mm: have order > 0 compaction start near a pageblock with free pages
[linux-3.10.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 = kzalloc_node(array_size, GFP_KERNEL, nid);
69                 else
70                         section = kzalloc(array_size, GFP_KERNEL);
71         } else {
72                 section = alloc_bootmem_node(NODE_DATA(nid), array_size);
73         }
74
75         return section;
76 }
77
78 static int __meminit sparse_index_init(unsigned long section_nr, int nid)
79 {
80         unsigned long root = SECTION_NR_TO_ROOT(section_nr);
81         struct mem_section *section;
82         int ret = 0;
83
84         if (mem_section[root])
85                 return -EEXIST;
86
87         section = sparse_index_alloc(nid);
88         if (!section)
89                 return -ENOMEM;
90
91         mem_section[root] = section;
92
93         return ret;
94 }
95 #else /* !SPARSEMEM_EXTREME */
96 static inline int sparse_index_init(unsigned long section_nr, int nid)
97 {
98         return 0;
99 }
100 #endif
101
102 /*
103  * Although written for the SPARSEMEM_EXTREME case, this happens
104  * to also work for the flat array case because
105  * NR_SECTION_ROOTS==NR_MEM_SECTIONS.
106  */
107 int __section_nr(struct mem_section* ms)
108 {
109         unsigned long root_nr;
110         struct mem_section* root;
111
112         for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
113                 root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
114                 if (!root)
115                         continue;
116
117                 if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
118                      break;
119         }
120
121         VM_BUG_ON(root_nr == NR_SECTION_ROOTS);
122
123         return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
124 }
125
126 /*
127  * During early boot, before section_mem_map is used for an actual
128  * mem_map, we use section_mem_map to store the section's NUMA
129  * node.  This keeps us from having to use another data structure.  The
130  * node information is cleared just before we store the real mem_map.
131  */
132 static inline unsigned long sparse_encode_early_nid(int nid)
133 {
134         return (nid << SECTION_NID_SHIFT);
135 }
136
137 static inline int sparse_early_nid(struct mem_section *section)
138 {
139         return (section->section_mem_map >> SECTION_NID_SHIFT);
140 }
141
142 /* Validate the physical addressing limitations of the model */
143 void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
144                                                 unsigned long *end_pfn)
145 {
146         unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
147
148         /*
149          * Sanity checks - do not allow an architecture to pass
150          * in larger pfns than the maximum scope of sparsemem:
151          */
152         if (*start_pfn > max_sparsemem_pfn) {
153                 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
154                         "Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
155                         *start_pfn, *end_pfn, max_sparsemem_pfn);
156                 WARN_ON_ONCE(1);
157                 *start_pfn = max_sparsemem_pfn;
158                 *end_pfn = max_sparsemem_pfn;
159         } else if (*end_pfn > max_sparsemem_pfn) {
160                 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
161                         "End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
162                         *start_pfn, *end_pfn, max_sparsemem_pfn);
163                 WARN_ON_ONCE(1);
164                 *end_pfn = max_sparsemem_pfn;
165         }
166 }
167
168 /* Record a memory area against a node. */
169 void __init memory_present(int nid, unsigned long start, unsigned long end)
170 {
171         unsigned long pfn;
172
173         start &= PAGE_SECTION_MASK;
174         mminit_validate_memmodel_limits(&start, &end);
175         for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
176                 unsigned long section = pfn_to_section_nr(pfn);
177                 struct mem_section *ms;
178
179                 sparse_index_init(section, nid);
180                 set_section_nid(section, nid);
181
182                 ms = __nr_to_section(section);
183                 if (!ms->section_mem_map)
184                         ms->section_mem_map = sparse_encode_early_nid(nid) |
185                                                         SECTION_MARKED_PRESENT;
186         }
187 }
188
189 /*
190  * Only used by the i386 NUMA architecures, but relatively
191  * generic code.
192  */
193 unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
194                                                      unsigned long end_pfn)
195 {
196         unsigned long pfn;
197         unsigned long nr_pages = 0;
198
199         mminit_validate_memmodel_limits(&start_pfn, &end_pfn);
200         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
201                 if (nid != early_pfn_to_nid(pfn))
202                         continue;
203
204                 if (pfn_present(pfn))
205                         nr_pages += PAGES_PER_SECTION;
206         }
207
208         return nr_pages * sizeof(struct page);
209 }
210
211 /*
212  * Subtle, we encode the real pfn into the mem_map such that
213  * the identity pfn - section_mem_map will return the actual
214  * physical page frame number.
