[RFC PATCH 0/2] Add hstate parameter to huge_pte_offset()

[Punit Agrawal]

On architectures that support hugepages composed of contiguous pte as
well as block entries at the same level in the page table,
huge_pte_offset() is not able to determine the right offset to return
when it encounters a swap entry (which is used to mark poisoned as
well as migrated pages in the page table).

huge_pte_offset() needs to know the size of the hugepage at the
requested address to determine the offset to return - the current
entry or the first entry of a set of contiguous hugepages. This came
up while enabling support for memory failure handling on arm64[0].

Patch 1 adds a hstate parameter to huge_pte_offset() to provide
additional information about the target address. It also updates the
signatures (and usage) of huge_pte_offset() for architectures that
override the generic implementation. This patch has been compile
tested on ia64 and x86.

Patch 2 uses the size determined by the parameter added in Patch 1, to
return the correct page table offset.

The patchset is based on top of v4.11-rc3 and the arm64 huge page
cleanup for break-before-make[1].

Thanks,
Punit


[0] http://marc.info/?l=linux-arm-kernel&m=148772028907925&w=2
[1] https://www.spinics.net/lists/arm-kernel/msg570422.html

Punit Agrawal (2):
  mm/hugetlb.c: add hstate parameter to huge_pte_offset()
  arm64: hugetlbpages: Correctly handle swap entries in
    huge_pte_offset()

 arch/arm64/mm/hugetlbpage.c   | 33 +++++++++++++++++----------------
 arch/ia64/mm/hugetlbpage.c    |  4 ++--
 arch/metag/mm/hugetlbpage.c   |  2 +-
 arch/mips/mm/hugetlbpage.c    |  2 +-
 arch/parisc/mm/hugetlbpage.c  |  2 +-
 arch/powerpc/mm/hugetlbpage.c |  2 +-
 arch/s390/mm/hugetlbpage.c    |  2 +-
 arch/sh/mm/hugetlbpage.c      |  2 +-
 arch/sparc/mm/hugetlbpage.c   |  2 +-
 arch/tile/mm/hugetlbpage.c    |  2 +-
 arch/x86/mm/hugetlbpage.c     |  2 +-
 fs/userfaultfd.c              |  7 +++++--
 include/linux/hugetlb.h       |  2 +-
 mm/hugetlb.c                  | 18 +++++++++---------
 mm/page_vma_mapped.c          |  2 +-
 mm/pagewalk.c                 |  2 +-
 16 files changed, 45 insertions(+), 41 deletions(-)

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2.11.0