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