From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756236Ab2GJQWy (ORCPT ); Tue, 10 Jul 2012 12:22:54 -0400 Received: from cantor2.suse.de ([195.135.220.15]:50406 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753423Ab2GJQWw (ORCPT ); Tue, 10 Jul 2012 12:22:52 -0400 Date: Tue, 10 Jul 2012 18:22:50 +0200 From: Michal Hocko To: Wanpeng Li Cc: Johannes Weiner , Andrew Morton , KAMEZAWA Hiroyuki , Hugh Dickins , David Rientjes , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [patch 08/11] mm: memcg: remove needless !mm fixup to init_mm when charging Message-ID: <20120710162249.GA29114@tiehlicka.suse.cz> References: <1341449103-1986-1-git-send-email-hannes@cmpxchg.org> <1341449103-1986-9-git-send-email-hannes@cmpxchg.org> <20120709152058.GK4627@tiehlicka.suse.cz> <20120710061021.GA6096@kernel> <20120710062104.GA19223@tiehlicka.suse.cz> <20120710065448.GB6096@kernel> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120710065448.GB6096@kernel> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 10-07-12 14:54:48, Wanpeng Li wrote: > On Tue, Jul 10, 2012 at 08:21:04AM +0200, Michal Hocko wrote: > >On Tue 10-07-12 14:10:21, Wanpeng Li wrote: > >> On Mon, Jul 09, 2012 at 05:20:58PM +0200, Michal Hocko wrote: > >> >On Thu 05-07-12 02:45:00, Johannes Weiner wrote: > >> >> It does not matter to __mem_cgroup_try_charge() if the passed mm is > >> >> NULL or init_mm, it will charge the root memcg in either case. > >> > >> You can also change the comment in __mem_cgroup_try_charge : > >> > >> "if so charge the init_mm" => "if so charge the root memcg" > > > >This is already in place: > >" > >If mm is NULL and the caller doesn't pass a valid memcg pointer, that is > >treated as a charge to root_mem_cgroup. > >" > > IIUC, if still keep comment "if so charge the init_mm" is not correct, > since pages in pagecache aren't mapped into any processes' ptes, > so mm is NULL, and these pages which in pagecache are not belong > to init_mm, the comment should be changed. :-) Fair enough. I guess Johannes will change that in the next post. -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic