1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/debugfs.h> 3 #include <linux/mm.h> 4 #include <linux/slab.h> 5 #include <linux/uaccess.h> 6 #include <linux/memblock.h> 7 #include <linux/stacktrace.h> 8 #include <linux/page_owner.h> 9 #include <linux/jump_label.h> 10 #include <linux/migrate.h> 11 #include <linux/stackdepot.h> 12 #include <linux/seq_file.h> 13 #include <linux/sched/clock.h> 14 15 #include "internal.h" 16 17 /* 18 * TODO: teach PAGE_OWNER_STACK_DEPTH (__dump_page_owner and save_stack) 19 * to use off stack temporal storage 20 */ 21 #define PAGE_OWNER_STACK_DEPTH (16) 22 23 struct page_owner { 24 unsigned short order; 25 short last_migrate_reason; 26 gfp_t gfp_mask; 27 depot_stack_handle_t handle; 28 depot_stack_handle_t free_handle; 29 u64 ts_nsec; 30 u64 free_ts_nsec; 31 pid_t pid; 32 }; 33 34 static bool page_owner_enabled = false; 35 DEFINE_STATIC_KEY_FALSE(page_owner_inited); 36 37 static depot_stack_handle_t dummy_handle; 38 static depot_stack_handle_t failure_handle; 39 static depot_stack_handle_t early_handle; 40 41 static void init_early_allocated_pages(void); 42 43 static int __init early_page_owner_param(char *buf) 44 { 45 return kstrtobool(buf, &page_owner_enabled); 46 } 47 early_param("page_owner", early_page_owner_param); 48 49 static bool need_page_owner(void) 50 { 51 return page_owner_enabled; 52 } 53 54 static __always_inline depot_stack_handle_t create_dummy_stack(void) 55 { 56 unsigned long entries[4]; 57 unsigned int nr_entries; 58 59 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0); 60 return stack_depot_save(entries, nr_entries, GFP_KERNEL); 61 } 62 63 static noinline void register_dummy_stack(void) 64 { 65 dummy_handle = create_dummy_stack(); 66 } 67 68 static noinline void register_failure_stack(void) 69 { 70 failure_handle = create_dummy_stack(); 71 } 72 73 static noinline void register_early_stack(void) 74 { 75 early_handle = create_dummy_stack(); 76 } 77 78 static void init_page_owner(void) 79 { 80 if (!page_owner_enabled) 81 return; 82 83 register_dummy_stack(); 84 register_failure_stack(); 85 register_early_stack(); 86 static_branch_enable(&page_owner_inited); 87 init_early_allocated_pages(); 88 } 89 90 struct page_ext_operations page_owner_ops = { 91 .size = sizeof(struct page_owner), 92 .need = need_page_owner, 93 .init = init_page_owner, 94 }; 95 96 static inline struct page_owner *get_page_owner(struct page_ext *page_ext) 97 { 98 return (void *)page_ext + page_owner_ops.offset; 99 } 100 101 static noinline depot_stack_handle_t save_stack(gfp_t flags) 102 { 103 unsigned long entries[PAGE_OWNER_STACK_DEPTH]; 104 depot_stack_handle_t handle; 105 unsigned int nr_entries; 106 107 /* 108 * Avoid recursion. 109 * 110 * Sometimes page metadata allocation tracking requires more 111 * memory to be allocated: 112 * - when new stack trace is saved to stack depot 113 * - when backtrace itself is calculated (ia64) 114 */ 115 if (current->in_page_owner) 116 return dummy_handle; 117 current->in_page_owner = 1; 118 119 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2); 120 handle = stack_depot_save(entries, nr_entries, flags); 121 if (!handle) 122 handle = failure_handle; 123 124 current->in_page_owner = 0; 125 return handle; 126 } 127 128 void __reset_page_owner(struct page *page, unsigned short order) 129 { 130 int i; 131 struct page_ext *page_ext; 132 depot_stack_handle_t handle; 133 struct page_owner *page_owner; 134 u64 free_ts_nsec = local_clock(); 135 136 page_ext = lookup_page_ext(page); 137 if (unlikely(!page_ext)) 138 return; 139 140 handle = save_stack(GFP_NOWAIT | __GFP_NOWARN); 141 for (i = 0; i < (1 << order); i++) { 142 __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags); 143 page_owner = get_page_owner(page_ext); 144 page_owner->free_handle = handle; 145 page_owner->free_ts_nsec = free_ts_nsec; 146 page_ext = page_ext_next(page_ext); 147 } 148 } 149 150 static inline void __set_page_owner_handle(struct page_ext *page_ext, 151 depot_stack_handle_t handle, 152 unsigned short order, gfp_t gfp_mask) 153 { 154 struct page_owner *page_owner; 155 int i; 156 157 for (i = 0; i < (1 << order); i++) { 158 page_owner = get_page_owner(page_ext); 159 page_owner->handle = handle; 160 page_owner->order = order; 161 page_owner->gfp_mask = gfp_mask; 162 page_owner->last_migrate_reason = -1; 163 page_owner->pid = current->pid; 164 page_owner->ts_nsec = local_clock(); 165 __set_bit(PAGE_EXT_OWNER, &page_ext->flags); 166 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags); 167 168 page_ext = page_ext_next(page_ext); 169 } 170 } 171 172 noinline void __set_page_owner(struct page *page, unsigned short order, 173 gfp_t gfp_mask) 174 { 175 struct page_ext *page_ext = lookup_page_ext(page); 176 depot_stack_handle_t handle; 177 178 if (unlikely(!page_ext)) 179 return; 180 181 handle = save_stack(gfp_mask); 182 __set_page_owner_handle(page_ext, handle, order, gfp_mask); 183 } 184 185 void __set_page_owner_migrate_reason(struct page *page, int reason) 186 { 187 struct page_ext *page_ext = lookup_page_ext(page); 188 struct page_owner *page_owner; 189 190 if (unlikely(!page_ext)) 191 return; 192 193 page_owner = get_page_owner(page_ext); 194 page_owner->last_migrate_reason = reason; 195 } 196 197 void __split_page_owner(struct page *page, unsigned int nr) 198 { 199 int i; 200 struct page_ext *page_ext = lookup_page_ext(page); 201 struct page_owner *page_owner; 202 203 if (unlikely(!page_ext)) 204 return; 205 206 for (i = 0; i < nr; i++) { 207 page_owner = get_page_owner(page_ext); 208 page_owner->order = 0; 209 page_ext = page_ext_next(page_ext); 210 } 211 } 212 213 void __folio_copy_owner(struct folio *newfolio, struct folio *old) 214 { 215 struct page_ext *old_ext = lookup_page_ext(&old->page); 216 struct page_ext *new_ext = lookup_page_ext(&newfolio->page); 217 struct page_owner *old_page_owner, *new_page_owner; 218 219 if (unlikely(!old_ext || !new_ext)) 220 return; 221 222 old_page_owner = get_page_owner(old_ext); 223 new_page_owner = get_page_owner(new_ext); 224 new_page_owner->order = old_page_owner->order; 225 new_page_owner->gfp_mask = old_page_owner->gfp_mask; 226 new_page_owner->last_migrate_reason = 227 old_page_owner->last_migrate_reason; 228 new_page_owner->handle = old_page_owner->handle; 229 new_page_owner->pid = old_page_owner->pid; 230 new_page_owner->ts_nsec = old_page_owner->ts_nsec; 231 new_page_owner->free_ts_nsec = old_page_owner->ts_nsec; 232 233 /* 234 * We don't clear the bit on the old folio as it's going to be freed 235 * after migration. Until then, the info can be useful in case of 236 * a bug, and the overall stats will be off a bit only temporarily. 237 * Also, migrate_misplaced_transhuge_page() can still fail the 238 * migration and then we want the old folio to retain the info. But 239 * in that case we also don't need to explicitly clear the info from 240 * the new page, which will be freed. 