After more than six years of long-term support, the Linux 4.9 kernel series has finally reached end-of-life in the newly released Linux 4.9.337 update. The Linux 4.9 kernel is now appropriately marked as EOL on the kernel.org website, which means it will no longer receive maintenance and security updates.

Well-known kernel developer Greg Kroah-Hartman announced in the kernel mail announcement that Linux kernel 4.9 will no longer be supported, urging users to upgrade to a newer LTS series, such as Linux kernel 4.14, which will be supported until January 2024, or the latest and greatest Linux kernel 6.1, which should be an LTS release in 2022 (but hasn’t been officially announced yet), is supported for at least two years.

Note that this is the last 4.9.y kernel we released. This kernel version is now obsolete, you should at least move to version 4.14.y.

6.1.y is a better choice.

Linux kernel 4.9 was released on December 11, 2016, and it brought share scope and copy-on-write support for the XFS filesystem, a hardware latency tracker for detecting firmware-induced latency, support for the Greybus bus from Project Ara support, more efficient BPF analyzer, new optional BBR TCP congestion control algorithm, virtual mapped kernel stack, and more.

Due to its Long Term Support (LTS) status, Linux 4.9 is likely to be used by large companies in production environments, such as mass production devices/hardware powered by the Linux 4.9 operating system.