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 #include <trace/events/migrate.h> 20 21 /* 22 * Define EM() and EMe() so that MIGRATE_REASON from trace/events/migrate.h can 23 * be used to populate migrate_reason_names[]. 24 */ 25 #undef EM 26 #undef EMe 27 #define EM(a, b) b, 28 #define EMe(a, b) b 29 30 const char *migrate_reason_names[MR_TYPES] = { 31 MIGRATE_REASON 32 }; 33 34 const struct trace_print_flags pageflag_names[] = { 35 __def_pageflag_names, 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 49 static void __dump_page(struct page *page) 50 { 51 struct page *head = compound_head(page); 52 struct address_space *mapping; 53 bool compound = PageCompound(page); 54 /* 55 * Accessing the pageblock without the zone lock. It could change to 56 * "isolate" again in the meantime, but since we are just dumping the 57 * state for debugging, it should be fine to accept a bit of 58 * inaccuracy here due to racing. 59 */ 60 bool page_cma = is_migrate_cma_page(page); 61 int mapcount; 62 char *type = ""; 63 64 if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) { 65 /* 66 * Corrupt page, so we cannot call page_mapping. Instead, do a 67 * safe subset of the steps that page_mapping() does. Caution: 68 * this will be misleading for tail pages, PageSwapCache pages, 69 * and potentially other situations. (See the page_mapping() 70 * implementation for what's missing here.) 71 */ 72 unsigned long tmp = (unsigned long)page->mapping; 73 74 if (tmp & PAGE_MAPPING_ANON) 75 mapping = NULL; 76 else 77 mapping = (void *)(tmp & ~PAGE_MAPPING_FLAGS); 78 head = page; 79 compound = false; 80 } else { 81 mapping = page_mapping(page); 82 } 83 84 /* 85 * Avoid VM_BUG_ON() in page_mapcount(). 86 * page->_mapcount space in struct page is used by sl[aou]b pages to 87 * encode own info. 88 */ 89 mapcount = PageSlab(head) ? 0 : page_mapcount(page); 90 91 pr_warn("page:%p refcount:%d mapcount:%d mapping:%p index:%#lx pfn:%#lx\n", 92 page, page_ref_count(head), mapcount, mapping, 93 page_to_pgoff(page), page_to_pfn(page)); 94 if (compound) { 95 if (hpage_pincount_available(page)) { 96 pr_warn("head:%p order:%u compound_mapcount:%d compound_pincount:%d\n", 97 head, compound_order(head), 98 head_compound_mapcount(head), 99 head_compound_pincount(head)); 100 } else { 101 pr_warn("head:%p order:%u compound_mapcount:%d\n", 102 head, compound_order(head), 103 head_compound_mapcount(head)); 104 } 105 } 106 107 #ifdef CONFIG_MEMCG 108 if (head->memcg_data) 109 pr_warn("memcg:%lx\n", head->memcg_data); 110 #endif 111 if (PageKsm(page)) 112 type = "ksm "; 113 else if (PageAnon(page)) 114 type = "anon "; 115 else if (mapping) { 116 struct inode *host; 117 const struct address_space_operations *a_ops; 118 struct hlist_node *dentry_first; 119 struct dentry *dentry_ptr; 120 struct dentry dentry; 121 unsigned long ino; 122 123 /* 124 * mapping can be invalid pointer and we don't want to crash 125 * accessing it, so probe everything depending on it carefully 126 */ 127 if (get_kernel_nofault(host, &mapping->host) || 128 get_kernel_nofault(a_ops, &mapping->a_ops)) { 129 pr_warn("failed to read mapping contents, not a valid kernel address?\n"); 130 goto out_mapping; 131 } 132 133 if (!host) { 134 pr_warn("aops:%ps\n", a_ops); 135 goto out_mapping; 136 } 137 138 if (get_kernel_nofault(dentry_first, &host->i_dentry.first) || 139 get_kernel_nofault(ino, &host->i_ino)) { 140 pr_warn("aops:%ps with invalid host inode %px\n", 141 a_ops, host); 142 goto out_mapping; 143 } 144 145 if (!dentry_first) { 146 pr_warn("aops:%ps ino:%lx\n", a_ops, ino); 147 goto out_mapping; 148 } 149 150 dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias); 151 if (get_kernel_nofault(dentry, dentry_ptr)) { 152 pr_warn("aops:%ps ino:%lx with invalid dentry %px\n", 153 a_ops, ino, dentry_ptr); 154 } else { 155 /* 156 * if dentry is corrupted, the %pd handler may still 157 * crash, but it's unlikely that we reach here with a 158 * corrupted struct page 159 */ 160 pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n", 161 a_ops, ino, &dentry); 162 } 163 } 164 out_mapping: 165 BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1); 166 167 pr_warn("%sflags: %pGp%s\n", type, &head->flags, 168 page_cma ? " CMA" : ""); 169 print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32, 