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[Launchpad Bug Tracker <1284731@xxxxxxxxxxxxxxxxxx>]

This bug was fixed in the package linux-grouper - 3.1.10-8.28

---------------
linux-grouper (3.1.10-8.28) trusty; urgency=low

  [ Andy Whitcroft ]

  * [Config] CONFIG_RT_GROUP_SCHED=n
    - LP: #1284731
 -- Andy Whitcroft <apw@xxxxxxxxxxxxx>   Wed, 26 Feb 2014 12:43:34 +0000

** Changed in: linux-manta (Ubuntu)
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1284731

Title:
  Please turn off CONFIG_RT_GROUP_SCHED in all our kernels

Status in “linux” package in Ubuntu:
  Fix Released
Status in “linux-flo” package in Ubuntu:
  Fix Released
Status in “linux-goldfish” package in Ubuntu:
  Fix Released
Status in “linux-grouper” package in Ubuntu:
  Fix Released
Status in “linux-maguro” package in Ubuntu:
  Won't Fix
Status in “linux-mako” package in Ubuntu:
  Fix Released
Status in “linux-manta” package in Ubuntu:
  Fix Released

Bug description:
  Hello,

  We've just had a rather length chat in #ubuntu-touch about some
  problems related to rtkit and pulseaudio on the phone and then on any
  trusty machine.

  It turns out that since we now put all users in their own cpu cgroup,
  rt_runtime_us is set to 0 which prevents any of those tasks from ever
  getting real-time priority. There are various ways we could try to
  hack around that in logind, basically manually inheriting a sane
  value, etc...

  
  However it turns out that we never use those cgroup bits and that they are concerned as some kind of security problems when users have access to those. So given that, it seems like the best course of action is just to turn off CONFIG_RT_GROUP_SCHED in all our kernels. This will revert us to a pre-trusty behaviour where users can't set the rt priority but rtkit (a privileged daemon) can, so pulseaudio and the rest of those software should be happy again.

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