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 14 #include "internal.h" 15 16 /* 17 * TODO: teach PAGE_OWNER_STACK_DEPTH (__dump_page_owner and save_stack) 18 * to use off stack temporal storage 19 */ 20 #define PAGE_OWNER_STACK_DEPTH (16) 21 22 struct page_owner { 23 unsigned short order; 24 short last_migrate_reason; 25 gfp_t gfp_mask; 26 depot_stack_handle_t handle; 27 }; 28 29 static bool page_owner_disabled = true; 30 DEFINE_STATIC_KEY_FALSE(page_owner_inited); 31 32 static depot_stack_handle_t dummy_handle; 33 static depot_stack_handle_t failure_handle; 34 static depot_stack_handle_t early_handle; 35 36 static void init_early_allocated_pages(void); 37 38 static int __init early_page_owner_param(char *buf) 39 { 40 if (!buf) 41 return -EINVAL; 42 43 if (strcmp(buf, "on") == 0) 44 page_owner_disabled = false; 45 46 return 0; 47 } 48 early_param("page_owner", early_page_owner_param); 49 50 static bool need_page_owner(void) 51 { 52 if (page_owner_disabled) 53 return false; 54 55 return true; 56 } 57 58 static __always_inline depot_stack_handle_t create_dummy_stack(void) 59 { 60 unsigned long entries[4]; 61 struct stack_trace dummy; 62 63 dummy.nr_entries = 0; 64 dummy.max_entries = ARRAY_SIZE(entries); 65 dummy.entries = &entries[0]; 66 dummy.skip = 0; 67 68 save_stack_trace(&dummy); 69 return depot_save_stack(&dummy, GFP_KERNEL); 70 } 71 72 static noinline void register_dummy_stack(void) 73 { 74 dummy_handle = create_dummy_stack(); 75 } 76 77 static noinline void register_failure_stack(void) 78 { 79 failure_handle = create_dummy_stack(); 80 } 81 82 static noinline void register_early_stack(void) 83 { 84 early_handle = create_dummy_stack(); 85 } 86 87 static void init_page_owner(void) 88 { 89 if (page_owner_disabled) 90 return; 91 92 register_dummy_stack(); 93 register_failure_stack(); 94 register_early_stack(); 95 static_branch_enable(&page_owner_inited); 96 init_early_allocated_pages(); 97 } 98 99 struct page_ext_operations page_owner_ops = { 100 .size = sizeof(struct page_owner), 101 .need = need_page_owner, 102 .init = init_page_owner, 103 }; 104 105 static inline struct page_owner *get_page_owner(struct page_ext *page_ext) 106 { 107 return (void *)page_ext + page_owner_ops.offset; 108 } 109 110 void __reset_page_owner(struct page *page, unsigned int order) 111 { 112 int i; 113 struct page_ext *page_ext; 114 115 for (i = 0; i < (1 << order); i++) { 116 page_ext = lookup_page_ext(page + i); 117 if (unlikely(!page_ext)) 118 continue; 119 __clear_bit(PAGE_EXT_OWNER, &page_ext->flags); 120 } 121 } 122 123 static inline bool check_recursive_alloc(struct stack_trace *trace, 124 unsigned long ip) 125 { 126 int i; 127 128 if (!trace->nr_entries) 129 return false; 130 131 for (i = 0; i < trace->nr_entries; i++) { 132 if (trace->entries[i] == ip) 133 return true; 134 } 135 136 return false; 137 } 138 139 static noinline depot_stack_handle_t save_stack(gfp_t flags) 140 { 141 unsigned long entries[PAGE_OWNER_STACK_DEPTH]; 142 struct stack_trace trace = { 143 .nr_entries = 0, 144 .entries = entries, 145 .max_entries = PAGE_OWNER_STACK_DEPTH, 146 .skip = 2 147 }; 148 depot_stack_handle_t handle; 149 150 save_stack_trace(&trace); 151 if (trace.nr_entries != 0 && 152 trace.entries[trace.nr_entries-1] == ULONG_MAX) 153 trace.nr_entries--; 154 155 /* 156 * We need to check recursion here because our request to stackdepot 157 * could trigger memory allocation to save new entry. New memory 158 * allocation would reach here and call depot_save_stack() again 159 * if we don't catch it. There is still not enough memory in stackdepot 160 * so it would try to allocate memory again and loop forever. 