diff options
Diffstat (limited to 'mm/debug.c')
| -rw-r--r-- | mm/debug.c | 324 |
1 files changed, 324 insertions, 0 deletions
diff --git a/mm/debug.c b/mm/debug.c new file mode 100644 index 000000000..ccca576b2 --- /dev/null +++ b/mm/debug.c @@ -0,0 +1,324 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * mm/debug.c + * + * mm/ specific debug routines. + * + */ + +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/trace_events.h> +#include <linux/memcontrol.h> +#include <trace/events/mmflags.h> +#include <linux/migrate.h> +#include <linux/page_owner.h> +#include <linux/ctype.h> + +#include "internal.h" + +const char *migrate_reason_names[MR_TYPES] = { + "compaction", + "memory_failure", + "memory_hotplug", + "syscall_or_cpuset", + "mempolicy_mbind", + "numa_misplaced", + "cma", +}; + +const struct trace_print_flags pageflag_names[] = { + __def_pageflag_names, + {0, NULL} +}; + +const struct trace_print_flags gfpflag_names[] = { + __def_gfpflag_names, + {0, NULL} +}; + +const struct trace_print_flags vmaflag_names[] = { + __def_vmaflag_names, + {0, NULL} +}; + +void __dump_page(struct page *page, const char *reason) +{ + struct page *head = compound_head(page); + struct address_space *mapping; + bool page_poisoned = PagePoisoned(page); + bool compound = PageCompound(page); + /* + * Accessing the pageblock without the zone lock. It could change to + * "isolate" again in the meantime, but since we are just dumping the + * state for debugging, it should be fine to accept a bit of + * inaccuracy here due to racing. + */ + bool page_cma = is_migrate_cma_page(page); + int mapcount; + char *type = ""; + + /* + * If struct page is poisoned don't access Page*() functions as that + * leads to recursive loop. Page*() check for poisoned pages, and calls + * dump_page() when detected. + */ + if (page_poisoned) { + pr_warn("page:%px is uninitialized and poisoned", page); + goto hex_only; + } + + if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) { + /* + * Corrupt page, so we cannot call page_mapping. Instead, do a + * safe subset of the steps that page_mapping() does. Caution: + * this will be misleading for tail pages, PageSwapCache pages, + * and potentially other situations. (See the page_mapping() + * implementation for what's missing here.) + */ + unsigned long tmp = (unsigned long)page->mapping; + + if (tmp & PAGE_MAPPING_ANON) + mapping = NULL; + else + mapping = (void *)(tmp & ~PAGE_MAPPING_FLAGS); + head = page; + compound = false; + } else { + mapping = page_mapping(page); + } + + /* + * Avoid VM_BUG_ON() in page_mapcount(). + * page->_mapcount space in struct page is used by sl[aou]b pages to + * encode own info. + */ + mapcount = PageSlab(head) ? 0 : page_mapcount(page); + + pr_warn("page:%p refcount:%d mapcount:%d mapping:%p index:%#lx pfn:%#lx\n", + page, page_ref_count(head), mapcount, mapping, + page_to_pgoff(page), page_to_pfn(page)); + if (compound) { + if (hpage_pincount_available(page)) { + pr_warn("head:%p order:%u compound_mapcount:%d compound_pincount:%d\n", + head, compound_order(head), + head_compound_mapcount(head), + head_compound_pincount(head)); + } else { + pr_warn("head:%p order:%u compound_mapcount:%d\n", + head, compound_order(head), + head_compound_mapcount(head)); + } + } + if (PageKsm(page)) + type = "ksm "; + else if (PageAnon(page)) + type = "anon "; + else if (mapping) { + struct inode *host; + const struct address_space_operations *a_ops; + struct hlist_node *dentry_first; + struct dentry *dentry_ptr; + struct dentry dentry; + unsigned long ino; + + /* + * mapping can be invalid pointer and we don't want to crash + * accessing it, so probe everything depending on it carefully + */ + if (get_kernel_nofault(host, &mapping->host) || + get_kernel_nofault(a_ops, &mapping->a_ops)) { + pr_warn("failed to read mapping contents, not a valid kernel address?