215  */
216 static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
217 {
218         return (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
219 }
220
221 /*
222  * Decode mem_map from the coded memmap
223  */
224 struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
225 {
226         /* mask off the extra low bits of information */
227         coded_mem_map &= SECTION_MAP_MASK;
228         return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
229 }
230
231 static int __meminit sparse_init_one_section(struct mem_section *ms,
232                 unsigned long pnum, struct page *mem_map,
233                 unsigned long *pageblock_bitmap)
234 {
235         if (!present_section(ms))
236                 return -EINVAL;
237
238         ms->section_mem_map &= ~SECTION_MAP_MASK;
239         ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
240                                                         SECTION_HAS_MEM_MAP;
241         ms->pageblock_flags = pageblock_bitmap;
242
243         return 1;
244 }
245
246 unsigned long usemap_size(void)
247 {
248         unsigned long size_bytes;
249         size_bytes = roundup(SECTION_BLOCKFLAGS_BITS, 8) / 8;
250         size_bytes = roundup(size_bytes, sizeof(unsigned long));
251         return size_bytes;
252 }
253
254 #ifdef CONFIG_MEMORY_HOTPLUG
255 static unsigned long *__kmalloc_section_usemap(void)
256 {
257         return kmalloc(usemap_size(), GFP_KERNEL);
258 }
259 #endif /* CONFIG_MEMORY_HOTPLUG */
260
261 #ifdef CONFIG_MEMORY_HOTREMOVE
262 static unsigned long * __init
263 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
264                                          unsigned long size)
265 {
266         unsigned long goal, limit;
267         unsigned long *p;
268         int nid;
269         /*
270          * A page may contain usemaps for other sections preventing the
271          * page being freed and making a section unremovable while
272          * other sections referencing the usemap retmain active. Similarly,
273          * a pgdat can prevent a section being removed. If section A
274          * contains a pgdat and section B contains the usemap, both
275          * sections become inter-dependent. This allocates usemaps
276          * from the same section as the pgdat where possible to avoid
277          * this problem.
278          */
279         goal = __pa(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
280         limit = goal + (1UL << PA_SECTION_SHIFT);
281         nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
282 again:
283         p = ___alloc_bootmem_node_nopanic(NODE_DATA(nid), size,
284                                           SMP_CACHE_BYTES, goal, limit);
285         if (!p && limit) {
286                 limit = 0;
287                 goto again;
288         }
289         return p;
290 }
291
292 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
293 {
294         unsigned long usemap_snr, pgdat_snr;
295         static unsigned long old_usemap_snr = NR_MEM_SECTIONS;
296         static unsigned long old_pgdat_snr = NR_MEM_SECTIONS;
297         struct pglist_data *pgdat = NODE_DATA(nid);
298         int usemap_nid;
299
300         usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
301         pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
302         if (usemap_snr == pgdat_snr)
303                 return;
304
305         if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
306                 /* skip redundant message */
307                 return;
308
309         old_usemap_snr = usemap_snr;
310         old_pgdat_snr = pgdat_snr;
311
312         usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
313         if (usemap_nid != nid) {
314                 printk(KERN_INFO
315                        "node %d must be removed before remove section %ld\n",
316                        nid, usemap_snr);
317                 return;
318         }
319         /*
320          * There is a circular dependency.
321          * Some platforms allow un-removable section because they will just
322          * gather other removable sections for dynamic partitioning.
323          * Just notify un-removable section's number here.
324          */
325         printk(KERN_INFO "Section %ld and %ld (node %d)", usemap_snr,
326                pgdat_snr, nid);
327         printk(KERN_CONT
328                " have a circular dependency on usemap and pgdat allocations\n");
329 }
330 #else
331 static unsigned long * __init
332 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
333                                          unsigned long size)
334 {
335         return alloc_bootmem_node_nopanic(pgdat, size);
336 }
337
338 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
339 {
340 }
341 #endif /* CONFIG_MEMORY_HOTREMOVE */
342
343 static void __init sparse_early_usemaps_alloc_node(unsigned long**usemap_map,
344                                  unsigned long pnum_begin,
345                                  unsigned long pnum_end,
346                                  unsigned long usemap_count, int nodeid)
347 {
348         void *usemap;
349         unsigned long pnum;
350         int size = usemap_size();
351
352         usemap = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nodeid),
353                                                           size * usemap_count);
354         if (!usemap) {
355                 printk(KERN_WARNING "%s: allocation failed\n", __func__);
356                 return;
357         }
358
359         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
360                 if (!present_section_nr(pnum))
361                         continue;
362                 usemap_map[pnum] = usemap;
363                 usemap += size;
364                 check_usemap_section_nr(nodeid, usemap_map[pnum]);
365         }
366 }
367
368 #ifndef CONFIG_SPARSEMEM_VMEMMAP
369 struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid)
370 {
371         struct page *map;
372         unsigned long size;
373
374         map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
375         if (map)
376                 return map;
377
378         size = PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
379         map = __alloc_bootmem_node_high(NODE_DATA(nid), size,
380                                          PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
381         return map;
382 }
383 void __init sparse_mem_maps_populate_node(struct page **map_map,
384                                           unsigned long pnum_begin,
385                                           unsigned long pnum_end,
386                                           unsigned long map_count, int nodeid)
387 {
388         void *map;
389         unsigned long pnum;
390         unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
391
392         map = alloc_remap(nodeid, size * map_count);
393         if (map) {
394                 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
395                         if (!present_section_nr(pnum))
396                                 continue;
397                         map_map[pnum] = map;
398                         map += size;
399                 }
400                 return;
401         }
402
403         size = PAGE_ALIGN(size);
404         map = __alloc_bootmem_node_high(NODE_DATA(nodeid), size * map_count,
405                                          PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
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         /* fallback */
417         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
418                 struct mem_section *ms;
419
420                 if (!present_section_nr(pnum))
421                         continue;
422                 map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
423                 if (map_map[pnum])
424                         continue;
425                 ms = __nr_to_section(pnum);
426                 printk(KERN_ERR "%s: sparsemem memory map backing failed "
427                         "some memory will not be available.\n", __func__);
428                 ms->section_mem_map = 0;
429         }
430 }
431 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
432
433 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
434 static void __init sparse_early_mem_maps_alloc_node(struct page **map_map,
435                                  unsigned long pnum_begin,
436                                  unsigned long pnum_end,
437                                  unsigned long map_count, int nodeid)
438 {
439         sparse_mem_maps_populate_node(map_map, pnum_begin, pnum_end,
440                                          map_count, nodeid);
441 }
442 #else
443 static struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
444 {
445         struct page *map;
446         struct mem_section *ms = __nr_to_section(pnum);
447         int nid = sparse_early_nid(ms);
448
449         map = sparse_mem_map_populate(pnum, nid);
450         if (map)
451                 return map;
452
453         printk(KERN_ERR "%s: sparsemem memory map backing failed "
454                         "some memory will not be available.\n", __func__);
455         ms->section_mem_map = 0;
456         return NULL;
457 }
458 #endif
459
460 void __attribute__((weak)) __meminit vmemmap_populate_print_last(void)
461 {
462 }
463
464 /*
465  * Allocate the accumulated non-linear sections, allocate a mem_map
466  * for each and record the physical to section mapping.
467  */
468 void __init sparse_init(void)
469 {
470         unsigned long pnum;
471         struct page *map;
472         unsigned long *usemap;
473         unsigned long **usemap_map;
474         int size;
475         int nodeid_begin = 0;
476         unsigned long pnum_begin = 0;
477         unsigned long usemap_count;
478 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
479         unsigned long map_count;
480         int size2;
481         struct page **map_map;
482 #endif
483
484         /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
485         set_pageblock_order();
486
487         /*
488          * map is using big page (aka 2M in x86 64 bit)
489          * usemap is less one page (aka 24 bytes)
490          * so alloc 2M (with 2M align) and 24 bytes in turn will
491          * make next 2M slip to one more 2M later.
492          * then in big system, the memory will have a lot of holes...
493          * here try to allocate 2M pages continuously.
494          *
495          * powerpc need to call sparse_init_one_section right after each
496          * sparse_early_mem_map_alloc, so allocate usemap_map at first.
