1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/debugfs.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 #include <linux/memcontrol.h>
14 #include <linux/sched/clock.h>
19 * TODO: teach PAGE_OWNER_STACK_DEPTH (__dump_page_owner and save_stack)
20 * to use off stack temporal storage
22 #define PAGE_OWNER_STACK_DEPTH (16)
26 short last_migrate_reason;
28 depot_stack_handle_t handle;
29 depot_stack_handle_t free_handle;
32 char comm[TASK_COMM_LEN];
39 static bool page_owner_enabled __initdata;
40 DEFINE_STATIC_KEY_FALSE(page_owner_inited);
42 static depot_stack_handle_t dummy_handle;
43 static depot_stack_handle_t failure_handle;
44 static depot_stack_handle_t early_handle;
46 static void init_early_allocated_pages(void);
48 static int __init early_page_owner_param(char *buf)
50 int ret = kstrtobool(buf, &page_owner_enabled);
52 if (page_owner_enabled)
53 stack_depot_request_early_init();
57 early_param("page_owner", early_page_owner_param);
59 static __init bool need_page_owner(void)
61 return page_owner_enabled;
64 static __always_inline depot_stack_handle_t create_dummy_stack(void)
66 unsigned long entries[4];
67 unsigned int nr_entries;
69 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
70 return stack_depot_save(entries, nr_entries, GFP_KERNEL);
73 static noinline void register_dummy_stack(void)
75 dummy_handle = create_dummy_stack();
78 static noinline void register_failure_stack(void)
80 failure_handle = create_dummy_stack();
83 static noinline void register_early_stack(void)
85 early_handle = create_dummy_stack();
88 static __init void init_page_owner(void)
90 if (!page_owner_enabled)
93 register_dummy_stack();
94 register_failure_stack();
95 register_early_stack();
96 static_branch_enable(&page_owner_inited);
97 init_early_allocated_pages();
100 struct page_ext_operations page_owner_ops = {
101 .size = sizeof(struct page_owner),
102 .need = need_page_owner,
103 .init = init_page_owner,
104 .need_shared_flags = true,
107 static inline struct page_owner *get_page_owner(struct page_ext *page_ext)
109 return page_ext_data(page_ext, &page_owner_ops);
112 static noinline depot_stack_handle_t save_stack(gfp_t flags)
114 unsigned long entries[PAGE_OWNER_STACK_DEPTH];
115 depot_stack_handle_t handle;
116 unsigned int nr_entries;
121 * Sometimes page metadata allocation tracking requires more
122 * memory to be allocated:
123 * - when new stack trace is saved to stack depot
125 if (current->in_page_owner)
127 current->in_page_owner = 1;
129 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2);
130 handle = stack_depot_save(entries, nr_entries, flags);
132 handle = failure_handle;
134 current->in_page_owner = 0;
138 void __reset_page_owner(struct page *page, unsigned short order)
141 struct page_ext *page_ext;
142 depot_stack_handle_t handle;
143 struct page_owner *page_owner;
144 u64 free_ts_nsec = local_clock();
146 page_ext = page_ext_get(page);
147 if (unlikely(!page_ext))
150 handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
151 for (i = 0; i < (1 << order); i++) {
152 __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
153 page_owner = get_page_owner(page_ext);
154 page_owner->free_handle = handle;
155 page_owner->free_ts_nsec = free_ts_nsec;
156 page_owner->free_pid = current->pid;
157 page_owner->free_tgid = current->tgid;
158 page_ext = page_ext_next(page_ext);
160 page_ext_put(page_ext);
163 static inline void __set_page_owner_handle(struct page_ext *page_ext,
164 depot_stack_handle_t handle,
165 unsigned short order, gfp_t gfp_mask)
167 struct page_owner *page_owner;
169 u64 ts_nsec = local_clock();
171 for (i = 0; i < (1 << order); i++) {
172 page_owner = get_page_owner(page_ext);
173 page_owner->handle = handle;
174 page_owner->order = order;
175 page_owner->gfp_mask = gfp_mask;
176 page_owner->last_migrate_reason = -1;
177 page_owner->pid = current->pid;
178 page_owner->tgid = current->tgid;
179 page_owner->ts_nsec = ts_nsec;
180 strscpy(page_owner->comm, current->comm,
181 sizeof(page_owner->comm));
182 __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
183 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
185 page_ext = page_ext_next(page_ext);
189 noinline void __set_page_owner(struct page *page, unsigned short order,
192 struct page_ext *page_ext;
193 depot_stack_handle_t handle;
195 handle = save_stack(gfp_mask);
