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/sched/clock.h>
18 * TODO: teach PAGE_OWNER_STACK_DEPTH (__dump_page_owner and save_stack)
19 * to use off stack temporal storage
21 #define PAGE_OWNER_STACK_DEPTH (16)
25 short last_migrate_reason;
27 depot_stack_handle_t handle;
28 depot_stack_handle_t free_handle;
34 static bool page_owner_enabled = false;
35 DEFINE_STATIC_KEY_FALSE(page_owner_inited);
37 static depot_stack_handle_t dummy_handle;
38 static depot_stack_handle_t failure_handle;
39 static depot_stack_handle_t early_handle;
41 static void init_early_allocated_pages(void);
43 static int __init early_page_owner_param(char *buf)
45 return kstrtobool(buf, &page_owner_enabled);
47 early_param("page_owner", early_page_owner_param);
49 static __init bool need_page_owner(void)
51 return page_owner_enabled;
54 static __always_inline depot_stack_handle_t create_dummy_stack(void)
56 unsigned long entries[4];
57 unsigned int nr_entries;
59 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
60 return stack_depot_save(entries, nr_entries, GFP_KERNEL);
63 static noinline void register_dummy_stack(void)
65 dummy_handle = create_dummy_stack();
68 static noinline void register_failure_stack(void)
70 failure_handle = create_dummy_stack();
73 static noinline void register_early_stack(void)
75 early_handle = create_dummy_stack();
78 static __init void init_page_owner(void)
80 if (!page_owner_enabled)
83 register_dummy_stack();
84 register_failure_stack();
85 register_early_stack();
86 static_branch_enable(&page_owner_inited);
87 init_early_allocated_pages();
90 struct page_ext_operations page_owner_ops = {
91 .size = sizeof(struct page_owner),
92 .need = need_page_owner,
93 .init = init_page_owner,
96 static inline struct page_owner *get_page_owner(struct page_ext *page_ext)
98 return (void *)page_ext + page_owner_ops.offset;
101 static noinline depot_stack_handle_t save_stack(gfp_t flags)
103 unsigned long entries[PAGE_OWNER_STACK_DEPTH];
104 depot_stack_handle_t handle;
105 unsigned int nr_entries;
110 * Sometimes page metadata allocation tracking requires more
111 * memory to be allocated:
112 * - when new stack trace is saved to stack depot
113 * - when backtrace itself is calculated (ia64)
115 if (current->in_page_owner)
117 current->in_page_owner = 1;
119 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2);
120 handle = stack_depot_save(entries, nr_entries, flags);
122 handle = failure_handle;
124 current->in_page_owner = 0;
128 void __reset_page_owner(struct page *page, unsigned short order)
131 struct page_ext *page_ext;
132 depot_stack_handle_t handle;
133 struct page_owner *page_owner;
134 u64 free_ts_nsec = local_clock();
136 page_ext = lookup_page_ext(page);
137 if (unlikely(!page_ext))
140 handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
141 for (i = 0; i < (1 << order); i++) {
142 __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
143 page_owner = get_page_owner(page_ext);
144 page_owner->free_handle = handle;
145 page_owner->free_ts_nsec = free_ts_nsec;
146 page_ext = page_ext_next(page_ext);
150 static inline void __set_page_owner_handle(struct page_ext *page_ext,
151 depot_stack_handle_t handle,
152 unsigned short order, gfp_t gfp_mask)
154 struct page_owner *page_owner;
157 for (i = 0; i < (1 << order); i++) {
158 page_owner = get_page_owner(page_ext);
159 page_owner->handle = handle;
160 page_owner->order = order;
161 page_owner->gfp_mask = gfp_mask;
162 page_owner->last_migrate_reason = -1;
163 page_owner->pid = current->pid;
164 page_owner->ts_nsec = local_clock();
165 __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
166 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
168 page_ext = page_ext_next(page_ext);
172 noinline void __set_page_owner(struct page *page, unsigned short order,
175 struct page_ext *page_ext = lookup_page_ext(page);
176 depot_stack_handle_t handle;
178 if (unlikely(!page_ext))
181 handle = save_stack(gfp_mask);
182 __set_page_owner_handle(page_ext, handle, order, gfp_mask);
185 void __set_page_owner_migrate_reason(struct page *page, int reason)
187 struct page_ext *page_ext = lookup_page_ext(page);
188 struct page_owner *page_owner;
190 if (unlikely(!page_ext))
193 page_owner = get_page_owner(page_ext);
194 page_owner->last_migrate_reason = reason;
197 void __split_page_owner(struct page *page, unsigned int nr)
200 struct page_ext *page_ext = lookup_page_ext(page);
201 struct page_owner *page_owner;
203 if (unlikely(!page_ext))
206 for (i = 0; i < nr; i++) {
207 page_owner = get_page_owner(page_ext);
208 page_owner->order = 0;
209 page_ext = page_ext_next(page_ext);
213 void __folio_copy_owner(struct folio *newfolio, struct folio *old)
215 struct page_ext *old_ext = lookup_page_ext(&old->page);
216 struct page_ext *new_ext = lookup_page_ext(&newfolio->page);
217 struct page_owner *old_page_owner, *new_page_owner;
219 if (unlikely(!old_ext || !new_ext))
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 new_page_owner->pid = old_page_owner->pid;
230 new_page_owner->ts_nsec = old_page_owner->ts_nsec;
231 new_page_owner->free_ts_nsec = old_page_owner->ts_nsec;
234 * We don't clear the bit on the old folio as it's going to be freed
235 * after migration. Until then, the info can be useful in case of
236 * a bug, and the overall stats will be off a bit only temporarily.
