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
22 struct page_owner {
23 unsigned short order;
24 short last_migrate_reason;
25 gfp_t gfp_mask;
26 depot_stack_handle_t handle;
27 depot_stack_handle_t free_handle;
28 };
29
30 static bool page_owner_enabled = false;
31 DEFINE_STATIC_KEY_FALSE(page_owner_inited);
32
33 static depot_stack_handle_t dummy_handle;
34 static depot_stack_handle_t failure_handle;
35 static depot_stack_handle_t early_handle;
36
37 static void init_early_allocated_pages(void);
38
early_page_owner_param(char * buf)39 static int __init early_page_owner_param(char *buf)
40 {
41 if (!buf)
42 return -EINVAL;
43
44 if (strcmp(buf, "on") == 0)
45 page_owner_enabled = true;
46
47 return 0;
48 }
49 early_param("page_owner", early_page_owner_param);
50
need_page_owner(void)51 static bool need_page_owner(void)
52 {
53 return page_owner_enabled;
54 }
55
create_dummy_stack(void)56 static __always_inline depot_stack_handle_t create_dummy_stack(void)
57 {
58 unsigned long entries[4];
59 unsigned int nr_entries;
60
61 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
62 return stack_depot_save(entries, nr_entries, GFP_KERNEL);
63 }
64
register_dummy_stack(void)65 static noinline void register_dummy_stack(void)
66 {
67 dummy_handle = create_dummy_stack();
68 }
69
register_failure_stack(void)70 static noinline void register_failure_stack(void)
71 {
72 failure_handle = create_dummy_stack();
73 }
74
register_early_stack(void)75 static noinline void register_early_stack(void)
76 {
77 early_handle = create_dummy_stack();
78 }
79
init_page_owner(void)80 static void init_page_owner(void)
81 {
82 if (!page_owner_enabled)
83 return;
84
85 register_dummy_stack();
86 register_failure_stack();
87 register_early_stack();
88 static_branch_enable(&page_owner_inited);
89 init_early_allocated_pages();
90 }
91
92 struct page_ext_operations page_owner_ops = {
93 .size = sizeof(struct page_owner),
94 .need = need_page_owner,
95 .init = init_page_owner,
96 };
97
get_page_owner(struct page_ext * page_ext)98 static inline struct page_owner *get_page_owner(struct page_ext *page_ext)
99 {
100 return (void *)page_ext + page_owner_ops.offset;
101 }
102
check_recursive_alloc(unsigned long * entries,unsigned int nr_entries,unsigned long ip)103 static inline bool check_recursive_alloc(unsigned long *entries,
104 unsigned int nr_entries,
105 unsigned long ip)
106 {
107 unsigned int i;
108
109 for (i = 0; i < nr_entries; i++) {
110 if (entries[i] == ip)
111 return true;
112 }
113 return false;
114 }
115
save_stack(gfp_t flags)116 static noinline depot_stack_handle_t save_stack(gfp_t flags)
117 {
118 unsigned long entries[PAGE_OWNER_STACK_DEPTH];
119 depot_stack_handle_t handle;
120 unsigned int nr_entries;
121
122 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2);
123
124 /*
125 * We need to check recursion here because our request to
126 * stackdepot could trigger memory allocation to save new
127 * entry. New memory allocation would reach here and call
128 * stack_depot_save_entries() again if we don't catch it. There is
129 * still not enough memory in stackdepot so it would try to
130 * allocate memory again and loop forever.
