1 #include <linux/debugfs.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>
16 * TODO: teach PAGE_OWNER_STACK_DEPTH (__dump_page_owner and save_stack)
17 * to use off stack temporal storage
19 #define PAGE_OWNER_STACK_DEPTH (16)
21 static bool page_owner_disabled = true;
22 DEFINE_STATIC_KEY_FALSE(page_owner_inited);
24 static depot_stack_handle_t dummy_handle;
25 static depot_stack_handle_t failure_handle;
27 static void init_early_allocated_pages(void);
29 static int early_page_owner_param(char *buf)
34 if (strcmp(buf, "on") == 0)
35 page_owner_disabled = false;
39 early_param("page_owner", early_page_owner_param);
41 static bool need_page_owner(void)
43 if (page_owner_disabled)
49 static noinline void register_dummy_stack(void)
51 unsigned long entries[4];
52 struct stack_trace dummy;
55 dummy.max_entries = ARRAY_SIZE(entries);
56 dummy.entries = &entries[0];
59 save_stack_trace(&dummy);
60 dummy_handle = depot_save_stack(&dummy, GFP_KERNEL);
63 static noinline void register_failure_stack(void)
65 unsigned long entries[4];
66 struct stack_trace failure;
68 failure.nr_entries = 0;
69 failure.max_entries = ARRAY_SIZE(entries);
70 failure.entries = &entries[0];
73 save_stack_trace(&failure);
74 failure_handle = depot_save_stack(&failure, GFP_KERNEL);
77 static void init_page_owner(void)
79 if (page_owner_disabled)
82 register_dummy_stack();
83 register_failure_stack();
84 static_branch_enable(&page_owner_inited);
85 init_early_allocated_pages();
88 struct page_ext_operations page_owner_ops = {
89 .need = need_page_owner,
90 .init = init_page_owner,
93 void __reset_page_owner(struct page *page, unsigned int order)
96 struct page_ext *page_ext;
98 for (i = 0; i < (1 << order); i++) {
99 page_ext = lookup_page_ext(page + i);
100 if (unlikely(!page_ext))
102 __clear_bit(PAGE_EXT_OWNER, &page_ext->flags);
106 static inline bool check_recursive_alloc(struct stack_trace *trace,
111 if (!trace->nr_entries)
114 for (i = 0, count = 0; i < trace->nr_entries; i++) {
115 if (trace->entries[i] == ip && ++count == 2)
122 static noinline depot_stack_handle_t save_stack(gfp_t flags)
124 unsigned long entries[PAGE_OWNER_STACK_DEPTH];
125 struct stack_trace trace = {
128 .max_entries = PAGE_OWNER_STACK_DEPTH,
131 depot_stack_handle_t handle;
133 save_stack_trace(&trace);
134 if (trace.nr_entries != 0 &&
135 trace.entries[trace.nr_entries-1] == ULONG_MAX)
139 * We need to check recursion here because our request to stackdepot
140 * could trigger memory allocation to save new entry. New memory
141 * allocation would reach here and call depot_save_stack() again
142 * if we don't catch it. There is still not enough memory in stackdepot
143 * so it would try to allocate memory again and loop forever.
145 if (check_recursive_alloc(&trace, _RET_IP_))
148 handle = depot_save_stack(&trace, flags);
150 handle = failure_handle;
155 noinline void __set_page_owner(struct page *page, unsigned int order,
158 struct page_ext *page_ext = lookup_page_ext(page);
160 if (unlikely(!page_ext))
163 page_ext->handle = save_stack(gfp_mask);
164 page_ext->order = order;
165 page_ext->gfp_mask = gfp_mask;
166 page_ext->last_migrate_reason = -1;
168 __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
171 void __set_page_owner_migrate_reason(struct page *page, int reason)
173 struct page_ext *page_ext = lookup_page_ext(page);
174 if (unlikely(!page_ext))
177 page_ext->last_migrate_reason = reason;
180 void __split_page_owner(struct page *page, unsigned int order)
183 struct page_ext *page_ext = lookup_page_ext(page);
185 if (unlikely(!page_ext))
189 for (i = 1; i < (1 << order); i++)
190 __copy_page_owner(page, page + i);
193 void __copy_page_owner(struct page *oldpage, struct page *newpage)
195 struct page_ext *old_ext = lookup_page_ext(oldpage);
196 struct page_ext *new_ext = lookup_page_ext(newpage);
198 if (unlikely(!old_ext || !new_ext))
201 new_ext->order = old_ext->order;
202 new_ext->gfp_mask = old_ext->gfp_mask;
203 new_ext->last_migrate_reason = old_ext->last_migrate_reason;
204 new_ext->handle = old_ext->handle;
207 * We don't clear the bit on the oldpage as it's going to be freed
208 * after migration. Until then, the info can be useful in case of
209 * a bug, and the overal stats will be off a bit only temporarily.
