Kernel hot patching.

Everything started in 2009, when two researchers from the MIT, J.Arnold and F.Kaashoek, wrote an academic paper about “Automatic Rebootless Kernel Updates”.
In this paper, they explained the state of the art in kernel hot patching and what approaches they took to improve it.
Being able to patch a kernel without rebooting brings several advantages:

• you avoid downtime in mission critical environments,
• you can apply security patches to your kernel without waiting for maintenance windows, this way, you avoid most of the security risks,
• you make the life of your administration and application support teams much better.

Some time later, the two researchers created a company called Ksplice with other MIT colleagues.
In 2011, the Oracle company bought this start-up and started selling patches through a subscription program.
Today, besides the Oracle Ksplice initiative, there is a race between the Suse and RedHat companies to integrate this feature in the Linux kernel and provide the related tools in their respective distribution.
Through kGraft, Suse has already a working solution waiting for Linux kernel acceptance when RedHat is still struggling to stabilize its own version. Whoever wins, a GPL solution should be available before the end of this year. This is a definitive achievement.

Additional information is available on the Red Hat Enterprise Linux Blog.