237 * Also, migrate_misplaced_transhuge_page() can still fail the
238 * migration and then we want the old folio to retain the info. But
239 * in that case we also don't need to explicitly clear the info from
240 * the new page, which will be freed.
242 __set_bit(PAGE_EXT_OWNER, &new_ext->flags);
243 __set_bit(PAGE_EXT_OWNER_ALLOCATED, &new_ext->flags);
246 void pagetypeinfo_showmixedcount_print(struct seq_file *m,
247 pg_data_t *pgdat, struct zone *zone)
250 struct page_ext *page_ext;
251 struct page_owner *page_owner;
252 unsigned long pfn, block_end_pfn;
253 unsigned long end_pfn = zone_end_pfn(zone);
254 unsigned long count[MIGRATE_TYPES] = { 0, };
255 int pageblock_mt, page_mt;
258 /* Scan block by block. First and last block may be incomplete */
259 pfn = zone->zone_start_pfn;
262 * Walk the zone in pageblock_nr_pages steps. If a page block spans
263 * a zone boundary, it will be double counted between zones. This does
264 * not matter as the mixed block count will still be correct
266 for (; pfn < end_pfn; ) {
267 page = pfn_to_online_page(pfn);
269 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
273 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
274 block_end_pfn = min(block_end_pfn, end_pfn);
276 pageblock_mt = get_pageblock_migratetype(page);
278 for (; pfn < block_end_pfn; pfn++) {
279 /* The pageblock is online, no need to recheck. */
280 page = pfn_to_page(pfn);
282 if (page_zone(page) != zone)
285 if (PageBuddy(page)) {
286 unsigned long freepage_order;
288 freepage_order = buddy_order_unsafe(page);
289 if (freepage_order < MAX_ORDER)
290 pfn += (1UL << freepage_order) - 1;
294 if (PageReserved(page))
297 page_ext = lookup_page_ext(page);
298 if (unlikely(!page_ext))
301 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
304 page_owner = get_page_owner(page_ext);
305 page_mt = gfp_migratetype(page_owner->gfp_mask);
306 if (pageblock_mt != page_mt) {
307 if (is_migrate_cma(pageblock_mt))
308 count[MIGRATE_MOVABLE]++;
310 count[pageblock_mt]++;
315 pfn += (1UL << page_owner->order) - 1;
320 seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
321 for (i = 0; i < MIGRATE_TYPES; i++)
322 seq_printf(m, "%12lu ", count[i]);
327 print_page_owner(char __user *buf, size_t count, unsigned long pfn,
328 struct page *page, struct page_owner *page_owner,
329 depot_stack_handle_t handle)
331 int ret, pageblock_mt, page_mt;
334 count = min_t(size_t, count, PAGE_SIZE);
335 kbuf = kmalloc(count, GFP_KERNEL);
339 ret = snprintf(kbuf, count,
340 "Page allocated via order %u, mask %#x(%pGg), pid %d, ts %llu ns, free_ts %llu ns\n",
341 page_owner->order, page_owner->gfp_mask,
342 &page_owner->gfp_mask, page_owner->pid,
343 page_owner->ts_nsec, page_owner->free_ts_nsec);
348 /* Print information relevant to grouping pages by mobility */
349 pageblock_mt = get_pageblock_migratetype(page);
350 page_mt = gfp_migratetype(page_owner->gfp_mask);
351 ret += snprintf(kbuf + ret, count - ret,
352 "PFN %lu type %s Block %lu type %s Flags %pGp\n",
354 migratetype_names[page_mt],
355 pfn >> pageblock_order,
356 migratetype_names[pageblock_mt],
362 ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0);
366 if (page_owner->last_migrate_reason != -1) {
367 ret += snprintf(kbuf + ret, count - ret,
368 "Page has been migrated, last migrate reason: %s\n",
369 migrate_reason_names[page_owner->last_migrate_reason]);
374 ret += snprintf(kbuf + ret, count - ret, "\n");
378 if (copy_to_user(buf, kbuf, ret))
389 void __dump_page_owner(const struct page *page)
391 struct page_ext *page_ext = lookup_page_ext(page);
392 struct page_owner *page_owner;
393 depot_stack_handle_t handle;
397 if (unlikely(!page_ext)) {
398 pr_alert("There is not page extension available.\n");
402 page_owner = get_page_owner(page_ext);
403 gfp_mask = page_owner->gfp_mask;
404 mt = gfp_migratetype(gfp_mask);
406 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
407 pr_alert("page_owner info is not present (never set?)\n");
411 if (test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
412 pr_alert("page_owner tracks the page as allocated\n");
414 pr_alert("page_owner tracks the page as freed\n");
416 pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg), pid %d, ts %llu, free_ts %llu\n",
417 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask,
418 page_owner->pid, page_owner->ts_nsec, page_owner->free_ts_nsec);
420 handle = READ_ONCE(page_owner->handle);
