cgroups: document the effect of attaching PID 0 to a cgroup
cgroups: document the effect of attaching PID 0 to a cgroup

Document that a pid of zero(0) can be used to refer to the current task
when attaching a task to a cgroup, as in the following usage:

	# echo 0 > /dev/cgroup/tasks

This is consistent with existing cpuset behavior.

Signed-off-by: Li Zefan <5dc16b054e85ffba6c8d314d8e55ae95dcab12a5@cn.fujitsu.com>
Acked-by: Paul Jackson <223b7f0fa34cb01a774d1d81d388f8c5f831b7fc@sgi.com>
Acked-by: Dhaval Giani <9e8a88f272eaf8af1eb7757146d1fb3d7f128182@linux.vnet.ibm.com>
Cc: Paul Menage <a4e32ff3ad614f63c49bddfcf4b7598c6857b687@google.com>
Cc: Balbir Singh <65a1aed538f36fed73d8c45e9ddfc585ce9f4abf@in.ibm.com>
Cc: Andrea Righi <243bc7e273657b4ad9a7ca12a3b3ad7b5bb1c892@gmail.com>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

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