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