Commit fa06235b authored Mar 01, 2016 by Vladimir Davydov Committed by Tejun Heo Mar 01, 2016

cgroup: reset css on destruction

An associated css can be around for quite a while after a cgroup
directory has been removed. In general, it makes sense to reset it to
defaults so as not to worry about any remnants. For instance, memory
cgroup needs to reset memory.low, otherwise pages charged to a dead
cgroup might never get reclaimed. There's ->css_reset callback, which
would fit perfectly for the purpose. Currently, it's only called when a
subsystem is disabled in the unified hierarchy and there are other
subsystems dependant on it. Let's call it on css destruction as well.

Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

parent 63253ad8

kernel/cgroup.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -4787,6 +4787,9 @@ static void offline_css(struct cgroup_subsys_state *css)
		if (!(css->flags & CSS_ONLINE))
		return;

		if (ss->css_reset)
		ss->css_reset(css);

		if (ss->css_offline)
		ss->css_offline(css);

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