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 folio *folio = page_folio(page);
  52         struct page *head = &folio->page;
  53         struct address_space *mapping;
  54         bool compound = PageCompound(page);
  55         /*
  56          * Accessing the pageblock without the zone lock. It could change to
  57          * "isolate" again in the meantime, but since we are just dumping the
  58          * state for debugging, it should be fine to accept a bit of
  59          * inaccuracy here due to racing.
  60          */
  61         bool page_cma = is_migrate_cma_page(page);
  62         int mapcount;
  63         char *type = "";
  64
  65         if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) {
  66                 /*
  67                  * Corrupt page, so we cannot call page_mapping. Instead, do a
  68                  * safe subset of the steps that page_mapping() does. Caution:
  69                  * this will be misleading for tail pages, PageSwapCache pages,
  70                  * and potentially other situations. (See the page_mapping()
  71                  * implementation for what's missing here.)
  72                  */
  73                 unsigned long tmp = (unsigned long)page->mapping;
  74
  75                 if (tmp & PAGE_MAPPING_ANON)
  76                         mapping = NULL;
  77                 else
  78                         mapping = (void *)(tmp & ~PAGE_MAPPING_FLAGS);
  79                 head = page;
  80                 folio = (struct folio *)page;
  81                 compound = false;
  82         } else {
  83                 mapping = page_mapping(page);
  84         }
  85
  86         /*
  87          * Avoid VM_BUG_ON() in page_mapcount().
  88          * page->_mapcount space in struct page is used by sl[aou]b pages to
  89          * encode own info.
  90          */
  91         mapcount = PageSlab(head) ? 0 : page_mapcount(page);
  92
  93         pr_warn("page:%p refcount:%d mapcount:%d mapping:%p index:%#lx pfn:%#lx\n",
  94                         page, page_ref_count(head), mapcount, mapping,
  95                         page_to_pgoff(page), page_to_pfn(page));
  96         if (compound) {
  97                 pr_warn("head:%p order:%u compound_mapcount:%d subpages_mapcount:%d compound_pincount:%d\n",
  98                                 head, compound_order(head),
  99                                 head_compound_mapcount(head),
 100                                 head_subpages_mapcount(head),
 101                                 head_compound_pincount(head));
 102         }
 103
 104 #ifdef CONFIG_MEMCG
 105         if (head->memcg_data)
 106                 pr_warn("memcg:%lx\n", head->memcg_data);
 107 #endif
 108         if (PageKsm(page))
 109                 type = "ksm ";
 110         else if (PageAnon(page))
 111                 type = "anon ";
 112         else if (mapping)
 113                 dump_mapping(mapping);
 114         BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
 115
 116         pr_warn("%sflags: %pGp%s\n", type, &head->flags,
 117                 page_cma ? " CMA" : "");
 118         print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
 119                         sizeof(unsigned long), page,
 120                         sizeof(struct page), false);
 121         if (head != page)
 122                 print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
 123                         sizeof(unsigned long), head,
 124                         sizeof(struct page), false);
 125 }
 126
 127 void dump_page(struct page *page, const char *reason)
 128 {
 129         if (PagePoisoned(page))
 130                 pr_warn("page:%p is uninitialized and poisoned", page);
 131         else
 132                 __dump_page(page);
 133         if (reason)
 134                 pr_warn("page dumped because: %s\n", reason);
 135         dump_page_owner(page);
 136 }
 137 EXPORT_SYMBOL(dump_page);
 138
 139 #ifdef CONFIG_DEBUG_VM
 140
 141 void dump_vma(const struct vm_area_struct *vma)
 142 {
 143         pr_emerg("vma %px start %px end %px mm %px\n"
 144                 "prot %lx anon_vma %px vm_ops %px\n"
 145                 "pgoff %lx file %px private_data %px\n"
 146                 "flags: %#lx(%pGv)\n",
 147                 vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_mm,
