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 "internal.h"
9
10static bool page_owner_disabled = true;
11bool page_owner_inited __read_mostly;
12
13static void init_early_allocated_pages(void);
14
15static int early_page_owner_param(char *buf)
16{
17	if (!buf)
18		return -EINVAL;
19
20	if (strcmp(buf, "on") == 0)
21		page_owner_disabled = false;
22
23	return 0;
24}
25early_param("page_owner", early_page_owner_param);
26
27static bool need_page_owner(void)
28{
29	if (page_owner_disabled)
30		return false;
31
32	return true;
33}
34
35static void init_page_owner(void)
36{
37	if (page_owner_disabled)
38		return;
39
40	page_owner_inited = true;
41	init_early_allocated_pages();
42}
43
44struct page_ext_operations page_owner_ops = {
45	.need = need_page_owner,
46	.init = init_page_owner,
47};
48
49void __reset_page_owner(struct page *page, unsigned int order)
50{
51	int i;
52	struct page_ext *page_ext;
53
54	for (i = 0; i < (1 << order); i++) {
55		page_ext = lookup_page_ext(page + i);
56		__clear_bit(PAGE_EXT_OWNER, &page_ext->flags);
57	}
58}
59
60void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask)
61{
62	struct page_ext *page_ext = lookup_page_ext(page);
63	struct stack_trace trace = {
64		.nr_entries = 0,
65		.max_entries = ARRAY_SIZE(page_ext->trace_entries),
66		.entries = &page_ext->trace_entries[0],
67		.skip = 3,
68	};
69
70	save_stack_trace(&trace);
71
72	page_ext->order = order;
73	page_ext->gfp_mask = gfp_mask;
74	page_ext->nr_entries = trace.nr_entries;
75
76	__set_bit(PAGE_EXT_OWNER, &page_ext->flags);
77}
78
79gfp_t __get_page_owner_gfp(struct page *page)
80{
81	struct page_ext *page_ext = lookup_page_ext(page);
82
83	return page_ext->gfp_mask;
84}
85
86static ssize_t
87print_page_owner(char __user *buf, size_t count, unsigned long pfn,
88		struct page *page, struct page_ext *page_ext)
89{
90	int ret;
91	int pageblock_mt, page_mt;
92	char *kbuf;
93	struct stack_trace trace = {
94		.nr_entries = page_ext->nr_entries,
95		.entries = &page_ext->trace_entries[0],
96	};
97
98	kbuf = kmalloc(count, GFP_KERNEL);
99	if (!kbuf)
100		return -ENOMEM;
101
102	ret = snprintf(kbuf, count,
103			"Page allocated via order %u, mask 0x%x\n",
104			page_ext->order, page_ext->gfp_mask);
105
106	if (ret >= count)
107		goto err;
108
109	/* Print information relevant to grouping pages by mobility */
110	pageblock_mt = get_pfnblock_migratetype(page, pfn);
111	page_mt  = gfpflags_to_migratetype(page_ext->gfp_mask);
112	ret += snprintf(kbuf + ret, count - ret,
113			"PFN %lu Block %lu type %d %s Flags %s%s%s%s%s%s%s%s%s%s%s%s\n",
114			pfn,
115			pfn >> pageblock_order,
116			pageblock_mt,
117			pageblock_mt != page_mt ? "Fallback" : "        ",
118			PageLocked(page)	? "K" : " ",
119			PageError(page)		? "E" : " ",
120			PageReferenced(page)	? "R" : " ",
121			PageUptodate(page)	? "U" : " ",
122			PageDirty(page)		? "D" : " ",
123			PageLRU(page)		? "L" : " ",
124			PageActive(page)	? "A" : " ",
125			PageSlab(page)		? "S" : " ",
126			PageWriteback(page)	? "W" : " ",
127			PageCompound(page)	? "C" : " ",
128			PageSwapCache(page)	? "B" : " ",
129			PageMappedToDisk(page)	? "M" : " ");
130
131	if (ret >= count)
132		goto err;
133
134	ret += snprint_stack_trace(kbuf + ret, count - ret, &trace, 0);
135	if (ret >= count)
136		goto err;
137
138	ret += snprintf(kbuf + ret, count - ret, "\n");
139	if (ret >= count)
140		goto err;
141
142	if (copy_to_user(buf, kbuf, ret))
143		ret = -EFAULT;
144
145	kfree(kbuf);
146	return ret;
147
148err:
149	kfree(kbuf);
150	return -ENOMEM;
151}
152
153static ssize_t
154read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
155{
156	unsigned long pfn;
157	struct page *page;
158	struct page_ext *page_ext;
159
160	if (!page_owner_inited)
161		return -EINVAL;
162
163	page = NULL;
164	pfn = min_low_pfn + *ppos;
165
166	/* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
167	while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
168		pfn++;
169
170	drain_all_pages(NULL);
171
172	/* Find an allocated page */
173	for (; pfn < max_pfn; pfn++) {
174		/*
175		 * If the new page is in a new MAX_ORDER_NR_PAGES area,
176		 * validate the area as existing, skip it if not
177		 */
178		if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
179			pfn += MAX_ORDER_NR_PAGES - 1;
180			continue;
181		}
182
183		/* Check for holes within a MAX_ORDER area */
184		if (!pfn_valid_within(pfn))
185			continue;
186
187		page = pfn_to_page(pfn);
188		if (PageBuddy(page)) {
189			unsigned long freepage_order = page_order_unsafe(page);
190
191			if (freepage_order < MAX_ORDER)
192				pfn += (1UL << freepage_order) - 1;
193			continue;
194		}
195
196		page_ext = lookup_page_ext(page);
197
198		/*
199		 * Some pages could be missed by concurrent allocation or free,
200		 * because we don't hold the zone lock.
