1// SPDX-License-Identifier: GPL-2.0
2#include <linux/debugfs.h>
3#include <linux/mm.h>
4#include <linux/slab.h>
5#include <linux/uaccess.h>
6#include <linux/memblock.h>
7#include <linux/stacktrace.h>
8#include <linux/page_owner.h>
9#include <linux/jump_label.h>
10#include <linux/migrate.h>
11#include <linux/stackdepot.h>
12#include <linux/seq_file.h>
13
14#include "internal.h"
15
16/*
17 * TODO: teach PAGE_OWNER_STACK_DEPTH (__dump_page_owner and save_stack)
18 * to use off stack temporal storage
19 */
20#define PAGE_OWNER_STACK_DEPTH (16)
21
22struct page_owner {
23 unsigned short order;
24 short last_migrate_reason;
25 gfp_t gfp_mask;
26 depot_stack_handle_t handle;
27};
28
29static bool page_owner_disabled = true;
30DEFINE_STATIC_KEY_FALSE(page_owner_inited);
31
32static depot_stack_handle_t dummy_handle;
33static depot_stack_handle_t failure_handle;
34static depot_stack_handle_t early_handle;
35
36static void init_early_allocated_pages(void);
37
38static int __init early_page_owner_param(char *buf)
39{
40 if (!buf)
41 return -EINVAL;
42
43 if (strcmp(buf, "on") == 0)
44 page_owner_disabled = false;
45
46 return 0;
47}
48early_param("page_owner", early_page_owner_param);
49
50static bool need_page_owner(void)
51{
52 if (page_owner_disabled)
53 return false;
54
55 return true;
56}
57
58static __always_inline depot_stack_handle_t create_dummy_stack(void)
59{
60 unsigned long entries[4];
61 struct stack_trace dummy;
62
63 dummy.nr_entries = 0;
64 dummy.max_entries = ARRAY_SIZE(entries);
65 dummy.entries = &entries[0];
66 dummy.skip = 0;
67
68 save_stack_trace(&dummy);
69 return depot_save_stack(&dummy, GFP_KERNEL);
70}
71
72static noinline void register_dummy_stack(void)
73{
74 dummy_handle = create_dummy_stack();
75}
76
77static noinline void register_failure_stack(void)
78{
79 failure_handle = create_dummy_stack();
80}
81
82static noinline void register_early_stack(void)
83{
84 early_handle = create_dummy_stack();
85}
86
87static void init_page_owner(void)
88{
89 if (page_owner_disabled)
90 return;
91
92 register_dummy_stack();
93 register_failure_stack();
94 register_early_stack();
95 static_branch_enable(&page_owner_inited);
96 init_early_allocated_pages();
97}
98
99struct page_ext_operations page_owner_ops = {
100 .size = sizeof(struct page_owner),
101 .need = need_page_owner,
102 .init = init_page_owner,
103};
104
105static inline struct page_owner *get_page_owner(struct page_ext *page_ext)
106{
107 return (void *)page_ext + page_owner_ops.offset;
108}
109
110void __reset_page_owner(struct page *page, unsigned int order)
111{
112 int i;
113 struct page_ext *page_ext;
114
115 for (i = 0; i < (1 << order); i++) {
116 page_ext = lookup_page_ext(page + i);
117 if (unlikely(!page_ext))
118 continue;
119 __clear_bit(PAGE_EXT_OWNER, &page_ext->flags);
120 }
121}
122
123static inline bool check_recursive_alloc(struct stack_trace *trace,
124 unsigned long ip)
125{
126 int i;
127
128 if (!trace->nr_entries)
129 return false;
130
131 for (i = 0; i < trace->nr_entries; i++) {
132 if (trace->entries[i] == ip)
133 return true;
134 }
135
136 return false;
137}
138
139static noinline depot_stack_handle_t save_stack(gfp_t flags)
140{
141 unsigned long entries[PAGE_OWNER_STACK_DEPTH];
142 struct stack_trace trace = {
143 .nr_entries = 0,
144 .entries = entries,
145 .max_entries = PAGE_OWNER_STACK_DEPTH,
146 .skip = 2
147 };
148 depot_stack_handle_t handle;
149
150 save_stack_trace(&trace);
151 if (trace.nr_entries != 0 &&
152 trace.entries[trace.nr_entries-1] == ULONG_MAX)
153 trace.nr_entries--;
154
155 /*
156 * We need to check recursion here because our request to stackdepot
157 * could trigger memory allocation to save new entry. New memory
158 * allocation would reach here and call depot_save_stack() again
159 * if we don't catch it. There is still not enough memory in stackdepot
160 * so it would try to allocate memory again and loop forever.