241 */ 242 __set_bit(PAGE_EXT_OWNER, &new_ext->flags); 243 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &new_ext->flags); 244 } 245 246 void pagetypeinfo_showmixedcount_print(struct seq_file *m, 247 pg_data_t *pgdat, struct zone *zone) 248 { 249 struct page *page; 250 struct page_ext *page_ext; 251 struct page_owner *page_owner; 252 unsigned long pfn, block_end_pfn; 253 unsigned long end_pfn = zone_end_pfn(zone); 254 unsigned long count[MIGRATE_TYPES] = { 0, }; 255 int pageblock_mt, page_mt; 256 int i; 257 258 /* Scan block by block. First and last block may be incomplete */ 259 pfn = zone->zone_start_pfn; 260 261 /* 262 * Walk the zone in pageblock_nr_pages steps. If a page block spans 263 * a zone boundary, it will be double counted between zones. This does 264 * not matter as the mixed block count will still be correct 265 */ 266 for (; pfn < end_pfn; ) { 267 page = pfn_to_online_page(pfn); 268 if (!page) { 269 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES); 270 continue; 271 } 272 273 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages); 274 block_end_pfn = min(block_end_pfn, end_pfn); 275 276 pageblock_mt = get_pageblock_migratetype(page); 277 278 for (; pfn < block_end_pfn; pfn++) { 279 /* The pageblock is online, no need to recheck. */ 280 page = pfn_to_page(pfn); 281 282 if (page_zone(page) != zone) 283 continue; 284 285 if (PageBuddy(page)) { 286 unsigned long freepage_order; 287 288 freepage_order = buddy_order_unsafe(page); 289 if (freepage_order < MAX_ORDER) 290 pfn += (1UL << freepage_order) - 1; 291 continue; 292 } 293 294 if (PageReserved(page)) 295 continue; 296 297 page_ext = lookup_page_ext(page); 298 if (unlikely(!page_ext)) 299 continue; 300 301 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags)) 302 continue; 303 304 page_owner = get_page_owner(page_ext); 305 page_mt = gfp_migratetype(page_owner->gfp_mask); 306 if (pageblock_mt != page_mt) { 307 if (is_migrate_cma(pageblock_mt)) 308 count[MIGRATE_MOVABLE]++; 309 else 310 count[pageblock_mt]++; 311 312 pfn = block_end_pfn; 313 break; 314 } 315 pfn += (1UL << page_owner->order) - 1; 316 } 317 } 318 319 /* Print counts */ 320 seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name); 321 for (i = 0; i < MIGRATE_TYPES; i++) 322 seq_printf(m, "%12lu ", count[i]); 323 seq_putc(m, '\n'); 324 } 325 326 static ssize_t 327 print_page_owner(char __user *buf, size_t count, unsigned long pfn, 328 struct page *page, struct page_owner *page_owner, 329 depot_stack_handle_t handle) 330 { 331 int ret, pageblock_mt, page_mt; 332 char *kbuf; 333 334 count = min_t(size_t, count, PAGE_SIZE); 335 kbuf = kmalloc(count, GFP_KERNEL); 336 if (!kbuf) 337 return -ENOMEM; 338 339 ret = snprintf(kbuf, count, 340 "Page allocated via order %u, mask %#x(%pGg), pid %d, ts %llu ns, free_ts %llu ns\n", 341 page_owner->order, page_owner->gfp_mask, 342 &page_owner->gfp_mask, page_owner->pid, 343 page_owner->ts_nsec, page_owner->free_ts_nsec); 344 345 if (ret >= count) 346 goto err; 347 348 /* Print information relevant to grouping pages by mobility */ 349 pageblock_mt = get_pageblock_migratetype(page); 350 page_mt = gfp_migratetype(page_owner->gfp_mask); 351 ret += snprintf(kbuf + ret, count - ret, 352 "PFN %lu type %s Block %lu type %s Flags %pGp\n", 353 pfn, 354 migratetype_names[page_mt], 355 pfn >> pageblock_order, 356 migratetype_names[pageblock_mt], 357 &page->flags); 358 359 if (ret >= count) 360 goto err; 361 362 ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0); 363 if (ret >= count) 364 goto err; 365 366 if (page_owner->last_migrate_reason != -1) { 367 ret += snprintf(kbuf + ret, count - ret, 368 "Page has been migrated, last migrate reason: %s\n", 369 migrate_reason_names[page_owner->last_migrate_reason]); 370 if (ret >= count) 371 goto err; 372 } 373 374 ret += snprintf(kbuf + ret, count - ret, "\n"); 375 if (ret >= count) 376 goto err; 377 378 if (copy_to_user(buf, kbuf, ret)) 379 ret = -EFAULT; 380 381 kfree(kbuf); 382 return ret; 383 384 err: 385 kfree(kbuf); 386 return -ENOMEM; 387 } 388 389 void __dump_page_owner(const struct page *page) 390 { 391 struct page_ext *page_ext = lookup_page_ext(page); 392 struct page_owner *page_owner; 393 depot_stack_handle_t handle; 394 gfp_t gfp_mask; 395 int mt; 396 397 if (unlikely(!page_ext)) { 398 pr_alert("There is not page extension available.\n"); 399 return; 400 } 401 402 page_owner = get_page_owner(page_ext); 403 gfp_mask = page_owner->gfp_mask; 404 mt = gfp_migratetype(gfp_mask); 405 406 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) { 407 pr_alert("page_owner info is not present (never set?)\n"); 408 return; 409 } 410 411 if (test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags)) 412 pr_alert("page_owner tracks the page as allocated\n"); 413 else 414 pr_alert("page_owner tracks the page as freed\n"); 415 416 pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg), pid %d, ts %llu, free_ts %llu\n", 417 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask, 418 page_owner->pid, page_owner->ts_nsec, page_owner->free_ts_nsec); 419 420 handle = READ_ONCE(page_owner->handle); 421 if (!handle) 422 pr_alert("page_owner allocation stack trace missing\n"); 423 else 424 stack_depot_print(handle); 425 426 handle = READ_ONCE(page_owner->free_handle); 427 if (!handle) { 428 pr_alert("page_owner free stack trace missing\n"); 429 } else { 430 pr_alert("page last free stack trace:\n"); 431 stack_depot_print(handle); 432 } 433 434 if (page_owner->last_migrate_reason != -1) 435 pr_alert("page has been migrated, last migrate reason: %s\n", 436 migrate_reason_names[page_owner->last_migrate_reason]); 437 } 438 439 static ssize_t 440 read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) 441 { 442 unsigned long pfn; 443 struct page *page; 444 struct page_ext *page_ext; 445 struct page_owner *page_owner; 446 depot_stack_handle_t handle; 447 448 if (!static_branch_unlikely(&page_owner_inited)) 449 return -EINVAL; 450 451 page = NULL; 452 pfn = min_low_pfn + *ppos; 453 454 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */ 455 while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0) 456 pfn++; 457 458 drain_all_pages(NULL); 459 460 /* Find an allocated page */ 461 for (; pfn < max_pfn; pfn++) { 462 /* 463 * If the new page is in a new MAX_ORDER_NR_PAGES area, 464 * validate the area as existing, skip it if not 465 */ 466 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) { 467 pfn += MAX_ORDER_NR_PAGES - 1; 468 continue; 469 } 470 471 page = pfn_to_page(pfn); 472 if (PageBuddy(page)) { 473 unsigned long freepage_order = buddy_order_unsafe(page); 474 475 if (freepage_order < MAX_ORDER) 476 pfn += (1UL << freepage_order) - 1; 477 continue; 478 } 479 480 page_ext = lookup_page_ext(page); 481 if (unlikely(!page_ext)) 482 continue; 483 484 /* 485 * Some pages could be missed by concurrent allocation or free, 486 * because we don't hold the zone lock. 487 */ 488 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) 489 continue; 490 491 /* 492 * Although we do have the info about past allocation of free 493 * pages, it's not relevant for current memory usage. 