[PATCH v3 0/6] userfaultfd: add /dev/userfaultfd for fine grained access control

[Axel Rasmussen]

This series is based on linux-next/akpm-base.

The series is split up like so:
- Patch 1 is a simple fixup which we should take in any case (even by itself).
- Patches 2-4 add the feature, basic support for it to the selftest, and docs.
- Patches 5-6 make the selftest configurable, so you can test one or the other
  instead of always both. If we decide this is overcomplicated, we could just
  drop these two patches and take the rest of the series.

Changelog:

v2->v3:
  - Rebased onto linux-next/akpm-base, in order to be based on top of the
    run_vmtests.sh refactor which was merged previously.
  - Picked up some Reviewed-by's.
  - Fixed ioctl definition (_IO instead of _IOWR), and stopped using
    compat_ptr_ioctl since it is unneeded for ioctls which don't take a pointer.
  - Removed the "handle_kernel_faults" bool, simplifying the code. The result is
    logically equivalent, but simpler.
  - Fixed userfaultfd selftest so it returns KSFT_SKIP appropriately.
  - Reworded documentation per Shuah's feedback on v2.
  - Improved example usage for userfaultfd selftest.

v1->v2:
  - Add documentation update.
  - Test *both* userfaultfd(2) and /dev/userfaultfd via the selftest.

Axel Rasmussen (6):
  selftests: vm: add hugetlb_shared userfaultfd test to run_vmtests.sh
  userfaultfd: add /dev/userfaultfd for fine grained access control
  userfaultfd: selftests: modify selftest to use /dev/userfaultfd
  userfaultfd: update documentation to describe /dev/userfaultfd
  userfaultfd: selftests: make /dev/userfaultfd testing configurable
  selftests: vm: add /dev/userfaultfd test cases to run_vmtests.sh

 Documentation/admin-guide/mm/userfaultfd.rst | 40 ++++++++++-
 Documentation/admin-guide/sysctl/vm.rst      |  3 +
 fs/userfaultfd.c                             | 76 ++++++++++++++++----
 include/uapi/linux/userfaultfd.h             |  4 ++
 tools/testing/selftests/vm/run_vmtests.sh    | 11 ++-
 tools/testing/selftests/vm/userfaultfd.c     | 66 ++++++++++++++---
 6 files changed, 172 insertions(+), 28 deletions(-)

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2.36.1.255.ge46751e96f-goog