[Devel] [PATCH] sched: CPU hotplug race vs. set_cpus_allowed()

[Kirill Korotaev]

There is a race between set_cpus_allowed()
and move_task_off_dead_cpu().
__migrate_task() doesn't report any err code, so
task can be left on its runqueue if its cpus_allowed mask
changed so that dest_cpu is not longer a possible target.
Also, chaning cpus_allowed mask requires rq->lock being held.

Changes from original post according to to Con Colivas notes:
- added comment
- cleanup code a bit

Signed-Off-By: Kirill Korotaev <dev at openvz.org>
Acked-By: Ingo Molnar <mingo at elte.hu>

Kirill
P.S. against 2.6.17-mm1
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