201		 */
202		if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
203			continue;
204
205		/* Record the next PFN to read in the file offset */
206		*ppos = (pfn - min_low_pfn) + 1;
207
208		return print_page_owner(buf, count, pfn, page, page_ext);
209	}
210
211	return 0;
212}
213
214static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
215{
216	struct page *page;
217	struct page_ext *page_ext;
218	unsigned long pfn = zone->zone_start_pfn, block_end_pfn;
219	unsigned long end_pfn = pfn + zone->spanned_pages;
220	unsigned long count = 0;
221
222	/* Scan block by block. First and last block may be incomplete */
223	pfn = zone->zone_start_pfn;
224
225	/*
226	 * Walk the zone in pageblock_nr_pages steps. If a page block spans
227	 * a zone boundary, it will be double counted between zones. This does
228	 * not matter as the mixed block count will still be correct
229	 */
230	for (; pfn < end_pfn; ) {
231		if (!pfn_valid(pfn)) {
232			pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
233			continue;
234		}
235
236		block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
237		block_end_pfn = min(block_end_pfn, end_pfn);
238
239		page = pfn_to_page(pfn);
240
241		for (; pfn < block_end_pfn; pfn++) {
242			if (!pfn_valid_within(pfn))
243				continue;
244
245			page = pfn_to_page(pfn);
246
247			/*
248			 * We are safe to check buddy flag and order, because
249			 * this is init stage and only single thread runs.
250			 */
251			if (PageBuddy(page)) {
252				pfn += (1UL << page_order(page)) - 1;
253				continue;
254			}
255
256			if (PageReserved(page))
257				continue;
258
259			page_ext = lookup_page_ext(page);
260
261			/* Maybe overraping zone */
262			if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
263				continue;
264
265			/* Found early allocated page */
266			set_page_owner(page, 0, 0);
267			count++;
268		}
269	}
270
271	pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
272		pgdat->node_id, zone->name, count);
273}
274
275static void init_zones_in_node(pg_data_t *pgdat)
276{
277	struct zone *zone;
278	struct zone *node_zones = pgdat->node_zones;
279	unsigned long flags;
280
281	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
282		if (!populated_zone(zone))
283			continue;
284
285		spin_lock_irqsave(&zone->lock, flags);
286		init_pages_in_zone(pgdat, zone);
287		spin_unlock_irqrestore(&zone->lock, flags);
288	}
289}
290
291static void init_early_allocated_pages(void)
292{
293	pg_data_t *pgdat;
294
295	drain_all_pages(NULL);
296	for_each_online_pgdat(pgdat)
297		init_zones_in_node(pgdat);
298}
299
300static const struct file_operations proc_page_owner_operations = {
301	.read		= read_page_owner,
302};
303
304static int __init pageowner_init(void)
305{
306	struct dentry *dentry;
307
308	if (!page_owner_inited) {
309		pr_info("page_owner is disabled\n");
310		return 0;
311	}
312
313	dentry = debugfs_create_file("page_owner", S_IRUSR, NULL,
314			NULL, &proc_page_owner_operations);
315	if (IS_ERR(dentry))
316		return PTR_ERR(dentry);
317
318	return 0;
319}
320late_initcall(pageowner_init)
321