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)
  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                 ret = 0;
  71
  72         /*
  73          * immobile means "not-on-lru" paes. If immobile is larger than
  74          * removable-by-driver pages reported by notifier, we'll fail.
  75          */
  76
  77 out:
  78         if (!ret) {
  79                 unsigned long nr_pages;
  80                 int migratetype = get_pageblock_migratetype(page);
  81
  82                 set_pageblock_isolate(page);
  83                 nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
  84
  85                 __mod_zone_freepage_state(zone, -nr_pages, migratetype);
  86         }
  87
  88         spin_unlock_irqrestore(&zone->lock, flags);
  89         if (!ret)
  90                 drain_all_pages();
  91         return ret;
  92 }
  93
  94 void unset_migratetype_isolate(struct page *page, unsigned migratetype)
  95 {
  96         struct zone *zone;
  97         unsigned long flags, nr_pages;
  98
  99         zone = page_zone(page);
 100         spin_lock_irqsave(&zone->lock, flags);
 101         if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 102                 goto out;
 103         nr_pages = move_freepages_block(zone, page, migratetype);
 104         __mod_zone_freepage_state(zone, nr_pages, migratetype);
 105         restore_pageblock_isolate(page, migratetype);
 106 out:
 107         spin_unlock_irqrestore(&zone->lock, flags);
 108 }
 109
 110 static inline struct page *
 111 __first_valid_page(unsigned long pfn, unsigned long nr_pages)
 112 {
 113         int i;
 114         for (i = 0; i < nr_pages; i++)
 115                 if (pfn_valid_within(pfn + i))
 116                         break;
 117         if (unlikely(i == nr_pages))
 118                 return NULL;
 119         return pfn_to_page(pfn + i);
 120 }
 121
 122 /*
 123  * start_isolate_page_range() -- make page-allocation-type of range of pages
 124  * to be MIGRATE_ISOLATE.
 125  * @start_pfn: The lower PFN of the range to be isolated.
 126  * @end_pfn: The upper PFN of the range to be isolated.
 127  * @migratetype: migrate type to set in error recovery.
 128  *
 129  * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
 130  * the range will never be allocated. Any free pages and pages freed in the
 131  * future will not be allocated again.
 132  *
 133  * start_pfn/end_pfn must be aligned to pageblock_order.
 134  * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
 135  */
 136 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 137                              unsigned migratetype)
 138 {
 139         unsigned long pfn;
 140         unsigned long undo_pfn;
 141         struct page *page;
 142
 143         BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
 144         BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
 145
 146         for (pfn = start_pfn;
 147              pfn < end_pfn;
 148              pfn += pageblock_nr_pages) {
 149                 page = __first_valid_page(pfn, pageblock_nr_pages);
 150                 if (page && set_migratetype_isolate(page)) {
 151                         undo_pfn = pfn;
 152                         goto undo;
 153                 }
 154         }
 155         return 0;
 156 undo:
 157         for (pfn = start_pfn;
 158              pfn < undo_pfn;
 159              pfn += pageblock_nr_pages)
 160                 unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
 161
 162         return -EBUSY;
 163 }
 164
 165 /*
 166  * Make isolated pages available again.
 167  */
 168 int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 169                             unsigned migratetype)
 170 {
 171         unsigned long pfn;
 172         struct page *page;
 173         BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
 174         BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
 175         for (pfn = start_pfn;
 176              pfn < end_pfn;
 177              pfn += pageblock_nr_pages) {
 178                 page = __first_valid_page(pfn, pageblock_nr_pages);
 179                 if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 180                         continue;
 181                 unset_migratetype_isolate(page, migratetype);
 182         }
 183         return 0;
 184 }
 185 /*
 186  * Test all pages in the range is free(means isolated) or not.
 187  * all pages in [start_pfn...end_pfn) must be in the same zone.
 188  * zone->lock must be held before call this.
 189  *
 190  * Returns 1 if all pages in the range are isolated.
 191  */
 192 static int
 193 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn)
 194 {
 195         struct page *page;
 196
 197         while (pfn < end_pfn) {
 198                 if (!pfn_valid_within(pfn)) {
 199                         pfn++;
 200                         continue;
 201                 }
 202                 page = pfn_to_page(pfn);
 203                 if (PageBuddy(page)) {
 204                         /*
 205                          * If race between isolatation and allocation happens,
 206                          * some free pages could be in MIGRATE_MOVABLE list
 207                          * although pageblock's migratation type of the page
 208                          * is MIGRATE_ISOLATE. Catch it and move the page into
 209                          * MIGRATE_ISOLATE list.
 210                          */
 211                         if (get_freepage_migratetype(page) != MIGRATE_ISOLATE) {
 212                                 struct page *end_page;
 213
 214                                 end_page = page + (1 << page_order(page)) - 1;
 215                                 move_freepages(page_zone(page), page, end_page,
 216                                                 MIGRATE_ISOLATE);
 217                         }
 218                         pfn += 1 << page_order(page);
 219                 }
 220                 else if (page_count(page) == 0 &&
 221                         get_freepage_migratetype(page) == MIGRATE_ISOLATE)
 222                         pfn += 1;
 223                 else
 224                         break;
 225         }
 226         if (pfn < end_pfn)
 227                 return 0;
 228         return 1;
 229 }
 230
 231 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 232 {
 233         unsigned long pfn, flags;
 234         struct page *page;
 235         struct zone *zone;
 236         int ret;
 237
 238         /*
 239          * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page
 240          * is not aligned to pageblock_nr_pages.
 241          * Then we just check pagetype fist.
 242          */
 243         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 244                 page = __first_valid_page(pfn, pageblock_nr_pages);
 245                 if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 246                         break;
 247         }
 248         page = __first_valid_page(start_pfn, end_pfn - start_pfn);
 249         if ((pfn < end_pfn) || !page)
 250                 return -EBUSY;
 251         /* Check all pages are free or Marked as ISOLATED */
 252         zone = page_zone(page);
 253         spin_lock_irqsave(&zone->lock, flags);
 254         ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn);
 255         spin_unlock_irqrestore(&zone->lock, flags);
 256         return ret ? 0 : -EBUSY;
 257 }
 258
 259 struct page *alloc_migrate_target(struct page *page, unsigned long private,
 260                                   int **resultp)
 261 {
 262         gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;
 263
 264         if (PageHighMem(page))
 265                 gfp_mask |= __GFP_HIGHMEM;
 266
 267         return alloc_page(gfp_mask);
 268 }