210 * Also, migrate_misplaced_transhuge_page() can still fail the
211 * migration and then we want the oldpage to retain the info. But
212 * in that case we also don't need to explicitly clear the info from
213 * the new page, which will be freed.
215 __set_bit(PAGE_EXT_OWNER, &new_ext->flags);
218 void pagetypeinfo_showmixedcount_print(struct seq_file *m,
219 pg_data_t *pgdat, struct zone *zone)
222 struct page_ext *page_ext;
223 unsigned long pfn = zone->zone_start_pfn, block_end_pfn;
224 unsigned long end_pfn = pfn + zone->spanned_pages;
225 unsigned long count[MIGRATE_TYPES] = { 0, };
226 int pageblock_mt, page_mt;
229 /* Scan block by block. First and last block may be incomplete */
230 pfn = zone->zone_start_pfn;
233 * Walk the zone in pageblock_nr_pages steps. If a page block spans
234 * a zone boundary, it will be double counted between zones. This does
235 * not matter as the mixed block count will still be correct
237 for (; pfn < end_pfn; ) {
238 if (!pfn_valid(pfn)) {
239 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
243 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
244 block_end_pfn = min(block_end_pfn, end_pfn);
246 page = pfn_to_page(pfn);
247 pageblock_mt = get_pageblock_migratetype(page);
249 for (; pfn < block_end_pfn; pfn++) {
250 if (!pfn_valid_within(pfn))
253 page = pfn_to_page(pfn);
255 if (page_zone(page) != zone)
258 if (PageBuddy(page)) {
259 pfn += (1UL << page_order(page)) - 1;
263 if (PageReserved(page))
266 page_ext = lookup_page_ext(page);
267 if (unlikely(!page_ext))
270 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
273 page_mt = gfpflags_to_migratetype(page_ext->gfp_mask);
274 if (pageblock_mt != page_mt) {
275 if (is_migrate_cma(pageblock_mt))
276 count[MIGRATE_MOVABLE]++;
278 count[pageblock_mt]++;
283 pfn += (1UL << page_ext->order) - 1;
288 seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
289 for (i = 0; i < MIGRATE_TYPES; i++)
290 seq_printf(m, "%12lu ", count[i]);
295 print_page_owner(char __user *buf, size_t count, unsigned long pfn,
296 struct page *page, struct page_ext *page_ext,
297 depot_stack_handle_t handle)
300 int pageblock_mt, page_mt;
302 unsigned long entries[PAGE_OWNER_STACK_DEPTH];
303 struct stack_trace trace = {
306 .max_entries = PAGE_OWNER_STACK_DEPTH,
310 kbuf = kmalloc(count, GFP_KERNEL);
314 ret = snprintf(kbuf, count,
315 "Page allocated via order %u, mask %#x(%pGg)\n",
316 page_ext->order, page_ext->gfp_mask,
317 &page_ext->gfp_mask);
322 /* Print information relevant to grouping pages by mobility */
323 pageblock_mt = get_pageblock_migratetype(page);
324 page_mt = gfpflags_to_migratetype(page_ext->gfp_mask);
325 ret += snprintf(kbuf + ret, count - ret,
326 "PFN %lu type %s Block %lu type %s Flags %#lx(%pGp)\n",
328 migratetype_names[page_mt],
329 pfn >> pageblock_order,
330 migratetype_names[pageblock_mt],
331 page->flags, &page->flags);
336 depot_fetch_stack(handle, &trace);
337 ret += snprint_stack_trace(kbuf + ret, count - ret, &trace, 0);
341 if (page_ext->last_migrate_reason != -1) {
342 ret += snprintf(kbuf + ret, count - ret,
343 "Page has been migrated, last migrate reason: %s\n",
344 migrate_reason_names[page_ext->last_migrate_reason]);
349 ret += snprintf(kbuf + ret, count - ret, "\n");
353 if (copy_to_user(buf, kbuf, ret))
364 void __dump_page_owner(struct page *page)
366 struct page_ext *page_ext = lookup_page_ext(page);
367 unsigned long entries[PAGE_OWNER_STACK_DEPTH];
368 struct stack_trace trace = {
371 .max_entries = PAGE_OWNER_STACK_DEPTH,
374 depot_stack_handle_t handle;
378 if (unlikely(!page_ext)) {
379 pr_alert("There is not page extension available.\n");
382 gfp_mask = page_ext->gfp_mask;
383 mt = gfpflags_to_migratetype(gfp_mask);
385 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
386 pr_alert("page_owner info is not active (free page?)\n");
390 handle = READ_ONCE(page_ext->handle);
392 pr_alert("page_owner info is not active (free page?)\n");
396 depot_fetch_stack(handle, &trace);
397 pr_alert("page allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n",
