This seems strange. Does it only happen with that kernel version?
Things I can think of are that you might be able to change the kernel log level by editing the boot parameters in GRUB, to reduce how much it is printing to the log. Or, you could try making some sort of looping shell script or daemon that deletes the log file every 5 minutes, or when it reaches a certain size.
Although, neither of those would address the underlying cause.
