Linux: Tainted Kernels, Definitions, Checking and Diagnosing (Doc ID 395353.1)

Last updated on OCTOBER 20, 2022

Applies to:

Linux OS - Version 2.4 to 2.6
Oracle Cloud Infrastructure - Version N/A and later
Linux Itanium
Linux x86-64
Linux x86
Linux ItaniumLinux x86-64Linux x86

Purpose

Describe the terms "Kernel Tainting" and "Tainted Kernel" to assist the determination the implications of running a tainted kernel.

Scope

Allow Linux System Administrators to determine the kernel status with respect to tainting to help readers to see whether the Linux configuration is supportable.

Details

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In this Document

What is Kernel Tainting?

The Linux Kernel Tainting Mechanism

Checking for Kernel Tainting

The taint status of the kernel not only indicates whether or not the kernel has been tainted but also indicates what type(s) of event caused the kernel to be marked as tainted. This information is encoded through single-character flags in the string following "Tainted:" in a kernel error message.

The 'lsmod' command in Enterprise Linux 3 reports some information about modules tainting the kernel:

The output will state 'Not tainted' if the kernel is not tainted as in the following example:

Note that, in Enterprise Linux 4, the 'lsmod' command does not provide that information.

If there is an OOPS output, it will contain the kernel tainting information:

The kernel parameter kernel.tainted (/proc/sys/kernel/tainted) is a bit-encoded field that shows the kinds of tainting being encountered. The example below tells us that 3 modules are tainting the kernel.

A non-tainted kernel will have value 0.

From the OOPS output or lsmod (RHEL3) the output if the kernel is tainted can look as below:

How to Find Whether a Module is Tainting Kernel or Not?

The kernel is tainted by a Proprietary module and there is also some module force loaded. If we want to check about the "gab module":

Checking the license field tells us that this module is causing the P flag. But note that there might be others.

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