mm: memcg: only check for PageSwapCache when uncharging anon
[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 = 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 size)
277 {
278         unsigned long goal, limit;
279         unsigned long *p;
280         int nid;
281         /*
282          * A page may contain usemaps for other sections preventing the
283          * page being freed and making a section unremovable while
284          * other sections referencing the usemap retmain active. Similarly,
285          * a pgdat can prevent a section being removed. If section A
286          * contains a pgdat and section B contains the usemap, both
287          * sections become inter-dependent. This allocates usemaps
288          * from the same section as the pgdat where possible to avoid
289          * this problem.
290          */
291         goal = __pa(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
292         limit = goal + (1UL << PA_SECTION_SHIFT);
293         nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
294 again:
295         p = ___alloc_bootmem_node_nopanic(NODE_DATA(nid), size,
296                                           SMP_CACHE_BYTES, goal, limit);
297         if (!p && limit) {
298                 limit = 0;
299                 goto again;
300         }
301         return p;
302 }
303
304 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
305 {
306         unsigned long usemap_snr, pgdat_snr;
307         static unsigned long old_usemap_snr = NR_MEM_SECTIONS;
308         static unsigned long old_pgdat_snr = NR_MEM_SECTIONS;
309         struct pglist_data *pgdat = NODE_DATA(nid);
310         int usemap_nid;
311
312         usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
313         pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
314         if (usemap_snr == pgdat_snr)
315                 return;
316
317         if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
318                 /* skip redundant message */
319                 return;
320
321         old_usemap_snr = usemap_snr;
322         old_pgdat_snr = pgdat_snr;
323
324         usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
325         if (usemap_nid != nid) {
326                 printk(KERN_INFO
327                        "node %d must be removed before remove section %ld\n",
328                        nid, usemap_snr);
329                 return;
330         }
331         /*
332          * There is a circular dependency.
333          * Some platforms allow un-removable section because they will just
334          * gather other removable sections for dynamic partitioning.
335          * Just notify un-removable section's number here.
336          */
337         printk(KERN_INFO "Section %ld and %ld (node %d)", usemap_snr,
338                pgdat_snr, nid);
339         printk(KERN_CONT
340                " have a circular dependency on usemap and pgdat allocations\n");
341 }
342 #else
343 static unsigned long * __init
344 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
345                                          unsigned long size)
346 {
347         return alloc_bootmem_node_nopanic(pgdat, size);
348 }
349
350 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
351 {
352 }
353 #endif /* CONFIG_MEMORY_HOTREMOVE */
354
355 static void __init sparse_early_usemaps_alloc_node(unsigned long**usemap_map,
356                                  unsigned long pnum_begin,
357                                  unsigned long pnum_end,
358                                  unsigned long usemap_count, int nodeid)
359 {
360         void *usemap;
361         unsigned long pnum;
362         int size = usemap_size();
363
364         usemap = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nodeid),
365                                                           size * usemap_count);
366         if (!usemap) {
367                 printk(KERN_WARNING "%s: allocation failed\n", __func__);
368                 return;
369         }
370
371         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
372                 if (!present_section_nr(pnum))
373                         continue;
374                 usemap_map[pnum] = usemap;
375                 usemap += size;
376                 check_usemap_section_nr(nodeid, usemap_map[pnum]);
377         }
378 }
379
380 #ifndef CONFIG_SPARSEMEM_VMEMMAP
381 struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid)
382 {
383         struct page *map;
384         unsigned long size;
385
386         map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
387         if (map)
388                 return map;
389
390         size = PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
