I've bisected the differences from Ubuntu stock kernel and pf4+ kernel configuration and I've found that the error is triggered by tue CONFIG_SCHED_AUTOGROUP setting. Fortunately it can be disabled at boot time adding the "noautogroup" parameter to grub.
With the "noautogroup" the Ubuntu stock kernel 3.13.0-35-generic boots without any problem. I've tried several times.
I've bisected the differences from Ubuntu stock kernel and pf4+ kernel configuration and I've found that the error is triggered by tue CONFIG_ SCHED_AUTOGROUP setting. Fortunately it can be disabled at boot time adding the "noautogroup" parameter to grub.
With the "noautogroup" the Ubuntu stock kernel 3.13.0-35-generic boots without any problem. I've tried several times.