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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/init
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Qian Cai 2f1ee0913c Revert "mm: use early_pfn_to_nid in page_ext_init" 
This reverts commit fe53ca5427 ("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
    pagetable_init
      paging_init
        sparse_init
          sparse_init_nid
            memblock_alloc_try_nid_raw

It did not handle it well in init_pages_in_zone() which ends up calling
page_to_nid().

  page:ffffea0004200000 is uninitialized and poisoned
  raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff
  raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff
  page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p))
  page_owner info is not active (free page?)
  kernel BUG at include/linux/mm.h:990!
  RIP: 0010:init_page_owner+0x486/0x520

This means that assumptions behind commit fe53ca5427 ("mm: use
early_pfn_to_nid in page_ext_init") are incomplete.  Therefore, revert
the commit for now.  A proper way to move the page_owner initialization
to sooner is to hook into memmap initialization.

Link: http://lkml.kernel.org/r/20190115202812.75820-1-cai@lca.pw
Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: Michal Hocko <mhocko@kernel.org>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Yang Shi <yang.shi@linaro.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2019-02-12 16:33:18 -08:00
..
Kconfig psi: clarify the Kconfig text for the default-disable option 2019-02-01 15:46:24 -08:00
Makefile Construct init thread stack in the linker script rather than by union 2018-01-09 23:21:02 +00:00
calibrate.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
do_mounts.c vfs: Suppress MS_* flag defs within the kernel unless explicitly enabled 2018-12-20 16:32:56 +00:00
do_mounts.h fs: add do_mknodat() helper and ksys_mknod() wrapper; remove in-kernel calls to syscall 2018-04-02 20:15:56 +02:00
do_mounts_initrd.c Merge branch 'mount.part1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-01-05 13:25:58 -08:00
do_mounts_md.c init/: remove ineffective sparse disabling 2018-08-22 10:52:49 -07:00
do_mounts_rd.c init/: remove ineffective sparse disabling 2018-08-22 10:52:49 -07:00
init_task.c signal: Don't restart fork when signals come in. 2018-08-09 13:07:01 -05:00
initramfs.c initramfs: cleanup incomplete rootfs 2019-01-04 13:13:47 -08:00
main.c Revert "mm: use early_pfn_to_nid in page_ext_init" 2019-02-12 16:33:18 -08:00
noinitramfs.c fs: add do_mknodat() helper and ksys_mknod() wrapper; remove in-kernel calls to syscall 2018-04-02 20:15:56 +02:00
version.c kbuild: Add build salt to the kernel and modules 2018-07-18 01:18:05 +09:00