;
403 	unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
404 
405 	map = alloc_remap(nodeid, size * map_count);
406 	if (map) {
407 		for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
408 			if (!present_section_nr(pnum))
409 				continue;
410 			map_map[pnum] = map;
411 			map += size;
412 		}
413 		return;
414 	}
415 
416 	size = PAGE_ALIGN(size);
417 	map = __alloc_bootmem_node_high(NODE_DATA(nodeid), size * map_count,
418 					 PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
419 	if (map) {
420 		for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
421 			if (!present_section_nr(pnum))
422 				continue;
423 			map_map[pnum] = map;
424 			map += size;
425 		}
426 		return;
427 	}
428 
429 	/* fallback */
430 	for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
431 		struct mem_section *ms;
432 
433 		if (!present_section_nr(pnum))
434 			continue;
435 		map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
436 		if (map_map[pnum])
437 			continue;
438 		ms = __nr_to_section(pnum);
439 		printk(KERN_ERR "%s: sparsemem memory map backing failed "
440 			"some memory will not be available.\n", __func__);
441 		ms->section_mem_map = 0;
442 	}
443 }
444 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
445 
446 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
447 static void __init sparse_early_mem_maps_alloc_node(struct page **map_map,
448 				 unsigned long pnum_begin,
449 				 unsigned long pnum_end,
450 				 unsigned long map_count, int nodeid)
451 {
452 	sparse_mem_maps_populate_node(map_map, pnum_begin, pnum_end,
453 					 map_count, nodeid);
454 }
455 #else
456 static struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
457 {
458 	struct page *map;
459 	struct mem_section *ms = __nr_to_section(pnum);
460 	int nid = sparse_early_nid(ms);
461 
462 	map = sparse_mem_map_populate(pnum, nid);
463 	if (map)
464 		return map;
465 
466 	printk(KERN_ERR "%s: sparsemem memory map backing failed "
467 			"some memory will not be available.\n", __func__);
468 	ms->section_mem_map = 0;
469 	return NULL;
470 }
471 #endif
472 
473 void __attribute__((weak)) __meminit vmemmap_populate_print_last(void)
474 {
475 }
476 
477 /*
478  * Allocate the accumulated non-linear sections, allocate a mem_map
479  * for each and record the physical to section mapping.
480  */
481 void __init sparse_init(void)
482 {
483 	unsigned long pnum;
484 	struct page *map;
485 	unsigned long *usemap;
486 	unsigned long **usemap_map;
487 	int size;
488 	int nodeid_begin = 0;
489 	unsigned long pnum_begin = 0;
490 	unsigned long usemap_count;
491 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
492 	unsigned long map_count;
493 	int size2;
494 	struct page **map_map;
495 #endif
496 
497 	/*
498 	 * map is using big page (aka 2M in x86 64 bit)
499 	 * usemap is less one page (aka 24 bytes)
500 	 * so alloc 2M (with 2M align) and 24 bytes in turn will
501 	 * make next 2M slip to one more 2M later.
502 	 * then in big system, the memory will have a lot of holes...
503 	 * here try to allocate 2M pages continously.
504 	 *
505 	 * powerpc need to call sparse_init_one_section right after each
506 	 * sparse_early_mem_map_alloc, so allocate usemap_map at first.
