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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
24struct 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
39static bool page_owner_enabled __initdata;
40DEFINE_STATIC_KEY_FALSE(page_owner_inited);
41
42static depot_stack_handle_t dummy_handle;
43static depot_stack_handle_t failure_handle;
44static depot_stack_handle_t early_handle;
45
46static void init_early_allocated_pages(void);
47
48static int __init early_page_owner_param(char *buf)
49{
50 int ret = kstrtobool(buf, &page_owner_enabled);
51
52 if (page_owner_enabled)
53 stack_depot_request_early_init();
54
55 return ret;
56}
57early_param("page_owner", early_page_owner_param);
58
59static __init bool need_page_owner(void)
60{
61 return page_owner_enabled;
62}
63
64static __always_inline depot_stack_handle_t create_dummy_stack(void)
65{
66 unsigned long entries[4];
67 unsigned int nr_entries;
68
69 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
70 return stack_depot_save(entries, nr_entries, GFP_KERNEL);
71}
72
73static noinline void register_dummy_stack(void)
74{
75 dummy_handle = create_dummy_stack();
76}
77
78static noinline void register_failure_stack(void)
79{
80 failure_handle = create_dummy_stack();
81}
82
83static noinline void register_early_stack(void)
84{
85 early_handle = create_dummy_stack();
86}
87
88static __init void init_page_owner(void)
89{
90 if (!page_owner_enabled)
91 return;
92
93 register_dummy_stack();
94 register_failure_stack();
95 register_early_stack();
96 static_branch_enable(&page_owner_inited);
97 init_early_allocated_pages();
98}
99
100struct page_ext_operations page_owner_ops = {
101 .size = sizeof(struct page_owner),
102 .need = need_page_owner,
103 .init = init_page_owner,
104 .need_shared_flags = true,
105};
106
107static inline struct page_owner *get_page_owner(struct page_ext *page_ext)
108{
109 return page_ext_data(page_ext, &page_owner_ops);
110}
111
112static noinline depot_stack_handle_t save_stack(gfp_t flags)
113{
114 unsigned long entries[PAGE_OWNER_STACK_DEPTH];
115 depot_stack_handle_t handle;
116 unsigned int nr_entries;
117
118 /*
119 * Avoid recursion.
120 *
121 * Sometimes page metadata allocation tracking requires more
122 * memory to be allocated:
123 * - when new stack trace is saved to stack depot
124 */
125 if (current->in_page_owner)
126 return dummy_handle;
127 current->in_page_owner = 1;
128
129 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2);
130 handle = stack_depot_save(entries, nr_entries, flags);
131 if (!handle)
132 handle = failure_handle;
133
134 current->in_page_owner = 0;
135 return handle;
136}
137
138void __reset_page_owner(struct page *page, unsigned short order)
139{
140 int i;
141 struct page_ext *page_ext;
142 depot_stack_handle_t handle;
143 struct page_owner *page_owner;
144 u64 free_ts_nsec = local_clock();
145
146 page_ext = page_ext_get(page);
147 if (unlikely(!page_ext))
148 return;
149
150 handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
151 for (i = 0; i < (1 << order); i++) {
152 __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
153 page_owner = get_page_owner(page_ext);
154 page_owner->free_handle = handle;
155 page_owner->free_ts_nsec = free_ts_nsec;
156 page_owner->free_pid = current->pid;
157 page_owner->free_tgid = current->tgid;
158 page_ext = page_ext_next(page_ext);
159 }
160 page_ext_put(page_ext);
161}
162
163static inline void __set_page_owner_handle(struct page_ext *page_ext,
