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
];
37 static bool page_owner_enabled __initdata
;
38 DEFINE_STATIC_KEY_FALSE(page_owner_inited
);
40 static depot_stack_handle_t dummy_handle
;
41 static depot_stack_handle_t failure_handle
;
42 static depot_stack_handle_t early_handle
;
44 static void init_early_allocated_pages(void);
46 static int __init
early_page_owner_param(char *buf
)
48 int ret
= kstrtobool(buf
, &page_owner_enabled
);
50 if (page_owner_enabled
)
51 stack_depot_want_early_init();
55 early_param("page_owner", early_page_owner_param
);
57 static __init
bool need_page_owner(void)
59 return page_owner_enabled
;
62 static __always_inline depot_stack_handle_t
create_dummy_stack(void)
64 unsigned long entries
[4];
65 unsigned int nr_entries
;
67 nr_entries
= stack_trace_save(entries
, ARRAY_SIZE(entries
), 0);
68 return stack_depot_save(entries
, nr_entries
, GFP_KERNEL
);
71 static noinline
void register_dummy_stack(void)
73 dummy_handle
= create_dummy_stack();
76 static noinline
void register_failure_stack(void)
78 failure_handle
= create_dummy_stack();
81 static noinline
void register_early_stack(void)
83 early_handle
= create_dummy_stack();
86 static __init
void init_page_owner(void)
88 if (!page_owner_enabled
)
91 register_dummy_stack();
92 register_failure_stack();
93 register_early_stack();
94 static_branch_enable(&page_owner_inited
);
95 init_early_allocated_pages();
98 struct page_ext_operations page_owner_ops
= {
99 .size
= sizeof(struct page_owner
),
100 .need
= need_page_owner
,
101 .init
= init_page_owner
,
104 static inline struct page_owner
*get_page_owner(struct page_ext
*page_ext
)
106 return (void *)page_ext
+ page_owner_ops
.offset
;
109 static noinline depot_stack_handle_t
save_stack(gfp_t flags
)
111 unsigned long entries
[PAGE_OWNER_STACK_DEPTH
];
112 depot_stack_handle_t handle
;
113 unsigned int nr_entries
;
118 * Sometimes page metadata allocation tracking requires more
119 * memory to be allocated:
120 * - when new stack trace is saved to stack depot
121 * - when backtrace itself is calculated (ia64)
123 if (current
->in_page_owner
)
125 current
->in_page_owner
= 1;
127 nr_entries
= stack_trace_save(entries
, ARRAY_SIZE(entries
), 2);
128 handle
= stack_depot_save(entries
, nr_entries
, flags
);
130 handle
= failure_handle
;
132 current
->in_page_owner
= 0;
136 void __reset_page_owner(struct page
*page
, unsigned short order
)
139 struct page_ext
*page_ext
;
140 depot_stack_handle_t handle
;
141 struct page_owner
*page_owner
;
142 u64 free_ts_nsec
= local_clock();
144 page_ext
= lookup_page_ext(page
);
145 if (unlikely(!page_ext
))
148 handle
= save_stack(GFP_NOWAIT
| __GFP_NOWARN
);
149 for (i
= 0; i
< (1 << order
); i
++) {
150 __clear_bit(PAGE_EXT_OWNER_ALLOCATED
, &page_ext
->flags
);
151 page_owner
= get_page_owner(page_ext
);
152 page_owner
->free_handle
= handle
;
153 page_owner
->free_ts_nsec
= free_ts_nsec
;
154 page_ext
= page_ext_next(page_ext
);
158 static inline void __set_page_owner_handle(struct page_ext
*page_ext
,
