[PATCH 8/8] Adds ability to move all threads in a process to a new cgroup atomically

[Li Zefan]

Paul Menage wrote:
> From: Ben Blum <bblum at google.com>
> 
> 
> Adds ability to move all threads in a process to a new cgroup atomically
> 
> This patch adds functionality that enables users to move all threads in a
> threadgroup at once to a cgroup by writing the tgid to the 'cgroup.procs'
> file. This current implementation makes use of a per-threadgroup rwsem that's
> taken for reading in the fork() path to prevent newly forking threads within
> the threadgroup from "escaping" while the move is in progress.
> 
> Cgroups subsystems that need to perform per-thread actions in their
> "attach" callback are (currently) responsible for doing their own
> synchronization, since this occurs outside of the critical section
> that locks against cloning within a thread group.
> 
> Signed-off-by: Ben Blum <bblum at google.com>
> Signed-off-by: Paul Menage <menage at google.com>
> 

Acked-by: Li Zefan <lizf at cn.fujitsu.com>