161 */ 162 if (check_recursive_alloc(&trace, _RET_IP_)) 163 return dummy_handle; 164 165 handle = depot_save_stack(&trace, flags); 166 if (!handle) 167 handle = failure_handle; 168 169 return handle; 170 } 171 172 static inline void __set_page_owner_handle(struct page_ext *page_ext, 173 depot_stack_handle_t handle, unsigned int order, gfp_t gfp_mask) 174 { 175 struct page_owner *page_owner; 176 177 page_owner = get_page_owner(page_ext); 178 page_owner->handle = handle; 179 page_owner->order = order; 180 page_owner->gfp_mask = gfp_mask; 181 page_owner->last_migrate_reason = -1; 182 183 __set_bit(PAGE_EXT_OWNER, &page_ext->flags); 184 } 185 186 noinline void __set_page_owner(struct page *page, unsigned int order, 187 gfp_t gfp_mask) 188 { 189 struct page_ext *page_ext = lookup_page_ext(page); 190 depot_stack_handle_t handle; 191 192 if (unlikely(!page_ext)) 193 return; 194 195 handle = save_stack(gfp_mask); 196 __set_page_owner_handle(page_ext, handle, order, gfp_mask); 197 } 198 199 void __set_page_owner_migrate_reason(struct page *page, int reason) 200 { 201 struct page_ext *page_ext = lookup_page_ext(page); 202 struct page_owner *page_owner; 203 204 if (unlikely(!page_ext)) 205 return; 206 207 page_owner = get_page_owner(page_ext); 208 page_owner->last_migrate_reason = reason; 209 } 210 211 void __split_page_owner(struct page *page, unsigned int order) 212 { 213 int i; 214 struct page_ext *page_ext = lookup_page_ext(page); 215 struct page_owner *page_owner; 216 217 if (unlikely(!page_ext)) 218 return; 219 220 page_owner = get_page_owner(page_ext); 221 page_owner->order = 0; 222 for (i = 1; i < (1 << order); i++) 223 __copy_page_owner(page, page + i); 224 } 225 226 void __copy_page_owner(struct page *oldpage, struct page *newpage) 227 { 228 struct page_ext *old_ext = lookup_page_ext(oldpage); 229 struct page_ext *new_ext = lookup_page_ext(newpage); 230 struct page_owner *old_page_owner, *new_page_owner; 231 232 if (unlikely(!old_ext || !new_ext)) 233 return; 234 235 old_page_owner = get_page_owner(old_ext); 236 new_page_owner = get_page_owner(new_ext); 237 new_page_owner->order = old_page_owner->order; 238 new_page_owner->gfp_mask = old_page_owner->gfp_mask; 239 new_page_owner->last_migrate_reason = 240 old_page_owner->last_migrate_reason; 241 new_page_owner->handle = old_page_owner->handle; 242 243 /* 244 * We don't clear the bit on the oldpage as it's going to be freed 245 * after migration. Until then, the info can be useful in case of 246 * a bug, and the overal stats will be off a bit only temporarily. 247 * Also, migrate_misplaced_transhuge_page() can still fail the 248 * migration and then we want the oldpage to retain the info. But 249 * in that case we also don't need to explicitly clear the info from 250 * the new page, which will be freed. 