159 depot_stack_handle_t handle
,
160 unsigned short order
, gfp_t gfp_mask
)
162 struct page_owner
*page_owner
;
165 for (i
= 0; i
< (1 << order
); i
++) {
166 page_owner
= get_page_owner(page_ext
);
167 page_owner
->handle
= handle
;
168 page_owner
->order
= order
;
169 page_owner
->gfp_mask
= gfp_mask
;
170 page_owner
->last_migrate_reason
= -1;
171 page_owner
->pid
= current
->pid
;
172 page_owner
->tgid
= current
->tgid
;
173 page_owner
->ts_nsec
= local_clock();
174 strscpy(page_owner
->comm
, current
->comm
,
175 sizeof(page_owner
->comm
));
176 __set_bit(PAGE_EXT_OWNER
, &page_ext
->flags
);
177 __set_bit(PAGE_EXT_OWNER_ALLOCATED
, &page_ext
->flags
);
179 page_ext
= page_ext_next(page_ext
);
183 noinline
void __set_page_owner(struct page
*page
, unsigned short order
,
186 struct page_ext
*page_ext
= lookup_page_ext(page
);
187 depot_stack_handle_t handle
;
189 if (unlikely(!page_ext
))
192 handle
= save_stack(gfp_mask
);
193 __set_page_owner_handle(page_ext
, handle
, order
, gfp_mask
);
196 void __set_page_owner_migrate_reason(struct page
*page
, int reason
)
198 struct page_ext
*page_ext
= lookup_page_ext(page
);
199 struct page_owner
*page_owner
;
201 if (unlikely(!page_ext
))
204 page_owner
= get_page_owner(page_ext
);
205 page_owner
->last_migrate_reason
= reason
;
208 void __split_page_owner(struct page
*page
, unsigned int nr
)
211 struct page_ext
*page_ext
= lookup_page_ext(page
);
212 struct page_owner
*page_owner
;
214 if (unlikely(!page_ext
))
217 for (i
= 0; i
< nr
; i
++) {
218 page_owner
= get_page_owner(page_ext
);
219 page_owner
->order
= 0;
220 page_ext
= page_ext_next(page_ext
);
224 void __folio_copy_owner(struct folio
*newfolio
, struct folio
*old
)
226 struct page_ext
*old_ext
= lookup_page_ext(&old
->page
);
227 struct page_ext
*new_ext
= lookup_page_ext(&newfolio
->page
);
228 struct page_owner
*old_page_owner
, *new_page_owner
;
230 if (unlikely(!old_ext
|| !new_ext
))
233 old_page_owner
= get_page_owner(old_ext
);
234 new_page_owner
= get_page_owner(new_ext
);
235 new_page_owner
->order
= old_page_owner
->order
;
236 new_page_owner
->gfp_mask
= old_page_owner
->gfp_mask
;
237 new_page_owner
->last_migrate_reason
=
238 old_page_owner
->last_migrate_reason
;
239 new_page_owner
->handle
= old_page_owner
->handle
;
240 new_page_owner
->pid
= old_page_owner
->pid
;
241 new_page_owner
->tgid
= old_page_owner
->tgid
;
242 new_page_owner
->ts_nsec
= old_page_owner
->ts_nsec
;
243 new_page_owner
->free_ts_nsec
= old_page_owner
->ts_nsec
;
244 strcpy(new_page_owner
->comm
, old_page_owner
->comm
);
247 * We don't clear the bit on the old folio as it's going to be freed
248 * after migration. Until then, the info can be useful in case of
249 * a bug, and the overall stats will be off a bit only temporarily.
250 * Also, migrate_misplaced_transhuge_page() can still fail the
251 * migration and then we want the old folio to retain the info. But
252 * in that case we also don't need to explicitly clear the info from
253 * the new page, which will be freed.
