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 } 260