From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754048AbcFTMoa (ORCPT ); Mon, 20 Jun 2016 08:44:30 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:33249 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753599AbcFTMoA (ORCPT ); Mon, 20 Jun 2016 08:44:00 -0400 From: Michal Hocko To: Cc: Tetsuo Handa , David Rientjes , Oleg Nesterov , Vladimir Davydov , Andrew Morton , LKML , Michal Hocko Subject: [PATCH 06/10] mm, oom: kill all tasks sharing the mm Date: Mon, 20 Jun 2016 14:43:44 +0200 Message-Id: <1466426628-15074-7-git-send-email-mhocko@kernel.org> X-Mailer: git-send-email 2.8.1 In-Reply-To: <1466426628-15074-1-git-send-email-mhocko@kernel.org> References: <1466426628-15074-1-git-send-email-mhocko@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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). We can still encounter oom disabled vforked task which has to be killed as well if we want to have other tasks sharing the mm reapable because it can access the memory before doing exec. Killing such a task should be acceptable because it is highly unlikely it has done anything useful because it cannot modify any memory before it calls exec. An alternative would be to keep the task alive and skip the oom reaper and risk all the weird corner cases where the OOM killer cannot make forward progress because the oom victim hung somewhere on the way to exit. [rientjes@google.com - drop printk when OOM_SCORE_ADJ_MIN killed task the setting is inherently racy and we cannot do much about it without introducing locks in hot paths] Acked-by: Oleg Nesterov Signed-off-by: Michal Hocko --- mm/oom_kill.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 02da660b7c25..38f89ac2df7f 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -852,8 +852,7 @@ 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 -- 2.8.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f200.google.com (mail-lb0-f200.google.com [209.85.217.200]) by kanga.kvack.org (Postfix) with ESMTP id 264276B026A for ; Mon, 20 Jun 2016 08:44:23 -0400 (EDT) Received: by mail-lb0-f200.google.com with SMTP id c1so27244577lbw.0 for ; Mon, 20 Jun 2016 05:44:23 -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 t124si9590678wmb.85.2016.06.20.05.44.04 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 20 Jun 2016 05:44:04 -0700 (PDT) Received: by mail-wm0-f66.google.com with SMTP id 187so13822392wmz.1 for ; Mon, 20 Jun 2016 05:44:04 -0700 (PDT) From: Michal Hocko Subject: [PATCH 06/10] mm, oom: kill all tasks sharing the mm Date: Mon, 20 Jun 2016 14:43:44 +0200 Message-Id: <1466426628-15074-7-git-send-email-mhocko@kernel.org> In-Reply-To: <1466426628-15074-1-git-send-email-mhocko@kernel.org> References: <1466426628-15074-1-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). We can still encounter oom disabled vforked task which has to be killed as well if we want to have other tasks sharing the mm reapable because it can access the memory before doing exec. Killing such a task should be acceptable because it is highly unlikely it has done anything useful because it cannot modify any memory before it calls exec. An alternative would be to keep the task alive and skip the oom reaper and risk all the weird corner cases where the OOM killer cannot make forward progress because the oom victim hung somewhere on the way to exit. [rientjes@google.com - drop printk when OOM_SCORE_ADJ_MIN killed task the setting is inherently racy and we cannot do much about it without introducing locks in hot paths] Acked-by: Oleg Nesterov Signed-off-by: Michal Hocko --- mm/oom_kill.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 02da660b7c25..38f89ac2df7f 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -852,8 +852,7 @@ 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 -- 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