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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};
36
37static bool page_owner_enabled __initdata;
38DEFINE_STATIC_KEY_FALSE(page_owner_inited);
39
40static depot_stack_handle_t dummy_handle;
41static depot_stack_handle_t failure_handle;
42static depot_stack_handle_t early_handle;
43
44static void init_early_allocated_pages(void);
45
46static int __init early_page_owner_param(char *buf)
47{
48 int ret = kstrtobool(buf, &page_owner_enabled);
49
50 if (page_owner_enabled)
51 stack_depot_want_early_init();
52
53 return ret;
54}
55early_param("page_owner", early_page_owner_param);
56
57static __init bool need_page_owner(void)
58{
59 return page_owner_enabled;
60}
61
62static __always_inline depot_stack_handle_t create_dummy_stack(void)
63{
64 unsigned long entries[4];
65 unsigned int nr_entries;
66
67 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
68 return stack_depot_save(entries, nr_entries, GFP_KERNEL);
69}
70
71static noinline void register_dummy_stack(void)
72{
73 dummy_handle = create_dummy_stack();
74}
75
76static noinline void register_failure_stack(void)
77{
78 failure_handle = create_dummy_stack();
79}
80
81static noinline void register_early_stack(void)
82{
83 early_handle = create_dummy_stack();
84}
85
86static __init void init_page_owner(void)
87{
88 if (!page_owner_enabled)
89 return;
90
91 register_dummy_stack();
92 register_failure_stack();
93 register_early_stack();
94 static_branch_enable(&page_owner_inited);
95 init_early_allocated_pages();
96}
97
98struct page_ext_operations page_owner_ops = {
99 .size = sizeof(struct page_owner),
100 .need = need_page_owner,
101 .init = init_page_owner,
102};
103
104static inline struct page_owner *get_page_owner(struct page_ext *page_ext)
105{
106 return (void *)page_ext + page_owner_ops.offset;
107}
108
109static noinline depot_stack_handle_t save_stack(gfp_t flags)
110{
111 unsigned long entries[PAGE_OWNER_STACK_DEPTH];
112 depot_stack_handle_t handle;
113 unsigned int nr_entries;
114
115 /*
116 * Avoid recursion.
117 *
118 * Sometimes page metadata allocation tracking requires more
119 * memory to be allocated:
120 * - when new stack trace is saved to stack depot
121 * - when backtrace itself is calculated (ia64)
122 */
123 if (current->in_page_owner)
124 return dummy_handle;
125 current->in_page_owner = 1;
126
127 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2);
128 handle = stack_depot_save(entries, nr_entries, flags);
129 if (!handle)
130 handle = failure_handle;
131
132 current->in_page_owner = 0;
133 return handle;
134}
135
136void __reset_page_owner(struct page *page, unsigned short order)
137{
138 int i;
139 struct page_ext *page_ext;
140 depot_stack_handle_t handle;
141 struct page_owner *page_owner;
142 u64 free_ts_nsec = local_clock();
143
144 page_ext = page_ext_get(page);
145 if (unlikely(!page_ext))
146 return;
147
148 handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
149 for (i = 0; i < (1 << order); i++) {
150 __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
151 page_owner = get_page_owner(page_ext);
152 page_owner->free_handle = handle;
153 page_owner->free_ts_nsec = free_ts_nsec;
154 page_ext = page_ext_next(page_ext);
155 }
156 page_ext_put(page_ext);
157}
158
159static inline void __set_page_owner_handle(struct page_ext *page_ext,
160 depot_stack_handle_t handle,
161 unsigned short order, gfp_t gfp_mask)
162{
163 struct page_owner *page_owner;
164 int i;
165
166 for (i = 0; i < (1 << order); i++) {
167 page_owner = get_page_owner(page_ext);
168 page_owner->handle = handle;
169 page_owner->order = order;
170 page_owner->gfp_mask = gfp_mask;
171 page_owner->last_migrate_reason = -1;
172 page_owner->pid = current->pid;
173 page_owner->tgid = current->tgid;
