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