161 */
162 if (check_recursive_alloc(&trace, _RET_IP_))
163 return dummy_handle;
164
165 handle = depot_save_stack(&trace, flags);
166 if (!handle)
167 handle = failure_handle;
168
169 return handle;
170}
171
172static inline void __set_page_owner_handle(struct page_ext *page_ext,
173 depot_stack_handle_t handle, unsigned int order, gfp_t gfp_mask)
174{
175 struct page_owner *page_owner;
176
177 page_owner = get_page_owner(page_ext);
178 page_owner->handle = handle;
179 page_owner->order = order;
180 page_owner->gfp_mask = gfp_mask;
181 page_owner->last_migrate_reason = -1;
182
183 __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
184}
185
186noinline void __set_page_owner(struct page *page, unsigned int order,
187 gfp_t gfp_mask)
188{
189 struct page_ext *page_ext = lookup_page_ext(page);
190 depot_stack_handle_t handle;
191
192 if (unlikely(!page_ext))
193 return;
194
195 handle = save_stack(gfp_mask);
196 __set_page_owner_handle(page_ext, handle, order, gfp_mask);
197}
198
199void __set_page_owner_migrate_reason(struct page *page, int reason)
200{
201 struct page_ext *page_ext = lookup_page_ext(page);
202 struct page_owner *page_owner;
203
204 if (unlikely(!page_ext))
205 return;
206
207 page_owner = get_page_owner(page_ext);
208 page_owner->last_migrate_reason = reason;
209}
210
211void __split_page_owner(struct page *page, unsigned int order)
212{
213 int i;
214 struct page_ext *page_ext = lookup_page_ext(page);
215 struct page_owner *page_owner;
216
217 if (unlikely(!page_ext))
218 return;
219
220 page_owner = get_page_owner(page_ext);
221 page_owner->order = 0;
222 for (i = 1; i < (1 << order); i++)
223 __copy_page_owner(page, page + i);
224}
225
226void __copy_page_owner(struct page *oldpage, struct page *newpage)
227{
228 struct page_ext *old_ext = lookup_page_ext(oldpage);
229 struct page_ext *new_ext = lookup_page_ext(newpage);
230 struct page_owner *old_page_owner, *new_page_owner;
231
232 if (unlikely(!old_ext || !new_ext))
233 return;
234
235 old_page_owner = get_page_owner(old_ext);
236 new_page_owner = get_page_owner(new_ext);
237 new_page_owner->order = old_page_owner->order;
238 new_page_owner->gfp_mask = old_page_owner->gfp_mask;
239 new_page_owner->last_migrate_reason =
240 old_page_owner->last_migrate_reason;
241 new_page_owner->handle = old_page_owner->handle;
242
243 /*
244 * We don't clear the bit on the oldpage as it's going to be freed
245 * after migration. Until then, the info can be useful in case of
246 * a bug, and the overal stats will be off a bit only temporarily.
247 * Also, migrate_misplaced_transhuge_page() can still fail the
248 * migration and then we want the oldpage to retain the info. But
249 * in that case we also don't need to explicitly clear the info from
250 * the new page, which will be freed.
251 */
252 __set_bit(PAGE_EXT_OWNER, &new_ext->flags);
253}
254
255void pagetypeinfo_showmixedcount_print(struct seq_file *m,
256 pg_data_t *pgdat, struct zone *zone)
257{
258 struct page *page;
259 struct page_ext *page_ext;
260 struct page_owner *page_owner;
261 unsigned long pfn = zone->zone_start_pfn, block_end_pfn;
262 unsigned long end_pfn = pfn + zone->spanned_pages;
263 unsigned long count[MIGRATE_TYPES] = { 0, };
264 int pageblock_mt, page_mt;
265 int i;
266
267 /* Scan block by block. First and last block may be incomplete */
268 pfn = zone->zone_start_pfn;
269
270 /*
271 * Walk the zone in pageblock_nr_pages steps. If a page block spans
272 * a zone boundary, it will be double counted between zones. This does
273 * not matter as the mixed block count will still be correct
274 */
275 for (; pfn < end_pfn; ) {
276 if (!pfn_valid(pfn)) {
277 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
278 continue;
279 }
280
281 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
282 block_end_pfn = min(block_end_pfn, end_pfn);
283
284 page = pfn_to_page(pfn);
285 pageblock_mt = get_pageblock_migratetype(page);
286
287 for (; pfn < block_end_pfn; pfn++) {
288 if (!pfn_valid_within(pfn))
289 continue;
290
291 page = pfn_to_page(pfn);
292
293 if (page_zone(page) != zone)
294 continue;
295
296 if (PageBuddy(page)) {
297 unsigned long freepage_order;
298
299 freepage_order = page_order_unsafe(page);
300 if (freepage_order < MAX_ORDER)
301 pfn += (1UL << freepage_order) - 1;
302 continue;
303 }
304
305 if (PageReserved(page))
306 continue;
307
308 page_ext = lookup_page_ext(page);
309 if (unlikely(!page_ext))
310 continue;
311
312 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
313 continue;
314
315 page_owner = get_page_owner(page_ext);
316 page_mt = gfpflags_to_migratetype(
317 page_owner->gfp_mask);
318 if (pageblock_mt != page_mt) {
319 if (is_migrate_cma(pageblock_mt))
320 count[MIGRATE_MOVABLE]++;
321 else
322 count[pageblock_mt]++;
323
324 pfn = block_end_pfn;
325 break;
326 }
