Change reclaim to respect cpuset.mems_effective during demotion when
possible. Presently, reclaim explicitly ignores cpuset.mems_effective
when demoting, which may cause the cpuset settings to violated.

Implement cpuset_node_allowed() to check the cpuset.mems_effective
associated wih the mem_cgroup of the lruvec being scanned. This only
applies to cgroup/cpuset v2, as cpuset exists in a different hierarchy
than mem_cgroup in v1.

This requires renaming the existing cpuset_node_allowed() to be
cpuset_current_now_allowed() - which is more descriptive anyway - to
implement the new cpuset_node_allowed() which takes a target cgroup.

v4:
- explicitly expect v1 instead of checking for empty effective_mems.
  this was the case anyway since cpuset and mem_cgroup are in different
  heirarchy in v1.
- update docs to reflect this
- rcu_read_lock instead of taking a global lock.
- cpuset header fixup when compiled out.

Gregory Price (2):
  cpuset: rename cpuset_node_allowed to cpuset_current_node_allowed
  vmscan,cgroup: apply mems_effective to reclaim

 .../ABI/testing/sysfs-kernel-mm-numa          | 16 +++++---
 include/linux/cpuset.h                        |  9 +++-
 include/linux/memcontrol.h                    |  6 +++
 kernel/cgroup/cpuset.c                        | 30 +++++++++++++-
 mm/memcontrol.c                               |  6 +++
 mm/page_alloc.c                               |  4 +-
 mm/vmscan.c                                   | 41 +++++++++++--------
 7 files changed, 84 insertions(+), 28 deletions(-)

-- 
2.49.0