1 #include <linux/debugfs.h> 2 #include <linux/mm.h> 3 #include <linux/slab.h> 4 #include <linux/uaccess.h> 5 #include <linux/bootmem.h> 6 #include <linux/stacktrace.h> 7 #include <linux/page_owner.h> 8 #include <linux/jump_label.h> 9 #include <linux/migrate.h> 10 #include "internal.h" 11 12 static bool page_owner_disabled = true; 13 DEFINE_STATIC_KEY_FALSE(page_owner_inited); 14 15 static void init_early_allocated_pages(void); 16 17 static int early_page_owner_param(char *buf) 18 { 19 if (!buf) 20 return -EINVAL; 21 22 if (strcmp(buf, "on") == 0) 23 page_owner_disabled = false; 24 25 return 0; 26 } 27 early_param("page_owner", early_page_owner_param); 28 29 static bool need_page_owner(void) 30 { 31 if (page_owner_disabled) 32 return false; 33 34 return true; 35 } 36 37 static void init_page_owner(void) 38 { 39 if (page_owner_disabled) 40 return; 41 42 static_branch_enable(&page_owner_inited); 43 init_early_allocated_pages(); 44 } 45 46 struct page_ext_operations page_owner_ops = { 47 .need = need_page_owner, 48 .init = init_page_owner, 49 }; 50 51 void __reset_page_owner(struct page *page, unsigned int order) 52 { 53 int i; 54 struct page_ext *page_ext; 55 56 for (i = 0; i < (1 << order); i++) { 57 page_ext = lookup_page_ext(page + i); 58 __clear_bit(PAGE_EXT_OWNER, &page_ext->flags); 59 } 60 } 61 62 void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask) 63 { 64 struct page_ext *page_ext = lookup_page_ext(page); 65 struct stack_trace trace = { 66 .nr_entries = 0, 67 .max_entries = ARRAY_SIZE(page_ext->trace_entries), 68 .entries = &page_ext->trace_entries[0], 69 .skip = 3, 70 }; 71 72 save_stack_trace(&trace); 73 74 page_ext->order = order; 75 page_ext->gfp_mask = gfp_mask; 76 page_ext->nr_entries = trace.nr_entries; 77 page_ext->last_migrate_reason = -1; 78 79 __set_bit(PAGE_EXT_OWNER, &page_ext->flags); 80 } 81 82 void __set_page_owner_migrate_reason(struct page *page, int reason) 83 { 84 struct page_ext *page_ext = lookup_page_ext(page); 85 86 page_ext->last_migrate_reason = reason; 87 } 88 89 gfp_t __get_page_owner_gfp(struct page *page) 90 { 91 struct page_ext *page_ext = lookup_page_ext(page); 92 93 return page_ext->gfp_mask; 94 } 95 96 void __copy_page_owner(struct page *oldpage, struct page *newpage) 97 { 98 struct page_ext *old_ext = lookup_page_ext(oldpage); 99 struct page_ext *new_ext = lookup_page_ext(newpage); 100 int i; 101 102 new_ext->order = old_ext->order; 103 new_ext->gfp_mask = old_ext->gfp_mask; 104 new_ext->nr_entries = old_ext->nr_entries; 105 106 for (i = 0; i < ARRAY_SIZE(new_ext->trace_entries); i++) 107 new_ext->trace_entries[i] = old_ext->trace_entries[i]; 108 109 /* 110 * We don't clear the bit on the oldpage as it's going to be freed 111 * after migration. Until then, the info can be useful in case of 112 * a bug, and the overal stats will be off a bit only temporarily. 113 * Also, migrate_misplaced_transhuge_page() can still fail the 114 * migration and then we want the oldpage to retain the info. But 115 * in that case we also don't need to explicitly clear the info from 116 * the new page, which will be freed. 