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/memcontrol.h> 14 #include <linux/sched/clock.h> 15 16 #include "internal.h" 17 18 /* 19 * TODO: teach PAGE_OWNER_STACK_DEPTH (__dump_page_owner and save_stack) 20 * to use off stack temporal storage 21 */ 22 #define PAGE_OWNER_STACK_DEPTH (16) 23 24 struct page_owner { 25 unsigned short order; 26 short last_migrate_reason; 27 gfp_t gfp_mask; 28 depot_stack_handle_t handle; 29 depot_stack_handle_t free_handle; 30 u64 ts_nsec; 31 u64 free_ts_nsec; 32 char comm[TASK_COMM_LEN]; 33 pid_t pid; 34 pid_t tgid; 35 pid_t free_pid; 36 pid_t free_tgid; 37 }; 38 39 struct stack { 40 struct stack_record *stack_record; 41 struct stack *next; 42 }; 43 static struct stack dummy_stack; 44 static struct stack failure_stack; 45 static struct stack *stack_list; 46 static DEFINE_SPINLOCK(stack_list_lock); 47 48 static bool page_owner_enabled __initdata; 49 DEFINE_STATIC_KEY_FALSE(page_owner_inited); 50 51 static depot_stack_handle_t dummy_handle; 52 static depot_stack_handle_t failure_handle; 53 static depot_stack_handle_t early_handle; 54 55 static void init_early_allocated_pages(void); 56 57 static inline void set_current_in_page_owner(void) 58 { 59 /* 60 * Avoid recursion. 61 * 62 * We might need to allocate more memory from page_owner code, so make 63 * sure to signal it in order to avoid recursion. 64 */ 65 current->in_page_owner = 1; 66 } 67 68 static inline void unset_current_in_page_owner(void) 69 { 70 current->in_page_owner = 0; 71 } 72 73 static int __init early_page_owner_param(char *buf) 74 { 75 int ret = kstrtobool(buf, &page_owner_enabled); 76 77 if (page_owner_enabled) 78 stack_depot_request_early_init(); 79 80 return ret; 81 } 82 early_param("page_owner", early_page_owner_param); 83 84 static __init bool need_page_owner(void) 85 { 86 return page_owner_enabled; 87 } 88 89 static __always_inline depot_stack_handle_t create_dummy_stack(void) 90 { 91 unsigned long entries[4]; 92 unsigned int nr_entries; 93 94 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0); 95 return stack_depot_save(entries, nr_entries, GFP_KERNEL); 96 } 97 98 static noinline void register_dummy_stack(void) 99 { 100 dummy_handle = create_dummy_stack(); 101 } 102 103 static noinline void register_failure_stack(void) 104 { 105 failure_handle = create_dummy_stack(); 106 } 107 108 static noinline void register_early_stack(void) 109 { 110 early_handle = create_dummy_stack(); 111 } 112 113 static __init void init_page_owner(void) 114 { 115 if (!page_owner_enabled) 116 return; 117 118 register_dummy_stack(); 119 register_failure_stack(); 120 register_early_stack(); 121 init_early_allocated_pages(); 122 /* Initialize dummy and failure stacks and link them to stack_list */ 123 dummy_stack.stack_record = __stack_depot_get_stack_record(dummy_handle); 124 failure_stack.stack_record = __stack_depot_get_stack_record(failure_handle); 125 if (dummy_stack.stack_record) 126 refcount_set(&dummy_stack.stack_record->count, 1); 127 if (failure_stack.stack_record) 128 refcount_set(&failure_stack.stack_record->count, 1); 129 dummy_stack.next = &failure_stack; 130 stack_list = &dummy_stack; 131 static_branch_enable(&page_owner_inited); 132 } 133 134 struct page_ext_operations page_owner_ops = { 135 .size = sizeof(struct page_owner), 136 .need = need_page_owner, 137 .init = init_page_owner, 138 .need_shared_flags = true, 139 }; 140 141 