On Wed, 2020-03-04 at 11:42 -0500, Tejun Heo wrote:
> [SNIP]
> 
> Right now, the situation isn't great with dm. When pagecache
> writebacks go through dm, in some cases including dm-crypt, the cgroup
> ownership information is completely lost and all writes end up being
> issued as the root cgroup, so it breaks down when dm is in use.

Fair enough.

> In the longer term, what we wanna do is controlling at physical
> devices (sda here) and then updating dm so that it can maintain and
> propagate the ownership correctly but we aren't there yet.

Perfect, so what I am seeing is really just a small systemd bug. Thansk
for confirming, I'll submit a patch to fix it.

Benjamin