Root/mm/memory_hotplug.c

1/*
2 * linux/mm/memory_hotplug.c
3 *
4 * Copyright (C)
5 */
6
7#include <linux/stddef.h>
8#include <linux/mm.h>
9#include <linux/swap.h>
10#include <linux/interrupt.h>
11#include <linux/pagemap.h>
12#include <linux/bootmem.h>
13#include <linux/compiler.h>
14#include <linux/module.h>
15#include <linux/pagevec.h>
16#include <linux/writeback.h>
17#include <linux/slab.h>
18#include <linux/sysctl.h>
19#include <linux/cpu.h>
20#include <linux/memory.h>
21#include <linux/memory_hotplug.h>
22#include <linux/highmem.h>
23#include <linux/vmalloc.h>
24#include <linux/ioport.h>
25#include <linux/delay.h>
26#include <linux/migrate.h>
27#include <linux/page-isolation.h>
28#include <linux/pfn.h>
29#include <linux/suspend.h>
30#include <linux/mm_inline.h>
31#include <linux/firmware-map.h>
32
33#include <asm/tlbflush.h>
34
35#include "internal.h"
36
37DEFINE_MUTEX(mem_hotplug_mutex);
38
39void lock_memory_hotplug(void)
40{
41    mutex_lock(&mem_hotplug_mutex);
42
43    /* for exclusive hibernation if CONFIG_HIBERNATION=y */
44    lock_system_sleep();
45}
46
47void unlock_memory_hotplug(void)
48{
49    unlock_system_sleep();
50    mutex_unlock(&mem_hotplug_mutex);
51}
52
53
54/* add this memory to iomem resource */
55static struct resource *register_memory_resource(u64 start, u64 size)
56{
57    struct resource *res;
58    res = kzalloc(sizeof(struct resource), GFP_KERNEL);
59    BUG_ON(!res);
60
61    res->name = "System RAM";
62    res->start = start;
63    res->end = start + size - 1;
64    res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
65    if (request_resource(&iomem_resource, res) < 0) {
66        printk("System RAM resource %llx - %llx cannot be added\n",
67        (unsigned long long)res->start, (unsigned long long)res->end);
68        kfree(res);
69        res = NULL;
70    }
71    return res;
72}
73
74static void release_memory_resource(struct resource *res)
75{
76    if (!res)
77        return;
78    release_resource(res);
79    kfree(res);
80    return;
81}
82
83#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
84#ifndef CONFIG_SPARSEMEM_VMEMMAP
85static void get_page_bootmem(unsigned long info, struct page *page,
86                 unsigned long type)
87{
88    page->lru.next = (struct list_head *) type;
89    SetPagePrivate(page);
90    set_page_private(page, info);
91    atomic_inc(&page->_count);
92}
93
94/* reference to __meminit __free_pages_bootmem is valid
95 * so use __ref to tell modpost not to generate a warning */
96void __ref put_page_bootmem(struct page *page)
97{
98    unsigned long type;
99
100    type = (unsigned long) page->lru.next;
101    BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
102           type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE);
103
104    if (atomic_dec_return(&page->_count) == 1) {
105        ClearPagePrivate(page);
106        set_page_private(page, 0);
107        INIT_LIST_HEAD(&page->lru);
108        __free_pages_bootmem(page, 0);
109    }
110
111}
112
113static void register_page_bootmem_info_section(unsigned long start_pfn)
114{
115    unsigned long *usemap, mapsize, section_nr, i;
116    struct mem_section *ms;
117    struct page *page, *memmap;
118
119    if (!pfn_valid(start_pfn))
120        return;
121
122    section_nr = pfn_to_section_nr(start_pfn);
123    ms = __nr_to_section(section_nr);
124
125    /* Get section's memmap address */
126    memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
127
128    /*
129     * Get page for the memmap's phys address
130     * XXX: need more consideration for sparse_vmemmap...
