df: `/sys/kernel/debug': Function not implemented

[latimerio]

Kernel 3.2.0-85-generic #122-Ubuntu SMP Tue May 26 16:14:57 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
always gives `/sys/kernel/debug': Function not implemented when giving a "df" command.
We have 4 machines running that kernel and all show the same issue.
All other 100+ Ubuntu 12 and 14 hosts that we have don't show the issue.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: coreutils 8.13-3ubuntu3.3
ProcVersionSignature: Ubuntu 3.2.0-85.122-generic 3.2.69
Uname: Linux 3.2.0-85-generic x86_64
ApportVersion: 2.0.1-0ubuntu17.9
Architecture: amd64
Date: Mon Jun 15 10:14:31 2015
MarkForUpload: True
SourcePackage: coreutils
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Ajax4Hire (ajax4hire)]

Just updated kernel to: Linux 3.2.0-86-generic-pae
thru the update-manager.
after install, I get:
[baseuser@Cisco-SA00 /boot]$ sudo df

df: `/sys/kernel/debug': Function not implemented

Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda3 955997932 65861436 841574628 8% /
blah...blah...blah