static inline struct page_owner *get_page_owner(struct page_ext *page_ext) 142 { 143 return page_ext_data(page_ext, &page_owner_ops); 144 } 145 146 static noinline depot_stack_handle_t save_stack(gfp_t flags) 147 { 148 unsigned long entries[PAGE_OWNER_STACK_DEPTH]; 149 depot_stack_handle_t handle; 150 unsigned int nr_entries; 151 152 if (current->in_page_owner) 153 return dummy_handle; 154 155 set_current_in_page_owner(); 156 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2); 157 handle = stack_depot_save(entries, nr_entries, flags); 158 if (!handle) 159 handle = failure_handle; 160 unset_current_in_page_owner(); 161 162 return handle; 163 } 164 165 static void add_stack_record_to_list(struct stack_record *stack_record, 166 gfp_t gfp_mask) 167 { 168 unsigned long flags; 169 struct stack *stack; 170 171 if (!gfpflags_allow_spinning(gfp_mask)) 172 return; 173 174 set_current_in_page_owner(); 175 stack = kmalloc(sizeof(*stack), gfp_nested_mask(gfp_mask)); 176 if (!stack) { 177 unset_current_in_page_owner(); 178 return; 179 } 180 unset_current_in_page_owner(); 181 182 stack->stack_record = stack_record; 183 stack->next = NULL; 184 185 spin_lock_irqsave(&stack_list_lock, flags); 186 stack->next = stack_list; 187 /* 188 * This pairs with smp_load_acquire() from function 189 * stack_start(). This guarantees that stack_start() 190 * will see an updated stack_list before starting to 191 * traverse the list. 192 */ 193 smp_store_release(&stack_list, stack); 194 spin_unlock_irqrestore(&stack_list_lock, flags); 195 } 196 197 static void inc_stack_record_count(depot_stack_handle_t handle, gfp_t gfp_mask, 198 int nr_base_pages) 199 { 200 struct stack_record *stack_record = __stack_depot_get_stack_record(handle); 201 202 if (!stack_record) 203 return; 204 205 /* 206 * New stack_record's that do not use STACK_DEPOT_FLAG_GET start 207 * with REFCOUNT_SATURATED to catch spurious increments of their 208 * refcount. 209 * Since we do not use STACK_DEPOT_FLAG_GET API, let us 210 * set a refcount of 1 ourselves. 211 */ 212 if (refcount_read(&stack_record->count) == REFCOUNT_SATURATED) { 213 int old = REFCOUNT_SATURATED; 214 215 if (atomic_try_cmpxchg_relaxed(&stack_record->count.refs, &old, 1)) 216 /* Add the new stack_record to our list */ 217 add_stack_record_to_list(stack_record, gfp_mask); 218 } 219 refcount_add(nr_base_pages, &stack_record->count); 220 } 221 222 static void dec_stack_record_count(depot_stack_handle_t handle, 223 int nr_base_pages) 224 { 225 struct stack_record *stack_record = __stack_depot_get_stack_record(handle); 226 227 if (!stack_record) 228 return; 229 230 if (refcount_sub_and_test(nr_base_pages, &stack_record->count)) 231 pr_warn("%s: refcount went to 0 for %u handle\n", __func__, 232 handle); 233 } 234 235 static inline void __update_page_owner_handle(struct page *page, 236 depot_stack_handle_t handle, 237 unsigned short order, 238 gfp_t gfp_mask, 239 short last_migrate_reason, u64 ts_nsec, 240 pid_t pid, pid_t tgid, char *comm) 241 { 242 struct page_ext_iter iter; 243 struct page_ext *page_ext; 244 struct page_owner *page_owner; 245 246 rcu_read_lock(); 247 for_each_page_ext(page, 1 << order, page_ext, iter) { 248 page_owner = get_page_owner(page_ext); 249 page_owner->handle = handle; 250 page_owner->order = order; 251 page_owner->gfp_mask = gfp_mask; 252 page_owner->last_migrate_reason = last_migrate_reason; 253 