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         "contig_range",
  28         "longterm_pin",
  29         "demotion",
  30 };
  31
  32 const struct trace_print_flags pageflag_names[] = {
  33         __def_pageflag_names,
  34         {0, NULL}
  35 };
  36
  37 const struct trace_print_flags gfpflag_names[] = {
  38         __def_gfpflag_names,
  39         {0, NULL}
  40 };
  41
  42 const struct trace_print_flags vmaflag_names[] = {
  43         __def_vmaflag_names,
  44         {0, NULL}
  45 };
  46
  47 static void __dump_page(struct page *page)
  48 {
  49         struct page *head = compound_head(page);
  50         struct address_space *mapping;
  51         bool compound = PageCompound(page);
  52         /*
  53          * Accessing the pageblock without the zone lock. It could change to
  54          * "isolate" again in the meantime, but since we are just dumping the
  55          * state for debugging, it should be fine to accept a bit of
  56          * inaccuracy here due to racing.
  57          */
  58         bool page_cma = is_migrate_cma_page(page);
  59         int mapcount;
  60         char *type = "";
  61
  62         if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) {
  63                 /*
  64                  * Corrupt page, so we cannot call page_mapping. Instead, do a
  65                  * safe subset of the steps that page_mapping() does. Caution:
  66                  * this will be misleading for tail pages, PageSwapCache pages,
  67                  * and potentially other situations. (See the page_mapping()
  68                  * implementation for what's missing here.)
  69                  */
  70                 unsigned long tmp = (unsigned long)page->mapping;
  71
  72                 if (tmp & PAGE_MAPPING_ANON)
  73                         mapping = NULL;
  74                 else
  75                         mapping = (void *)(tmp & ~PAGE_MAPPING_FLAGS);
  76                 head = page;
  77                 compound = false;
  78         } else {
  79                 mapping = page_mapping(page);
  80         }
  81
  82         /*
  83          * Avoid VM_BUG_ON() in page_mapcount().
  84          * page->_mapcount space in struct page is used by sl[aou]b pages to
  85          * encode own info.
  86          */
  87         mapcount = PageSlab(head) ? 0 : page_mapcount(page);
  88
  89         pr_warn("page:%p refcount:%d mapcount:%d mapping:%p index:%#lx pfn:%#lx\n",
  90                         page, page_ref_count(head), mapcount, mapping,
  91                         page_to_pgoff(page), page_to_pfn(page));
  92         if (compound) {
  93                 if (hpage_pincount_available(page)) {
  94                         pr_warn("head:%p order:%u compound_mapcount:%d compound_pincount:%d\n",
  95                                         head, compound_order(head),
  96                                         head_compound_mapcount(head),
  97                                         head_compound_pincount(head));
  98                 } else {
  99                         pr_warn("head:%p order:%u compound_mapcount:%d\n",
 100                                         head, compound_order(head),
 101                                         head_compound_mapcount(head));
 102                 }
 103         }
 104
 105 #ifdef CONFIG_MEMCG
 106         if (head->memcg_data)
 107                 pr_warn("memcg:%lx\n", head->memcg_data);
 108 #endif
 109         if (PageKsm(page))
 110                 type = "ksm ";
 111         else if (PageAnon(page))
 112                 type = "anon ";
 113         else if (mapping) {
 114                 struct inode *host;
 115                 const struct address_space_operations *a_ops;
 116                 struct hlist_node *dentry_first;
 117                 struct dentry *dentry_ptr;
 118                 struct dentry dentry;
 119                 unsigned long ino;
 120
 121                 /*
 122                  * mapping can be invalid pointer and we don't want to crash
 123                  * accessing it, so probe everything depending on it carefully
 124                  */
 125                 if (get_kernel_nofault(host, &mapping->host) ||
 126                     get_kernel_nofault(a_ops, &mapping->a_ops)) {
 127                         pr_warn("failed to read mapping contents, not a valid kernel address?\n");
 128                         goto out_mapping;
 129                 }
 130
 131                 if (!host) {
 132                         pr_warn("aops:%ps\n", a_ops);
 133                         goto out_mapping;
 134                 }
 135
 136                 if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
 137                     get_kernel_nofault(ino, &host->i_ino)) {
 138                         pr_warn("aops:%ps with invalid host inode %px\n",
 139                                         a_ops, host);
 140                         goto out_mapping;
 141                 }
 142
 143                 if (!dentry_first) {
 144                         pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
 145                         goto out_mapping;
 146                 }
 147
 148                 dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
 149                 if (get_kernel_nofault(dentry, dentry_ptr)) {
 150                         pr_warn("aops:%ps ino:%lx with invalid dentry %px\n",
 151                                         a_ops, ino, dentry_ptr);
 152                 } else {
 153                         /*
 154                          * if dentry is corrupted, the %pd handler may still
 155                          * crash, but it's unlikely that we reach here with a
 156                          * corrupted struct page
 157                          */
 158                         pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n",
 159                                         a_ops, ino, &dentry);
 160                 }
 161         }
 162 out_mapping:
