On Thu 11-10-12 18:36:26, KOSAKI Motohiro wrote: > On Thu, Oct 11, 2012 at 4:57 AM, Michal Hocko <[email protected]> wrote: > > oom_badness takes totalpages argument which says how many pages are > > available and it uses it as a base for the score calculation. The value > > is calculated by mem_cgroup_get_limit which considers both limit and > > total_swap_pages (resp. memsw portion of it). > > > > This is usually correct but since fe35004f (mm: avoid swapping out > > with swappiness==0) we do not swap when swappiness is 0 which means > > that we cannot really use up all the totalpages pages. This in turn > > confuses oom score calculation if the memcg limit is much smaller than > > the available swap because the used memory (capped by the limit) is > > negligible comparing to totalpages so the resulting score is too small > > if adj!=0 (typically task with CAP_SYS_ADMIN or non zero oom_score_adj). > > A wrong process might be selected as result. > > > > The same issue exists for the global oom killer as well but it is not > > that problematic as the amount of the RAM is usually much bigger than > > the swap space. > > > > The problem can be worked around by checking mem_cgroup_swappiness==0 > > and not considering swap at all in such a case. > > > > Signed-off-by: Michal Hocko <[email protected]> > > Acked-by: David Rientjes <[email protected]> > > Cc: stable [3.5+] > > Acked-by: KOSAKI Motohiro <[email protected]>
Thanks! -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