page_owner->pid = pid; 254 page_owner->tgid = tgid; 255 page_owner->ts_nsec = ts_nsec; 256 strscpy(page_owner->comm, comm, 257 sizeof(page_owner->comm)); 258 __set_bit(PAGE_EXT_OWNER, &page_ext->flags); 259 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags); 260 } 261 rcu_read_unlock(); 262 } 263 264 static inline void __update_page_owner_free_handle(struct page *page, 265 depot_stack_handle_t handle, 266 unsigned short order, 267 pid_t pid, pid_t tgid, 268 u64 free_ts_nsec) 269 { 270 struct page_ext_iter iter; 271 struct page_ext *page_ext; 272 struct page_owner *page_owner; 273 274 rcu_read_lock(); 275 for_each_page_ext(page, 1 << order, page_ext, iter) { 276 page_owner = get_page_owner(page_ext); 277 /* Only __reset_page_owner() wants to clear the bit */ 278 if (handle) { 279 __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags); 280 page_owner->free_handle = handle; 281 } 282 page_owner->free_ts_nsec = free_ts_nsec; 283 page_owner->free_pid = current->pid; 284 page_owner->free_tgid = current->tgid; 285 } 286 rcu_read_unlock(); 287 } 288 289 void __reset_page_owner(struct page *page, unsigned short order) 290 { 291 struct page_ext *page_ext; 292 depot_stack_handle_t handle; 293 depot_stack_handle_t alloc_handle; 294 struct page_owner *page_owner; 295 u64 free_ts_nsec = local_clock(); 296 297 page_ext = page_ext_get(page); 298 if (unlikely(!page_ext)) 299 return; 300 301 page_owner = get_page_owner(page_ext); 302 alloc_handle = page_owner->handle; 303 page_ext_put(page_ext); 304 305 /* 306 * Do not specify GFP_NOWAIT to make gfpflags_allow_spinning() == false 307 * to prevent issues in stack_depot_save(). 308 * This is similar to alloc_pages_nolock() gfp flags, but only used 309 * to signal stack_depot to avoid spin_locks. 310 */ 311 handle = save_stack(__GFP_NOWARN); 312 __update_page_owner_free_handle(page, handle, order, current->pid, 313 current->tgid, free_ts_nsec); 314 315 if (alloc_handle != early_handle) 316 /* 317 * early_handle is being set as a handle for all those 318 * early allocated pages. See init_pages_in_zone(). 319 * Since their refcount is not being incremented because 320 * the machinery is not ready yet, we cannot decrement 321 * their refcount either. 322 */ 323 dec_stack_record_count(alloc_handle, 1 << order); 324 } 325 326 noinline void __set_page_owner(struct page *page, unsigned short order, 327 gfp_t gfp_mask) 328 { 329 u64 ts_nsec = local_clock(); 330 depot_stack_handle_t handle; 331 332 handle = save_stack(gfp_mask); 333 __update_page_owner_handle(page, handle, order, gfp_mask, -1, 334 ts_nsec, current->pid, current->tgid, 335 current->comm); 336 inc_stack_record_count(handle, gfp_mask, 1 << order); 337 } 338 339 void __folio_set_owner_migrate_reason(struct folio *folio, int reason) 340 { 341 struct page_ext *page_ext = page_ext_get(&folio->page); 342 struct page_owner *page_owner; 343 344 if (unlikely(!page_ext)) 345 return; 346 347 page_owner = get_page_owner(page_ext); 348 page_owner->last_migrate_reason = reason; 349 page_ext_put(page_ext); 350 } 351 352 void __split_page_owner(struct page *page, int old_order, int new_order) 353 { 354 struct page_ext_iter iter; 355 struct page_ext *page_ext; 356 struct page_owner *page_owner; 357 358 rcu_read_lock(); 359 for_each_page_ext(page, 1 << old_order, page_ext, iter) { 360 page_owner = get_page_owner(page_ext); 361 page_owner->order = new_order; 