 163         BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
 164
 165         pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags, &head->flags,
 166                 page_cma ? " CMA" : "");
 167         print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
 168                         sizeof(unsigned long), page,
 169                         sizeof(struct page), false);
 170         if (head != page)
 171                 print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
 172                         sizeof(unsigned long), head,
 173                         sizeof(struct page), false);
 174 }
 175
 176 void dump_page(struct page *page, const char *reason)
 177 {
 178         if (PagePoisoned(page))
 179                 pr_warn("page:%p is uninitialized and poisoned", page);
 180         else
 181                 __dump_page(page);
 182         if (reason)
 183                 pr_warn("page dumped because: %s\n", reason);
 184         dump_page_owner(page);
 185 }
 186 EXPORT_SYMBOL(dump_page);
 187
 188 #ifdef CONFIG_DEBUG_VM
 189
 190 void dump_vma(const struct vm_area_struct *vma)
 191 {
 192         pr_emerg("vma %px start %px end %px\n"
 193                 "next %px prev %px mm %px\n"
 194                 "prot %lx anon_vma %px vm_ops %px\n"
 195                 "pgoff %lx file %px private_data %px\n"
 196                 "flags: %#lx(%pGv)\n",
 197                 vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
 198                 vma->vm_prev, vma->vm_mm,
 199                 (unsigned long)pgprot_val(vma->vm_page_prot),
 200                 vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
 201                 vma->vm_file, vma->vm_private_data,
 202                 vma->vm_flags, &vma->vm_flags);
 203 }
 204 EXPORT_SYMBOL(dump_vma);
 205
 206 void dump_mm(const struct mm_struct *mm)
 207 {
 208         pr_emerg("mm %px mmap %px seqnum %llu task_size %lu\n"
 209 #ifdef CONFIG_MMU
 210                 "get_unmapped_area %px\n"
 211 #endif
 212                 "mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
 213                 "pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
 214                 "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
 215                 "pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
 216                 "start_code %lx end_code %lx start_data %lx end_data %lx\n"
 217                 "start_brk %lx brk %lx start_stack %lx\n"
 218                 "arg_start %lx arg_end %lx env_start %lx env_end %lx\n"
 219                 "binfmt %px flags %lx core_state %px\n"
 220 #ifdef CONFIG_AIO
 221                 "ioctx_table %px\n"
 222 #endif
 223 #ifdef CONFIG_MEMCG
 224                 "owner %px "
 225 #endif
 226                 "exe_file %px\n"
 227 #ifdef CONFIG_MMU_NOTIFIER
 228                 "notifier_subscriptions %px\n"
 229 #endif
 230 #ifdef CONFIG_NUMA_BALANCING
 231                 "numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n"
 232 #endif
 233                 "tlb_flush_pending %d\n"
 234                 "def_flags: %#lx(%pGv)\n",
 235
 236                 mm, mm->mmap, (long long) mm->vmacache_seqnum, mm->task_size,
 237 #ifdef CONFIG_MMU
 238                 mm->get_unmapped_area,
 239 #endif
 240                 mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
 241                 mm->pgd, atomic_read(&mm->mm_users),
 242                 atomic_read(&mm->mm_count),
 243                 mm_pgtables_bytes(mm),
 244                 mm->map_count,
 245                 mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm,
 246                 (u64)atomic64_read(&mm->pinned_vm),
 247                 mm->data_vm, mm->exec_vm, mm->stack_vm,
 248                 mm->start_code, mm->end_code, mm->start_data, mm->end_data,
 249                 mm->start_brk, mm->brk, mm->start_stack,
 250                 mm->arg_start, mm->arg_end, mm->env_start, mm->env_end,
 251                 mm->binfmt, mm->flags, mm->core_state,
 252 #ifdef CONFIG_AIO
 253                 mm->ioctx_table,
 254 #endif
 255 #ifdef CONFIG_MEMCG
 256                 mm->owner,
 257 #endif
 258                 mm->exe_file,
 259 #ifdef CONFIG_MMU_NOTIFIER
 260                 mm->notifier_subscriptions,
 261 #endif
 262 #ifdef CONFIG_NUMA_BALANCING
 263                 mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq,
 264 #endif
 265                 atomic_read(&mm->tlb_flush_pending),
 266                 mm->def_flags, &mm->def_flags
 267         );
 268 }
 269
 270 static bool page_init_poisoning __read_mostly = true;
 271
 272 static int __init setup_vm_debug(char *str)
 273 {
 274         bool __page_init_poisoning = true;
 275
 276         /*
 277          * Calling vm_debug with no arguments is equivalent to requesting
 278          * to enable all debugging options we can control.
 279          */
 280         if (*str++ != '=' || !*str)
 281                 goto out;
 282
 283         __page_init_poisoning = false;
 284         if (*str == '-')
 285                 goto out;
 286
 287         while (*str) {
 288                 switch (tolower(*str)) {
 289                 case'p':
 290                         __page_init_poisoning = true;
 291                         break;
 292                 default:
 293                         pr_err("vm_debug option '%c' unknown. skipped\n",
 294                                *str);
 295                 }
 296
 297                 str++;
 298         }
 299 out:
 300         if (page_init_poisoning && !__page_init_poisoning)
 301                 pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n");
 302
 303         page_init_poisoning = __page_init_poisoning;
 304
 305         return 1;
 306 }
 307 __setup("vm_debug", setup_vm_debug);
 308
 309 void page_init_poison(struct page *page, size_t size)
 310 {
 311         if (page_init_poisoning)
 312                 memset(page, PAGE_POISON_PATTERN, size);
 313 }
 314 EXPORT_SYMBOL_GPL(page_init_poison);
 315 #endif          /* CONFIG_DEBUG_VM */