On 9/6/22 14:30, Tejun Heo wrote:
Hello,
(cc'ing Waiman in case he has a better idea)
On Mon, Sep 05, 2022 at 04:22:29PM +0800, Jing-Ting Wu wrote:
https://lore.kernel.org/lkml/YvrWaml3F+x9Dk+T@xxxxxxxxxxxxxxx/ is for
fix cgroup_threadgroup_rwsem <-> cpus_read_lock() deadlock.
But this issue is cgroup_threadgroup_rwsem <-> cpuset_rwsem deadlock.
If I'm understanding what you're writing correctly, this isn't a deadlock.
The cpuset_hotplug_workfn simply isn't being woken up while holding
cpuset_rwsem and others are just waiting for that lock to be released.
I believe it is probably a bug in the scheduler core code.
__set_cpus_allowed_ptr_locked() calls affine_move_task() to move to a
random cpu within the new set allowable CPUs. However, if migration is
disabled, it shouldn't call affine_move_task() at all. Instead, I would
suggest that if the current cpu is within the new allowable cpus, it
should just skip doing affine_move_task(). Otherwise, it should fail
__set_cpus_allowed_ptr_locked().
My 2 cents.
Cheers,
Longman
