On Tue, Dec 14, 2021 at 4:13 PM Vipin Sharma <vipinsh@xxxxxxxxxx> wrote: > > VM worker kthreads can linger in the VM process's cgroup for sometime > after KVM temrinates the VM process. > > KVM terminates the worker kthreads by calling kthread_stop() which waits > on the signal generated by exit_mm() in do_exit() during kthread's exit. > However, these kthreads are removed from the cgroup using cgroup_exit() > call which happens after exit_mm() in do_exit(). A VM process can > terminate between the time window of exit_mm() to cgroup_exit(), leaving > only worker kthreads in the cgroup. > > Moving worker kthreads back to the original cgroup (kthreadd_task's > cgroup) makes sure that cgroup is empty as soon as the main VM process > is terminated. > > Signed-off-by: Vipin Sharma <vipinsh@xxxxxxxxxx> > --- > virt/kvm/kvm_main.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) Hello Off-topic, can this kvm worker_thread and the thread to do async pagefault be possibly changed to use something like io_uring's IOWQ (fs/io-wq.c) created by create_io_thread()? So that every resource the threads used are credited to the process of the vm. Thanks Lai
