We have a deadlock problem which can be solved by commit 4f7e7236435ca
("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock").
However, it makes lock order of cpus_read_lock and cpuset_mutex
wrong in v4.19. The call sequence is as follows:
cgroup_procs_write()
cgroup_procs_write_start()
get_online_cpus(); // cpus_read_lock()
percpu_down_write(&cgroup_threadgroup_rwsem)
cgroup_attach_task
cgroup_migrate
cgroup_migrate_execute
ss->attach (cpust_attach)
mutex_lock(&cpuset_mutex)
it seems hard to make cpus_read_lock is locked before
cgroup_threadgroup_rwsem and cpuset_mutex is locked before
cpus_read_lock unless backport the commit d74b27d63a8beb
("cgroup/cpuset: Change cpuset_rwsem and hotplug lock order")
Juri Lelli (1):
cgroup/cpuset: Change cpuset_rwsem and hotplug lock order
Tejun Heo (1):
cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock
Tetsuo Handa (1):
cgroup: Add missing cpus_read_lock() to cgroup_attach_task_all()
include/linux/cpuset.h | 8 +++----
kernel/cgroup/cgroup-v1.c | 3 +++
kernel/cgroup/cgroup.c | 49 +++++++++++++++++++++++++++++++++++----
kernel/cgroup/cpuset.c | 25 ++++++++++++--------
4 files changed, 66 insertions(+), 19 deletions(-)
--
2.17.1