\n"); + goto out_mapping; + } + + if (!host) { + pr_warn("aops:%ps\n", a_ops); + goto out_mapping; + } + + if (get_kernel_nofault(dentry_first, &host->i_dentry.first) || + get_kernel_nofault(ino, &host->i_ino)) { + pr_warn("aops:%ps with invalid host inode %px\n", + a_ops, host); + goto out_mapping; + } + + if (!dentry_first) { + pr_warn("aops:%ps ino:%lx\n", a_ops, ino); + goto out_mapping; + } + + dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias); + if (get_kernel_nofault(dentry, dentry_ptr)) { + pr_warn("aops:%ps ino:%lx with invalid dentry %px\n", + a_ops, ino, dentry_ptr); + } else { + /* + * if dentry is corrupted, the %pd handler may still + * crash, but it's unlikely that we reach here with a + * corrupted struct page + */ + pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n", + a_ops, ino, &dentry); + } + } +out_mapping: + BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1); + + pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags, &head->flags, + page_cma ? " CMA" : ""); + +hex_only: + print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32, + sizeof(unsigned long), page, + sizeof(struct page), false); + if (head != page) + print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32, + sizeof(unsigned long), head, + sizeof(struct page), false); + + if (reason) + pr_warn("page dumped because: %s\n", reason); + +#ifdef CONFIG_MEMCG + if (!page_poisoned && page->mem_cgroup) + pr_warn("page->mem_cgroup:%px\n", page->mem_cgroup); +#endif +} + +void dump_page(struct page *page, const char *reason) +{ + __dump_page(page, reason); + dump_page_owner(page); +} +EXPORT_SYMBOL(dump_page); + +#ifdef CONFIG_DEBUG_VM + +void dump_vma(const struct vm_area_struct *vma) +{ + pr_emerg("vma %px start %px end %px\n" + "next %px prev %px mm %px\n" + "prot %lx anon_vma %px vm_ops %px\n" + "pgoff %lx file %px private_data %px\n" + "flags: %#lx(%pGv)\n", + vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next, + vma->vm_prev, vma->vm_mm, + (unsigned long)pgprot_val(vma->vm_page_prot), + vma->anon_vma, vma->vm_ops, vma->vm_pgoff, + vma->vm_file, vma->vm_private_data, + vma->vm_flags, &vma->vm_flags); +} +EXPORT_SYMBOL(dump_vma); + +void dump_mm(const struct mm_struct *mm) +{ + pr_emerg("mm %px mmap %px seqnum %llu task_size %lu\n" +#ifdef CONFIG_MMU + "get_unmapped_area %px\n" +#endif + "mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n" + "pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n" + "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n" + "pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n" + "start_code %lx end_code %lx start_data %lx end_data %lx\n" + "start_brk %lx brk %lx start_stack %lx\n" + "arg_start %lx arg_end %lx env_start %lx env_end %lx\n" + "binfmt %px flags %lx core_state %px\n" +#ifdef CONFIG_AIO + "ioctx_table %px\n" +#endif +#ifdef CONFIG_MEMCG + "owner %px " +#endif + "exe_file %px\n" +#ifdef CONFIG_MMU_NOTIFIER + "notifier_subscriptions %px\n" +#endif +#ifdef CONFIG_NUMA_BALANCING + "numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n" +#endif + "tlb_flush_pending %d\n" + "def_flags: %#lx(%pGv)\n", + + mm, mm->mmap, (long long) mm->vmacache_seqnum, mm->task_size, +#ifdef CONFIG_MMU + mm->get_unmapped_area, +#endif + mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end, + mm->pgd, atomic_read(&mm->mm_users), + atomic_read(&mm->mm_count), + mm_pgtables_bytes(mm), + mm->map_count, + mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm, + (u64)atomic64_read(&mm->pinned_vm), + mm->data_vm, mm->exec_vm, mm->stack_vm, + mm->start_code, mm->end_code, mm->start_data, mm->end_data, + mm->start_brk, mm->brk, mm->start_stack, + mm->arg_start, mm->arg_end, mm->env_start, mm->env_end, + mm->binfmt, mm->flags, mm->core_state, +#ifdef CONFIG_AIO + mm->ioctx_table, +#endif +#ifdef CONFIG_MEMCG + mm->owner, +#endif + mm->exe_file, +#ifdef CONFIG_MMU_NOTIFIER + mm->notifier_subscriptions, +#endif +#ifdef CONFIG_NUMA_BALANCING + mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq, +#endif + atomic_read(&mm->tlb_flush_pending), + mm->def_flags, &mm->def_flags + ); +} + +static bool page_init_poisoning __read_mostly = true; + +static int __init setup_vm_debug(char *str) +{ + bool __page_init_poisoning = true; + + /* + * Calling vm_debug with no arguments is equivalent to requesting + * to enable all debugging options we can control. + */ + if (*str++ != '=' || !*str) + goto out; + + __page_init_poisoning = false; + if (*str == '-') + goto out; + + while (*str) { + switch (tolower(*str)) { + case'p': + __page_init_poisoning = true; + break; + default: + pr_err("vm_debug option '%c' unknown. skipped\n", + *str); + } + + str++; + } +out: + if (page_init_poisoning && !__page_init_poisoning) + pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n"); + + page_init_poisoning = __page_init_poisoning; + + return 1; +} +__setup("vm_debug", setup_vm_debug); + +void page_init_poison(struct page *page, size_t size) +{ + if (page_init_poisoning) + memset(page, PAGE_POISON_PATTERN, size); +} +EXPORT_SYMBOL_GPL(page_init_poison); +#endif /* CONFIG_DEBUG_VM */ |