From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756185AbcE0Qsm (ORCPT ); Fri, 27 May 2016 12:48:42 -0400 Received: from mail-db3on0136.outbound.protection.outlook.com ([157.55.234.136]:37920 "EHLO emea01-db3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753676AbcE0Qsk (ORCPT ); Fri, 27 May 2016 12:48:40 -0400 Authentication-Results: kernel.org; dkim=none (message not signed) header.d=none;kernel.org; dmarc=none action=none header.from=virtuozzo.com; Date: Fri, 27 May 2016 19:48:30 +0300 From: Vladimir Davydov To: Michal Hocko CC: , Tetsuo Handa , David Rientjes , Oleg Nesterov , Andrew Morton , LKML , Michal Hocko Subject: Re: [PATCH 4/6] mm, oom: skip over vforked tasks Message-ID: <20160527164830.GF26059@esperanza> References: <1464266415-15558-1-git-send-email-mhocko@kernel.org> <1464266415-15558-5-git-send-email-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; 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X-Microsoft-Exchange-Diagnostics: 1;AM3PR08MB0579;23: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 X-Microsoft-Exchange-Diagnostics: 1;AM3PR08MB0579;5:9HDz7g7wBLrx3HiCmnXdGiC4seuXSCDYa1lzpubkXMmzi1NKJPcRWe/jmtLAVLAdX3tYicJGe6SzNMzXAE5MZ6M+EF2ZsLIP6PKyAN+9ZEdgNVG/pnyoIC9R8QrfYV+AjdQV124bY3vsqOO8Ft9ZIw==;24:SP5AH5VFaJAUmdWey3jKNgGfRydzQdll2KoCHwyFfRxr4qVQ4+KTodYvTZkSuTMb0Roix1KlWiCyZFS/qET8STw2P1I2Jy63HQ1yYWTv1Do=;7:NAHlVHK2dcquqM/O7Jf5VwTuiL3XvUgieYFC+M0EbgCESQFqsyfp1fXUGcejixhboFwKGd0PE+fz/LwbGOoOe34XOF2RyRIvYNpfAGHXv15DQCSJ5vbQD/Q/5R1sKGE2CRS6eVrN2GMykArAzcjmayX7q+kyEG7OTe+e/LCbOHC1FmNdom+MGVZjJMHRXS79;20:17vSxZPiYHXRTD7xdpOPiXJduUx+/nJS8HkCMtawTkM2l7hvTm7MUi5q1hEikRBHbhC1JrHKzYRTYadeLT9Nxd+1c909wIgy2SA6NnIHx4wd6EgTrEZrVu9hXQHxVB6OJ7Gy8el44VmXf8UOZS8cvYHmpEay0umLPyJgw58CqtY= SpamDiagnosticOutput: 1:23 SpamDiagnosticMetadata: NSPM X-OriginatorOrg: virtuozzo.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 May 2016 16:48:34.8675 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM3PR08MB0579 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 26, 2016 at 02:40:13PM +0200, Michal Hocko wrote: > From: Michal Hocko > > vforked tasks are not really sitting on memory so it doesn't matter much > to kill them. Parents are waiting for vforked task killable so it is > better to chose parent which is the real mm owner. Teach oom_badness > to ignore all tasks which haven't passed mm_release. oom_kill_process > should ignore them as well because they will drop the mm soon and they > will not block oom_reaper because they cannot touch any memory. That is, if a process calls vfork->exec to spawn a child, and a newly spawned child happens to invoke oom somewhere in exec, instead of killing the child, which hasn't done anything yet, we'll kill the main process while the child continues to run. Not sure if it's really bad though. ... > @@ -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. > + */ > + if (p->vfork_done) > + continue; > if (same_thread_group(p, victim)) > continue; > if (unlikely(p->flags & PF_KTHREAD) || is_global_init(p) ||