Comment 3 for bug 693594
Revision history for this message
| Nelson Elhage (nelhage) wrote Re: rmmod hangs if cgroup-bin is installed | #3 |
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(Get the code!)
The problem appears to be that the 'sysdefault' cgroup has a rt_runtime_us value of 0, and the stop_machine kthreads are getting created inside that cgroup (since the init script moves everything into the sysdefault cgroup), and so never get run.
The 'cpu' cgroup subsys will prevent moving RT tasks into a cgroup with rt_runtime_us == 0, but there's no mechanism to prevent the kernel from forking an RT thread inside such a cgroup.
Maverick "fixes" this by using the migration/N tasks for stop_machine, which come into existence before the cgroup init script, and so are prevented from moving into the sysdefault cgroup because they're already RT.