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 <linux/hugetlb.h> 10 #include "internal.h" 11 12 int set_migratetype_isolate(struct page *page, bool skip_hwpoisoned_pages) 13 { 14 struct zone *zone; 15 unsigned long flags, pfn; 16 struct memory_isolate_notify arg; 17 int notifier_ret; 18 int ret = -EBUSY; 19 20 zone = page_zone(page); 21 22 spin_lock_irqsave(&zone->lock, flags); 23 24 pfn = page_to_pfn(page); 25 arg.start_pfn = pfn; 26 arg.nr_pages = pageblock_nr_pages; 27 arg.pages_found = 0; 28 29 /* 30 * It may be possible to isolate a pageblock even if the 31 * migratetype is not MIGRATE_MOVABLE. The memory isolation 32 * notifier chain is used by balloon drivers to return the 33 * number of pages in a range that are held by the balloon 34 * driver to shrink memory. If all the pages are accounted for 35 * by balloons, are free, or on the LRU, isolation can continue. 36 * Later, for example, when memory hotplug notifier runs, these 37 * pages reported as "can be isolated" should be isolated(freed) 38 * by the balloon driver through the memory notifier chain. 39 */ 40 notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg); 41 notifier_ret = notifier_to_errno(notifier_ret); 42 if (notifier_ret) 43 goto out; 44 /* 45 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself. 46 * We just check MOVABLE pages. 47 */ 48 if (!has_unmovable_pages(zone, page, arg.pages_found, 49 skip_hwpoisoned_pages)) 50 ret = 0; 51 52 /* 53 * immobile means "not-on-lru" paes. If immobile is larger than 54 * removable-by-driver pages reported by notifier, we'll fail. 55 */ 56 57 out: 58 if (!ret) { 59 unsigned long nr_pages; 60 int migratetype = get_pageblock_migratetype(page); 61 62 set_pageblock_migratetype(page, MIGRATE_ISOLATE); 63 zone->nr_isolate_pageblock++; 64 nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE); 65 66 __mod_zone_freepage_state(zone, -nr_pages, migratetype); 67 } 68 69 spin_unlock_irqrestore(&zone->lock, flags); 70 if (!ret) 71 drain_all_pages(); 72 return ret; 73 } 74 75 void unset_migratetype_isolate(struct page *page, unsigned migratetype) 76 { 77 struct zone *zone; 78 unsigned long flags, nr_pages; 79 struct page *isolated_page = NULL; 80 unsigned int order; 81 unsigned long page_idx, buddy_idx; 82 struct page *buddy; 83 84 zone = page_zone(page); 85 spin_lock_irqsave(&zone->lock, flags); 86 if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE) 87 goto out; 88 89 /* 90 * Because freepage with more than pageblock_order on isolated 91 * pageblock is restricted to merge due to freepage counting problem, 92 * it is possible that there is free buddy page. 93 * move_freepages_block() doesn't care of merge so we need other 94 * approach in order to merge them. Isolation and free will make 95 * these pages to be merged. 96 */ 97 if (PageBuddy(page)) { 98 order = page_order(page); 99 if (order >= pageblock_order) { 100 page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1); 101 buddy_idx = __find_buddy_index(page_idx, order); 102 buddy = page + (buddy_idx - page_idx); 103 104 if (!is_migrate_isolate_page(buddy)) { 105 __isolate_free_page(page, order); 106 set_page_refcounted(page); 107 isolated_page = page; 108 } 109 } 110 } 111 112 /* 113 * If we isolate freepage with more than pageblock_order, there 114 * should be no freepage in the range, so we could avoid costly 115 * pageblock scanning for freepage moving. 116 */ 117 if (!isolated_page) { 118 nr_pages = move_freepages_block(zone, page, migratetype); 119 __mod_zone_freepage_state(zone, nr_pages, migratetype); 120 } 121 set_pageblock_migratetype(page, migratetype); 122 zone->nr_isolate_pageblock--; 123 out: 124 spin_unlock_irqrestore(&zone->lock, flags); 125 if (isolated_page) 126 __free_pages(isolated_page, order); 127 } 128 129 static inline struct page * 130 __first_valid_page(unsigned long pfn, unsigned long nr_pages) 131 { 132 int i; 133 for (i = 0; i < nr_pages; i++) 134 if (pfn_valid_within(pfn + i)) 135 break; 136 if (unlikely(i == nr_pages)) 137 return NULL; 138 return pfn_to_page(pfn + i); 139 } 140 141 /* 142 * start_isolate_page_range() -- make page-allocation-type of range of pages 143 * to be MIGRATE_ISOLATE. 144 * @start_pfn: The lower PFN of the range to be isolated. 145 * @end_pfn: The upper PFN of the range to be isolated. 146 * @migratetype: migrate type to set in error recovery. 147 * 148 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in 149 * the range will never be allocated. Any free pages and pages freed in the 150 * future will not be allocated again. 151 * 152 * start_pfn/end_pfn must be aligned to pageblock_order. 