The patch titled
oom: always return a badness score of non-zero for eligible tasks
has been added to the -mm tree. Its filename is
oom-always-return-a-badness-score-of-non-zero-for-eligible-tasks.patch
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Subject: oom: always return a badness score of non-zero for eligible tasks
From: David Rientjes <rientjes@xxxxxxxxxx>
A task's badness score is roughly a proportion of its rss and swap
compared to the system's capacity. The scale ranges from 0 to 1000 with
the highest score chosen for kill. Thus, this scale operates on a
resolution of 0.1% of RAM + swap. Admin tasks are also given a 3% bonus,
so the badness score of an admin task using 3% of memory, for example,
would still be 0.
It's possible that an exceptionally large number of tasks will combine to
exhaust all resources but never have a single task that uses more than
0.1% of RAM and swap (or 3.0% for admin tasks).
This patch ensures that the badness score of any eligible task is never 0
so the machine doesn't unnecessarily panic because it cannot find a task
to kill.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/oom_kill.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff -puN mm/oom_kill.c~oom-always-return-a-badness-score-of-non-zero-for-eligible-tasks mm/oom_kill.c
--- a/mm/oom_kill.c~oom-always-return-a-badness-score-of-non-zero-for-eligible-tasks
+++ a/mm/oom_kill.c
@@ -208,8 +208,13 @@ unsigned int oom_badness(struct task_str
*/
points += p->signal->oom_score_adj;
- if (points < 0)
- return 0;
+ /*
+ * Never return 0 for an eligible task that may be killed since it's
+ * possible that no single user task uses more than 0.1% of memory and
+ * no single admin tasks uses more than 3.0%.
+ */
+ if (points <= 0)
+ return 1;
return (points < 1000) ? points : 1000;
}
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
origin.patch
oom-always-return-a-badness-score-of-non-zero-for-eligible-tasks.patch
linux-next.patch
oom-add-per-mm-oom-disable-count.patch
oom-avoid-killing-a-task-if-a-thread-sharing-its-mm-cannot-be-killed.patch
oom-kill-all-threads-sharing-oom-killed-tasks-mm.patch
oom-kill-all-threads-sharing-oom-killed-tasks-mm-fix.patch
oom-kill-all-threads-sharing-oom-killed-tasks-mm-fix-fix.patch
oom-rewrite-error-handling-for-oom_adj-and-oom_score_adj-tunables.patch
oom-fix-locking-for-oom_adj-and-oom_score_adj.patch
mm-mempolicy-check-return-code-of-check_range.patch
jbd-remove-dependency-on-__gfp_nofail.patch
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