mm/debug.c

   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_mapcount(head),
 106                                         head_pincount(head));
 107                 } else {
 108                         pr_warn("head:%p order:%u compound_mapcount:%d\n",
 109                                         head, compound_order(head),
 110                                         head_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
 124                 /*
 125                  * mapping can be invalid pointer and we don't want to crash
 126                  * accessing it, so probe everything depending on it carefully
 127                  */
 128                 if (get_kernel_nofault(host, &mapping->host) ||
 129                     get_kernel_nofault(a_ops, &mapping->a_ops)) {
 130                         pr_warn("failed to read mapping contents, not a valid kernel address?\n");
 131                         goto out_mapping;
 132                 }
 133
 134                 if (!host) {
 135                         pr_warn("aops:%ps\n", a_ops);
 136                         goto out_mapping;
 137                 }
 138
 139                 if (get_kernel_nofault(dentry_first, &host->i_dentry.first)) {
 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, host->i_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 with invalid dentry %px\n", a_ops,
 153                                         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, host->i_ino, &dentry);
 162                 }
 163         }
 164 out_mapping:
 165         BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
 166
 167         pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags, &head->flags,
 168                 page_cma ? " CMA" : "");
 169
 170 hex_only:
 171         print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
 172                         sizeof(unsigned long), page,
 173                         sizeof(struct page), false);
 174         if (head != page)
 175                 print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
 176                         sizeof(unsigned long), head,
 177                         sizeof(struct page), false);
 178
 179         if (reason)
 180                 pr_warn("page dumped because: %s\n", reason);
 181
 182 #ifdef CONFIG_MEMCG
 183         if (!page_poisoned && page->mem_cgroup)
 184                 pr_warn("page->mem_cgroup:%px\n", page->mem_cgroup);
 185 #endif
 186 }
 187
 188 void dump_page(struct page *page, const char *reason)
 189 {
 190         __dump_page(page, reason);
 191         dump_page_owner(page);
 192 }
 193 EXPORT_SYMBOL(dump_page);
 194
 195 #ifdef CONFIG_DEBUG_VM
 196
 197 void dump_vma(const struct vm_area_struct *vma)
 198 {
 199         pr_emerg("vma %px start %px end %px\n"
 200                 "next %px prev %px mm %px\n"
 201                 "prot %lx anon_vma %px vm_ops %px\n"
 202                 "pgoff %lx file %px private_data %px\n"
 203                 "flags: %#lx(%pGv)\n",
 204                 vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
 205                 vma->vm_prev, vma->vm_mm,
 206                 (unsigned long)pgprot_val(vma->vm_page_prot),
 207                 vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
 208                 vma->vm_file, vma->vm_private_data,
 209                 vma->vm_flags, &vma->vm_flags);
 210 }
 211 EXPORT_SYMBOL(dump_vma);
 212
 213 void dump_mm(const struct mm_struct *mm)
 214 {
 215         pr_emerg("mm %px mmap %px seqnum %llu task_size %lu\n"
 216 #ifdef CONFIG_MMU
 217                 "get_unmapped_area %px\n"
 218 #endif
 219                 "mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
 220                 "pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
 221                 "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
 222                 "pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
 223                 "start_code %lx end_code %lx start_data %lx end_data %lx\n"
 224                 "start_brk %lx brk %lx start_stack %lx\n"
 225                 "arg_start %lx arg_end %lx env_start %lx env_end %lx\n"
 226                 "binfmt %px flags %lx core_state %px\n"
 227 #ifdef CONFIG_AIO
 228                 "ioctx_table %px\n"
 229 #endif
 230 #ifdef CONFIG_MEMCG
 231                 "owner %px "
 232 #endif
 233                 "exe_file %px\n"
 234 #ifdef CONFIG_MMU_NOTIFIER
 235                 "notifier_subscriptions %px\n"
 236 #endif
 237 #ifdef CONFIG_NUMA_BALANCING
 238                 "numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n"
 239 #endif
 240                 "tlb_flush_pending %d\n"
 241                 "def_flags: %#lx(%pGv)\n",
 242
 243                 mm, mm->mmap, (long long) mm->vmacache_seqnum, mm->task_size,
 244 #ifdef CONFIG_MMU
 245                 mm->get_unmapped_area,
 246 #endif
 247                 mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
 248                 mm->pgd, atomic_read(&mm->mm_users),
 249                 atomic_read(&mm->mm_count),
 250                 mm_pgtables_bytes(mm),
 251                 mm->map_count,
 252                 mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm,
 253                 (u64)atomic64_read(&mm->pinned_vm),
 254                 mm->data_vm, mm->exec_vm, mm->stack_vm,
 255                 mm->start_code, mm->end_code, mm->start_data, mm->end_data,
 256                 mm->start_brk, mm->brk, mm->start_stack,
 257                 mm->arg_start, mm->arg_end, mm->env_start, mm->env_end,
 258                 mm->binfmt, mm->flags, mm->core_state,
 259 #ifdef CONFIG_AIO
 260                 mm->ioctx_table,
 261 #endif
 262 #ifdef CONFIG_MEMCG
 263                 mm->owner,
 264 #endif
 265                 mm->exe_file,
 266 #ifdef CONFIG_MMU_NOTIFIER
 267                 mm->notifier_subscriptions,
 268 #endif
 269 #ifdef CONFIG_NUMA_BALANCING
 270                 mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq,
 271 #endif
 272                 atomic_read(&mm->tlb_flush_pending),
 273                 mm->def_flags, &mm->def_flags
 274         );
 275 }
 276
 277 static bool page_init_poisoning __read_mostly = true;
 278
 279 static int __init setup_vm_debug(char *str)
 280 {
 281         bool __page_init_poisoning = true;
 282
 283         /*
 284          * Calling vm_debug with no arguments is equivalent to requesting
 285          * to enable all debugging options we can control.
 286          */
 287         if (*str++ != '=' || !*str)
 288                 goto out;
 289
 290         __page_init_poisoning = false;
 291         if (*str == '-')
 292                 goto out;
 293
 294         while (*str) {
 295                 switch (tolower(*str)) {
 296                 case'p':
 297                         __page_init_poisoning = true;
 298                         break;
 299                 default:
 300                         pr_err("vm_debug option '%c' unknown. skipped\n",
 301                                *str);
 302                 }
 303
 304                 str++;
 305         }
 306 out:
 307         if (page_init_poisoning && !__page_init_poisoning)
 308                 pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n");
 309
 310         page_init_poisoning = __page_init_poisoning;
 311
 312         return 1;
 313 }
 314 __setup("vm_debug", setup_vm_debug);
 315
 316 void page_init_poison(struct page *page, size_t size)
 317 {
 318         if (page_init_poisoning)
 319                 memset(page, PAGE_POISON_PATTERN, size);
 320 }
 321 EXPORT_SYMBOL_GPL(page_init_poison);
 322 #endif          /* CONFIG_DEBUG_VM */