linux/mm/page_isolation.c
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   1/*
   2 * linux/mm/page_isolation.c
   3 */
   4
   5#include <linux/mm.h>
   6#include <linux/page-isolation.h>
   7#include <linux/pageblock-flags.h>
   8#include <linux/memory.h>
   9#include "internal.h"
  10
  11int set_migratetype_isolate(struct page *page, bool skip_hwpoisoned_pages)
  12{
  13        struct zone *zone;
  14        unsigned long flags, pfn;
  15        struct memory_isolate_notify arg;
  16        int notifier_ret;
  17        int ret = -EBUSY;
  18
  19        zone = page_zone(page);
  20
  21        spin_lock_irqsave(&zone->lock, flags);
  22
  23        pfn = page_to_pfn(page);
  24        arg.start_pfn = pfn;
  25        arg.nr_pages = pageblock_nr_pages;
  26        arg.pages_found = 0;
  27
  28        /*
  29         * It may be possible to isolate a pageblock even if the
  30         * migratetype is not MIGRATE_MOVABLE. The memory isolation
  31         * notifier chain is used by balloon drivers to return the
  32         * number of pages in a range that are held by the balloon
  33         * driver to shrink memory. If all the pages are accounted for
  34         * by balloons, are free, or on the LRU, isolation can continue.
  35         * Later, for example, when memory hotplug notifier runs, these
  36         * pages reported as "can be isolated" should be isolated(freed)
  37         * by the balloon driver through the memory notifier chain.
  38         */
  39        notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
  40        notifier_ret = notifier_to_errno(notifier_ret);
  41        if (notifier_ret)
  42                goto out;
  43        /*
  44         * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
  45         * We just check MOVABLE pages.
  46         */
  47        if (!has_unmovable_pages(zone, page, arg.pages_found,
  48                                 skip_hwpoisoned_pages))
  49                ret = 0;
  50
  51        /*
  52         * immobile means "not-on-lru" paes. If immobile is larger than
  53         * removable-by-driver pages reported by notifier, we'll fail.
  54         */
  55
  56out:
  57        if (!ret) {
  58                unsigned long nr_pages;
  59                int migratetype = get_pageblock_migratetype(page);
  60
  61                set_pageblock_migratetype(page, MIGRATE_ISOLATE);
  62                nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
  63
  64                __mod_zone_freepage_state(zone, -nr_pages, migratetype);
  65        }
  66
  67        spin_unlock_irqrestore(&zone->lock, flags);
  68        if (!ret)
  69                drain_all_pages();
  70        return ret;
  71}
  72
  73void unset_migratetype_isolate(struct page *page, unsigned migratetype)
  74{
  75        struct zone *zone;
  76        unsigned long flags, nr_pages;
  77
  78        zone = page_zone(page);
  79        spin_lock_irqsave(&zone->lock, flags);
  80        if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
  81                goto out;
  82        nr_pages = move_freepages_block(zone, page, migratetype);
  83        __mod_zone_freepage_state(zone, nr_pages, migratetype);
  84        set_pageblock_migratetype(page, migratetype);
  85out:
  86        spin_unlock_irqrestore(&zone->lock, flags);
  87}
  88
  89static inline struct page *
  90__first_valid_page(unsigned long pfn, unsigned long nr_pages)
  91{
  92        int i;
  93        for (i = 0; i < nr_pages; i++)
  94                if (pfn_valid_within(pfn + i))
  95                        break;
  96        if (unlikely(i == nr_pages))
  97                return NULL;
  98        return pfn_to_page(pfn + i);
  99}
 100
 101/*
 102 * start_isolate_page_range() -- make page-allocation-type of range of pages
 103 * to be MIGRATE_ISOLATE.
 104 * @start_pfn: The lower PFN of the range to be isolated.
 105 * @end_pfn: The upper PFN of the range to be isolated.
 106 * @migratetype: migrate type to set in error recovery.
 107 *
 108 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
 109 * the range will never be allocated. Any free pages and pages freed in the
 110 * future will not be allocated again.
 111 *
 112 * start_pfn/end_pfn must be aligned to pageblock_order.
