mm/page_isolation.c

   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
  11 /* called while holding zone->lock */
  12 static void set_pageblock_isolate(struct page *page)
  13 {
  14         if (get_pageblock_migratetype(page) == MIGRATE_ISOLATE)
  15                 return;
  16
  17         set_pageblock_migratetype(page, MIGRATE_ISOLATE);
  18         page_zone(page)->nr_pageblock_isolate++;
  19 }
  20
  21 /* called while holding zone->lock */
  22 static void restore_pageblock_isolate(struct page *page, int migratetype)
  23 {
  24         struct zone *zone = page_zone(page);
  25         if (WARN_ON(get_pageblock_migratetype(page) != MIGRATE_ISOLATE))
  26                 return;
  27
  28         BUG_ON(zone->nr_pageblock_isolate <= 0);
  29         set_pageblock_migratetype(page, migratetype);
  30         zone->nr_pageblock_isolate--;
  31 }
  32
  33 int set_migratetype_isolate(struct page *page, bool skip_hwpoisoned_pages)
  34 {
  35         struct zone *zone;
  36         unsigned long flags, pfn;
  37         struct memory_isolate_notify arg;
  38         int notifier_ret;
  39         int ret = -EBUSY;
  40
  41         zone = page_zone(page);
  42
  43         spin_lock_irqsave(&zone->lock, flags);
  44
  45         pfn = page_to_pfn(page);
  46         arg.start_pfn = pfn;
  47         arg.nr_pages = pageblock_nr_pages;
  48         arg.pages_found = 0;
  49
  50         /*
  51          * It may be possible to isolate a pageblock even if the
  52          * migratetype is not MIGRATE_MOVABLE. The memory isolation
  53          * notifier chain is used by balloon drivers to return the
  54          * number of pages in a range that are held by the balloon
  55          * driver to shrink memory. If all the pages are accounted for
  56          * by balloons, are free, or on the LRU, isolation can continue.
  57          * Later, for example, when memory hotplug notifier runs, these
  58          * pages reported as "can be isolated" should be isolated(freed)
  59          * by the balloon driver through the memory notifier chain.
  60          */
  61         notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
  62         notifier_ret = notifier_to_errno(notifier_ret);
  63         if (notifier_ret)
  64                 goto out;
  65         /*
  66          * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
  67          * We just check MOVABLE pages.
  68          */
  69         if (!has_unmovable_pages(zone, page, arg.pages_found,
  70                                  skip_hwpoisoned_pages))
  71                 ret = 0;
  72
  73         /*
  74          * immobile means "not-on-lru" paes. If immobile is larger than
  75          * removable-by-driver pages reported by notifier, we'll fail.
  76          */
  77
  78 out:
  79         if (!ret) {
  80                 unsigned long nr_pages;
  81                 int migratetype = get_pageblock_migratetype(page);
  82
  83                 set_pageblock_isolate(page);
  84                 nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
  85
  86                 __mod_zone_freepage_state(zone, -nr_pages, migratetype);
  87         }
  88
  89         spin_unlock_irqrestore(&zone->lock, flags);
  90         if (!ret)
  91                 drain_all_pages();
  92         return ret;
  93 }
  94
  95 void unset_migratetype_isolate(struct page *page, unsigned migratetype)
  96 {
  97         struct zone *zone;
  98         unsigned long flags, nr_pages;
  99
 100         zone = page_zone(page);
 101         spin_lock_irqsave(&zone->lock, flags);
 102         if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 103                 goto out;
 104         nr_pages = move_freepages_block(zone, page, migratetype);
 105         __mod_zone_freepage_state(zone, nr_pages, migratetype);
 106         restore_pageblock_isolate(page, migratetype);
 107 out:
 108         spin_unlock_irqrestore(&zone->lock, flags);
 109 }
 110
 111 static inline struct page *
 112 __first_valid_page(unsigned long pfn, unsigned long nr_pages)
 113 {
 114         int i;
 115         for (i = 0; i < nr_pages; i++)
 116                 if (pfn_valid_within(pfn + i))
 117                         break;
 118         if (unlikely(i == nr_pages))
 119                 return NULL;
 120         return pfn_to_page(pfn + i);
 121 }
 122
 123 /*
 124  * start_isolate_page_range() -- make page-allocation-type of range of pages
 125  * to be MIGRATE_ISOLATE.
 126  * @start_pfn: The lower PFN of the range to be isolated.
 127  * @end_pfn: The upper PFN of the range to be isolated.
 128  * @migratetype: migrate type to set in error recovery.
 129  *
 130  * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
 131  * the range will never be allocated. Any free pages and pages freed in the
 132  * future will not be allocated again.
 133  *
 134  * start_pfn/end_pfn must be aligned to pageblock_order.