174 page_owner->ts_nsec = local_clock();
175 strscpy(page_owner->comm, current->comm,
176 sizeof(page_owner->comm));
177 __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
178 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
179
180 page_ext = page_ext_next(page_ext);
181 }
182}
183
184noinline void __set_page_owner(struct page *page, unsigned short order,
185 gfp_t gfp_mask)
186{
187 struct page_ext *page_ext;
188 depot_stack_handle_t handle;
189
190 handle = save_stack(gfp_mask);
191
192 page_ext = page_ext_get(page);
193 if (unlikely(!page_ext))
194 return;
195 __set_page_owner_handle(page_ext, handle, order, gfp_mask);
196 page_ext_put(page_ext);
197}
198
199void __set_page_owner_migrate_reason(struct page *page, int reason)
200{
201 struct page_ext *page_ext = page_ext_get(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 page_ext_put(page_ext);
210}
211
212void __split_page_owner(struct page *page, unsigned int nr)
213{
214 int i;
215 struct page_ext *page_ext = page_ext_get(page);
216 struct page_owner *page_owner;
217
218 if (unlikely(!page_ext))
219 return;
220
221 for (i = 0; i < nr; i++) {
222 page_owner = get_page_owner(page_ext);
223 page_owner->order = 0;
224 page_ext = page_ext_next(page_ext);
225 }
226 page_ext_put(page_ext);
227}
228
229void __folio_copy_owner(struct folio *newfolio, struct folio *old)
230{
231 struct page_ext *old_ext;
232 struct page_ext *new_ext;
233 struct page_owner *old_page_owner, *new_page_owner;
234
235 old_ext = page_ext_get(&old->page);
236 if (unlikely(!old_ext))
237 return;
238
239 new_ext = page_ext_get(&newfolio->page);
240 if (unlikely(!new_ext)) {
241 page_ext_put(old_ext);
242 return;
243 }
244
245 old_page_owner = get_page_owner(old_ext);
246 new_page_owner = get_page_owner(new_ext);
247 new_page_owner->order = old_page_owner->order;
248 new_page_owner->gfp_mask = old_page_owner->gfp_mask;
249 new_page_owner->last_migrate_reason =
250 old_page_owner->last_migrate_reason;
251 new_page_owner->handle = old_page_owner->handle;
252 new_page_owner->pid = old_page_owner->pid;
253 new_page_owner->tgid = old_page_owner->tgid;
254 new_page_owner->ts_nsec = old_page_owner->ts_nsec;
255 new_page_owner->free_ts_nsec = old_page_owner->ts_nsec;
256 strcpy(new_page_owner->comm, old_page_owner->comm);
257
258 /*
259 * We don't clear the bit on the old folio as it's going to be freed
260 * after migration. Until then, the info can be useful in case of
261 * a bug, and the overall stats will be off a bit only temporarily.
262 * Also, migrate_misplaced_transhuge_page() can still fail the
263 * migration and then we want the old folio to retain the info. But
264 * in that case we also don't need to explicitly clear the info from
265 * the new page, which will be freed.
266 */
267 __set_bit(PAGE_EXT_OWNER, &new_ext->flags);
268 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &new_ext->flags);
269 page_ext_put(new_ext);
270 page_ext_put(old_ext);
271}
272
273void pagetypeinfo_showmixedcount_print(struct seq_file *m,
274 pg_data_t *pgdat, struct zone *zone)
275{
276 struct page *page;
277 struct page_ext *page_ext;
278 struct page_owner *page_owner;
279 unsigned long pfn, block_end_pfn;
280 unsigned long end_pfn = zone_end_pfn(zone);
281 unsigned long count[MIGRATE_TYPES] = { 0, };
282 int pageblock_mt, page_mt;
283 int i;
284
285 /* Scan block by block. First and last block may be incomplete */
286 pfn = zone->zone_start_pfn;
287
288 /*
289 * Walk the zone in pageblock_nr_pages steps. If a page block spans
290 * a zone boundary, it will be double counted between zones. This does
291 * not matter as the mixed block count will still be correct
292 */
293 for (; pfn < end_pfn; ) {
294 page = pfn_to_online_page(pfn);
295 if (!page) {
