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 "cma",
28 };
29
30 const struct trace_print_flags pageflag_names[] = {
31 __def_pageflag_names,
32 #ifdef CONFIG_PAGE_TRACING
33 {1UL << PG_skb, "skb"},
34 {1UL << PG_zspage, "zspage"},
35 #endif
36 {0, NULL}
37 };
38
39 const struct trace_print_flags gfpflag_names[] = {
40 __def_gfpflag_names,
41 {0, NULL}
42 };
43
44 const struct trace_print_flags vmaflag_names[] = {
45 __def_vmaflag_names,
46 {0, NULL}
47 };
48
__dump_page(struct page * page,const char * reason)49 void __dump_page(struct page *page, const char *reason)
50 {
51 struct page *head = compound_head(page);
52 struct address_space *mapping;
53 bool page_poisoned = PagePoisoned(page);
54 bool compound = PageCompound(page);
55 /*
56 * Accessing the pageblock without the zone lock. It could change to
57 * "isolate" again in the meantime, but since we are just dumping the
58 * state for debugging, it should be fine to accept a bit of
59 * inaccuracy here due to racing.
60 */
61 bool page_cma = is_migrate_cma_page(page);
62 int mapcount;
63 char *type = "";
64
65 /*
66 * If struct page is poisoned don't access Page*() functions as that
67 * leads to recursive loop. Page*() check for poisoned pages, and calls
68 * dump_page() when detected.
69 */
70 if (page_poisoned) {
71 pr_warn("page:%px is uninitialized and poisoned", page);
72 goto hex_only;
73 }
74
75 if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) {
76 /*
77 * Corrupt page, so we cannot call page_mapping. Instead, do a
78 * safe subset of the steps that page_mapping() does. Caution:
79 * this will be misleading for tail pages, PageSwapCache pages,
80 * and potentially other situations. (See the page_mapping()
81 * implementation for what's missing here.)
82 */
83 unsigned long tmp = (unsigned long)page->mapping;
84
85 if (tmp & PAGE_MAPPING_ANON)
86 mapping = NULL;
87 else
88 mapping = (void *)(tmp & ~PAGE_MAPPING_FLAGS);
89 head = page;
90 compound = false;
91 } else {
92 mapping = page_mapping(page);
93 }
94
95 /*
96 * Avoid VM_BUG_ON() in page_mapcount().
97 * page->_mapcount space in struct page is used by sl[aou]b pages to
98 * encode own info.
99 */
100 mapcount = PageSlab(head) ? 0 : page_mapcount(page);
101
102 pr_warn("page:%p refcount:%d mapcount:%d mapping:%p index:%#lx pfn:%#lx\n",
103 page, page_ref_count(head), mapcount, mapping,
104 page_to_pgoff(page), page_to_pfn(page));
105 if (compound) {
106 if (hpage_pincount_available(page)) {
107 pr_warn("head:%p order:%u compound_mapcount:%d compound_pincount:%d\n",
108 head, compound_order(head),
109 head_compound_mapcount(head),
110 head_compound_pincount(head));
111 } else {
112 pr_warn("head:%p order:%u compound_mapcount:%d\n",
113 head, compound_order(head),
114 head_compound_mapcount(head));
115 }
116 }
117 if (PageKsm(page))
118 type = "ksm ";
119 else if (PageAnon(page))
120 type = "anon ";
121 else if (mapping) {
122 struct inode *host;
123 const struct address_space_operations *a_ops;
124 struct hlist_node *dentry_first;
125 struct dentry *dentry_ptr;
126 struct dentry dentry;
127 unsigned long ino;
128
129 /*
130 * mapping can be invalid pointer and we don't want to crash
131 * accessing it, so probe everything depending on it carefully
132 */
133 if (get_kernel_nofault(host, &mapping->host) ||
134 get_kernel_nofault(a_ops, &mapping->a_ops)) {
135 pr_warn("failed to read mapping contents, not a valid kernel address?\n");
136 goto out_mapping;
137 }
138
139 if (!host) {
140 pr_warn("aops:%ps\n", a_ops);
141 goto out_mapping;
142 }
143
144 if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
145 get_kernel_nofault(ino, &host->i_ino)) {
146 pr_warn("aops:%ps with invalid host inode %px\n",
147 a_ops, host);
148 goto out_mapping;
149 }
150
151 if (!dentry_first) {
152 pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
153 goto out_mapping;
154 }
155
156 dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
157 if (get_kernel_nofault(dentry, dentry_ptr)) {
158 pr_warn("aops:%ps ino:%lx with invalid dentry %px\n",
159 a_ops, ino, dentry_ptr);
160 } else {
161 /*
162 * if dentry is corrupted, the %pd handler may still
163 * crash, but it's unlikely that we reach here with a
164 * corrupted struct page
165 */
166 pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n",
167 a_ops, ino, &dentry);
168 }
169 }
170 out_mapping:
171 BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
172
173 pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags, &head->flags,
174 page_cma ? " CMA" : "");
175
176 hex_only:
177 print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
