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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 "internal.h"
11
12static bool page_owner_disabled = true;
13DEFINE_STATIC_KEY_FALSE(page_owner_inited);
14
15static void init_early_allocated_pages(void);
16
17static int early_page_owner_param(char *buf)
18{
19 if (!buf)
20 return -EINVAL;
21
22 if (strcmp(buf, "on") == 0)
23 page_owner_disabled = false;
24
25 return 0;
26}
27early_param("page_owner", early_page_owner_param);
28
29static bool need_page_owner(void)
30{
31 if (page_owner_disabled)
32 return false;
33
34 return true;
35}
36
37static void init_page_owner(void)
38{
39 if (page_owner_disabled)
40 return;
41
42 static_branch_enable(&page_owner_inited);
43 init_early_allocated_pages();
44}
45
46struct page_ext_operations page_owner_ops = {
47 .need = need_page_owner,
48 .init = init_page_owner,
49};
50
51void __reset_page_owner(struct page *page, unsigned int order)
52{
53 int i;
54 struct page_ext *page_ext;
55
56 for (i = 0; i < (1 << order); i++) {
57 page_ext = lookup_page_ext(page + i);
58 __clear_bit(PAGE_EXT_OWNER, &page_ext->flags);
59 }
60}
61
62void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask)
63{
64 struct page_ext *page_ext = lookup_page_ext(page);
65 struct stack_trace trace = {
66 .nr_entries = 0,
67 .max_entries = ARRAY_SIZE(page_ext->trace_entries),
68 .entries = &page_ext->trace_entries[0],
69 .skip = 3,
70 };
71
72 save_stack_trace(&trace);
73
74 page_ext->order = order;
75 page_ext->gfp_mask = gfp_mask;
76 page_ext->nr_entries = trace.nr_entries;
77 page_ext->last_migrate_reason = -1;
78
79 __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
80}
81
82void __set_page_owner_migrate_reason(struct page *page, int reason)
83{
84 struct page_ext *page_ext = lookup_page_ext(page);
85
86 page_ext->last_migrate_reason = reason;
87}
88
89gfp_t __get_page_owner_gfp(struct page *page)
90{
91 struct page_ext *page_ext = lookup_page_ext(page);
92
93 return page_ext->gfp_mask;
94}
95
96void __copy_page_owner(struct page *oldpage, struct page *newpage)
97{
98 struct page_ext *old_ext = lookup_page_ext(oldpage);
99 struct page_ext *new_ext = lookup_page_ext(newpage);
100 int i;
101
102 new_ext->order = old_ext->order;
103 new_ext->gfp_mask = old_ext->gfp_mask;
104 new_ext->nr_entries = old_ext->nr_entries;
105
106 for (i = 0; i < ARRAY_SIZE(new_ext->trace_entries); i++)
107 new_ext->trace_entries[i] = old_ext->trace_entries[i];
108
109 /*
110 * We don't clear the bit on the oldpage as it's going to be freed
111 * after migration. Until then, the info can be useful in case of
112 * a bug, and the overal stats will be off a bit only temporarily.
113 * Also, migrate_misplaced_transhuge_page() can still fail the
114 * migration and then we want the oldpage to retain the info. But
115 * in that case we also don't need to explicitly clear the info from
116 * the new page, which will be freed.
117 */
118 __set_bit(PAGE_EXT_OWNER, &new_ext->flags);
119}
120
121static ssize_t
122print_page_owner(char __user *buf, size_t count, unsigned long pfn,
123 struct page *page, struct page_ext *page_ext)
124{
125 int ret;
126 int pageblock_mt, page_mt;
127 char *kbuf;
128 struct stack_trace trace = {
129 .nr_entries = page_ext->nr_entries,
130 .entries = &page_ext->trace_entries[0],
131 };
132
133 kbuf = kmalloc(count, GFP_KERNEL);
134 if (!kbuf)
135 return -ENOMEM;
136
137 ret = snprintf(kbuf, count,
138 "Page allocated via order %u, mask %#x(%pGg)\n",
139 page_ext->order, page_ext->gfp_mask,
140 &page_ext->gfp_mask);
141
142 if (ret >= count)
143 goto err;
144
145 /* Print information relevant to grouping pages by mobility */
146 pageblock_mt = get_pfnblock_migratetype(page, pfn);
147 page_mt = gfpflags_to_migratetype(page_ext->gfp_mask);
148 ret += snprintf(kbuf + ret, count - ret,
149 "PFN %lu type %s Block %lu type %s Flags %#lx(%pGp)\n",
150 pfn,
151 migratetype_names[page_mt],
152 pfn >> pageblock_order,
153 migratetype_names[pageblock_mt],
154 page->flags, &page->flags);
155
156 if (ret >= count)
157 goto err;
158
159 ret += snprint_stack_trace(kbuf + ret, count - ret, &trace, 0);
160 if (ret >= count)
161 goto err;
162
163 if (page_ext->last_migrate_reason != -1) {
164 ret += snprintf(kbuf + ret, count - ret,
165 "Page has been migrated, last migrate reason: %s\n",
166 migrate_reason_names[page_ext->last_migrate_reason]);
167 if (ret >= count)
168 goto err;
169 }
170
171 ret += snprintf(kbuf + ret, count - ret, "\n");
172 if (ret >= count)
173 goto err;
174
175 if (copy_to_user(buf, kbuf, ret))
176 ret = -EFAULT;
177
178 kfree(kbuf);
179 return ret;
180
181err:
182 kfree(kbuf);
183 return -ENOMEM;
184}
185
186void __dump_page_owner(struct page *page)
187{
188 struct page_ext *page_ext = lookup_page_ext(page);
189 struct stack_trace trace = {
190 .nr_entries = page_ext->nr_entries,
191 .entries = &page_ext->trace_entries[0],
