I would suggest you to open the SR with oracle to see the updated kernel support your version.
why are you trying to update the kernal right now after installing the rac? Shouldn't it be done before installation?
Thanks for your hint.
Yes, I'm trying to update the kernel after the installation. This will happen in future during normal operations, too.
That version of the kenel is bad. We saw the same thing. Try 3.10.0-514.21.1.el7 instead. Hopefully there will be a fix for the 3.10.0-514.21.2.el7 kernel soon.