296 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
297 continue;
298 }
299
300 block_end_pfn = pageblock_end_pfn(pfn);
301 block_end_pfn = min(block_end_pfn, end_pfn);
302
303 pageblock_mt = get_pageblock_migratetype(page);
304
305 for (; pfn < block_end_pfn; pfn++) {
306 /* The pageblock is online, no need to recheck. */
307 page = pfn_to_page(pfn);
308
309 if (page_zone(page) != zone)
310 continue;
311
312 if (PageBuddy(page)) {
313 unsigned long freepage_order;
314
315 freepage_order = buddy_order_unsafe(page);
316 if (freepage_order < MAX_ORDER)
317 pfn += (1UL << freepage_order) - 1;
318 continue;
319 }
320
321 if (PageReserved(page))
322 continue;
323
324 page_ext = page_ext_get(page);
325 if (unlikely(!page_ext))
326 continue;
327
328 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
329 goto ext_put_continue;
330
331 page_owner = get_page_owner(page_ext);
332 page_mt = gfp_migratetype(page_owner->gfp_mask);
333 if (pageblock_mt != page_mt) {
334 if (is_migrate_cma(pageblock_mt))
335 count[MIGRATE_MOVABLE]++;
336 else
337 count[pageblock_mt]++;
338
339 pfn = block_end_pfn;
340 page_ext_put(page_ext);
341 break;
342 }
343 pfn += (1UL << page_owner->order) - 1;
344ext_put_continue:
345 page_ext_put(page_ext);
346 }
347 }
348
349 /* Print counts */
350 seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
351 for (i = 0; i < MIGRATE_TYPES; i++)
352 seq_printf(m, "%12lu ", count[i]);
353 seq_putc(m, '\n');
354}
355
356/*
357 * Looking for memcg information and print it out
358 */
359static inline int print_page_owner_memcg(char *kbuf, size_t count, int ret,
360 struct page *page)
361{
362#ifdef CONFIG_MEMCG
363 unsigned long memcg_data;
364 struct mem_cgroup *memcg;
365 bool online;
366 char name[80];
367
368 rcu_read_lock();
369 memcg_data = READ_ONCE(page->memcg_data);
370 if (!memcg_data)
371 goto out_unlock;
372
373 if (memcg_data & MEMCG_DATA_OBJCGS)
374 ret += scnprintf(kbuf + ret, count - ret,
375 "Slab cache page\n");
376
377 memcg = page_memcg_check(page);
378 if (!memcg)
379 goto out_unlock;
380
381 online = (memcg->css.flags & CSS_ONLINE);
382 cgroup_name(memcg->css.cgroup, name, sizeof(name));
383 ret += scnprintf(kbuf + ret, count - ret,
384 "Charged %sto %smemcg %s\n",
385 PageMemcgKmem(page) ? "(via objcg) " : "",
386 online ? "" : "offline ",
387 name);
388out_unlock:
389 rcu_read_unlock();
390#endif /* CONFIG_MEMCG */
391
392 return ret;
393}
394
395static ssize_t
396print_page_owner(char __user *buf, size_t count, unsigned long pfn,
397 struct page *page, struct page_owner *page_owner,
398 depot_stack_handle_t handle)
399{
400 int ret, pageblock_mt, page_mt;
401 char *kbuf;
402
403 count = min_t(size_t, count, PAGE_SIZE);
404 kbuf = kmalloc(count, GFP_KERNEL);
405 if (!kbuf)
406 return -ENOMEM;
407
408 ret = scnprintf(kbuf, count,
409 "Page allocated via order %u, mask %#x(%pGg), pid %d, tgid %d (%s), ts %llu ns, free_ts %llu ns\n",
410 page_owner->order, page_owner->gfp_mask,
411 &page_owner->gfp_mask, page_owner->pid,
412 page_owner->tgid, page_owner->comm,
413 page_owner->ts_nsec, page_owner->free_ts_nsec);
414
415 /* Print information relevant to grouping pages by mobility */
416 pageblock_mt = get_pageblock_migratetype(page);
417 page_mt = gfp_migratetype(page_owner->gfp_mask);
418 ret += scnprintf(kbuf + ret, count - ret,
419 "PFN %lu type %s Block %lu type %s Flags %pGp\n",
420 pfn,
421 migratetype_names[page_mt],
422 pfn >> pageblock_order,
423 migratetype_names[pageblock_mt],
424 &page->flags);
425
426 ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0);
427 if (ret >= count)
428 goto err;
429
430 if (page_owner->last_migrate_reason != -1) {
431 ret += scnprintf(kbuf + ret, count - ret,
432 "Page has been migrated, last migrate reason: %s\n",
