linux-kernel - Re: [PATCH v2] mm,oom: exclude oom_task_origin processes if they are OOM-unkillable.

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Date:	Sat, 20 Feb 2016 00:07:05 +0900
From:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:	mhocko@...nel.org
Cc:	rientjes@...gle.com, akpm@...ux-foundation.org, mgorman@...e.de,
	oleg@...hat.com, torvalds@...ux-foundation.org, hughd@...gle.com,
	andrea@...nel.org, riel@...hat.com, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mm,oom: exclude oom_task_origin processes if they are OOM-unkillable.

Michal Hocko wrote:
> On Thu 18-02-16 13:08:49, Michal Hocko wrote:
> > I guess we can safely remove the memcg
> > argument from oom_badness and oom_unkillable_task. At least from a quick
> > glance...
> 
> No we cannot actually. oom_kill_process could select a child which is in
> a different memcg in that case...

Then, don't we need to check whether processes sharing victim->mm in other
thread groups are in the same memcg when we walk the process list?

----------
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index f426ce8..d05db31 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -762,8 +762,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
 			continue;
 		if (same_thread_group(p, victim))
 			continue;
-		if (unlikely(p->flags & PF_KTHREAD) || is_global_init(p) ||
-		    p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {
+		if (oom_badness(p, memcg, oc, totalpages, false) == 0) {
 			/*
 			 * We cannot use oom_reaper for the mm shared by this
 			 * process because it wouldn't get killed and so the
----------