178 sizeof(unsigned long), page,
179 sizeof(struct page), false);
180 if (head != page)
181 print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
182 sizeof(unsigned long), head,
183 sizeof(struct page), false);
184
185 if (reason)
186 pr_warn("page dumped because: %s\n", reason);
187
188 #ifdef CONFIG_MEMCG
189 if (!page_poisoned && page->mem_cgroup)
190 pr_warn("page->mem_cgroup:%px\n", page->mem_cgroup);
191 #endif
192 }
193
dump_page(struct page * page,const char * reason)194 void dump_page(struct page *page, const char *reason)
195 {
196 __dump_page(page, reason);
197 dump_page_owner(page);
198 }
199 EXPORT_SYMBOL(dump_page);
200
201 #ifdef CONFIG_DEBUG_VM
202
dump_vma(const struct vm_area_struct * vma)203 void dump_vma(const struct vm_area_struct *vma)
204 {
205 pr_emerg("vma %px start %px end %px\n"
206 "next %px prev %px mm %px\n"
207 "prot %lx anon_vma %px vm_ops %px\n"
208 "pgoff %lx file %px private_data %px\n"
209 "flags: %#lx(%pGv)\n",
210 vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
211 vma->vm_prev, vma->vm_mm,
212 (unsigned long)pgprot_val(vma->vm_page_prot),
213 vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
214 vma->vm_file, vma->vm_private_data,
215 vma->vm_flags, &vma->vm_flags);
216 }
217 EXPORT_SYMBOL(dump_vma);
218
dump_mm(const struct mm_struct * mm)219 void dump_mm(const struct mm_struct *mm)
220 {
221 pr_emerg("mm %px mmap %px seqnum %llu task_size %lu\n"
222 #ifdef CONFIG_MMU
223 "get_unmapped_area %px\n"
224 #endif
225 "mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
226 "pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
227 "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
228 "pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
229 "start_code %lx end_code %lx start_data %lx end_data %lx\n"
230 "start_brk %lx brk %lx start_stack %lx\n"
231 "arg_start %lx arg_end %lx env_start %lx env_end %lx\n"
232 "binfmt %px flags %lx core_state %px\n"
233 #ifdef CONFIG_AIO
234 "ioctx_table %px\n"
235 #endif
236 #ifdef CONFIG_MEMCG
237 "owner %px "
238 #endif
239 "exe_file %px\n"
240 #ifdef CONFIG_MMU_NOTIFIER
241 "notifier_subscriptions %px\n"
242 #endif
243 #ifdef CONFIG_NUMA_BALANCING
244 "numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n"
245 #endif
246 "tlb_flush_pending %d\n"
247 "def_flags: %#lx(%pGv)\n",
248
249 mm, mm->mmap, (long long) mm->vmacache_seqnum, mm->task_size,
250 #ifdef CONFIG_MMU
251 mm->get_unmapped_area,
252 #endif
253 mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
254 mm->pgd, atomic_read(&mm->mm_users),
255 atomic_read(&mm->mm_count),
256 mm_pgtables_bytes(mm),
257 mm->map_count,
258 mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm,
259 (u64)atomic64_read(&mm->pinned_vm),
260 mm->data_vm, mm->exec_vm, mm->stack_vm,
261 mm->start_code, mm->end_code, mm->start_data, mm->end_data,
262 mm->start_brk, mm->brk, mm->start_stack,
263 mm->arg_start, mm->arg_end, mm->env_start, mm->env_end,
264 mm->binfmt, mm->flags, mm->core_state,
265 #ifdef CONFIG_AIO
266 mm->ioctx_table,
267 #endif
268 #ifdef CONFIG_MEMCG
269 mm->owner,
270 #endif
271 mm->exe_file,
272 #ifdef CONFIG_MMU_NOTIFIER
273 mm->notifier_subscriptions,
274 #endif
275 #ifdef CONFIG_NUMA_BALANCING
276 mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq,
277 #endif
278 atomic_read(&mm->tlb_flush_pending),
279 mm->def_flags, &mm->def_flags
280 );
281 }
282
283 static bool page_init_poisoning __read_mostly = true;
284
setup_vm_debug(char * str)285 static int __init setup_vm_debug(char *str)
286 {
287 bool __page_init_poisoning = true;
288
289 /*
290 * Calling vm_debug with no arguments is equivalent to requesting
291 * to enable all debugging options we can control.
292 */
293 if (*str++ != '=' || !*str)
294 goto out;
295
296 __page_init_poisoning = false;
297 if (*str == '-')
298 goto out;
299
300 while (*str) {
301 switch (tolower(*str)) {
302 case'p':
303 __page_init_poisoning = true;
304 break;
305 default:
306 pr_err("vm_debug option '%c' unknown. skipped\n",
307 *str);
308 }
309
310 str++;
311 }
312 out:
313 if (page_init_poisoning && !__page_init_poisoning)
314 pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n");
315
316 page_init_poisoning = __page_init_poisoning;
317
318 return 1;
319 }
320 __setup("vm_debug", setup_vm_debug);
321
page_init_poison(struct page * page,size_t size)322 void page_init_poison(struct page *page, size_t size)
323 {
324 if (page_init_poisoning)
325 memset(page, PAGE_POISON_PATTERN, size);
326 }
327 EXPORT_SYMBOL_GPL(page_init_poison);
328 #endif /* CONFIG_DEBUG_VM */
329