NetworkManager fails to start

Hi,

The commit 591a22c14d3f ("proc: Track /proc/$pid/attr/ opener mm_struct") that we got in v5.13-rc6 broke our regression to pieces. The NIC interfaces fail to start when using NetworkManager.

There is nothing in dmesg except error that NetworkManager failed to start.

Our setups are: * VMs with virtio-net NICs * Fedora 29

The revert fixes the issue and VMs boot with network working.

Thanks