362 } 363 rcu_read_unlock(); 364 } 365 366 void __folio_copy_owner(struct folio *newfolio, struct folio *old) 367 { 368 struct page_ext *page_ext; 369 struct page_ext_iter iter; 370 struct page_owner *old_page_owner; 371 struct page_owner *new_page_owner; 372 depot_stack_handle_t migrate_handle; 373 374 page_ext = page_ext_get(&old->page); 375 if (unlikely(!page_ext)) 376 return; 377 378 old_page_owner = get_page_owner(page_ext); 379 page_ext_put(page_ext); 380 381 page_ext = page_ext_get(&newfolio->page); 382 if (unlikely(!page_ext)) 383 return; 384 385 new_page_owner = get_page_owner(page_ext); 386 page_ext_put(page_ext); 387 388 migrate_handle = new_page_owner->handle; 389 __update_page_owner_handle(&newfolio->page, old_page_owner->handle, 390 old_page_owner->order, old_page_owner->gfp_mask, 391 old_page_owner->last_migrate_reason, 392 old_page_owner->ts_nsec, old_page_owner->pid, 393 old_page_owner->tgid, old_page_owner->comm); 394 /* 395 * Do not proactively clear PAGE_EXT_OWNER{_ALLOCATED} bits as the folio 396 * will be freed after migration. Keep them until then as they may be 397 * useful. 398 */ 399 __update_page_owner_free_handle(&newfolio->page, 0, old_page_owner->order, 400 old_page_owner->free_pid, 401 old_page_owner->free_tgid, 402 old_page_owner->free_ts_nsec); 403 /* 404 * We linked the original stack to the new folio, we need to do the same 405 * for the new one and the old folio otherwise there will be an imbalance 406 * when subtracting those pages from the stack. 407 */ 408 rcu_read_lock(); 409 for_each_page_ext(&old->page, 1 << new_page_owner->order, page_ext, iter) { 410 old_page_owner = get_page_owner(page_ext); 411 old_page_owner->handle = migrate_handle; 412 } 413 rcu_read_unlock(); 414 } 415 416 void pagetypeinfo_showmixedcount_print(struct seq_file *m, 417 pg_data_t *pgdat, struct zone *zone) 418 { 419 struct page *page; 420 struct page_ext *page_ext; 421 struct page_owner *page_owner; 422 unsigned long pfn, block_end_pfn; 423 unsigned long end_pfn = zone_end_pfn(zone); 424 unsigned long count[MIGRATE_TYPES] = { 0, }; 425 int pageblock_mt, page_mt; 426 int i; 427 428 /* Scan block by block. First and last block may be incomplete */ 429 pfn = zone->zone_start_pfn; 430 431 /* 432 * Walk the zone in pageblock_nr_pages steps. If a page block spans 433 * a zone boundary, it will be double counted between zones. This does 434 * not matter as the mixed block count will still be correct 435 */ 436 for (; pfn < end_pfn; ) { 437 page = pfn_to_online_page(pfn); 438 if (!page) { 439 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES); 440 continue; 441 } 442 443 block_end_pfn = pageblock_end_pfn(pfn); 444 block_end_pfn = min(block_end_pfn, end_pfn); 445 446 pageblock_mt = get_pageblock_migratetype(page); 447 448 for (; pfn < block_end_pfn; pfn++) { 449 /* The pageblock is online, no need to recheck. */ 450 page = pfn_to_page(pfn); 451 452 if (page_zone(page) != zone) 453 continue; 454 455 if (PageBuddy(page)) { 456 unsigned long freepage_order; 457 458 freepage_order = buddy_order_unsafe(page); 459 if (freepage_order <= MAX_PAGE_ORDER) 460 pfn += (1UL << freepage_order) - 1; 461 continue; 462 } 463 464 if (PageReserved(page)) 465 continue; 466 467 page_ext = page_ext_get(page); 468 if (unlikely(!page_ext)) 469 continue; 470 471 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags)) 472 goto