391         map = __alloc_bootmem_node_high(NODE_DATA(nid), size,
392                                          PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
393         return map;
394 }
395 void __init sparse_mem_maps_populate_node(struct page **map_map,
396                                           unsigned long pnum_begin,
397                                           unsigned long pnum_end,
398                                           unsigned long map_count, int nodeid)
399 {
400         void *map;
401         unsigned long pnum;
402         unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
403
404         map = alloc_remap(nodeid, size * map_count);
405         if (map) {
406                 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
407                         if (!present_section_nr(pnum))
408                                 continue;
409                         map_map[pnum] = map;
410                         map += size;
411                 }
412                 return;
413         }
414
415         size = PAGE_ALIGN(size);
416         map = __alloc_bootmem_node_high(NODE_DATA(nodeid), size * map_count,
417                                          PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
418         if (map) {
419                 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
420                         if (!present_section_nr(pnum))
421                                 continue;
422                         map_map[pnum] = map;
423                         map += size;
424                 }
425                 return;
426         }
427
428         /* fallback */
429         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
430                 struct mem_section *ms;
431
432                 if (!present_section_nr(pnum))
433                         continue;
434                 map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
435                 if (map_map[pnum])
436                         continue;
437                 ms = __nr_to_section(pnum);
438                 printk(KERN_ERR "%s: sparsemem memory map backing failed "
439                         "some memory will not be available.\n", __func__);
440                 ms->section_mem_map = 0;
441         }
442 }
443 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
444
445 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
446 static void __init sparse_early_mem_maps_alloc_node(struct page **map_map,
447                                  unsigned long pnum_begin,
448                                  unsigned long pnum_end,
449                                  unsigned long map_count, int nodeid)
450 {
451         sparse_mem_maps_populate_node(map_map, pnum_begin, pnum_end,
452                                          map_count, nodeid);
453 }
454 #else
455 static struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
456 {
457         struct page *map;
458         struct mem_section *ms = __nr_to_section(pnum);
459         int nid = sparse_early_nid(ms);
460
461         map = sparse_mem_map_populate(pnum, nid);
462         if (map)
463                 return map;
464
465         printk(KERN_ERR "%s: sparsemem memory map backing failed "
466                         "some memory will not be available.\n", __func__);
467         ms->section_mem_map = 0;
468         return NULL;
469 }
470 #endif
471
472 void __attribute__((weak)) __meminit vmemmap_populate_print_last(void)
473 {
474 }
475
476 /*
477  * Allocate the accumulated non-linear sections, allocate a mem_map
478  * for each and record the physical to section mapping.
479  */
480 void __init sparse_init(void)
481 {
482         unsigned long pnum;
483         struct page *map;
484         unsigned long *usemap;
485         unsigned long **usemap_map;
486         int size;
487         int nodeid_begin = 0;
488         unsigned long pnum_begin = 0;
489         unsigned long usemap_count;
490 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
491         unsigned long map_count;
492         int size2;
493         struct page **map_map;
494 #endif
495
496         /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
497         set_pageblock_order();
498
499         /*
500          * map is using big page (aka 2M in x86 64 bit)
501          * usemap is less one page (aka 24 bytes)
502          * so alloc 2M (with 2M align) and 24 bytes in turn will
503          * make next 2M slip to one more 2M later.
504          * then in big system, the memory will have a lot of holes...
505          * here try to allocate 2M pages continuously.
506          *
507          * powerpc need to call sparse_init_one_section right after each
508          * sparse_early_mem_map_alloc, so allocate usemap_map at first.
