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/compiler.h>
9#include <linux/highmem.h>
10#include <linux/export.h>
11#include <linux/spinlock.h>
12#include <linux/vmalloc.h>
13
14#include "internal.h"
15#include <asm/dma.h>
16#include <asm/pgalloc.h>
17#include <asm/pgtable.h>
18
19/*
20 * Permanent SPARSEMEM data:
21 *
22 * 1) mem_section - memory sections, mem_map's for valid memory
23 */
24#ifdef CONFIG_SPARSEMEM_EXTREME
25struct mem_section *mem_section[NR_SECTION_ROOTS]
26    ____cacheline_internodealigned_in_smp;
27#else
28struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
29    ____cacheline_internodealigned_in_smp;
30#endif
31EXPORT_SYMBOL(mem_section);
32
33#ifdef NODE_NOT_IN_PAGE_FLAGS
34/*
35 * If we did not store the node number in the page then we have to
36 * do a lookup in the section_to_node_table in order to find which
37 * node the page belongs to.
38 */
39#if MAX_NUMNODES <= 256
40static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
41#else
42static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
43#endif
44
45int page_to_nid(const struct page *page)
46{
47    return section_to_node_table[page_to_section(page)];
48}
49EXPORT_SYMBOL(page_to_nid);
50
51static void set_section_nid(unsigned long section_nr, int nid)
52{
53    section_to_node_table[section_nr] = nid;
54}
55#else /* !NODE_NOT_IN_PAGE_FLAGS */
56static inline void set_section_nid(unsigned long section_nr, int nid)
57{
58}
59#endif
60
61#ifdef CONFIG_SPARSEMEM_EXTREME
62static struct mem_section noinline __init_refok *sparse_index_alloc(int nid)
63{
64    struct mem_section *section = NULL;
65    unsigned long array_size = SECTIONS_PER_ROOT *
66                   sizeof(struct mem_section);
67
68    if (slab_is_available()) {
69        if (node_state(nid, N_HIGH_MEMORY))
70            section = kzalloc_node(array_size, GFP_KERNEL, nid);
71        else
72            section = kzalloc(array_size, GFP_KERNEL);
73    } else {
74        section = memblock_virt_alloc_node(array_size, nid);
75    }
76
77    return section;
78}
79
80static int __meminit sparse_index_init(unsigned long section_nr, int nid)
81{
82    unsigned long root = SECTION_NR_TO_ROOT(section_nr);
83    struct mem_section *section;
84
85    if (mem_section[root])
86        return -EEXIST;
87
88    section = sparse_index_alloc(nid);
89    if (!section)
90        return -ENOMEM;
91
92    mem_section[root] = section;
93
94    return 0;
95}
96#else /* !SPARSEMEM_EXTREME */
97static inline int sparse_index_init(unsigned long section_nr, int nid)
98{
99    return 0;
100}
101#endif
102
103/*
104 * Although written for the SPARSEMEM_EXTREME case, this happens
105 * to also work for the flat array case because
106 * NR_SECTION_ROOTS==NR_MEM_SECTIONS.
107 */
108int __section_nr(struct mem_section* ms)
109{
110    unsigned long root_nr;
111    struct mem_section* root;
112
113    for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
114        root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
115        if (!root)
116            continue;
117
118        if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
119             break;
120    }
121
122    VM_BUG_ON(root_nr == NR_SECTION_ROOTS);
123
124    return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
125}
126
127/*
128 * During early boot, before section_mem_map is used for an actual
129 * mem_map, we use section_mem_map to store the section's NUMA
130 * node. This keeps us from having to use another data structure. The
131 * node information is cleared just before we store the real mem_map.