ext_put_continue; 473 474 page_owner = get_page_owner(page_ext); 475 page_mt = gfp_migratetype(page_owner->gfp_mask); 476 if (pageblock_mt != page_mt) { 477 if (is_migrate_cma(pageblock_mt)) 478 count[MIGRATE_MOVABLE]++; 479 else 480 count[pageblock_mt]++; 481 482 pfn = block_end_pfn; 483 page_ext_put(page_ext); 484 break; 485 } 486 pfn += (1UL << page_owner->order) - 1; 487 ext_put_continue: 488 page_ext_put(page_ext); 489 } 490 } 491 492 /* Print counts */ 493 seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name); 494 for (i = 0; i < MIGRATE_TYPES; i++) 495 seq_printf(m, "%12lu ", count[i]); 496 seq_putc(m, '\n'); 497 } 498 499 /* 500 * Looking for memcg information and print it out 501 */ 502 static inline int print_page_owner_memcg(char *kbuf, size_t count, int ret, 503 struct page *page) 504 { 505 #ifdef CONFIG_MEMCG 506 unsigned long memcg_data; 507 struct mem_cgroup *memcg; 508 bool online; 509 char name[80]; 510 511 rcu_read_lock(); 512 memcg_data = READ_ONCE(page->memcg_data); 513 if (!memcg_data || PageTail(page)) 514 goto out_unlock; 515 516 if (memcg_data & MEMCG_DATA_OBJEXTS) 517 ret += scnprintf(kbuf + ret, count - ret, 518 "Slab cache page\n"); 519 520 memcg = page_memcg_check(page); 521 if (!memcg) 522 goto out_unlock; 523 524 online = (memcg->css.flags & CSS_ONLINE); 525 cgroup_name(memcg->css.cgroup, name, sizeof(name)); 526 ret += scnprintf(kbuf + ret, count - ret, 527 "Charged %sto %smemcg %s\n", 528 PageMemcgKmem(page) ? "(via objcg) " : "", 529 online ? "" : "offline ", 530 name); 531 out_unlock: 532 rcu_read_unlock(); 533 #endif /* CONFIG_MEMCG */ 534 535 return ret; 536 } 537 538 static ssize_t 539 print_page_owner(char __user *buf, size_t count, unsigned long pfn, 540 struct page *page, struct page_owner *page_owner, 541 depot_stack_handle_t handle) 542 { 543 int ret, pageblock_mt, page_mt; 544 char *kbuf; 545 546 count = min_t(size_t, count, PAGE_SIZE); 547 kbuf = kmalloc(count, GFP_KERNEL); 548 if (!kbuf) 549 return -ENOMEM; 550 551 ret = scnprintf(kbuf, count, 552 "Page allocated via order %u, mask %#x(%pGg), pid %d, tgid %d (%s), ts %llu ns\n", 553 page_owner->order, page_owner->gfp_mask, 554 &page_owner->gfp_mask, page_owner->pid, 555 page_owner->tgid, page_owner->comm, 556 page_owner->ts_nsec); 557 558 /* Print information relevant to grouping pages by mobility */ 559 pageblock_mt = get_pageblock_migratetype(page); 560 page_mt = gfp_migratetype(page_owner->gfp_mask); 561 ret += scnprintf(kbuf + ret, count - ret, 562 "PFN 0x%lx type %s Block %lu type %s Flags %pGp\n", 563 pfn, 564 migratetype_names[page_mt], 565 pfn >> pageblock_order, 566 migratetype_names[pageblock_mt], 567 &page->flags); 568 569 ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0); 570 if (ret >= count) 571 goto err; 572 573 if (page_owner->last_migrate_reason != -1) { 574 ret += scnprintf(kbuf + ret, count - ret, 575 "Page has been migrated, last migrate reason: %s\n", 576 migrate_reason_names[page_owner->last_migrate_reason]); 577 } 578 579 ret = print_page_owner_memcg(kbuf, count, ret, page); 580 581 ret += snprintf(kbuf + ret, count - ret, "\n"); 582 if (ret >= count) 583 goto err; 584 585 if (copy_to_user(buf, kbuf, ret)) 586 ret = -EFAULT; 587 588 kfree(kbuf); 589 return ret; 590 591 err: 592 kfree(kbuf); 593 return -ENOMEM; 594 } 595 596 void __dump_page_owner(const struct page *page) 597 { 598 struct page_ext *page_ext = page_ext_get((void *)page); 599 struct page_owner *page_owner; 600 depot_stack_handle_t handle; 601 gfp_t gfp_mask; 602 int mt; 603 604 if (unlikely(!page_ext)) { 605 pr_alert("There is not page extension available.