On Thu 23-06-11 19:01:57, KAMEZAWA Hiroyuki wrote: > On Thu, 23 Jun 2011 11:02:04 +0200 > Michal Hocko <mhocko@xxxxxxx> wrote: > > > On Thu 23-06-11 17:08:11, KAMEZAWA Hiroyuki wrote: > > > On Thu, 23 Jun 2011 09:41:33 +0200 > > > Michal Hocko <mhocko@xxxxxxx> wrote: > > [...] > > > > Other than that: > > > > Reviewed-by: Michal Hocko <mhocko@xxxxxxx> > > > > > > > > > > I found the page is added to LRU before charging. (In this case, > > > memcg's LRU is ignored.) I'll post a new version with a fix. > > > > Yes, you are right. I have missed that. > > This means that we might race with reclaim which could evict the COWed > > page wich in turn would uncharge that page even though we haven't > > charged it yet. > > > > Can we postpone page_add_new_anon_rmap to the charging path or it would > > just race somewhere else? > > > > I got a different idea. How about this ? > I think this will have benefit for non-memcg users under OOM, too. Could you be more specific? I do not see how preallocation which might turn out to be pointless could help under OOM. > > A concerns is VM_FAULT_RETRY case but wait-for-lock will be much heavier > than preallocation + free-for-retry cost. Preallocation is rather costly when fault handler fails (e.g. SIGBUS which is the easiest one to trigger). I am not saying this approach is bad but I think that preallocation can be much more costly than unlock, charge and lock&recheck approach. -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- 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>