[V2,0/2] Fixes for contiguous hugetlb

Message

Steve Capper Sept. 21, 2018, 3:34 p.m. UTC

This patch series addresses a couple of issues found with contiguous hugetlb.

1) It is possible for old hugetlb's to be created by remove_migration_pte, the
   first patch adjusts the code to capture any young ptes that could have been
   created by hardware dirty bit management.

2) huge_ptep_set_access_flags has been changed in the second patch to prevent it
   from unnecessarily invalidating contiguous hugetlb mappings (which also stops
   it from potentially evoking back-to-back page faults).

These patches have not yet been tested on hardware. 

Steve Capper (2):
  arm64: hugetlb: Fix handling of young ptes
  arm64: hugetlb: Avoid unnecessary clearing in
    huge_ptep_set_access_flags

 arch/arm64/mm/hugetlbpage.c | 50 ++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 43 insertions(+), 7 deletions(-)

Comments

Will Deacon Sept. 24, 2018, 4:25 p.m. UTC | #1

On Fri, Sep 21, 2018 at 04:34:03PM +0100, Steve Capper wrote:
> This patch series addresses a couple of issues found with contiguous hugetlb.
> 
> 1) It is possible for old hugetlb's to be created by remove_migration_pte, the
>    first patch adjusts the code to capture any young ptes that could have been
>    created by hardware dirty bit management.
> 
> 2) huge_ptep_set_access_flags has been changed in the second patch to prevent it
>    from unnecessarily invalidating contiguous hugetlb mappings (which also stops
>    it from potentially evoking back-to-back page faults).

Thanks Steve, these look good to me. I'll pick them up as fixes.

Will