132 */
133static inline unsigned long sparse_encode_early_nid(int nid)
134{
135    return (nid << SECTION_NID_SHIFT);
136}
137
138static inline int sparse_early_nid(struct mem_section *section)
139{
140    return (section->section_mem_map >> SECTION_NID_SHIFT);
141}
142
143/* Validate the physical addressing limitations of the model */
144void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
145                        unsigned long *end_pfn)
146{
147    unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
148
149    /*
150     * Sanity checks - do not allow an architecture to pass
151     * in larger pfns than the maximum scope of sparsemem:
152     */
153    if (*start_pfn > max_sparsemem_pfn) {
154        mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
155            "Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
156            *start_pfn, *end_pfn, max_sparsemem_pfn);
157        WARN_ON_ONCE(1);
158        *start_pfn = max_sparsemem_pfn;
159        *end_pfn = max_sparsemem_pfn;
160    } else if (*end_pfn > max_sparsemem_pfn) {
161        mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
162            "End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
163            *start_pfn, *end_pfn, max_sparsemem_pfn);
164        WARN_ON_ONCE(1);
165        *end_pfn = max_sparsemem_pfn;
166    }
167}
168
169/* Record a memory area against a node. */
170void __init memory_present(int nid, unsigned long start, unsigned long end)
171{
172    unsigned long pfn;
173
174    start &= PAGE_SECTION_MASK;
175    mminit_validate_memmodel_limits(&start, &end);
176    for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
177        unsigned long section = pfn_to_section_nr(pfn);
178        struct mem_section *ms;
179
180        sparse_index_init(section, nid);
181        set_section_nid(section, nid);
182
183        ms = __nr_to_section(section);
184        if (!ms->section_mem_map)
185            ms->section_mem_map = sparse_encode_early_nid(nid) |
186                            SECTION_MARKED_PRESENT;
187    }
188}
189
190/*
191 * Only used by the i386 NUMA architecures, but relatively
192 * generic code.
193 */
194unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
195                             unsigned long end_pfn)
196{
197    unsigned long pfn;
198    unsigned long nr_pages = 0;
199
200    mminit_validate_memmodel_limits(&start_pfn, &end_pfn);
201    for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
202        if (nid != early_pfn_to_nid(pfn))
203            continue;
204
205        if (pfn_present(pfn))
206            nr_pages += PAGES_PER_SECTION;
207    }
208
209    return nr_pages * sizeof(struct page);
210}
211
212/*
213 * Subtle, we encode the real pfn into the mem_map such that
214 * the identity pfn - section_mem_map will return the actual
215 * physical page frame number.
216 */
217static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
218{
219    return (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
220}
221
222/*
223 * Decode mem_map from the coded memmap
224 */
225struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
226{
227    /* mask off the extra low bits of information */
228    coded_mem_map &= SECTION_MAP_MASK;
229    return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
230}
231
232static int __meminit sparse_init_one_section(struct mem_section *ms,
233        unsigned long pnum, struct page *mem_map,
234        unsigned long *pageblock_bitmap)
235{
236    if (!present_section(ms))
237        return -EINVAL;
238
239    ms->section_mem_map &= ~SECTION_MAP_MASK;
240    ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
241                            SECTION_HAS_MEM_MAP;
242     ms->pageblock_flags = pageblock_bitmap;
243
244    return 1;
245}
246
247unsigned long usemap_size(void)
248{
249    unsigned long size_bytes;
250    size_bytes = roundup(SECTION_BLOCKFLAGS_BITS, 8) / 8;
251    size_bytes = roundup(size_bytes, sizeof(unsigned long));
252    return size_bytes;
253}
254
255#ifdef CONFIG_MEMORY_HOTPLUG
256static unsigned long *__kmalloc_section_usemap(void)
257{
258    return kmalloc(usemap_size(), GFP_KERNEL);
259}
260#endif /* CONFIG_MEMORY_HOTPLUG */
261
262#ifdef CONFIG_MEMORY_HOTREMOVE
263static unsigned long * __init
264sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
265                     unsigned long size)
266{
267    unsigned long goal, limit;
268    unsigned long *p;
269    int nid;
270    /*
271     * A page may contain usemaps for other sections preventing the
272     * page being freed and making a section unremovable while
273     * other sections referencing the usemap remain active. Similarly,
274     * a pgdat can prevent a section being removed. If section A
275     * contains a pgdat and section B contains the usemap, both
276     * sections become inter-dependent. This allocates usemaps
277     * from the same section as the pgdat where possible to avoid
278     * this problem.
