(2012/05/12 5:11), Glauber Costa wrote: > We call the destroy function when a cgroup starts to be removed, > such as by a rmdir event. > > However, because of our reference counters, some objects are still > inflight. Right now, we are decrementing the static_keys at destroy() > time, meaning that if we get rid of the last static_key reference, > some objects will still have charges, but the code to properly > uncharge them won't be run. > > This becomes a problem specially if it is ever enabled again, because > now new charges will be added to the staled charges making keeping > it pretty much impossible. > > We just need to be careful with the static branch activation: > since there is no particular preferred order of their activation, > we need to make sure that we only start using it after all > call sites are active. This is achieved by having a per-memcg > flag that is only updated after static_key_slow_inc() returns. > At this time, we are sure all sites are active. > > This is made per-memcg, not global, for a reason: > it also has the effect of making socket accounting more > consistent. The first memcg to be limited will trigger static_key() > activation, therefore, accounting. But all the others will then be > accounted no matter what. After this patch, only limited memcgs > will have its sockets accounted. > > [v2: changed a tcp limited flag for a generic proto limited flag ] > [v3: update the current active flag only after the static_key update ] > [v4: disarm_static_keys() inside free_work ] > [v5: got rid of tcp_limit_mutex, now in the static_key interface ] > > Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx> > CC: Tejun Heo <tj@xxxxxxxxxx> > CC: Li Zefan <lizefan@xxxxxxxxxx> > CC: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> > CC: Johannes Weiner <hannes@xxxxxxxxxxx> > CC: Michal Hocko <mhocko@xxxxxxx> Thank you for your patient works. Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> BTW, what is the relationship between 1/2 and 2/2 ? Thanks, -Kame -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>