Christian Brauner ef2c41cf38 clone3: allow spawning processes into cgroups
This adds support for creating a process in a different cgroup than its
parent. Callers can limit and account processes and threads right from
the moment they are spawned:
- A service manager can directly spawn new services into dedicated
  cgroups.
- A process can be directly created in a frozen cgroup and will be
  frozen as well.
- The initial accounting jitter experienced by process supervisors and
  daemons is eliminated with this.
- Threaded applications or even thread implementations can choose to
  create a specific cgroup layout where each thread is spawned
  directly into a dedicated cgroup.

This feature is limited to the unified hierarchy. Callers need to pass
a directory file descriptor for the target cgroup. The caller can
choose to pass an O_PATH file descriptor. All usual migration
restrictions apply, i.e. there can be no processes in inner nodes. In
general, creating a process directly in a target cgroup adheres to all
migration restrictions.

One of the biggest advantages of this feature is that CLONE_INTO_GROUP does
not need to grab the write side of the cgroup cgroup_threadgroup_rwsem.
This global lock makes moving tasks/threads around super expensive. With
clone3() this lock is avoided.

Cc: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: cgroups@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2020-02-12 17:57:51 -05:00
..
2020-02-09 12:11:12 -08:00
2019-11-27 11:42:01 -08:00
2020-02-11 16:39:18 -08:00
2019-12-18 18:07:31 +01:00
2019-07-08 18:55:42 -07:00
2019-07-08 18:55:42 -07:00
2020-01-03 11:17:14 -08:00
2020-01-09 13:23:40 +01:00
2020-02-09 16:05:50 -08:00
2019-12-04 19:44:14 -08:00
2020-01-08 16:32:55 +00:00
2020-01-14 12:20:48 +01:00
2019-12-11 16:37:02 +08:00
2020-01-13 21:49:36 +01:00
2019-12-04 15:18:39 +01:00
2019-12-18 18:07:31 +01:00
2019-07-08 19:36:47 -07:00
2019-07-08 19:36:47 -07:00