Comment # 11 on bug 1183568 from Michal Suchanek

Created attachment 848108 [details]
kmod debug script

Attaching tar archive with kmod debug script.

This will definitely slow down boot because it will make every kmod invocation
take at least one second but it will report if any invocation takes over one
second.

To use this

1) download 00aaakmodhack.tar
2) backup initrd
cp -a /boot/initrd-$(uname -r) /boot/initrd-$(uname -r).backup
3) unpack the module
tar -xvf 00aaakmodhack.tar -C /usr/lib/dracut/modules.d/
4) regenerate ramdisk
dracut -f

to remove

rm -r /usr/lib/dracut/modules.d/00aaakmodhack
mv /boot/initrd-$(uname -r).backup /boot/initrd-$(uname -r)

If a kmod process is stuck in the kernel for more than 1s the stack trace
should be shown in dmesg.

The other thing you can do is add the initcall_debug option to the kernel
commandline. It should tell you if the kernel is initializing a driver during
that time gap.