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