131 */
132 if (check_recursive_alloc(entries, nr_entries, _RET_IP_))
133 return dummy_handle;
134
135 handle = stack_depot_save(entries, nr_entries, flags);
136 if (!handle)
137 handle = failure_handle;
138
139 return handle;
140 }
141
__reset_page_owner(struct page * page,unsigned int order)142 void __reset_page_owner(struct page *page, unsigned int order)
143 {
144 int i;
145 struct page_ext *page_ext;
146 depot_stack_handle_t handle = 0;
147 struct page_owner *page_owner;
148
149 handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
150
151 page_ext = lookup_page_ext(page);
152 if (unlikely(!page_ext))
153 return;
154 for (i = 0; i < (1 << order); i++) {
155 __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
156 page_owner = get_page_owner(page_ext);
157 page_owner->free_handle = handle;
158 page_ext = page_ext_next(page_ext);
159 }
160 }
161
__set_page_owner_handle(struct page * page,struct page_ext * page_ext,depot_stack_handle_t handle,unsigned int order,gfp_t gfp_mask)162 static inline void __set_page_owner_handle(struct page *page,
163 struct page_ext *page_ext, depot_stack_handle_t handle,
164 unsigned int order, gfp_t gfp_mask)
165 {
166 struct page_owner *page_owner;
167 int i;
168
169 for (i = 0; i < (1 << order); i++) {
170 page_owner = get_page_owner(page_ext);
171 page_owner->handle = handle;
172 page_owner->order = order;
173 page_owner->gfp_mask = gfp_mask;
174 page_owner->last_migrate_reason = -1;
175 __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
176 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
177
178 page_ext = page_ext_next(page_ext);
179 }
180 }
181
__set_page_owner(struct page * page,unsigned int order,gfp_t gfp_mask)182 noinline void __set_page_owner(struct page *page, unsigned int order,
183 gfp_t gfp_mask)
184 {
185 struct page_ext *page_ext = lookup_page_ext(page);
186 depot_stack_handle_t handle;
187
188 if (unlikely(!page_ext))
189 return;
190
191 handle = save_stack(gfp_mask);
192 __set_page_owner_handle(page, page_ext, handle, order, gfp_mask);
193 }
194
__set_page_owner_migrate_reason(struct page * page,int reason)195 void __set_page_owner_migrate_reason(struct page *page, int reason)
196 {
197 struct page_ext *page_ext = lookup_page_ext(page);
198 struct page_owner *page_owner;
199
200 if (unlikely(!page_ext))
201 return;
202
203 page_owner = get_page_owner(page_ext);
204 page_owner->last_migrate_reason = reason;
205 }
206
__split_page_owner(struct page * page,unsigned int nr)207 void __split_page_owner(struct page *page, unsigned int nr)
208 {
209 int i;
210 struct page_ext *page_ext = lookup_page_ext(page);
211 struct page_owner *page_owner;
212
213 if (unlikely(!page_ext))
214 return;
215
216 for (i = 0; i < nr; i++) {
217 page_owner = get_page_owner(page_ext);
218 page_owner->order = 0;
219 page_ext = page_ext_next(page_ext);
220 }
221 }
222
__copy_page_owner(struct page * oldpage,struct page * newpage)223 void __copy_page_owner(struct page *oldpage, struct page *newpage)
224 {
225 struct page_ext *old_ext = lookup_page_ext(oldpage);
226 struct page_ext *new_ext = lookup_page_ext(newpage);
227 struct page_owner *old_page_owner, *new_page_owner;
228
229 if (unlikely(!old_ext || !new_ext))
230 return;
231
232 old_page_owner = get_page_owner(old_ext);
233 new_page_owner = get_page_owner(new_ext);
234 new_page_owner->order = old_page_owner->order;
235 new_page_owner->gfp_mask = old_page_owner->gfp_mask;
236 new_page_owner->last_migrate_reason =
237 old_page_owner->last_migrate_reason;
238 new_page_owner->handle = old_page_owner->handle;
239
240 /*
241 * We don't clear the bit on the oldpage as it's going to be freed
242 * after migration. Until then, the info can be useful in case of
243 * a bug, and the overal stats will be off a bit only temporarily.
244 * Also, migrate_misplaced_transhuge_page() can still fail the
245 * migration and then we want the oldpage to retain the info. But
246 * in that case we also don't need to explicitly clear the info from
247 * the new page, which will be freed.
