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                 set_pageblock_isolate(page);
  80                 move_freepages_block(zone, page, MIGRATE_ISOLATE);
  81         }
  82
  83         spin_unlock_irqrestore(&zone->lock, flags);
  84         if (!ret)
  85                 drain_all_pages();
  86         return ret;
  87 }
  88
  89 void unset_migratetype_isolate(struct page *page, unsigned migratetype)
  90 {
  91         struct zone *zone;
  92         unsigned long flags;
  93         zone = page_zone(page);
  94         spin_lock_irqsave(&zone->lock, flags);
  95         if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
  96                 goto out;
  97         move_freepages_block(zone, page, migratetype);
  98         restore_pageblock_isolate(page, migratetype);
  99 out:
 100         spin_unlock_irqrestore(&zone->lock, flags);
 101 }
 102
 103 static inline struct page *
 104 __first_valid_page(unsigned long pfn, unsigned long nr_pages)
 105 {
 106         int i;
 107         for (i = 0; i < nr_pages; i++)
 108                 if (pfn_valid_within(pfn + i))
 109                         break;
 110         if (unlikely(i == nr_pages))
 111                 return NULL;
 112         return pfn_to_page(pfn + i);
 113 }
 114
 115 /*
 116  * start_isolate_page_range() -- make page-allocation-type of range of pages
 117  * to be MIGRATE_ISOLATE.
 118  * @start_pfn: The lower PFN of the range to be isolated.
 119  * @end_pfn: The upper PFN of the range to be isolated.
 120  * @migratetype: migrate type to set in error recovery.
 121  *
 122  * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
 123  * the range will never be allocated. Any free pages and pages freed in the
 124  * future will not be allocated again.
 125  *
 126  * start_pfn/end_pfn must be aligned to pageblock_order.
 127  * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
 128  */
 129 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 130                              unsigned migratetype)
 131 {
 132         unsigned long pfn;
 133         unsigned long undo_pfn;
 134         struct page *page;
 135
 136         BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
 137         BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
 138
 139         for (pfn = start_pfn;
 140              pfn < end_pfn;
 141              pfn += pageblock_nr_pages) {
 142                 page = __first_valid_page(pfn, pageblock_nr_pages);
 143                 if (page && set_migratetype_isolate(page)) {
 144                         undo_pfn = pfn;
 145                         goto undo;
 146                 }
 147         }
 148         return 0;
 149 undo:
 150         for (pfn = start_pfn;
 151              pfn < undo_pfn;
 152              pfn += pageblock_nr_pages)
 153                 unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
 154
 155         return -EBUSY;
 156 }
 157
 158 /*
 159  * Make isolated pages available again.
 160  */
 161 int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 162                             unsigned migratetype)
 163 {
 164         unsigned long pfn;
 165         struct page *page;
 166         BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
 167         BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
 168         for (pfn = start_pfn;
 169              pfn < end_pfn;
 170              pfn += pageblock_nr_pages) {
 171                 page = __first_valid_page(pfn, pageblock_nr_pages);
 172                 if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 173                         continue;
 174                 unset_migratetype_isolate(page, migratetype);
 175         }
 176         return 0;
 177 }
 178 /*
 179  * Test all pages in the range is free(means isolated) or not.
 180  * all pages in [start_pfn...end_pfn) must be in the same zone.
 181  * zone->lock must be held before call this.
 182  *
 183  * Returns 1 if all pages in the range are isolated.
 184  */
 185 static int
 186 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn)
 187 {
 188         struct page *page;
 189
 190         while (pfn < end_pfn) {
 191                 if (!pfn_valid_within(pfn)) {
 192                         pfn++;
 193                         continue;
 194                 }
 195                 page = pfn_to_page(pfn);
 196                 if (PageBuddy(page))
 197                         pfn += 1 << page_order(page);
 198                 else if (page_count(page) == 0 &&
 199                                 page_private(page) == MIGRATE_ISOLATE)
 200                         pfn += 1;
 201                 else
 202                         break;
 203         }
 204         if (pfn < end_pfn)
 205                 return 0;
 206         return 1;
 207 }
 208
 209 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 210 {
 211         unsigned long pfn, flags;
 212         struct page *page;
 213         struct zone *zone;
 214         int ret;
 215
 216         /*
 217          * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page
 218          * is not aligned to pageblock_nr_pages.
 219          * Then we just check pagetype fist.
 220          */
 221         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 222                 page = __first_valid_page(pfn, pageblock_nr_pages);
 223                 if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 224                         break;
 225         }
 226         page = __first_valid_page(start_pfn, end_pfn - start_pfn);
 227         if ((pfn < end_pfn) || !page)
 228                 return -EBUSY;
 229         /* Check all pages are free or Marked as ISOLATED */
 230         zone = page_zone(page);
 231         spin_lock_irqsave(&zone->lock, flags);
 232         ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn);
 233         spin_unlock_irqrestore(&zone->lock, flags);
 234         return ret ? 0 : -EBUSY;
 235 }