xref: /openbmc/linux/mm/debug.c (revision a89a501c) 
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 void __dump_page(struct page *page, const char *reason)
46 {
47 	struct page *head = compound_head(page);
48 	struct address_space *mapping;
49 	bool page_poisoned = PagePoisoned(page);
50 	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 	bool page_cma = is_migrate_cma_page(page);
58 	int mapcount;
59 	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 	if (page_poisoned) {
67 		pr_warn("page:%px is uninitialized and poisoned", page);
68 		goto hex_only;
69 	}
70 
71 	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 		unsigned long tmp = (unsigned long)page->mapping;
80 
81 		if (tmp & PAGE_MAPPING_ANON)
82 			mapping = NULL;
83 		else
84 			mapping = (void *)(tmp & ~PAGE_MAPPING_FLAGS);
85 		head = page;
86 		compound = false;
87 	} else {
88 		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 	mapcount = PageSlab(head) ? 0 : page_mapcount(page);
97 
98 	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 	if (compound) {
102 		if (hpage_pincount_available(page)) {
103 			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 			pr_warn("head:%p order:%u compound_mapcount:%d\n",
109 					head, compound_order(head),
110 					head_compound_mapcount(head));
111 		}
112 	}
113 	if (PageKsm(page))
114 		type = "ksm ";
115 	else if (PageAnon(page))
116 		type = "anon ";
117 	else if (mapping) {
118 		struct inode *host;
119 		const struct address_space_operations *a_ops;
120 		struct hlist_node *dentry_first;
121 		struct dentry *dentry_ptr;
122 		struct dentry dentry;
123 		unsigned long ino;
124 
125 		/*
126 		 * mapping can be invalid pointer and we don't want to crash
127 		 * accessing it, so probe everything depending on it carefully
128 		 */
129 		if (get_kernel_nofault(host, &mapping->host) ||
130 		    get_kernel_nofault(a_ops, &mapping->a_ops)) {
131 			pr_warn("failed to read mapping contents, not a valid kernel address?\n");
132 			goto out_mapping;
133 		}
134 
135 		if (!host) {
136 			pr_warn("aops:%ps\n", a_ops);
137 			goto out_mapping;
138 		}
139 
140 		if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
141 		    get_kernel_nofault(ino, &host->i_ino)) {
142 			pr_warn("aops:%ps with invalid host inode %px\n",
143 					a_ops, host);
144 			goto out_mapping;
145 		}
146 
147 		if (!dentry_first) {
148 			pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
149 			goto out_mapping;
150 		}
151 
152 		dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
153 		if (get_kernel_nofault(dentry, dentry_ptr)) {
154 			pr_warn("aops:%ps ino:%lx with invalid dentry %px\n",
155 					a_ops, ino, dentry_ptr);
156 		} else {
157 			/*
158 			 * if dentry is corrupted, the %pd handler may still
159 			 * crash, but it's unlikely that we reach here with a
160 			 * corrupted struct page
161 			 */
162 			pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n",
163 					a_ops, ino, &dentry);
164 		}
165 	}
166 out_mapping:
167 	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
168 
169 	pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags, &head->flags,
170 		page_cma ? " CMA" : "");
171 
172 hex_only:
173 	print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
174 			sizeof(unsigned long), page,
175 			sizeof(struct page), false);
176 	if (head != page)
177 		print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
178 			sizeof(unsigned long), head,
179 			sizeof(struct page), false);
180 
181 	if (reason)
182 		pr_warn("page dumped because: %s\n", reason);
183 
184 #ifdef CONFIG_MEMCG
185 	if (!page_poisoned && page->mem_cgroup)
186 		pr_warn("page->mem_cgroup:%px\n", page->mem_cgroup);
187 #endif
188 }
189 
190 void dump_page(struct page *page, const char *reason)
191 {
192 	__dump_page(page, reason);
193 	dump_page_owner(page);
194 }
195 EXPORT_SYMBOL(dump_page);
196 
197 #ifdef CONFIG_DEBUG_VM
198 
199 void dump_vma(const struct vm_area_struct *vma)
200 {
201 	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 }
213 EXPORT_SYMBOL(dump_vma);
214 
215 void dump_mm(const struct mm_struct *mm)
216 {
217 	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 }
278 
279 static bool page_init_poisoning __read_mostly = true;
280 
281 static int __init setup_vm_debug(char *str)
282 {
283 	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 	if (*str++ != '=' || !*str)
290 		goto out;
291 
292 	__page_init_poisoning = false;
293 	if (*str == '-')
294 		goto out;
295 
296 	while (*str) {
297 		switch (tolower(*str)) {
298 		case'p':
299 			__page_init_poisoning = true;
300 			break;
301 		default:
302 			pr_err("vm_debug option '%c' unknown. skipped\n",
303 			       *str);
304 		}
305 
306 		str++;
307 	}
308 out:
309 	if (page_init_poisoning && !__page_init_poisoning)
310 		pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n");
311 
312 	page_init_poisoning = __page_init_poisoning;
313 
314 	return 1;
315 }
316 __setup("vm_debug", setup_vm_debug);
317 
318 void page_init_poison(struct page *page, size_t size)
319 {
320 	if (page_init_poisoning)
321 		memset(page, PAGE_POISON_PATTERN, size);
322 }
323 EXPORT_SYMBOL_GPL(page_init_poison);
324 #endif		/* CONFIG_DEBUG_VM */
325