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 } 113 114 #ifdef CONFIG_MEMCG 115 if (head->memcg_data) 116 pr_warn("memcg:%lx\n", head->memcg_data); 117 #endif 118 if (PageKsm(page)) 119 type = "ksm "; 120 else if (PageAnon(page)) 121 type = "anon "; 122 else if (mapping) { 123 struct inode *host; 124 const struct address_space_operations *a_ops; 125 struct hlist_node *dentry_first; 126 struct dentry *dentry_ptr; 127 struct dentry dentry; 128 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 if (get_kernel_nofault(host, &mapping->host) || 135 get_kernel_nofault(a_ops, &mapping->a_ops)) { 136 pr_warn("failed to read mapping contents, not a valid kernel address?\n"); 137 goto out_mapping; 138 } 139 140 if (!host) { 141 pr_warn("aops:%ps\n", a_ops); 142 goto out_mapping; 143 } 144 145 if (get_kernel_nofault(dentry_first, &host->i_dentry.first) || 146 get_kernel_nofault(ino, &host->i_ino)) { 147 pr_warn("aops:%ps with invalid host inode %px\n", 148 a_ops, host); 149 goto out_mapping; 150 } 151 152 if (!dentry_first) { 153 pr_warn("aops:%ps ino:%lx\n", a_ops, ino); 154 goto out_mapping; 155 } 156 157 dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias); 158 if (get_kernel_nofault(dentry, dentry_ptr)) { 159 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 pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n", 168 a_ops, ino, &dentry); 169 } 170 } 171 out_mapping: 172 BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1); 173 174 pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags, &head->flags, 175 page_cma ? " CMA" : ""); 176 177 hex_only: 178 print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32, 179 sizeof(unsigned long), page, 180 sizeof(struct page), false); 181 if (head != page) 182 print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32, 183 sizeof(unsigned long), head, 184 sizeof(struct page), false); 185 186 if (reason) 187 pr_warn("page dumped because: %s\n", reason); 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