248 */
249 __set_bit(PAGE_EXT_OWNER, &new_ext->flags);
250 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &new_ext->flags);
251 }
252
pagetypeinfo_showmixedcount_print(struct seq_file * m,pg_data_t * pgdat,struct zone * zone)253 void pagetypeinfo_showmixedcount_print(struct seq_file *m,
254 pg_data_t *pgdat, struct zone *zone)
255 {
256 struct page *page;
257 struct page_ext *page_ext;
258 struct page_owner *page_owner;
259 unsigned long pfn = zone->zone_start_pfn, block_end_pfn;
260 unsigned long end_pfn = pfn + zone->spanned_pages;
261 unsigned long count[MIGRATE_TYPES] = { 0, };
262 int pageblock_mt, page_mt;
263 int i;
264
265 /* Scan block by block. First and last block may be incomplete */
266 pfn = zone->zone_start_pfn;
267
268 /*
269 * Walk the zone in pageblock_nr_pages steps. If a page block spans
270 * a zone boundary, it will be double counted between zones. This does
271 * not matter as the mixed block count will still be correct
272 */
273 for (; pfn < end_pfn; ) {
274 page = pfn_to_online_page(pfn);
275 if (!page) {
276 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
277 continue;
278 }
279
280 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
281 block_end_pfn = min(block_end_pfn, end_pfn);
282
283 pageblock_mt = get_pageblock_migratetype(page);
284
285 for (; pfn < block_end_pfn; pfn++) {
286 if (!pfn_valid_within(pfn))
287 continue;
288
289 /* The pageblock is online, no need to recheck. */
290 page = pfn_to_page(pfn);
291
292 if (page_zone(page) != zone)
293 continue;
294
295 if (PageBuddy(page)) {
296 unsigned long freepage_order;
297
298 freepage_order = buddy_order_unsafe(page);
299 if (freepage_order < MAX_ORDER)
300 pfn += (1UL << freepage_order) - 1;
301 continue;
302 }
303
304 if (PageReserved(page))
305 continue;
306
307 page_ext = lookup_page_ext(page);
308 if (unlikely(!page_ext))
309 continue;
310
311 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
312 continue;
313
314 page_owner = get_page_owner(page_ext);
315 page_mt = gfp_migratetype(page_owner->gfp_mask);
316 if (pageblock_mt != page_mt) {
317 if (is_migrate_cma(pageblock_mt))
318 count[MIGRATE_MOVABLE]++;
319 else
320 count[pageblock_mt]++;
321
322 pfn = block_end_pfn;
323 break;
324 }
325 pfn += (1UL << page_owner->order) - 1;
326 }
327 }
328
329 /* Print counts */
330 seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
331 for (i = 0; i < MIGRATE_TYPES; i++)
332 seq_printf(m, "%12lu ", count[i]);
333 seq_putc(m, '\n');
334 }
335
336 static ssize_t
print_page_owner(char __user * buf,size_t count,unsigned long pfn,struct page * page,struct page_owner * page_owner,depot_stack_handle_t handle)337 print_page_owner(char __user *buf, size_t count, unsigned long pfn,
338 struct page *page, struct page_owner *page_owner,
339 depot_stack_handle_t handle)
340 {
341 int ret, pageblock_mt, page_mt;
342 unsigned long *entries;
343 unsigned int nr_entries;
344 char *kbuf;
345
346 count = min_t(size_t, count, PAGE_SIZE);
347 kbuf = kmalloc(count, GFP_KERNEL);
348 if (!kbuf)
349 return -ENOMEM;
350
351 ret = snprintf(kbuf, count,
352 "Page allocated via order %u, mask %#x(%pGg)\n",
353 page_owner->order, page_owner->gfp_mask,
354 &page_owner->gfp_mask);
355
356 if (ret >= count)
357 goto err;
358
359 /* Print information relevant to grouping pages by mobility */
360 pageblock_mt = get_pageblock_migratetype(page);
361 page_mt = gfp_migratetype(page_owner->gfp_mask);
362 ret += snprintf(kbuf + ret, count - ret,
363 "PFN %lu type %s Block %lu type %s Flags %#lx(%pGp)\n",
364 pfn,
365 migratetype_names[page_mt],
366 pfn >> pageblock_order,
367 migratetype_names[pageblock_mt],
368 page->flags, &page->flags);
369
370 if (ret >= count)
371 goto err;
372
373 nr_entries = stack_depot_fetch(handle, &entries);
