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                 /* Corrupt page, cannot call page_mapping */
  73                 mapping = page->mapping;
  74                 head = page;
  75                 compound = false;
  76         } else {
  77                 mapping = page_mapping(page);
  78         }
  79
  80         /*
  81          * Avoid VM_BUG_ON() in page_mapcount().
  82          * page->_mapcount space in struct page is used by sl[aou]b pages to
  83          * encode own info.
  84          */
  85         mapcount = PageSlab(head) ? 0 : page_mapcount(page);
  86
  87         if (compound)
  88                 if (hpage_pincount_available(page)) {
  89                         pr_warn("page:%px refcount:%d mapcount:%d mapping:%p "
  90                                 "index:%#lx head:%px order:%u "
  91                                 "compound_mapcount:%d compound_pincount:%d\n",
  92                                 page, page_ref_count(head), mapcount,
  93                                 mapping, page_to_pgoff(page), head,
  94                                 compound_order(head), compound_mapcount(page),
  95                                 compound_pincount(page));
  96                 } else {
  97                         pr_warn("page:%px refcount:%d mapcount:%d mapping:%p "
  98                                 "index:%#lx head:%px order:%u "
  99                                 "compound_mapcount:%d\n",
 100                                 page, page_ref_count(head), mapcount,
 101                                 mapping, page_to_pgoff(page), head,
 102                                 compound_order(head), compound_mapcount(page));
 103                 }
 104         else
 105                 pr_warn("page:%px refcount:%d mapcount:%d mapping:%p index:%#lx\n",
 106                         page, page_ref_count(page), mapcount,
 107                         mapping, page_to_pgoff(page));
 108         if (PageKsm(page))
 109                 type = "ksm ";
 110         else if (PageAnon(page))
 111                 type = "anon ";
 112         else if (mapping) {
 113                 const struct inode *host;
 114                 const struct address_space_operations *a_ops;
 115                 const struct hlist_node *dentry_first;
 116                 const struct dentry *dentry_ptr;
 117                 struct dentry dentry;
 118
 119                 /*
 120                  * mapping can be invalid pointer and we don't want to crash
 121                  * accessing it, so probe everything depending on it carefully
 122                  */
 123                 if (probe_kernel_read(&host, &mapping->host,
 124                                         sizeof(struct inode *)) ||
 125                     probe_kernel_read(&a_ops, &mapping->a_ops,
 126                                 sizeof(struct address_space_operations *))) {
 127                         pr_warn("failed to read mapping->host or a_ops, mapping not a valid kernel address?\n");
 128                         goto out_mapping;
 129                 }
 130
 131                 if (!host) {
 132                         pr_warn("mapping->a_ops:%ps\n", a_ops);
 133                         goto out_mapping;
 134                 }
 135
 136                 if (probe_kernel_read(&dentry_first,
 137                         &host->i_dentry.first, sizeof(struct hlist_node *))) {
 138                         pr_warn("mapping->a_ops:%ps with invalid mapping->host inode address %px\n",
 139                                 a_ops, host);
 140                         goto out_mapping;
 141                 }
 142
 143                 if (!dentry_first) {
 144                         pr_warn("mapping->a_ops:%ps\n", a_ops);
 145                         goto out_mapping;
 146                 }
 147
 148                 dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
 149                 if (probe_kernel_read(&dentry, dentry_ptr,
 150                                                         sizeof(struct dentry))) {
 151                         pr_warn("mapping->aops:%ps with invalid mapping->host->i_dentry.first %px\n",
 152                                 a_ops, dentry_ptr);
 153                 } else {
 154                         /*
 155                          * if dentry is corrupted, the %pd handler may still
 156                          * crash, but it's unlikely that we reach here with a
 157                          * corrupted struct page
 158                          */
 159                         pr_warn("mapping->aops:%ps dentry name:\"%pd\"\n",
 160                                                                 a_ops, &dentry);
 161                 }
 162         }
 163 out_mapping:
 164         BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
 165
 166         pr_warn("%sflags: %#lx(%pGp)%s\n", type, page->flags, &page->flags,
 167                 page_cma ? " CMA" : "");
 168
 169 hex_only:
 170         print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
 171                         sizeof(unsigned long), page,
 172                         sizeof(struct page), false);
 173         if (head != page)
 174                 print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
 175                         sizeof(unsigned long), head,
 176                         sizeof(struct page), false);
 177
 178         if (reason)
