Bug 789630

Summary: dm_mod aka dm-mod.ko is loaded by default but i not use RAID or LVM
Product: Red Hat Enterprise Linux 6 Reporter: xset1980
Component: device-mapperAssignee: LVM and device-mapper development team <lvm-team>
Status: CLOSED NOTABUG QA Contact: Cluster QE <mspqa-list>
Severity: low Docs Contact:
Priority: unspecified    
Version: 6.1CC: agk, dwysocha, heinzm, jbrassow, mbroz, prajnoha, prockai, thornber, zkabelac
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2012-02-11 21:49:00 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:

Description xset1980 2012-02-11 21:10:56 UTC
Description of problem:

dm_mod is loaded in SL6.1, but i no use RAID or LVM.
The script /etc/rc.d/rc.sysinit contain:

# Device mapper & related initialization
if ! __fgrep "device-mapper" /proc/devices >/dev/null 2>&1 ; then
       modprobe dm-mod >/dev/null 2>&1
fi

And, my /proc/devices contain 253 device mapper device, but, i no use RAID or LVM, so, is a kernel or device-mapper bug?


Version-Release number of selected component (if applicable):

SL6.1, kernel 2.6.32-220.4.1.el6.i686

How reproducible:

Always

Steps to Reproduce:
1.
2.
3.
  
Actual results:

The kernel module dm-mod.ko is loaded by default, but the system not use RAID or LVM


Expected results:

No load dm_mod


Additional info:

Comment 2 Milan Broz 2012-02-11 21:49:00 UTC
No it is not a bug.

Some kernel modules all loaded to ensure that storage stack always contains
this functionality - if you plug in disk with e.g. LUKS (encrypted flash) or
LVM it can be then handled properly. And several RHEL system scripts require
dm-ioctl
functionality (mkinitrd for kernel upgrade for example).

If you have some "hardened" or tuned installation, you can rmmod that later of
course but you can expect some warning later.

In /proc/devices is just registered device type, not a real mapped device (for
real mapped device see "dmsetup table" - it should be empty in your case.

Comment 3 Alasdair Kergon 2012-02-12 00:28:49 UTC
*** Bug 789639 has been marked as a duplicate of this bug. ***

Comment 4 Alasdair Kergon 2012-02-12 00:31:26 UTC
As Milan says, if you know for certain you won't need it later in the life of the system and it bothers you, just 'rmmod' the module at the end of initialisation.