The patch titled
Subject: oom: warn if we go OOM for higher order and compaction is disabled
has been added to the -mm tree. Its filename is
oom-warn-if-we-go-oom-for-higher-order-and-compaction-is-disabled.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/oom-warn-if-we-go-oom-for-higher-order-and-compaction-is-disabled.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/oom-warn-if-we-go-oom-for-higher-order-and-compaction-is-disabled.patch
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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();
_
Patches currently in -mm which might be from mhocko@xxxxxxxx are
mm-oom-prevent-pre-mature-oom-killer-invocation-for-high-order-request.patch
mm-vmscan-get-rid-of-throttle_vm_writeout.patch
oom-keep-mm-of-the-killed-task-available.patch
kernel-oom-fix-potential-pgd_lock-deadlock-from-__mmdrop.patch
mm-oom-get-rid-of-signal_struct-oom_victims.patch
oom-suspend-fix-oom_killer_disable-vs-pm-suspend-properly.patch
mm-make-sure-that-kthreads-will-not-refault-oom-reaped-memory.patch
oom-oom_reaper-allow-to-reap-mm-shared-by-the-kthreads.patch
oom-warn-if-we-go-oom-for-higher-order-and-compaction-is-disabled.patch
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