[Bug 1366829] Re: 7.4.4-1ubuntu2.1 makes rsyslogd to take all the CPU in OpenVZ

[Simon Déziel]

Just tested with an existing Trusty VZ and rsyslog (7.4.4-1ubuntu2.4)
keeps taking ~100% CPU. I had to re-enable the previous workaround of
disabling the imklog module loading.

The host is a 64bit Precise KVM running the OpenVZ upstream kernel from
their apt repo: 2.6.32-openvz-042stab102.8-amd64

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Title:
  7.4.4-1ubuntu2.1 makes rsyslogd to take all the CPU in OpenVZ

Status in rsyslog package in Ubuntu:
  Fix Released
Status in rsyslog source package in Trusty:
  Fix Committed
Status in rsyslog source package in Utopic:
  Fix Committed

Bug description:
  Test Case
  ---------
  * Install rsyslog 7.4.4-1ubuntu2.1 on an Ubuntu system that runs inside an OpenVZ container (If necessary, use ProxMox to quickly establish an OpenVZ container environment)
  * Verify that '$KLogPermitNonKernelFacility on' is set in /etc/rsyslog.conf
  * Restart rsyslog to make sure any changes to the binaries/config are picked up
  * Run 'top' and observe that the rsyslogd process is running at 100% CPU. When working properly, the rsyslogd process should generally be idle.

  ---------------------------------------------------------------------

  After updating  rsyslog from 7.4.4-1ubuntu2 to 7.4.4-1ubuntu2.1 the rsyslogd process started to take all the CPU on my machine.
  The modification made by this release is described in #1274444, it is the activation of KLogPermitNonKernelFacility option.
  I don't know exactly the effect of this option but it seems to have a permanent effect : even after downgrading the package or manually removing the option from /etc/rsyslog.conf the issue remains.
  My syslog is full of :
  Sep  8 10:28:40 sentry rsyslogd: imklog: error reading kernel log - shutting down: Bad file descriptor
  Sep  8 10:28:40 sentry rsyslogd: message repeated 498 times: [imklog: error reading kernel log - shutting down: Bad file descriptor]
  Sep  8 10:28:46 sentry rsyslogd-2177: rsyslogd[internal_messages]: 519517 messages lost due to rate-limiting
  I guess this is what causes the CPU load.

  I am running Ubuntu 14.04.1 LTS in an OpenVZ container on Proxmox 3.2. The kernel is 2.6.32-28-pve
  ---
  ApportVersion: 2.14.1-0ubuntu3.3
  Architecture: amd64DistroRelease: Ubuntu 14.04
  Package: rsyslog 7.4.4-1ubuntu2.1
  PackageArchitecture: amd64
  Tags:  trusty
  Uname: Linux 2.6.32-28-pve x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups:

  _MarkForUpload: True

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