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/ctype.h>
17
18 #include "internal.h"
19
20 const char *migrate_reason_names[MR_TYPES] = {
21 "compaction",
22 "memory_failure",
23 "memory_hotplug",
24 "syscall_or_cpuset",
25 "mempolicy_mbind",
26 "numa_misplaced",
27 "contig_range",
28 "longterm_pin",
29 "demotion",
30 };
31
32 const struct trace_print_flags pageflag_names[] = {
33 __def_pageflag_names,
34 {0, NULL}
35 };
36
37 const struct trace_print_flags gfpflag_names[] = {
38 __def_gfpflag_names,
39 {0, NULL}
40 };
41
42 const struct trace_print_flags vmaflag_names[] = {
43 __def_vmaflag_names,
44 {0, NULL}
45 };
46
__dump_page(struct page * page)47 static void __dump_page(struct page *page)
48 {
49 struct page *head = compound_head(page);
50 struct address_space *mapping;
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 if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) {
63 /*
64 * Corrupt page, so we cannot call page_mapping. Instead, do a
65 * safe subset of the steps that page_mapping() does. Caution:
66 * this will be misleading for tail pages, PageSwapCache pages,
67 * and potentially other situations. (See the page_mapping()
68 * implementation for what's missing here.)
69 */
70 unsigned long tmp = (unsigned long)page->mapping;
71
72 if (tmp & PAGE_MAPPING_ANON)
73 mapping = NULL;
74 else
75 mapping = (void *)(tmp & ~PAGE_MAPPING_FLAGS);
76 head = page;
77 compound = false;
78 } else {
79 mapping = page_mapping(page);
80 }
81
82 /*
83 * Avoid VM_BUG_ON() in page_mapcount().
84 * page->_mapcount space in struct page is used by sl[aou]b pages to
85 * encode own info.
86 */
87 mapcount = PageSlab(head) ? 0 : page_mapcount(page);
88
89 pr_warn("page:%p refcount:%d mapcount:%d mapping:%p index:%#lx pfn:%#lx\n",
90 page, page_ref_count(head), mapcount, mapping,
91 page_to_pgoff(page), page_to_pfn(page));
92 if (compound) {
93 if (hpage_pincount_available(page)) {
94 pr_warn("head:%p order:%u compound_mapcount:%d compound_pincount:%d\n",
95 head, compound_order(head),
96 head_compound_mapcount(head),
97 head_compound_pincount(head));
98 } else {
99 pr_warn("head:%p order:%u compound_mapcount:%d\n",
100 head, compound_order(head),
101 head_compound_mapcount(head));
102 }
103 }
104
105 #ifdef CONFIG_MEMCG
106 if (head->memcg_data)
107 pr_warn("memcg:%lx\n", head->memcg_data);
108 #endif
109 if (PageKsm(page))
110 type = "ksm ";
111 else if (PageAnon(page))
112 type = "anon ";
113 else if (mapping) {
114 struct inode *host;
115 const struct address_space_operations *a_ops;
116 struct hlist_node *dentry_first;
117 struct dentry *dentry_ptr;
118 struct dentry dentry;
119 unsigned long ino;
120
121 /*
122 * mapping can be invalid pointer and we don't want to crash
123 * accessing it, so probe everything depending on it carefully
124 */
125 if (get_kernel_nofault(host, &mapping->host) ||
126 get_kernel_nofault(a_ops, &mapping->a_ops)) {
127 pr_warn("failed to read mapping contents, not a valid kernel address?\n");
128 goto out_mapping;
129 }
130
131 if (!host) {
132 pr_warn("aops:%ps\n", a_ops);
133 goto out_mapping;
134 }
135
136 if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
137 get_kernel_nofault(ino, &host->i_ino)) {
138 pr_warn("aops:%ps with invalid host inode %px\n",
139 a_ops, host);
140 goto out_mapping;
141 }
142
143 if (!dentry_first) {
144 pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
145 goto out_mapping;
146 }
147
148 dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
149 if (get_kernel_nofault(dentry, dentry_ptr)) {
150 pr_warn("aops:%ps ino:%lx with invalid dentry %px\n",
151 a_ops, ino, dentry_ptr);
152 } else {
153 /*
154 * if dentry is corrupted, the %pd handler may still
155 * crash, but it's unlikely that we reach here with a
156 * corrupted struct page
157 */
158 pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n",
159 a_ops, ino, &dentry);
160 }
161 }
162 out_mapping:
163 BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
164
165 pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags, &head->flags,
166 page_cma ? " CMA" : "");
167 print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
168 sizeof(unsigned long), page,
169 sizeof(struct page), false);
170 if (head != page)
171 print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
172 sizeof(unsigned long), head,
