On Fri, Jun 21, 2024 at 05:27:43PM -0400, Peter Xu wrote:
> On Fri, Jun 21, 2024 at 02:12:24PM -0400, Audra Mitchell wrote:
> > If CONFIG_PTE_MARKER_UFFD_WP is disabled, then testing with test_uffdio_up
>
> Here you're talking about pte markers, then..
>
> > enables calling uffdio_regsiter with the flag UFFDIO_REGISTER_MODE_WP. The
> > kernel ensures in vma_can_userfault() that if CONFIG_PTE_MARKER_UFFD_WP
> > is disabled, only allow the VM_UFFD_WP on anonymous vmas.
> >
> > Signed-off-by: Audra Mitchell <audra@xxxxxxxxxx>
> > ---
> > tools/testing/selftests/mm/uffd-stress.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c
> > index b9b6d858eab8..2601c9dfadd6 100644
> > --- a/tools/testing/selftests/mm/uffd-stress.c
> > +++ b/tools/testing/selftests/mm/uffd-stress.c
> > @@ -419,6 +419,9 @@ static void parse_test_type_arg(const char *raw_type)
> > test_uffdio_wp = test_uffdio_wp &&
> > (features & UFFD_FEATURE_PAGEFAULT_FLAG_WP);
> >
> > + if (test_type != TEST_ANON && !(features & UFFD_FEATURE_WP_UNPOPULATED))
> > + test_uffdio_wp = false;
>
> ... here you're checking against wp_unpopulated. I'm slightly confused.
>
> Are you running this test over shmem/hugetlb when the WP feature isn't
> supported?
>
> I'm wondering whether you're looking for UFFD_FEATURE_WP_HUGETLBFS_SHMEM
> instead.
I can confirm, its all really confusing... So in userfaultfd_api, we disable
three features if CONFIG_PTE_MARKER_UFFD_WP is not enabled- including
UFFD_FEATURE_WP_UNPOPULATED:
#ifndef CONFIG_PTE_MARKER_UFFD_WP
uffdio_api.features &= ~UFFD_FEATURE_WP_HUGETLBFS_SHMEM;
uffdio_api.features &= ~UFFD_FEATURE_WP_UNPOPULATED;
uffdio_api.features &= ~UFFD_FEATURE_WP_ASYNC;
#endif
If you run the userfaultfd selftests with the run_vmtests script we get
several failures stemming from trying to call uffdio_regsiter with the flag
UFFDIO_REGISTER_MODE_WP. However, the kernel ensures in vma_can_userfault()
that if CONFIG_PTE_MARKER_UFFD_WP is disabled, only allow the VM_UFFD_WP -
which is set when you pass the UFFDIO_REGISTER_MODE_WP flag - on
anonymous vmas.
In parse_test_type_arg() I added the features check against
UFFD_FEATURE_WP_UNPOPULATED as it seemed the most well know feature/flag. I'm
more than happy to take any suggestions and adapt them if you have any!
Thanks in advance and happy Monday!
-- Audra
> Thanks,
>
> > +
> > close(uffd);
> > uffd = -1;
> > }
> > --
> > 2.44.0
> >
>
> --
> Peter Xu
>
