From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754223AbcE3HOB (ORCPT ); Mon, 30 May 2016 03:14:01 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:36492 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751151AbcE3HN7 (ORCPT ); Mon, 30 May 2016 03:13:59 -0400 Date: Mon, 30 May 2016 09:13:57 +0200 From: Michal Hocko To: Vladimir Davydov Cc: linux-mm@kvack.org, Tetsuo Handa , David Rientjes , Oleg Nesterov , Andrew Morton , LKML Subject: Re: [PATCH 4/6] mm, oom: skip over vforked tasks Message-ID: <20160530071357.GE22928@dhcp22.suse.cz> References: <1464266415-15558-1-git-send-email-mhocko@kernel.org> <1464266415-15558-5-git-send-email-mhocko@kernel.org> <20160527164830.GF26059@esperanza> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160527164830.GF26059@esperanza> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 27-05-16 19:48:30, Vladimir Davydov wrote: > On Thu, May 26, 2016 at 02:40:13PM +0200, Michal Hocko wrote: [...] > > @@ -839,6 +841,13 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, > > for_each_process(p) { > > if (!process_shares_mm(p, mm)) > > continue; > > + /* > > + * vforked tasks are ignored because they will drop the mm soon > > + * hopefully and even if not they will not mind being oom > > + * reaped because they cannot touch any memory. > > They shouldn't modify memory, but they still can touch it AFAIK. You are right. This means that the vforked child might see zero pages. Let me think whether this is acceptable or not. Thanks! > > > + */ > > + if (p->vfork_done) > > + continue; > > if (same_thread_group(p, victim)) > > continue; > > if (unlikely(p->flags & PF_KTHREAD) || is_global_init(p) || -- Michal Hocko SUSE Labs