When using RHEL 7 with option cards, system may generate call trace "Bug soft lockup - CPU#N stuck for NNs." The lockup is caused by the parallel loading of driver modules by multiple systemd-udevd threads.
Affected software:
Red Hat Enterprise Linux 7.0
Releases 1.0 and later
Workaround:
To only allow single udev children to run, add udev.children-max=1 rd.udev.children-max=1 into kernel command in grub configuration.