On Wed, 30 Oct 2024 at 00:25, Tejun Heo <tj@xxxxxxxxxx> wrote: > If that can't be done, we can add a mechanism to ignore these tasks when > determining when a cgroup is frozen provided that this doesn't affect the > snapshotting (ie. when taking a snapshot of frozen cgroup, activities from > the kthreads won't corrupt the snapshot). What do these kvm kthreads actually do? So one of the use cases in systemd is to freeze the entire user session before suspend, so that the encryption key for the home directory (homed) can be removed from memory (until after resume, after the user has typed the password in the screen lock again), without the risk of having programs trying to access the now inaccessible files in the home directory. So if qemu is frozen, but the kvm kthread is not and somehow lets the VM or part of it still run and use files (e.g.: write to the disk image that is stored in the homedir) that are now inaccessible, that would be problematic for this use case.
