(2013/03/06 17:38), Glauber Costa wrote: > >> >>> Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx> >>> CC: Michal Hocko <mhocko@xxxxxxx> >>> CC: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> >>> CC: Johannes Weiner <hannes@xxxxxxxxxxx> >>> CC: Mel Gorman <mgorman@xxxxxxx> >>> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> >> >> After quick look, it seems most parts are good. But I have a concern. >> >> At memcg enablement, you move the numbers from vm_stat[] to res_counters. >> > Not only to res_counters. Mostly to mem_cgroup_stat_cpu, but I do move > to res_counters as well. > >> Why you need it ? It's not explained. > > Because at this point, the bypass will no longer be in effect and we > need accurate figures in root cgroup about what happened so far. > > If we always have root-level hierarchy, then the bypass could go on > forever. But if we have not, we'll need to rely on whatever was in there. > >> And if it's necessary, uncharge will leak because page_cgroup is not marked >> as PCG_USED, pc->mem_cgroup == NULL. So, res.usage will not be decreased. >> > > The same problem happen when deriving an mz from a page. Since > pc->mem_cgroup will be NULL. I am interpreting that as "root mem cgroup". > yes. > Maybe even better would be to scan page cgroup writing a magic. Then if > we see that magic we are sure it is an uninitialized pc. > >> Could you fix it if you need to move numbers to res_counter ? >> > > At least for the pages in LRUs, I can scan them all, and update their > page information. I am just wondering if this isn't a *very* expensive > operation. Fine that we do it once, but still, is potentially scanning > *all* pages in the system. > > So I've basically decided it is better to interpret pc->mem_cgroup = > NULL as this uninitialized state. (and can change to a magic) > I think it can work. 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>