497          */
498         size = sizeof(unsigned long *) * NR_MEM_SECTIONS;
499         usemap_map = alloc_bootmem(size);
500         if (!usemap_map)
501                 panic("can not allocate usemap_map\n");
502
503         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
504                 struct mem_section *ms;
505
506                 if (!present_section_nr(pnum))
507                         continue;
508                 ms = __nr_to_section(pnum);
509                 nodeid_begin = sparse_early_nid(ms);
510                 pnum_begin = pnum;
511                 break;
512         }
513         usemap_count = 1;
514         for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
515                 struct mem_section *ms;
516                 int nodeid;
517
518                 if (!present_section_nr(pnum))
519                         continue;
520                 ms = __nr_to_section(pnum);
521                 nodeid = sparse_early_nid(ms);
522                 if (nodeid == nodeid_begin) {
523                         usemap_count++;
524                         continue;
525                 }
526                 /* ok, we need to take cake of from pnum_begin to pnum - 1*/
527                 sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, pnum,
528                                                  usemap_count, nodeid_begin);
529                 /* new start, update count etc*/
530                 nodeid_begin = nodeid;
531                 pnum_begin = pnum;
532                 usemap_count = 1;
533         }
534         /* ok, last chunk */
535         sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, NR_MEM_SECTIONS,
536                                          usemap_count, nodeid_begin);
537
538 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
539         size2 = sizeof(struct page *) * NR_MEM_SECTIONS;
540         map_map = alloc_bootmem(size2);
541         if (!map_map)
542                 panic("can not allocate map_map\n");
543
544         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
545                 struct mem_section *ms;
546
547                 if (!present_section_nr(pnum))
548                         continue;
549                 ms = __nr_to_section(pnum);
550                 nodeid_begin = sparse_early_nid(ms);
551                 pnum_begin = pnum;
552                 break;
553         }
554         map_count = 1;
555         for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
556                 struct mem_section *ms;
557                 int nodeid;
558
559                 if (!present_section_nr(pnum))
560                         continue;
561                 ms = __nr_to_section(pnum);
562                 nodeid = sparse_early_nid(ms);
563                 if (nodeid == nodeid_begin) {
564                         map_count++;
565                         continue;
566                 }
567                 /* ok, we need to take cake of from pnum_begin to pnum - 1*/
568                 sparse_early_mem_maps_alloc_node(map_map, pnum_begin, pnum,
569                                                  map_count, nodeid_begin);
570                 /* new start, update count etc*/
571                 nodeid_begin = nodeid;
572                 pnum_begin = pnum;
573                 map_count = 1;
574         }
575         /* ok, last chunk */
576         sparse_early_mem_maps_alloc_node(map_map, pnum_begin, NR_MEM_SECTIONS,
577                                          map_count, nodeid_begin);
578 #endif
579
580         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
581                 if (!present_section_nr(pnum))
582                         continue;
583
584                 usemap = usemap_map[pnum];
585                 if (!usemap)
586                         continue;
587
588 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
589                 map = map_map[pnum];
590 #else
591                 map = sparse_early_mem_map_alloc(pnum);
592 #endif
593                 if (!map)
594                         continue;
595
596                 sparse_init_one_section(__nr_to_section(pnum), pnum, map,
597                                                                 usemap);
598         }
599
600         vmemmap_populate_print_last();
601
602 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
603         free_bootmem(__pa(map_map), size2);
604 #endif
605         free_bootmem(__pa(usemap_map), size);
606 }
607
608 #ifdef CONFIG_MEMORY_HOTPLUG
609 #ifdef CONFIG_SPARSEMEM_VMEMMAP
610 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
611                                                  unsigned long nr_pages)
612 {
613         /* This will make the necessary allocations eventually. */
614         return sparse_mem_map_populate(pnum, nid);
615 }
616 static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
617 {
618         return; /* XXX: Not implemented yet */
619 }
620 static void free_map_bootmem(struct page *page, unsigned long nr_pages)
621 {
622 }
623 #else
624 static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
625 {
626         struct page *page, *ret;
627         unsigned long memmap_size = sizeof(struct page) * nr_pages;
628
629         page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
630         if (page)
631                 goto got_map_page;
632
633         ret = vmalloc(memmap_size);
634         if (ret)
635                 goto got_map_ptr;
636
637         return NULL;
638 got_map_page:
639         ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
640 got_map_ptr:
641         memset(ret, 0, memmap_size);
642
643         return ret;
644 }
645
646 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
647                                                   unsigned long nr_pages)
648 {
649         return __kmalloc_section_memmap(nr_pages);
650 }
651
652 static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
653 {
654         if (is_vmalloc_addr(memmap))
655                 vfree(memmap);
656         else
657                 free_pages((unsigned long)memmap,
658                            get_order(sizeof(struct page) * nr_pages));
659 }
660
661 static void free_map_bootmem(struct page *page, unsigned long nr_pages)
662 {
663         unsigned long maps_section_nr, removing_section_nr, i;
664         unsigned long magic;
665
666         for (i = 0; i < nr_pages; i++, page++) {
667                 magic = (unsigned long) page->lru.next;
668
669                 BUG_ON(magic == NODE_INFO);
670
671                 maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
672                 removing_section_nr = page->private;
673
674                 /*
675                  * When this function is called, the removing section is
676                  * logical offlined state. This means all pages are isolated
677                  * from page allocator. If removing section's memmap is placed
678                  * on the same section, it must not be freed.