\n"); 606 return; 607 } 608 609 page_owner = get_page_owner(page_ext); 610 gfp_mask = page_owner->gfp_mask; 611 mt = gfp_migratetype(gfp_mask); 612 613 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) { 614 pr_alert("page_owner info is not present (never set?)\n"); 615 page_ext_put(page_ext); 616 return; 617 } 618 619 if (test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags)) 620 pr_alert("page_owner tracks the page as allocated\n"); 621 else 622 pr_alert("page_owner tracks the page as freed\n"); 623 624 pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg), pid %d, tgid %d (%s), ts %llu, free_ts %llu\n", 625 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask, 626 page_owner->pid, page_owner->tgid, page_owner->comm, 627 page_owner->ts_nsec, page_owner->free_ts_nsec); 628 629 handle = READ_ONCE(page_owner->handle); 630 if (!handle) 631 pr_alert("page_owner allocation stack trace missing\n"); 632 else 633 stack_depot_print(handle); 634 635 handle = READ_ONCE(page_owner->free_handle); 636 if (!handle) { 637 pr_alert("page_owner free stack trace missing\n"); 638 } else { 639 pr_alert("page last free pid %d tgid %d stack trace:\n", 640 page_owner->free_pid, page_owner->free_tgid); 641 stack_depot_print(handle); 642 } 643 644 if (page_owner->last_migrate_reason != -1) 645 pr_alert("page has been migrated, last migrate reason: %s\n", 646 migrate_reason_names[page_owner->last_migrate_reason]); 647 page_ext_put(page_ext); 648 } 649 650 static ssize_t 651 read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) 652 { 653 unsigned long pfn; 654 struct page *page; 655 struct page_ext *page_ext; 656 struct page_owner *page_owner; 657 depot_stack_handle_t handle; 658 659 if (!static_branch_unlikely(&page_owner_inited)) 660 return -EINVAL; 661 662 page = NULL; 663 if (*ppos == 0) 664 pfn = min_low_pfn; 665 else 666 pfn = *ppos; 667 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */ 668 while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0) 669 pfn++; 670 671 /* Find an allocated page */ 672 for (; pfn < max_pfn; pfn++) { 673 /* 674 * This temporary page_owner is required so 675 * that we can avoid the context switches while holding 676 * the rcu lock and copying the page owner information to 677 * user through copy_to_user() or GFP_KERNEL allocations. 678 */ 679 struct page_owner page_owner_tmp; 680 681 /* 682 * If the new page is in a new MAX_ORDER_NR_PAGES area, 683 * validate the area as existing, skip it if not 684 */ 685 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) { 686 pfn += MAX_ORDER_NR_PAGES - 1; 687 continue; 688 } 689 690 page = pfn_to_page(pfn); 691 if (PageBuddy(page)) { 692 unsigned long freepage_order = buddy_order_unsafe(page); 693 694 if (freepage_order <= MAX_PAGE_ORDER) 695 pfn += (1UL << freepage_order) - 1; 696 continue; 697 } 698 699 page_ext = page_ext_get(page); 700 if (unlikely(!page_ext)) 701 continue; 702 703 /* 704 * Some pages could be missed by concurrent allocation or free, 705 * because we don't hold the zone lock. 706 */ 707 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) 708 goto ext_put_continue; 709 710 /* 711 * Although we do have the info about past allocation of free 712 * pages, it's not relevant for current memory usage. 