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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-24 15:01:13 +07:00
5ae2efb1de
While debugging something, I added a dump_page() into do_swap_page(),
and I got the splat from below. The issue happens when dereferencing
mapping->host in __dump_page():
...
else if (mapping) {
pr_warn("%ps ", mapping->a_ops);
if (mapping->host->i_dentry.first) {
struct dentry *dentry;
dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
pr_warn("name:\"%pd\" ", dentry);
}
}
...
Swap address space does not contain an inode information, and so
mapping->host equals NULL.
Although the dump_page() call was added artificially into
do_swap_page(), I am not sure if we can hit this from any other path, so
it looks worth fixing it. We can easily do that by checking
mapping->host first.
Link: http://lkml.kernel.org/r/20190318072931.29094-1-osalvador@suse.de
Fixes: 1c6fb1d89e
("mm: print more information about mapping in __dump_page")
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
241 lines
5.9 KiB
C
241 lines
5.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* mm/debug.c
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*
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* mm/ specific debug routines.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/trace_events.h>
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#include <linux/memcontrol.h>
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#include <trace/events/mmflags.h>
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#include <linux/migrate.h>
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#include <linux/page_owner.h>
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#include <linux/ctype.h>
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#include "internal.h"
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const char *migrate_reason_names[MR_TYPES] = {
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"compaction",
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"memory_failure",
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"memory_hotplug",
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"syscall_or_cpuset",
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"mempolicy_mbind",
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"numa_misplaced",
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"cma",
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};
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const struct trace_print_flags pageflag_names[] = {
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__def_pageflag_names,
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{0, NULL}
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};
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const struct trace_print_flags gfpflag_names[] = {
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__def_gfpflag_names,
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{0, NULL}
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};
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const struct trace_print_flags vmaflag_names[] = {
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__def_vmaflag_names,
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{0, NULL}
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};
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void __dump_page(struct page *page, const char *reason)
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{
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struct address_space *mapping;
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bool page_poisoned = PagePoisoned(page);
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int mapcount;
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/*
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* If struct page is poisoned don't access Page*() functions as that
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* leads to recursive loop. Page*() check for poisoned pages, and calls
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* dump_page() when detected.
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*/
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if (page_poisoned) {
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pr_warn("page:%px is uninitialized and poisoned", page);
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goto hex_only;
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}
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mapping = page_mapping(page);
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/*
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* Avoid VM_BUG_ON() in page_mapcount().
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* page->_mapcount space in struct page is used by sl[aou]b pages to
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* encode own info.
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*/
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mapcount = PageSlab(page) ? 0 : page_mapcount(page);
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pr_warn("page:%px count:%d mapcount:%d mapping:%px index:%#lx",
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page, page_ref_count(page), mapcount,
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page->mapping, page_to_pgoff(page));
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if (PageCompound(page))
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pr_cont(" compound_mapcount: %d", compound_mapcount(page));
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pr_cont("\n");
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if (PageAnon(page))
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pr_warn("anon ");
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else if (PageKsm(page))
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pr_warn("ksm ");
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else if (mapping) {
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pr_warn("%ps ", mapping->a_ops);
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if (mapping->host && mapping->host->i_dentry.first) {
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struct dentry *dentry;
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dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
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pr_warn("name:\"%pd\" ", dentry);
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}
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}
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BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
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pr_warn("flags: %#lx(%pGp)\n", page->flags, &page->flags);
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hex_only:
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print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
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sizeof(unsigned long), page,
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sizeof(struct page), false);
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if (reason)
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pr_warn("page dumped because: %s\n", reason);
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#ifdef CONFIG_MEMCG
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if (!page_poisoned && page->mem_cgroup)
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pr_warn("page->mem_cgroup:%px\n", page->mem_cgroup);
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#endif
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}
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void dump_page(struct page *page, const char *reason)
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{
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__dump_page(page, reason);
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dump_page_owner(page);
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}
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EXPORT_SYMBOL(dump_page);
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#ifdef CONFIG_DEBUG_VM
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void dump_vma(const struct vm_area_struct *vma)
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{
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pr_emerg("vma %px start %px end %px\n"
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"next %px prev %px mm %px\n"
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"prot %lx anon_vma %px vm_ops %px\n"
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"pgoff %lx file %px private_data %px\n"
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"flags: %#lx(%pGv)\n",
