radix-tree: use iterators in find_get_pages* functions
[linux-2.6.git] / mm / sparse.c
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/export.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(const 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                 usemap = alloc_bootmem_node(NODE_DATA(nodeid), size * usemap_count);
358                 if (!usemap) {
359                         printk(KERN_WARNING "%s: allocation failed\n", __func__);
360                         return;
361                 }
362         }
363
364         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
365                 if (!present_section_nr(pnum))
366                         continue;
367                 usemap_map[pnum] = usemap;
368                 usemap += size;
369                 check_usemap_section_nr(nodeid, usemap_map[pnum]);
370         }
371 }
372
373 #ifndef CONFIG_SPARSEMEM_VMEMMAP
374 struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid)
375 {
376         struct page *map;
377         unsigned long size;
378
379         map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
380         if (map)
381                 return map;
382
383         size = PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
384         map = __alloc_bootmem_node_high(NODE_DATA(nid), size,
385                                          PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
386         return map;
387 }
388 void __init sparse_mem_maps_populate_node(struct page **map_map,
389                                           unsigned long pnum_begin,
390                                           unsigned long pnum_end,
391                                           unsigned long map_count, int nodeid)
392 {
393         void *map;
394         unsigned long pnum;
395         unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
396
397         map = alloc_remap(nodeid, size * map_count);
398         if (map) {
399                 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
400                         if (!present_section_nr(pnum))
401                                 continue;
402                         map_map[pnum] = map;
403                         map += size;
404                 }
405                 return;
406         }
407
408         size = PAGE_ALIGN(size);
409         map = __alloc_bootmem_node_high(NODE_DATA(nodeid), size * map_count,
410                                          PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
411         if (map) {
412                 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
413                         if (!present_section_nr(pnum))
414                                 continue;
415                         map_map[pnum] = map;
416                         map += size;
417                 }
418                 return;
419         }
420
421         /* fallback */
422         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
423                 struct mem_section *ms;
424
425                 if (!present_section_nr(pnum))
426                         continue;
427                 map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
428                 if (map_map[pnum])
429                         continue;
430                 ms = __nr_to_section(pnum);
431                 printk(KERN_ERR "%s: sparsemem memory map backing failed "
432                         "some memory will not be available.\n", __func__);
433                 ms->section_mem_map = 0;
434         }
435 }
436 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
437
438 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
439 static void __init sparse_early_mem_maps_alloc_node(struct page **map_map,
440                                  unsigned long pnum_begin,
441                                  unsigned long pnum_end,
442                                  unsigned long map_count, int nodeid)
443 {
444         sparse_mem_maps_populate_node(map_map, pnum_begin, pnum_end,
445                                          map_count, nodeid);
446 }
447 #else
448 static struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
449 {
450         struct page *map;
451         struct mem_section *ms = __nr_to_section(pnum);
452         int nid = sparse_early_nid(ms);
453
454         map = sparse_mem_map_populate(pnum, nid);
455         if (map)
456                 return map;
457
458         printk(KERN_ERR "%s: sparsemem memory map backing failed "
459                         "some memory will not be available.\n", __func__);
460         ms->section_mem_map = 0;
461         return NULL;
462 }
463 #endif
464
465 void __attribute__((weak)) __meminit vmemmap_populate_print_last(void)
466 {
467 }
468
469 /*
470  * Allocate the accumulated non-linear sections, allocate a mem_map
471  * for each and record the physical to section mapping.
472  */
473 void __init sparse_init(void)
474 {
475         unsigned long pnum;
476         struct page *map;
477         unsigned long *usemap;
478         unsigned long **usemap_map;
479         int size;
480         int nodeid_begin = 0;
481         unsigned long pnum_begin = 0;
482         unsigned long usemap_count;
483 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
484         unsigned long map_count;
485         int size2;
486         struct page **map_map;
487 #endif
488
489         /*
490          * map is using big page (aka 2M in x86 64 bit)
491          * usemap is less one page (aka 24 bytes)
492          * so alloc 2M (with 2M align) and 24 bytes in turn will
493          * make next 2M slip to one more 2M later.
494          * then in big system, the memory will have a lot of holes...
495          * here try to allocate 2M pages continuously.
496          *
497          * powerpc need to call sparse_init_one_section right after each
498          * sparse_early_mem_map_alloc, so allocate usemap_map at first.
