[v2,0/4] hugetlb: speed up linear address scanning

Message

Mike Kravetz June 21, 2022, 11:56 p.m. UTC

At unmap, fork and remap time hugetlb address ranges are linearly
scanned.  We can optimize these scans if the ranges are sparsely
populated.

Also, enable page table "Lazy copy" for hugetlb at fork.

NOTE: Architectures not defining CONFIG_ARCH_WANT_GENERAL_HUGETLB
need to add an arch specific version hugetlb_mask_last_page() to
take advantage of sparse address scanning improvements.  Baolin Wang
added the routine for arm64.  Other architectures which could be
optimized are: ia64, mips, parisc, powerpc, s390, sh and sparc.

v1->v2  Change hugetlb_mask_last_page default code to 0 instead of ~0.  Peter
        Fix build issues on i386, including going back to if-else-if
	instead of switch in hugetlb_mask_last_page. kernel test robot
        Update commit message. Rolf Eike Beer
        Changes were relatively minor, so I left the Reviewed-by and
        ACKed-by tags.

Baolin Wang (1):
  arm64/hugetlb: Implement arm64 specific hugetlb_mask_last_page

Mike Kravetz (3):
  hugetlb: skip to end of PT page mapping when pte not present
  hugetlb: do not update address in huge_pmd_unshare
  hugetlb: Lazy page table copies in fork()

 arch/arm64/mm/hugetlbpage.c |  20 +++++++
 include/linux/hugetlb.h     |   5 +-
 mm/hugetlb.c                | 102 +++++++++++++++++++++++++-----------
 mm/memory.c                 |   2 +-
 mm/rmap.c                   |   4 +-
 5 files changed, 96 insertions(+), 37 deletions(-)