[SOLVED] Does /proc/modules only list kernel modules that are correctly loaded?

Issue

The red hat documentation regarding this file is vague. At first, it states that:

This file displays a list of all modules loaded into the kernel

But then later in the doc, it says:

The third column lists how many instances of the module are currently loaded. A value of zero represents an unloaded module.

So my questions are:

1. If the third value for a module is 0, does this mean that it is no longer loaded in the kernel right now? If so, then why do all of them still have a kernel address?

2. If /proc/modules only shows the currently loaded kernel modules, how can I find the list of all the kernel modules that will get loaded automatically after boot?

Solution

According to /kernel/module/procfs.c this third value is not the number of instances, but the reference count of the module (module_refcount).

If a module has a reference count > 0 than it can't be unload safely (other modules expect it to be there), but if the reference count is 0 the module can be unloaded, but it's still loaded as of now.

Don't know why this documentation got it wrong.

2. A systemd service called systemd-modules-load.service loads modules at boot time. here is some documentation that shows how it works and where to look. However, there is a different service for systems withoud systemd and I'm pretty sure you have some other ways of loading a modules.

Answered By - LITzman

Answer Checked By - Senaida (WPSolving Volunteer)