Applications or scripts fail while trying to open /dev/mem

Issue

• When running scripts on our RHEL system, we are getting the below error:

ERROR: Failed to open /dev/mem

• When running mcelog even as root, it can't open /dev/mem:

mcelog: Cannot open /dev/mem for DMI decoding: Permission denied

• Permissions seem correct on this device file:

[root@~]# ls -la /dev/mem
crw-r----- 1 root kmem 1, 1 Jan  4 17:07 /dev/mem