So "struct uts_namespace" can enjoy fine-grained SLAB debugging and
usercopy protection.

I'd prefer shorter name "utsns" but there is "user_namespace" already.

Link: http://lkml.kernel.org/r/20180228215158.GA23146@avx2Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Serge Hallyn <serge@hallyn.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>