pidns: make create_pid_namespace() accept parent pidns
pidns: make create_pid_namespace() accept parent pidns

create_pid_namespace() creates everything, but caller has to assign parent
pidns by hand, which is unnatural.  At the moment of call new ->level has
to be taken from somewhere and parent pidns is already available.

Signed-off-by: Alexey Dobriyan <b99bff5923d24d2fb8e844db9dac7cd59203da1d@gmail.com>
Cc: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@openvz.org>
Cc: "Eric W. Biederman" <8a741aa8cbd77ebc4a56ddb528ce9fd15d42f034@xmission.com>
Acked-by: Serge Hallyn <dd6cacb2d07f0aa354aa6e74c149a3580e5a1db1@us.ibm.com>
Acked-by: Sukadev Bhattiprolu <2ac48ee9b8f6042694a5d86ef56b8e10fe5327d1@linux.vnet.ibm.com>
Reviewed-by: WANG Cong <0f114804888b88d50037b04b42e57b858d851b87@gmail.com>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs