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, bool skip_hwpoisoned_pages) 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 skip_hwpoisoned_pages)) 71 ret = 0; 72 73 /* 74 * immobile means "not-on-lru" paes. If immobile is larger than 75 * removable-by-driver pages reported by notifier, we'll fail. 76 */ 77 78 out: 79 if (!ret) { 80 unsigned long nr_pages; 81 int migratetype = get_pageblock_migratetype(page); 82 83 set_pageblock_isolate(page); 84 nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE); 85 86 __mod_zone_freepage_state(zone, -nr_pages, migratetype); 87 } 88 89 spin_unlock_irqrestore(&zone->lock, flags); 90 if (!ret) 91 drain_all_pages(); 92 return ret; 93 } 94 95 void unset_migratetype_isolate(struct page *page, unsigned migratetype) 96 { 97 struct zone *zone; 98 unsigned long flags, nr_pages; 99 100 zone = page_zone(page); 101 spin_lock_irqsave(&zone->lock, flags); 102 if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE) 103 goto out; 104 nr_pages = move_freepages_block(zone, page, migratetype); 105 __mod_zone_freepage_state(zone, nr_pages, migratetype); 106 restore_pageblock_isolate(page, migratetype); 107 out: 108 spin_unlock_irqrestore(&zone->lock, flags); 109 } 110 111 static inline struct page * 112 __first_valid_page(unsigned long pfn, unsigned long nr_pages) 113 { 114 int i; 115 for (i = 0; i < nr_pages; i++) 116 if (pfn_valid_within(pfn + i)) 117 break; 118 if (unlikely(i == nr_pages)) 119 return NULL; 120 return pfn_to_page(pfn + i); 121 } 122 123 /* 124 * start_isolate_page_range() -- make page-allocation-type of range of pages 125 * to be MIGRATE_ISOLATE. 126 * @start_pfn: The lower PFN of the range to be isolated. 127 * @end_pfn: The upper PFN of the range to be isolated. 128 * @migratetype: migrate type to set in error recovery. 129 * 130 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in 131 * the range will never be allocated. Any free pages and pages freed in the 132 * future will not be allocated again. 133 * 134 * start_pfn/end_pfn must be aligned to pageblock_order. 135 * Returns 0 on success and -EBUSY if any part of range cannot be isolated. 136 */ 137 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 138 unsigned migratetype, bool skip_hwpoisoned_pages) 139 { 140 unsigned long pfn; 141 unsigned long undo_pfn; 142 struct page *page; 143 144 BUG_ON((start_pfn) & (pageblock_nr_pages - 1)); 145 BUG_ON((end_pfn) & (pageblock_nr_pages - 1)); 146 147 for (pfn = start_pfn; 148 pfn < end_pfn; 149 pfn += pageblock_nr_pages) { 150 page = __first_valid_page(pfn, pageblock_nr_pages); 151 if (page && 152 set_migratetype_isolate(page, skip_hwpoisoned_pages)) { 153 undo_pfn = pfn; 154 goto undo; 155 } 156 } 157 return 0; 158 undo: 159 for (pfn = start_pfn; 160 pfn < undo_pfn; 161 pfn += pageblock_nr_pages) 162 unset_migratetype_isolate(pfn_to_page(pfn), migratetype); 163 164 return -EBUSY; 165 } 166 167 /* 168 * Make isolated pages available again. 169 */ 170 int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 171 unsigned migratetype) 172 { 173 unsigned long pfn; 174 struct page *page; 175 BUG_ON((start_pfn) & (pageblock_nr_pages - 1)); 176 BUG_ON((end_pfn) & (pageblock_nr_pages - 1)); 177 for (pfn = start_pfn; 178 pfn < end_pfn; 179 pfn += pageblock_nr_pages) { 180 page = __first_valid_page(pfn, pageblock_nr_pages); 181 if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE) 182 continue; 183 unset_migratetype_isolate(page, migratetype); 184 } 185 return 0; 186 } 187 /* 188 * Test all pages in the range is free(means isolated) or not. 189 * all pages in [start_pfn...end_pfn) must be in the same zone. 190 * zone->lock must be held before call this. 191 * 192 * Returns 1 if all pages in the range are isolated. 193 */ 194 static int 195 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, 196 bool skip_hwpoisoned_pages) 197 { 198 struct page *page; 199 200 while (pfn < end_pfn) { 201 if (!pfn_valid_within(pfn)) { 202 pfn++; 203 continue; 204 } 205 page = pfn_to_page(pfn); 206 if (PageBuddy(page)) { 207 /* 208 * If race between isolatation and allocation happens, 209 * some free pages could be in MIGRATE_MOVABLE list 210 * although pageblock's migratation type of the page 211 * is MIGRATE_ISOLATE. Catch it and move the page into 212 * MIGRATE_ISOLATE list. 213 */ 214 if (get_freepage_migratetype(page) != MIGRATE_ISOLATE) { 215 struct page *end_page; 216 217 end_page = page + (1 << page_order(page)) - 1; 218 move_freepages(page_zone(page), page, end_page, 219 MIGRATE_ISOLATE); 220 } 221 pfn += 1 << page_order(page); 222 } 223 else if (page_count(page) == 0 && 224 get_freepage_migratetype(page) == MIGRATE_ISOLATE) 225 pfn += 1; 226 else if (skip_hwpoisoned_pages && PageHWPoison(page)) { 227 /* 228 * The HWPoisoned page may be not in buddy 229 * system, and page_count() is not 0. 230 */ 231 pfn++; 232 continue; 233 } 234 else 235 break; 236 } 237 if (pfn < end_pfn) 238 return 0; 239 return 1; 240 } 241 242 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn, 243 bool skip_hwpoisoned_pages) 244 { 245 unsigned long pfn, flags; 246 struct page *page; 247 struct zone *zone; 248 int ret; 249 250 /* 251 * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page 252 * is not aligned to pageblock_nr_pages. 253 * Then we just check pagetype fist. 254 */ 255 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { 256 page = __first_valid_page(pfn, pageblock_nr_pages); 257 if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE) 258 break; 259 } 260 page = __first_valid_page(start_pfn, end_pfn - start_pfn); 261 if ((pfn < end_pfn) || !page) 262 return -EBUSY; 263 /* Check all pages are free or Marked as ISOLATED */ 264 zone = page_zone(page); 265 spin_lock_irqsave(&zone->lock, flags); 266 ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn, 267 skip_hwpoisoned_pages); 268 spin_unlock_irqrestore(&zone->lock, flags); 269 return ret ? 0 : -EBUSY; 270 } 271 272 struct page *alloc_migrate_target(struct page *page, unsigned long private, 273 int **resultp) 274 { 275 gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE; 276 277 if (PageHighMem(page)) 278 gfp_mask |= __GFP_HIGHMEM; 279 280 return alloc_page(gfp_mask); 281 } 282