131     */
132    page = virt_to_page(memmap);
133    mapsize = sizeof(struct page) * PAGES_PER_SECTION;
134    mapsize = PAGE_ALIGN(mapsize) >> PAGE_SHIFT;
135
136    /* remember memmap's page */
137    for (i = 0; i < mapsize; i++, page++)
138        get_page_bootmem(section_nr, page, SECTION_INFO);
139
140    usemap = __nr_to_section(section_nr)->pageblock_flags;
141    page = virt_to_page(usemap);
142
143    mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT;
144
145    for (i = 0; i < mapsize; i++, page++)
146        get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
147
148}
149
150void register_page_bootmem_info_node(struct pglist_data *pgdat)
151{
152    unsigned long i, pfn, end_pfn, nr_pages;
153    int node = pgdat->node_id;
154    struct page *page;
155    struct zone *zone;
156
157    nr_pages = PAGE_ALIGN(sizeof(struct pglist_data)) >> PAGE_SHIFT;
158    page = virt_to_page(pgdat);
159
160    for (i = 0; i < nr_pages; i++, page++)
161        get_page_bootmem(node, page, NODE_INFO);
162
163    zone = &pgdat->node_zones[0];
164    for (; zone < pgdat->node_zones + MAX_NR_ZONES - 1; zone++) {
165        if (zone->wait_table) {
166            nr_pages = zone->wait_table_hash_nr_entries
167                * sizeof(wait_queue_head_t);
168            nr_pages = PAGE_ALIGN(nr_pages) >> PAGE_SHIFT;
169            page = virt_to_page(zone->wait_table);
170
171            for (i = 0; i < nr_pages; i++, page++)
172                get_page_bootmem(node, page, NODE_INFO);
173        }
174    }
175
176    pfn = pgdat->node_start_pfn;
177    end_pfn = pfn + pgdat->node_spanned_pages;
178
179    /* register_section info */
180    for (; pfn < end_pfn; pfn += PAGES_PER_SECTION)
181        register_page_bootmem_info_section(pfn);
182
183}
184#endif /* !CONFIG_SPARSEMEM_VMEMMAP */
185
186static void grow_zone_span(struct zone *zone, unsigned long start_pfn,
187               unsigned long end_pfn)
188{
189    unsigned long old_zone_end_pfn;
190
191    zone_span_writelock(zone);
192
193    old_zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
194    if (start_pfn < zone->zone_start_pfn)
195        zone->zone_start_pfn = start_pfn;
196
197    zone->spanned_pages = max(old_zone_end_pfn, end_pfn) -
198                zone->zone_start_pfn;
199
200    zone_span_writeunlock(zone);
201}
202
203static void grow_pgdat_span(struct pglist_data *pgdat, unsigned long start_pfn,
204                unsigned long end_pfn)
205{
206    unsigned long old_pgdat_end_pfn =
207        pgdat->node_start_pfn + pgdat->node_spanned_pages;
208
209    if (start_pfn < pgdat->node_start_pfn)
210        pgdat->node_start_pfn = start_pfn;
211
212    pgdat->node_spanned_pages = max(old_pgdat_end_pfn, end_pfn) -
213                    pgdat->node_start_pfn;
214}
215
216static int __meminit __add_zone(struct zone *zone, unsigned long phys_start_pfn)
217{
218    struct pglist_data *pgdat = zone->zone_pgdat;
219    int nr_pages = PAGES_PER_SECTION;
220    int nid = pgdat->node_id;
221    int zone_type;
222    unsigned long flags;
223
224    zone_type = zone - pgdat->node_zones;
225    if (!zone->wait_table) {
226        int ret;
227
228        ret = init_currently_empty_zone(zone, phys_start_pfn,
229                        nr_pages, MEMMAP_HOTPLUG);
230        if (ret)
231            return ret;
232    }
233    pgdat_resize_lock(zone->zone_pgdat, &flags);
234    grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages);
235    grow_pgdat_span(zone->zone_pgdat, phys_start_pfn,
236            phys_start_pfn + nr_pages);
237    pgdat_resize_unlock(zone->zone_pgdat, &flags);
238    memmap_init_zone(nr_pages, nid, zone_type,
239             phys_start_pfn, MEMMAP_HOTPLUG);
240    return 0;
241}
242
243static int __meminit __add_section(int nid, struct zone *zone,
244                    unsigned long phys_start_pfn)
245{
246    int nr_pages = PAGES_PER_SECTION;
247    int ret;
248
249    if (pfn_valid(phys_start_pfn))
250        return -EEXIST;
251
252    ret = sparse_add_one_section(zone, phys_start_pfn, nr_pages);
253
254    if (ret < 0)
255        return ret;
256
257    ret = __add_zone(zone, phys_start_pfn);
258
259    if (ret < 0)
260        return ret;
261
262    return register_new_memory(nid, __pfn_to_section(phys_start_pfn));
263}
264
265#ifdef CONFIG_SPARSEMEM_VMEMMAP
266static int __remove_section(struct zone *zone, struct mem_section *ms)
267{
268    /*
269     * XXX: Freeing memmap with vmemmap is not implement yet.
