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Linux/mm/debug.c

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  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 */
318 

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