On 01/04/23 17:52, Peter Xu wrote:
Userfaultfd-wp uses pte markers to mark wr-protected pages for both shmem and hugetlb. Shmem has pre-allocation ready for markers, but hugetlb path was overlooked.
Doing so by calling huge_pte_alloc() if the initial pgtable walk fails to find the huge ptep. It's possible that huge_pte_alloc() can fail with high memory pressure, in that case stop the loop immediately and fail silently. This is not the most ideal solution but it matches with what we do with shmem meanwhile it avoids the splat in dmesg.
Cc: linux-stable stable@vger.kernel.org # 5.19+ Fixes: 60dfaad65aa9 ("mm/hugetlb: allow uffd wr-protect none ptes") Reported-by: James Houghton jthoughton@google.com Signed-off-by: Peter Xu peterx@redhat.com
mm/hugetlb.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
Thanks Peter and James!
Reviewed-by: Mike Kravetz mike.kravetz@oracle.com