From: Michal Hocko <mhocko@xxxxxxxx> Subject: oom: warn if we go OOM for higher order and compaction is disabled Since the lumpy reclaim is gone there is no source of higher order pages if CONFIG_COMPACTION=n except for the order-0 pages reclaim which is unreliable for that purpose to say the least. Hitting an OOM for !costly higher order requests is therefore all not that hard to imagine. We are trying hard to not invoke OOM killer as much as possible but there is simply no reliable way to detect whether more reclaim retries make sense. Disabling COMPACTION is not widespread but it seems that some users might have disable the feature without realizing full consequences (mostly along with disabling THP because compaction used to be THP mainly thing). This patch just adds a note if the OOM killer was triggered by higher order request with compaction disabled. This will help us identifying possible misconfiguration right from the oom report which is easier than to always keep in mind that somebody might have disabled COMPACTION without a good reason. Link: http://lkml.kernel.org/r/20160830111632.GD23963@xxxxxxxxxxxxxx Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/oom_kill.c | 2 ++ 1 file changed, 2 insertions(+) diff -puN mm/oom_kill.c~oom-warn-if-we-go-oom-for-higher-order-and-compaction-is-disabled mm/oom_kill.c --- a/mm/oom_kill.c~oom-warn-if-we-go-oom-for-higher-order-and-compaction-is-disabled +++ a/mm/oom_kill.c @@ -406,6 +406,8 @@ static void dump_header(struct oom_contr pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), order=%d, oom_score_adj=%hd\n", current->comm, oc->gfp_mask, &oc->gfp_mask, oc->order, current->signal->oom_score_adj); + if (!IS_ENABLED(CONFIG_COMPACTION) && oc->order) + pr_warn("COMPACTION is disabled!!!\n"); cpuset_print_current_mems_allowed(); dump_stack(); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