164 depot_stack_handle_t handle,
165 unsigned short order, gfp_t gfp_mask)
166{
167 struct page_owner *page_owner;
168 int i;
169 u64 ts_nsec = local_clock();
170
171 for (i = 0; i < (1 << order); i++) {
172 page_owner = get_page_owner(page_ext);
173 page_owner->handle = handle;
174 page_owner->order = order;
175 page_owner->gfp_mask = gfp_mask;
176 page_owner->last_migrate_reason = -1;
177 page_owner->pid = current->pid;
178 page_owner->tgid = current->tgid;
179 page_owner->ts_nsec = ts_nsec;
180 strscpy(page_owner->comm, current->comm,
181 sizeof(page_owner->comm));
182 __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
183 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
184
185 page_ext = page_ext_next(page_ext);
186 }
187}
188
189noinline void __set_page_owner(struct page *page, unsigned short order,
190 gfp_t gfp_mask)
191{
192 struct page_ext *page_ext;
193 depot_stack_handle_t handle;
194
195 handle = save_stack(gfp_mask);
196
197 page_ext = page_ext_get(page);
198 if (unlikely(!page_ext))
199 return;
200 __set_page_owner_handle(page_ext, handle, order, gfp_mask);
201 page_ext_put(page_ext);
202}
203
204void __set_page_owner_migrate_reason(struct page *page, int reason)
205{
206 struct page_ext *page_ext = page_ext_get(page);
207 struct page_owner *page_owner;
208
209 if (unlikely(!page_ext))
210 return;
211
212 page_owner = get_page_owner(page_ext);
213 page_owner->last_migrate_reason = reason;
214 page_ext_put(page_ext);
215}
216
217void __split_page_owner(struct page *page, unsigned int nr)
218{
219 int i;
220 struct page_ext *page_ext = page_ext_get(page);
221 struct page_owner *page_owner;
222
223 if (unlikely(!page_ext))
224 return;
225
226 for (i = 0; i < nr; i++) {
227 page_owner = get_page_owner(page_ext);
228 page_owner->order = 0;
229 page_ext = page_ext_next(page_ext);
230 }
231 page_ext_put(page_ext);
232}
233
234void __folio_copy_owner(struct folio *newfolio, struct folio *old)
235{
236 struct page_ext *old_ext;
237 struct page_ext *new_ext;
238 struct page_owner *old_page_owner, *new_page_owner;
239
240 old_ext = page_ext_get(&old->page);
241 if (unlikely(!old_ext))
242 return;
243
244 new_ext = page_ext_get(&newfolio->page);
245 if (unlikely(!new_ext)) {
246 page_ext_put(old_ext);
247 return;
248 }
249
250 old_page_owner = get_page_owner(old_ext);
251 new_page_owner = get_page_owner(new_ext);
252 new_page_owner->order = old_page_owner->order;
253 new_page_owner->gfp_mask = old_page_owner->gfp_mask;
254 new_page_owner->last_migrate_reason =
255 old_page_owner->last_migrate_reason;
256 new_page_owner->handle = old_page_owner->handle;
257 new_page_owner->pid = old_page_owner->pid;
258 new_page_owner->tgid = old_page_owner->tgid;
259 new_page_owner->free_pid = old_page_owner->free_pid;
260 new_page_owner->free_tgid = old_page_owner->free_tgid;
261 new_page_owner->ts_nsec = old_page_owner->ts_nsec;
262 new_page_owner->free_ts_nsec = old_page_owner->ts_nsec;
263 strcpy(new_page_owner->comm, old_page_owner->comm);
264
265 /*
266 * We don't clear the bit on the old folio as it's going to be freed
267 * after migration. Until then, the info can be useful in case of
268 * a bug, and the overall stats will be off a bit only temporarily.
269 * Also, migrate_misplaced_transhuge_page() can still fail the
270 * migration and then we want the old folio to retain the info. But
271 * in that case we also don't need to explicitly clear the info from
272 * the new page, which will be freed.