398 page_ext->order, migratetype_names[mt], gfp_mask, &gfp_mask);
399 print_stack_trace(&trace, 0);
401 if (page_ext->last_migrate_reason != -1)
402 pr_alert("page has been migrated, last migrate reason: %s\n",
403 migrate_reason_names[page_ext->last_migrate_reason]);
407 read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
411 struct page_ext *page_ext;
412 depot_stack_handle_t handle;
414 if (!static_branch_unlikely(&page_owner_inited))
418 pfn = min_low_pfn + *ppos;
420 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
421 while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
424 drain_all_pages(NULL);
426 /* Find an allocated page */
427 for (; pfn < max_pfn; pfn++) {
429 * If the new page is in a new MAX_ORDER_NR_PAGES area,
430 * validate the area as existing, skip it if not
432 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
433 pfn += MAX_ORDER_NR_PAGES - 1;
437 /* Check for holes within a MAX_ORDER area */
438 if (!pfn_valid_within(pfn))
441 page = pfn_to_page(pfn);
442 if (PageBuddy(page)) {
443 unsigned long freepage_order = page_order_unsafe(page);
445 if (freepage_order < MAX_ORDER)
446 pfn += (1UL << freepage_order) - 1;
450 page_ext = lookup_page_ext(page);
451 if (unlikely(!page_ext))
455 * Some pages could be missed by concurrent allocation or free,
456 * because we don't hold the zone lock.
458 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
462 * Access to page_ext->handle isn't synchronous so we should
463 * be careful to access it.
465 handle = READ_ONCE(page_ext->handle);
469 /* Record the next PFN to read in the file offset */
470 *ppos = (pfn - min_low_pfn) + 1;
472 return print_page_owner(buf, count, pfn, page,
479 static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
482 struct page_ext *page_ext;
483 unsigned long pfn = zone->zone_start_pfn, block_end_pfn;
484 unsigned long end_pfn = pfn + zone->spanned_pages;
485 unsigned long count = 0;
487 /* Scan block by block. First and last block may be incomplete */
488 pfn = zone->zone_start_pfn;
491 * Walk the zone in pageblock_nr_pages steps. If a page block spans
492 * a zone boundary, it will be double counted between zones. This does
493 * not matter as the mixed block count will still be correct
495 for (; pfn < end_pfn; ) {
496 if (!pfn_valid(pfn)) {
497 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
501 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
502 block_end_pfn = min(block_end_pfn, end_pfn);
504 page = pfn_to_page(pfn);
506 for (; pfn < block_end_pfn; pfn++) {
507 if (!pfn_valid_within(pfn))
510 page = pfn_to_page(pfn);
512 if (page_zone(page) != zone)
516 * We are safe to check buddy flag and order, because
517 * this is init stage and only single thread runs.
519 if (PageBuddy(page)) {
520 pfn += (1UL << page_order(page)) - 1;
524 if (PageReserved(page))
527 page_ext = lookup_page_ext(page);
528 if (unlikely(!page_ext))
531 /* Maybe overraping zone */
532 if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
535 /* Found early allocated page */
536 set_page_owner(page, 0, 0);
541 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
542 pgdat->node_id, zone->name, count);
545 static void init_zones_in_node(pg_data_t *pgdat)
548 struct zone *node_zones = pgdat->node_zones;
551 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
552 if (!populated_zone(zone))
555 spin_lock_irqsave(&zone->lock, flags);
556 init_pages_in_zone(pgdat, zone);
557 spin_unlock_irqrestore(&zone->lock, flags);
561 static void init_early_allocated_pages(void)
565 drain_all_pages(NULL);
566 for_each_online_pgdat(pgdat)
567 init_zones_in_node(pgdat);
570 static const struct file_operations proc_page_owner_operations = {
571 .read = read_page_owner,
574 static int __init pageowner_init(void)
576 struct dentry *dentry;
578 if (!static_branch_unlikely(&page_owner_inited)) {
579 pr_info("page_owner is disabled\n");
583 dentry = debugfs_create_file("page_owner", S_IRUSR, NULL,
584 NULL, &proc_page_owner_operations);
586 return PTR_ERR(dentry);
590 late_initcall(pageowner_init)