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 
   11 int 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 
   56 out:
   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 
   73 void 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);
   85 out:
   86         spin_unlock_irqrestore(&zone->lock, flags);
   87 }
   88 
   89 static 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  */
  115 int 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;
  136 undo:
  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  */
  148 int 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  */
  172 static 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 
  220 int 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 
  250 struct 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 }

Cache object: 7ad7a1862bc0fc06053393fe861c8963

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FreeBSD/Linux Kernel Cross Reference sys/mm/page_isolation.c

FreeBSD/Linux Kernel Cross Reference
sys/mm/page_isolation.c