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 if (isolated_page) 121 __putback_isolated_page(page, order, migratetype); 122 zone->nr_isolate_pageblock--; 123 out: 124 spin_unlock_irqrestore(&zone->lock, flags); 125 } 126 127 static inline struct page * 128 __first_valid_page(unsigned long pfn, unsigned long nr_pages) 129 { 130 int i; 131 132 for (i = 0; i < nr_pages; i++) { 133 struct page *page; 134 135 page = pfn_to_online_page(pfn + i); 136 if (!page) 137 continue; 138 return page; 139 } 140 return NULL; 141 } 142 143 /** 144 * start_isolate_page_range() - make page-allocation-type of range of pages to 145 * 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 * start_pfn/end_pfn must be aligned to pageblock_order. 149 * @migratetype: Migrate type to set in error recovery. 150 * @flags: The following flags are allowed (they can be combined in 151 * a bit mask) 152 * MEMORY_OFFLINE - isolate to offline (!allocate) memory 153 * e.g., skip over PageHWPoison() pages 154 * and PageOffline() pages. 155 * REPORT_FAILURE - report details about the failure to 156 * isolate the range 157 * 158 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in 159 * the range will never be allocated. Any free pages and pages freed in the 160 * future will not be allocated again. If specified range includes migrate types 161 * other than MOVABLE or CMA, this will fail with -EBUSY. For isolating all 162 * pages in the range finally, the caller have to free all pages in the range. 163 * test_page_isolated() can be used for test it. 164 * 165 * There is no high level synchronization mechanism that prevents two threads 166 * from trying to isolate overlapping ranges. If this happens, one thread 167 * will notice pageblocks in the overlapping range already set to isolate. 168 * This happens in set_migratetype_isolate, and set_migratetype_isolate 169 * returns an error. We then clean up by restoring the migration type on 170 * pageblocks we may have modified and return -EBUSY to caller. This 171 * prevents two threads from simultaneously working on overlapping ranges. 172 * 173 * Return: the number of isolated pageblocks on success and -EBUSY if any part 174 * of range cannot be isolated. 175 */ 176 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 177 unsigned migratetype, int flags) 178 { 179 unsigned long pfn; 180 unsigned long undo_pfn; 181 struct page *page; 182 int nr_isolate_pageblock = 0; 183 184 BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages)); 185 BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages)); 186 187 for (pfn = start_pfn; 188 pfn < end_pfn; 189 pfn += pageblock_nr_pages) { 190 page = __first_valid_page(pfn, pageblock_nr_pages); 191 if (page) { 192 if (set_migratetype_isolate(page, migratetype, flags)) { 193 undo_pfn = pfn; 194 goto undo; 195 } 196 nr_isolate_pageblock++; 197 } 198 } 199 return nr_isolate_pageblock; 200 undo: 201 for (pfn = start_pfn; 202 pfn < undo_pfn; 203 pfn += pageblock_nr_pages) { 204 struct page *page = pfn_to_online_page(pfn); 205 if (!page) 206 continue; 207 unset_migratetype_isolate(page, migratetype); 208 } 209 210 return -EBUSY; 211 } 212 213 /* 214 * Make isolated pages available again. 215 */ 216 void undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 217 unsigned migratetype) 218 { 219 unsigned long pfn; 220 struct page *page; 221 222 BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages)); 223 BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages)); 224 225 for (pfn = start_pfn; 226 pfn < end_pfn; 227 pfn += pageblock_nr_pages) { 228 page = __first_valid_page(pfn, pageblock_nr_pages); 229 if (!page || !is_migrate_isolate_page(page)) 230 continue; 231 unset_migratetype_isolate(page, migratetype); 232 } 233 } 234 /* 235 * Test all pages in the range is free(means isolated) or not. 236 * all pages in [start_pfn...end_pfn) must be in the same zone. 237 * zone->lock must be held before call this. 238 * 239 * Returns the last tested pfn. 240 */ 241 static unsigned long 242 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, 243 int flags) 244 { 245 struct page *page; 246 247 while (pfn < end_pfn) { 248 if (!pfn_valid_within(pfn)) { 249 pfn++; 250 continue; 251 } 252 page = pfn_to_page(pfn); 253 if (PageBuddy(page)) 254 /* 255 * If the page is on a free list, it has to be on 256 * the correct MIGRATE_ISOLATE freelist. There is no 257 * simple way to verify that as VM_BUG_ON(), though. 258 */ 259 pfn += 1 << page_order(page); 260 else if ((flags & MEMORY_OFFLINE) && PageHWPoison(page)) 261 /* A HWPoisoned page cannot be also PageBuddy */ 262 pfn++; 263 else if ((flags & MEMORY_OFFLINE) && PageOffline(page) && 264 !page_count(page)) 265 /* 266 * The responsible driver agreed to skip PageOffline() 267 * pages when offlining memory by dropping its 268 * reference in MEM_GOING_OFFLINE. 269 */ 270 pfn++; 271 else 272 break; 273 } 274 275 return pfn; 276 } 277 278 /* Caller should ensure that requested range is in a single zone */ 279 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn, 280 int isol_flags) 281 { 282 unsigned long pfn, flags; 283 struct page *page; 284 struct zone *zone; 285 286 /* 287 * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages 288 * are not aligned to pageblock_nr_pages. 289 * Then we just check migratetype first. 290 */ 291 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { 292 page = __first_valid_page(pfn, pageblock_nr_pages); 293 if (page && !is_migrate_isolate_page(page)) 294 break; 295 } 296 page = __first_valid_page(start_pfn, end_pfn - start_pfn); 297 if ((pfn < end_pfn) || !page) 298 return -EBUSY; 299 /* Check all pages are free or marked as ISOLATED */ 300 zone = page_zone(page); 301 spin_lock_irqsave(&zone->lock, flags); 302 pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn, isol_flags); 303 spin_unlock_irqrestore(&zone->lock, flags); 304 305 trace_test_pages_isolated(start_pfn, end_pfn, pfn); 306 307 return pfn < end_pfn ? -EBUSY : 0; 308 } 309