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