270     * This should be removed later.
271     */
272    return -EBUSY;
273}
274#else
275static int __remove_section(struct zone *zone, struct mem_section *ms)
276{
277    unsigned long flags;
278    struct pglist_data *pgdat = zone->zone_pgdat;
279    int ret = -EINVAL;
280
281    if (!valid_section(ms))
282        return ret;
283
284    ret = unregister_memory_section(ms);
285    if (ret)
286        return ret;
287
288    pgdat_resize_lock(pgdat, &flags);
289    sparse_remove_one_section(zone, ms);
290    pgdat_resize_unlock(pgdat, &flags);
291    return 0;
292}
293#endif
294
295/*
296 * Reasonably generic function for adding memory. It is
297 * expected that archs that support memory hotplug will
298 * call this function after deciding the zone to which to
299 * add the new pages.
300 */
301int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn,
302            unsigned long nr_pages)
303{
304    unsigned long i;
305    int err = 0;
306    int start_sec, end_sec;
307    /* during initialize mem_map, align hot-added range to section */
308    start_sec = pfn_to_section_nr(phys_start_pfn);
309    end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
310
311    for (i = start_sec; i <= end_sec; i++) {
312        err = __add_section(nid, zone, i << PFN_SECTION_SHIFT);
313
314        /*
315         * EEXIST is finally dealt with by ioresource collision
316         * check. see add_memory() => register_memory_resource()
317         * Warning will be printed if there is collision.
318         */
319        if (err && (err != -EEXIST))
320            break;
321        err = 0;
322    }
323
324    return err;
325}
326EXPORT_SYMBOL_GPL(__add_pages);
327
328/**
329 * __remove_pages() - remove sections of pages from a zone
330 * @zone: zone from which pages need to be removed
331 * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
332 * @nr_pages: number of pages to remove (must be multiple of section size)
333 *
334 * Generic helper function to remove section mappings and sysfs entries
335 * for the section of the memory we are removing. Caller needs to make
336 * sure that pages are marked reserved and zones are adjust properly by
337 * calling offline_pages().
338 */
339int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
340         unsigned long nr_pages)
341{
342    unsigned long i, ret = 0;
343    int sections_to_remove;
344
345    /*
346     * We can only remove entire sections
347     */
348    BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
349    BUG_ON(nr_pages % PAGES_PER_SECTION);
350
351    sections_to_remove = nr_pages / PAGES_PER_SECTION;
352    for (i = 0; i < sections_to_remove; i++) {
353        unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
354        release_mem_region(pfn << PAGE_SHIFT,
355                   PAGES_PER_SECTION << PAGE_SHIFT);
356        ret = __remove_section(zone, __pfn_to_section(pfn));
357        if (ret)
358            break;
359    }
360    return ret;
361}
362EXPORT_SYMBOL_GPL(__remove_pages);
363
364void online_page(struct page *page)
365{
366    unsigned long pfn = page_to_pfn(page);
367
368    totalram_pages++;
369    if (pfn >= num_physpages)
370        num_physpages = pfn + 1;
371
372#ifdef CONFIG_HIGHMEM
373    if (PageHighMem(page))
374        totalhigh_pages++;
375#endif
376
377    ClearPageReserved(page);
378    init_page_count(page);
379    __free_page(page);
380}
381
382static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
383            void *arg)
384{
385    unsigned long i;
386    unsigned long onlined_pages = *(unsigned long *)arg;
387    struct page *page;
388    if (PageReserved(pfn_to_page(start_pfn)))
389        for (i = 0; i < nr_pages; i++) {
390            page = pfn_to_page(start_pfn + i);
391            online_page(page);
392            onlined_pages++;
393        }
394    *(unsigned long *)arg = onlined_pages;
395    return 0;
396}
397
398
399int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
400{
401    unsigned long onlined_pages = 0;
402    struct zone *zone;
403    int need_zonelists_rebuild = 0;
404    int nid;
405    int ret;
406    struct memory_notify arg;
407
408    lock_memory_hotplug();
409    arg.start_pfn = pfn;
410    arg.nr_pages = nr_pages;
411    arg.status_change_nid = -1;
412
413    nid = page_to_nid(pfn_to_page(pfn));
414    if (node_present_pages(nid) == 0)
415        arg.status_change_nid = nid;
416
417    ret = memory_notify(MEM_GOING_ONLINE, &arg);
418    ret = notifier_to_errno(ret);
419    if (ret) {
420        memory_notify(MEM_CANCEL_ONLINE, &arg);
421        unlock_memory_hotplug();
422        return ret;
423    }
424    /*
425     * This doesn't need a lock to do pfn_to_page().
