1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * mm/debug.c
4 *
5 * mm/ specific debug routines.
6 *
7 */
8
9 #include <linux/kernel.h>
10 #include <linux/mm.h>
11 #include <linux/trace_events.h>
12 #include <linux/memcontrol.h>
13 #include <trace/events/mmflags.h>
14 #include <linux/migrate.h>
15 #include <linux/page_owner.h>
16 #include <linux/page_pinner.h>
17 #include <linux/ctype.h>
18
19 #include "internal.h"
20
21 const char *migrate_reason_names[MR_TYPES] = {
22 "compaction",
23 "memory_failure",
24 "memory_hotplug",
25 "syscall_or_cpuset",
26 "mempolicy_mbind",
27 "numa_misplaced",
28 "cma",
29 };
30
31 const struct trace_print_flags pageflag_names[] = {
32 __def_pageflag_names,
33 {0, NULL}
34 };
35
36 const struct trace_print_flags gfpflag_names[] = {
37 __def_gfpflag_names,
38 {0, NULL}
39 };
40
41 const struct trace_print_flags vmaflag_names[] = {
42 __def_vmaflag_names,
43 {0, NULL}
44 };
45
__dump_page(struct page * page,const char * reason)46 void __dump_page(struct page *page, const char *reason)
47 {
48 struct page *head = compound_head(page);
49 struct address_space *mapping;
50 bool page_poisoned = PagePoisoned(page);
51 bool compound = PageCompound(page);
52 /*
53 * Accessing the pageblock without the zone lock. It could change to
54 * "isolate" again in the meantime, but since we are just dumping the
55 * state for debugging, it should be fine to accept a bit of
56 * inaccuracy here due to racing.
57 */
58 bool page_cma = is_migrate_cma_page(page);
59 int mapcount;
60 char *type = "";
61
62 /*
63 * If struct page is poisoned don't access Page*() functions as that
64 * leads to recursive loop. Page*() check for poisoned pages, and calls
65 * dump_page() when detected.
66 */
67 if (page_poisoned) {
68 pr_warn("page:%px is uninitialized and poisoned", page);
69 goto hex_only;
70 }
71
72 if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) {
73 /*
74 * Corrupt page, so we cannot call page_mapping. Instead, do a
75 * safe subset of the steps that page_mapping() does. Caution:
76 * this will be misleading for tail pages, PageSwapCache pages,
77 * and potentially other situations. (See the page_mapping()
78 * implementation for what's missing here.)
79 */
80 unsigned long tmp = (unsigned long)page->mapping;
81
82 if (tmp & PAGE_MAPPING_ANON)
83 mapping = NULL;
84 else
85 mapping = (void *)(tmp & ~PAGE_MAPPING_FLAGS);
86 head = page;
87 compound = false;
88 } else {
89 mapping = page_mapping(page);
90 }
91
92 /*
93 * Avoid VM_BUG_ON() in page_mapcount().
94 * page->_mapcount space in struct page is used by sl[aou]b pages to
95 * encode own info.
96 */
97 mapcount = PageSlab(head) ? 0 : page_mapcount(page);
98
99 pr_warn("page:%p refcount:%d mapcount:%d mapping:%p index:%#lx pfn:%#lx\n",
100 page, page_ref_count(head), mapcount, mapping,
101 page_to_pgoff(page), page_to_pfn(page));
102 if (compound) {
103 if (hpage_pincount_available(page)) {
104 pr_warn("head:%p order:%u compound_mapcount:%d compound_pincount:%d\n",
105 head, compound_order(head),
106 head_compound_mapcount(head),
107 head_compound_pincount(head));
108 } else {
109 pr_warn("head:%p order:%u compound_mapcount:%d\n",
110 head, compound_order(head),
111 head_compound_mapcount(head));
112 }
113 }
114 if (PageKsm(page))
115 type = "ksm ";
116 else if (PageAnon(page))
117 type = "anon ";
118 else if (mapping) {
119 struct inode *host;
120 const struct address_space_operations *a_ops;
121 struct hlist_node *dentry_first;
122 struct dentry *dentry_ptr;
123 struct dentry dentry;
124 unsigned long ino;
125
126 /*
127 * mapping can be invalid pointer and we don't want to crash
128 * accessing it, so probe everything depending on it carefully
129 */
130 if (get_kernel_nofault(host, &mapping->host) ||
131 get_kernel_nofault(a_ops, &mapping->a_ops)) {
132 pr_warn("failed to read mapping contents, not a valid kernel address?\n");
133 goto out_mapping;
134 }
135
136 if (!host) {
137 pr_warn("aops:%ps\n", a_ops);
138 goto out_mapping;
139 }
140
141 if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
142 get_kernel_nofault(ino, &host->i_ino)) {
143 pr_warn("aops:%ps with invalid host inode %px\n",
144 a_ops, host);
145 goto out_mapping;
146 }
147
148 if (!dentry_first) {
149 pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
150 goto out_mapping;
151 }
152
153 dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
154 if (get_kernel_nofault(dentry, dentry_ptr)) {
155 pr_warn("aops:%ps ino:%lx with invalid dentry %px\n",
156 a_ops, ino, dentry_ptr);
157 } else {
158 /*
159 * if dentry is corrupted, the %pd handler may still
160 * crash, but it's unlikely that we reach here with a
161 * corrupted struct page
162 */
163 pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n",
164 a_ops, ino, &dentry);
165 }
166 }
167 out_mapping:
168 BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
169
170 pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags, &head->flags,
171 page_cma ? " CMA" : "");
172
173 hex_only:
174 print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
175 sizeof(unsigned long), page,
176 sizeof(struct page), false);
177 if (head != page)
178 print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
179 sizeof(unsigned long), head,
180 sizeof(struct page), false);
181
182 if (reason)
183 pr_warn("page dumped because: %s\n", reason);
184
185 #ifdef CONFIG_MEMCG
186 if (!page_poisoned && page->mem_cgroup)
187 pr_warn("page->mem_cgroup:%px\n", page->mem_cgroup);
188 #endif
189 }
190
dump_page(struct page * page,const char * reason)191 void dump_page(struct page *page, const char *reason)
192 {
193 __dump_page(page, reason);
194 dump_page_owner(page);
195 dump_page_pinner(page);
196 }
197 EXPORT_SYMBOL(dump_page);
198
199 #ifdef CONFIG_DEBUG_VM
200
dump_vma(const struct vm_area_struct * vma)201 void dump_vma(const struct vm_area_struct *vma)
202 {
203 pr_emerg("vma %px start %px end %px\n"
204 "next %px prev %px mm %px\n"
205 "prot %lx anon_vma %px vm_ops %px\n"
206 "pgoff %lx file %px private_data %px\n"
207 "flags: %#lx(%pGv)\n",
208 vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
209 vma->vm_prev, vma->vm_mm,
210 (unsigned long)pgprot_val(vma->vm_page_prot),
211 vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
212 vma->vm_file, vma->vm_private_data,
213 vma->vm_flags, &vma->vm_flags);
214 }
215 EXPORT_SYMBOL(dump_vma);
216
dump_mm(const struct mm_struct * mm)217 void dump_mm(const struct mm_struct *mm)
218 {
219 pr_emerg("mm %px mmap %px seqnum %llu task_size %lu\n"
220 #ifdef CONFIG_MMU
221 "get_unmapped_area %px\n"
222 #endif
223 "mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
224 "pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
225 "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
226 "pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
227 "start_code %lx end_code %lx start_data %lx end_data %lx\n"
228 "start_brk %lx brk %lx start_stack %lx\n"
229 "arg_start %lx arg_end %lx env_start %lx env_end %lx\n"
230 "binfmt %px flags %lx core_state %px\n"
231 #ifdef CONFIG_AIO
232 "ioctx_table %px\n"
233 #endif
234 #ifdef CONFIG_MEMCG
235 "owner %px "
236 #endif
237 "exe_file %px\n"
238 #ifdef CONFIG_MMU_NOTIFIER
239 "notifier_subscriptions %px\n"
240 #endif
241 #ifdef CONFIG_NUMA_BALANCING
242 "numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n"
243 #endif
244 "tlb_flush_pending %d\n"
245 "def_flags: %#lx(%pGv)\n",
246
247 mm, mm->mmap, (long long) mm->vmacache_seqnum, mm->task_size,
248 #ifdef CONFIG_MMU
249 mm->get_unmapped_area,
250 #endif
251 mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
252 mm->pgd, atomic_read(&mm->mm_users),
253 atomic_read(&mm->mm_count),
254 mm_pgtables_bytes(mm),
255 mm->map_count,
256 mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm,
257 (u64)atomic64_read(&mm->pinned_vm),
258 mm->data_vm, mm->exec_vm, mm->stack_vm,
259 mm->start_code, mm->end_code, mm->start_data, mm->end_data,
260 mm->start_brk, mm->brk, mm->start_stack,
261 mm->arg_start, mm->arg_end, mm->env_start, mm->env_end,
262 mm->binfmt, mm->flags, mm->core_state,
263 #ifdef CONFIG_AIO
264 mm->ioctx_table,
265 #endif
266 #ifdef CONFIG_MEMCG
267 mm->owner,
268 #endif
269 mm->exe_file,
270 #ifdef CONFIG_MMU_NOTIFIER
271 mm->notifier_subscriptions,
272 #endif
273 #ifdef CONFIG_NUMA_BALANCING
274 mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq,
275 #endif
276 atomic_read(&mm->tlb_flush_pending),
277 mm->def_flags, &mm->def_flags
278 );
279 }
280
281 static bool page_init_poisoning __read_mostly = true;
282
setup_vm_debug(char * str)283 static int __init setup_vm_debug(char *str)
284 {
285 bool __page_init_poisoning = true;
286
287 /*
288 * Calling vm_debug with no arguments is equivalent to requesting
289 * to enable all debugging options we can control.
290 */
291 if (*str++ != '=' || !*str)
292 goto out;
293
294 __page_init_poisoning = false;
295 if (*str == '-')
296 goto out;
297
298 while (*str) {
299 switch (tolower(*str)) {
300 case'p':
301 __page_init_poisoning = true;
302 break;
303 default:
304 pr_err("vm_debug option '%c' unknown. skipped\n",
305 *str);
306 }
307
308 str++;
309 }
310 out:
311 if (page_init_poisoning && !__page_init_poisoning)
312 pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n");
313
314 page_init_poisoning = __page_init_poisoning;
315
316 return 1;
317 }
318 __setup("vm_debug", setup_vm_debug);
319
page_init_poison(struct page * page,size_t size)320 void page_init_poison(struct page *page, size_t size)
321 {
322 if (page_init_poisoning)
323 memset(page, PAGE_POISON_PATTERN, size);
324 }
325 EXPORT_SYMBOL_GPL(page_init_poison);
326 #endif /* CONFIG_DEBUG_VM */
327