713 */ 714 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags)) 715 goto ext_put_continue; 716 717 page_owner = get_page_owner(page_ext); 718 719 /* 720 * Don't print "tail" pages of high-order allocations as that 721 * would inflate the stats. 722 */ 723 if (!IS_ALIGNED(pfn, 1 << page_owner->order)) 724 goto ext_put_continue; 725 726 /* 727 * Access to page_ext->handle isn't synchronous so we should 728 * be careful to access it. 729 */ 730 handle = READ_ONCE(page_owner->handle); 731 if (!handle) 732 goto ext_put_continue; 733 734 /* Record the next PFN to read in the file offset */ 735 *ppos = pfn + 1; 736 737 page_owner_tmp = *page_owner; 738 page_ext_put(page_ext); 739 return print_page_owner(buf, count, pfn, page, 740 &page_owner_tmp, handle); 741 ext_put_continue: 742 page_ext_put(page_ext); 743 } 744 745 return 0; 746 } 747 748 static loff_t lseek_page_owner(struct file *file, loff_t offset, int orig) 749 { 750 switch (orig) { 751 case SEEK_SET: 752 file->f_pos = offset; 753 break; 754 case SEEK_CUR: 755 file->f_pos += offset; 756 break; 757 default: 758 return -EINVAL; 759 } 760 return file->f_pos; 761 } 762 763 static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone) 764 { 765 unsigned long pfn = zone->zone_start_pfn; 766 unsigned long end_pfn = zone_end_pfn(zone); 767 unsigned long count = 0; 768 769 /* 770 * Walk the zone in pageblock_nr_pages steps. If a page block spans 771 * a zone boundary, it will be double counted between zones. This does 772 * not matter as the mixed block count will still be correct 773 */ 774 for (; pfn < end_pfn; ) { 775 unsigned long block_end_pfn; 776 777 if (!pfn_valid(pfn)) { 778 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES); 779 continue; 780 } 781 782 block_end_pfn = pageblock_end_pfn(pfn); 783 block_end_pfn = min(block_end_pfn, end_pfn); 784 785 for (; pfn < block_end_pfn; pfn++) { 786 struct page *page = pfn_to_page(pfn); 787 struct page_ext *page_ext; 788 789 if (page_zone(page) != zone) 790 continue; 791 792 /* 793 * To avoid having to grab zone->lock, be a little 794 * careful when reading buddy page order. The only 795 * danger is that we skip too much and potentially miss 796 * some early allocated pages, which is better than 797 * heavy lock contention. 798 */ 799 if (PageBuddy(page)) { 800 unsigned long order = buddy_order_unsafe(page); 801 802 if (order > 0 && order <= MAX_PAGE_ORDER) 803 pfn += (1UL << order) - 1; 804 continue; 805 } 806 807 if (PageReserved(page)) 808 continue; 809 810 page_ext = page_ext_get(page); 811 if (unlikely(!page_ext)) 812 continue; 813 814 /* Maybe overlapping zone */ 815 if (test_bit(PAGE_EXT_OWNER, &page_ext->flags)) 816 goto ext_put_continue; 817 818 /* Found early allocated page */ 819 __update_page_owner_handle(page, early_handle, 0, 0, 820 -1, local_clock(), current->pid, 821 current->tgid, current->comm); 822 count++; 823 ext_put_continue: 824 page_ext_put(page_ext); 825 } 826 cond_resched(); 827 } 828 829 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n", 830 pgdat->node_id, zone->name, count); 831 } 832 833 static void init_zones_in_node(pg_data_t *pgdat) 834 { 835 struct zone *zone; 836 struct zone *node_zones = pgdat->node_zones; 837 838 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { 839 if (!populated_zone(zone)) 840 