cgroup: make sure a parent css isn't freed before its children

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commit 8bb5ef79bc upstream.

There are three subsystem callbacks in css shutdown path -
css_offline(), css_released() and css_free().  Except for
css_released(), cgroup core didn't guarantee the order of invocation.
css_offline() or css_free() could be called on a parent css before its
children.  This behavior is unexpected and led to bugs in cpu and
memory controller.

The previous patch updated ordering for css_offline() which fixes the
cpu controller issue.  While there currently isn't a known bug caused
by misordering of css_free() invocations, let's fix it too for
consistency.

css_free() ordering can be trivially fixed by moving putting of the
parent css below css_free() invocation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Tejun Heo 2016-01-21 15:32:15 -05:00 • committed by Greg Kroah-Hartman

parent 36abe7272a

commit 3c6266d57c

1 changed files with 4 additions and 3 deletions

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kernel/cgroup.c

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