mm/page_owner.c

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