153 * Returns 0 on success and -EBUSY if any part of range cannot be isolated. 154 */ 155 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 156 unsigned migratetype, bool skip_hwpoisoned_pages) 157 { 158 unsigned long pfn; 159 unsigned long undo_pfn; 160 struct page *page; 161 162 BUG_ON((start_pfn) & (pageblock_nr_pages - 1)); 163 BUG_ON((end_pfn) & (pageblock_nr_pages - 1)); 164 165 for (pfn = start_pfn; 166 pfn < end_pfn; 167 pfn += pageblock_nr_pages) { 168 page = __first_valid_page(pfn, pageblock_nr_pages); 169 if (page && 170 set_migratetype_isolate(page, skip_hwpoisoned_pages)) { 171 undo_pfn = pfn; 172 goto undo; 173 } 174 } 175 return 0; 176 undo: 177 for (pfn = start_pfn; 178 pfn < undo_pfn; 179 pfn += pageblock_nr_pages) 180 unset_migratetype_isolate(pfn_to_page(pfn), migratetype); 181 182 return -EBUSY; 183 } 184 185 /* 186 * Make isolated pages available again. 187 */ 188 int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 189 unsigned migratetype) 190 { 191 unsigned long pfn; 192 struct page *page; 193 BUG_ON((start_pfn) & (pageblock_nr_pages - 1)); 194 BUG_ON((end_pfn) & (pageblock_nr_pages - 1)); 195 for (pfn = start_pfn; 196 pfn < end_pfn; 197 pfn += pageblock_nr_pages) { 198 page = __first_valid_page(pfn, pageblock_nr_pages); 199 if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE) 200 continue; 201 unset_migratetype_isolate(page, migratetype); 202 } 203 return 0; 204 } 205 /* 206 * Test all pages in the range is free(means isolated) or not. 207 * all pages in [start_pfn...end_pfn) must be in the same zone. 208 * zone->lock must be held before call this. 209 * 210 * Returns 1 if all pages in the range are isolated. 211 */ 212 static int 213 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, 214 bool skip_hwpoisoned_pages) 215 { 216 struct page *page; 217 218 while (pfn < end_pfn) { 219 if (!pfn_valid_within(pfn)) { 220 pfn++; 221 continue; 222 } 223 page = pfn_to_page(pfn); 224 if (PageBuddy(page)) { 225 /* 226 * If race between isolatation and allocation happens, 227 * some free pages could be in MIGRATE_MOVABLE list 228 * although pageblock's migratation type of the page 229 * is MIGRATE_ISOLATE. Catch it and move the page into 230 * MIGRATE_ISOLATE list. 231 */ 232 if (get_freepage_migratetype(page) != MIGRATE_ISOLATE) { 233 struct page *end_page; 234 235 end_page = page + (1 << page_order(page)) - 1; 236 move_freepages(page_zone(page), page, end_page, 237 MIGRATE_ISOLATE); 238 } 239 pfn += 1 << page_order(page); 240 } 241 else if (page_count(page) == 0 && 242 get_freepage_migratetype(page) == MIGRATE_ISOLATE) 243 pfn += 1; 244 else if (skip_hwpoisoned_pages && PageHWPoison(page)) { 245 /* 246 * The HWPoisoned page may be not in buddy 247 * system, and page_count() is not 0. 248 */ 249 pfn++; 250 continue; 251 } 252 else 253 break; 254 } 255 if (pfn < end_pfn) 256 return 0; 257 return 1; 258 } 259 260 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn, 261 bool skip_hwpoisoned_pages) 262 { 263 unsigned long pfn, flags; 264 struct page *page; 265 struct zone *zone; 266 int ret; 267 268 /* 269 * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages 270 * are not aligned to pageblock_nr_pages. 271 * Then we just check migratetype first. 272 */ 273 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { 274 page = __first_valid_page(pfn, pageblock_nr_pages); 275 if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE) 276 break; 277 } 278 page = __first_valid_page(start_pfn, end_pfn - start_pfn); 279 if ((pfn < end_pfn) || !page) 280 return -EBUSY; 281 /* Check all pages are free or marked as ISOLATED */ 282 zone = page_zone(page); 283 spin_lock_irqsave(&zone->lock, flags); 284 ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn, 285 skip_hwpoisoned_pages); 286 spin_unlock_irqrestore(&zone->lock, flags); 287 return ret ? 0 : -EBUSY; 288 } 289 290 struct page *alloc_migrate_target(struct page *page, unsigned long private, 291 int **resultp) 292 { 293 gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE; 294 295 /* 296 * TODO: allocate a destination hugepage from a nearest neighbor node, 297 * accordance with memory policy of the user process if possible. For 298 * now as a simple work-around, we use the next node for destination. 299 */ 300 if (PageHuge(page)) { 301 nodemask_t src = nodemask_of_node(page_to_nid(page)); 302 nodemask_t dst; 303 nodes_complement(dst, src); 304 return alloc_huge_page_node(page_hstate(compound_head(page)), 305 next_node(page_to_nid(page), dst)); 306 } 307 308 if (PageHighMem(page)) 309 gfp_mask |= __GFP_HIGHMEM; 310 311 return alloc_page(gfp_mask); 312 } 313