251 */ 252 __set_bit(PAGE_EXT_OWNER, &new_ext->flags); 253 } 254 255 void pagetypeinfo_showmixedcount_print(struct seq_file *m, 256 pg_data_t *pgdat, struct zone *zone) 257 { 258 struct page *page; 259 struct page_ext *page_ext; 260 struct page_owner *page_owner; 261 unsigned long pfn = zone->zone_start_pfn, block_end_pfn; 262 unsigned long end_pfn = pfn + zone->spanned_pages; 263 unsigned long count[MIGRATE_TYPES] = { 0, }; 264 int pageblock_mt, page_mt; 265 int i; 266 267 /* Scan block by block. First and last block may be incomplete */ 268 pfn = zone->zone_start_pfn; 269 270 /* 271 * Walk the zone in pageblock_nr_pages steps. If a page block spans 272 * a zone boundary, it will be double counted between zones. This does 273 * not matter as the mixed block count will still be correct 274 */ 275 for (; pfn < end_pfn; ) { 276 if (!pfn_valid(pfn)) { 277 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES); 278 continue; 279 } 280 281 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages); 282 block_end_pfn = min(block_end_pfn, end_pfn); 283 284 page = pfn_to_page(pfn); 285 pageblock_mt = get_pageblock_migratetype(page); 286 287 for (; pfn < block_end_pfn; pfn++) { 288 if (!pfn_valid_within(pfn)) 289 continue; 290 291 page = pfn_to_page(pfn); 292 293 if (page_zone(page) != zone) 294 continue; 295 296 if (PageBuddy(page)) { 297 unsigned long freepage_order; 298 299 freepage_order = page_order_unsafe(page); 300 if (freepage_order < MAX_ORDER) 301 pfn += (1UL << freepage_order) - 1; 302 continue; 303 } 304 305 if (PageReserved(page)) 306 continue; 307 308 page_ext = lookup_page_ext(page); 309 if (unlikely(!page_ext)) 310 continue; 311 312 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) 313 continue; 314 315 page_owner = get_page_owner(page_ext); 316 page_mt = gfpflags_to_migratetype( 317 page_owner->gfp_mask); 318 if (pageblock_mt != page_mt) { 319 if (is_migrate_cma(pageblock_mt)) 320 count[MIGRATE_MOVABLE]++; 321 else 322 count[pageblock_mt]++; 323 324 pfn = block_end_pfn; 325 break; 326 } 327 pfn += (1UL << page_owner->order) - 1; 328 } 329 } 330 331 /* Print counts */ 332 seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name); 333 for (i = 0; i < MIGRATE_TYPES; i++) 334 seq_printf(m, "%12lu ", count[i]); 335 seq_putc(m, '\n'); 336 } 337 338 static ssize_t 339 print_page_owner(char __user *buf, size_t count, unsigned long pfn, 340 struct page *page, struct page_owner *page_owner, 341 depot_stack_handle_t handle) 342 { 343 int ret; 344 int pageblock_mt, page_mt; 345 char *kbuf; 346 unsigned long entries[PAGE_OWNER_STACK_DEPTH]; 347 struct stack_trace trace = { 348 .nr_entries = 0, 349 .entries = entries, 350 .max_entries = PAGE_OWNER_STACK_DEPTH, 351 .skip = 0 352 }; 353 354 count = min_t(size_t, count, PAGE_SIZE); 355 kbuf = kmalloc(count, GFP_KERNEL); 356 if (!kbuf) 357 return -ENOMEM; 358 359 ret = snprintf(kbuf, count, 360 "Page allocated via order %u, mask %#x(%pGg)\n", 361 page_owner->order, page_owner->gfp_mask, 362 &page_owner->gfp_mask); 363 364 if (ret >= count) 365 goto err; 366 367 /* Print information relevant to grouping pages by mobility */ 368 pageblock_mt = get_pageblock_migratetype(page); 369 page_mt = gfpflags_to_migratetype(page_owner->gfp_mask); 370 ret += snprintf(kbuf + ret, count - ret, 371 "PFN %lu type %s Block %lu type %s Flags %#lx(%pGp)\n", 372 pfn, 373 migratetype_names[page_mt], 374 pfn >> pageblock_order, 375 migratetype_names[pageblock_mt], 376 page->flags, &page->flags); 377 378 if (ret >= count) 379 goto err; 380 