494 */ 495 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags)) 496 continue; 497 498 page_owner = get_page_owner(page_ext); 499 500 /* 501 * Don't print "tail" pages of high-order allocations as that 502 * would inflate the stats. 503 */ 504 if (!IS_ALIGNED(pfn, 1 << page_owner->order)) 505 continue; 506 507 /* 508 * Access to page_ext->handle isn't synchronous so we should 509 * be careful to access it. 510 */ 511 handle = READ_ONCE(page_owner->handle); 512 if (!handle) 513 continue; 514 515 /* Record the next PFN to read in the file offset */ 516 *ppos = (pfn - min_low_pfn) + 1; 517 518 return print_page_owner(buf, count, pfn, page, 519 page_owner, handle); 520 } 521 522 return 0; 523 } 524 525 static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone) 526 { 527 unsigned long pfn = zone->zone_start_pfn; 528 unsigned long end_pfn = zone_end_pfn(zone); 529 unsigned long count = 0; 530 531 /* 532 * Walk the zone in pageblock_nr_pages steps. If a page block spans 533 * a zone boundary, it will be double counted between zones. This does 534 * not matter as the mixed block count will still be correct 535 */ 536 for (; pfn < end_pfn; ) { 537 unsigned long block_end_pfn; 538 539 if (!pfn_valid(pfn)) { 540 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES); 541 continue; 542 } 543 544 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages); 545 block_end_pfn = min(block_end_pfn, end_pfn); 546 547 for (; pfn < block_end_pfn; pfn++) { 548 struct page *page = pfn_to_page(pfn); 549 struct page_ext *page_ext; 550 551 if (page_zone(page) != zone) 552 continue; 553 554 /* 555 * To avoid having to grab zone->lock, be a little 556 * careful when reading buddy page order. The only 557 * danger is that we skip too much and potentially miss 558 * some early allocated pages, which is better than 559 * heavy lock contention. 560 */ 561 if (PageBuddy(page)) { 562 unsigned long order = buddy_order_unsafe(page); 563 564 if (order > 0 && order < MAX_ORDER) 565 pfn += (1UL << order) - 1; 566 continue; 567 } 568 569 if (PageReserved(page)) 570 continue; 571 572 page_ext = lookup_page_ext(page); 573 if (unlikely(!page_ext)) 574 continue; 575 576 /* Maybe overlapping zone */ 577 if (test_bit(PAGE_EXT_OWNER, &page_ext->flags)) 578 continue; 579 580 /* Found early allocated page */ 581 __set_page_owner_handle(page_ext, early_handle, 582 0, 0); 583 count++; 584 } 585 cond_resched(); 586 } 587 588 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n", 589 pgdat->node_id, zone->name, count); 590 } 591 592 static void init_zones_in_node(pg_data_t *pgdat) 593 { 594 struct zone *zone; 595 struct zone *node_zones = pgdat->node_zones; 596 597 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { 598 if (!populated_zone(zone)) 599 continue; 600 601 init_pages_in_zone(pgdat, zone); 602 } 603 } 604 605 static void init_early_allocated_pages(void) 606 { 607 pg_data_t *pgdat; 608 609 for_each_online_pgdat(pgdat) 610 init_zones_in_node(pgdat); 611 } 612 613 static const struct file_operations proc_page_owner_operations = { 614 .read = read_page_owner, 615 }; 616 617 static int __init pageowner_init(void) 618 { 619 if (!static_branch_unlikely(&page_owner_inited)) { 620 pr_info("page_owner is disabled\n"); 621 return 0; 622 } 623 624 debugfs_create_file("page_owner", 0400, NULL, NULL, 625 &proc_page_owner_operations); 626 627 return 0; 628 } 629 late_initcall(pageowner_init) 630