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