 148                 (unsigned long)pgprot_val(vma->vm_page_prot),
 149                 vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
 150                 vma->vm_file, vma->vm_private_data,
 151                 vma->vm_flags, &vma->vm_flags);
 152 }
 153 EXPORT_SYMBOL(dump_vma);
 154
 155 void dump_mm(const struct mm_struct *mm)
 156 {
 157         pr_emerg("mm %px task_size %lu\n"
 158 #ifdef CONFIG_MMU
 159                 "get_unmapped_area %px\n"
 160 #endif
 161                 "mmap_base %lu mmap_legacy_base %lu\n"
 162                 "pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
 163                 "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
 164                 "pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
 165                 "start_code %lx end_code %lx start_data %lx end_data %lx\n"
 166                 "start_brk %lx brk %lx start_stack %lx\n"
 167                 "arg_start %lx arg_end %lx env_start %lx env_end %lx\n"
 168                 "binfmt %px flags %lx\n"
 169 #ifdef CONFIG_AIO
 170                 "ioctx_table %px\n"
 171 #endif
 172 #ifdef CONFIG_MEMCG
 173                 "owner %px "
 174 #endif
 175                 "exe_file %px\n"
 176 #ifdef CONFIG_MMU_NOTIFIER
 177                 "notifier_subscriptions %px\n"
 178 #endif
 179 #ifdef CONFIG_NUMA_BALANCING
 180                 "numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n"
 181 #endif
 182                 "tlb_flush_pending %d\n"
 183                 "def_flags: %#lx(%pGv)\n",
 184
 185                 mm, mm->task_size,
 186 #ifdef CONFIG_MMU
 187                 mm->get_unmapped_area,
 188 #endif
 189                 mm->mmap_base, mm->mmap_legacy_base,
 190                 mm->pgd, atomic_read(&mm->mm_users),
 191                 atomic_read(&mm->mm_count),
 192                 mm_pgtables_bytes(mm),
 193                 mm->map_count,
 194                 mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm,
 195                 (u64)atomic64_read(&mm->pinned_vm),
 196                 mm->data_vm, mm->exec_vm, mm->stack_vm,
 197                 mm->start_code, mm->end_code, mm->start_data, mm->end_data,
 198                 mm->start_brk, mm->brk, mm->start_stack,
 199                 mm->arg_start, mm->arg_end, mm->env_start, mm->env_end,
 200                 mm->binfmt, mm->flags,
 201 #ifdef CONFIG_AIO
 202                 mm->ioctx_table,
 203 #endif
 204 #ifdef CONFIG_MEMCG
 205                 mm->owner,
 206 #endif
 207                 mm->exe_file,
 208 #ifdef CONFIG_MMU_NOTIFIER
 209                 mm->notifier_subscriptions,
 210 #endif
 211 #ifdef CONFIG_NUMA_BALANCING
 212                 mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq,
 213 #endif
 214                 atomic_read(&mm->tlb_flush_pending),
 215                 mm->def_flags, &mm->def_flags
 216         );
 217 }
 218
 219 static bool page_init_poisoning __read_mostly = true;
 220
 221 static int __init setup_vm_debug(char *str)
 222 {
 223         bool __page_init_poisoning = true;
 224
 225         /*
 226          * Calling vm_debug with no arguments is equivalent to requesting
 227          * to enable all debugging options we can control.
 228          */
 229         if (*str++ != '=' || !*str)
 230                 goto out;
 231
 232         __page_init_poisoning = false;
 233         if (*str == '-')
 234                 goto out;
 235
 236         while (*str) {
 237                 switch (tolower(*str)) {
 238                 case'p':
 239                         __page_init_poisoning = true;
 240                         break;
 241                 default:
 242                         pr_err("vm_debug option '%c' unknown. skipped\n",
 243                                *str);
 244                 }
 245
 246                 str++;
 247         }
 248 out:
 249         if (page_init_poisoning && !__page_init_poisoning)
 250                 pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n");
 251
 252         page_init_poisoning = __page_init_poisoning;
 253
 254         return 1;
 255 }
 256 __setup("vm_debug", setup_vm_debug);
 257
 258 void page_init_poison(struct page *page, size_t size)
 259 {
 260         if (page_init_poisoning)
 261                 memset(page, PAGE_POISON_PATTERN, size);
 262 }
 263 #endif          /* CONFIG_DEBUG_VM */