426     * The section can't be removed here because of the
427     * memory_block->state_mutex.
428     */
429    zone = page_zone(pfn_to_page(pfn));
430    /*
431     * If this zone is not populated, then it is not in zonelist.
432     * This means the page allocator ignores this zone.
433     * So, zonelist must be updated after online.
434     */
435    mutex_lock(&zonelists_mutex);
436    if (!populated_zone(zone))
437        need_zonelists_rebuild = 1;
438
439    ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages,
440        online_pages_range);
441    if (ret) {
442        mutex_unlock(&zonelists_mutex);
443        printk(KERN_DEBUG "online_pages %lx at %lx failed\n",
444            nr_pages, pfn);
445        memory_notify(MEM_CANCEL_ONLINE, &arg);
446        unlock_memory_hotplug();
447        return ret;
448    }
449
450    zone->present_pages += onlined_pages;
451    zone->zone_pgdat->node_present_pages += onlined_pages;
452    if (need_zonelists_rebuild)
453        build_all_zonelists(zone);
454    else
455        zone_pcp_update(zone);
456
457    mutex_unlock(&zonelists_mutex);
458
459    init_per_zone_wmark_min();
460
461    if (onlined_pages) {
462        kswapd_run(zone_to_nid(zone));
463        node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
464    }
465
466    vm_total_pages = nr_free_pagecache_pages();
467
468    writeback_set_ratelimit();
469
470    if (onlined_pages)
471        memory_notify(MEM_ONLINE, &arg);
472    unlock_memory_hotplug();
473
474    return 0;
475}
476#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
477
478/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
479static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
480{
481    struct pglist_data *pgdat;
482    unsigned long zones_size[MAX_NR_ZONES] = {0};
483    unsigned long zholes_size[MAX_NR_ZONES] = {0};
484    unsigned long start_pfn = start >> PAGE_SHIFT;
485
486    pgdat = arch_alloc_nodedata(nid);
487    if (!pgdat)
488        return NULL;
489
490    arch_refresh_nodedata(nid, pgdat);
491
492    /* we can use NODE_DATA(nid) from here */
493
494    /* init node's zones as empty zones, we don't have any present pages.*/
495    free_area_init_node(nid, zones_size, start_pfn, zholes_size);
496
497    /*
498     * The node we allocated has no zone fallback lists. For avoiding
499     * to access not-initialized zonelist, build here.
500     */
501    mutex_lock(&zonelists_mutex);
502    build_all_zonelists(NULL);
503    mutex_unlock(&zonelists_mutex);
504
505    return pgdat;
506}
507
508static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
509{
510    arch_refresh_nodedata(nid, NULL);
511    arch_free_nodedata(pgdat);
512    return;
513}
514
515
516/*
517 * called by cpu_up() to online a node without onlined memory.