279     */
280    goal = __pa(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
281    limit = goal + (1UL << PA_SECTION_SHIFT);
282    nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
283again:
284    p = memblock_virt_alloc_try_nid_nopanic(size,
285                        SMP_CACHE_BYTES, goal, limit,
286                        nid);
287    if (!p && limit) {
288        limit = 0;
289        goto again;
290    }
291    return p;
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 size)
336{
337    return memblock_virt_alloc_node_nopanic(size, pgdat->node_id);
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(void *data,
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    unsigned long **usemap_map = (unsigned long **)data;
353    int size = usemap_size();
354
355    usemap = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nodeid),
356                              size * usemap_count);
357    if (!usemap) {
358        printk(KERN_WARNING "%s: allocation failed\n", __func__);
359        return;
360    }
361
362    for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
363        if (!present_section_nr(pnum))
364            continue;
365        usemap_map[pnum] = usemap;
366        usemap += size;
367        check_usemap_section_nr(nodeid, usemap_map[pnum]);
368    }
369}
370
371#ifndef CONFIG_SPARSEMEM_VMEMMAP
372struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid)
373{
374    struct page *map;
375    unsigned long size;
376
377    map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
378    if (map)
379        return map;
380
381    size = PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
382    map = memblock_virt_alloc_try_nid(size,
383                      PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
384                      BOOTMEM_ALLOC_ACCESSIBLE, nid);
385    return map;
386}
387void __init sparse_mem_maps_populate_node(struct page **map_map,
388                      unsigned long pnum_begin,
389                      unsigned long pnum_end,
390                      unsigned long map_count, int nodeid)
391{
392    void *map;
393    unsigned long pnum;
394    unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
395
396    map = alloc_remap(nodeid, size * map_count);
397    if (map) {
398        for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
399            if (!present_section_nr(pnum))
400                continue;
401            map_map[pnum] = map;
402            map += size;
403        }
404        return;
405    }
406
407    size = PAGE_ALIGN(size);
408    map = memblock_virt_alloc_try_nid(size * map_count,
409                      PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
410                      BOOTMEM_ALLOC_ACCESSIBLE, nodeid);
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(void *data,
440                 unsigned long pnum_begin,
441                 unsigned long pnum_end,
442                 unsigned long map_count, int nodeid)
443{
444    struct page **map_map = (struct page **)data;
445    sparse_mem_maps_populate_node(map_map, pnum_begin, pnum_end,
446                     map_count, nodeid);
447}
448#else
449static struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
450{
451    struct page *map;
452    struct mem_section *ms = __nr_to_section(pnum);
453    int nid = sparse_early_nid(ms);
454
455    map = sparse_mem_map_populate(pnum, nid);
456    if (map)
457        return map;
458
459    printk(KERN_ERR "%s: sparsemem memory map backing failed "
460            "some memory will not be available.\n", __func__);
461    ms->section_mem_map = 0;
462    return NULL;
463}
464#endif
465
466void __weak __meminit vmemmap_populate_print_last(void)
467{
468}
469
470/**
471 * alloc_usemap_and_memmap - memory alloction for pageblock flags and vmemmap
472 * @map: usemap_map for pageblock flags or mmap_map for vmemmap
473 */
474static void __init alloc_usemap_and_memmap(void (*alloc_func)
475                    (void *, unsigned long, unsigned long,
476                    unsigned long, int), void *data)
477{
478    unsigned long pnum;
479    unsigned long map_count;
480    int nodeid_begin = 0;
481    unsigned long pnum_begin = 0;
482
483    for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
484        struct mem_section *ms;
485
486        if (!present_section_nr(pnum))
487            continue;
488        ms = __nr_to_section(pnum);
489        nodeid_begin = sparse_early_nid(ms);
490        pnum_begin = pnum;
491        break;
492    }
493    map_count = 1;
494    for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
495        struct mem_section *ms;
496        int nodeid;
497
498        if (!present_section_nr(pnum))
499            continue;
500        ms = __nr_to_section(pnum);
501        nodeid = sparse_early_nid(ms);
502        if (nodeid == nodeid_begin) {
503            map_count++;
504            continue;
505        }
506        /* ok, we need to take cake of from pnum_begin to pnum - 1*/
507        alloc_func(data, pnum_begin, pnum,
508                        map_count, nodeid_begin);
509        /* new start, update count etc*/
510        nodeid_begin = nodeid;
511        pnum_begin = pnum;
512        map_count = 1;
513    }
514    /* ok, last chunk */
515    alloc_func(data, pnum_begin, NR_MEM_SECTIONS,
516                        map_count, nodeid_begin);
517}
518
519/*
520 * Allocate the accumulated non-linear sections, allocate a mem_map
521 * for each and record the physical to section mapping.
