Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/mm/page_owner.c

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

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