[PATCH v7 0/6] Fix some bugs related to ramp and dax

[Muchun Song <songmuchun@bytedance.com>]

This series is based on next-20220225.

Patch 1-2 fix a cache flush bug, because subsequent patches depend on
those on those changes, there are placed in this series.  Patch 3-4
are preparation for fixing a dax bug in patch 5.  Patch 6 is code cleanup
since the previous patch remove the usage of follow_invalidate_pte().

v7:
- Remove redurant "*" above vma_address() reported by Christoph.
- Fix oops (reported by Qian) on arm64 by using "pmd_present() && pmd_devmap()"
  to workaround the bug in pmd_leaf() on arm64, which is fixed in another
  patch [1].

[1] https://lore.kernel.org/all/20220403024928.4125-1-songmuchun@bytedance.com/

v6:
- Collect Reviewed-by from Christoph Hellwig.
- Fold dax_entry_mkclean() into dax_writeback_one().

v5:
- Collect Reviewed-by from Dan Williams.
- Fix panic reported by kernel test robot <oliver.sang@intel.com>.
- Remove pmdpp parameter from follow_invalidate_pte() and fold it into follow_pte().

v4:
- Fix compilation error on riscv.

v3:
- Based on next-20220225.

v2:
- Avoid the overly long line in lots of places suggested by Christoph.
- Fix a compiler warning reported by kernel test robot since pmd_pfn()
  is not defined when !CONFIG_TRANSPARENT_HUGEPAGE on powerpc architecture.
- Split a new patch 4 for preparation of fixing the dax bug.

Muchun Song (6):
  mm: rmap: fix cache flush on THP pages
  dax: fix cache flush on PMD-mapped pages
  mm: rmap: introduce pfn_mkclean_range() to cleans PTEs
  mm: pvmw: add support for walking devmap pages
  dax: fix missing writeprotect the pte entry
  mm: simplify follow_invalidate_pte()

 fs/dax.c             | 98 +++++++---------------------------------------------
 include/linux/mm.h   |  3 --
 include/linux/rmap.h |  3 ++
 mm/internal.h        | 26 +++++++++-----
 mm/memory.c          | 81 ++++++++++++-------------------------------
 mm/page_vma_mapped.c | 17 ++++-----
 mm/rmap.c            | 68 +++++++++++++++++++++++++++++-------
 7 files changed, 120 insertions(+), 176 deletions(-)

-- 
2.11.0