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mm: memcontrol: fix possible memcg leak due to interrupted reclaim
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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 "internal.h"
9
10 static bool page_owner_disabled = true;
11 bool page_owner_inited __read_mostly;
12
13 static void init_early_allocated_pages(void);
14
15 static 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 }
25 early_param("page_owner", early_page_owner_param);
26
27 static bool need_page_owner(void)
28 {
29         if (page_owner_disabled)
30                 return false;
31
32         return true;
33 }
34
35 static 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
44 struct page_ext_operations page_owner_ops = {
45         .need = need_page_owner,
46         .init = init_page_owner,
47 };
48
49 void __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
60 void __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
79 gfp_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
86 static ssize_t
87 print_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
148 err:
149         kfree(kbuf);
150         return -ENOMEM;
151 }
152
153 static ssize_t
154 read_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
214 static 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
275 static 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
291 static 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
300 static const struct file_operations proc_page_owner_operations = {
301         .read           = read_page_owner,
302 };
303
304 static 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 }
320 late_initcall(pageowner_init)