327 pfn += (1UL << page_owner->order) - 1;
328 }
329 }
330
331 /* Print counts */
332 seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
333 for (i = 0; i < MIGRATE_TYPES; i++)
334 seq_printf(m, "%12lu ", count[i]);
335 seq_putc(m, '\n');
336}
337
338static ssize_t
339print_page_owner(char __user *buf, size_t count, unsigned long pfn,
340 struct page *page, struct page_owner *page_owner,
341 depot_stack_handle_t handle)
342{
343 int ret;
344 int pageblock_mt, page_mt;
345 char *kbuf;
346 unsigned long entries[PAGE_OWNER_STACK_DEPTH];
347 struct stack_trace trace = {
348 .nr_entries = 0,
349 .entries = entries,
350 .max_entries = PAGE_OWNER_STACK_DEPTH,
351 .skip = 0
352 };
353
354 count = min_t(size_t, count, PAGE_SIZE);
355 kbuf = kmalloc(count, GFP_KERNEL);
356 if (!kbuf)
357 return -ENOMEM;
358
359 ret = snprintf(kbuf, count,
360 "Page allocated via order %u, mask %#x(%pGg)\n",
361 page_owner->order, page_owner->gfp_mask,
362 &page_owner->gfp_mask);
363
364 if (ret >= count)
365 goto err;
366
367 /* Print information relevant to grouping pages by mobility */
368 pageblock_mt = get_pageblock_migratetype(page);
369 page_mt = gfpflags_to_migratetype(page_owner->gfp_mask);
370 ret += snprintf(kbuf + ret, count - ret,
371 "PFN %lu type %s Block %lu type %s Flags %#lx(%pGp)\n",
372 pfn,
373 migratetype_names[page_mt],
374 pfn >> pageblock_order,
375 migratetype_names[pageblock_mt],
376 page->flags, &page->flags);
377
378 if (ret >= count)
379 goto err;
380
381 depot_fetch_stack(handle, &trace);
382 ret += snprint_stack_trace(kbuf + ret, count - ret, &trace, 0);
383 if (ret >= count)
384 goto err;
385
386 if (page_owner->last_migrate_reason != -1) {
387 ret += snprintf(kbuf + ret, count - ret,
388 "Page has been migrated, last migrate reason: %s\n",
389 migrate_reason_names[page_owner->last_migrate_reason]);
390 if (ret >= count)
391 goto err;
392 }
393
394 ret += snprintf(kbuf + ret, count - ret, "\n");
395 if (ret >= count)
396 goto err;
397
398 if (copy_to_user(buf, kbuf, ret))
399 ret = -EFAULT;
400
401 kfree(kbuf);
402 return ret;
403
404err:
405 kfree(kbuf);
406 return -ENOMEM;
407}
408
409void __dump_page_owner(struct page *page)
410{
411 struct page_ext *page_ext = lookup_page_ext(page);
412 struct page_owner *page_owner;
413 unsigned long entries[PAGE_OWNER_STACK_DEPTH];
414 struct stack_trace trace = {
415 .nr_entries = 0,
416 .entries = entries,
417 .max_entries = PAGE_OWNER_STACK_DEPTH,
418 .skip = 0
419 };
420 depot_stack_handle_t handle;
421 gfp_t gfp_mask;
422 int mt;
423
424 if (unlikely(!page_ext)) {
425 pr_alert("There is not page extension available.\n");
426 return;
427 }
428
429 page_owner = get_page_owner(page_ext);
430 gfp_mask = page_owner->gfp_mask;
431 mt = gfpflags_to_migratetype(gfp_mask);
432
433 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
434 pr_alert("page_owner info is not active (free page?)\n");
435 return;
436 }
437
438 handle = READ_ONCE(page_owner->handle);
439 if (!handle) {
440 pr_alert("page_owner info is not active (free page?)\n");
441 return;
442 }
443
444 depot_fetch_stack(handle, &trace);
445 pr_alert("page allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n",
446 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask);
447 print_stack_trace(&trace, 0);
448
449 if (page_owner->last_migrate_reason != -1)
450 pr_alert("page has been migrated, last migrate reason: %s\n",
451 migrate_reason_names[page_owner->last_migrate_reason]);
452}
453
454static ssize_t
455read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
456{
457 unsigned long pfn;
458 struct page *page;
459 struct page_ext *page_ext;
460 struct page_owner *page_owner;
461 depot_stack_handle_t handle;
462
463 if (!static_branch_unlikely(&page_owner_inited))
464 return -EINVAL;
465
466 page = NULL;
467 pfn = min_low_pfn + *ppos;
468
469 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
470 while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
471 pfn++;
472
473 drain_all_pages(NULL);
474
475 /* Find an allocated page */
476 for (; pfn < max_pfn; pfn++) {
477 /*
478 * If the new page is in a new MAX_ORDER_NR_PAGES area,
479 * validate the area as existing, skip it if not
480 */
481 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
482 pfn += MAX_ORDER_NR_PAGES - 1;
483 continue;
484 }
485
486 /* Check for holes within a MAX_ORDER area */
487 if (!pfn_valid_within(pfn))
488 continue;
489
490 page = pfn_to_page(pfn);
491 if (PageBuddy(page)) {
492 unsigned long freepage_order = page_order_unsafe(page);
493
494 if (freepage_order < MAX_ORDER)
495 pfn += (1UL << freepage_order) - 1;
496 continue;
497 }
498
499 page_ext = lookup_page_ext(page);
500 if (unlikely(!page_ext))
501 continue;
502
503 /*
504 * Some pages could be missed by concurrent allocation or free,
505 * because we don't hold the zone lock.