192 };
193 gfp_t gfp_mask = page_ext->gfp_mask;
194 int mt = gfpflags_to_migratetype(gfp_mask);
195
196 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
197 pr_alert("page_owner info is not active (free page?)\n");
198 return;
199 }
200
201 pr_alert("page allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n",
202 page_ext->order, migratetype_names[mt], gfp_mask, &gfp_mask);
203 print_stack_trace(&trace, 0);
204
205 if (page_ext->last_migrate_reason != -1)
206 pr_alert("page has been migrated, last migrate reason: %s\n",
207 migrate_reason_names[page_ext->last_migrate_reason]);
208}
209
210static ssize_t
211read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
212{
213 unsigned long pfn;
214 struct page *page;
215 struct page_ext *page_ext;
216
217 if (!static_branch_unlikely(&page_owner_inited))
218 return -EINVAL;
219
220 page = NULL;
221 pfn = min_low_pfn + *ppos;
222
223 /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
224 while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
225 pfn++;
226
227 drain_all_pages(NULL);
228
229 /* Find an allocated page */
230 for (; pfn < max_pfn; pfn++) {
231 /*
232 * If the new page is in a new MAX_ORDER_NR_PAGES area,
233 * validate the area as existing, skip it if not
234 */
235 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
236 pfn += MAX_ORDER_NR_PAGES - 1;
237 continue;
238 }
239
240 /* Check for holes within a MAX_ORDER area */
241 if (!pfn_valid_within(pfn))
242 continue;
243
244 page = pfn_to_page(pfn);
245 if (PageBuddy(page)) {
246 unsigned long freepage_order = page_order_unsafe(page);
247
248 if (freepage_order < MAX_ORDER)
249 pfn += (1UL << freepage_order) - 1;
250 continue;
251 }
252
253 page_ext = lookup_page_ext(page);
254
255 /*
256 * Some pages could be missed by concurrent allocation or free,
257 * because we don't hold the zone lock.
258 */
259 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
260 continue;
261
262 /* Record the next PFN to read in the file offset */
263 *ppos = (pfn - min_low_pfn) + 1;
264
265 return print_page_owner(buf, count, pfn, page, page_ext);
266 }
267
268 return 0;
269}
270
271static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
272{
273 struct page *page;
274 struct page_ext *page_ext;
275 unsigned long pfn = zone->zone_start_pfn, block_end_pfn;
276 unsigned long end_pfn = pfn + zone->spanned_pages;
277 unsigned long count = 0;
278
279 /* Scan block by block. First and last block may be incomplete */
280 pfn = zone->zone_start_pfn;
281
282 /*
283 * Walk the zone in pageblock_nr_pages steps. If a page block spans
284 * a zone boundary, it will be double counted between zones. This does
285 * not matter as the mixed block count will still be correct
286 */
287 for (; pfn < end_pfn; ) {
288 if (!pfn_valid(pfn)) {
289 pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
290 continue;
291 }
292
293 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
294 block_end_pfn = min(block_end_pfn, end_pfn);
295
296 page = pfn_to_page(pfn);
297
298 for (; pfn < block_end_pfn; pfn++) {
299 if (!pfn_valid_within(pfn))
300 continue;
301
302 page = pfn_to_page(pfn);
303
304 /*
305 * We are safe to check buddy flag and order, because
306 * this is init stage and only single thread runs.
307 */
308 if (PageBuddy(page)) {
309 pfn += (1UL << page_order(page)) - 1;
310 continue;
311 }
312
313 if (PageReserved(page))
314 continue;
315
316 page_ext = lookup_page_ext(page);
317
318 /* Maybe overraping zone */
319 if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
320 continue;
321
322 /* Found early allocated page */
323 set_page_owner(page, 0, 0);
324 count++;
325 }
326 }
327
328 pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
329 pgdat->node_id, zone->name, count);
330}
331
332static void init_zones_in_node(pg_data_t *pgdat)
333{
334 struct zone *zone;
335 struct zone *node_zones = pgdat->node_zones;
336 unsigned long flags;
337
338 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
339 if (!populated_zone(zone))
340 continue;
341
342 spin_lock_irqsave(&zone->lock, flags);
343 init_pages_in_zone(pgdat, zone);
344 spin_unlock_irqrestore(&zone->lock, flags);
345 }
346}
347
348static void init_early_allocated_pages(void)
349{
350 pg_data_t *pgdat;
351
352 drain_all_pages(NULL);
353 for_each_online_pgdat(pgdat)
354 init_zones_in_node(pgdat);
355}
356
357static const struct file_operations proc_page_owner_operations = {
358 .read = read_page_owner,
359};
360
361static int __init pageowner_init(void)
362{
363 struct dentry *dentry;
364
365 if (!static_branch_unlikely(&page_owner_inited)) {
366 pr_info("page_owner is disabled\n");
367 return 0;
368 }
369
370 dentry = debugfs_create_file("page_owner", S_IRUSR, NULL,
371 NULL, &proc_page_owner_operations);
372 if (IS_ERR(dentry))
373 return PTR_ERR(dentry);
374
375 return 0;
376}
377late_initcall(pageowner_init)