197 page_ext = page_ext_get(page);
198 if (unlikely(!page_ext))
200 __set_page_owner_handle(page_ext, handle, order, gfp_mask);
201 page_ext_put(page_ext);
204 void __set_page_owner_migrate_reason(struct page *page, int reason)
206 struct page_ext *page_ext = page_ext_get(page);
207 struct page_owner *page_owner;
209 if (unlikely(!page_ext))
212 page_owner = get_page_owner(page_ext);
213 page_owner->last_migrate_reason = reason;
214 page_ext_put(page_ext);
217 void __split_page_owner(struct page *page, unsigned int nr)
220 struct page_ext *page_ext = page_ext_get(page);
221 struct page_owner *page_owner;
223 if (unlikely(!page_ext))
226 for (i = 0; i < nr; i++) {
227 page_owner = get_page_owner(page_ext);
228 page_owner->order = 0;
229 page_ext = page_ext_next(page_ext);
231 page_ext_put(page_ext);
234 void __folio_copy_owner(struct folio *newfolio, struct folio *old)
236 struct page_ext *old_ext;
237 struct page_ext *new_ext;
238 struct page_owner *old_page_owner, *new_page_owner;
240 old_ext = page_ext_get(&old->page);
241 if (unlikely(!old_ext))
244 new_ext = page_ext_get(&newfolio->page);
245 if (unlikely(!new_ext)) {
246 page_ext_put(old_ext);
250 old_page_owner = get_page_owner(old_ext);
251 new_page_owner = get_page_owner(new_ext);
252 new_page_owner->order = old_page_owner->order;
253 new_page_owner->gfp_mask = old_page_owner->gfp_mask;
254 new_page_owner->last_migrate_reason =
255 old_page_owner->last_migrate_reason;
256 new_page_owner->handle = old_page_owner->handle;
257 new_page_owner->pid = old_page_owner->pid;
258 new_page_owner->tgid = old_page_owner->tgid;
259 new_page_owner->free_pid = old_page_owner->free_pid;
260 new_page_owner->free_tgid = old_page_owner->free_tgid;
261 new_page_owner->ts_nsec = old_page_owner->ts_nsec;
262 new_page_owner->free_ts_nsec = old_page_owner->ts_nsec;
263 strcpy(new_page_owner->comm, old_page_owner->comm);
266 * We don't clear the bit on the old folio as it's going to be freed
267 * after migration. Until then, the info can be useful in case of
268 * a bug, and the overall stats will be off a bit only temporarily.
269 * Also, migrate_misplaced_transhuge_page() can still fail the
270 * migration and then we want the old folio to retain the info. But
271 * in that case we also don't need to explicitly clear the info from
272 * the new page, which will be freed.
274 __set_bit(PAGE_EXT_OWNER, &new_ext->flags);
275 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &new_ext->flags);
276 page_ext_put(new_ext);
277 page_ext_put(old_ext);
280 void pagetypeinfo_showmixedcount_print(struct seq_file *m,
281 pg_data_t *pgdat, struct zone *zone)
284 struct page_ext *page_ext;
285 struct page_owner *page_owner;
286 unsigned long pfn, block_end_pfn;
287 unsigned long end_pfn = zone_end_pfn(zone);
288 unsigned long count[MIGRATE_TYPES] = { 0, };
289 int pageblock_mt, page_mt;
292 /* Scan block by block. First and last block may be incomplete */
293 pfn = zone->zone_start_pfn;
296 * Walk the zone in pageblock_nr_pages steps. If a page block spans
297 * a zone boundary, it will be double counted between zones. This does
298 * not matter as the mixed block count will still be correct
300 for (; pfn < end_pfn; ) {
301 page = pfn_to_online_page(pfn);
303 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
307 block_end_pfn = pageblock_end_pfn(pfn);
308 block_end_pfn = min(block_end_pfn, end_pfn);
310 pageblock_mt = get_pageblock_migratetype(page);
312 for (; pfn < block_end_pfn; pfn++) {
313 /* The pageblock is online, no need to recheck. */
314 page = pfn_to_page(pfn);
316 if (page_zone(page) != zone)
319 if (PageBuddy(page)) {
320 unsigned long freepage_order;
322 freepage_order = buddy_order_unsafe(page);
323 if (freepage_order <= MAX_PAGE_ORDER)
324 pfn += (1UL << freepage_order) - 1;
328 if (PageReserved(page))
331 page_ext = page_ext_get(page);
332 if (unlikely(!page_ext))
335 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
336 goto ext_put_continue;
338 page_owner = get_page_owner(page_ext);
339 page_mt = gfp_migratetype(page_owner->gfp_mask);
340 if (pageblock_mt != page_mt) {
341 if (is_migrate_cma(pageblock_mt))
342 count[MIGRATE_MOVABLE]++;
344 count[pageblock_mt]++;
347 page_ext_put(page_ext);
350 pfn += (1UL << page_owner->order) - 1;
352 page_ext_put(page_ext);
357 seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
