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 #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 */