507 	 */
508 	size = sizeof(unsigned long *) * NR_MEM_SECTIONS;
509 	usemap_map = alloc_bootmem(size);
510 	if (!usemap_map)
511 		panic("can not allocate usemap_map\n");
512 
513 	for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
514 		struct mem_section *ms;
515 
516 		if (!present_section_nr(pnum))
517 			continue;
518 		ms = __nr_to_section(pnum);
519 		nodeid_begin = sparse_early_nid(ms);
520 		pnum_begin = pnum;
521 		break;
522 	}
523 	usemap_count = 1;
524 	for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
525 		struct mem_section *ms;
526 		int nodeid;
527 
528 		if (!present_section_nr(pnum))
529 			continue;
530 		ms = __nr_to_section(pnum);
531 		nodeid = sparse_early_nid(ms);
532 		if (nodeid == nodeid_begin) {
533 			usemap_count++;
534 			continue;
535 		}
536 		/* ok, we need to take cake of from pnum_begin to pnum - 1*/
537 		sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, pnum,
538 						 usemap_count, nodeid_begin);
539 		/* new start, update count etc*/
540 		nodeid_begin = nodeid;
541 		pnum_begin = pnum;
542 		usemap_count = 1;
543 	}
544 	/* ok, last chunk */
545 	sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, NR_MEM_SECTIONS,
546 					 usemap_count, nodeid_begin);
547 
548 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
549 	size2 = sizeof(struct page *) * NR_MEM_SECTIONS;
550 	map_map = alloc_bootmem(size2);
551 	if (!map_map)
552 		panic("can not allocate map_map\n");
553 
554 	for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
555 		struct mem_section *ms;
556 
557 		if (!present_section_nr(pnum))
558 			continue;
559 		ms = __nr_to_section(pnum);
560 		nodeid_begin = sparse_early_nid(ms);
561 		pnum_begin = pnum;
562 		break;
563 	}
564 	map_count = 1;
565 	for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
566 		struct mem_section *ms;
567 		int nodeid;
568 
569 		if (!present_section_nr(pnum))
570 			continue;
571 		ms = __nr_to_section(pnum);
572 		nodeid = sparse_early_nid(ms);
573 		if (nodeid == nodeid_begin) {
574 			map_count++;
575 			continue;
576 		}
577 		/* ok, we need to take cake of from pnum_begin to pnum - 1*/
578 		sparse_early_mem_maps_alloc_node(map_map, pnum_begin, pnum,
579 						 map_count, nodeid_begin);
580 		/* new start, update count etc*/
581 		nodeid_begin = nodeid;
582 		pnum_begin = pnum;
583 		map_count = 1;
584 	}
585 	/* ok, last chunk */
586 	sparse_early_mem_maps_alloc_node(map_map, pnum_begin, NR_MEM_SECTIONS,
587 					 map_count, nodeid_begin);
588 #endif
589 
590 	for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
591 		if (!present_section_nr(pnum))
592 			continue;
593 
594 		usemap = usemap_map[pnum];
595 		if (!usemap)
596 			continue;
597 
598 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
599 		map = map_map[pnum];
600 #else
601 		map = sparse_early_mem_map_alloc(pnum);
602 #endif
603 		if (!map)
604 			continue;
605 
606 		sparse_init_one_section(__nr_to_section(pnum), pnum, map,
607 								usemap);
608 	}
609 
610 	vmemmap_populate_print_last();
611 
612 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
613 	free_bootmem(__pa(map_map), size2);
614 #endif
615 	free_bootmem(__pa(usemap_map), size);
616 }
617 
618 #ifdef CONFIG_MEMORY_HOTPLUG
619 #ifdef CONFIG_SPARSEMEM_VMEMMAP
620 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
621 						 unsigned long nr_pages)
622 {
623 	/* This will make the necessary allocations eventually. */
624 	return sparse_mem_map_populate(pnum, nid);
625 }
626 static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
627 {
628 	return; /* XXX: Not implemented yet */
629 }
630 static void free_map_bootmem(struct page *page, unsigned long nr_pages)
631 {
632 }
633 #else
634 static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
635 {
636 	struct page *page, *ret;
637 	unsigned long memmap_size = sizeof(struct page) * nr_pages;
638 
639 	page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
640 	if (page)
641 		goto got_map_page;
642 
643 	ret = vmalloc(memmap_size);
644 	if (ret)
645 		goto got_map_ptr;
646 
647 	return NULL;
648 got_map_page:
649 	ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
650 got_map_ptr:
651 	memset(ret, 0, memmap_size);
652 
653 	return ret;
654 }
655 
656 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
657 						  unsigned long nr_pages)
658 {
659 	return __kmalloc_section_memmap(nr_pages);
660 }
661 
662 static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
663 {
664 	if (is_vmalloc_addr(memmap))
665 		vfree(memmap);
666 	else
667 		free_pages((unsigned long)memmap,
668 			   get_order(sizeof(struct page) * nr_pages));
669 }
670 
671 static void free_map_bootmem(struct page *page, unsigned long nr_pages)
672 {
673 	unsigned long maps_section_nr, removing_section_nr, i;
674 	unsigned long magic;
675 
676 	for (i = 0; i < nr_pages; i++, page++) {
677 		magic = (unsigned long) page->lru.next;
678 
679 		BUG_ON(magic == NODE_INFO);
680 
681 		maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
682 		removing_section_nr = page->private;
683 
684 		/*
685 		 * When this function is called, the removing section is
686 		 * logical offlined state. This means all pages are isolated
687 		 * from page allocator. If removing section's memmap is placed
688 		 * on the same section, it must not be freed.
