Messages in this thread | | | Subject | Re: [PATCH v3 4/4] hugetlb/userfaultfd: Unshare all pmds for hugetlbfs when register wp | From | Mike Kravetz <> | Date | Thu, 18 Feb 2021 14:18:44 -0800 |
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On 2/18/21 1:55 PM, Peter Xu wrote: > Huge pmd sharing for hugetlbfs is racy with userfaultfd-wp because > userfaultfd-wp is always based on pgtable entries, so they cannot be shared. > > Walk the hugetlb range and unshare all such mappings if there is, right before > UFFDIO_REGISTER will succeed and return to userspace. > > This will pair with want_pmd_share() in hugetlb code so that huge pmd sharing > is completely disabled for userfaultfd-wp registered range. > > Signed-off-by: Peter Xu <peterx@redhat.com> > --- > fs/userfaultfd.c | 4 ++++ > include/linux/hugetlb.h | 3 +++ > mm/hugetlb.c | 51 +++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 58 insertions(+)
Thanks, Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> -- Mike Kravetz
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