273 */
274 __set_bit(PAGE_EXT_OWNER, &new_ext->flags);
275 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &new_ext->flags);
276 page_ext_put(new_ext);
277 page_ext_put(old_ext);
278}
279
280void pagetypeinfo_showmixedcount_print(struct seq_file *m,
281 pg_data_t *pgdat, struct zone *zone)
282{
283 struct page *page;
284 struct page_ext *page_ext;
285 struct page_owner *page_owner;
286 unsigned long pfn, block_end_pfn;
287 unsigned long end_pfn = zone_end_pfn(zone);
288 unsigned long count[MIGRATE_TYPES] = { 0, };
289 int pageblock_mt, page_mt;
290 int i;
291
292 /* Scan block by block. First and last block may be incomplete */
293 pfn = zone->zone_start_pfn;
294
295 /*
296 * Walk the zone in pageblock_nr_pages steps. If a page block spans
297 * a zone boundary, it will be double counted between zones. This does
298 * not matter as the mixed block count will still be correct
299 */
300 for (; pfn < end_pfn; ) {
301 page = pfn_to_online_page(pfn);
302 if (!page) {
303 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
304 continue;
305 }
306
307 block_end_pfn = pageblock_end_pfn(pfn);
308 block_end_pfn = min(block_end_pfn, end_pfn);
309
310 pageblock_mt = get_pageblock_migratetype(page);
311
312 for (; pfn < block_end_pfn; pfn++) {
313 /* The pageblock is online, no need to recheck. */
314 page = pfn_to_page(pfn);
315
316 if (page_zone(page) != zone)
317 continue;
318
319 if (PageBuddy(page)) {
320 unsigned long freepage_order;
321
322 freepage_order = buddy_order_unsafe(page);
323 if (freepage_order <= MAX_PAGE_ORDER)
324 pfn += (1UL << freepage_order) - 1;
325 continue;
326 }
327
328 if (PageReserved(page))
329 continue;
330
331 page_ext = page_ext_get(page);
332 if (unlikely(!page_ext))
333 continue;
334
335 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
336 goto ext_put_continue;
337
338 page_owner = get_page_owner(page_ext);
339 page_mt = gfp_migratetype(page_owner->gfp_mask);
340 if (pageblock_mt != page_mt) {
341 if (is_migrate_cma(pageblock_mt))
342 count[MIGRATE_MOVABLE]++;
343 else
344 count[pageblock_mt]++;
345
346 pfn = block_end_pfn;
347 page_ext_put(page_ext);
348 break;
349 }
350 pfn += (1UL << page_owner->order) - 1;
351ext_put_continue:
352 page_ext_put(page_ext);
353 }
354 }
355
356 /* Print counts */
357 seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
358 for (i = 0; i < MIGRATE_TYPES; i++)
359 seq_printf(m, "%12lu ", count[i]);
360 seq_putc(m, '\n');
361}
362
363/*
364 * Looking for memcg information and print it out
365 */
366static inline int print_page_owner_memcg(char *kbuf, size_t count, int ret,
367 struct page *page)
368{
369#ifdef CONFIG_MEMCG
370 unsigned long memcg_data;
371 struct mem_cgroup *memcg;
372 bool online;
373 char name[80];
374
375 rcu_read_lock();
376 memcg_data = READ_ONCE(page->memcg_data);
377 if (!memcg_data)
378 goto out_unlock;
379
380 if (memcg_data & MEMCG_DATA_OBJCGS)
381 ret += scnprintf(kbuf + ret, count - ret,
382 "Slab cache page\n");
383
384 memcg = page_memcg_check(page);
385 if (!memcg)
386 goto out_unlock;
387
388 online = (memcg->css.flags & CSS_ONLINE);
389 cgroup_name(memcg->css.cgroup, name, sizeof(name));
390 ret += scnprintf(kbuf + ret, count - ret,
391 "Charged %sto %smemcg %s\n",
392 PageMemcgKmem(page) ? "(via objcg) " : "",
393 online ? "" : "offline ",
394 name);
395out_unlock:
396 rcu_read_unlock();
397#endif /* CONFIG_MEMCG */
398
399 return ret;
400}
401
402static ssize_t
403print_page_owner(char __user *buf, size_t count, unsigned long pfn,
404 struct page *page, struct page_owner *page_owner,
405 depot_stack_handle_t handle)
406{
407 int ret, pageblock_mt, page_mt;
408 char *kbuf;
409
410 count = min_t(size_t, count, PAGE_SIZE);
411 kbuf = kmalloc(count, GFP_KERNEL);
412 if (!kbuf)
413 return -ENOMEM;
414
415 ret = scnprintf(kbuf, count,
416 "Page allocated via order %u, mask %#x(%pGg), pid %d, tgid %d (%s), ts %llu ns\n",
417 page_owner->order, page_owner->gfp_mask,
418 &page_owner->gfp_mask, page_owner->pid,
419 page_owner->tgid, page_owner->comm,
420 page_owner->ts_nsec);
421
422 /* Print information relevant to grouping pages by mobility */
423 pageblock_mt = get_pageblock_migratetype(page);
424 page_mt = gfp_migratetype(page_owner->gfp_mask);
425 ret += scnprintf(kbuf + ret, count - ret,
