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/module.h>
10#include <linux/spinlock.h>
11#include <linux/vmalloc.h>
12#include "internal.h"
13#include <asm/dma.h>
14#include <asm/pgalloc.h>
15#include <asm/pgtable.h>
16
17/*
18 * Permanent SPARSEMEM data:
19 *
20 * 1) mem_section - memory sections, mem_map's for valid memory
21 */
22#ifdef CONFIG_SPARSEMEM_EXTREME
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(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        for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
358            if (!present_section_nr(pnum))
359                continue;
360            usemap_map[pnum] = usemap;
361            usemap += size;
362        }
363        return;
364    }
365
366    usemap = alloc_bootmem_node(NODE_DATA(nodeid), size * usemap_count);
367    if (usemap) {
368        for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
369            if (!present_section_nr(pnum))
370                continue;
371            usemap_map[pnum] = usemap;
372            usemap += size;
373            check_usemap_section_nr(nodeid, usemap_map[pnum]);
374        }
375        return;
376    }
377
378    printk(KERN_WARNING "%s: allocation failed\n", __func__);
379}
380
381#ifndef CONFIG_SPARSEMEM_VMEMMAP
382struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid)
383{
384    struct page *map;
385    unsigned long size;
386
387    map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
388    if (map)
389        return map;
390
391    size = PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
392    map = __alloc_bootmem_node_high(NODE_DATA(nid), size,
393                     PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
394    return map;
395}
396void __init sparse_mem_maps_populate_node(struct page **map_map,
397                      unsigned long pnum_begin,
398                      unsigned long pnum_end,
399                      unsigned long map_count, int nodeid)
400{
401    void *map;
402    unsigned long pnum;
403    unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
404
405    map = alloc_remap(nodeid, size * map_count);
406    if (map) {
407        for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
408            if (!present_section_nr(pnum))
409                continue;
410            map_map[pnum] = map;
411            map += size;
412        }
413        return;
414    }
415
416    size = PAGE_ALIGN(size);
417    map = __alloc_bootmem_node_high(NODE_DATA(nodeid), size * map_count,
418                     PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
419    if (map) {
420        for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
421            if (!present_section_nr(pnum))
422                continue;
423            map_map[pnum] = map;
424            map += size;
425        }
426        return;
427    }
428
429    /* fallback */
430    for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
431        struct mem_section *ms;
432
433        if (!present_section_nr(pnum))
434            continue;
435        map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
436        if (map_map[pnum])
437            continue;
438        ms = __nr_to_section(pnum);
439        printk(KERN_ERR "%s: sparsemem memory map backing failed "
440            "some memory will not be available.\n", __func__);
441        ms->section_mem_map = 0;
442    }
443}
444#endif /* !CONFIG_SPARSEMEM_VMEMMAP */
445
446#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
447static void __init sparse_early_mem_maps_alloc_node(struct page **map_map,
448                 unsigned long pnum_begin,
449                 unsigned long pnum_end,
450                 unsigned long map_count, int nodeid)
451{
452    sparse_mem_maps_populate_node(map_map, pnum_begin, pnum_end,
453                     map_count, nodeid);
454}
455#else
456static struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
457{
458    struct page *map;
459    struct mem_section *ms = __nr_to_section(pnum);
460    int nid = sparse_early_nid(ms);
461
462    map = sparse_mem_map_populate(pnum, nid);
463    if (map)
464        return map;
465
466    printk(KERN_ERR "%s: sparsemem memory map backing failed "
467            "some memory will not be available.\n", __func__);
468    ms->section_mem_map = 0;
469    return NULL;
470}
471#endif
472
473void __attribute__((weak)) __meminit vmemmap_populate_print_last(void)
474{
475}
476
477/*
478 * Allocate the accumulated non-linear sections, allocate a mem_map
479 * for each and record the physical to section mapping.
480 */
481void __init sparse_init(void)
482{
483    unsigned long pnum;
484    struct page *map;
485    unsigned long *usemap;
486    unsigned long **usemap_map;
487    int size;
488    int nodeid_begin = 0;
489    unsigned long pnum_begin = 0;
490    unsigned long usemap_count;
491#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
492    unsigned long map_count;
493    int size2;
494    struct page **map_map;
495#endif
496
497    /*
498     * map is using big page (aka 2M in x86 64 bit)
499     * usemap is less one page (aka 24 bytes)
500     * so alloc 2M (with 2M align) and 24 bytes in turn will
501     * make next 2M slip to one more 2M later.
