From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933678AbbCDRlc (ORCPT ); Wed, 4 Mar 2015 12:41:32 -0500 Received: from gum.cmpxchg.org ([85.214.110.215]:48948 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932828AbbCDRla (ORCPT ); Wed, 4 Mar 2015 12:41:30 -0500 Date: Wed, 4 Mar 2015 12:40:56 -0500 From: Johannes Weiner To: Michal Hocko Cc: Chen Gang <762976180@qq.com>, cgroups@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] mm: memcontrol: Let mem_cgroup_move_account() have effect only if MMU enabled Message-ID: <20150304174056.GA20376@phnom.home.cmpxchg.org> References: <54F4E739.6040805@qq.com> <20150303134524.GE2409@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150303134524.GE2409@dhcp22.suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 03, 2015 at 02:45:24PM +0100, Michal Hocko wrote: > On Tue 03-03-15 06:42:01, Chen Gang wrote: > > When !MMU, it will report warning. The related warning with allmodconfig > > under c6x: > > Does it even make any sense to enable CONFIG_MEMCG when !CONFIG_MMU? > Is anybody using this configuration and is it actually usable? My > knowledge about CONFIG_MMU is close to zero so I might be missing > something but I do not see a point into fixing compile warnings when > the whole subsystem is not usable in the first place. It's very limited, and anonymous memory is not even charged right now, even though it could be -- see nommu.c::do_mmap_private(). But there is nothing inherent in the memcg functionality that would require an MMU I guess, except for these ridiculous charge moving pte walkers. > > Signed-off-by: Chen Gang Acked-by: Johannes Weiner