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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/sched/clock.h>
14
15#include "internal.h"
16
17/*
18 * TODO: teach PAGE_OWNER_STACK_DEPTH (__dump_page_owner and save_stack)
19 * to use off stack temporal storage
20 */
21#define PAGE_OWNER_STACK_DEPTH (16)
22
23struct page_owner {
24 unsigned short order;
25 short last_migrate_reason;
26 gfp_t gfp_mask;
27 depot_stack_handle_t handle;
28 depot_stack_handle_t free_handle;
29 u64 ts_nsec;
30 u64 free_ts_nsec;
31 pid_t pid;
32};
33
34static bool page_owner_enabled = false;
35DEFINE_STATIC_KEY_FALSE(page_owner_inited);
36
37static depot_stack_handle_t dummy_handle;
38static depot_stack_handle_t failure_handle;
39static depot_stack_handle_t early_handle;
40
41static void init_early_allocated_pages(void);
42
43static int __init early_page_owner_param(char *buf)
44{
45 return kstrtobool(buf, &page_owner_enabled);
46}
47early_param("page_owner", early_page_owner_param);
48
49static bool need_page_owner(void)
50{
51 return page_owner_enabled;
52}
53
54static __always_inline depot_stack_handle_t create_dummy_stack(void)
55{
56 unsigned long entries[4];
57 unsigned int nr_entries;
58
59 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
60 return stack_depot_save(entries, nr_entries, GFP_KERNEL);
61}
62
63static noinline void register_dummy_stack(void)
64{
65 dummy_handle = create_dummy_stack();
66}
67
68static noinline void register_failure_stack(void)
69{
70 failure_handle = create_dummy_stack();
71}
72
73static noinline void register_early_stack(void)
74{
75 early_handle = create_dummy_stack();
76}
77
78static void init_page_owner(void)
79{
80 if (!page_owner_enabled)
81 return;
82
83 register_dummy_stack();
84 register_failure_stack();
85 register_early_stack();
86 static_branch_enable(&page_owner_inited);
87 init_early_allocated_pages();
88}
89
90struct page_ext_operations page_owner_ops = {
91 .size = sizeof(struct page_owner),
92 .need = need_page_owner,
93 .init = init_page_owner,
94};
95
96static inline struct page_owner *get_page_owner(struct page_ext *page_ext)
97{
98 return (void *)page_ext + page_owner_ops.offset;
99}
100
101static noinline depot_stack_handle_t save_stack(gfp_t flags)
102{
103 unsigned long entries[PAGE_OWNER_STACK_DEPTH];
104 depot_stack_handle_t handle;
105 unsigned int nr_entries;
106
107 /*
108 * Avoid recursion.
109 *
110 * Sometimes page metadata allocation tracking requires more
111 * memory to be allocated:
112 * - when new stack trace is saved to stack depot
113 * - when backtrace itself is calculated (ia64)
114 */
115 if (current->in_page_owner)
116 return dummy_handle;
117 current->in_page_owner = 1;
118
119 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2);
120 handle = stack_depot_save(entries, nr_entries, flags);
121 if (!handle)
122 handle = failure_handle;
123
124 current->in_page_owner = 0;
125 return handle;
126}
127
128void __reset_page_owner(struct page *page, unsigned int order)
129{
130 int i;
131 struct page_ext *page_ext;
132 depot_stack_handle_t handle;
133 struct page_owner *page_owner;
134 u64 free_ts_nsec = local_clock();
135
136 page_ext = lookup_page_ext(page);
137 if (unlikely(!page_ext))
138 return;
139
140 handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