422 pr_alert("page_owner allocation stack trace missing\n");
424 stack_depot_print(handle);
426 handle = READ_ONCE(page_owner->free_handle);
428 pr_alert("page_owner free stack trace missing\n");
430 pr_alert("page last free stack trace:\n");
431 stack_depot_print(handle);
434 if (page_owner->last_migrate_reason != -1)
435 pr_alert("page has been migrated, last migrate reason: %s\n",
436 migrate_reason_names[page_owner->last_migrate_reason]);
440 read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
444 struct page_ext *page_ext;
445 struct page_owner *page_owner;
446 depot_stack_handle_t handle;
448 if (!static_branch_unlikely(&page_owner_inited))
452 pfn = min_low_pfn + *ppos;
454 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
455 while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
458 drain_all_pages(NULL);
460 /* Find an allocated page */
461 for (; pfn < max_pfn; pfn++) {
463 * If the new page is in a new MAX_ORDER_NR_PAGES area,
464 * validate the area as existing, skip it if not
466 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
467 pfn += MAX_ORDER_NR_PAGES - 1;
471 page = pfn_to_page(pfn);
472 if (PageBuddy(page)) {
473 unsigned long freepage_order = buddy_order_unsafe(page);
475 if (freepage_order < MAX_ORDER)
476 pfn += (1UL << freepage_order) - 1;
480 page_ext = lookup_page_ext(page);
481 if (unlikely(!page_ext))
485 * Some pages could be missed by concurrent allocation or free,
486 * because we don't hold the zone lock.
488 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
492 * Although we do have the info about past allocation of free
493 * pages, it's not relevant for current memory usage.
495 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
498 page_owner = get_page_owner(page_ext);
501 * Don't print "tail" pages of high-order allocations as that
502 * would inflate the stats.
504 if (!IS_ALIGNED(pfn, 1 << page_owner->order))
508 * Access to page_ext->handle isn't synchronous so we should
509 * be careful to access it.
511 handle = READ_ONCE(page_owner->handle);
515 /* Record the next PFN to read in the file offset */
516 *ppos = (pfn - min_low_pfn) + 1;
518 return print_page_owner(buf, count, pfn, page,
525 static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
527 unsigned long pfn = zone->zone_start_pfn;
528 unsigned long end_pfn = zone_end_pfn(zone);
529 unsigned long count = 0;
532 * Walk the zone in pageblock_nr_pages steps. If a page block spans
533 * a zone boundary, it will be double counted between zones. This does
534 * not matter as the mixed block count will still be correct
536 for (; pfn < end_pfn; ) {
537 unsigned long block_end_pfn;
539 if (!pfn_valid(pfn)) {
540 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
544 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
545 block_end_pfn = min(block_end_pfn, end_pfn);
547 for (; pfn < block_end_pfn; pfn++) {
548 struct page *page = pfn_to_page(pfn);
549 struct page_ext *page_ext;
551 if (page_zone(page) != zone)
555 * To avoid having to grab zone->lock, be a little
556 * careful when reading buddy page order. The only
557 * danger is that we skip too much and potentially miss
558 * some early allocated pages, which is better than
559 * heavy lock contention.
561 if (PageBuddy(page)) {
562 unsigned long order = buddy_order_unsafe(page);
564 if (order > 0 && order < MAX_ORDER)
565 pfn += (1UL << order) - 1;
569 if (PageReserved(page))
572 page_ext = lookup_page_ext(page);
573 if (unlikely(!page_ext))
576 /* Maybe overlapping zone */
577 if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
580 /* Found early allocated page */
581 __set_page_owner_handle(page_ext, early_handle,
588 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
589 pgdat->node_id, zone->name, count);
592 static void init_zones_in_node(pg_data_t *pgdat)
595 struct zone *node_zones = pgdat->node_zones;
597 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
598 if (!populated_zone(zone))
601 init_pages_in_zone(pgdat, zone);
605 static void init_early_allocated_pages(void)
609 for_each_online_pgdat(pgdat)
610 init_zones_in_node(pgdat);
613 static const struct file_operations proc_page_owner_operations = {
614 .read = read_page_owner,
617 static int __init pageowner_init(void)
619 if (!static_branch_unlikely(&page_owner_inited)) {
620 pr_info("page_owner is disabled\n");
624 debugfs_create_file("page_owner", 0400, NULL, NULL,
625 &proc_page_owner_operations);
629 late_initcall(pageowner_init)