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/bootmem.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 };
28
29 static bool page_owner_disabled = true;
30 DEFINE_STATIC_KEY_FALSE(page_owner_inited);
31
32 static depot_stack_handle_t dummy_handle;
33 static depot_stack_handle_t failure_handle;
34 static depot_stack_handle_t early_handle;
35
36 static void init_early_allocated_pages(void);
37
early_page_owner_param(char * buf)38 static 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 }
48 early_param("page_owner", early_page_owner_param);
49
need_page_owner(void)50 static bool need_page_owner(void)
51 {
52 if (page_owner_disabled)
53 return false;
54
55 return true;
56 }
57
create_dummy_stack(void)58 static __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
register_dummy_stack(void)72 static noinline void register_dummy_stack(void)
73 {
74 dummy_handle = create_dummy_stack();
75 }
76
register_failure_stack(void)77 static noinline void register_failure_stack(void)
78 {
79 failure_handle = create_dummy_stack();
80 }
81
register_early_stack(void)82 static noinline void register_early_stack(void)
83 {
84 early_handle = create_dummy_stack();
85 }
86
init_page_owner(void)87 static 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
99 struct page_ext_operations page_owner_ops = {
100 .size = sizeof(struct page_owner),
101 .need = need_page_owner,
102 .init = init_page_owner,
103 };
104
get_page_owner(struct page_ext * page_ext)105 static inline struct page_owner *get_page_owner(struct page_ext *page_ext)
106 {
107 return (void *)page_ext + page_owner_ops.offset;
108 }
109
__reset_page_owner(struct page * page,unsigned int order)110 void __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
check_recursive_alloc(struct stack_trace * trace,unsigned long ip)123 static 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
save_stack(gfp_t flags)139 static 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
__set_page_owner_handle(struct page_ext * page_ext,depot_stack_handle_t handle,unsigned int order,gfp_t gfp_mask)172 static 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
__set_page_owner(struct page * page,unsigned int order,gfp_t gfp_mask)186 noinline 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
__set_page_owner_migrate_reason(struct page * page,int reason)199 void __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
__split_page_owner(struct page * page,unsigned int order)211 void __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
__copy_page_owner(struct page * oldpage,struct page * newpage)226 void __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
pagetypeinfo_showmixedcount_print(struct seq_file * m,pg_data_t * pgdat,struct zone * zone)255 void 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
338 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)339 print_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 kbuf = kmalloc(count, GFP_KERNEL);
355 if (!kbuf)
356 return -ENOMEM;
357
358 ret = snprintf(kbuf, count,
359 "Page allocated via order %u, mask %#x(%pGg)\n",
360 page_owner->order, page_owner->gfp_mask,
361 &page_owner->gfp_mask);
362
363 if (ret >= count)
364 goto err;
365
366 /* Print information relevant to grouping pages by mobility */
367 pageblock_mt = get_pageblock_migratetype(page);
368 page_mt = gfpflags_to_migratetype(page_owner->gfp_mask);
369 ret += snprintf(kbuf + ret, count - ret,
370 "PFN %lu type %s Block %lu type %s Flags %#lx(%pGp)\n",
371 pfn,
372 migratetype_names[page_mt],
373 pfn >> pageblock_order,
374 migratetype_names[pageblock_mt],
375 page->flags, &page->flags);
376
377 if (ret >= count)
378 goto err;
379
380 depot_fetch_stack(handle, &trace);
381 ret += snprint_stack_trace(kbuf + ret, count - ret, &trace, 0);
382 if (ret >= count)
383 goto err;
384
385 if (page_owner->last_migrate_reason != -1) {
386 ret += snprintf(kbuf + ret, count - ret,
387 "Page has been migrated, last migrate reason: %s\n",
388 migrate_reason_names[page_owner->last_migrate_reason]);
389 if (ret >= count)
390 goto err;
391 }
392
393 ret += snprintf(kbuf + ret, count - ret, "\n");
394 if (ret >= count)
395 goto err;
396
397 if (copy_to_user(buf, kbuf, ret))
398 ret = -EFAULT;
399
400 kfree(kbuf);
401 return ret;
402
403 err:
404 kfree(kbuf);
405 return -ENOMEM;
406 }
407
__dump_page_owner(struct page * page)408 void __dump_page_owner(struct page *page)
409 {
410 struct page_ext *page_ext = lookup_page_ext(page);
411 struct page_owner *page_owner;
412 unsigned long entries[PAGE_OWNER_STACK_DEPTH];
413 struct stack_trace trace = {
414 .nr_entries = 0,
415 .entries = entries,
416 .max_entries = PAGE_OWNER_STACK_DEPTH,
417 .skip = 0
418 };
419 depot_stack_handle_t handle;
420 gfp_t gfp_mask;
421 int mt;
422
423 if (unlikely(!page_ext)) {
424 pr_alert("There is not page extension available.\n");
425 return;
426 }
427
428 page_owner = get_page_owner(page_ext);
429 gfp_mask = page_owner->gfp_mask;
430 mt = gfpflags_to_migratetype(gfp_mask);
431
432 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
433 pr_alert("page_owner info is not active (free page?)\n");
434 return;
435 }
436
437 handle = READ_ONCE(page_owner->handle);
438 if (!handle) {
439 pr_alert("page_owner info is not active (free page?)\n");
440 return;
441 }
442
443 depot_fetch_stack(handle, &trace);
