How is the Linux kernel tested ?

Question

How do the Linux kernel developers test their code locally and after they have it committed? Do they use some kind of unit testing, build automation? test plans?

Answer 1

Naturally, the kernel itself and its parts are tested prior to the release, but these tests cover only the basic functionality. There are some testing systems which perform testing of Linux Kernel:

The Linux Test Project (LTP) delivers test suites to the open source community that validate the reliability and stability of Linux. The LTP test suite contains a collection of tools for testing the Linux kernel and related features. https://github.com/linux-test-project/ltp

Autotest -- a framework for fully automated testing. It is designed primarily to test the Linux kernel, though it is useful for many other purposes such as qualifying new hardware, virtualization testing, and other general user space program testing under Linux platforms. It's an open-source project under the GPL and is used and developed by a number of organizations, including Google, IBM, Red Hat, and many others. http://autotest.github.io/

Also there are certification systems developed by some major GNU/Linux distribution companies. These systems usually check complete GNU/Linux distributions for compatibility with hardware. There are certification systems developed by Novell, Red Hat, Oracle, Canonical, Google.

There are also systems for dynamic analysis of Linux kernel:

Kmemleak is a memory leak detector included in the Linux kernel. It provides a way of detecting possible kernel memory leaks in a way similar to a tracing garbage collector with the difference that the orphan objects are not freed but only reported via /sys/kernel/debug/kmemleak.

Kmemcheck traps every read and write to memory that was allocated dynamically (i.e. with kmalloc()). If a memory address is read that has not previously been written to, a message is printed to the kernel log. Also is a part of Linux Kernel

Fault Injection Framework (included in Linux kernel) allows for infusing errors and exceptions into an application's logic to achieve a higher coverage and fault tolerance of the system.