On 05/14/2012 04:59 AM, KAMEZAWA Hiroyuki wrote: > (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 ? Can't do jump label patching inside an interrupt handler. They need to happen when we free the structure, and I was about to add a worker myself when I found out we already have one: just we don't always use it. Before we merge it, let me just make sure the issue with config Li pointed out don't exist. I did test it, but since I've reposted this many times with multiple tiny changes - the type that will usually get us killed, I'd be more comfortable with an extra round of testing if someone spotted a possibility. Who is merging this fix, btw ? I find it to be entirely memcg related, even though it touches a file in net (but a file with only memcg code in it) -- 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>