On Thu 23-06-11 22:01:40, Hiroyuki Kamezawa wrote: > 2011/6/23 Michal Hocko <mhocko@xxxxxxx>: > > 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. > > > > We'll have no page allocation under lock_page() held in this path. > I think it is good. But it can also cause that the page, we are about to fault in, is evicted due to allocation so we would have to do a major fault... This is probably not that serious, though. -- 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>