On Fri, Mar 03, 2023 at 04:50:47AM +0000, Cai Xinchen wrote:
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
Now queued up, thanks.
greg k-h