255 __set_bit(PAGE_EXT_OWNER
, &new_ext
->flags
);
256 __set_bit(PAGE_EXT_OWNER_ALLOCATED
, &new_ext
->flags
);
259 void pagetypeinfo_showmixedcount_print(struct seq_file
*m
,
260 pg_data_t
*pgdat
, struct zone
*zone
)
263 struct page_ext
*page_ext
;
264 struct page_owner
*page_owner
;
265 unsigned long pfn
, block_end_pfn
;
266 unsigned long end_pfn
= zone_end_pfn(zone
);
267 unsigned long count
[MIGRATE_TYPES
] = { 0, };
268 int pageblock_mt
, page_mt
;
271 /* Scan block by block. First and last block may be incomplete */
272 pfn
= zone
->zone_start_pfn
;
275 * Walk the zone in pageblock_nr_pages steps. If a page block spans
276 * a zone boundary, it will be double counted between zones. This does
277 * not matter as the mixed block count will still be correct
279 for (; pfn
< end_pfn
; ) {
280 page
= pfn_to_online_page(pfn
);
282 pfn
= ALIGN(pfn
+ 1, MAX_ORDER_NR_PAGES
);
286 block_end_pfn
= ALIGN(pfn
+ 1, pageblock_nr_pages
);
287 block_end_pfn
= min(block_end_pfn
, end_pfn
);
289 pageblock_mt
= get_pageblock_migratetype(page
);
291 for (; pfn
< block_end_pfn
; pfn
++) {
292 /* The pageblock is online, no need to recheck. */
293 page
= pfn_to_page(pfn
);
295 if (page_zone(page
) != zone
)
298 if (PageBuddy(page
)) {
299 unsigned long freepage_order
;
301 freepage_order
= buddy_order_unsafe(page
);
302 if (freepage_order
< MAX_ORDER
)
303 pfn
+= (1UL << freepage_order
) - 1;
307 if (PageReserved(page
))
310 page_ext
= lookup_page_ext(page
);
311 if (unlikely(!page_ext
))
314 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED
, &page_ext
->flags
))
317 page_owner
= get_page_owner(page_ext
);
318 page_mt
= gfp_migratetype(page_owner
->gfp_mask
);
319 if (pageblock_mt
!= page_mt
) {
320 if (is_migrate_cma(pageblock_mt
))
321 count
[MIGRATE_MOVABLE
]++;
323 count
[pageblock_mt
]++;
328 pfn
+= (1UL << page_owner
->order
) - 1;
333 seq_printf(m
, "Node %d, zone %8s ", pgdat
->node_id
, zone
->name
);
334 for (i
= 0; i
< MIGRATE_TYPES
; i
++)
335 seq_printf(m
, "%12lu ", count
[i
]);
340 * Looking for memcg information and print it out
342 static inline int print_page_owner_memcg(char *kbuf
, size_t count
, int ret
,
346 unsigned long memcg_data
;
347 struct mem_cgroup
*memcg
;
352 memcg_data
= READ_ONCE(page
->memcg_data
);
356 if (memcg_data
& MEMCG_DATA_OBJCGS
)
357 ret
+= scnprintf(kbuf
+ ret
, count
- ret
,
358 "Slab cache page\n");
360 memcg
= page_memcg_check(page
);
364 online
= (memcg
->css
.flags
& CSS_ONLINE
);
365 cgroup_name(memcg
->css
.cgroup
, name
, sizeof(name
));
366 ret
+= scnprintf(kbuf
+ ret
, count
- ret
,
367 "Charged %sto %smemcg %s\n",
368 PageMemcgKmem(page
) ? "(via objcg) " : "",
369 online
? "" : "offline ",
373 #endif /* CONFIG_MEMCG */
379 print_page_owner(char __user
*buf
, size_t count
, unsigned long pfn
,
380 struct page
*page
, struct page_owner
*page_owner
,
381 depot_stack_handle_t handle
)
383 int ret
, pageblock_mt
, page_mt
;
386 count
= min_t(size_t, count
, PAGE_SIZE
);
387 kbuf
= kmalloc(count
, GFP_KERNEL
);
391 ret
= scnprintf(kbuf
, count
,
392 "Page allocated via order %u, mask %#x(%pGg), pid %d, tgid %d (%s), ts %llu ns, free_ts %llu ns\n",
393 page_owner
->order
, page_owner
->gfp_mask
,
394 &page_owner
->gfp_mask
, page_owner
->pid
,
395 page_owner
->tgid
, page_owner
->comm
,
396 page_owner
->ts_nsec
, page_owner
->free_ts_nsec
);
