From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f51.google.com (mail-pa0-f51.google.com [209.85.220.51]) by kanga.kvack.org (Postfix) with ESMTP id 8E0F46B0005 for ; Mon, 29 Feb 2016 12:02:19 -0500 (EST) Received: by mail-pa0-f51.google.com with SMTP id fl4so94996296pad.0 for ; Mon, 29 Feb 2016 09:02:19 -0800 (PST) Received: from mx2.parallels.com (mx2.parallels.com. [199.115.105.18]) by mx.google.com with ESMTPS id fl1si5330240pab.55.2016.02.29.09.02.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 29 Feb 2016 09:02:18 -0800 (PST) From: Vladimir Davydov Subject: [PATCH] exit: clear TIF_MEMDIE after exit_task_work Date: Mon, 29 Feb 2016 20:02:09 +0300 Message-ID: <1456765329-14890-1-git-send-email-vdavydov@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Michal Hocko , Tetsuo Handa , David Rientjes , linux-mm@kvack.org, linux-kernel@vger.kernel.org An mm_struct may be pinned by a file. An example is vhost-net device created by a qemu/kvm (see vhost_net_ioctl -> vhost_net_set_owner -> vhost_dev_set_owner). If such process gets OOM-killed, the reference to its mm_struct will only be released from exit_task_work -> ____fput -> __fput -> vhost_net_release -> vhost_dev_cleanup, which is called after exit_mmap, where TIF_MEMDIE is cleared. As a result, we can start selecting the next victim before giving the last one a chance to free its memory. In practice, this leads to killing several VMs along with the fattest one. Signed-off-by: Vladimir Davydov --- kernel/exit.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index fd90195667e1..cc50e12165f7 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -434,8 +434,6 @@ static void exit_mm(struct task_struct *tsk) task_unlock(tsk); mm_update_next_owner(mm); mmput(mm); - if (test_thread_flag(TIF_MEMDIE)) - exit_oom_victim(tsk); } static struct task_struct *find_alive_thread(struct task_struct *p) @@ -746,6 +744,8 @@ void do_exit(long code) disassociate_ctty(1); exit_task_namespaces(tsk); exit_task_work(tsk); + if (test_thread_flag(TIF_MEMDIE)) + exit_oom_victim(tsk); exit_thread(); /* -- 2.1.4 -- 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