text: // 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"
  
  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)
  {
  	bool page_poisoned = PagePoisoned(page);
  	int mapcount;
  
  	/*
  	 * 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_emerg("page:%px is uninitialized and poisoned", page);
  		goto hex_only;
  	}
  
  	/*
  	 * 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(page) ? 0 : page_mapcount(page);
  
  	pr_emerg("page:%px count:%d mapcount:%d mapping:%px index:%#lx",
  		  page, page_ref_count(page), mapcount,
  		  page->mapping, page_to_pgoff(page));
  	if (PageCompound(page))
  		pr_cont(" compound_mapcount: %d", compound_mapcount(page));
  	pr_cont("\n");
  	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
  
  	pr_emerg("flags: %#lx(%pGp)\n", page->flags, &page->flags);
  
  hex_only:
  	print_hex_dump(KERN_ALERT, "raw: ", DUMP_PREFIX_NONE, 32,
  			sizeof(unsigned long), page,
  			sizeof(struct page), false);
  
  	if (reason)
  		pr_alert("page dumped because: %s\n", reason);
  
  #ifdef CONFIG_MEMCG
  	if (!page_poisoned && page->mem_cgroup)
  		pr_alert("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 %lx 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
  		"mmu_notifier_mm %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,
  		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->mmu_notifier_mm,
  #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 */
  