On Mon, Mar 20, 2023 at 01:15:04AM +0000, Cai Xinchen wrote:
I am very sorry. My gcc version is 7.5 and it does not report error.
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")
Changes in v2: * Add #include <linux/cpu.h> in kernel/cgroup/cgroup.c to avoid some compile error. * Exchange get_online_cpus() location in cpuset_attach to keep cpu_hotplug_lock->cpuset_mutex order, although it will be remove by ("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock")
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 | 50 +++++++++++++++++++++++++++++++++++---- kernel/cgroup/cpuset.c | 25 ++++++++++++-------- 4 files changed, 67 insertions(+), 19 deletions(-)
Now queued up, thanks.
greg k-h