[PATCH v4 0/8] Support for transparent PUD pages for DAX files

[Matthew Wilcox]

We have customer demand to use 1GB pages to map DAX files.  Unlike the 2MB
page support, the Linux MM does not currently support PUD pages, so I have
attempted to add support for the necessary pieces for DAX huge PUD pages.

Filesystems still need work to allocate 1GB pages.  With ext4, I can
only get 16MB of contiguous space, although it is aligned.  With XFS,
I can get 80MB less than 1GB, and it's not aligned.  The XFS problem
may be due to the small amount of RAM in my test machine.

This patch set is against something approximately current -mm.  I'd like
to thank Dave Chinner & Kirill Shutemov for their reviews of v1.
The conversion of pmd_fault & pud_fault to huge_fault is thanks to
Dave's poking, and Kirill spotted a couple of problems in the MM code.
Version 2 of the patch set is about 200 lines smaller (1016 insertions,
23 deletions in v1).

I've done some light testing using a program to mmap a block device
with DAX enabled, calling mincore() and examining /proc/smaps and
/proc/pagemap.

v4: Updated to current mmotm
    Converted pud_trans_huge_lock to the same calling conventions as
    pmd_trans_huge_lock.
    Fill in vm_fault ->gfp_flags and ->pgoff, at Jan Kara's suggestion
    Replace use of page table lock with pud_lock in __pud_alloc (cosmetic)
    Fix compilation problems with various config settings
    Convert dax_pmd_fault and dax_pud_fault to take a vm_fault instead of
    individual pieces
    Add copy_huge_pud() and follow_devmap_pud() so fork() should now work
    Fix typo of PMD for PUD
v3: Rebased against current mmtom
v2: Reduced churn in filesystems by switching to ->huge_fault interface
    Addressed concerns from Kirill

Matthew Wilcox (8):
  mm: Convert an open-coded VM_BUG_ON_VMA
  mm,fs,dax: Change ->pmd_fault to ->huge_fault
  mm: Add support for PUD-sized transparent hugepages
  mincore: Add support for PUDs
  procfs: Add support for PUDs to smaps, clear_refs and pagemap
  x86: Add support for PUD-sized transparent hugepages
  dax: Support for transparent PUD pages
  ext4: Support for PUD-sized transparent huge pages

 Documentation/filesystems/dax.txt     |  12 +-
 arch/Kconfig                          |   3 +
 arch/x86/Kconfig                      |   1 +
 arch/x86/include/asm/paravirt.h       |  11 ++
 arch/x86/include/asm/paravirt_types.h |   2 +
 arch/x86/include/asm/pgtable-2level.h |  19 +++
 arch/x86/include/asm/pgtable-3level.h |  31 ++++
 arch/x86/include/asm/pgtable.h        | 134 +++++++++++++++
 arch/x86/include/asm/pgtable_64.h     |  13 ++
 arch/x86/kernel/paravirt.c            |   1 +
 arch/x86/mm/pgtable.c                 |  31 ++++
 fs/block_dev.c                        |  10 +-
 fs/dax.c                              | 295 +++++++++++++++++++++++++---------
 fs/ext2/file.c                        |  27 +---
 fs/ext4/file.c                        |  60 +++----
 fs/proc/task_mmu.c                    | 109 +++++++++++++
 fs/xfs/xfs_file.c                     |  25 ++-
 fs/xfs/xfs_trace.h                    |   2 +-
 include/asm-generic/pgtable.h         |  74 ++++++++-
 include/asm-generic/tlb.h             |  14 ++
 include/linux/dax.h                   |  17 --
 include/linux/huge_mm.h               |  78 ++++++++-
 include/linux/mm.h                    |  48 +++++-
 include/linux/mmu_notifier.h          |  14 ++
 include/linux/pfn_t.h                 |   8 +
 mm/gup.c                              |   7 +
 mm/huge_memory.c                      | 246 ++++++++++++++++++++++++++++
 mm/memory.c                           | 135 ++++++++++++++--
 mm/mincore.c                          |  13 ++
 mm/pagewalk.c                         |  19 ++-
 mm/pgtable-generic.c                  |  14 ++
 31 files changed, 1261 insertions(+), 212 deletions(-)

-- 
2.7.0.rc3