bbswitch-dkms 0.8-3ubuntu1: bbswitch kernel module failed to build when doing apt-get full-upgrade

When doing apt-get full-upgrade this message appeared repeatedly on the terminal:

/usr/sbin/dkms: fork: retry: No child processes
/usr/sbin/dkms: fork: retry: No child processes
/usr/sbin/dkms: fork: retry: No child processes
/usr/sbin/dkms: fork: retry: Resource temporarily unavailable

And then this:

dpkg: error processing package linux-signed-image-4.4.0-4-generic (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of linux-signed-image-generic:
 linux-signed-image-generic depends on linux-signed-image-4.4.0-4-generic; however:
  Package linux-signed-image-4.4.0-4-generic is not configured yet.No apport report written because MaxReports is reached already

Maybe systemd related?

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: bbswitch-dkms 0.8-3ubuntu1
Uname: Linux 4.4.1-dvdme x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.19.4-0ubuntu2
Architecture: amd64
DKMSBuildLog:
 DKMS make.log for bbswitch-0.8 for kernel 4.4.0-4-generic (x86_64)
 Qui Fev 11 10:37:34 WET 2016
 make -C /lib/modules/4.4.0-4-generic/build M="$(pwd)" modules
 make: fork: Resource temporarily unavailable
DKMSKernelVersion: 4.4.0-4-generic
Date: Thu Feb 11 10:37:38 2016
InstallationDate: Installed on 2016-01-26 (15 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
PackageVersion: 0.8-3ubuntu1
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1
 apt 1.1.10
SourcePackage: bbswitch
Title: bbswitch-dkms 0.8-3ubuntu1: bbswitch kernel module failed to build
UpgradeStatus: Upgraded to xenial on 2016-02-11 (0 days ago)