381 depot_fetch_stack(handle, &trace); 382 ret += snprint_stack_trace(kbuf + ret, count - ret, &trace, 0); 383 if (ret >= count) 384 goto err; 385 386 if (page_owner->last_migrate_reason != -1) { 387 ret += snprintf(kbuf + ret, count - ret, 388 "Page has been migrated, last migrate reason: %s\n", 389 migrate_reason_names[page_owner->last_migrate_reason]); 390 if (ret >= count) 391 goto err; 392 } 393 394 ret += snprintf(kbuf + ret, count - ret, "\n"); 395 if (ret >= count) 396 goto err; 397 398 if (copy_to_user(buf, kbuf, ret)) 399 ret = -EFAULT; 400 401 kfree(kbuf); 402 return ret; 403 404 err: 405 kfree(kbuf); 406 return -ENOMEM; 407 } 408 409 void __dump_page_owner(struct page *page) 410 { 411 struct page_ext *page_ext = lookup_page_ext(page); 412 struct page_owner *page_owner; 413 unsigned long entries[PAGE_OWNER_STACK_DEPTH]; 414 struct stack_trace trace = { 415 .nr_entries = 0, 416 .entries = entries, 417 .max_entries = PAGE_OWNER_STACK_DEPTH, 418 .skip = 0 419 }; 420 depot_stack_handle_t handle; 421 gfp_t gfp_mask; 422 int mt; 423 424 if (unlikely(!page_ext)) { 425 pr_alert("There is not page extension available.\n"); 426 return; 427 } 428 429 page_owner = get_page_owner(page_ext); 430 gfp_mask = page_owner->gfp_mask; 431 mt = gfpflags_to_migratetype(gfp_mask); 432 433 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) { 434 pr_alert("page_owner info is not active (free page?)\n"); 435 return; 436 } 437 438 handle = READ_ONCE(page_owner->handle); 439 if (!handle) { 440 pr_alert("page_owner info is not active (free page?)\n"); 441 return; 442 } 443 444 depot_fetch_stack(handle, &trace); 445 pr_alert("page allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n", 446 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask); 447 print_stack_trace(&trace, 0); 448 449 if (page_owner->last_migrate_reason != -1) 450 pr_alert("page has been migrated, last migrate reason: %s\n", 451 migrate_reason_names[page_owner->last_migrate_reason]); 452 } 453 454 static ssize_t 455 read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) 456 { 457 unsigned long pfn; 458 struct page *page; 459 struct page_ext *page_ext; 460 struct page_owner *page_owner; 461 depot_stack_handle_t handle; 462 463 if (!static_branch_unlikely(&page_owner_inited)) 464 return -EINVAL; 465 466 page = NULL; 467 pfn = min_low_pfn + *ppos; 468 469 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */ 470 while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0) 471 pfn++; 472 473 drain_all_pages(NULL); 474 475 /* Find an allocated page */ 476 for (; pfn < max_pfn; pfn++) { 477 /* 478 * If the new page is in a new MAX_ORDER_NR_PAGES area, 479 * validate the area as existing, skip it if not 480 */ 481 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) { 482 pfn += MAX_ORDER_NR_PAGES - 1; 483 continue; 484 } 485 486 /* Check for holes within a MAX_ORDER area */ 487 if (!pfn_valid_within(pfn)) 488 continue; 489 490 page = pfn_to_page(pfn); 491 if (PageBuddy(page)) { 492 unsigned long freepage_order = page_order_unsafe(page); 493 494 if (freepage_order < MAX_ORDER) 495 pfn += (1UL << freepage_order) - 1; 496 continue; 497 } 498 499 page_ext = lookup_page_ext(page); 500 if (unlikely(!page_ext)) 501 continue; 502 503 /* 504 * Some pages could be missed by concurrent allocation or free, 505 * because