141 for (i = 0; i < (1 << order); i++) {
142 __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
143 page_owner = get_page_owner(page_ext);
144 page_owner->free_handle = handle;
145 page_owner->free_ts_nsec = free_ts_nsec;
146 page_ext = page_ext_next(page_ext);
147 }
148}
149
150static inline void __set_page_owner_handle(struct page_ext *page_ext,
151 depot_stack_handle_t handle,
152 unsigned int order, gfp_t gfp_mask)
153{
154 struct page_owner *page_owner;
155 int i;
156
157 for (i = 0; i < (1 << order); i++) {
158 page_owner = get_page_owner(page_ext);
159 page_owner->handle = handle;
160 page_owner->order = order;
161 page_owner->gfp_mask = gfp_mask;
162 page_owner->last_migrate_reason = -1;
163 page_owner->pid = current->pid;
164 page_owner->ts_nsec = local_clock();
165 __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
166 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
167
168 page_ext = page_ext_next(page_ext);
169 }
170}
171
172noinline void __set_page_owner(struct page *page, unsigned int order,
173 gfp_t gfp_mask)
174{
175 struct page_ext *page_ext = lookup_page_ext(page);
176 depot_stack_handle_t handle;
177
178 if (unlikely(!page_ext))
179 return;
180
181 handle = save_stack(gfp_mask);
182 __set_page_owner_handle(page_ext, handle, order, gfp_mask);
183}
184
185void __set_page_owner_migrate_reason(struct page *page, int reason)
186{
187 struct page_ext *page_ext = lookup_page_ext(page);
188 struct page_owner *page_owner;
189
190 if (unlikely(!page_ext))
191 return;
192
193 page_owner = get_page_owner(page_ext);
194 page_owner->last_migrate_reason = reason;
195}
196
197void __split_page_owner(struct page *page, unsigned int nr)
198{
199 int i;
200 struct page_ext *page_ext = lookup_page_ext(page);
201 struct page_owner *page_owner;
202
203 if (unlikely(!page_ext))
204 return;
205
206 for (i = 0; i < nr; i++) {
207 page_owner = get_page_owner(page_ext);
208 page_owner->order = 0;
209 page_ext = page_ext_next(page_ext);
210 }
211}
212
213void __copy_page_owner(struct page *oldpage, struct page *newpage)
214{
215 struct page_ext *old_ext = lookup_page_ext(oldpage);
216 struct page_ext *new_ext = lookup_page_ext(newpage);
217 struct page_owner *old_page_owner, *new_page_owner;
218
219 if (unlikely(!old_ext || !new_ext))
220 return;
221
222 old_page_owner = get_page_owner(old_ext);
223 new_page_owner = get_page_owner(new_ext);
224 new_page_owner->order = old_page_owner->order;
225 new_page_owner->gfp_mask = old_page_owner->gfp_mask;
226 new_page_owner->last_migrate_reason =
227 old_page_owner->last_migrate_reason;
228 new_page_owner->handle = old_page_owner->handle;
229 new_page_owner->pid = old_page_owner->pid;
230 new_page_owner->ts_nsec = old_page_owner->ts_nsec;
231 new_page_owner->free_ts_nsec = old_page_owner->ts_nsec;
232
233 /*
234 * We don't clear the bit on the oldpage as it's going to be freed
235 * after migration. Until then, the info can be useful in case of
236 * a bug, and the overall stats will be off a bit only temporarily.
237 * Also, migrate_misplaced_transhuge_page() can still fail the
238 * migration and then we want the oldpage to retain the info. But
239 * in that case we also don't need to explicitly clear the info from
240 * the new page, which will be freed.