506 */
507 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
508 continue;
509
510 page_owner = get_page_owner(page_ext);
511
512 /*
513 * Access to page_ext->handle isn't synchronous so we should
514 * be careful to access it.
515 */
516 handle = READ_ONCE(page_owner->handle);
517 if (!handle)
518 continue;
519
520 /* Record the next PFN to read in the file offset */
521 *ppos = (pfn - min_low_pfn) + 1;
522
523 return print_page_owner(buf, count, pfn, page,
524 page_owner, handle);
525 }
526
527 return 0;
528}
529
530static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
531{
532 unsigned long pfn = zone->zone_start_pfn;
533 unsigned long end_pfn = zone_end_pfn(zone);
534 unsigned long count = 0;
535
536 /*
537 * Walk the zone in pageblock_nr_pages steps. If a page block spans
538 * a zone boundary, it will be double counted between zones. This does
539 * not matter as the mixed block count will still be correct
540 */
541 for (; pfn < end_pfn; ) {
542 unsigned long block_end_pfn;
543
544 if (!pfn_valid(pfn)) {
545 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
546 continue;
547 }
548
549 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
550 block_end_pfn = min(block_end_pfn, end_pfn);
551
552 for (; pfn < block_end_pfn; pfn++) {
553 struct page *page;
554 struct page_ext *page_ext;
555
556 if (!pfn_valid_within(pfn))
557 continue;
558
559 page = pfn_to_page(pfn);
560
561 if (page_zone(page) != zone)
562 continue;
563
564 /*
565 * To avoid having to grab zone->lock, be a little
566 * careful when reading buddy page order. The only
567 * danger is that we skip too much and potentially miss
568 * some early allocated pages, which is better than
569 * heavy lock contention.
570 */
571 if (PageBuddy(page)) {
572 unsigned long order = page_order_unsafe(page);
573
574 if (order > 0 && order < MAX_ORDER)
575 pfn += (1UL << order) - 1;
576 continue;
577 }
578
579 if (PageReserved(page))
580 continue;
581
582 page_ext = lookup_page_ext(page);
583 if (unlikely(!page_ext))
584 continue;
585
586 /* Maybe overlapping zone */
587 if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
588 continue;
589
590 /* Found early allocated page */
591 __set_page_owner_handle(page_ext, early_handle, 0, 0);
592 count++;
593 }
594 cond_resched();
595 }
596
597 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
598 pgdat->node_id, zone->name, count);
599}
600
601static void init_zones_in_node(pg_data_t *pgdat)
602{
603 struct zone *zone;
604 struct zone *node_zones = pgdat->node_zones;
605
606 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
607 if (!populated_zone(zone))
608 continue;
609
610 init_pages_in_zone(pgdat, zone);
611 }
612}
613
614static void init_early_allocated_pages(void)
615{
616 pg_data_t *pgdat;
617
618 for_each_online_pgdat(pgdat)
619 init_zones_in_node(pgdat);
620}
621
622static const struct file_operations proc_page_owner_operations = {
623 .read = read_page_owner,
624};
625
626static int __init pageowner_init(void)
627{
628 if (!static_branch_unlikely(&page_owner_inited)) {
629 pr_info("page_owner is disabled\n");
630 return 0;
631 }
632
633 debugfs_create_file("page_owner", 0400, NULL, NULL,
634 &proc_page_owner_operations);
635
636 return 0;
637}
638late_initcall(pageowner_init)
639