Kgraft allows Linux to receive hotfixes without needing a reboot

SUSE Linux has released the code for kGraft, a module which can be used to patch a running Linux kernel. The company had promised to make the release this month. The head of the company’s kernel development, Vojtech Pavlik, said in a media release: “Originally a research project from SUSE Labs, kGraft has quickly shown its promise as a live patching Linux tool for enterprise users.”

Nobody loves downtime or reboots — especially not Suse. But the Linux engineers at Suse didn’t just sit there and grind their teeth over forced reboots after a kernel patch; they went out and did something about it. That something was Kgraft, a technology that allows live hotfixes to be applied to the Linux kernel without a reboot . Now Suse’s decided torelease that technology into the wild as an open source project, under the GPLv3 license. The core idea behind Kgraft is to take advantage of functionality that already exists in the Linux kernel. An article at Linux.com describes the technique as “[using] an ftrace-like approach to replace whole functions in the Linux kernel with fixed variants.” This approach involves modifying the kernel, so one can’t apply Kgraft to an existing kernel; the kernel has to be patched with Kgraft beforehand.