Unmounting a GFS2 filesystem appears to hang on RHEL 6

Issue

Red Hat Enterprise Linux Server 6, 7 (with the High Availability and Resilient Storage Add Ons)
A Global Filesystem 2(GFS2)

A Red Hat subscription provides unlimited access to our knowledgebase, tools, and much more.

Here are the common uses of Markdown.

Code blocks

~~~
Code surrounded in tildes is easier to read
~~~

Links/URLs

[Red Hat Customer Portal](https://access.redhat.com)