mm/page_owner.c: reduce page_owner structure size
[sfrench/cifs-2.6.git] / mm / page_owner.c
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
38 static int 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
50 static bool need_page_owner(void)
51 {
52         if (page_owner_disabled)
53                 return false;
54
55         return true;
56 }
57
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
72 static noinline void register_dummy_stack(void)
73 {
74         dummy_handle = create_dummy_stack();
75 }
76
77 static noinline void register_failure_stack(void)
78 {
79         failure_handle = create_dummy_stack();
80 }
81
82 static noinline void register_early_stack(void)
83 {
84         early_handle = create_dummy_stack();
85 }
86
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
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
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
123 static inline bool check_recursive_alloc(struct stack_trace *trace,
124                                         unsigned long ip)
125 {
126         int i, count;
127
128         if (!trace->nr_entries)
129                 return false;
130
131         for (i = 0, count = 0; i < trace->nr_entries; i++) {
132                 if (trace->entries[i] == ip && ++count == 2)
133                         return true;
134         }
135
136         return false;
137 }
138
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
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
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
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
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
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
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
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
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
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
529 static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
530 {
531         struct page *page;
532         struct page_ext *page_ext;
533         unsigned long pfn = zone->zone_start_pfn, block_end_pfn;
534         unsigned long end_pfn = pfn + zone->spanned_pages;
535         unsigned long count = 0;
536
537         /* Scan block by block. First and last block may be incomplete */
538         pfn = zone->zone_start_pfn;
539
540         /*
541          * Walk the zone in pageblock_nr_pages steps. If a page block spans
542          * a zone boundary, it will be double counted between zones. This does
543          * not matter as the mixed block count will still be correct
544          */
545         for (; pfn < end_pfn; ) {
546                 if (!pfn_valid(pfn)) {
547                         pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
548                         continue;
549                 }
550
551                 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
552                 block_end_pfn = min(block_end_pfn, end_pfn);
553
554                 page = pfn_to_page(pfn);
555
556                 for (; pfn < block_end_pfn; pfn++) {
557                         if (!pfn_valid_within(pfn))
558                                 continue;
559
560                         page = pfn_to_page(pfn);
561
562                         if (page_zone(page) != zone)
563                                 continue;
564
565                         /*
566                          * To avoid having to grab zone->lock, be a little
567                          * careful when reading buddy page order. The only
568                          * danger is that we skip too much and potentially miss
569                          * some early allocated pages, which is better than
570                          * heavy lock contention.
571                          */
572                         if (PageBuddy(page)) {
573                                 unsigned long order = page_order_unsafe(page);
574
575                                 if (order > 0 && order < MAX_ORDER)
576                                         pfn += (1UL << order) - 1;
577                                 continue;
578                         }
579
580                         if (PageReserved(page))
581                                 continue;
582
583                         page_ext = lookup_page_ext(page);
584                         if (unlikely(!page_ext))
585                                 continue;
586
587                         /* Maybe overlapping zone */
588                         if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
589                                 continue;
590
591                         /* Found early allocated page */
592                         __set_page_owner_handle(page_ext, early_handle, 0, 0);
593                         count++;
594                 }
595                 cond_resched();
596         }
597
598         pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
599                 pgdat->node_id, zone->name, count);
600 }
601
602 static void init_zones_in_node(pg_data_t *pgdat)
603 {
604         struct zone *zone;
605         struct zone *node_zones = pgdat->node_zones;
606
607         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
608                 if (!populated_zone(zone))
609                         continue;
610
611                 init_pages_in_zone(pgdat, zone);
612         }
613 }
614
615 static void init_early_allocated_pages(void)
616 {
617         pg_data_t *pgdat;
618
619         drain_all_pages(NULL);
620         for_each_online_pgdat(pgdat)
621                 init_zones_in_node(pgdat);
622 }
623
624 static const struct file_operations proc_page_owner_operations = {
625         .read           = read_page_owner,
626 };
627
628 static int __init pageowner_init(void)
629 {
630         struct dentry *dentry;
631
632         if (!static_branch_unlikely(&page_owner_inited)) {
633                 pr_info("page_owner is disabled\n");
634                 return 0;
635         }
636
637         dentry = debugfs_create_file("page_owner", S_IRUSR, NULL,
638                         NULL, &proc_page_owner_operations);
639         if (IS_ERR(dentry))
640                 return PTR_ERR(dentry);
641
642         return 0;
643 }
644 late_initcall(pageowner_init)