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 "internal.h" 9 10 static inline struct page * 11 __first_valid_page(unsigned long pfn, unsigned long nr_pages) 12 { 13 int i; 14 for (i = 0; i < nr_pages; i++) 15 if (pfn_valid_within(pfn + i)) 16 break; 17 if (unlikely(i == nr_pages)) 18 return NULL; 19 return pfn_to_page(pfn + i); 20 } 21 22 /* 23 * start_isolate_page_range() -- make page-allocation-type of range of pages 24 * to be MIGRATE_ISOLATE. 25 * @start_pfn: The lower PFN of the range to be isolated. 26 * @end_pfn: The upper PFN of the range to be isolated. 27 * 28 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in 29 * the range will never be allocated. Any free pages and pages freed in the 30 * future will not be allocated again. 31 * 32 * start_pfn/end_pfn must be aligned to pageblock_order. 33 * Returns 0 on success and -EBUSY if any part of range cannot be isolated. 34 */ 35 int 36 start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn) 37 { 38 unsigned long pfn; 39 unsigned long undo_pfn; 40 struct page *page; 41 42 BUG_ON((start_pfn) & (pageblock_nr_pages - 1)); 43 BUG_ON((end_pfn) & (pageblock_nr_pages - 1)); 44 45 for (pfn = start_pfn; 46 pfn < end_pfn; 47 pfn += pageblock_nr_pages) { 48 page = __first_valid_page(pfn, pageblock_nr_pages); 49 if (page && set_migratetype_isolate(page)) { 50 undo_pfn = pfn; 51 goto undo; 52 } 53 } 54 return 0; 55 undo: 56 for (pfn = start_pfn; 57 pfn < undo_pfn; 58 pfn += pageblock_nr_pages) 59 unset_migratetype_isolate(pfn_to_page(pfn)); 60 61 return -EBUSY; 62 } 63 64 /* 65 * Make isolated pages available again. 66 */ 67 int 68 undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn) 69 { 70 unsigned long pfn; 71 struct page *page; 72 BUG_ON((start_pfn) & (pageblock_nr_pages - 1)); 73 BUG_ON((end_pfn) & (pageblock_nr_pages - 1)); 74 for (pfn = start_pfn; 75 pfn < end_pfn; 76 pfn += pageblock_nr_pages) { 77 page = __first_valid_page(pfn, pageblock_nr_pages); 78 if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE) 79 continue; 80 unset_migratetype_isolate(page); 81 } 82 return 0; 83 } 84 /* 85 * Test all pages in the range is free(means isolated) or not. 86 * all pages in [start_pfn...end_pfn) must be in the same zone. 87 * zone->lock must be held before call this. 88 * 89 * Returns 1 if all pages in the range is isolated. 90 */ 91 static int 92 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn) 93 { 94 struct page *page; 95 96 while (pfn < end_pfn) { 97 if (!pfn_valid_within(pfn)) { 98 pfn++; 99 continue; 100 } 101 page = pfn_to_page(pfn); 102 if (PageBuddy(page)) 103 pfn += 1 << page_order(page); 104 else if (page_count(page) == 0 && 105 page_private(page) == MIGRATE_ISOLATE) 106 pfn += 1; 107 else 108 break; 109 } 110 if (pfn < end_pfn) 111 return 0; 112 return 1; 113 } 114 115 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn) 116 { 117 unsigned long pfn, flags; 118 struct page *page; 119 struct zone *zone; 120 int ret; 121 122 /* 123 * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page 124 * is not aligned to pageblock_nr_pages. 125 * Then we just check pagetype fist. 126 */ 127 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { 128 page = __first_valid_page(pfn, pageblock_nr_pages); 129 if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE) 130 break; 131 } 132 page = __first_valid_page(start_pfn, end_pfn - start_pfn); 133 if ((pfn < end_pfn) || !page) 134 return -EBUSY; 135 /* Check all pages are free or Marked as ISOLATED */ 136 zone = page_zone(page); 137 spin_lock_irqsave(&zone->lock, flags); 138 ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn); 139 spin_unlock_irqrestore(&zone->lock, flags); 140 return ret ? 0 : -EBUSY; 141 } 142