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 nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE); 64 65 __mod_zone_freepage_state(zone, -nr_pages, migratetype); 66 } 67 68 spin_unlock_irqrestore(&zone->lock, flags); 69 if (!ret) 70 drain_all_pages(); 71 return ret; 72 } 73 74 void unset_migratetype_isolate(struct page *page, unsigned migratetype) 75 { 76 struct zone *zone; 77 unsigned long flags, nr_pages; 78 79 zone = page_zone(page); 80 spin_lock_irqsave(&zone->lock, flags); 81 if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE) 82 goto out; 83 nr_pages = move_freepages_block(zone, page, migratetype); 84 __mod_zone_freepage_state(zone, nr_pages, migratetype); 85 set_pageblock_migratetype(page, migratetype); 86 out: 87 spin_unlock_irqrestore(&zone->lock, flags); 88 } 89 90 static inline struct page * 91 __first_valid_page(unsigned long pfn, unsigned long nr_pages) 92 { 93 int i; 94 for (i = 0; i < nr_pages; i++) 95 if (pfn_valid_within(pfn + i)) 96 break; 97 if (unlikely(i == nr_pages)) 98 return NULL; 99 return pfn_to_page(pfn + i); 100 } 101 102 /* 103 * start_isolate_page_range() -- make page-allocation-type of range of pages 104 * to be MIGRATE_ISOLATE. 105 * @start_pfn: The lower PFN of the range to be isolated. 106 * @end_pfn: The upper PFN of the range to be isolated. 107 * @migratetype: migrate type to set in error recovery. 108 * 109 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in 110 * the range will never be allocated. Any free pages and pages freed in the 111 * future will not be allocated again. 112 * 113 * start_pfn/end_pfn must be aligned to pageblock_order. 114 * Returns 0 on success and -EBUSY if any part of range cannot be isolated. 115 */ 116 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 117 unsigned migratetype, bool skip_hwpoisoned_pages) 118 { 119 unsigned long pfn; 120 unsigned long undo_pfn; 121 struct page *page; 122 123 BUG_ON((start_pfn) & (pageblock_nr_pages - 1)); 124 BUG_ON((end_pfn) & (pageblock_nr_pages - 1)); 125 126 for (pfn = start_pfn; 127 pfn < end_pfn; 128 pfn += pageblock_nr_pages) { 129 page = __first_valid_page(pfn, pageblock_nr_pages); 130 if (page && 131 set_migratetype_isolate(page, skip_hwpoisoned_pages)) { 132 undo_pfn = pfn; 133 goto undo; 134 } 135 } 136 return 0; 137 undo: 138 for (pfn = start_pfn; 139 pfn < undo_pfn; 140 pfn += pageblock_nr_pages) 141 unset_migratetype_isolate(pfn_to_page(pfn), migratetype); 142 143 return -EBUSY; 144 } 145 146 /* 147 * Make isolated pages available again. 148 */ 149 int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 150 unsigned migratetype) 151 { 152 unsigned long pfn; 153 struct page *page; 154 BUG_ON((start_pfn) & (pageblock_nr_pages - 1)); 155 BUG_ON((end_pfn) & (pageblock_nr_pages - 1)); 156 for (pfn = start_pfn; 157 pfn < end_pfn; 158 pfn += pageblock_nr_pages) { 159 page = __first_valid_page(pfn, pageblock_nr_pages); 160 if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE) 161 continue; 162 unset_migratetype_isolate(page, migratetype); 163 } 164 return 0; 165 } 166 /* 167 * Test all pages in the range is free(means isolated) or not. 168 * all pages in [start_pfn...end_pfn) must be in the same zone. 169 * zone->lock must be held before call this. 170 * 171 * Returns 1 if all pages in the range are isolated. 172 */ 173 static int 174 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, 175 bool skip_hwpoisoned_pages) 176 { 177 struct page *page; 178 179 while (pfn < end_pfn) { 180 if (!pfn_valid_within(pfn)) { 181 pfn++; 182 continue; 183 } 184 page = pfn_to_page(pfn); 185 if (PageBuddy(page)) { 186 /* 187 * If race between isolatation and allocation happens, 188 * some free pages could be in MIGRATE_MOVABLE list 189 * although pageblock's migratation type of the page 190 * is MIGRATE_ISOLATE. Catch it and move the page into 191 * MIGRATE_ISOLATE list. 192 */ 193 if (get_freepage_migratetype(page) != MIGRATE_ISOLATE) { 194 struct page *end_page; 195 196 end_page = page + (1 << page_order(page)) - 1; 197 move_freepages(page_zone(page), page, end_page, 198 MIGRATE_ISOLATE); 199 } 200 pfn += 1 << page_order(page); 201 } 202 else if (page_count(page) == 0 && 203 get_freepage_migratetype(page) == MIGRATE_ISOLATE) 204 pfn += 1; 205 else if (skip_hwpoisoned_pages && PageHWPoison(page)) { 206 /* 207 * The HWPoisoned page may be not in buddy 208 * system, and page_count() is not 0. 209 */ 210 pfn++; 211 continue; 212 } 213 else 214 break; 215 } 216 if (pfn < end_pfn) 217 return 0; 218 return 1; 219 } 220 221 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn, 222 bool skip_hwpoisoned_pages) 223 { 224 unsigned long pfn, flags; 225 struct page *page; 226 struct zone *zone; 227 int ret; 228 229 /* 230 * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages 231 * are not aligned to pageblock_nr_pages. 232 * Then we just check migratetype first. 233 */ 234 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { 235 page = __first_valid_page(pfn, pageblock_nr_pages); 236 if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE) 237 break; 238 } 239 page = __first_valid_page(start_pfn, end_pfn - start_pfn); 240 if ((pfn < end_pfn) || !page) 241 return -EBUSY; 242 /* Check all pages are free or marked as ISOLATED */ 243 zone = page_zone(page); 244 spin_lock_irqsave(&zone->lock, flags); 245 ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn, 246 skip_hwpoisoned_pages); 247 spin_unlock_irqrestore(&zone->lock, flags); 248 return ret ? 0 : -EBUSY; 249 } 250 251 struct page *alloc_migrate_target(struct page *page, unsigned long private, 252 int **resultp) 253 { 254 gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE; 255 256 /* 257 * TODO: allocate a destination hugepage from a nearest neighbor node, 258 * accordance with memory policy of the user process if possible. For 259 * now as a simple work-around, we use the next node for destination. 260 */ 261 if (PageHuge(page)) { 262 nodemask_t src = nodemask_of_node(page_to_nid(page)); 263 nodemask_t dst; 264 nodes_complement(dst, src); 265 return alloc_huge_page_node(page_hstate(compound_head(page)), 266 next_node(page_to_nid(page), dst)); 267 } 268 269 if (PageHighMem(page)) 270 gfp_mask |= __GFP_HIGHMEM; 271 272 return alloc_page(gfp_mask); 273 } 274