433 migrate_reason_names[page_owner->last_migrate_reason]);
434 }
435
436 ret = print_page_owner_memcg(kbuf, count, ret, page);
437
438 ret += snprintf(kbuf + ret, count - ret, "\n");
439 if (ret >= count)
440 goto err;
441
442 if (copy_to_user(buf, kbuf, ret))
443 ret = -EFAULT;
444
445 kfree(kbuf);
446 return ret;
447
448err:
449 kfree(kbuf);
450 return -ENOMEM;
451}
452
453void __dump_page_owner(const struct page *page)
454{
455 struct page_ext *page_ext = page_ext_get((void *)page);
456 struct page_owner *page_owner;
457 depot_stack_handle_t handle;
458 gfp_t gfp_mask;
459 int mt;
460
461 if (unlikely(!page_ext)) {
462 pr_alert("There is not page extension available.\n");
463 return;
464 }
465
466 page_owner = get_page_owner(page_ext);
467 gfp_mask = page_owner->gfp_mask;
468 mt = gfp_migratetype(gfp_mask);
469
470 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
471 pr_alert("page_owner info is not present (never set?)\n");
472 page_ext_put(page_ext);
473 return;
474 }
475
476 if (test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
477 pr_alert("page_owner tracks the page as allocated\n");
478 else
479 pr_alert("page_owner tracks the page as freed\n");
480
481 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",
482 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask,
483 page_owner->pid, page_owner->tgid, page_owner->comm,
484 page_owner->ts_nsec, page_owner->free_ts_nsec);
485
486 handle = READ_ONCE(page_owner->handle);
487 if (!handle)
488 pr_alert("page_owner allocation stack trace missing\n");
489 else
490 stack_depot_print(handle);
491
492 handle = READ_ONCE(page_owner->free_handle);
493 if (!handle) {
494 pr_alert("page_owner free stack trace missing\n");
495 } else {
496 pr_alert("page last free stack trace:\n");
497 stack_depot_print(handle);
498 }
499
500 if (page_owner->last_migrate_reason != -1)
501 pr_alert("page has been migrated, last migrate reason: %s\n",
502 migrate_reason_names[page_owner->last_migrate_reason]);
503 page_ext_put(page_ext);
504}
505
506static ssize_t
507read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
508{
509 unsigned long pfn;
510 struct page *page;
511 struct page_ext *page_ext;
512 struct page_owner *page_owner;
513 depot_stack_handle_t handle;
514
515 if (!static_branch_unlikely(&page_owner_inited))
516 return -EINVAL;
517
518 page = NULL;
519 if (*ppos == 0)
520 pfn = min_low_pfn;
521 else
522 pfn = *ppos;
523 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
524 while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
525 pfn++;
526
527 /* Find an allocated page */
528 for (; pfn < max_pfn; pfn++) {
529 /*
530 * This temporary page_owner is required so
531 * that we can avoid the context switches while holding
532 * the rcu lock and copying the page owner information to
533 * user through copy_to_user() or GFP_KERNEL allocations.
534 */
535 struct page_owner page_owner_tmp;
536
537 /*
538 * If the new page is in a new MAX_ORDER_NR_PAGES area,
539 * validate the area as existing, skip it if not
540 */
541 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
542 pfn += MAX_ORDER_NR_PAGES - 1;
543 continue;
544 }
545
546 page = pfn_to_page(pfn);
547 if (PageBuddy(page)) {
548 unsigned long freepage_order = buddy_order_unsafe(page);
549
550 if (freepage_order < MAX_ORDER)
551 pfn += (1UL << freepage_order) - 1;
552 continue;
553 }
554
555 page_ext = page_ext_get(page);
556 if (unlikely(!page_ext))
557 continue;
558
559 /*
560 * Some pages could be missed by concurrent allocation or free,
561 * because we don't hold the zone lock.
562 */
563 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
564 goto ext_put_continue;
565
566 /*
567 * Although we do have the info about past allocation of free
568 * pages, it's not relevant for current memory usage.