509          */
510         size = sizeof(unsigned long *) * NR_MEM_SECTIONS;
511         usemap_map = alloc_bootmem(size);
512         if (!usemap_map)
513                 panic("can not allocate usemap_map\n");
514
515         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
516                 struct mem_section *ms;
517
518                 if (!present_section_nr(pnum))
519                         continue;
520                 ms = __nr_to_section(pnum);
521                 nodeid_begin = sparse_early_nid(ms);
522                 pnum_begin = pnum;
523                 break;
524         }
525         usemap_count = 1;
526         for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
527                 struct mem_section *ms;
528                 int nodeid;
529
530                 if (!present_section_nr(pnum))
531                         continue;
532                 ms = __nr_to_section(pnum);
533                 nodeid = sparse_early_nid(ms);
534                 if (nodeid == nodeid_begin) {
535                         usemap_count++;
536                         continue;
537                 }
538                 /* ok, we need to take cake of from pnum_begin to pnum - 1*/
539                 sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, pnum,
540                                                  usemap_count, nodeid_begin);
541                 /* new start, update count etc*/
542                 nodeid_begin = nodeid;
543                 pnum_begin = pnum;
544                 usemap_count = 1;
545         }
546         /* ok, last chunk */
547         sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, NR_MEM_SECTIONS,
548                                          usemap_count, nodeid_begin);
549
550 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
551         size2 = sizeof(struct page *) * NR_MEM_SECTIONS;
552         map_map = alloc_bootmem(size2);
553         if (!map_map)
554                 panic("can not allocate map_map\n");
555
556         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
557                 struct mem_section *ms;
558
559                 if (!present_section_nr(pnum))
560                         continue;
561                 ms = __nr_to_section(pnum);
562                 nodeid_begin = sparse_early_nid(ms);
563                 pnum_begin = pnum;
564                 break;
565         }
566         map_count = 1;
567         for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
568                 struct mem_section *ms;
569                 int nodeid;
570
571                 if (!present_section_nr(pnum))
572                         continue;
573                 ms = __nr_to_section(pnum);
574                 nodeid = sparse_early_nid(ms);
575                 if (nodeid == nodeid_begin) {
576                         map_count++;
577                         continue;
578                 }
579                 /* ok, we need to take cake of from pnum_begin to pnum - 1*/
580                 sparse_early_mem_maps_alloc_node(map_map, pnum_begin, pnum,
581                                                  map_count, nodeid_begin);
582                 /* new start, update count etc*/
583                 nodeid_begin = nodeid;
584                 pnum_begin = pnum;
585                 map_count = 1;
586         }
587         /* ok, last chunk */
588         sparse_early_mem_maps_alloc_node(map_map, pnum_begin, NR_MEM_SECTIONS,
589                                          map_count, nodeid_begin);
590 #endif
591
592         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
593                 if (!present_section_nr(pnum))
594                         continue;
595
596                 usemap = usemap_map[pnum];
597                 if (!usemap)
598                         continue;
599
600 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
601                 map = map_map[pnum];
602 #else
603                 map = sparse_early_mem_map_alloc(pnum);
604 #endif
605                 if (!map)
606                         continue;
607
608                 sparse_init_one_section(__nr_to_section(pnum), pnum, map,
609                                                                 usemap);
610         }
611
612         vmemmap_populate_print_last();
613
614 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
615         free_bootmem(__pa(map_map), size2);
616 #endif
617         free_bootmem(__pa(usemap_map), size);
618 }
619
620 #ifdef CONFIG_MEMORY_HOTPLUG
621 #ifdef CONFIG_SPARSEMEM_VMEMMAP
622 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
623                                                  unsigned long nr_pages)
624 {
625         /* This will make the necessary allocations eventually. */
626         return sparse_mem_map_populate(pnum, nid);
627 }
628 static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
629 {
630         return; /* XXX: Not implemented yet */
631 }
632 static void free_map_bootmem(struct page *page, unsigned long nr_pages)
633 {
634 }
635 #else
636 static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
637 {
638         struct page *page, *ret;
639         unsigned long memmap_size = sizeof(struct page) * nr_pages;
640
641         page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
642         if (page)
643                 goto got_map_page;
644
645         ret = vmalloc(memmap_size);
646         if (ret)
647                 goto got_map_ptr;
648
649         return NULL;
650 got_map_page:
651         ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
652 got_map_ptr:
653         memset(ret, 0, memmap_size);
654
655         return ret;
656 }
657
658 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
659                                                   unsigned long nr_pages)
660 {
661         return __kmalloc_section_memmap(nr_pages);
662 }
663
664 static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
665 {
666         if (is_vmalloc_addr(memmap))
667                 vfree(memmap);
668         else
669                 free_pages((unsigned long)memmap,
670                            get_order(sizeof(struct page) * nr_pages));
671 }
672
673 static void free_map_bootmem(struct page *page, unsigned long nr_pages)
674 {
675         unsigned long maps_section_nr, removing_section_nr, i;
676         unsigned long magic;
677
678         for (i = 0; i < nr_pages; i++, page++) {
679                 magic = (unsigned long) page->lru.next;
680
681                 BUG_ON(magic == NODE_INFO);
682
683                 maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
684                 removing_section_nr = page->private;
685
686                 /*
687                  * When this function is called, the removing section is
688                  * logical offlined state. This means all pages are isolated
689                  * from page allocator. If removing section's memmap is placed
690                  * on the same section, it must not be freed.
