Re: [RFC PATCH v3 2/2] selftests: restrictedmem: Check hugepage-ness of shmem file backing restrictedmem fd

[Ackerley Tng]

David Hildenbrand <david@xxxxxxxxxx> writes:

> On 01.04.23 01:50, Ackerley Tng wrote:
> > For memfd_restricted() calls without a userspace mount, the backing
> > file should be the shmem mount in the kernel, and the size of backing
> > pages should be as defined by system-wide shmem configuration.

> > If a userspace mount is provided, the size of backing pages should be
> > as defined in the mount.

> > Also includes negative tests for invalid inputs, including fds
> > representing read-only superblocks/mounts.


> When you talk about "hugepage" in this patch, do you mean THP or
> hugetlb? I suspect thp, so it might be better to spell that out. IIRC,
> there are plans to support actual huge pages in the future, at which
> point "hugepage" terminology could be misleading.


Thanks for pointing this out! I've replaced references to hugepage with
thp, please see RFC v4 at
https://lore.kernel.org/lkml/cover.1681176340.git.ackerleytng@xxxxxxxxxx/T/

> > Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
> > ---
> >    tools/testing/selftests/Makefile              |   1 +
> >    .../selftests/restrictedmem/.gitignore        |   3 +
> >    .../testing/selftests/restrictedmem/Makefile  |  15 +
> >    .../testing/selftests/restrictedmem/common.c  |   9 +
> >    .../testing/selftests/restrictedmem/common.h  |   8 +
> >    .../restrictedmem_hugepage_test.c             | 486 ++++++++++++++++++
> >    6 files changed, 522 insertions(+)
> >    create mode 100644 tools/testing/selftests/restrictedmem/.gitignore
> >    create mode 100644 tools/testing/selftests/restrictedmem/Makefile
> >    create mode 100644 tools/testing/selftests/restrictedmem/common.c
> >    create mode 100644 tools/testing/selftests/restrictedmem/common.h
> >    create mode 100644  
> > tools/testing/selftests/restrictedmem/restrictedmem_hugepage_test.c

> > ...