On Fri, Jul 12, 2013 at 11:24:56AM +0200, Michal Hocko wrote: > Cgroup events are unregistered from the workqueue context by > cgroup_event_remove scheduled by cgroup_destroy_locked (when a cgroup is > removed by rmdir). > > cgroup_event_remove removes the eventfd wait queue from the work > queue, then it unregisters all the registered events and finally > puts a reference to the cgroup dentry. css_free which triggers memcg > deallocation is called after the last reference is dropped. > > The scheduled vmpressure work item either happens before > cgroup_event_remove or it is not triggered at all so it always happen > _before_ the last dput thus css_free. I don't follow what the above has to do with ensuring work item execution is finished before the underlying data structure is released. How are the above relevant? What am I missing here? > This patch just documents this trickiness. This doesn't have to be tricky at all. It's a *completely* routine thing. Would you please stop making it one? -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>