On Fri, Jun 14, 2013 at 02:55:39PM +0200, Michal Hocko wrote: > On Wed 12-06-13 21:04:58, Tejun Heo wrote: > [...] > > +/** > > + * cgroup_destroy_locked - the first stage of cgroup destruction > > + * @cgrp: cgroup to be destroyed > > + * > > + * css's make use of percpu refcnts whose killing latency shouldn't be > > + * exposed to userland and are RCU protected. Also, cgroup core needs to > > + * guarantee that css_tryget() won't succeed by the time ->css_offline() is > > + * invoked. To satisfy all the requirements, destruction is implemented in > > + * the following two steps. > > + * > > + * s1. Verify @cgrp can be destroyed and mark it dying. Remove all > > + * userland visible parts and start killing the percpu refcnts of > > + * css's. Set up so that the next stage will be kicked off once all > > + * the percpu refcnts are confirmed to be killed. > > + * > > + * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the > > + * rest of destruction. Once all cgroup references are gone, the > > + * cgroup is RCU-freed. > > + * > > + * This function implements s1. After this step, @cgrp is gone as far as > > + * the userland is concerned and a new cgroup with the same name may be > > + * created. As cgroup doesn't care about the names internally, this > > + * doesn't cause any problem. > > Glauber is this asumption correct for kmem caches naming scheme? > I guess it should, but I would rather be sure this won't blow up later > specially when caches might live longer than css_offline. > We append names to caches, but never the name alone, always (kmemcg_id:name) So you can reuse the same name as many times as you want (from the kmemcg perspective), provided you use different kmemcg_ids. Because kmemcg_ids are dissociated from css_ids (partly because I was already seeing people talking about wanting to free the css_ids earlier), we should not have any problems with this. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
