cgroup/cpuset: Change cpuset_rwsem and hotplug lock order

cpuset_rwsem is going to be acquired from sched_setscheduler() with a
following patch. There are however paths (e.g., spawn_ksoftirqd) in
which sched_scheduler() is eventually called while holding hotplug lock;
this creates a dependecy between hotplug lock (to be always acquired
first) and cpuset_rwsem (to be always acquired after hotplug lock).

Fix paths which currently take the two locks in the wrong order (after
a following patch is applied).

Change-Id: I5589d6cf0f0709bdeb083a08e56d64ebcb90dac9
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: mathieu.poirier@linaro.org
Cc: rostedt@goodmis.org
Cc: tj@kernel.org
Cc: tommaso.cucinotta@santannapisa.it
Link: https://lkml.kernel.org/r/20190719140000.31694-7-juri.lelli@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Git-commit: d74b27d63a8bebe2fe634944e4ebdc7b10db7a39
[snaseem@codeaurora.org: Resolve trivial merge conflicts and
 change cpuset_mutex and hotplug lock order]
Signed-off-by: Shadab Naseem <snaseem@codeaurora.org>