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Revert "mm: use early_pfn_to_nid in page_ext_init"
Qian Cai authored 
[ Upstream commit 2f1ee091 ]

This reverts commit fe53ca54 ("mm: use early_pfn_to_nid in
page_ext_init").

When booting a system with "page_owner=on",

start_kernel
  page_ext_init
    invoke_init_callbacks
      init_section_page_ext
        init_page_owner
          init_early_allocated_pages
            init_zones_in_node
              init_pages_in_zone
                lookup_page_ext
                  page_to_nid

The issue here is that page_to_nid() will not work since some page flags
have no node information until later in page_alloc_init_late() due to
DEFERRED_STRUCT_PAGE_INIT.  Hence, it could trigger an out-of-bounds
access with an invalid nid.

  UBSAN: Undefined behaviour in ./include/linux/mm.h:1104:50
  index 7 is out of range for type 'zone [5]'

Also, kernel will panic since flags were poisoned earlier with,

CONFIG_DEBUG_VM_PGFLAGS=y
CONFIG_NODE_NOT_IN_PAGE_FLAGS=n

start_kernel
  setup_arch
    pagetab...
5a8da52a
Name Last commit Last update
..
Kconfig bpf: introduce BPF_JIT_ALWAYS_ON config
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license
calibrate.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license
do_mounts.c kmemcheck: stop using GFP_NOTRACK and SLAB_NOTRACK
do_mounts.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license
do_mounts_initrd.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license
do_mounts_md.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license
do_mounts_rd.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license
init_task.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license
initramfs.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license
main.c Revert "mm: use early_pfn_to_nid in page_ext_init"
noinitramfs.c init: mark __user address space on string literals
version.c locking/atomic, kref: Add KREF_INIT()