518 */
519int mem_online_node(int nid)
520{
521    pg_data_t *pgdat;
522    int ret;
523
524    lock_memory_hotplug();
525    pgdat = hotadd_new_pgdat(nid, 0);
526    if (!pgdat) {
527        ret = -ENOMEM;
528        goto out;
529    }
530    node_set_online(nid);
531    ret = register_one_node(nid);
532    BUG_ON(ret);
533
534out:
535    unlock_memory_hotplug();
536    return ret;
537}
538
539/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
540int __ref add_memory(int nid, u64 start, u64 size)
541{
542    pg_data_t *pgdat = NULL;
543    int new_pgdat = 0;
544    struct resource *res;
545    int ret;
546
547    lock_memory_hotplug();
548
549    res = register_memory_resource(start, size);
550    ret = -EEXIST;
551    if (!res)
552        goto out;
553
554    if (!node_online(nid)) {
555        pgdat = hotadd_new_pgdat(nid, start);
556        ret = -ENOMEM;
557        if (!pgdat)
558            goto out;
559        new_pgdat = 1;
560    }
561
562    /* call arch's memory hotadd */
563    ret = arch_add_memory(nid, start, size);
564
565    if (ret < 0)
566        goto error;
567
568    /* we online node here. we can't roll back from here. */
569    node_set_online(nid);
570
571    if (new_pgdat) {
572        ret = register_one_node(nid);
573        /*
574         * If sysfs file of new node can't create, cpu on the node
575         * can't be hot-added. There is no rollback way now.
576         * So, check by BUG_ON() to catch it reluctantly..
577         */
578        BUG_ON(ret);
579    }
580
581    /* create new memmap entry */
582    firmware_map_add_hotplug(start, start + size, "System RAM");
583
584    goto out;
585
586error:
587    /* rollback pgdat allocation and others */
588    if (new_pgdat)
589        rollback_node_hotadd(nid, pgdat);
590    if (res)
591        release_memory_resource(res);
592
593out:
594    unlock_memory_hotplug();
595    return ret;
596}
597EXPORT_SYMBOL_GPL(add_memory);
598
599#ifdef CONFIG_MEMORY_HOTREMOVE
600/*
601 * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
602 * set and the size of the free page is given by page_order(). Using this,
603 * the function determines if the pageblock contains only free pages.
604 * Due to buddy contraints, a free page at least the size of a pageblock will
605 * be located at the start of the pageblock
606 */
607static inline int pageblock_free(struct page *page)
608{
609    return PageBuddy(page) && page_order(page) >= pageblock_order;
610}
611
612/* Return the start of the next active pageblock after a given page */
613static struct page *next_active_pageblock(struct page *page)
614{
615    /* Ensure the starting page is pageblock-aligned */
616    BUG_ON(page_to_pfn(page) & (pageblock_nr_pages - 1));
617
618    /* If the entire pageblock is free, move to the end of free page */
619    if (pageblock_free(page)) {
620        int order;
621        /* be careful. we don't have locks, page_order can be changed.*/
622        order = page_order(page);
623        if ((order < MAX_ORDER) && (order >= pageblock_order))
624            return page + (1 << order);
625    }
626
627    return page + pageblock_nr_pages;
628}
629
630/* Checks if this range of memory is likely to be hot-removable. */
631int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
632{
633    struct page *page = pfn_to_page(start_pfn);
634    struct page *end_page = page + nr_pages;
635
636    /* Check the starting page of each pageblock within the range */
637    for (; page < end_page; page = next_active_pageblock(page)) {
638        if (!is_pageblock_removable_nolock(page))
639            return 0;
640        cond_resched();
641    }
642
643    /* All pageblocks in the memory block are likely to be hot-removable */
644    return 1;
645}
646
647/*
648 * Confirm all pages in a range [start, end) is belongs to the same zone.
649 */
650static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
651{
652    unsigned long pfn;
653    struct zone *zone = NULL;
654    struct page *page;
655    int i;
656    for (pfn = start_pfn;
657         pfn < end_pfn;
658         pfn += MAX_ORDER_NR_PAGES) {
659        i = 0;
660        /* This is just a CONFIG_HOLES_IN_ZONE check.*/
661        while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i))
662            i++;
663        if (i == MAX_ORDER_NR_PAGES)
664            continue;
665        page = pfn_to_page(pfn + i);
666        if (zone && page_zone(page) != zone)
667            return 0;
668        zone = page_zone(page);
669    }
670    return 1;
671}
672
673/*
674 * Scanning pfn is much easier than scanning lru list.