691                  * If it is freed, page allocator may allocate it which will
692                  * be removed physically soon.
693                  */
694                 if (maps_section_nr != removing_section_nr)
695                         put_page_bootmem(page);
696         }
697 }
698 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
699
700 static void free_section_usemap(struct page *memmap, unsigned long *usemap)
701 {
702         struct page *usemap_page;
703         unsigned long nr_pages;
704
705         if (!usemap)
706                 return;
707
708         usemap_page = virt_to_page(usemap);
709         /*
710          * Check to see if allocation came from hot-plug-add
711          */
712         if (PageSlab(usemap_page)) {
713                 kfree(usemap);
714                 if (memmap)
715                         __kfree_section_memmap(memmap, PAGES_PER_SECTION);
716                 return;
717         }
718
719         /*
720          * The usemap came from bootmem. This is packed with other usemaps
721          * on the section which has pgdat at boot time. Just keep it as is now.
722          */
723
724         if (memmap) {
725                 struct page *memmap_page;
726                 memmap_page = virt_to_page(memmap);
727
728                 nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
729                         >> PAGE_SHIFT;
730
731                 free_map_bootmem(memmap_page, nr_pages);
732         }
733 }
734
735 /*
736  * returns the number of sections whose mem_maps were properly
737  * set.  If this is <=0, then that means that the passed-in
738  * map was not consumed and must be freed.
739  */
740 int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
741                            int nr_pages)
742 {
743         unsigned long section_nr = pfn_to_section_nr(start_pfn);
744         struct pglist_data *pgdat = zone->zone_pgdat;
745         struct mem_section *ms;
746         struct page *memmap;
747         unsigned long *usemap;
748         unsigned long flags;
749         int ret;
750
751         /*
752          * no locking for this, because it does its own
753          * plus, it does a kmalloc
754          */
755         ret = sparse_index_init(section_nr, pgdat->node_id);
756         if (ret < 0 && ret != -EEXIST)
757                 return ret;
758         memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, nr_pages);
759         if (!memmap)
760                 return -ENOMEM;
761         usemap = __kmalloc_section_usemap();
762         if (!usemap) {
763                 __kfree_section_memmap(memmap, nr_pages);
764                 return -ENOMEM;
765         }
766
767         pgdat_resize_lock(pgdat, &flags);
768
769         ms = __pfn_to_section(start_pfn);
770         if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
771                 ret = -EEXIST;
772                 goto out;
773         }
774
775         ms->section_mem_map |= SECTION_MARKED_PRESENT;
776
777         ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
778
779 out:
780         pgdat_resize_unlock(pgdat, &flags);
781         if (ret <= 0) {
782                 kfree(usemap);
783                 __kfree_section_memmap(memmap, nr_pages);
784         }
785         return ret;
786 }
787
788 void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
789 {
790         struct page *memmap = NULL;
791         unsigned long *usemap = NULL;
792
793         if (ms->section_mem_map) {
794                 usemap = ms->pageblock_flags;
795                 memmap = sparse_decode_mem_map(ms->section_mem_map,
796                                                 __section_nr(ms));
797                 ms->section_mem_map = 0;
798                 ms->pageblock_flags = NULL;
799         }
800
801         free_section_usemap(memmap, usemap);
802 }
803 #endif