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                 if (mapping->host && mapping->host->i_dentry.first) {
 114                         struct dentry *dentry;
 115                         dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
 116                         pr_warn("%ps name:\"%pd\"\n", mapping->a_ops, dentry);
 117                 } else
 118                         pr_warn("%ps\n", mapping->a_ops);
 119         }
 120         BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
 121
 122         pr_warn("%sflags: %#lx(%pGp)%s\n", type, page->flags, &page->flags,
 123                 page_cma ? " CMA" : "");
 124
 125 hex_only:
 126         print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
 127                         sizeof(unsigned long), page,
 128                         sizeof(struct page), false);
 129         if (head != page)
 130                 print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
 131                         sizeof(unsigned long), head,
 132                         sizeof(struct page), false);
 133
 134         if (reason)
 135                 pr_warn("page dumped because: %s\n", reason);
 136
 137 #ifdef CONFIG_MEMCG
 138         if (!page_poisoned && page->mem_cgroup)
 139                 pr_warn("page->mem_cgroup:%px\n", page->mem_cgroup);
 140 #endif
 141 }
 142
 143 void dump_page(struct page *page, const char *reason)
 144 {
 145         __dump_page(page, reason);
 146         dump_page_owner(page);
 147 }
 148 EXPORT_SYMBOL(dump_page);
 149
 150 #ifdef CONFIG_DEBUG_VM
 151
 152 void dump_vma(const struct vm_area_struct *vma)
 153 {
 154         pr_emerg("vma %px start %px end %px\n"
 155                 "next %px prev %px mm %px\n"
 156                 "prot %lx anon_vma %px vm_ops %px\n"
 157                 "pgoff %lx file %px private_data %px\n"
 158                 "flags: %#lx(%pGv)\n",
 159                 vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
 160                 vma->vm_prev, vma->vm_mm,
 161                 (unsigned long)pgprot_val(vma->vm_page_prot),
 162                 vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
 163                 vma->vm_file, vma->vm_private_data,
 164                 vma->vm_flags, &vma->vm_flags);
 165 }
 166 EXPORT_SYMBOL(dump_vma);
 167
 168 void dump_mm(const struct mm_struct *mm)
 169 {
 170         pr_emerg("mm %px mmap %px seqnum %llu task_size %lu\n"
 171 #ifdef CONFIG_MMU
 172                 "get_unmapped_area %px\n"
 173 #endif
 174                 "mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
 175                 "pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
 176                 "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
 177                 "pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
 178                 "start_code %lx end_code %lx start_data %lx end_data %lx\n"
 179                 "start_brk %lx brk %lx start_stack %lx\n"
 180                 "arg_start %lx arg_end %lx env_start %lx env_end %lx\n"
 181                 "binfmt %px flags %lx core_state %px\n"
 182 #ifdef CONFIG_AIO
 183                 "ioctx_table %px\n"
 184 #endif
 185 #ifdef CONFIG_MEMCG
 186                 "owner %px "
 187 #endif
 188                 "exe_file %px\n"
 189 #ifdef CONFIG_MMU_NOTIFIER
 190                 "notifier_subscriptions %px\n"
 191 #endif
 192 #ifdef CONFIG_NUMA_BALANCING
 193                 "numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n"
 194 #endif
 195                 "tlb_flush_pending %d\n"
 196                 "def_flags: %#lx(%pGv)\n",
 197
 198                 mm, mm->mmap, (long long) mm->vmacache_seqnum, mm->task_size,
 199 #ifdef CONFIG_MMU
 200                 mm->get_unmapped_area,
 201 #endif
 202                 mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
 203                 mm->pgd, atomic_read(&mm->mm_users),
 204                 atomic_read(&mm->mm_count),
 205                 mm_pgtables_bytes(mm),
 206                 mm->map_count,
 207                 mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm,
 208                 (u64)atomic64_read(&mm->pinned_vm),
 209                 mm->data_vm, mm->exec_vm, mm->stack_vm,
 210                 mm->start_code, mm->end_code, mm->start_data, mm->end_data,
 211                 mm->start_brk, mm->brk, mm->start_stack,
 212                 mm->arg_start, mm->arg_end, mm->env_start, mm->env_end,
 213                 mm->binfmt, mm->flags, mm->core_state,
 214 #ifdef CONFIG_AIO
 215                 mm->ioctx_table,
 216 #endif
 217 #ifdef CONFIG_MEMCG
 218                 mm->owner,
 219 #endif
 220                 mm->exe_file,
 221 #ifdef CONFIG_MMU_NOTIFIER
 222                 mm->notifier_subscriptions,
 223 #endif
 224 #ifdef CONFIG_NUMA_BALANCING
 225                 mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq,
 226 #endif
 227                 atomic_read(&mm->tlb_flush_pending),
 228                 mm->def_flags, &mm->def_flags
 229         );
 230 }
 231
 232 static bool page_init_poisoning __read_mostly = true;
 233
 234 static int __init setup_vm_debug(char *str)
 235 {
 236         bool __page_init_poisoning = true;
 237
 238         /*
 239          * Calling vm_debug with no arguments is equivalent to requesting
 240          * to enable all debugging options we can control.
 241          */
 242         if (*str++ != '=' || !*str)
 243                 goto out;
 244
 245         __page_init_poisoning = false;
 246         if (*str == '-')
 247                 goto out;
 248
 249         while (*str) {
 250                 switch (tolower(*str)) {
 251                 case'p':
 252                         __page_init_poisoning = true;
 253                         break;
 254                 default:
 255                         pr_err("vm_debug option '%c' unknown. skipped\n",
 256                                *str);
 257                 }
 258
 259                 str++;
 260         }
 261 out:
 262         if (page_init_poisoning && !__page_init_poisoning)
 263                 pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n");
 264
 265         page_init_poisoning = __page_init_poisoning;
 266
 267         return 1;
 268 }
 269 __setup("vm_debug", setup_vm_debug);
 270
 271 void page_init_poison(struct page *page, size_t size)
 272 {
 273         if (page_init_poisoning)
 274                 memset(page, PAGE_POISON_PATTERN, size);
 275 }
 276 EXPORT_SYMBOL_GPL(page_init_poison);
 277 #endif          /* CONFIG_DEBUG_VM */