358 for (i = 0; i < MIGRATE_TYPES; i++)
359 seq_printf(m, "%12lu ", count[i]);
364 * Looking for memcg information and print it out
366 static inline int print_page_owner_memcg(char *kbuf, size_t count, int ret,
370 unsigned long memcg_data;
371 struct mem_cgroup *memcg;
376 memcg_data = READ_ONCE(page->memcg_data);
380 if (memcg_data & MEMCG_DATA_OBJCGS)
381 ret += scnprintf(kbuf + ret, count - ret,
382 "Slab cache page\n");
384 memcg = page_memcg_check(page);
388 online = (memcg->css.flags & CSS_ONLINE);
389 cgroup_name(memcg->css.cgroup, name, sizeof(name));
390 ret += scnprintf(kbuf + ret, count - ret,
391 "Charged %sto %smemcg %s\n",
392 PageMemcgKmem(page) ? "(via objcg) " : "",
393 online ? "" : "offline ",
397 #endif /* CONFIG_MEMCG */
403 print_page_owner(char __user *buf, size_t count, unsigned long pfn,
404 struct page *page, struct page_owner *page_owner,
405 depot_stack_handle_t handle)
407 int ret, pageblock_mt, page_mt;
410 count = min_t(size_t, count, PAGE_SIZE);
411 kbuf = kmalloc(count, GFP_KERNEL);
415 ret = scnprintf(kbuf, count,
416 "Page allocated via order %u, mask %#x(%pGg), pid %d, tgid %d (%s), ts %llu ns\n",
417 page_owner->order, page_owner->gfp_mask,
418 &page_owner->gfp_mask, page_owner->pid,
419 page_owner->tgid, page_owner->comm,
420 page_owner->ts_nsec);
422 /* Print information relevant to grouping pages by mobility */
423 pageblock_mt = get_pageblock_migratetype(page);
424 page_mt = gfp_migratetype(page_owner->gfp_mask);
425 ret += scnprintf(kbuf + ret, count - ret,
426 "PFN 0x%lx type %s Block %lu type %s Flags %pGp\n",
428 migratetype_names[page_mt],
429 pfn >> pageblock_order,
430 migratetype_names[pageblock_mt],
433 ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0);
437 if (page_owner->last_migrate_reason != -1) {
438 ret += scnprintf(kbuf + ret, count - ret,
439 "Page has been migrated, last migrate reason: %s\n",
440 migrate_reason_names[page_owner->last_migrate_reason]);
443 ret = print_page_owner_memcg(kbuf, count, ret, page);
445 ret += snprintf(kbuf + ret, count - ret, "\n");
449 if (copy_to_user(buf, kbuf, ret))
460 void __dump_page_owner(const struct page *page)
462 struct page_ext *page_ext = page_ext_get((void *)page);
463 struct page_owner *page_owner;
464 depot_stack_handle_t handle;
468 if (unlikely(!page_ext)) {
469 pr_alert("There is not page extension available.\n");
473 page_owner = get_page_owner(page_ext);
474 gfp_mask = page_owner->gfp_mask;
475 mt = gfp_migratetype(gfp_mask);
477 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
478 pr_alert("page_owner info is not present (never set?)\n");
479 page_ext_put(page_ext);
483 if (test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
484 pr_alert("page_owner tracks the page as allocated\n");
486 pr_alert("page_owner tracks the page as freed\n");
488 pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg), pid %d, tgid %d (%s), ts %llu, free_ts %llu\n",
489 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask,
490 page_owner->pid, page_owner->tgid, page_owner->comm,
491 page_owner->ts_nsec, page_owner->free_ts_nsec);
493 handle = READ_ONCE(page_owner->handle);
495 pr_alert("page_owner allocation stack trace missing\n");
497 stack_depot_print(handle);
499 handle = READ_ONCE(page_owner->free_handle);
501 pr_alert("page_owner free stack trace missing\n");
503 pr_alert("page last free pid %d tgid %d stack trace:\n",
504 page_owner->free_pid, page_owner->free_tgid);
505 stack_depot_print(handle);
508 if (page_owner->last_migrate_reason != -1)
509 pr_alert("page has been migrated, last migrate reason: %s\n",
510 migrate_reason_names[page_owner->last_migrate_reason]);
511 page_ext_put(page_ext);
515 read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
519 struct page_ext *page_ext;
520 struct page_owner *page_owner;
521 depot_stack_handle_t handle;
523 if (!static_branch_unlikely(&page_owner_inited))
531 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
532 while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
535 /* Find an allocated page */
536 for (; pfn < max_pfn; pfn++) {
538 * This temporary page_owner is required so
539 * that we can avoid the context switches while holding
540 * the rcu lock and copying the page owner information to
541 * user through copy_to_user() or GFP_KERNEL allocations.
