I blacklisted a module in /etc/kdump.conf, why is it still loaded in the kdump environment?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux (RHEL) 6
    • kexec-tools-2.0.0-66 or newer

  • Red Hat Enterprise Linux (RHEL) 5
    • kexec-tools-1.102pre-138 or newer

Issue

  • I have blacklisted a module in file /etc/kdump.conf, why is it still loaded in the kdump environment? The blacklist line looks like this:
        blacklist iomemory_vsl

Resolution

It should be ensured that the kernel module is correctly written in /etc/kdump.conf. To verify this the name of the blacklisted module could be cut and pasted and be used with the find command:

find /lib/modules -name 'iomemory_vsl.ko'

In the example above no file was found - the blacklisted module was not correctly referred to in /etc/kdump.conf the following line has to be used:

blacklist iomemory-vsl

Root Cause

It is expected that the kdump-initrd still contains the blacklisted module. Its file /init is executed after loading the kexec kernel. This file is expected to not load the blacklisted module.

Diagnostic Steps

  • The generated kdump-initrd can be extracted using the following commands:
mkdir /tmp/tmp
cd /tmp/tmp
gunzip -c /boot/initrd-$(uname -r)kdump.img | \
    cpio --extract --verbose --make-directories --preserve
  • The blacklisted module(s) should appear in file /etc/blacklist-kdump.conf in the generated kdump-initrd.

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