689 		 * If it is freed, page allocator may allocate it which will
690 		 * be removed physically soon.
691 		 */
692 		if (maps_section_nr != removing_section_nr)
693 			put_page_bootmem(page);
694 	}
695 }
696 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
697 
698 static void free_section_usemap(struct page *memmap, unsigned long *usemap)
699 {
700 	struct page *usemap_page;
701 	unsigned long nr_pages;
702 
703 	if (!usemap)
704 		return;
705 
706 	usemap_page = virt_to_page(usemap);
707 	/*
708 	 * Check to see if allocation came from hot-plug-add
709 	 */
710 	if (PageSlab(usemap_page)) {
711 		kfree(usemap);
712 		if (memmap)
713 			__kfree_section_memmap(memmap, PAGES_PER_SECTION);
714 		return;
715 	}
716 
717 	/*
718 	 * The usemap came from bootmem. This is packed with other usemaps
719 	 * on the section which has pgdat at boot time. Just keep it as is now.
720 	 */
721 
722 	if (memmap) {
723 		struct page *memmap_page;
724 		memmap_page = virt_to_page(memmap);
725 
726 		nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
727 			>> PAGE_SHIFT;
728 
729 		free_map_bootmem(memmap_page, nr_pages);
730 	}
731 }
732 
733 /*
734  * returns the number of sections whose mem_maps were properly
735  * set.  If this is <=0, then that means that the passed-in
736  * map was not consumed and must be freed.
737  */
738 int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
739 			   int nr_pages)
740 {
741 	unsigned long section_nr = pfn_to_section_nr(start_pfn);
742 	struct pglist_data *pgdat = zone->zone_pgdat;
743 	struct mem_section *ms;
744 	struct page *memmap;
745 	unsigned long *usemap;
746 	unsigned long flags;
747 	int ret;
748 
749 	/*
750 	 * no locking for this, because it does its own
751 	 * plus, it does a kmalloc
752 	 */
753 	ret = sparse_index_init(section_nr, pgdat->node_id);
754 	if (ret < 0 && ret != -EEXIST)
755 		return ret;
756 	memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, nr_pages);
757 	if (!memmap)
758 		return -ENOMEM;
759 	usemap = __kmalloc_section_usemap();
760 	if (!usemap) {
761 		__kfree_section_memmap(memmap, nr_pages);
762 		return -ENOMEM;
763 	}
764 
765 	pgdat_resize_lock(pgdat, &flags);
766 
767 	ms = __pfn_to_section(start_pfn);
768 	if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
769 		ret = -EEXIST;
770 		goto out;
771 	}
772 
773 	ms->section_mem_map |= SECTION_MARKED_PRESENT;
774 
775 	ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
776 
777 out:
778 	pgdat_resize_unlock(pgdat, &flags);
779 	if (ret <= 0) {
780 		kfree(usemap);
781 		__kfree_section_memmap(memmap, nr_pages);
782 	}
783 	return ret;
784 }
785 
786 void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
787 {
788 	struct page *memmap = NULL;
789 	unsigned long *usemap = NULL;
790 
791 	if (ms->section_mem_map) {
792 		usemap = ms->pageblock_flags;
793 		memmap = sparse_decode_mem_map(ms->section_mem_map,
794 						__section_nr(ms));
795 		ms->section_mem_map = 0;
796 		ms->pageblock_flags = NULL;
797 	}
798 
799 	free_section_usemap(memmap, usemap);
800 }
801 #endif
802