675 * Scan pfn from start to end and Find LRU page.
676 */
677static unsigned long scan_lru_pages(unsigned long start, unsigned long end)
678{
679    unsigned long pfn;
680    struct page *page;
681    for (pfn = start; pfn < end; pfn++) {
682        if (pfn_valid(pfn)) {
683            page = pfn_to_page(pfn);
684            if (PageLRU(page))
685                return pfn;
686        }
687    }
688    return 0;
689}
690
691static struct page *
692hotremove_migrate_alloc(struct page *page, unsigned long private, int **x)
693{
694    /* This should be improooooved!! */
695    return alloc_page(GFP_HIGHUSER_MOVABLE);
696}
697
698#define NR_OFFLINE_AT_ONCE_PAGES (256)
699static int
700do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
701{
702    unsigned long pfn;
703    struct page *page;
704    int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
705    int not_managed = 0;
706    int ret = 0;
707    LIST_HEAD(source);
708
709    for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
710        if (!pfn_valid(pfn))
711            continue;
712        page = pfn_to_page(pfn);
713        if (!get_page_unless_zero(page))
714            continue;
715        /*
716         * We can skip free pages. And we can only deal with pages on
717         * LRU.
718         */
719        ret = isolate_lru_page(page);
720        if (!ret) { /* Success */
721            put_page(page);
722            list_add_tail(&page->lru, &source);
723            move_pages--;
724            inc_zone_page_state(page, NR_ISOLATED_ANON +
725                        page_is_file_cache(page));
726
727        } else {
728#ifdef CONFIG_DEBUG_VM
729            printk(KERN_ALERT "removing pfn %lx from LRU failed\n",
730                   pfn);
731            dump_page(page);
732#endif
733            put_page(page);
734            /* Because we don't have big zone->lock. we should
735               check this again here. */
736            if (page_count(page)) {
737                not_managed++;
738                ret = -EBUSY;
739                break;
740            }
741        }
742    }
743    if (!list_empty(&source)) {
744        if (not_managed) {
745            putback_lru_pages(&source);
746            goto out;
747        }
748        /* this function returns # of failed pages */
749        ret = migrate_pages(&source, hotremove_migrate_alloc, 0,
750                                true, true);
751        if (ret)
752            putback_lru_pages(&source);
753    }
754out:
755    return ret;
756}
757
758/*
759 * remove from free_area[] and mark all as Reserved.
760 */
761static int
762offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
763            void *data)
764{
765    __offline_isolated_pages(start, start + nr_pages);
766    return 0;
767}
768
769static void
770offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
771{
772    walk_system_ram_range(start_pfn, end_pfn - start_pfn, NULL,
773                offline_isolated_pages_cb);
774}
775
776/*
777 * Check all pages in range, recoreded as memory resource, are isolated.
778 */
779static int
780check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
781            void *data)
782{
783    int ret;
784    long offlined = *(long *)data;
785    ret = test_pages_isolated(start_pfn, start_pfn + nr_pages);
786    offlined = nr_pages;
787    if (!ret)
788        *(long *)data += offlined;
789    return ret;
790}
791
792static long
793check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
794{
795    long offlined = 0;
796    int ret;
797
798    ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, &offlined,
799            check_pages_isolated_cb);
800    if (ret < 0)
801        offlined = (long)ret;
802    return offlined;
803}
804
805static int __ref offline_pages(unsigned long start_pfn,
806          unsigned long end_pfn, unsigned long timeout)
807{
808    unsigned long pfn, nr_pages, expire;
809    long offlined_pages;
810    int ret, drain, retry_max, node;
811    struct zone *zone;
812    struct memory_notify arg;
813
814    BUG_ON(start_pfn >= end_pfn);
815    /* at least, alignment against pageblock is necessary */
816    if (!IS_ALIGNED(start_pfn, pageblock_nr_pages))
817        return -EINVAL;
818    if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
819        return -EINVAL;
820    /* This makes hotplug much easier...and readable.
