From f19e8aa11afa24036c6273428da51949b5acf30c Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Wed, 22 Sep 2010 13:04:52 -0700 Subject: oom: always return a badness score of non-zero for eligible tasks 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 Cc: Dave Hansen Cc: Nitin Gupta Cc: Pekka Enberg Cc: Minchan Kim Cc: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/oom_kill.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'mm/oom_kill.c') diff --git a/mm/oom_kill.c b/mm/oom_kill.c index fc81cb22869e..859250c7dc06 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -208,8 +208,13 @@ unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem, */ 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; } -- cgit v1.2.3-59-g8ed1b