374 ret += stack_trace_snprint(kbuf + ret, count - ret, entries, nr_entries, 0);
375 if (ret >= count)
376 goto err;
377
378 if (page_owner->last_migrate_reason != -1) {
379 ret += snprintf(kbuf + ret, count - ret,
380 "Page has been migrated, last migrate reason: %s\n",
381 migrate_reason_names[page_owner->last_migrate_reason]);
382 if (ret >= count)
383 goto err;
384 }
385
386 ret += snprintf(kbuf + ret, count - ret, "\n");
387 if (ret >= count)
388 goto err;
389
390 if (copy_to_user(buf, kbuf, ret))
391 ret = -EFAULT;
392
393 kfree(kbuf);
394 return ret;
395
396 err:
397 kfree(kbuf);
398 return -ENOMEM;
399 }
400
__dump_page_owner(struct page * page)401 void __dump_page_owner(struct page *page)
402 {
403 struct page_ext *page_ext = lookup_page_ext(page);
404 struct page_owner *page_owner;
405 depot_stack_handle_t handle;
406 unsigned long *entries;
407 unsigned int nr_entries;
408 gfp_t gfp_mask;
409 int mt;
410
411 if (unlikely(!page_ext)) {
412 pr_alert("There is not page extension available.\n");
413 return;
414 }
415
416 page_owner = get_page_owner(page_ext);
417 gfp_mask = page_owner->gfp_mask;
418 mt = gfp_migratetype(gfp_mask);
419
420 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
421 pr_alert("page_owner info is not present (never set?)\n");
422 return;
423 }
424
425 if (test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
426 pr_alert("page_owner tracks the page as allocated\n");
427 else
428 pr_alert("page_owner tracks the page as freed\n");
429
430 pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n",
431 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask);
432
433 handle = READ_ONCE(page_owner->handle);
434 if (!handle) {
435 pr_alert("page_owner allocation stack trace missing\n");
436 } else {
437 nr_entries = stack_depot_fetch(handle, &entries);
438 stack_trace_print(entries, nr_entries, 0);
439 }
440
441 handle = READ_ONCE(page_owner->free_handle);
442 if (!handle) {
443 pr_alert("page_owner free stack trace missing\n");
444 } else {
445 nr_entries = stack_depot_fetch(handle, &entries);
446 pr_alert("page last free stack trace:\n");
447 stack_trace_print(entries, nr_entries, 0);
448 }
449
450 if (page_owner->last_migrate_reason != -1)
451 pr_alert("page has been migrated, last migrate reason: %s\n",
452 migrate_reason_names[page_owner->last_migrate_reason]);
453 }
454
455 static ssize_t
read_page_owner(struct file * file,char __user * buf,size_t count,loff_t * ppos)456 read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
457 {
458 unsigned long pfn;
459 struct page *page;
460 struct page_ext *page_ext;
461 struct page_owner *page_owner;
462 depot_stack_handle_t handle;
463
464 if (!static_branch_unlikely(&page_owner_inited))
465 return -EINVAL;
466
467 page = NULL;
468 pfn = min_low_pfn + *ppos;
469
470 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
471 while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
472 pfn++;
473
474 drain_all_pages(NULL);
475
476 /* Find an allocated page */
477 for (; pfn < max_pfn; pfn++) {
478 /*
479 * If the new page is in a new MAX_ORDER_NR_PAGES area,
480 * validate the area as existing, skip it if not
481 */
482 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
483 pfn += MAX_ORDER_NR_PAGES - 1;
484 continue;
485 }
486
487 /* Check for holes within a MAX_ORDER area */
488 if (!pfn_valid_within(pfn))
489 continue;
490
491 page = pfn_to_page(pfn);
492 if (PageBuddy(page)) {
493 unsigned long freepage_order = buddy_order_unsafe(page);
494
495 if (freepage_order < MAX_ORDER)
496 pfn += (1UL << freepage_order) - 1;
497 continue;
498 }
499
500 page_ext = lookup_page_ext(page);
501 if (unlikely(!page_ext))
502 continue;
503
504 /*
505 * Some pages could be missed by concurrent allocation or free,
506 * because we don't hold the zone lock.
