858e1dff9b2af89b0c98203cd3e9099d8feffbbd
[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/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(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                 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 continuously.
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