Re: cgroup scheduling: Adding kthreadd to a non-RT cgroup candeadlock the kernel

From: Peter Zijlstra
Date: Wed Jan 05 2011 - 10:18:15 EST


On Wed, 2011-01-05 at 10:02 -0500, Nelson Elhage wrote:
> Ok. I bothered reporting this here since the kernel /does/ try to prevent you
> from shooting yourself in the foot in related ways, by moving existing
> SCHED_FIFO tasks into a cgroup without any RT runtime, so I figured it might
> make sense to add a check here. libcgroup, for example, will try to move all
> processes into a default cgroup, ignoring errors, and relies on the kernel to
> prevent it from shooting itself in the foot.
>
> It sounds like you consider that behavior a bug, though, so I'll go report this
> bug there.

Right, so we try to catch obvious cases, but its near impossible to
catch all cases.

And its not only the scheduler controller, I bet you can get into
trouble with some of the other controllers as well.
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