398 /* Print information relevant to grouping pages by mobility */
399 pageblock_mt
= get_pageblock_migratetype(page
);
400 page_mt
= gfp_migratetype(page_owner
->gfp_mask
);
401 ret
+= scnprintf(kbuf
+ ret
, count
- ret
,
402 "PFN %lu type %s Block %lu type %s Flags %pGp\n",
404 migratetype_names
[page_mt
],
405 pfn
>> pageblock_order
,
406 migratetype_names
[pageblock_mt
],
409 ret
+= stack_depot_snprint(handle
, kbuf
+ ret
, count
- ret
, 0);
413 if (page_owner
->last_migrate_reason
!= -1) {
414 ret
+= scnprintf(kbuf
+ ret
, count
- ret
,
415 "Page has been migrated, last migrate reason: %s\n",
416 migrate_reason_names
[page_owner
->last_migrate_reason
]);
419 ret
= print_page_owner_memcg(kbuf
, count
, ret
, page
);
421 ret
+= snprintf(kbuf
+ ret
, count
- ret
, "\n");
425 if (copy_to_user(buf
, kbuf
, ret
))
436 void __dump_page_owner(const struct page
*page
)
438 struct page_ext
*page_ext
= lookup_page_ext(page
);
439 struct page_owner
*page_owner
;
440 depot_stack_handle_t handle
;
444 if (unlikely(!page_ext
)) {
445 pr_alert("There is not page extension available.\n");
449 page_owner
= get_page_owner(page_ext
);
450 gfp_mask
= page_owner
->gfp_mask
;
451 mt
= gfp_migratetype(gfp_mask
);
453 if (!test_bit(PAGE_EXT_OWNER
, &page_ext
->flags
)) {
454 pr_alert("page_owner info is not present (never set?)\n");
458 if (test_bit(PAGE_EXT_OWNER_ALLOCATED
, &page_ext
->flags
))
459 pr_alert("page_owner tracks the page as allocated\n");
461 pr_alert("page_owner tracks the page as freed\n");
463 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",
464 page_owner
->order
, migratetype_names
[mt
], gfp_mask
, &gfp_mask
,
465 page_owner
->pid
, page_owner
->tgid
, page_owner
->comm
,
466 page_owner
->ts_nsec
, page_owner
->free_ts_nsec
);
468 handle
= READ_ONCE(page_owner
->handle
);
470 pr_alert("page_owner allocation stack trace missing\n");
472 stack_depot_print(handle
);
474 handle
= READ_ONCE(page_owner
->free_handle
);
476 pr_alert("page_owner free stack trace missing\n");
478 pr_alert("page last free stack trace:\n");
479 stack_depot_print(handle
);
482 if (page_owner
->last_migrate_reason
!= -1)
483 pr_alert("page has been migrated, last migrate reason: %s\n",
484 migrate_reason_names
[page_owner
->last_migrate_reason
]);
488 read_page_owner(struct file
*file
, char __user
*buf
, size_t count
, loff_t
*ppos
)
492 struct page_ext
*page_ext
;
493 struct page_owner
*page_owner
;
494 depot_stack_handle_t handle
;
496 if (!static_branch_unlikely(&page_owner_inited
))
500 pfn
= min_low_pfn
+ *ppos
;
502 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
503 while (!pfn_valid(pfn
) && (pfn
& (MAX_ORDER_NR_PAGES
- 1)) != 0)
506 drain_all_pages(NULL
);
508 /* Find an allocated page */
509 for (; pfn
< max_pfn
; pfn
++) {
511 * If the new page is in a new MAX_ORDER_NR_PAGES area,
512 * validate the area as existing, skip it if not
514 if ((pfn
& (MAX_ORDER_NR_PAGES
- 1)) == 0 && !pfn_valid(pfn
)) {
515 pfn
+= MAX_ORDER_NR_PAGES
- 1;
519 page
= pfn_to_page(pfn
);
520 if (PageBuddy(page
)) {
521 unsigned long freepage_order
= buddy_order_unsafe(page
);
523 if (freepage_order
< MAX_ORDER
)
524 pfn
+= (1UL << freepage_order
) - 1;
528 page_ext
= lookup_page_ext(page
);
529 if (unlikely(!page_ext
))
533 * Some pages could be missed by concurrent allocation or free,
534 * because we don't hold the zone lock.