 179                 pr_warn("page dumped because: %s\n", reason);
 180
 181 #ifdef CONFIG_MEMCG
 182         if (!page_poisoned && page->mem_cgroup)
 183                 pr_warn("page->mem_cgroup:%px\n", page->mem_cgroup);
 184 #endif
 185 }
 186
 187 void dump_page(struct page *page, const char *reason)
 188 {
 189         __dump_page(page, reason);
 190         dump_page_owner(page);
 191 }
 192 EXPORT_SYMBOL(dump_page);
 193
 194 #ifdef CONFIG_DEBUG_VM
 195
 196 void dump_vma(const struct vm_area_struct *vma)
 197 {
 198         pr_emerg("vma %px start %px end %px\n"
 199                 "next %px prev %px mm %px\n"
 200                 "prot %lx anon_vma %px vm_ops %px\n"
 201                 "pgoff %lx file %px private_data %px\n"
 202                 "flags: %#lx(%pGv)\n",
 203                 vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
 204                 vma->vm_prev, vma->vm_mm,
 205                 (unsigned long)pgprot_val(vma->vm_page_prot),
 206                 vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
 207                 vma->vm_file, vma->vm_private_data,
 208                 vma->vm_flags, &vma->vm_flags);
 209 }
 210 EXPORT_SYMBOL(dump_vma);
 211
 212 void dump_mm(const struct mm_struct *mm)
 213 {
 214         pr_emerg("mm %px mmap %px seqnum %llu task_size %lu\n"
 215 #ifdef CONFIG_MMU
 216                 "get_unmapped_area %px\n"
 217 #endif
 218                 "mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
 219                 "pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
 220                 "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
 221                 "pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
 222                 "start_code %lx end_code %lx start_data %lx end_data %lx\n"
 223                 "start_brk %lx brk %lx start_stack %lx\n"
 224                 "arg_start %lx arg_end %lx env_start %lx env_end %lx\n"
 225                 "binfmt %px flags %lx core_state %px\n"
 226 #ifdef CONFIG_AIO
 227                 "ioctx_table %px\n"
 228 #endif
 229 #ifdef CONFIG_MEMCG
 230                 "owner %px "
 231 #endif
 232                 "exe_file %px\n"
 233 #ifdef CONFIG_MMU_NOTIFIER
 234                 "notifier_subscriptions %px\n"
 235 #endif
 236 #ifdef CONFIG_NUMA_BALANCING
 237                 "numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n"
 238 #endif
 239                 "tlb_flush_pending %d\n"
 240                 "def_flags: %#lx(%pGv)\n",
 241
 242                 mm, mm->mmap, (long long) mm->vmacache_seqnum, mm->task_size,
 243 #ifdef CONFIG_MMU
 244                 mm->get_unmapped_area,
 245 #endif
 246                 mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
 247                 mm->pgd, atomic_read(&mm->mm_users),
 248                 atomic_read(&mm->mm_count),
 249                 mm_pgtables_bytes(mm),
 250                 mm->map_count,
 251                 mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm,
 252                 (u64)atomic64_read(&mm->pinned_vm),
 253                 mm->data_vm, mm->exec_vm, mm->stack_vm,
 254                 mm->start_code, mm->end_code, mm->start_data, mm->end_data,
 255                 mm->start_brk, mm->brk, mm->start_stack,
 256                 mm->arg_start, mm->arg_end, mm->env_start, mm->env_end,
 257                 mm->binfmt, mm->flags, mm->core_state,
 258 #ifdef CONFIG_AIO
 259                 mm->ioctx_table,
 260 #endif
 261 #ifdef CONFIG_MEMCG
 262                 mm->owner,
 263 #endif
 264                 mm->exe_file,
 265 #ifdef CONFIG_MMU_NOTIFIER
 266                 mm->notifier_subscriptions,
 267 #endif
 268 #ifdef CONFIG_NUMA_BALANCING
 269                 mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq,
 270 #endif
 271                 atomic_read(&mm->tlb_flush_pending),
 272                 mm->def_flags, &mm->def_flags
 273         );
 274 }
 275
 276 static bool page_init_poisoning __read_mostly = true;
 277
 278 static int __init setup_vm_debug(char *str)
 279 {
 280         bool __page_init_poisoning = true;
 281
 282         /*
 283          * Calling vm_debug with no arguments is equivalent to requesting
 284          * to enable all debugging options we can control.
 285          */
 286         if (*str++ != '=' || !*str)
 287                 goto out;
 288
 289         __page_init_poisoning = false;
 290         if (*str == '-')
 291                 goto out;
 292
 293         while (*str) {
 294                 switch (tolower(*str)) {
 295                 case'p':
 296                         __page_init_poisoning = true;
 297                         break;
 298                 default:
 299                         pr_err("vm_debug option '%c' unknown. skipped\n",
 300                                *str);
 301                 }
 302
 303                 str++;
 304         }
 305 out:
 306         if (page_init_poisoning && !__page_init_poisoning)
 307                 pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n");
 308
 309         page_init_poisoning = __page_init_poisoning;
 310
 311         return 1;
 312 }
 313 __setup("vm_debug", setup_vm_debug);
 314
 315 void page_init_poison(struct page *page, size_t size)
 316 {
 317         if (page_init_poisoning)
 318                 memset(page, PAGE_POISON_PATTERN, size);
 319 }
 320 EXPORT_SYMBOL_GPL(page_init_poison);
 321 #endif          /* CONFIG_DEBUG_VM */