BACKPORT: userfaultfd: use per-vma locks in userfaultfd operations

All userfaultfd operations, except write-protect, opportunistically use
per-vma locks to lock vmas.  On failure, attempt again inside mmap_lock
critical section.

Write-protect operation requires mmap_lock as it iterates over multiple
vmas.

Link: https://lkml.kernel.org/r/20240215182756.3448972-5-lokeshgidra@google.com


Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Nicolas Geoffray <ngeoffray@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tim Murray <timmurray@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

(cherry picked from commit 867a43a3)
Conflicts:
	mm/userfaultfd.c

1. Resolve conflict in validate_dst_vma() due to absence of
   range_in_vma().
2. Use 'page' instead of 'folio' for BUG_ON on copy_from_user() failure
   in COPY ioctl.
3. Resolve conflict around mfill_file_over_size().
4. Resolve conflict in comment for __mcopy_atomic_hugetlb() due to
   function name change.
5. Resolve conflict due to use of 'flags' instead of 'mode' in
   __mcopy_atomic_hugetlb().
6. Use find_vma() and validate_dst_vma() in mwriteprotect_range()
   instead of find_dst_vma().

Bug: 320478828
Bug: 339845931
Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
(cherry picked from https://android-review.googlesource.com/q/commit:ce2896c0c6a5777721bdc703b1b89b1760e79854)
Merged-In: I6d5b7101218cb1b11329108c3f31f12bb1caebc6
Change-Id: I6d5b7101218cb1b11329108c3f31f12bb1caebc6