[PATCH v2 00/10] cpuset: implement sane hierarchy behaviors

[Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>]

v1 -> v2:

- add documentation in include/linux/cgroup.h
- drop rcu_read_lock() before calling update_task_nodemask() when iterating
cpuset hierarchy

======================================

Currently some cpuset behaviors are not friendly when cpuset is co-mounted
with other cgroup controllers.

Now with this patchset if cpuset is mounted with sane_behavior option, it
behaves differently:

- Tasks will be kept in empty cpusets when hotplug happens and take masks
of ancestors with non-empty cpus/mems, instead of being moved to an ancestor.

- A task can be moved into an empty cpuset, and again it takes masks of
ancestors, so the user can drop a task into a newly created cgroup without
having to do anything for it.

As tasks can reside in empy cpusets, here're some rules:

- They can be moved to another cpuset, regardless it's empty or not.

- Though it takes masks from ancestors, it takes other configs from the
empty cpuset.

- If the ancestors' masks are changed, those tasks will also be updated
to take new masks.

Li Zefan (10):
      cpuset: remove redundant check in cpuset_cpus_allowed_fallback()
      cpuset: cleanup guarantee_online_{cpus|mems}()
      cpuset: remove unnecessary variable in cpuset_attach()
      cpuset: remove cpuset_test_cpumask()
      cpuset: re-structure update_cpumask() a bit
      cpuset: record old_mems_allowed in struct cpuset
      cpuset: introduce effective_{cpumask|nodemask}_cpuset()
      cpuset: allow to keep tasks in empty cpusets
      cpuset: allow to move tasks to empty cpusets
      cpuset: fix to migrate mm correctly in a corner case

--
 include/linux/cgroup.h |   7 +
 kernel/cpuset.c        | 342 ++++++++++++++++++++++++++++++++++---------------
 2 files changed, 247 insertions(+), 102 deletions(-)