Root/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
23struct mem_section *mem_section[NR_SECTION_ROOTS]
24    ____cacheline_internodealigned_in_smp;
25#else
26struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
27    ____cacheline_internodealigned_in_smp;
28#endif
29EXPORT_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
38static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
39#else
40static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
41#endif
42
43int page_to_nid(const struct page *page)
44{
45    return section_to_node_table[page_to_section(page)];
46}
47EXPORT_SYMBOL(page_to_nid);
48
49static 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 */
54static inline void set_section_nid(unsigned long section_nr, int nid)
55{
56}
57#endif
58
59#ifdef CONFIG_SPARSEMEM_EXTREME
60static 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
80static 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;
105out:
106    spin_unlock(&index_init_lock);
107    return ret;
108}
109#else /* !SPARSEMEM_EXTREME */
110static 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 */
121int __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 */
144static inline unsigned long sparse_encode_early_nid(int nid)
145{
146    return (nid << SECTION_NID_SHIFT);
147}
148
149static 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 */
155void __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. */
181void __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 */
205unsigned 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 */
228static 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 */
236struct 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
243static 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
258unsigned 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
267static 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
274static unsigned long * __init
275sparse_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
294static 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
333static unsigned long * __init
334sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
335                     unsigned long count)
336{
337    return NULL;
338}
339
340static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
341{
342}
343#endif /* CONFIG_MEMORY_HOTREMOVE */
344
345static 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
374struct 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}
388void __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
439static 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
448static 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
465void __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 */
473void __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
612static 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}
618static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
619{
620    return; /* XXX: Not implemented yet */
621}
622static void free_map_bootmem(struct page *page, unsigned long nr_pages)
623{
624}
625#else
626static 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;
640got_map_page:
641    ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
642got_map_ptr:
643    memset(ret, 0, memmap_size);
644
645    return ret;
646}
647
648static 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
654static 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
663static 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
690static 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 */
730int __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
769out:
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
778void 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
794

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