241 */
242 __set_bit(PAGE_EXT_OWNER, &new_ext->flags);
243 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &new_ext->flags);
244}
245
246void pagetypeinfo_showmixedcount_print(struct seq_file *m,
247 pg_data_t *pgdat, struct zone *zone)
248{
249 struct page *page;
250 struct page_ext *page_ext;
251 struct page_owner *page_owner;
252 unsigned long pfn, block_end_pfn;
253 unsigned long end_pfn = zone_end_pfn(zone);
254 unsigned long count[MIGRATE_TYPES] = { 0, };
255 int pageblock_mt, page_mt;
256 int i;
257
258 /* Scan block by block. First and last block may be incomplete */
259 pfn = zone->zone_start_pfn;
260
261 /*
262 * Walk the zone in pageblock_nr_pages steps. If a page block spans
263 * a zone boundary, it will be double counted between zones. This does
264 * not matter as the mixed block count will still be correct
265 */
266 for (; pfn < end_pfn; ) {
267 page = pfn_to_online_page(pfn);
268 if (!page) {
269 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
270 continue;
271 }
272
273 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
274 block_end_pfn = min(block_end_pfn, end_pfn);
275
276 pageblock_mt = get_pageblock_migratetype(page);
277
278 for (; pfn < block_end_pfn; pfn++) {
279 if (!pfn_valid_within(pfn))
280 continue;
281
282 /* The pageblock is online, no need to recheck. */
283 page = pfn_to_page(pfn);
284
285 if (page_zone(page) != zone)
286 continue;
287
288 if (PageBuddy(page)) {
289 unsigned long freepage_order;
290
291 freepage_order = buddy_order_unsafe(page);
292 if (freepage_order < MAX_ORDER)
293 pfn += (1UL << freepage_order) - 1;
294 continue;
295 }
296
297 if (PageReserved(page))
298 continue;
299
300 page_ext = lookup_page_ext(page);
301 if (unlikely(!page_ext))
302 continue;
303
304 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
305 continue;
306
307 page_owner = get_page_owner(page_ext);
308 page_mt = gfp_migratetype(page_owner->gfp_mask);
309 if (pageblock_mt != page_mt) {
310 if (is_migrate_cma(pageblock_mt))
311 count[MIGRATE_MOVABLE]++;
312 else
313 count[pageblock_mt]++;
314
315 pfn = block_end_pfn;
316 break;
317 }
318 pfn += (1UL << page_owner->order) - 1;
319 }
320 }
321
322 /* Print counts */
323 seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
324 for (i = 0; i < MIGRATE_TYPES; i++)
325 seq_printf(m, "%12lu ", count[i]);
326 seq_putc(m, '\n');
327}
328
329static ssize_t
330print_page_owner(char __user *buf, size_t count, unsigned long pfn,
331 struct page *page, struct page_owner *page_owner,
332 depot_stack_handle_t handle)
333{
334 int ret, pageblock_mt, page_mt;
335 unsigned long *entries;
336 unsigned int nr_entries;
337 char *kbuf;
338
339 count = min_t(size_t, count, PAGE_SIZE);
340 kbuf = kmalloc(count, GFP_KERNEL);
341 if (!kbuf)
342 return -ENOMEM;
343
344 ret = snprintf(kbuf, count,
345 "Page allocated via order %u, mask %#x(%pGg), pid %d, ts %llu ns, free_ts %llu ns\n",
346 page_owner->order, page_owner->gfp_mask,
347 &page_owner->gfp_mask, page_owner->pid,
348 page_owner->ts_nsec, page_owner->free_ts_nsec);
349
350 if (ret >= count)
351 goto err;
352
353 /* Print information relevant to grouping pages by mobility */
354 pageblock_mt = get_pageblock_migratetype(page);
355 page_mt = gfp_migratetype(page_owner->gfp_mask);
356 ret += snprintf(kbuf + ret, count - ret,
357 "PFN %lu type %s Block %lu type %s Flags %#lx(%pGp)\n",
358 pfn,
359 migratetype_names[page_mt],
360 pfn >> pageblock_order,
361 migratetype_names[pageblock_mt],
362 page->flags, &page->flags);
363
364 if (ret >= count)
365 goto err;
366
367 nr_entries = stack_depot_fetch(handle, &entries);
368 ret += stack_trace_snprint(kbuf + ret, count - ret, entries, nr_entries, 0);
