Excessive warnings regarding stat()ing of cgroup filesystems

[Gavin Panella]

Every invocation of lsof results in 24 lines of warnings being printed to stderr. This is excessive and, at least for my use cases, not useful information.

$ mkdir foo && lsof +D foo
lsof: WARNING: can't stat() tmpfs file system /run/lxcfs/controllers
      Output information may be incomplete.
lsof: WARNING: can't stat() cgroup file system /run/lxcfs/controllers/name=systemd
      Output information may be incomplete.
lsof: WARNING: can't stat() cgroup file system /run/lxcfs/controllers/cpu,cpuacct
      Output information may be incomplete.
lsof: WARNING: can't stat() cgroup file system /run/lxcfs/controllers/pids
      Output information may be incomplete.
lsof: WARNING: can't stat() cgroup file system /run/lxcfs/controllers/cpuset
      Output information may be incomplete.
lsof: WARNING: can't stat() cgroup file system /run/lxcfs/controllers/net_cls,net_prio
      Output information may be incomplete.
lsof: WARNING: can't stat() cgroup file system /run/lxcfs/controllers/devices
      Output information may be incomplete.
lsof: WARNING: can't stat() cgroup file system /run/lxcfs/controllers/freezer
      Output information may be incomplete.
lsof: WARNING: can't stat() cgroup file system /run/lxcfs/controllers/perf_event
      Output information may be incomplete.
lsof: WARNING: can't stat() cgroup file system /run/lxcfs/controllers/hugetlb
      Output information may be incomplete.
lsof: WARNING: can't stat() cgroup file system /run/lxcfs/controllers/memory
      Output information may be incomplete.
lsof: WARNING: can't stat() cgroup file system /run/lxcfs/controllers/blkio
      Output information may be incomplete.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: lsof 4.89+dfsg-0.1
ProcVersionSignature: Ubuntu 4.3.0-5.16-generic 4.3.3
Uname: Linux 4.3.0-5-generic x86_64
ApportVersion: 2.19.3-0ubuntu3
Architecture: amd64
CurrentDesktop: Unity
Date: Thu Jan 14 21:12:45 2016
InstallationDate: Installed on 2014-03-16 (668 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Alpha amd64 (20140316)
SourcePackage: lsof
UpgradeStatus: Upgraded to xenial on 2015-11-22 (52 days ago)

[Launchpad Janitor (janitor)]

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