 135  * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
 136  */
 137 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 138                              unsigned migratetype, bool skip_hwpoisoned_pages)
 139 {
 140         unsigned long pfn;
 141         unsigned long undo_pfn;
 142         struct page *page;
 143
 144         BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
 145         BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
 146
 147         for (pfn = start_pfn;
 148              pfn < end_pfn;
 149              pfn += pageblock_nr_pages) {
 150                 page = __first_valid_page(pfn, pageblock_nr_pages);
 151                 if (page &&
 152                     set_migratetype_isolate(page, skip_hwpoisoned_pages)) {
 153                         undo_pfn = pfn;
 154                         goto undo;
 155                 }
 156         }
 157         return 0;
 158 undo:
 159         for (pfn = start_pfn;
 160              pfn < undo_pfn;
 161              pfn += pageblock_nr_pages)
 162                 unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
 163
 164         return -EBUSY;
 165 }
 166
 167 /*
 168  * Make isolated pages available again.
 169  */
 170 int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 171                             unsigned migratetype)
 172 {
 173         unsigned long pfn;
 174         struct page *page;
 175         BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
 176         BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
 177         for (pfn = start_pfn;
 178              pfn < end_pfn;
 179              pfn += pageblock_nr_pages) {
 180                 page = __first_valid_page(pfn, pageblock_nr_pages);
 181                 if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 182                         continue;
 183                 unset_migratetype_isolate(page, migratetype);
 184         }
 185         return 0;
 186 }
 187 /*
 188  * Test all pages in the range is free(means isolated) or not.
 189  * all pages in [start_pfn...end_pfn) must be in the same zone.
 190  * zone->lock must be held before call this.
 191  *
 192  * Returns 1 if all pages in the range are isolated.
 193  */
 194 static int
 195 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
 196                                   bool skip_hwpoisoned_pages)
 197 {
 198         struct page *page;
 199
 200         while (pfn < end_pfn) {
 201                 if (!pfn_valid_within(pfn)) {
 202                         pfn++;
 203                         continue;
 204                 }
 205                 page = pfn_to_page(pfn);
 206                 if (PageBuddy(page)) {
 207                         /*
 208                          * If race between isolatation and allocation happens,
 209                          * some free pages could be in MIGRATE_MOVABLE list
 210                          * although pageblock's migratation type of the page
 211                          * is MIGRATE_ISOLATE. Catch it and move the page into
 212                          * MIGRATE_ISOLATE list.
 213                          */
 214                         if (get_freepage_migratetype(page) != MIGRATE_ISOLATE) {
 215                                 struct page *end_page;
 216
 217                                 end_page = page + (1 << page_order(page)) - 1;
 218                                 move_freepages(page_zone(page), page, end_page,
 219                                                 MIGRATE_ISOLATE);
 220                         }
 221                         pfn += 1 << page_order(page);
 222                 }
 223                 else if (page_count(page) == 0 &&
 224                         get_freepage_migratetype(page) == MIGRATE_ISOLATE)
 225                         pfn += 1;
 226                 else if (skip_hwpoisoned_pages && PageHWPoison(page)) {
 227                         /*
 228                          * The HWPoisoned page may be not in buddy
 229                          * system, and page_count() is not 0.
 230                          */
 231                         pfn++;
 232                         continue;
 233                 }
 234                 else
 235                         break;
 236         }
 237         if (pfn < end_pfn)
 238                 return 0;
 239         return 1;
 240 }
 241
 242 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
 243                         bool skip_hwpoisoned_pages)
 244 {
 245         unsigned long pfn, flags;
 246         struct page *page;
 247         struct zone *zone;
 248         int ret;
 249
 250         /*
 251          * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page
 252          * is not aligned to pageblock_nr_pages.
 253          * Then we just check pagetype fist.
 254          */
 255         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 256                 page = __first_valid_page(pfn, pageblock_nr_pages);
 257                 if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 258                         break;
 259         }
 260         page = __first_valid_page(start_pfn, end_pfn - start_pfn);
 261         if ((pfn < end_pfn) || !page)
 262                 return -EBUSY;
 263         /* Check all pages are free or Marked as ISOLATED */
 264         zone = page_zone(page);
 265         spin_lock_irqsave(&zone->lock, flags);
 266         ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn,
 267                                                 skip_hwpoisoned_pages);
 268         spin_unlock_irqrestore(&zone->lock, flags);
 269         return ret ? 0 : -EBUSY;
 270 }
 271
 272 struct page *alloc_migrate_target(struct page *page, unsigned long private,
 273                                   int **resultp)
 274 {
 275         gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;
 276
 277         if (PageHighMem(page))
 278                 gfp_mask |= __GFP_HIGHMEM;
 279
 280         return alloc_page(gfp_mask);
 281 }