From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754480AbdKNJje (ORCPT ); Tue, 14 Nov 2017 04:39:34 -0500 Received: from mx2.suse.de ([195.135.220.15]:45041 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754415AbdKNJjO (ORCPT ); Tue, 14 Nov 2017 04:39:14 -0500 Date: Tue, 14 Nov 2017 10:39:09 +0100 From: Michal Hocko To: Yang Shi Cc: Jan Kara , amir73il@gmail.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] fs: fsnotify: account fsnotify metadata to kmemcg Message-ID: <20171114093909.dbhlm26qnrrb2ww4@dhcp22.suse.cz> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <10924085-6275-125f-d56b-547d734b6f4e@alibaba-inc.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. I haven't checked deeply but this doesn't look trivial to me. -- Michal Hocko SUSE Labs