821       we assume this for now. .*/
822    if (!test_pages_in_a_zone(start_pfn, end_pfn))
823        return -EINVAL;
824
825    lock_memory_hotplug();
826
827    zone = page_zone(pfn_to_page(start_pfn));
828    node = zone_to_nid(zone);
829    nr_pages = end_pfn - start_pfn;
830
831    /* set above range as isolated */
832    ret = start_isolate_page_range(start_pfn, end_pfn);
833    if (ret)
834        goto out;
835
836    arg.start_pfn = start_pfn;
837    arg.nr_pages = nr_pages;
838    arg.status_change_nid = -1;
839    if (nr_pages >= node_present_pages(node))
840        arg.status_change_nid = node;
841
842    ret = memory_notify(MEM_GOING_OFFLINE, &arg);
843    ret = notifier_to_errno(ret);
844    if (ret)
845        goto failed_removal;
846
847    pfn = start_pfn;
848    expire = jiffies + timeout;
849    drain = 0;
850    retry_max = 5;
851repeat:
852    /* start memory hot removal */
853    ret = -EAGAIN;
854    if (time_after(jiffies, expire))
855        goto failed_removal;
856    ret = -EINTR;
857    if (signal_pending(current))
858        goto failed_removal;
859    ret = 0;
860    if (drain) {
861        lru_add_drain_all();
862        cond_resched();
863        drain_all_pages();
864    }
865
866    pfn = scan_lru_pages(start_pfn, end_pfn);
867    if (pfn) { /* We have page on LRU */
868        ret = do_migrate_range(pfn, end_pfn);
869        if (!ret) {
870            drain = 1;
871            goto repeat;
872        } else {
873            if (ret < 0)
874                if (--retry_max == 0)
875                    goto failed_removal;
876            yield();
877            drain = 1;
878            goto repeat;
879        }
880    }
881    /* drain all zone's lru pagevec, this is asyncronous... */
882    lru_add_drain_all();
883    yield();
884    /* drain pcp pages , this is synchrouns. */
885    drain_all_pages();
886    /* check again */
887    offlined_pages = check_pages_isolated(start_pfn, end_pfn);
888    if (offlined_pages < 0) {
889        ret = -EBUSY;
890        goto failed_removal;
891    }
892    printk(KERN_INFO "Offlined Pages %ld\n", offlined_pages);
893    /* Ok, all of our target is islaoted.
894       We cannot do rollback at this point. */
895    offline_isolated_pages(start_pfn, end_pfn);
896    /* reset pagetype flags and makes migrate type to be MOVABLE */
897    undo_isolate_page_range(start_pfn, end_pfn);
898    /* removal success */
899    zone->present_pages -= offlined_pages;
900    zone->zone_pgdat->node_present_pages -= offlined_pages;
901    totalram_pages -= offlined_pages;
902
903    init_per_zone_wmark_min();
904
905    if (!node_present_pages(node)) {
906        node_clear_state(node, N_HIGH_MEMORY);
907        kswapd_stop(node);
908    }
909
910    vm_total_pages = nr_free_pagecache_pages();
911    writeback_set_ratelimit();
912
913    memory_notify(MEM_OFFLINE, &arg);
914    unlock_memory_hotplug();
915    return 0;
916
917failed_removal:
918    printk(KERN_INFO "memory offlining %lx to %lx failed\n",
919        start_pfn, end_pfn);
920    memory_notify(MEM_CANCEL_OFFLINE, &arg);
921    /* pushback to free area */
922    undo_isolate_page_range(start_pfn, end_pfn);
923
924out:
925    unlock_memory_hotplug();
926    return ret;
927}
928
929int remove_memory(u64 start, u64 size)
930{
931    unsigned long start_pfn, end_pfn;
932
933    start_pfn = PFN_DOWN(start);
934    end_pfn = start_pfn + PFN_DOWN(size);
935    return offline_pages(start_pfn, end_pfn, 120 * HZ);
936}
937#else
938int remove_memory(u64 start, u64 size)
939{
940    return -EINVAL;
941}
942#endif /* CONFIG_MEMORY_HOTREMOVE */
943EXPORT_SYMBOL_GPL(remove_memory);
944

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