499          */
500         size = sizeof(unsigned long *) * NR_MEM_SECTIONS;
501         usemap_map = alloc_bootmem(size);
502         if (!usemap_map)
503                 panic("can not allocate usemap_map\n");
504
505         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
506                 struct mem_section *ms;
507
508                 if (!present_section_nr(pnum))
509                         continue;
510                 ms = __nr_to_section(pnum);
511                 nodeid_begin = sparse_early_nid(ms);
512                 pnum_begin = pnum;
513                 break;
514         }
515         usemap_count = 1;
516         for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
517                 struct mem_section *ms;
518                 int nodeid;
519
520                 if (!present_section_nr(pnum))
521                         continue;
522                 ms = __nr_to_section(pnum);
523                 nodeid = sparse_early_nid(ms);
524                 if (nodeid == nodeid_begin) {
525                         usemap_count++;
526                         continue;
527                 }
528                 /* ok, we need to take cake of from pnum_begin to pnum - 1*/
529                 sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, pnum,
530                                                  usemap_count, nodeid_begin);
531                 /* new start, update count etc*/
532                 nodeid_begin = nodeid;
533                 pnum_begin = pnum;
534                 usemap_count = 1;
535         }
536         /* ok, last chunk */
537         sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, NR_MEM_SECTIONS,
538                                          usemap_count, nodeid_begin);
539
540 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
541         size2 = sizeof(struct page *) * NR_MEM_SECTIONS;
542         map_map = alloc_bootmem(size2);
543         if (!map_map)
544                 panic("can not allocate map_map\n");
545
546         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
547                 struct mem_section *ms;
548
549                 if (!present_section_nr(pnum))
550                         continue;
551                 ms = __nr_to_section(pnum);
552                 nodeid_begin = sparse_early_nid(ms);
553                 pnum_begin = pnum;
554                 break;
555         }
556         map_count = 1;
557         for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
558                 struct mem_section *ms;
559                 int nodeid;
560
561                 if (!present_section_nr(pnum))
562                         continue;
563                 ms = __nr_to_section(pnum);
564                 nodeid = sparse_early_nid(ms);
565                 if (nodeid == nodeid_begin) {
566                         map_count++;
567                         continue;
568                 }
569                 /* ok, we need to take cake of from pnum_begin to pnum - 1*/
570                 sparse_early_mem_maps_alloc_node(map_map, pnum_begin, pnum,
571                                                  map_count, nodeid_begin);
572                 /* new start, update count etc*/
573                 nodeid_begin = nodeid;
574                 pnum_begin = pnum;
575                 map_count = 1;
576         }
577         /* ok, last chunk */
578         sparse_early_mem_maps_alloc_node(map_map, pnum_begin, NR_MEM_SECTIONS,
579                                          map_count, nodeid_begin);
580 #endif
581
582         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
583                 if (!present_section_nr(pnum))
584                         continue;
585
586                 usemap = usemap_map[pnum];
587                 if (!usemap)
588                         continue;
589
590 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
591                 map = map_map[pnum];
592 #else
593                 map = sparse_early_mem_map_alloc(pnum);
594 #endif
595                 if (!map)
596                         continue;
597
598                 sparse_init_one_section(__nr_to_section(pnum), pnum, map,
599                                                                 usemap);
600         }
601
602         vmemmap_populate_print_last();
603
604 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
605         free_bootmem(__pa(map_map), size2);
606 #endif
607         free_bootmem(__pa(usemap_map), size);
608 }
609
610 #ifdef CONFIG_MEMORY_HOTPLUG
611 #ifdef CONFIG_SPARSEMEM_VMEMMAP
612 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
613                                                  unsigned long nr_pages)
614 {
615         /* This will make the necessary allocations eventually. */
616         return sparse_mem_map_populate(pnum, nid);
617 }
618 static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
619 {
620         return; /* XXX: Not implemented yet */
621 }
622 static void free_map_bootmem(struct page *page, unsigned long nr_pages)
623 {
624 }
625 #else
626 static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
627 {
628         struct page *page, *ret;
629         unsigned long memmap_size = sizeof(struct page) * nr_pages;
630
631         page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
632         if (page)
633                 goto got_map_page;
634
635         ret = vmalloc(memmap_size);
636         if (ret)
637                 goto got_map_ptr;
638
639         return NULL;
640 got_map_page:
641         ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
642 got_map_ptr:
643         memset(ret, 0, memmap_size);
644
645         return ret;
646 }
647
648 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
649                                                   unsigned long nr_pages)
650 {
651         return __kmalloc_section_memmap(nr_pages);
652 }
653
654 static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
655 {
656         if (is_vmalloc_addr(memmap))
657                 vfree(memmap);
658         else
659                 free_pages((unsigned long)memmap,
660                            get_order(sizeof(struct page) * nr_pages));
661 }
662
663 static void free_map_bootmem(struct page *page, unsigned long nr_pages)
664 {
665         unsigned long maps_section_nr, removing_section_nr, i;
666         unsigned long magic;
667
668         for (i = 0; i < nr_pages; i++, page++) {
669                 magic = (unsigned long) page->lru.next;
670
671                 BUG_ON(magic == NODE_INFO);
672
673                 maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
674                 removing_section_nr = page->private;
675
676                 /*
677                  * When this function is called, the removing section is
678                  * logical offlined state. This means all pages are isolated
679                  * from page allocator. If removing section's memmap is placed
680                  * on the same section, it must not be freed.
