Re: [PATCH v4 1/9] hugetlb: Pass vma into huge_pte_alloc()

[Peter Xu]

On Mon, Feb 01, 2021 at 01:53:14PM -0800, Mike Kravetz wrote:
> On 2/1/21 1:38 PM, Mike Kravetz wrote:
> > On 1/28/21 3:42 PM, Axel Rasmussen wrote:
> >> From: Peter Xu <peterx@xxxxxxxxxx>
> >>
> >> It is a preparation work to be able to behave differently in the per
> >> architecture huge_pte_alloc() according to different VMA attributes.
> >>
> >> Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
> >> [axelrasmussen@xxxxxxxxxx: fixed typo in arch/mips/mm/hugetlbpage.c]
> >> Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
> >> ---
> >>  arch/arm64/mm/hugetlbpage.c   | 2 +-
> >>  arch/ia64/mm/hugetlbpage.c    | 3 ++-
> >>  arch/mips/mm/hugetlbpage.c    | 4 ++--
> >>  arch/parisc/mm/hugetlbpage.c  | 2 +-
> >>  arch/powerpc/mm/hugetlbpage.c | 3 ++-
> >>  arch/s390/mm/hugetlbpage.c    | 2 +-
> >>  arch/sh/mm/hugetlbpage.c      | 2 +-
> >>  arch/sparc/mm/hugetlbpage.c   | 2 +-
> >>  include/linux/hugetlb.h       | 2 +-
> >>  mm/hugetlb.c                  | 6 +++---
> >>  mm/userfaultfd.c              | 2 +-
> >>  11 files changed, 16 insertions(+), 14 deletions(-)
> > 
> > Sorry for the delay in reviewing.
> > 
> > huge_pmd_share() will do a find_vma() to get the vma.  So, it would be
> > 'possible' to not add an extra argument to huge_pmd_alloc() and simply
> > do the uffd_disable_huge_pmd_share() check inside vma_shareable.  This
> > would reduce the amount of modified code, but would not be as efficient.
> > I prefer passing the vma argument as is done here.
> > 
> > Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> 
> 
> Another thought.
> 
> We should pass the vma to huge_pmd_share to avoid the find_vma.

Agreed.  Seems not relevant to this series, but should be a very nice add-on
after this patch can land.  Thanks,

-- 
Peter Xu