From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753908AbcEZMkb (ORCPT ); Thu, 26 May 2016 08:40:31 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:35669 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753842AbcEZMk3 (ORCPT ); Thu, 26 May 2016 08:40:29 -0400 From: Michal Hocko To: Cc: Tetsuo Handa , David Rientjes , Oleg Nesterov , Vladimir Davydov , Andrew Morton , LKML , 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> X-Mailer: git-send-email 2.8.1 In-Reply-To: <1464266415-15558-1-git-send-email-mhocko@kernel.org> References: <1464266415-15558-1-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). 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