522 */
523void __init sparse_init(void)
524{
525    unsigned long pnum;
526    struct page *map;
527    unsigned long *usemap;
528    unsigned long **usemap_map;
529    int size;
530#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
531    int size2;
532    struct page **map_map;
533#endif
534
535    /* see include/linux/mmzone.h 'struct mem_section' definition */
536    BUILD_BUG_ON(!is_power_of_2(sizeof(struct mem_section)));
537
538    /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
539    set_pageblock_order();
540
541    /*
542     * map is using big page (aka 2M in x86 64 bit)
543     * usemap is less one page (aka 24 bytes)
544     * so alloc 2M (with 2M align) and 24 bytes in turn will
545     * make next 2M slip to one more 2M later.
546     * then in big system, the memory will have a lot of holes...
547     * here try to allocate 2M pages continuously.
548     *
549     * powerpc need to call sparse_init_one_section right after each
550     * sparse_early_mem_map_alloc, so allocate usemap_map at first.
551     */
552    size = sizeof(unsigned long *) * NR_MEM_SECTIONS;
553    usemap_map = memblock_virt_alloc(size, 0);
554    if (!usemap_map)
555        panic("can not allocate usemap_map\n");
556    alloc_usemap_and_memmap(sparse_early_usemaps_alloc_node,
557                            (void *)usemap_map);
558
559#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
560    size2 = sizeof(struct page *) * NR_MEM_SECTIONS;
561    map_map = memblock_virt_alloc(size2, 0);
562    if (!map_map)
563        panic("can not allocate map_map\n");
564    alloc_usemap_and_memmap(sparse_early_mem_maps_alloc_node,
565                            (void *)map_map);
566#endif
567
568    for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
569        if (!present_section_nr(pnum))
570            continue;
571
572        usemap = usemap_map[pnum];
573        if (!usemap)
574            continue;
575
576#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
577        map = map_map[pnum];
578#else
579        map = sparse_early_mem_map_alloc(pnum);
580#endif
581        if (!map)
582            continue;
583
584        sparse_init_one_section(__nr_to_section(pnum), pnum, map,
585                                usemap);
586    }
587
588    vmemmap_populate_print_last();
589
590#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
591    memblock_free_early(__pa(map_map), size2);
592#endif
593    memblock_free_early(__pa(usemap_map), size);
594}
595
596#ifdef CONFIG_MEMORY_HOTPLUG
597#ifdef CONFIG_SPARSEMEM_VMEMMAP
598static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid)
599{
600    /* This will make the necessary allocations eventually. */
601    return sparse_mem_map_populate(pnum, nid);
602}
603static void __kfree_section_memmap(struct page *memmap)
604{
605    unsigned long start = (unsigned long)memmap;
606    unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
607
608    vmemmap_free(start, end);
609}
610#ifdef CONFIG_MEMORY_HOTREMOVE
611static void free_map_bootmem(struct page *memmap)
612{
613    unsigned long start = (unsigned long)memmap;
614    unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
615
616    vmemmap_free(start, end);
617}
618#endif /* CONFIG_MEMORY_HOTREMOVE */
619#else
620static struct page *__kmalloc_section_memmap(void)
621{
622    struct page *page, *ret;
623    unsigned long memmap_size = sizeof(struct page) * PAGES_PER_SECTION;
624
625    page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
626    if (page)
627        goto got_map_page;
628
629    ret = vmalloc(memmap_size);
630    if (ret)
631        goto got_map_ptr;
632
633    return NULL;
634got_map_page:
635    ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
636got_map_ptr:
637
638    return ret;
639}
640
641static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid)
642{
643    return __kmalloc_section_memmap();
644}
645
646static void __kfree_section_memmap(struct page *memmap)
647{
648    if (is_vmalloc_addr(memmap))
649        vfree(memmap);
650    else
651        free_pages((unsigned long)memmap,
652               get_order(sizeof(struct page) * PAGES_PER_SECTION));
653}
654
655#ifdef CONFIG_MEMORY_HOTREMOVE
656static void free_map_bootmem(struct page *memmap)
657{
658    unsigned long maps_section_nr, removing_section_nr, i;
659    unsigned long magic, nr_pages;
660    struct page *page = virt_to_page(memmap);
661
662    nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
663        >> PAGE_SHIFT;
664
665    for (i = 0; i < nr_pages; i++, page++) {
666        magic = (unsigned long) page->lru.next;
667
668        BUG_ON(magic == NODE_INFO);
669
670        maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
671        removing_section_nr = page->private;
672
673        /*
674         * When this function is called, the removing section is
675         * logical offlined state. This means all pages are isolated
676         * from page allocator. If removing section's memmap is placed
677         * on the same section, it must not be freed.