170 sizeof(unsigned long), page, 171 sizeof(struct page), false); 172 if (head != page) 173 print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32, 174 sizeof(unsigned long), head, 175 sizeof(struct page), false); 176 } 177 178 void dump_page(struct page *page, const char *reason) 179 { 180 if (PagePoisoned(page)) 181 pr_warn("page:%p is uninitialized and poisoned", page); 182 else 183 __dump_page(page); 184 if (reason) 185 pr_warn("page dumped because: %s\n", reason); 186 dump_page_owner(page); 187 } 188 EXPORT_SYMBOL(dump_page); 189 190 #ifdef CONFIG_DEBUG_VM 191 192 void dump_vma(const struct vm_area_struct *vma) 193 { 194 pr_emerg("vma %px start %px end %px\n" 195 "next %px prev %px mm %px\n" 196 "prot %lx anon_vma %px vm_ops %px\n" 197 "pgoff %lx file %px private_data %px\n" 198 "flags: %#lx(%pGv)\n", 199 vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next, 200 vma->vm_prev, vma->vm_mm, 201 (unsigned long)pgprot_val(vma->vm_page_prot), 202 vma->anon_vma, vma->vm_ops, vma->vm_pgoff, 203 vma->vm_file, vma->vm_private_data, 204 vma->vm_flags, &vma->vm_flags); 205 } 206 EXPORT_SYMBOL(dump_vma); 207 208 void dump_mm(const struct mm_struct *mm) 209 { 210 pr_emerg("mm %px mmap %px seqnum %llu task_size %lu\n" 211 #ifdef CONFIG_MMU 212 "get_unmapped_area %px\n" 213 #endif 214 "mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n" 215 "pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n" 216 "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n" 217 "pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n" 218 "start_code %lx end_code %lx start_data %lx end_data %lx\n" 219 "start_brk %lx brk %lx start_stack %lx\n" 220 "arg_start %lx arg_end %lx env_start %lx env_end %lx\n" 221 "binfmt %px flags %lx\n" 222 #ifdef CONFIG_AIO 223 "ioctx_table %px\n" 224 #endif 225 #ifdef CONFIG_MEMCG 226 "owner %px " 227 #endif 228 "exe_file %px\n" 229 #ifdef CONFIG_MMU_NOTIFIER 230 "notifier_subscriptions %px\n" 231 #endif 232 #ifdef CONFIG_NUMA_BALANCING 233 "numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n" 234 #endif 235 "tlb_flush_pending %d\n" 236 "def_flags: %#lx(%pGv)\n", 237 238 mm, mm->mmap, (long long) mm->vmacache_seqnum, mm->task_size, 239 #ifdef CONFIG_MMU 240 mm->get_unmapped_area, 241 #endif 242 mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end, 243 mm->pgd, atomic_read(&mm->mm_users), 244 atomic_read(&mm->mm_count), 245 mm_pgtables_bytes(mm), 246 mm->map_count, 247 mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm, 248 (u64)atomic64_read(&mm->pinned_vm), 249 mm->data_vm, mm->exec_vm, mm->stack_vm, 250 mm->start_code, mm->end_code, mm->start_data, mm->end_data, 251 mm->start_brk, mm->brk, mm->start_stack, 252 mm->arg_start, mm->arg_end, mm->env_start, mm->env_end, 253 mm->binfmt, mm->flags, 254 #ifdef CONFIG_AIO 255 mm->ioctx_table, 256 #endif 257 #ifdef CONFIG_MEMCG 258 mm->owner, 259 #endif 260 mm->exe_file, 261 #ifdef CONFIG_MMU_NOTIFIER 262 mm->notifier_subscriptions, 263 #endif 264 #ifdef CONFIG_NUMA_BALANCING 265 mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq, 266 #endif 267 atomic_read(&mm->tlb_flush_pending), 268 mm->def_flags, &mm->def_flags 269 ); 270 } 271 272 static bool page_init_poisoning __read_mostly = true; 273 274 static int __init setup_vm_debug(char *str) 275 { 276 bool __page_init_poisoning = true; 277 278 /* 279 * Calling vm_debug with no arguments is equivalent to requesting 280 * to enable all debugging options we can control. 281 */ 282 if (*str++ != '=' || !*str) 283 goto out; 284 285 __page_init_poisoning = false; 286 if (*str == '-') 287 goto out; 288 289 while (*str) { 290 switch (tolower(*str)) { 291 case'p': 292 __page_init_poisoning = true; 293 break; 294 default: 295 pr_err("vm_debug option '%c' unknown. skipped\n", 296 *str); 297 } 298 299 str++; 300 } 301 out: 302 if (page_init_poisoning && !__page_init_poisoning) 303 pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n"); 304 305 page_init_poisoning = __page_init_poisoning; 306 307 return 1; 308 } 309 __setup("vm_debug", setup_vm_debug); 310 311 void page_init_poison(struct page *page, size_t size) 312 { 313 if (page_init_poisoning) 314 memset(page, PAGE_POISON_PATTERN, size); 315 } 316 EXPORT_SYMBOL_GPL(page_init_poison); 317 #endif /* CONFIG_DEBUG_VM */ 318