426 "PFN 0x%lx type %s Block %lu type %s Flags %pGp\n",
427 pfn,
428 migratetype_names[page_mt],
429 pfn >> pageblock_order,
430 migratetype_names[pageblock_mt],
431 &page->flags);
432
433 ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0);
434 if (ret >= count)
435 goto err;
436
437 if (page_owner->last_migrate_reason != -1) {
438 ret += scnprintf(kbuf + ret, count - ret,
439 "Page has been migrated, last migrate reason: %s\n",
440 migrate_reason_names[page_owner->last_migrate_reason]);
441 }
442
443 ret = print_page_owner_memcg(kbuf, count, ret, page);
444
445 ret += snprintf(kbuf + ret, count - ret, "\n");
446 if (ret >= count)
447 goto err;
448
449 if (copy_to_user(buf, kbuf, ret))
450 ret = -EFAULT;
451
452 kfree(kbuf);
453 return ret;
454
455err:
456 kfree(kbuf);
457 return -ENOMEM;
458}
459
460void __dump_page_owner(const struct page *page)
461{
462 struct page_ext *page_ext = page_ext_get((void *)page);
463 struct page_owner *page_owner;
464 depot_stack_handle_t handle;
465 gfp_t gfp_mask;
466 int mt;
467
468 if (unlikely(!page_ext)) {
469 pr_alert("There is not page extension available.\n");
470 return;
471 }
472
473 page_owner = get_page_owner(page_ext);
474 gfp_mask = page_owner->gfp_mask;
475 mt = gfp_migratetype(gfp_mask);
476
477 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
478 pr_alert("page_owner info is not present (never set?)\n");
479 page_ext_put(page_ext);
480 return;
481 }
482
483 if (test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
484 pr_alert("page_owner tracks the page as allocated\n");
485 else
486 pr_alert("page_owner tracks the page as freed\n");
487
488 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",
489 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask,
490 page_owner->pid, page_owner->tgid, page_owner->comm,
491 page_owner->ts_nsec, page_owner->free_ts_nsec);
492
493 handle = READ_ONCE(page_owner->handle);
494 if (!handle)
495 pr_alert("page_owner allocation stack trace missing\n");
496 else
497 stack_depot_print(handle);
498
499 handle = READ_ONCE(page_owner->free_handle);
500 if (!handle) {
501 pr_alert("page_owner free stack trace missing\n");
502 } else {
503 pr_alert("page last free pid %d tgid %d stack trace:\n",
504 page_owner->free_pid, page_owner->free_tgid);
505 stack_depot_print(handle);
506 }
507
508 if (page_owner->last_migrate_reason != -1)
509 pr_alert("page has been migrated, last migrate reason: %s\n",
510 migrate_reason_names[page_owner->last_migrate_reason]);
511 page_ext_put(page_ext);
512}
513
514static ssize_t
515read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
516{
517 unsigned long pfn;
518 struct page *page;
519 struct page_ext *page_ext;
520 struct page_owner *page_owner;
521 depot_stack_handle_t handle;
522
523 if (!static_branch_unlikely(&page_owner_inited))
524 return -EINVAL;
525
526 page = NULL;
527 if (*ppos == 0)
528 pfn = min_low_pfn;
529 else
530 pfn = *ppos;
531 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
532 while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
533 pfn++;
534
535 /* Find an allocated page */
536 for (; pfn < max_pfn; pfn++) {
537 /*
538 * This temporary page_owner is required so
539 * that we can avoid the context switches while holding
540 * the rcu lock and copying the page owner information to
541 * user through copy_to_user() or GFP_KERNEL allocations.
542 */
543 struct page_owner page_owner_tmp;
544
545 /*
546 * If the new page is in a new MAX_ORDER_NR_PAGES area,
547 * validate the area as existing, skip it if not
548 */
549 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
550 pfn += MAX_ORDER_NR_PAGES - 1;
551 continue;
552 }
553
554 page = pfn_to_page(pfn);
555 if (PageBuddy(page)) {
556 unsigned long freepage_order = buddy_order_unsafe(page);
557
558 if (freepage_order <= MAX_PAGE_ORDER)
559 pfn += (1UL << freepage_order) - 1;
560 continue;
561 }
562
563 page_ext = page_ext_get(page);
564 if (unlikely(!page_ext))
565 continue;
566
567 /*
568 * Some pages could be missed by concurrent allocation or free,
569 * because we don't hold the zone lock.
570 */
571 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
572 goto ext_put_continue;
573
574 /*
575 * Although we do have the info about past allocation of free
576 * pages, it's not relevant for current memory usage.
