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(zone); 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 (pfn_valid_within(page_to_pfn(buddy)) && 105 !is_migrate_isolate_page(buddy)) { 106 __isolate_free_page(page, order); 107 kernel_map_pages(page, (1 << order), 1); 108 set_page_refcounted(page); 109 isolated_page = page; 110 } 111 } 112 } 113 114 /* 115 * If we isolate freepage with more than pageblock_order, there 116 * should be no freepage in the range, so we could avoid costly 117 * pageblock scanning for freepage moving. 118 */ 119 if (!isolated_page) { 120 nr_pages = move_freepages_block(zone, page, migratetype); 121 __mod_zone_freepage_state(zone, nr_pages, migratetype); 122 } 123 set_pageblock_migratetype(page, migratetype); 124 zone->nr_isolate_pageblock--; 125 out: 126 spin_unlock_irqrestore(&zone->lock, flags); 127 if (isolated_page) 128 __free_pages(isolated_page, order); 129 } 130 131 static inline struct page * 132 __first_valid_page(unsigned long pfn, unsigned long nr_pages) 133 { 134 int i; 135 for (i = 0; i < nr_pages; i++) 136 if (pfn_valid_within(pfn + i)) 137 break; 138 if (unlikely(i == nr_pages)) 139 return NULL; 140 return pfn_to_page(pfn + i); 141 } 142 143 /* 144 * start_isolate_page_range() -- make page-allocation-type of range of pages 145 * to be MIGRATE_ISOLATE. 146 * @start_pfn: The lower PFN of the range to be isolated. 147 * @end_pfn: The upper PFN of the range to be isolated. 148 * @migratetype: migrate type to set in error recovery. 149 * 150 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in 151 * the range will never be allocated. Any free pages and pages freed in the 152 * future will not be allocated again. 153 * 154 * start_pfn/end_pfn must be aligned to pageblock_order. 155 * Returns 0 on success and -EBUSY if any part of range cannot be isolated. 156 */ 157 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 158 unsigned migratetype, bool skip_hwpoisoned_pages) 159 { 160 unsigned long pfn; 161 unsigned long undo_pfn; 162 struct page *page; 163 164 BUG_ON((start_pfn) & (pageblock_nr_pages - 1)); 165 BUG_ON((end_pfn) & (pageblock_nr_pages - 1)); 166 167 for (pfn = start_pfn; 168 pfn < end_pfn; 169 pfn += pageblock_nr_pages) { 170 page = __first_valid_page(pfn, pageblock_nr_pages); 171 if (page && 172 set_migratetype_isolate(page, skip_hwpoisoned_pages)) { 173 undo_pfn = pfn; 174 goto undo; 175 } 176 } 177 return 0; 178 undo: 179 for (pfn = start_pfn; 180 pfn < undo_pfn; 181 pfn += pageblock_nr_pages) 182 unset_migratetype_isolate(pfn_to_page(pfn), migratetype); 183 184 return -EBUSY; 185 } 186 187 /* 188 * Make isolated pages available again. 189 */ 190 int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 191 unsigned migratetype) 192 { 193 unsigned long pfn; 194 struct page *page; 195 BUG_ON((start_pfn) & (pageblock_nr_pages - 1)); 196 BUG_ON((end_pfn) & (pageblock_nr_pages - 1)); 197 for (pfn = start_pfn; 198 pfn < end_pfn; 199 pfn += pageblock_nr_pages) { 200 page = __first_valid_page(pfn, pageblock_nr_pages); 201 if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE) 202 continue; 203 unset_migratetype_isolate(page, migratetype); 204 } 205 return 0; 206 } 207 /* 208 * Test all pages in the range is free(means isolated) or not. 209 * all pages in [start_pfn...end_pfn) must be in the same zone. 210 * zone->lock must be held before call this. 211 * 212 * Returns 1 if all pages in the range are isolated. 213 */ 214 static int 215 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, 216 bool skip_hwpoisoned_pages) 217 { 218 struct page *page; 219 220 while (pfn < end_pfn) { 221 if (!pfn_valid_within(pfn)) { 222 pfn++; 223 continue; 224 } 225 page = pfn_to_page(pfn); 226 if (PageBuddy(page)) { 227 /* 228 * If race between isolatation and allocation happens, 229 * some free pages could be in MIGRATE_MOVABLE list 230 * although pageblock's migratation type of the page 231 * is MIGRATE_ISOLATE. Catch it and move the page into 232 * MIGRATE_ISOLATE list. 233 */ 234 if (get_freepage_migratetype(page) != MIGRATE_ISOLATE) { 235 struct page *end_page; 236 237 end_page = page + (1 << page_order(page)) - 1; 238 move_freepages(page_zone(page), page, end_page, 239 MIGRATE_ISOLATE); 240 } 241 pfn += 1 << page_order(page); 242 } 243 else if (page_count(page) == 0 && 244 get_freepage_migratetype(page) == MIGRATE_ISOLATE) 245 pfn += 1; 246 else if (skip_hwpoisoned_pages && PageHWPoison(page)) { 247 /* 248 * The HWPoisoned page may be not in buddy 249 * system, and page_count() is not 0. 250 */ 251 pfn++; 252 continue; 253 } 254 else 255 break; 256 } 257 if (pfn < end_pfn) 258 return 0; 259 return 1; 260 } 261 262 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn, 263 bool skip_hwpoisoned_pages) 264 { 265 unsigned long pfn, flags; 266 struct page *page; 267 struct zone *zone; 268 int ret; 269 270 /* 271 * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages 272 * are not aligned to pageblock_nr_pages. 273 * Then we just check migratetype first. 274 */ 275 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { 276 page = __first_valid_page(pfn, pageblock_nr_pages); 277 if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE) 278 break; 279 } 280 page = __first_valid_page(start_pfn, end_pfn - start_pfn); 281 if ((pfn < end_pfn) || !page) 282 return -EBUSY; 283 /* Check all pages are free or marked as ISOLATED */ 284 zone = page_zone(page); 285 spin_lock_irqsave(&zone->lock, flags); 286 ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn, 287 skip_hwpoisoned_pages); 288 spin_unlock_irqrestore(&zone->lock, flags); 289 return ret ? 0 : -EBUSY; 290 } 291 292 struct page *alloc_migrate_target(struct page *page, unsigned long private, 293 int **resultp) 294 { 295 gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE; 296 297 /* 298 * TODO: allocate a destination hugepage from a nearest neighbor node, 299 * accordance with memory policy of the user process if possible. For 300 * now as a simple work-around, we use the next node for destination. 301 */ 302 if (PageHuge(page)) { 303 nodemask_t src = nodemask_of_node(page_to_nid(page)); 304 nodemask_t dst; 305 nodes_complement(dst, src); 306 return alloc_huge_page_node(page_hstate(compound_head(page)), 307 next_node(page_to_nid(page), dst)); 308 } 309 310 if (PageHighMem(page)) 311 gfp_mask |= __GFP_HIGHMEM; 312 313 return alloc_page(gfp_mask); 314 } 315