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vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
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vma->vm_prev, vma->vm_mm,
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(unsigned long)pgprot_val(vma->vm_page_prot),
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vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
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vma->vm_file, vma->vm_private_data,
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vma->vm_flags, &vma->vm_flags);
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}
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EXPORT_SYMBOL(dump_vma);
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void dump_mm(const struct mm_struct *mm)
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{
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pr_emerg("mm %px mmap %px seqnum %llu task_size %lu\n"
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#ifdef CONFIG_MMU
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"get_unmapped_area %px\n"
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#endif
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"mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
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"pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
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"hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
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"pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
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"start_code %lx end_code %lx start_data %lx end_data %lx\n"
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"start_brk %lx brk %lx start_stack %lx\n"
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"arg_start %lx arg_end %lx env_start %lx env_end %lx\n"
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"binfmt %px flags %lx core_state %px\n"
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#ifdef CONFIG_AIO
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"ioctx_table %px\n"
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#endif
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#ifdef CONFIG_MEMCG
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"owner %px "
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#endif
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"exe_file %px\n"
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#ifdef CONFIG_MMU_NOTIFIER
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"mmu_notifier_mm %px\n"
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#endif
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#ifdef CONFIG_NUMA_BALANCING
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"numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n"
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#endif
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"tlb_flush_pending %d\n"
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"def_flags: %#lx(%pGv)\n",
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mm, mm->mmap, (long long) mm->vmacache_seqnum, mm->task_size,
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#ifdef CONFIG_MMU
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mm->get_unmapped_area,
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#endif
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mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
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mm->pgd, atomic_read(&mm->mm_users),
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atomic_read(&mm->mm_count),
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mm_pgtables_bytes(mm),
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mm->map_count,
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mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm,
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(u64)atomic64_read(&mm->pinned_vm),
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mm->data_vm, mm->exec_vm, mm->stack_vm,
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mm->start_code, mm->end_code, mm->start_data, mm->end_data,
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mm->start_brk, mm->brk, mm->start_stack,
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mm->arg_start, mm->arg_end, mm->env_start, mm->env_end,
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mm->binfmt, mm->flags, mm->core_state,
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#ifdef CONFIG_AIO
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mm->ioctx_table,
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#endif
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#ifdef CONFIG_MEMCG
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mm->owner,
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#endif
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mm->exe_file,
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#ifdef CONFIG_MMU_NOTIFIER
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mm->mmu_notifier_mm,
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#endif
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#ifdef CONFIG_NUMA_BALANCING
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mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq,
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#endif
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atomic_read(&mm->tlb_flush_pending),
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mm->def_flags, &mm->def_flags
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);
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}
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static bool page_init_poisoning __read_mostly = true;
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static int __init setup_vm_debug(char *str)
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{
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bool __page_init_poisoning = true;
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/*
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* Calling vm_debug with no arguments is equivalent to requesting
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* to enable all debugging options we can control.
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*/
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if (*str++ != '=' || !*str)
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goto out;
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__page_init_poisoning = false;
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if (*str == '-')
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goto out;
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while (*str) {
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switch (tolower(*str)) {
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case'p':
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__page_init_poisoning = true;
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break;
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default:
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pr_err("vm_debug option '%c' unknown. skipped\n",
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*str);
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}
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str++;
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}
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out:
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if (page_init_poisoning && !__page_init_poisoning)
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pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n");
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page_init_poisoning = __page_init_poisoning;
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return 1;
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}
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__setup("vm_debug", setup_vm_debug);
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void page_init_poison(struct page *page, size_t size)
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{
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if (page_init_poisoning)
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memset(page, PAGE_POISON_PATTERN, size);
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}
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EXPORT_SYMBOL_GPL(page_init_poison);
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#endif /* CONFIG_DEBUG_VM */
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