502     * then in big system, the memory will have a lot of holes...
503     * here try to allocate 2M pages continuously.
504     *
505     * powerpc need to call sparse_init_one_section right after each
506     * sparse_early_mem_map_alloc, so allocate usemap_map at first.
507     */
508    size = sizeof(unsigned long *) * NR_MEM_SECTIONS;
509    usemap_map = alloc_bootmem(size);
510    if (!usemap_map)
511        panic("can not allocate usemap_map\n");
512
513    for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
514        struct mem_section *ms;
515
516        if (!present_section_nr(pnum))
517            continue;
518        ms = __nr_to_section(pnum);
519        nodeid_begin = sparse_early_nid(ms);
520        pnum_begin = pnum;
521        break;
522    }
523    usemap_count = 1;
524    for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
525        struct mem_section *ms;
526        int nodeid;
527
528        if (!present_section_nr(pnum))
529            continue;
530        ms = __nr_to_section(pnum);
531        nodeid = sparse_early_nid(ms);
532        if (nodeid == nodeid_begin) {
533            usemap_count++;
534            continue;
535        }
536        /* ok, we need to take cake of from pnum_begin to pnum - 1*/
537        sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, pnum,
538                         usemap_count, nodeid_begin);
539        /* new start, update count etc*/
540        nodeid_begin = nodeid;
541        pnum_begin = pnum;
542        usemap_count = 1;
543    }
544    /* ok, last chunk */
545    sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, NR_MEM_SECTIONS,
546                     usemap_count, nodeid_begin);
547
548#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
549    size2 = sizeof(struct page *) * NR_MEM_SECTIONS;
550    map_map = alloc_bootmem(size2);
551    if (!map_map)
552        panic("can not allocate map_map\n");
553
554    for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
555        struct mem_section *ms;
556
557        if (!present_section_nr(pnum))
558            continue;
559        ms = __nr_to_section(pnum);
560        nodeid_begin = sparse_early_nid(ms);
561        pnum_begin = pnum;
562        break;
563    }
564    map_count = 1;
565    for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
566        struct mem_section *ms;
567        int nodeid;
568
569        if (!present_section_nr(pnum))
570            continue;
571        ms = __nr_to_section(pnum);
572        nodeid = sparse_early_nid(ms);
573        if (nodeid == nodeid_begin) {
574            map_count++;
575            continue;
576        }
577        /* ok, we need to take cake of from pnum_begin to pnum - 1*/
578        sparse_early_mem_maps_alloc_node(map_map, pnum_begin, pnum,
579                         map_count, nodeid_begin);
580        /* new start, update count etc*/
581        nodeid_begin = nodeid;
582        pnum_begin = pnum;
583        map_count = 1;
584    }
585    /* ok, last chunk */
586    sparse_early_mem_maps_alloc_node(map_map, pnum_begin, NR_MEM_SECTIONS,
587                     map_count, nodeid_begin);
588#endif
589
590    for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
591        if (!present_section_nr(pnum))
592            continue;
593
594        usemap = usemap_map[pnum];
595        if (!usemap)
596            continue;
597
598#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
599        map = map_map[pnum];
600#else
601        map = sparse_early_mem_map_alloc(pnum);
602#endif
603        if (!map)
604            continue;
605
606        sparse_init_one_section(__nr_to_section(pnum), pnum, map,
607                                usemap);
608    }
609
610    vmemmap_populate_print_last();
611
612#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
613    free_bootmem(__pa(map_map), size2);
614#endif
615    free_bootmem(__pa(usemap_map), size);
616}
617
618#ifdef CONFIG_MEMORY_HOTPLUG
619#ifdef CONFIG_SPARSEMEM_VMEMMAP
620static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
621                         unsigned long nr_pages)
622{
623    /* This will make the necessary allocations eventually. */
624    return sparse_mem_map_populate(pnum, nid);
625}
626static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
627{
628    return; /* XXX: Not implemented yet */
629}
630static void free_map_bootmem(struct page *page, unsigned long nr_pages)
631{
632}
633#else
634static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
635{
636    struct page *page, *ret;
637    unsigned long memmap_size = sizeof(struct page) * nr_pages;
638
639    page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
640    if (page)
641        goto got_map_page;
642
643    ret = vmalloc(memmap_size);
644    if (ret)
645        goto got_map_ptr;
646
647    return NULL;
648got_map_page:
649    ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
650got_map_ptr:
651    memset(ret, 0, memmap_size);
652
653    return ret;
654}
655
656static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
657                          unsigned long nr_pages)
658{
659    return __kmalloc_section_memmap(nr_pages);
660}
661
662static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
663{
664    if (is_vmalloc_addr(memmap))
665        vfree(memmap);
666    else
667        free_pages((unsigned long)memmap,
668               get_order(sizeof(struct page) * nr_pages));
669}
670
671static void free_map_bootmem(struct page *page, unsigned long nr_pages)
672{
673    unsigned long maps_section_nr, removing_section_nr, i;
674    unsigned long magic;
675
676    for (i = 0; i < nr_pages; i++, page++) {
677        magic = (unsigned long) page->lru.next;
678
679        BUG_ON(magic == NODE_INFO);
680
681        maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
682        removing_section_nr = page->private;
683
684        /*
685         * When this function is called, the removing section is
686         * logical offlined state. This means all pages are isolated
687         * from page allocator. If removing section's memmap is placed
688         * on the same section, it must not be freed.