577 */
578 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
579 goto ext_put_continue;
580
581 page_owner = get_page_owner(page_ext);
582
583 /*
584 * Don't print "tail" pages of high-order allocations as that
585 * would inflate the stats.
586 */
587 if (!IS_ALIGNED(pfn, 1 << page_owner->order))
588 goto ext_put_continue;
589
590 /*
591 * Access to page_ext->handle isn't synchronous so we should
592 * be careful to access it.
593 */
594 handle = READ_ONCE(page_owner->handle);
595 if (!handle)
596 goto ext_put_continue;
597
598 /* Record the next PFN to read in the file offset */
599 *ppos = pfn + 1;
600
601 page_owner_tmp = *page_owner;
602 page_ext_put(page_ext);
603 return print_page_owner(buf, count, pfn, page,
604 &page_owner_tmp, handle);
605ext_put_continue:
606 page_ext_put(page_ext);
607 }
608
609 return 0;
610}
611
612static loff_t lseek_page_owner(struct file *file, loff_t offset, int orig)
613{
614 switch (orig) {
615 case SEEK_SET:
616 file->f_pos = offset;
617 break;
618 case SEEK_CUR:
619 file->f_pos += offset;
620 break;
621 default:
622 return -EINVAL;
623 }
624 return file->f_pos;
625}
626
627static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
628{
629 unsigned long pfn = zone->zone_start_pfn;
630 unsigned long end_pfn = zone_end_pfn(zone);
631 unsigned long count = 0;
632
633 /*
634 * Walk the zone in pageblock_nr_pages steps. If a page block spans
635 * a zone boundary, it will be double counted between zones. This does
636 * not matter as the mixed block count will still be correct
637 */
638 for (; pfn < end_pfn; ) {
639 unsigned long block_end_pfn;
640
641 if (!pfn_valid(pfn)) {
642 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
643 continue;
644 }
645
646 block_end_pfn = pageblock_end_pfn(pfn);
647 block_end_pfn = min(block_end_pfn, end_pfn);
648
649 for (; pfn < block_end_pfn; pfn++) {
650 struct page *page = pfn_to_page(pfn);
651 struct page_ext *page_ext;
652
653 if (page_zone(page) != zone)
654 continue;
655
656 /*
657 * To avoid having to grab zone->lock, be a little
658 * careful when reading buddy page order. The only
659 * danger is that we skip too much and potentially miss
660 * some early allocated pages, which is better than
661 * heavy lock contention.
662 */
663 if (PageBuddy(page)) {
664 unsigned long order = buddy_order_unsafe(page);
665
666 if (order > 0 && order <= MAX_PAGE_ORDER)
667 pfn += (1UL << order) - 1;
668 continue;
669 }
670
671 if (PageReserved(page))
672 continue;
673
674 page_ext = page_ext_get(page);
675 if (unlikely(!page_ext))
676 continue;
677
678 /* Maybe overlapping zone */
679 if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
680 goto ext_put_continue;
681
682 /* Found early allocated page */
683 __set_page_owner_handle(page_ext, early_handle,
684 0, 0);
685 count++;
686ext_put_continue:
687 page_ext_put(page_ext);
688 }
689 cond_resched();
690 }
691
692 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
693 pgdat->node_id, zone->name, count);
694}
695
696static void init_zones_in_node(pg_data_t *pgdat)
697{
698 struct zone *zone;
699 struct zone *node_zones = pgdat->node_zones;
700
701 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
702 if (!populated_zone(zone))
703 continue;
704
705 init_pages_in_zone(pgdat, zone);
706 }
707}
708
709static void init_early_allocated_pages(void)
710{
711 pg_data_t *pgdat;
712
713 for_each_online_pgdat(pgdat)
714 init_zones_in_node(pgdat);
715}
716
717static const struct file_operations proc_page_owner_operations = {
718 .read = read_page_owner,
719 .llseek = lseek_page_owner,
720};
721
722static int __init pageowner_init(void)
723{
724 if (!static_branch_unlikely(&page_owner_inited)) {
725 pr_info("page_owner is disabled\n");
726 return 0;
727 }
728
729 debugfs_create_file("page_owner", 0400, NULL, NULL,
730 &proc_page_owner_operations);
731
732 return 0;
733}
734late_initcall(pageowner_init)