536 if (!test_bit(PAGE_EXT_OWNER
, &page_ext
->flags
))
540 * Although we do have the info about past allocation of free
541 * pages, it's not relevant for current memory usage.
543 if (!test_bit(PAGE_EXT_OWNER_ALLOCATED
, &page_ext
->flags
))
546 page_owner
= get_page_owner(page_ext
);
549 * Don't print "tail" pages of high-order allocations as that
550 * would inflate the stats.
552 if (!IS_ALIGNED(pfn
, 1 << page_owner
->order
))
556 * Access to page_ext->handle isn't synchronous so we should
557 * be careful to access it.
559 handle
= READ_ONCE(page_owner
->handle
);
563 /* Record the next PFN to read in the file offset */
564 *ppos
= (pfn
- min_low_pfn
) + 1;
566 return print_page_owner(buf
, count
, pfn
, page
,
573 static void init_pages_in_zone(pg_data_t
*pgdat
, struct zone
*zone
)
575 unsigned long pfn
= zone
->zone_start_pfn
;
576 unsigned long end_pfn
= zone_end_pfn(zone
);
577 unsigned long count
= 0;
580 * Walk the zone in pageblock_nr_pages steps. If a page block spans
581 * a zone boundary, it will be double counted between zones. This does
582 * not matter as the mixed block count will still be correct
584 for (; pfn
< end_pfn
; ) {
585 unsigned long block_end_pfn
;
587 if (!pfn_valid(pfn
)) {
588 pfn
= ALIGN(pfn
+ 1, MAX_ORDER_NR_PAGES
);
592 block_end_pfn
= ALIGN(pfn
+ 1, pageblock_nr_pages
);
593 block_end_pfn
= min(block_end_pfn
, end_pfn
);
595 for (; pfn
< block_end_pfn
; pfn
++) {
596 struct page
*page
= pfn_to_page(pfn
);
597 struct page_ext
*page_ext
;
599 if (page_zone(page
) != zone
)
603 * To avoid having to grab zone->lock, be a little
604 * careful when reading buddy page order. The only
605 * danger is that we skip too much and potentially miss
606 * some early allocated pages, which is better than
607 * heavy lock contention.
609 if (PageBuddy(page
)) {
610 unsigned long order
= buddy_order_unsafe(page
);
612 if (order
> 0 && order
< MAX_ORDER
)
613 pfn
+= (1UL << order
) - 1;
617 if (PageReserved(page
))
620 page_ext
= lookup_page_ext(page
);
621 if (unlikely(!page_ext
))
624 /* Maybe overlapping zone */
625 if (test_bit(PAGE_EXT_OWNER
, &page_ext
->flags
))
628 /* Found early allocated page */
629 __set_page_owner_handle(page_ext
, early_handle
,
636 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
637 pgdat
->node_id
, zone
->name
, count
);
640 static void init_zones_in_node(pg_data_t
*pgdat
)
643 struct zone
*node_zones
= pgdat
->node_zones
;
645 for (zone
= node_zones
; zone
- node_zones
< MAX_NR_ZONES
; ++zone
) {
646 if (!populated_zone(zone
))
649 init_pages_in_zone(pgdat
, zone
);
653 static void init_early_allocated_pages(void)
657 for_each_online_pgdat(pgdat
)
658 init_zones_in_node(pgdat
);
661 static const struct file_operations proc_page_owner_operations
= {
662 .read
= read_page_owner
,
665 static int __init
pageowner_init(void)
667 if (!static_branch_unlikely(&page_owner_inited
)) {
668 pr_info("page_owner is disabled\n");
672 debugfs_create_file("page_owner", 0400, NULL
, NULL
,
673 &proc_page_owner_operations
);
677 late_initcall(pageowner_init
)