From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id B203E828E1 for ; Thu, 26 May 2016 08:40:35 -0400 (EDT) Received: by mail-wm0-f71.google.com with SMTP id a136so45102078wme.1 for ; Thu, 26 May 2016 05:40:35 -0700 (PDT) Received: from mail-wm0-f66.google.com (mail-wm0-f66.google.com. [74.125.82.66]) by mx.google.com with ESMTPS id o11si4472688wme.27.2016.05.26.05.40.28 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 26 May 2016 05:40:28 -0700 (PDT) Received: by mail-wm0-f66.google.com with SMTP id q62so5042230wmg.3 for ; Thu, 26 May 2016 05:40:28 -0700 (PDT) From: Michal Hocko Subject: [PATCH 5/6] mm, oom: kill all tasks sharing the mm Date: Thu, 26 May 2016 14:40:14 +0200 Message-Id: <1464266415-15558-6-git-send-email-mhocko@kernel.org> In-Reply-To: <1464266415-15558-1-git-send-email-mhocko@kernel.org> References: <1464266415-15558-1-git-send-email-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Tetsuo Handa , David Rientjes , Oleg Nesterov , Vladimir Davydov , Andrew Morton , LKML , Michal Hocko From: Michal Hocko Currently oom_kill_process skips both the oom reaper and SIG_KILL if a process sharing the same mm is unkillable via OOM_ADJUST_MIN. After "mm, oom_adj: make sure processes sharing mm have same view of oom_score_adj" all such processes are sharing the same value so we shouldn't see such a task at all (oom_badness would rule them out). Moreover after "mm, oom: skip over vforked tasks" we even cannot encounter vfork task so we can allow both SIG_KILL and oom reaper. A potential race is highly unlikely but possible. It would happen if __set_oom_adj raced with select_bad_process and then it is OK to consider the old value or with fork when it should be acceptable as well. Let's add a little note to the log so that people would tell us that this really happens in the real life and it matters. Signed-off-by: Michal Hocko --- mm/oom_kill.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index d1cbaaa1a666..008c5b4732de 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -850,8 +850,7 @@ 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 (unlikely(p->flags & PF_KTHREAD) || is_global_init(p)) { /* * We cannot use oom_reaper for the mm shared by this * process because it wouldn't get killed and so the @@ -860,6 +859,11 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, can_oom_reap = false; continue; } + if (p->signal->oom_score_adj == OOM_ADJUST_MIN) + pr_warn("%s pid=%d shares mm with oom disabled %s pid=%d. Seems like misconfiguration, killing anyway!" + " Report at linux-mm@kvack.org\n", + victim->comm, task_pid_nr(victim), + p->comm, task_pid_nr(p)); do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true); } rcu_read_unlock(); -- 2.8.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org