From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qe0-f51.google.com (mail-qe0-f51.google.com [209.85.128.51]) by kanga.kvack.org (Postfix) with ESMTP id 436BD6B005A for ; Wed, 4 Dec 2013 21:50:32 -0500 (EST) Received: by mail-qe0-f51.google.com with SMTP id 1so14620831qee.24 for ; Wed, 04 Dec 2013 18:50:32 -0800 (PST) Received: from mail-qc0-x234.google.com (mail-qc0-x234.google.com [2607:f8b0:400d:c01::234]) by mx.google.com with ESMTPS id dh4si17186920qcb.54.2013.12.04.18.50.31 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 04 Dec 2013 18:50:31 -0800 (PST) Received: by mail-qc0-f180.google.com with SMTP id w7so4276860qcr.25 for ; Wed, 04 Dec 2013 18:50:31 -0800 (PST) Date: Wed, 4 Dec 2013 21:50:26 -0500 From: Tejun Heo Subject: Re: [patch 7/8] mm, memcg: allow processes handling oom notifications to access reserves Message-ID: <20131205025026.GA26777@htj.dyndns.org> References: <20131119134007.GD20655@dhcp22.suse.cz> <20131120152251.GA18809@dhcp22.suse.cz> <20131128115458.GK2761@dhcp22.suse.cz> <20131204054533.GZ3556@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Johannes Weiner , Andrew Morton , Michal Hocko , KAMEZAWA Hiroyuki , Mel Gorman , Rik van Riel , Pekka Enberg , Christoph Lameter , Li Zefan , linux-kernel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org Hello, On Wed, Dec 04, 2013 at 05:49:04PM -0800, David Rientjes wrote: > That's not what this series is addressing, though, and in fact it's quite > the opposite. It acknowledges that userspace oom handlers need to > allocate and that anything else would be too difficult to maintain > (thereby agreeing with the above), so we must set aside memory that they > are exclusively allowed to access. For the vast majority of users who > will not use userspace oom handlers, they can just use the default value > of memory.oom_reserve_in_bytes == 0 and they incur absolutely no side- > effects as a result of this series. Umm.. without delving into details, aren't you basically creating a memory cgroup inside a memory cgroup? Doesn't sound like a particularly well thought-out plan to me. > For those who do use userspace oom handlers, like Google, this allows us > to set aside memory to allow the userspace oom handlers to kill a process, > dump the heap, send a signal, drop caches, etc. when waking up. Seems kinda obvious. Put it in a separate cgroup? You're basically saying it doesn't want to be under the same memory limit as the processes that it's looking over. That's like the definition of being in a different cgroup. Thanks. -- tejun -- 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