444 pr_alert("page allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n",
445 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask);
446 print_stack_trace(&trace, 0);
447
448 if (page_owner->last_migrate_reason != -1)
449 pr_alert("page has been migrated, last migrate reason: %s\n",
450 migrate_reason_names[page_owner->last_migrate_reason]);
451 }
452
453 static ssize_t
read_page_owner(struct file * file,char __user * buf,size_t count,loff_t * ppos)454 read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
455 {
456 unsigned long pfn;
457 struct page *page;
458 struct page_ext *page_ext;
459 struct page_owner *page_owner;
460 depot_stack_handle_t handle;
461
462 if (!static_branch_unlikely(&page_owner_inited))
463 return -EINVAL;
464
465 page = NULL;
466 pfn = min_low_pfn + *ppos;
467
468 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
469 while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
470 pfn++;
471
472 drain_all_pages(NULL);
473
474 /* Find an allocated page */
475 for (; pfn < max_pfn; pfn++) {
476 /*
477 * If the new page is in a new MAX_ORDER_NR_PAGES area,
478 * validate the area as existing, skip it if not
479 */
480 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
481 pfn += MAX_ORDER_NR_PAGES - 1;
482 continue;
483 }
484
485 /* Check for holes within a MAX_ORDER area */
486 if (!pfn_valid_within(pfn))
487 continue;
488
489 page = pfn_to_page(pfn);
490 if (PageBuddy(page)) {
491 unsigned long freepage_order = page_order_unsafe(page);
492
493 if (freepage_order < MAX_ORDER)
494 pfn += (1UL << freepage_order) - 1;
495 continue;
496 }
497
498 page_ext = lookup_page_ext(page);
499 if (unlikely(!page_ext))
500 continue;
501
502 /*
503 * Some pages could be missed by concurrent allocation or free,
504 * because we don't hold the zone lock.
505 */
506 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
507 continue;
508
509 page_owner = get_page_owner(page_ext);
510
511 /*
512 * Access to page_ext->handle isn't synchronous so we should
513 * be careful to access it.
514 */
515 handle = READ_ONCE(page_owner->handle);
516 if (!handle)
517 continue;
518
519 /* Record the next PFN to read in the file offset */
520 *ppos = (pfn - min_low_pfn) + 1;
521
522 return print_page_owner(buf, count, pfn, page,
523 page_owner, handle);
524 }
525
526 return 0;
527 }
528
init_pages_in_zone(pg_data_t * pgdat,struct zone * zone)529 static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
530 {
531 unsigned long pfn = zone->zone_start_pfn;
532 unsigned long end_pfn = zone_end_pfn(zone);
533 unsigned long count = 0;
534
535 /*
536 * Walk the zone in pageblock_nr_pages steps. If a page block spans
537 * a zone boundary, it will be double counted between zones. This does
538 * not matter as the mixed block count will still be correct
539 */
540 for (; pfn < end_pfn; ) {
541 unsigned long block_end_pfn;
542
543 if (!pfn_valid(pfn)) {
544 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
545 continue;
546 }
547
548 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
549 block_end_pfn = min(block_end_pfn, end_pfn);
550
551 for (; pfn < block_end_pfn; pfn++) {
552 struct page *page;
553 struct page_ext *page_ext;
554
555 if (!pfn_valid_within(pfn))
556 continue;
557
558 page = pfn_to_page(pfn);
559
560 if (page_zone(page) != zone)
561 continue;
562
563 /*
564 * To avoid having to grab zone->lock, be a little
565 * careful when reading buddy page order. The only
566 * danger is that we skip too much and potentially miss
567 * some early allocated pages, which is better than
568 * heavy lock contention.
569 */
570 if (PageBuddy(page)) {
571 unsigned long order = page_order_unsafe(page);
572
573 if (order > 0 && order < MAX_ORDER)
574 pfn += (1UL << order) - 1;
575 continue;
576 }
577
578 if (PageReserved(page))
579 continue;
580
581 page_ext = lookup_page_ext(page);
582 if (unlikely(!page_ext))
583 continue;
584
585 /* Maybe overlapping zone */
586 if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
587 continue;
588
589 /* Found early allocated page */
590 __set_page_owner_handle(page_ext, early_handle, 0, 0);
591 count++;
592 }
593 cond_resched();
594 }
595
596 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
597 pgdat->node_id, zone->name, count);
598 }
599
init_zones_in_node(pg_data_t * pgdat)600 static void init_zones_in_node(pg_data_t *pgdat)
601 {
602 struct zone *zone;
603 struct zone *node_zones = pgdat->node_zones;
604
605 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
606 if (!populated_zone(zone))
607 continue;
608
609 init_pages_in_zone(pgdat, zone);
610 }
611 }
612
init_early_allocated_pages(void)613 static void init_early_allocated_pages(void)
614 {
615 pg_data_t *pgdat;
616
617 for_each_online_pgdat(pgdat)
618 init_zones_in_node(pgdat);
619 }
620
621 static const struct file_operations proc_page_owner_operations = {
622 .read = read_page_owner,
623 };
624
pageowner_init(void)625 static int __init pageowner_init(void)
626 {
627 struct dentry *dentry;
628
629 if (!static_branch_unlikely(&page_owner_inited)) {
630 pr_info("page_owner is disabled\n");
631 return 0;
632 }
633
634 dentry = debugfs_create_file("page_owner", 0400, NULL,
635 NULL, &proc_page_owner_operations);
636
637 return PTR_ERR_OR_ZERO(dentry);
638 }
639 late_initcall(pageowner_init)
640