681                  * If it is freed, page allocator may allocate it which will
682                  * be removed physically soon.
683                  */
684                 if (maps_section_nr != removing_section_nr)
685                         put_page_bootmem(page);
686         }
687 }
688 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
689
690 static void free_section_usemap(struct page *memmap, unsigned long *usemap)
691 {
692         struct page *usemap_page;
693         unsigned long nr_pages;
694
695         if (!usemap)
696                 return;
697
698         usemap_page = virt_to_page(usemap);
699         /*
700          * Check to see if allocation came from hot-plug-add
701          */
702         if (PageSlab(usemap_page)) {
703                 kfree(usemap);
704                 if (memmap)
705                         __kfree_section_memmap(memmap, PAGES_PER_SECTION);
706                 return;
707         }
708
709         /*
710          * The usemap came from bootmem. This is packed with other usemaps
711          * on the section which has pgdat at boot time. Just keep it as is now.
712          */
713
714         if (memmap) {
715                 struct page *memmap_page;
716                 memmap_page = virt_to_page(memmap);
717
718                 nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
719                         >> PAGE_SHIFT;
720
721                 free_map_bootmem(memmap_page, nr_pages);
722         }
723 }
724
725 /*
726  * returns the number of sections whose mem_maps were properly
727  * set.  If this is <=0, then that means that the passed-in
728  * map was not consumed and must be freed.
729  */
730 int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
731                            int nr_pages)
732 {
733         unsigned long section_nr = pfn_to_section_nr(start_pfn);
734         struct pglist_data *pgdat = zone->zone_pgdat;
735         struct mem_section *ms;
736         struct page *memmap;
737         unsigned long *usemap;
738         unsigned long flags;
739         int ret;
740
741         /*
742          * no locking for this, because it does its own
743          * plus, it does a kmalloc
744          */
745         ret = sparse_index_init(section_nr, pgdat->node_id);
746         if (ret < 0 && ret != -EEXIST)
747                 return ret;
748         memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, nr_pages);
749         if (!memmap)
750                 return -ENOMEM;
751         usemap = __kmalloc_section_usemap();
752         if (!usemap) {
753                 __kfree_section_memmap(memmap, nr_pages);
754                 return -ENOMEM;
755         }
756
757         pgdat_resize_lock(pgdat, &flags);
758
759         ms = __pfn_to_section(start_pfn);
760         if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
761                 ret = -EEXIST;
762                 goto out;
763         }
764
765         ms->section_mem_map |= SECTION_MARKED_PRESENT;
766
767         ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
768
769 out:
770         pgdat_resize_unlock(pgdat, &flags);
771         if (ret <= 0) {
772                 kfree(usemap);
773                 __kfree_section_memmap(memmap, nr_pages);
774         }
775         return ret;
776 }
777
778 void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
779 {
780         struct page *memmap = NULL;
781         unsigned long *usemap = NULL;
782
783         if (ms->section_mem_map) {
784                 usemap = ms->pageblock_flags;
785                 memmap = sparse_decode_mem_map(ms->section_mem_map,
786                                                 __section_nr(ms));
787                 ms->section_mem_map = 0;
788                 ms->pageblock_flags = NULL;
789         }
790
791         free_section_usemap(memmap, usemap);
792 }
793 #endif