we don't hold the zone lock. 506 */ 507 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) 508 continue; 509 510 page_owner = get_page_owner(page_ext); 511 512 /* 513 * Access to page_ext->handle isn't synchronous so we should 514 * be careful to access it. 515 */ 516 handle = READ_ONCE(page_owner->handle); 517 if (!handle) 518 continue; 519 520 /* Record the next PFN to read in the file offset */ 521 *ppos = (pfn - min_low_pfn) + 1; 522 523 return print_page_owner(buf, count, pfn, page, 524 page_owner, handle); 525 } 526 527 return 0; 528 } 529 530 static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone) 531 { 532 unsigned long pfn = zone->zone_start_pfn; 533 unsigned long end_pfn = zone_end_pfn(zone); 534 unsigned long count = 0; 535 536 /* 537 * Walk the zone in pageblock_nr_pages steps. If a page block spans 538 * a zone boundary, it will be double counted between zones. This does 539 * not matter as the mixed block count will still be correct 540 */ 541 for (; pfn < end_pfn; ) { 542 unsigned long block_end_pfn; 543 544 if (!pfn_valid(pfn)) { 545 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES); 546 continue; 547 } 548 549 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages); 550 block_end_pfn = min(block_end_pfn, end_pfn); 551 552 for (; pfn < block_end_pfn; pfn++) { 553 struct page *page; 554 struct page_ext *page_ext; 555 556 if (!pfn_valid_within(pfn)) 557 continue; 558 559 page = pfn_to_page(pfn); 560 561 if (page_zone(page) != zone) 562 continue; 563 564 /* 565 * To avoid having to grab zone->lock, be a little 566 * careful when reading buddy page order. The only 567 * danger is that we skip too much and potentially miss 568 * some early allocated pages, which is better than 569 * heavy lock contention. 570 */ 571 if (PageBuddy(page)) { 572 unsigned long order = page_order_unsafe(page); 573 574 if (order > 0 && order < MAX_ORDER) 575 pfn += (1UL << order) - 1; 576 continue; 577 } 578 579 if (PageReserved(page)) 580 continue; 581 582 page_ext = lookup_page_ext(page); 583 if (unlikely(!page_ext)) 584 continue; 585 586 /* Maybe overlapping zone */ 587 if (test_bit(PAGE_EXT_OWNER, &page_ext->flags)) 588 continue; 589 590 /* Found early allocated page */ 591 __set_page_owner_handle(page_ext, early_handle, 0, 0); 592 count++; 593 } 594 cond_resched(); 595 } 596 597 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n", 598 pgdat->node_id, zone->name, count); 599 } 600 601 static void init_zones_in_node(pg_data_t *pgdat) 602 { 603 struct zone *zone; 604 struct zone *node_zones = pgdat->node_zones; 605 606 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { 607 if (!populated_zone(zone)) 608 continue; 609 610 init_pages_in_zone(pgdat, zone); 611 } 612 } 613 614 static void init_early_allocated_pages(void) 615 { 616 pg_data_t *pgdat; 617 618 for_each_online_pgdat(pgdat) 619 init_zones_in_node(pgdat); 620 } 621 622 static const struct file_operations proc_page_owner_operations = { 623 .read = read_page_owner, 624 }; 625 626 static int __init pageowner_init(void) 627 { 628 if (!static_branch_unlikely(&page_owner_inited)) { 629 pr_info("page_owner is disabled\n"); 630 return 0; 631 } 632 633 debugfs_create_file("page_owner", 0400, NULL, NULL, 634 &proc_page_owner_operations); 635 636 return 0; 637 } 638 late_initcall(pageowner_init) 639