507 */
508 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
509 continue;
510
511 /*
512 * Although we do have the info about past allocation of free
513 * pages, it's not relevant for current memory usage.
514 */
515 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
516 continue;
517
518 page_owner = get_page_owner(page_ext);
519
520 /*
521 * Don't print "tail" pages of high-order allocations as that
522 * would inflate the stats.
523 */
524 if (!IS_ALIGNED(pfn, 1 << page_owner->order))
525 continue;
526
527 /*
528 * Access to page_ext->handle isn't synchronous so we should
529 * be careful to access it.
530 */
531 handle = READ_ONCE(page_owner->handle);
532 if (!handle)
533 continue;
534
535 /* Record the next PFN to read in the file offset */
536 *ppos = (pfn - min_low_pfn) + 1;
537
538 return print_page_owner(buf, count, pfn, page,
539 page_owner, handle);
540 }
541
542 return 0;
543 }
544
init_pages_in_zone(pg_data_t * pgdat,struct zone * zone)545 static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
546 {
547 unsigned long pfn = zone->zone_start_pfn;
548 unsigned long end_pfn = zone_end_pfn(zone);
549 unsigned long count = 0;
550
551 /*
552 * Walk the zone in pageblock_nr_pages steps. If a page block spans
553 * a zone boundary, it will be double counted between zones. This does
554 * not matter as the mixed block count will still be correct
555 */
556 for (; pfn < end_pfn; ) {
557 unsigned long block_end_pfn;
558
559 if (!pfn_valid(pfn)) {
560 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
561 continue;
562 }
563
564 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
565 block_end_pfn = min(block_end_pfn, end_pfn);
566
567 for (; pfn < block_end_pfn; pfn++) {
568 struct page *page;
569 struct page_ext *page_ext;
570
571 if (!pfn_valid_within(pfn))
572 continue;
573
574 page = pfn_to_page(pfn);
575
576 if (page_zone(page) != zone)
577 continue;
578
579 /*
580 * To avoid having to grab zone->lock, be a little
581 * careful when reading buddy page order. The only
582 * danger is that we skip too much and potentially miss
583 * some early allocated pages, which is better than
584 * heavy lock contention.
585 */
586 if (PageBuddy(page)) {
587 unsigned long order = buddy_order_unsafe(page);
588
589 if (order > 0 && order < MAX_ORDER)
590 pfn += (1UL << order) - 1;
591 continue;
592 }
593
594 if (PageReserved(page))
595 continue;
596
597 page_ext = lookup_page_ext(page);
598 if (unlikely(!page_ext))
599 continue;
600
601 /* Maybe overlapping zone */
602 if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
603 continue;
604
605 /* Found early allocated page */
606 __set_page_owner_handle(page, page_ext, early_handle,
607 0, 0);
608 count++;
609 }
610 cond_resched();
611 }
612
613 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
614 pgdat->node_id, zone->name, count);
615 }
616
init_zones_in_node(pg_data_t * pgdat)617 static void init_zones_in_node(pg_data_t *pgdat)
618 {
619 struct zone *zone;
620 struct zone *node_zones = pgdat->node_zones;
621
622 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
623 if (!populated_zone(zone))
624 continue;
625
626 init_pages_in_zone(pgdat, zone);
627 }
628 }
629
init_early_allocated_pages(void)630 static void init_early_allocated_pages(void)
631 {
632 pg_data_t *pgdat;
633
634 for_each_online_pgdat(pgdat)
635 init_zones_in_node(pgdat);
636 }
637
638 static const struct file_operations proc_page_owner_operations = {
639 .read = read_page_owner,
640 };
641
pageowner_init(void)642 static int __init pageowner_init(void)
643 {
644 if (!static_branch_unlikely(&page_owner_inited)) {
645 pr_info("page_owner is disabled\n");
646 return 0;
647 }
648
649 debugfs_create_file("page_owner", 0400, NULL, NULL,
650 &proc_page_owner_operations);
651
652 return 0;
653 }
654 late_initcall(pageowner_init)
655
