Re: [PATCH cgroup/for-4.4] cgroup: fix race condition around termination check in css_task_iter_next()

From: Tejun Heo
Date: Wed Oct 28 2015 - 23:02:37 EST

On Tue, Oct 27, 2015 at 05:45:04PM +0900, Tejun Heo wrote:
> css_task_iter_next() checked @it->cur_task before grabbing
> css_set_lock and assumed that the result won't change afterwards;
> however, tasks could leave the cgroup being iterated terminating the
> iterator before css_task_lock is acquired. If this happens,
> css_task_iter_next() tries to calculate the current task from NULL
> cg_list pointer leading to the following oops.

Applied to cgroup/for-4.4. Thanks.

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