689         * If it is freed, page allocator may allocate it which will
690         * be removed physically soon.
691         */
692        if (maps_section_nr != removing_section_nr)
693            put_page_bootmem(page);
694    }
695}
696#endif /* CONFIG_SPARSEMEM_VMEMMAP */
697
698static void free_section_usemap(struct page *memmap, unsigned long *usemap)
699{
700    struct page *usemap_page;
701    unsigned long nr_pages;
702
703    if (!usemap)
704        return;
705
706    usemap_page = virt_to_page(usemap);
707    /*
708     * Check to see if allocation came from hot-plug-add
709     */
710    if (PageSlab(usemap_page)) {
711        kfree(usemap);
712        if (memmap)
713            __kfree_section_memmap(memmap, PAGES_PER_SECTION);
714        return;
715    }
716
717    /*
718     * The usemap came from bootmem. This is packed with other usemaps
719     * on the section which has pgdat at boot time. Just keep it as is now.
720     */
721
722    if (memmap) {
723        struct page *memmap_page;
724        memmap_page = virt_to_page(memmap);
725
726        nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
727            >> PAGE_SHIFT;
728
729        free_map_bootmem(memmap_page, nr_pages);
730    }
731}
732
733/*
734 * returns the number of sections whose mem_maps were properly
735 * set. If this is <=0, then that means that the passed-in
736 * map was not consumed and must be freed.
737 */
738int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
739               int nr_pages)
740{
741    unsigned long section_nr = pfn_to_section_nr(start_pfn);
742    struct pglist_data *pgdat = zone->zone_pgdat;
743    struct mem_section *ms;
744    struct page *memmap;
745    unsigned long *usemap;
746    unsigned long flags;
747    int ret;
748
749    /*
750     * no locking for this, because it does its own
751     * plus, it does a kmalloc
752     */
753    ret = sparse_index_init(section_nr, pgdat->node_id);
754    if (ret < 0 && ret != -EEXIST)
755        return ret;
756    memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, nr_pages);
757    if (!memmap)
758        return -ENOMEM;
759    usemap = __kmalloc_section_usemap();
760    if (!usemap) {
761        __kfree_section_memmap(memmap, nr_pages);
762        return -ENOMEM;
763    }
764
765    pgdat_resize_lock(pgdat, &flags);
766
767    ms = __pfn_to_section(start_pfn);
768    if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
769        ret = -EEXIST;
770        goto out;
771    }
772
773    ms->section_mem_map |= SECTION_MARKED_PRESENT;
774
775    ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
776
777out:
778    pgdat_resize_unlock(pgdat, &flags);
779    if (ret <= 0) {
780        kfree(usemap);
781        __kfree_section_memmap(memmap, nr_pages);
782    }
783    return ret;
784}
785
786void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
787{
788    struct page *memmap = NULL;
789    unsigned long *usemap = NULL;
790
791    if (ms->section_mem_map) {
792        usemap = ms->pageblock_flags;
793        memmap = sparse_decode_mem_map(ms->section_mem_map,
794                        __section_nr(ms));
795        ms->section_mem_map = 0;
796        ms->pageblock_flags = NULL;
797    }
798
799    free_section_usemap(memmap, usemap);
800}
801#endif
802

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