569 */
570 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
571 goto ext_put_continue;
572
573 page_owner = get_page_owner(page_ext);
574
575 /*
576 * Don't print "tail" pages of high-order allocations as that
577 * would inflate the stats.
578 */
579 if (!IS_ALIGNED(pfn, 1 << page_owner->order))
580 goto ext_put_continue;
581
582 /*
583 * Access to page_ext->handle isn't synchronous so we should
584 * be careful to access it.
585 */
586 handle = READ_ONCE(page_owner->handle);
587 if (!handle)
588 goto ext_put_continue;
589
590 /* Record the next PFN to read in the file offset */
591 *ppos = pfn + 1;
592
593 page_owner_tmp = *page_owner;
594 page_ext_put(page_ext);
595 return print_page_owner(buf, count, pfn, page,
596 &page_owner_tmp, handle);
597ext_put_continue:
598 page_ext_put(page_ext);
599 }
600
601 return 0;
602}
603
604static loff_t lseek_page_owner(struct file *file, loff_t offset, int orig)
605{
606 switch (orig) {
607 case SEEK_SET:
608 file->f_pos = offset;
609 break;
610 case SEEK_CUR:
611 file->f_pos += offset;
612 break;
613 default:
614 return -EINVAL;
615 }
616 return file->f_pos;
617}
618
619static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
620{
621 unsigned long pfn = zone->zone_start_pfn;
622 unsigned long end_pfn = zone_end_pfn(zone);
623 unsigned long count = 0;
624
625 /*
626 * Walk the zone in pageblock_nr_pages steps. If a page block spans
627 * a zone boundary, it will be double counted between zones. This does
628 * not matter as the mixed block count will still be correct
629 */
630 for (; pfn < end_pfn; ) {
631 unsigned long block_end_pfn;
632
633 if (!pfn_valid(pfn)) {
634 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
635 continue;
636 }
637
638 block_end_pfn = pageblock_end_pfn(pfn);
639 block_end_pfn = min(block_end_pfn, end_pfn);
640
641 for (; pfn < block_end_pfn; pfn++) {
642 struct page *page = pfn_to_page(pfn);
643 struct page_ext *page_ext;
644
645 if (page_zone(page) != zone)
646 continue;
647
648 /*
649 * To avoid having to grab zone->lock, be a little
650 * careful when reading buddy page order. The only
651 * danger is that we skip too much and potentially miss
652 * some early allocated pages, which is better than
653 * heavy lock contention.
654 */
655 if (PageBuddy(page)) {
656 unsigned long order = buddy_order_unsafe(page);
657
658 if (order > 0 && order < MAX_ORDER)
659 pfn += (1UL << order) - 1;
660 continue;
661 }
662
663 if (PageReserved(page))
664 continue;
665
666 page_ext = page_ext_get(page);
667 if (unlikely(!page_ext))
668 continue;
669
670 /* Maybe overlapping zone */
671 if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
672 goto ext_put_continue;
673
674 /* Found early allocated page */
675 __set_page_owner_handle(page_ext, early_handle,
676 0, 0);
677 count++;
678ext_put_continue:
679 page_ext_put(page_ext);
680 }
681 cond_resched();
682 }
683
684 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
685 pgdat->node_id, zone->name, count);
686}
687
688static void init_zones_in_node(pg_data_t *pgdat)
689{
690 struct zone *zone;
691 struct zone *node_zones = pgdat->node_zones;
692
693 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
694 if (!populated_zone(zone))
695 continue;
696
697 init_pages_in_zone(pgdat, zone);
698 }
699}
700
701static void init_early_allocated_pages(void)
702{
703 pg_data_t *pgdat;
704
705 for_each_online_pgdat(pgdat)
706 init_zones_in_node(pgdat);
707}
708
709static const struct file_operations proc_page_owner_operations = {
710 .read = read_page_owner,
711 .llseek = lseek_page_owner,
712};
713
714static int __init pageowner_init(void)
715{
716 if (!static_branch_unlikely(&page_owner_inited)) {
717 pr_info("page_owner is disabled\n");
718 return 0;
719 }
720
721 debugfs_create_file("page_owner", 0400, NULL, NULL,
722 &proc_page_owner_operations);
723
724 return 0;
725}
726late_initcall(pageowner_init)