1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/mm/page_isolation.c 4 */ 5 6 #include <linux/mm.h> 7 #include <linux/page-isolation.h> 8 #include <linux/pageblock-flags.h> 9 #include <linux/memory.h> 10 #include <linux/hugetlb.h> 11 #include <linux/page_owner.h> 12 #include <linux/migrate.h> 13 #include "internal.h" 14 15 #define CREATE_TRACE_POINTS 16 #include <trace/events/page_isolation.h> 17 18 static int set_migratetype_isolate(struct page *page, int migratetype, int isol_flags) 19 { 20 struct page *unmovable = NULL; 21 struct zone *zone; 22 unsigned long flags; 23 int ret = -EBUSY; 24 25 zone = page_zone(page); 26 27 spin_lock_irqsave(&zone->lock, flags); 28 29 /* 30 * We assume the caller intended to SET migrate type to isolate. 31 * If it is already set, then someone else must have raced and 32 * set it before us. Return -EBUSY 33 */ 34 if (is_migrate_isolate_page(page)) 35 goto out; 36 37 /* 38 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself. 39 * We just check MOVABLE pages. 40 */ 41 unmovable = has_unmovable_pages(zone, page, migratetype, isol_flags); 42 if (!unmovable) { 43 unsigned long nr_pages; 44 int mt = get_pageblock_migratetype(page); 45 46 set_pageblock_migratetype(page, MIGRATE_ISOLATE); 47 zone->nr_isolate_pageblock++; 48 nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE, 49 NULL); 50 51 __mod_zone_freepage_state(zone, -nr_pages, mt); 52 ret = 0; 53 } 54 55 out: 56 spin_unlock_irqrestore(&zone->lock, flags); 57 if (!ret) { 58 drain_all_pages(zone); 59 } else { 60 WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE); 61 62 if ((isol_flags & REPORT_FAILURE) && unmovable) 63 /* 64 * printk() with zone->lock held will likely trigger a 65 * lockdep splat, so defer it here. 66 */ 67 dump_page(unmovable, "unmovable page"); 68 } 69 70 return ret; 71 } 72 73 static void unset_migratetype_isolate(struct page *page, unsigned migratetype) 74 { 75 struct zone *zone; 76 unsigned long flags, nr_pages; 77 bool isolated_page = false; 78 unsigned int order; 79 unsigned long pfn, buddy_pfn; 80 struct page *buddy; 81 82 zone = page_zone(page); 83 spin_lock_irqsave(&zone->lock, flags); 84 if (!is_migrate_isolate_page(page)) 85 goto out; 86 87 /* 88 * Because freepage with more than pageblock_order on isolated 89 * pageblock is restricted to merge due to freepage counting problem, 90 * it is possible that there is free buddy page. 91 * move_freepages_block() doesn't care of merge so we need other 92 * approach in order to merge them. Isolation and free will make 93 * these pages to be merged. 94 */ 95 if (PageBuddy(page)) { 96 order = page_order(page); 97 if (order >= pageblock_order) { 98 pfn = page_to_pfn(page); 99 buddy_pfn = __find_buddy_pfn(pfn, order); 100 buddy = page + (buddy_pfn - pfn); 101 102 if (pfn_valid_within(buddy_pfn) && 103 !is_migrate_isolate_page(buddy)) { 104 __isolate_free_page(page, order); 105 isolated_page = true; 106 } 107 } 108 } 109 110 /* 111 * If we isolate freepage with more than pageblock_order, there 112 * should be no freepage in the range, so we could avoid costly 113 * pageblock scanning for freepage moving. 114 */ 115 if (!isolated_page) { 116 nr_pages = move_freepages_block(zone, page, migratetype, NULL); 117 __mod_zone_freepage_state(zone, nr_pages, migratetype); 118 } 119 set_pageblock_migratetype(page, migratetype); 120 zone->nr_isolate_pageblock--; 121 out: 122 spin_unlock_irqrestore(&zone->lock, flags); 123 if (isolated_page) { 124 post_alloc_hook(page, order, __GFP_MOVABLE); 125 __free_pages(page, order); 126 } 127 } 128 129 static inline struct page * 130 __first_valid_page(unsigned long pfn, unsigned long nr_pages) 131 { 132 int i; 133 134 for (i = 0; i < nr_pages; i++) { 135 struct page *page; 136 137 page = pfn_to_online_page(pfn + i); 138 if (!page) 139 continue; 140 return page; 141 } 142 return NULL; 143 } 144 145 /** 146 * start_isolate_page_range() - make page-allocation-type of range of pages to 147 * be MIGRATE_ISOLATE. 148 * @start_pfn: The lower PFN of the range to be isolated. 149 * @end_pfn: The upper PFN of the range to be isolated. 150 * start_pfn/end_pfn must be aligned to pageblock_order. 151 * @migratetype: Migrate type to set in error recovery. 152 * @flags: The following flags are allowed (they can be combined in 153 * a bit mask) 154 * MEMORY_OFFLINE - isolate to offline (!allocate) memory 155 * e.g., skip over PageHWPoison() pages 156 * REPORT_FAILURE - report details about the failure to 157 * isolate the range 158 * 159 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in 160 * the range will never be allocated. Any free pages and pages freed in the 161 * future will not be allocated again. If specified range includes migrate types 162 * other than MOVABLE or CMA, this will fail with -EBUSY. For isolating all 163 * pages in the range finally, the caller have to free all pages in the range. 