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 } 236