continue; 841 842 init_pages_in_zone(pgdat, zone); 843 } 844 } 845 846 static void init_early_allocated_pages(void) 847 { 848 pg_data_t *pgdat; 849 850 for_each_online_pgdat(pgdat) 851 init_zones_in_node(pgdat); 852 } 853 854 static const struct file_operations proc_page_owner_operations = { 855 .read = read_page_owner, 856 .llseek = lseek_page_owner, 857 }; 858 859 static void *stack_start(struct seq_file *m, loff_t *ppos) 860 { 861 struct stack *stack; 862 863 if (*ppos == -1UL) 864 return NULL; 865 866 if (!*ppos) { 867 /* 868 * This pairs with smp_store_release() from function 869 * add_stack_record_to_list(), so we get a consistent 870 * value of stack_list. 871 */ 872 stack = smp_load_acquire(&stack_list); 873 m->private = stack; 874 } else { 875 stack = m->private; 876 } 877 878 return stack; 879 } 880 881 static void *stack_next(struct seq_file *m, void *v, loff_t *ppos) 882 { 883 struct stack *stack = v; 884 885 stack = stack->next; 886 *ppos = stack ? *ppos + 1 : -1UL; 887 m->private = stack; 888 889 return stack; 890 } 891 892 static unsigned long page_owner_pages_threshold; 893 894 static int stack_print(struct seq_file *m, void *v) 895 { 896 int i, nr_base_pages; 897 struct stack *stack = v; 898 unsigned long *entries; 899 unsigned long nr_entries; 900 struct stack_record *stack_record = stack->stack_record; 901 902 if (!stack->stack_record) 903 return 0; 904 905 nr_entries = stack_record->size; 906 entries = stack_record->entries; 907 nr_base_pages = refcount_read(&stack_record->count) - 1; 908 909 if (nr_base_pages < 1 || nr_base_pages < page_owner_pages_threshold) 910 return 0; 911 912 for (i = 0; i < nr_entries; i++) 913 seq_printf(m, " %pS\n", (void *)entries[i]); 914 seq_printf(m, "nr_base_pages: %d\n\n", nr_base_pages); 915 916 return 0; 917 } 918 919 static void stack_stop(struct seq_file *m, void *v) 920 { 921 } 922 923 static const struct seq_operations page_owner_stack_op = { 924 .start = stack_start, 925 .next = stack_next, 926 .stop = stack_stop, 927 .show = stack_print 928 }; 929 930 static int page_owner_stack_open(struct inode *inode, struct file *file) 931 { 932 return seq_open_private(file, &page_owner_stack_op, 0); 933 } 934 935 static const struct file_operations page_owner_stack_operations = { 936 .open = page_owner_stack_open, 937 .read = seq_read, 938 .llseek = seq_lseek, 939 .release = seq_release, 940 }; 941 942 static int page_owner_threshold_get(void *data, u64 *val) 943 { 944 *val = READ_ONCE(page_owner_pages_threshold); 945 return 0; 946 } 947 948 static int page_owner_threshold_set(void *data, u64 val) 949 { 950 WRITE_ONCE(page_owner_pages_threshold, val); 951 return 0; 952 } 953 954 DEFINE_SIMPLE_ATTRIBUTE(proc_page_owner_threshold, &page_owner_threshold_get, 955 &page_owner_threshold_set, "%llu"); 956 957 958 static int __init pageowner_init(void) 959 { 960 struct dentry *dir; 961 962 if (!static_branch_unlikely(&page_owner_inited)) { 963 pr_info("page_owner is disabled\n"); 964 return 0; 965 } 966 967 debugfs_create_file("page_owner", 0400, NULL, NULL, 968 &proc_page_owner_operations); 969 dir = debugfs_create_dir("page_owner_stacks", NULL); 970 debugfs_create_file("show_stacks", 0400, dir, NULL, 971 &page_owner_stack_operations); 972 debugfs_create_file("count_threshold", 0600, dir, NULL, 973 &proc_page_owner_threshold); 974 975 return 0; 976 } 977 late_initcall(pageowner_init) 978