From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755300AbdKNRck (ORCPT ); Tue, 14 Nov 2017 12:32:40 -0500 Received: from out0-231.mail.aliyun.com ([140.205.0.231]:47315 "EHLO out0-231.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752151AbdKNRcc (ORCPT ); Tue, 14 Nov 2017 12:32:32 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R911e4;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e02c03297;MF=yang.s@alibaba-inc.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---.9POAS0q_1510680739; Subject: Re: [PATCH v2] fs: fsnotify: account fsnotify metadata to kmemcg To: Michal Hocko Cc: Jan Kara , amir73il@gmail.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1509128538-50162-1-git-send-email-yang.s@alibaba-inc.com> <20171030124358.GF23278@quack2.suse.cz> <76a4d544-833a-5f42-a898-115640b6783b@alibaba-inc.com> <20171031101238.GD8989@quack2.suse.cz> <20171109135444.znaksm4fucmpuylf@dhcp22.suse.cz> <10924085-6275-125f-d56b-547d734b6f4e@alibaba-inc.com> <20171114093909.dbhlm26qnrrb2ww4@dhcp22.suse.cz> From: "Yang Shi" Message-ID: Date: Wed, 15 Nov 2017 01:32:16 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20171114093909.dbhlm26qnrrb2ww4@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/14/17 1:39 AM, Michal Hocko wrote: > On Tue 14-11-17 03:10:22, Yang Shi wrote: >> >> >> On 11/9/17 5:54 AM, Michal Hocko wrote: >>> [Sorry for the late reply] >>> >>> On Tue 31-10-17 11:12:38, Jan Kara wrote: >>>> On Tue 31-10-17 00:39:58, Yang Shi wrote: >>> [...] >>>>> I do agree it is not fair and not neat to account to producer rather than >>>>> misbehaving consumer, but current memcg design looks not support such use >>>>> case. And, the other question is do we know who is the listener if it >>>>> doesn't read the events? >>>> >>>> So you never know who will read from the notification file descriptor but >>>> you can simply account that to the process that created the notification >>>> group and that is IMO the right process to account to. >>> >>> Yes, if the creator is de-facto owner which defines the lifetime of >>> those objects then this should be a target of the charge. >>> >>>> I agree that current SLAB memcg accounting does not allow to account to a >>>> different memcg than the one of the running process. However I *think* it >>>> should be possible to add such interface. Michal? >>> >>> We do have memcg_kmem_charge_memcg but that would require some plumbing >>> to hook it into the specific allocation path. I suspect it uses kmalloc, >>> right? >> >> Yes. >> >> I took a look at the implementation and the callsites of >> memcg_kmem_charge_memcg(). It looks it is called by: >> >> * charge kmem to memcg, but it is charged to the allocator's memcg >> * allocate new slab page, charge to memcg_params.memcg >> >> I think this is the plumbing you mentioned, right? > > Maybe I have misunderstood, but you are using slab allocator. So you > would need to force it to use a different charging context than current. Yes. > I haven't checked deeply but this doesn't look trivial to me. I agree. This is also what I explained to Jan and Amir in earlier discussion. Yang >