lkml.org 
[lkml]   [2023]   [Apr]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH 10/29] selftests/mm: Test UFFDIO_ZEROPAGE only when !hugetlb
    From
    On 01.04.23 03:57, Axel Rasmussen wrote:
    > On Fri, Mar 31, 2023 at 11:37 AM Mike Kravetz <mike.kravetz@oracle.com> wrote:
    >>
    >> On 03/30/23 12:07, Peter Xu wrote:
    >>> Make the check as simple as "test_type == TEST_HUGETLB" because that's the
    >>> only mem that doesn't support ZEROPAGE.
    >>>
    >>> Signed-off-by: Peter Xu <peterx@redhat.com>
    >>> ---
    >>> tools/testing/selftests/mm/userfaultfd.c | 2 +-
    >>> 1 file changed, 1 insertion(+), 1 deletion(-)
    >>>
    >>> diff --git a/tools/testing/selftests/mm/userfaultfd.c b/tools/testing/selftests/mm/userfaultfd.c
    >>> index 795fbc4d84f8..d724f1c78847 100644
    >>> --- a/tools/testing/selftests/mm/userfaultfd.c
    >>> +++ b/tools/testing/selftests/mm/userfaultfd.c
    >>> @@ -1118,7 +1118,7 @@ static int __uffdio_zeropage(int ufd, unsigned long offset, bool retry)
    >>> {
    >>> struct uffdio_zeropage uffdio_zeropage;
    >>> int ret;
    >>> - bool has_zeropage = get_expected_ioctls(0) & (1 << _UFFDIO_ZEROPAGE);
    >>> + bool has_zeropage = !(test_type == TEST_HUGETLB);
    >>
    >> It is true that hugetlb is the only mem type that does not support zeropage.
    >> So, the change is correct.
    >>
    >> However, I actually prefer the explicit check that is there today. It seems
    >> more like a test of the API. And, is more future proof is code changes.
    >>
    >> Just my opinion/thoughts, not a strong objection.
    >
    > I agree. The existing code is more robust to future changes where we
    > might support or stop supporting this ioctl in some cases. It also
    > proves that the ioctl works, any time the API reports that it is
    > supported / ought to work, independent of when the *test* thinks it
    > should be supported.
    >
    > Then again, I think this is unlikely to change in the future, so I
    > also agree with Mike that it's not the biggest deal.

    As there were already discussions on eventually supporting
    UFFDIO_ZEROPAGE that doesn't place the shared zeropage but ... a fresh
    zeropage, it might make sense to keep it as is.

    --
    Thanks,

    David / dhildenb

    \
     
     \ /
      Last update: 2023-04-03 09:57    [W:2.174 / U:0.444 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site