678         * If it is freed, page allocator may allocate it which will
679         * be removed physically soon.
680         */
681        if (maps_section_nr != removing_section_nr)
682            put_page_bootmem(page);
683    }
684}
685#endif /* CONFIG_MEMORY_HOTREMOVE */
686#endif /* CONFIG_SPARSEMEM_VMEMMAP */
687
688/*
689 * returns the number of sections whose mem_maps were properly
690 * set. If this is <=0, then that means that the passed-in
691 * map was not consumed and must be freed.
692 */
693int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn)
694{
695    unsigned long section_nr = pfn_to_section_nr(start_pfn);
696    struct pglist_data *pgdat = zone->zone_pgdat;
697    struct mem_section *ms;
698    struct page *memmap;
699    unsigned long *usemap;
700    unsigned long flags;
701    int ret;
702
703    /*
704     * no locking for this, because it does its own
705     * plus, it does a kmalloc
706     */
707    ret = sparse_index_init(section_nr, pgdat->node_id);
708    if (ret < 0 && ret != -EEXIST)
709        return ret;
710    memmap = kmalloc_section_memmap(section_nr, pgdat->node_id);
711    if (!memmap)
712        return -ENOMEM;
713    usemap = __kmalloc_section_usemap();
714    if (!usemap) {
715        __kfree_section_memmap(memmap);
716        return -ENOMEM;
717    }
718
719    pgdat_resize_lock(pgdat, &flags);
720
721    ms = __pfn_to_section(start_pfn);
722    if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
723        ret = -EEXIST;
724        goto out;
725    }
726
727    memset(memmap, 0, sizeof(struct page) * PAGES_PER_SECTION);
728
729    ms->section_mem_map |= SECTION_MARKED_PRESENT;
730
731    ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
732
733out:
734    pgdat_resize_unlock(pgdat, &flags);
735    if (ret <= 0) {
736        kfree(usemap);
737        __kfree_section_memmap(memmap);
738    }
739    return ret;
740}
741
742#ifdef CONFIG_MEMORY_HOTREMOVE
743#ifdef CONFIG_MEMORY_FAILURE
744static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
745{
746    int i;
747
748    if (!memmap)
749        return;
750
751    for (i = 0; i < PAGES_PER_SECTION; i++) {
752        if (PageHWPoison(&memmap[i])) {
753            atomic_long_sub(1, &num_poisoned_pages);
754            ClearPageHWPoison(&memmap[i]);
755        }
756    }
757}
758#else
759static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
760{
761}
762#endif
763
764static void free_section_usemap(struct page *memmap, unsigned long *usemap)
765{
766    struct page *usemap_page;
767
768    if (!usemap)
769        return;
770
771    usemap_page = virt_to_page(usemap);
772    /*
773     * Check to see if allocation came from hot-plug-add
774     */
775    if (PageSlab(usemap_page) || PageCompound(usemap_page)) {
776        kfree(usemap);
777        if (memmap)
778            __kfree_section_memmap(memmap);
779        return;
780    }
781
782    /*
783     * The usemap came from bootmem. This is packed with other usemaps
784     * on the section which has pgdat at boot time. Just keep it as is now.
785     */
786
787    if (memmap)
788        free_map_bootmem(memmap);
789}
790
791void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
792{
793    struct page *memmap = NULL;
794    unsigned long *usemap = NULL, flags;
795    struct pglist_data *pgdat = zone->zone_pgdat;
796
797    pgdat_resize_lock(pgdat, &flags);
798    if (ms->section_mem_map) {
799        usemap = ms->pageblock_flags;
800        memmap = sparse_decode_mem_map(ms->section_mem_map,
801                        __section_nr(ms));
802        ms->section_mem_map = 0;
803        ms->pageblock_flags = NULL;
804    }
805    pgdat_resize_unlock(pgdat, &flags);
806
807    clear_hwpoisoned_pages(memmap, PAGES_PER_SECTION);
808    free_section_usemap(memmap, usemap);
809}
810#endif /* CONFIG_MEMORY_HOTREMOVE */
811#endif /* CONFIG_MEMORY_HOTPLUG */
812

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