369 if (ret >= count)
370 goto err;
371
372 if (page_owner->last_migrate_reason != -1) {
373 ret += snprintf(kbuf + ret, count - ret,
374 "Page has been migrated, last migrate reason: %s\n",
375 migrate_reason_names[page_owner->last_migrate_reason]);
376 if (ret >= count)
377 goto err;
378 }
379
380 ret += snprintf(kbuf + ret, count - ret, "\n");
381 if (ret >= count)
382 goto err;
383
384 if (copy_to_user(buf, kbuf, ret))
385 ret = -EFAULT;
386
387 kfree(kbuf);
388 return ret;
389
390err:
391 kfree(kbuf);
392 return -ENOMEM;
393}
394
395void __dump_page_owner(const struct page *page)
396{
397 struct page_ext *page_ext = lookup_page_ext(page);
398 struct page_owner *page_owner;
399 depot_stack_handle_t handle;
400 unsigned long *entries;
401 unsigned int nr_entries;
402 gfp_t gfp_mask;
403 int mt;
404
405 if (unlikely(!page_ext)) {
406 pr_alert("There is not page extension available.\n");
407 return;
408 }
409
410 page_owner = get_page_owner(page_ext);
411 gfp_mask = page_owner->gfp_mask;
412 mt = gfp_migratetype(gfp_mask);
413
414 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
415 pr_alert("page_owner info is not present (never set?)\n");
416 return;
417 }
418
419 if (test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
420 pr_alert("page_owner tracks the page as allocated\n");
421 else
422 pr_alert("page_owner tracks the page as freed\n");
423
424 pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg), pid %d, ts %llu, free_ts %llu\n",
425 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask,
426 page_owner->pid, page_owner->ts_nsec, page_owner->free_ts_nsec);
427
428 handle = READ_ONCE(page_owner->handle);
429 if (!handle) {
430 pr_alert("page_owner allocation stack trace missing\n");
431 } else {
432 nr_entries = stack_depot_fetch(handle, &entries);
433 stack_trace_print(entries, nr_entries, 0);
434 }
435
436 handle = READ_ONCE(page_owner->free_handle);
437 if (!handle) {
438 pr_alert("page_owner free stack trace missing\n");
439 } else {
440 nr_entries = stack_depot_fetch(handle, &entries);
441 pr_alert("page last free stack trace:\n");
442 stack_trace_print(entries, nr_entries, 0);
443 }
444
445 if (page_owner->last_migrate_reason != -1)
446 pr_alert("page has been migrated, last migrate reason: %s\n",
447 migrate_reason_names[page_owner->last_migrate_reason]);
448}
449
450static ssize_t
451read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
452{
453 unsigned long pfn;
454 struct page *page;
455 struct page_ext *page_ext;
456 struct page_owner *page_owner;
457 depot_stack_handle_t handle;
458
459 if (!static_branch_unlikely(&page_owner_inited))
460 return -EINVAL;
461
462 page = NULL;
463 pfn = min_low_pfn + *ppos;
464
465 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
466 while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
467 pfn++;
468
469 drain_all_pages(NULL);
470
471 /* Find an allocated page */
472 for (; pfn < max_pfn; pfn++) {
473 /*
474 * If the new page is in a new MAX_ORDER_NR_PAGES area,
475 * validate the area as existing, skip it if not
476 */
477 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
478 pfn += MAX_ORDER_NR_PAGES - 1;
479 continue;
480 }
481
482 /* Check for holes within a MAX_ORDER area */
483 if (!pfn_valid_within(pfn))
484 continue;
485
486 page = pfn_to_page(pfn);
487 if (PageBuddy(page)) {
488 unsigned long freepage_order = buddy_order_unsafe(page);
489
490 if (freepage_order < MAX_ORDER)
491 pfn += (1UL << freepage_order) - 1;
492 continue;
493 }
494
495 page_ext = lookup_page_ext(page);
496 if (unlikely(!page_ext))
497 continue;
498
499 /*
500 * Some pages could be missed by concurrent allocation or free,
501 * because we don't hold the zone lock.