117 */ 118 __set_bit(PAGE_EXT_OWNER, &new_ext->flags); 119 } 120 121 static ssize_t 122 print_page_owner(char __user *buf, size_t count, unsigned long pfn, 123 struct page *page, struct page_ext *page_ext) 124 { 125 int ret; 126 int pageblock_mt, page_mt; 127 char *kbuf; 128 struct stack_trace trace = { 129 .nr_entries = page_ext->nr_entries, 130 .entries = &page_ext->trace_entries[0], 131 }; 132 133 kbuf = kmalloc(count, GFP_KERNEL); 134 if (!kbuf) 135 return -ENOMEM; 136 137 ret = snprintf(kbuf, count, 138 "Page allocated via order %u, mask %#x(%pGg)\n", 139 page_ext->order, page_ext->gfp_mask, 140 &page_ext->gfp_mask); 141 142 if (ret >= count) 143 goto err; 144 145 /* Print information relevant to grouping pages by mobility */ 146 pageblock_mt = get_pfnblock_migratetype(page, pfn); 147 page_mt = gfpflags_to_migratetype(page_ext->gfp_mask); 148 ret += snprintf(kbuf + ret, count - ret, 149 "PFN %lu type %s Block %lu type %s Flags %#lx(%pGp)\n", 150 pfn, 151 migratetype_names[page_mt], 152 pfn >> pageblock_order, 153 migratetype_names[pageblock_mt], 154 page->flags, &page->flags); 155 156 if (ret >= count) 157 goto err; 158 159 ret += snprint_stack_trace(kbuf + ret, count - ret, &trace, 0); 160 if (ret >= count) 161 goto err; 162 163 if (page_ext->last_migrate_reason != -1) { 164 ret += snprintf(kbuf + ret, count - ret, 165 "Page has been migrated, last migrate reason: %s\n", 166 migrate_reason_names[page_ext->last_migrate_reason]); 167 if (ret >= count) 168 goto err; 169 } 170 171 ret += snprintf(kbuf + ret, count - ret, "\n"); 172 if (ret >= count) 173 goto err; 174 175 if (copy_to_user(buf, kbuf, ret)) 176 ret = -EFAULT; 177 178 kfree(kbuf); 179 return ret; 180 181 err: 182 kfree(kbuf); 183 return -ENOMEM; 184 } 185 186 void __dump_page_owner(struct page *page) 187 { 188 struct page_ext *page_ext = lookup_page_ext(page); 189 struct stack_trace trace = { 190 .nr_entries = page_ext->nr_entries, 191 .entries = &page_ext->trace_entries[0], 192 }; 193 gfp_t gfp_mask = page_ext->gfp_mask; 194 int mt = gfpflags_to_migratetype(gfp_mask); 195 196 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) { 197 pr_alert("page_owner info is not active (free page?)\n"); 198 return; 199 } 200 201 pr_alert("page allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n", 202 page_ext->order, migratetype_names[mt], gfp_mask, &gfp_mask); 203 print_stack_trace(&trace, 0); 204 205 if (page_ext->last_migrate_reason != -1) 206 pr_alert("page has been migrated, last migrate reason: %s\n", 207 migrate_reason_names[page_ext->last_migrate_reason]); 208 } 209 210 static ssize_t 211 read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) 212 { 213 unsigned long pfn; 214 struct page *page; 215 struct page_ext *page_ext; 216 217 if (!static_branch_unlikely(&page_owner_inited)) 218 return -EINVAL; 219 220 page = NULL; 221 pfn = min_low_pfn + *ppos; 222 223 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */ 224 while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0) 225 pfn++; 226 227 drain_all_pages(NULL); 228 229 /* Find an allocated page */ 230 for (; pfn < max_pfn; pfn++) { 231 /* 232 * If the new page is in a new MAX_ORDER_NR_PAGES area, 233 * validate the area as existing, skip it if not 234 */ 235 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) { 236 pfn += MAX_ORDER_NR_PAGES - 1; 237 continue; 238 } 239 240 /* Check for holes within a MAX_ORDER area */ 241 if (!pfn_valid_within(pfn)) 242 continue; 243 244 page = pfn_to_page(pfn); 245 if (PageBuddy(page)) { 246 unsigned long freepage_order = page_order_unsafe(page); 247 248 if (freepage_order < MAX_ORDER) 249 pfn += (1UL << freepage_order) - 1; 250 continue; 251 } 252 253 page_ext = lookup_page_ext(page); 254 255 /* 256 * Some pages could be missed by concurrent allocation or free, 257 * because we don't hold the zone lock. 258 */ 259 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) 260 continue; 261 262 /* Record the next PFN to read in the file offset */ 263 *ppos = (pfn - min_low_pfn) + 1; 264 265 return print_page_owner(buf, count, pfn, page, page_ext); 266 } 267 268 return 0; 269 } 270 271 static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone) 272 { 273 struct page *page; 274 struct page_ext *page_ext; 275 unsigned long pfn = zone->zone_start_pfn, block_end_pfn; 276 unsigned long end_pfn = pfn + zone->spanned_pages; 277 unsigned long count = 0; 278 279 /* Scan block by block. First and last block may be incomplete */ 280 pfn = zone->zone_start_pfn; 281 282 /* 283 * Walk the zone in pageblock_nr_pages steps. If a page block spans 284 * a zone boundary, it will be double counted between zones. This does 285 * not matter as the mixed block count will still be correct 286 */ 287 for (; pfn < end_pfn; ) { 288 if (!pfn_valid(pfn)) { 289 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES); 290 continue; 291 } 292 293 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages); 294 block_end_pfn = min(block_end_pfn, end_pfn); 295 296 page = pfn_to_page(pfn); 297 298 for (; pfn < block_end_pfn; pfn++) { 299 if (!pfn_valid_within(pfn)) 300 continue; 301 302 page = pfn_to_page(pfn); 303 304 /* 305 * We are safe to check buddy flag and order, because 306 * this is init stage and only single thread runs. 307 */ 308 if (PageBuddy(page)) { 309 pfn += (1UL << page_order(page)) - 1; 310 continue; 311 } 312 313 if (PageReserved(page)) 314 continue; 315 316 page_ext = lookup_page_ext(page); 317 318 /* Maybe overraping zone */ 319 if (test_bit(PAGE_EXT_OWNER, &page_ext->flags)) 320 continue; 321 322 /* Found early allocated page */ 323 set_page_owner(page, 0, 0); 324 count++; 325 } 326 } 327 328 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n", 329 pgdat->node_id, zone->name, count); 330 } 331 332 static void init_zones_in_node(pg_data_t *pgdat) 333 { 334 struct zone *zone; 335 struct zone *node_zones = pgdat->node_zones; 336 unsigned long flags; 337 338 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { 339 if (!populated_zone(zone)) 340 continue; 341 342 spin_lock_irqsave(&zone->lock, flags); 343 init_pages_in_zone(pgdat, zone); 344 spin_unlock_irqrestore(&zone->lock, flags); 345 } 346 } 347 348 static void init_early_allocated_pages(void) 349 { 350 pg_data_t *pgdat; 351 352 drain_all_pages(NULL); 353 for_each_online_pgdat(pgdat) 354 init_zones_in_node(pgdat); 355 } 356 357 static const struct file_operations proc_page_owner_operations = { 358 .read = read_page_owner, 359 }; 360 361 static int __init pageowner_init(void) 362 { 363 struct dentry *dentry; 364 365 if (!static_branch_unlikely(&page_owner_inited)) { 366 pr_info("page_owner is disabled\n"); 367 return 0; 368 } 369 370 dentry = debugfs_create_file("page_owner", S_IRUSR, NULL, 371 NULL, &proc_page_owner_operations); 372 if (IS_ERR(dentry)) 373 return PTR_ERR(dentry); 374 375 return 0; 376 } 377 late_initcall(pageowner_init) 378