userfaultfd: hugetlbfs: add UFFDIO_COPY support for shared mappings

When userfaultfd hugetlbfs support was originally added, it followed the
pattern of anon mappings and did not support any vmas marked VM_SHARED.
As such, support was only added for private mappings.

Remove this limitation and support shared mappings.  The primary
functional change required is adding pages to the page cache.  More subtle
changes are required for huge page reservation handling in error paths.  A
lengthy comment in the code describes the reservation handling.

[[email protected]: update]
  Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Mike Kravetz <[email protected]>
Reviewed-by: Andrea Arcangeli <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: "Dr. David Alan Gilbert" <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Pavel Emelyanov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions