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@xxxxxxxxxx> > --- > 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@xxxxxxxxxx> -- Mike Kravetz