502 */
503 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
504 continue;
505
506 /*
507 * Although we do have the info about past allocation of free
508 * pages, it's not relevant for current memory usage.
509 */
510 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
511 continue;
512
513 page_owner = get_page_owner(page_ext);
514
515 /*
516 * Don't print "tail" pages of high-order allocations as that
517 * would inflate the stats.
518 */
519 if (!IS_ALIGNED(pfn, 1 << page_owner->order))
520 continue;
521
522 /*
523 * Access to page_ext->handle isn't synchronous so we should
524 * be careful to access it.
525 */
526 handle = READ_ONCE(page_owner->handle);
527 if (!handle)
528 continue;
529
530 /* Record the next PFN to read in the file offset */
531 *ppos = (pfn - min_low_pfn) + 1;
532
533 return print_page_owner(buf, count, pfn, page,
534 page_owner, handle);
535 }
536
537 return 0;
538}
539
540static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
541{
542 unsigned long pfn = zone->zone_start_pfn;
543 unsigned long end_pfn = zone_end_pfn(zone);
544 unsigned long count = 0;
545
546 /*
547 * Walk the zone in pageblock_nr_pages steps. If a page block spans
548 * a zone boundary, it will be double counted between zones. This does
549 * not matter as the mixed block count will still be correct
550 */
551 for (; pfn < end_pfn; ) {
552 unsigned long block_end_pfn;
553
554 if (!pfn_valid(pfn)) {
555 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
556 continue;
557 }
558
559 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
560 block_end_pfn = min(block_end_pfn, end_pfn);
561
562 for (; pfn < block_end_pfn; pfn++) {
563 struct page *page;
564 struct page_ext *page_ext;
565
566 if (!pfn_valid_within(pfn))
567 continue;
568
569 page = pfn_to_page(pfn);
570
571 if (page_zone(page) != zone)
572 continue;
573
574 /*
575 * To avoid having to grab zone->lock, be a little
576 * careful when reading buddy page order. The only
577 * danger is that we skip too much and potentially miss
578 * some early allocated pages, which is better than
579 * heavy lock contention.
580 */
581 if (PageBuddy(page)) {
582 unsigned long order = buddy_order_unsafe(page);
583
584 if (order > 0 && order < MAX_ORDER)
585 pfn += (1UL << order) - 1;
586 continue;
587 }
588
589 if (PageReserved(page))
590 continue;
591
592 page_ext = lookup_page_ext(page);
593 if (unlikely(!page_ext))
594 continue;
595
596 /* Maybe overlapping zone */
597 if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
598 continue;
599
600 /* Found early allocated page */
601 __set_page_owner_handle(page_ext, early_handle,
602 0, 0);
603 count++;
604 }
605 cond_resched();
606 }
607
608 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
609 pgdat->node_id, zone->name, count);
610}
611
612static void init_zones_in_node(pg_data_t *pgdat)
613{
614 struct zone *zone;
615 struct zone *node_zones = pgdat->node_zones;
616
617 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
618 if (!populated_zone(zone))
619 continue;
620
621 init_pages_in_zone(pgdat, zone);
622 }
623}
624
625static void init_early_allocated_pages(void)
626{
627 pg_data_t *pgdat;
628
629 for_each_online_pgdat(pgdat)
630 init_zones_in_node(pgdat);
631}
632
633static const struct file_operations proc_page_owner_operations = {
634 .read = read_page_owner,
635};
636
637static int __init pageowner_init(void)
638{
639 if (!static_branch_unlikely(&page_owner_inited)) {
640 pr_info("page_owner is disabled\n");
641 return 0;
642 }
643
644 debugfs_create_file("page_owner", 0400, NULL, NULL,
645 &proc_page_owner_operations);
646
647 return 0;
648}
649late_initcall(pageowner_init)
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)