Over the past couple of months, the Linux kernel developers worked hard to mitigate these nasty bugs, and they released several updates to the all supported Linux kernel series, which, by now, most GNU/Linux distributions have adopted.
Greg Kroah-Hartman also noted the fact that if your GNU/Linux distribution doesn’t have these new Linux kernel updates, which contain all the fixes to mitigate the Meltdown vulnerability on the x86 architecture, you should consider changing it right now. He also recommended users to run the latest Linux 4.14 release (Linux kernel 4.14.12 at the moment of writing) on their Linux-based operating systems.