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SubjectRe: [RFC][PATCH 2/3] CGroups: Use hierarchy_mutex in memory controller
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On Wed, Dec 10, 2008 at 4:49 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@jp.fujitsu.com> wrote:
>
> an operation like rmdir() in somewhere.
> hierarchy_lock for A (acquired)
> hierarchy_lock for B (waiting)
>
> in subsys A.
> mmap_sem (acquired)
> hierarchy_lock for A (waiting)
> in subsys B.
> hierarchy_lock for B (aquired)
> mmap_sem (waiting)
>

That's a valid deadlock - you'd need to require the mmap_sem nests
either inside all hierarchy_mutexes or else outside all of them.

Paul


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