679                  * If it is freed, page allocator may allocate it which will
680                  * be removed physically soon.
681                  */
682                 if (maps_section_nr != removing_section_nr)
683                         put_page_bootmem(page);
684         }
685 }
686 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
687
688 static void free_section_usemap(struct page *memmap, unsigned long *usemap)
689 {
690         struct page *usemap_page;
691         unsigned long nr_pages;
692
693         if (!usemap)
694                 return;
695
696         usemap_page = virt_to_page(usemap);
697         /*
698          * Check to see if allocation came from hot-plug-add
699          */
700         if (PageSlab(usemap_page)) {
701                 kfree(usemap);
702                 if (memmap)
703                         __kfree_section_memmap(memmap, PAGES_PER_SECTION);
704                 return;
705         }
706
707         /*
708          * The usemap came from bootmem. This is packed with other usemaps
709          * on the section which has pgdat at boot time. Just keep it as is now.
710          */
711
712         if (memmap) {
713                 struct page *memmap_page;
714                 memmap_page = virt_to_page(memmap);
715
716                 nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
717                         >> PAGE_SHIFT;
718
719                 free_map_bootmem(memmap_page, nr_pages);
720         }
721 }
722
723 /*
724  * returns the number of sections whose mem_maps were properly
725  * set.  If this is <=0, then that means that the passed-in
726  * map was not consumed and must be freed.
727  */
728 int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
729                            int nr_pages)
730 {
731         unsigned long section_nr = pfn_to_section_nr(start_pfn);
732         struct pglist_data *pgdat = zone->zone_pgdat;
733         struct mem_section *ms;
734         struct page *memmap;
735         unsigned long *usemap;
736         unsigned long flags;
737         int ret;
738
739         /*
740          * no locking for this, because it does its own
741          * plus, it does a kmalloc
742          */
743         ret = sparse_index_init(section_nr, pgdat->node_id);
744         if (ret < 0 && ret != -EEXIST)
745                 return ret;
746         memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, nr_pages);
747         if (!memmap)
748                 return -ENOMEM;
749         usemap = __kmalloc_section_usemap();
750         if (!usemap) {
751                 __kfree_section_memmap(memmap, nr_pages);
752                 return -ENOMEM;
753         }
754
755         pgdat_resize_lock(pgdat, &flags);
756
757         ms = __pfn_to_section(start_pfn);
758         if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
759                 ret = -EEXIST;
760                 goto out;
761         }
762
763         ms->section_mem_map |= SECTION_MARKED_PRESENT;
764
765         ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
766
767 out:
768         pgdat_resize_unlock(pgdat, &flags);
769         if (ret <= 0) {
770                 kfree(usemap);
771                 __kfree_section_memmap(memmap, nr_pages);
772         }
773         return ret;
774 }
775
776 void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
777 {
778         struct page *memmap = NULL;
779         unsigned long *usemap = NULL;
780
781         if (ms->section_mem_map) {
782                 usemap = ms->pageblock_flags;
783                 memmap = sparse_decode_mem_map(ms->section_mem_map,
784                                                 __section_nr(ms));
785                 ms->section_mem_map = 0;
786                 ms->pageblock_flags = NULL;
787         }
788
789         free_section_usemap(memmap, usemap);
790 }
791 #endif