[PATCH 0/7] userfaultfd: add support for shared memory

[Mike Rapoport]

These patches enable userfaultfd support for shared memory mappings. The
VMAs backed with shmem/tmpfs can be registered with userfaultfd which
allows management of page faults in these areas by userland.

This patch set adds implementation of shmem_mcopy_atomic_pte for proper
handling of UFFDIO_COPY command. A callback to handle_userfault is added
to shmem page fault handling path. The userfaultfd register/unregister
methods are extended to allow shmem VMAs.

The UFFDIO_ZEROPAGE and UFFDIO_REGISTER_MODE_WP are not implemented which
is reflected by userfaultfd API handshake methods.

The patches are based on current Andrea's tree:
https://git.kernel.org/pub/scm/linux/kernel/git/andrea/aa.git

Mike Rapoport (7):
  userfaultfd: introduce vma_can_userfault
  userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support
  userfaultfd: shmem: introduce vma_is_shmem
  userfaultfd: shmem: use shmem_mcopy_atomic_pte for shared memory
  userfaultfd: shmem: add userfaultfd hook for shared memory faults
  userfaultfd: shmem: allow registration of shared memory ranges
  userfaultfd: shmem: add userfaultfd_shmem test

 fs/userfaultfd.c                         |  32 ++++---
 include/linux/mm.h                       |  10 +++
 include/linux/shmem_fs.h                 |  11 +++
 include/uapi/linux/userfaultfd.h         |   2 +-
 mm/shmem.c                               | 139 +++++++++++++++++++++++++++++--
 mm/userfaultfd.c                         |  31 ++++---
 tools/testing/selftests/vm/Makefile      |   3 +
 tools/testing/selftests/vm/run_vmtests   |  11 +++
 tools/testing/selftests/vm/userfaultfd.c |  39 ++++++++-
 9 files changed, 237 insertions(+), 41 deletions(-)

-- 
1.9.1