linux-kernel - Re: [PATCH v2 0/4] hugetlb: Disable huge pmd unshare for uffd-wp

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Date:   Thu, 18 Feb 2021 10:54:41 -0800
From:   Axel Rasmussen <axelrasmussen@...gle.com>
To:     Peter Xu <peterx@...hat.com>
Cc:     Linux MM <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Matthew Wilcox <willy@...radead.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A . Shutemov" <kirill@...temov.name>
Subject: Re: [PATCH v2 0/4] hugetlb: Disable huge pmd unshare for uffd-wp

I reviewed these patches, rebased my minor fault handling series on
top of this series, and then ran some stress tests of minor fault
handling. Other than the one comment I left about !CONFIG_CMA, I
didn't spot any issues. So:

Tested-By: Axel Rasmussen <axelrasmussen@...gle.com>

(Or Reviewed-By: , if that makes more sense.)

On Wed, Feb 17, 2021 at 12:44 PM Peter Xu <peterx@...hat.com> wrote:
>
> v2:
> - patch 4: move hugetlb_unshare_all_pmds() into mm/hugetlb.c, so it can be used
>   even outside userfaultfd.c
>
> This series tries to disable huge pmd unshare of hugetlbfs backed memory for
> uffd-wp.  Although uffd-wp of hugetlbfs is still during rfc stage, the idea of
> this series may be needed for multiple tasks (Axel's uffd minor fault series,
> and Mike's soft dirty series), so I picked it out from the larger series.
>
> References works:
>
> Uffd shmem+hugetlbfs rfc:
> https://lore.kernel.org/lkml/20210115170907.24498-1-peterx@redhat.com/
>
> Uffd minor mode for hugetlbfs:
> https://lore.kernel.org/lkml/20210212215403.3457686-1-axelrasmussen@google.com/
>
> Soft dirty for hugetlbfs:
> https://lore.kernel.org/lkml/20210211000322.159437-1-mike.kravetz@oracle.com/
>
> Please review, thanks.
>
> Peter Xu (4):
>   hugetlb: Pass vma into huge_pte_alloc() and huge_pmd_share()
>   hugetlb/userfaultfd: Forbid huge pmd sharing when uffd enabled
>   mm/hugetlb: Move flush_hugetlb_tlb_range() into hugetlb.h
>   hugetlb/userfaultfd: Unshare all pmds for hugetlbfs when register wp
>
>  arch/arm64/mm/hugetlbpage.c   |  7 ++-
>  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   |  1 +
>  fs/userfaultfd.c              |  4 ++
>  include/linux/hugetlb.h       | 16 +++++-
>  include/linux/userfaultfd_k.h |  9 ++++
>  mm/hugetlb.c                  | 94 +++++++++++++++++++++++++++--------
>  mm/userfaultfd.c              |  2 +-
>  13 files changed, 114 insertions(+), 35 deletions(-)
>
> --
> 2.26.2
>
>