Messages in this thread | | | Date | Tue, 19 Oct 2010 11:05:16 +0800 | From | Wu Fengguang <> | Subject | Re: Deadlock possibly caused by too_many_isolated. |
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On Tue, Oct 19, 2010 at 10:52:47AM +0800, Minchan Kim wrote: > Hi Wu, > > On Tue, Oct 19, 2010 at 11:35 AM, Wu Fengguang <fengguang.wu@intel.com> wrote: > >> @@ -2054,10 +2069,11 @@ rebalance: > >> goto got_pg; > >> > >> /* > >> - * If we failed to make any progress reclaiming, then we are > >> - * running out of options and have to consider going OOM > >> + * If we failed to make any progress reclaiming and there aren't > >> + * many parallel reclaiming, then we are unning out of options and > >> + * have to consider going OOM > >> */ > >> - if (!did_some_progress) { > >> + if (!did_some_progress && !too_many_isolated_zone(preferred_zone)) { > >> if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) { > >> if (oom_killer_disabled) > >> goto nopage; > > > > This is simply wrong. > > > > It disabled this block for 99% system because there won't be enough > > tasks to make (!too_many_isolated_zone == true). As a result the LRU > > will be scanned like mad and no task get OOMed when it should be. > > If !too_many_isolated_zone is false, it means there are already many > direct reclaiming tasks. > So they could exit reclaim path and !too_many_isolated_zone will be true. > What am I missing now?
Ah sorry, my brain get short circuited.. but I still feel uneasy with this change. It's not fixing the root cause and won't prevent too many LRU pages be isolated. It's too late to test too_many_isolated_zone() after direct reclaim returns (after sleeping for a long time).
Thanks, Fengguang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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