164 * test_page_isolated() can be used for test it. 165 * 166 * There is no high level synchronization mechanism that prevents two threads 167 * from trying to isolate overlapping ranges. If this happens, one thread 168 * will notice pageblocks in the overlapping range already set to isolate. 169 * This happens in set_migratetype_isolate, and set_migratetype_isolate 170 * returns an error. We then clean up by restoring the migration type on 171 * pageblocks we may have modified and return -EBUSY to caller. This 172 * prevents two threads from simultaneously working on overlapping ranges. 173 * 174 * Return: the number of isolated pageblocks on success and -EBUSY if any part 175 * of range cannot be isolated. 176 */ 177 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 178 unsigned migratetype, int flags) 179 { 180 unsigned long pfn; 181 unsigned long undo_pfn; 182 struct page *page; 183 int nr_isolate_pageblock = 0; 184 185 BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages)); 186 BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages)); 187 188 for (pfn = start_pfn; 189 pfn < end_pfn; 190 pfn += pageblock_nr_pages) { 191 page = __first_valid_page(pfn, pageblock_nr_pages); 192 if (page) { 193 if (set_migratetype_isolate(page, migratetype, flags)) { 194 undo_pfn = pfn; 195 goto undo; 196 } 197 nr_isolate_pageblock++; 198 } 199 } 200 return nr_isolate_pageblock; 201 undo: 202 for (pfn = start_pfn; 203 pfn < undo_pfn; 204 pfn += pageblock_nr_pages) { 205 struct page *page = pfn_to_online_page(pfn); 206 if (!page) 207 continue; 208 unset_migratetype_isolate(page, migratetype); 209 } 210 211 return -EBUSY; 212 } 213 214 /* 215 * Make isolated pages available again. 216 */ 217 void undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 218 unsigned migratetype) 219 { 220 unsigned long pfn; 221 struct page *page; 222 223 BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages)); 224 BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages)); 225 226 for (pfn = start_pfn; 227 pfn < end_pfn; 228 pfn += pageblock_nr_pages) { 229 page = __first_valid_page(pfn, pageblock_nr_pages); 230 if (!page || !is_migrate_isolate_page(page)) 231 continue; 232 unset_migratetype_isolate(page, migratetype); 233 } 234 } 235 /* 236 * Test all pages in the range is free(means isolated) or not. 237 * all pages in [start_pfn...end_pfn) must be in the same zone. 238 * zone->lock must be held before call this. 239 * 240 * Returns the last tested pfn. 241 */ 242 static unsigned long 243 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, 244 int flags) 245 { 246 struct page *page; 247 248 while (pfn < end_pfn) { 249 if (!pfn_valid_within(pfn)) { 250 pfn++; 251 continue; 252 } 253 page = pfn_to_page(pfn); 254 if (PageBuddy(page)) 255 /* 256 * If the page is on a free list, it has to be on 257 * the correct MIGRATE_ISOLATE freelist. There is no 258 * simple way to verify that as VM_BUG_ON(), though. 259 */ 260 pfn += 1 << page_order(page); 261 else if ((flags & MEMORY_OFFLINE) && PageHWPoison(page)) 262 /* A HWPoisoned page cannot be also PageBuddy */ 263 pfn++; 264 else 265 break; 266 } 267 268 return pfn; 269 } 270 271 /* Caller should ensure that requested range is in a single zone */ 272 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn, 273 int isol_flags) 274 { 275 unsigned long pfn, flags; 276 struct page *page; 277 struct zone *zone; 278 279 /* 280 * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages 281 * are not aligned to pageblock_nr_pages. 282 * Then we just check migratetype first. 283 */ 284 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { 285 page = __first_valid_page(pfn, pageblock_nr_pages); 286 if (page && !is_migrate_isolate_page(page)) 287 break; 288 } 289 page = __first_valid_page(start_pfn, end_pfn - start_pfn); 290 if ((pfn < end_pfn) || !page) 291 return -EBUSY; 292 /* Check all pages are free or marked as ISOLATED */ 293 zone = page_zone(page); 294 spin_lock_irqsave(&zone->lock, flags); 295 pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn, isol_flags); 296 spin_unlock_irqrestore(&zone->lock, flags); 297 298 trace_test_pages_isolated(start_pfn, end_pfn, pfn); 299 300 return pfn < end_pfn ? -EBUSY : 0; 301 } 302 303 struct page *alloc_migrate_target(struct page *page, unsigned long private) 304 { 305 return new_page_nodemask(page, numa_node_id(), &node_states[N_MEMORY]); 306 } 307