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 = 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
78static 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 */
96static 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 */
107int __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 */
132static inline unsigned long sparse_encode_early_nid(int nid)
133{
134    return (nid << SECTION_NID_SHIFT);
135}
136
137static 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 */
143void __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. */
169void __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 */
193unsigned 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 */
216static 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 */
224struct 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
231static 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
246unsigned 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
255static 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
262static unsigned long * __init
263sparse_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);
282again:
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
292static 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
331static unsigned long * __init
332sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
333                     unsigned long size)
334{
335    return alloc_bootmem_node_nopanic(pgdat, size);
336}
337
338static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
339{
340}
341#endif /* CONFIG_MEMORY_HOTREMOVE */
342
343static 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
369struct 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}
383void __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
434static 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
443static 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
460void __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 */
468void __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
610static 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}
616static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
617{
618    return; /* XXX: Not implemented yet */
619}
620static void free_map_bootmem(struct page *page, unsigned long nr_pages)
621{
622}
623#else
624static 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;
638got_map_page:
639    ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
640got_map_ptr:
641    memset(ret, 0, memmap_size);
642
643    return ret;
644}
645
646static 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
652static 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
661static 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
688static 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 */
728int __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
767out:
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
776void 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
792

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