commit 06f4e948 upstream.

A new task inherits cpus_allowed and mems_allowed masks from its parent,
but if someone changes cpuset's config by writing to cpuset.cpus/cpuset.mems
before this new task is inserted into the cgroup's task list, the new task
won't be updated accordingly.
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>