543 struct page_owner page_owner_tmp;
546 * If the new page is in a new MAX_ORDER_NR_PAGES area,
547 * validate the area as existing, skip it if not
549 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
550 pfn += MAX_ORDER_NR_PAGES - 1;
554 page = pfn_to_page(pfn);
555 if (PageBuddy(page)) {
556 unsigned long freepage_order = buddy_order_unsafe(page);
558 if (freepage_order <= MAX_PAGE_ORDER)
559 pfn += (1UL << freepage_order) - 1;
563 page_ext = page_ext_get(page);
564 if (unlikely(!page_ext))
568 * Some pages could be missed by concurrent allocation or free,
569 * because we don't hold the zone lock.
571 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
572 goto ext_put_continue;
575 * Although we do have the info about past allocation of free
576 * pages, it's not relevant for current memory usage.
578 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
579 goto ext_put_continue;
581 page_owner = get_page_owner(page_ext);
584 * Don't print "tail" pages of high-order allocations as that
585 * would inflate the stats.
587 if (!IS_ALIGNED(pfn, 1 << page_owner->order))
588 goto ext_put_continue;
591 * Access to page_ext->handle isn't synchronous so we should
592 * be careful to access it.
594 handle = READ_ONCE(page_owner->handle);
596 goto ext_put_continue;
598 /* Record the next PFN to read in the file offset */
601 page_owner_tmp = *page_owner;
602 page_ext_put(page_ext);
603 return print_page_owner(buf, count, pfn, page,
604 &page_owner_tmp, handle);
606 page_ext_put(page_ext);
612 static loff_t lseek_page_owner(struct file *file, loff_t offset, int orig)
616 file->f_pos = offset;
619 file->f_pos += offset;
627 static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
629 unsigned long pfn = zone->zone_start_pfn;
630 unsigned long end_pfn = zone_end_pfn(zone);
631 unsigned long count = 0;
634 * Walk the zone in pageblock_nr_pages steps. If a page block spans
635 * a zone boundary, it will be double counted between zones. This does
636 * not matter as the mixed block count will still be correct
638 for (; pfn < end_pfn; ) {
639 unsigned long block_end_pfn;
641 if (!pfn_valid(pfn)) {
642 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
646 block_end_pfn = pageblock_end_pfn(pfn);
647 block_end_pfn = min(block_end_pfn, end_pfn);
649 for (; pfn < block_end_pfn; pfn++) {
650 struct page *page = pfn_to_page(pfn);
651 struct page_ext *page_ext;
653 if (page_zone(page) != zone)
657 * To avoid having to grab zone->lock, be a little
658 * careful when reading buddy page order. The only
659 * danger is that we skip too much and potentially miss
660 * some early allocated pages, which is better than
661 * heavy lock contention.
663 if (PageBuddy(page)) {
664 unsigned long order = buddy_order_unsafe(page);
666 if (order > 0 && order <= MAX_PAGE_ORDER)
667 pfn += (1UL << order) - 1;
671 if (PageReserved(page))
674 page_ext = page_ext_get(page);
675 if (unlikely(!page_ext))
678 /* Maybe overlapping zone */
679 if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
680 goto ext_put_continue;
682 /* Found early allocated page */
683 __set_page_owner_handle(page_ext, early_handle,
687 page_ext_put(page_ext);
692 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
693 pgdat->node_id, zone->name, count);
696 static void init_zones_in_node(pg_data_t *pgdat)
699 struct zone *node_zones = pgdat->node_zones;
701 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
702 if (!populated_zone(zone))
705 init_pages_in_zone(pgdat, zone);
709 static void init_early_allocated_pages(void)
713 for_each_online_pgdat(pgdat)
714 init_zones_in_node(pgdat);
717 static const struct file_operations proc_page_owner_operations = {
718 .read = read_page_owner,
719 .llseek = lseek_page_owner,
722 static int __init pageowner_init(void)
724 if (!static_branch_unlikely(&page_owner_inited)) {
725 pr_info("page_owner is disabled\n");
729 debugfs_create_file("page_owner", 0400, NULL, NULL,
730 &proc_page_owner_operations);
734 late_initcall(pageowner_init)