173 sizeof(struct page), false);
174 }
175
dump_page(struct page * page,const char * reason)176 void dump_page(struct page *page, const char *reason)
177 {
178 if (PagePoisoned(page))
179 pr_warn("page:%p is uninitialized and poisoned", page);
180 else
181 __dump_page(page);
182 if (reason)
183 pr_warn("page dumped because: %s\n", reason);
184 dump_page_owner(page);
185 }
186 EXPORT_SYMBOL(dump_page);
187
188 #ifdef CONFIG_DEBUG_VM
189
dump_vma(const struct vm_area_struct * vma)190 void dump_vma(const struct vm_area_struct *vma)
191 {
192 pr_emerg("vma %px start %px end %px\n"
193 "next %px prev %px mm %px\n"
194 "prot %lx anon_vma %px vm_ops %px\n"
195 "pgoff %lx file %px private_data %px\n"
196 "flags: %#lx(%pGv)\n",
197 vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
198 vma->vm_prev, vma->vm_mm,
199 (unsigned long)pgprot_val(vma->vm_page_prot),
200 vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
201 vma->vm_file, vma->vm_private_data,
202 vma->vm_flags, &vma->vm_flags);
203 }
204 EXPORT_SYMBOL(dump_vma);
205
dump_mm(const struct mm_struct * mm)206 void dump_mm(const struct mm_struct *mm)
207 {
208 pr_emerg("mm %px mmap %px seqnum %llu task_size %lu\n"
209 #ifdef CONFIG_MMU
210 "get_unmapped_area %px\n"
211 #endif
212 "mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
213 "pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
214 "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
215 "pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
216 "start_code %lx end_code %lx start_data %lx end_data %lx\n"
217 "start_brk %lx brk %lx start_stack %lx\n"
218 "arg_start %lx arg_end %lx env_start %lx env_end %lx\n"
219 "binfmt %px flags %lx core_state %px\n"
220 #ifdef CONFIG_AIO
221 "ioctx_table %px\n"
222 #endif
223 #ifdef CONFIG_MEMCG
224 "owner %px "
225 #endif
226 "exe_file %px\n"
227 #ifdef CONFIG_MMU_NOTIFIER
228 "notifier_subscriptions %px\n"
229 #endif
230 #ifdef CONFIG_NUMA_BALANCING
231 "numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n"
232 #endif
233 "tlb_flush_pending %d\n"
234 "def_flags: %#lx(%pGv)\n",
235
236 mm, mm->mmap, (long long) mm->vmacache_seqnum, mm->task_size,
237 #ifdef CONFIG_MMU
238 mm->get_unmapped_area,
239 #endif
240 mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
241 mm->pgd, atomic_read(&mm->mm_users),
242 atomic_read(&mm->mm_count),
243 mm_pgtables_bytes(mm),
244 mm->map_count,
245 mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm,
246 (u64)atomic64_read(&mm->pinned_vm),
247 mm->data_vm, mm->exec_vm, mm->stack_vm,
248 mm->start_code, mm->end_code, mm->start_data, mm->end_data,
249 mm->start_brk, mm->brk, mm->start_stack,
250 mm->arg_start, mm->arg_end, mm->env_start, mm->env_end,
251 mm->binfmt, mm->flags, mm->core_state,
252 #ifdef CONFIG_AIO
253 mm->ioctx_table,
254 #endif
255 #ifdef CONFIG_MEMCG
256 mm->owner,
257 #endif
258 mm->exe_file,
259 #ifdef CONFIG_MMU_NOTIFIER
260 mm->notifier_subscriptions,
261 #endif
262 #ifdef CONFIG_NUMA_BALANCING
263 mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq,
264 #endif
265 atomic_read(&mm->tlb_flush_pending),
266 mm->def_flags, &mm->def_flags
267 );
268 }
269
270 static bool page_init_poisoning __read_mostly = true;
271
setup_vm_debug(char * str)272 static int __init setup_vm_debug(char *str)
273 {
274 bool __page_init_poisoning = true;
275
276 /*
277 * Calling vm_debug with no arguments is equivalent to requesting
278 * to enable all debugging options we can control.
279 */
280 if (*str++ != '=' || !*str)
281 goto out;
282
283 __page_init_poisoning = false;
284 if (*str == '-')
285 goto out;
286
287 while (*str) {
288 switch (tolower(*str)) {
289 case'p':
290 __page_init_poisoning = true;
291 break;
292 default:
293 pr_err("vm_debug option '%c' unknown. skipped\n",
294 *str);
295 }
296
297 str++;
298 }
299 out:
300 if (page_init_poisoning && !__page_init_poisoning)
301 pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n");
302
303 page_init_poisoning = __page_init_poisoning;
304
305 return 1;
306 }
307 __setup("vm_debug", setup_vm_debug);
308
page_init_poison(struct page * page,size_t size)309 void page_init_poison(struct page *page, size_t size)
310 {
311 if (page_init_poisoning)
312 memset(page, PAGE_POISON_PATTERN, size);
313 }
314 EXPORT_SYMBOL_GPL(page_init_poison);
315 #endif /* CONFIG_DEBUG_VM */
316