 113 * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
 114 */
 115int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 116                             unsigned migratetype, bool skip_hwpoisoned_pages)
 117{
 118        unsigned long pfn;
 119        unsigned long undo_pfn;
 120        struct page *page;
 121
 122        BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
 123        BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
 124
 125        for (pfn = start_pfn;
 126             pfn < end_pfn;
 127             pfn += pageblock_nr_pages) {
 128                page = __first_valid_page(pfn, pageblock_nr_pages);
 129                if (page &&
 130                    set_migratetype_isolate(page, skip_hwpoisoned_pages)) {
 131                        undo_pfn = pfn;
 132                        goto undo;
 133                }
 134        }
 135        return 0;
 136undo:
 137        for (pfn = start_pfn;
 138             pfn < undo_pfn;
 139             pfn += pageblock_nr_pages)
 140                unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
 141
 142        return -EBUSY;
 143}
 144
 145/*
 146 * Make isolated pages available again.
 147 */
 148int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 149                            unsigned migratetype)
 150{
 151        unsigned long pfn;
 152        struct page *page;
 153        BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
 154        BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
 155        for (pfn = start_pfn;
 156             pfn < end_pfn;
 157             pfn += pageblock_nr_pages) {
 158                page = __first_valid_page(pfn, pageblock_nr_pages);
 159                if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 160                        continue;
 161                unset_migratetype_isolate(page, migratetype);
 162        }
 163        return 0;
 164}
 165/*
 166 * Test all pages in the range is free(means isolated) or not.
 167 * all pages in [start_pfn...end_pfn) must be in the same zone.
 168 * zone->lock must be held before call this.
 169 *
 170 * Returns 1 if all pages in the range are isolated.
 171 */
 172static int
 173__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
 174                                  bool skip_hwpoisoned_pages)
 175{
 176        struct page *page;
 177
 178        while (pfn < end_pfn) {
 179                if (!pfn_valid_within(pfn)) {
 180                        pfn++;
 181                        continue;
 182                }
 183                page = pfn_to_page(pfn);
 184                if (PageBuddy(page)) {
 185                        /*
 186                         * If race between isolatation and allocation happens,
 187                         * some free pages could be in MIGRATE_MOVABLE list
 188                         * although pageblock's migratation type of the page
 189                         * is MIGRATE_ISOLATE. Catch it and move the page into
 190                         * MIGRATE_ISOLATE list.
 191                         */
 192                        if (get_freepage_migratetype(page) != MIGRATE_ISOLATE) {
 193                                struct page *end_page;
 194
 195                                end_page = page + (1 << page_order(page)) - 1;
 196                                move_freepages(page_zone(page), page, end_page,
 197                                                MIGRATE_ISOLATE);
 198                        }
 199                        pfn += 1 << page_order(page);
 200                }
 201                else if (page_count(page) == 0 &&
 202                        get_freepage_migratetype(page) == MIGRATE_ISOLATE)
 203                        pfn += 1;
 204                else if (skip_hwpoisoned_pages && PageHWPoison(page)) {
 205                        /*
 206                         * The HWPoisoned page may be not in buddy
 207                         * system, and page_count() is not 0.
 208                         */
 209                        pfn++;
 210                        continue;
 211                }
 212                else
 213                        break;
 214        }
 215        if (pfn < end_pfn)
 216                return 0;
 217        return 1;
 218}
 219
 220int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
 221                        bool skip_hwpoisoned_pages)
 222{
 223        unsigned long pfn, flags;
 224        struct page *page;
 225        struct zone *zone;
 226        int ret;
 227
 228        /*
 229         * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page
 230         * is not aligned to pageblock_nr_pages.
 231         * Then we just check pagetype fist.
 232         */
 233        for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 234                page = __first_valid_page(pfn, pageblock_nr_pages);
 235                if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 236                        break;
 237        }
 238        page = __first_valid_page(start_pfn, end_pfn - start_pfn);
 239        if ((pfn < end_pfn) || !page)
 240                return -EBUSY;
 241        /* Check all pages are free or Marked as ISOLATED */
 242        zone = page_zone(page);
 243        spin_lock_irqsave(&zone->lock, flags);
 244        ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn,
 245                                                skip_hwpoisoned_pages);
 246        spin_unlock_irqrestore(&zone->lock, flags);
 247        return ret ? 0 : -EBUSY;
 248}
 249
 250struct page *alloc_migrate_target(struct page *page, unsigned long private,
 251                                  int **resultp)
 252{
 253        gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;
 254
 255        if (PageHighMem(page))
 256                gfp_mask |= __GFP_HIGHMEM;
 257
 258        return alloc_page(gfp_mask);
 259}
 260
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