Also bugreport is really helpful:
https://bugzilla.redhat.com/show_bug.cgi?id=1161491
Here is copy/paste what bug reporter has found out:
I then freshly installed Fedora 20 and tested some kernels:
3.17.2-300.fc21 on updated F20 : doesn't work
3.17.0-1.vanilla.mainline.knurd.1.fc20.x86_64 : doesn't work
3.17.2-200.vanilla.stable.knurd.1.fc20.x86_64 : works
I then tested vanilla kernels on a new F21 installation, with the
following results:
3.17.1-302.fc21.x86_64 : doesn't work
3.17.2-300.fc21.x86_64 : doesn't work
3.17.0-1.vanilla.mainline.knurd.1.fc21.x86_64 : doesn't work
3.17.2-300.vanilla.stable.knurd.1.fc21.x86_64 : doesn't work
I don't exactly know what to do with this information, especially
since 3.17.1 and 3.17.2-300 don't seem to work, but
3.17.2-200.vanilla.stable does.