kernel-packages team mailing list archive

[Stéphane Graber <stgraber@xxxxxxxxxxxx>]

Public bug reported:

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.

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: bot-stop-nagging

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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:
  New

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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