From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx174.postini.com [74.125.245.174]) by kanga.kvack.org (Postfix) with SMTP id 46C586B004F for ; Thu, 19 Jan 2012 15:07:25 -0500 (EST) Received: by qcsf14 with SMTP id f14so219036qcs.14 for ; Thu, 19 Jan 2012 12:07:24 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20120118130102.GC31112@tiehlicka.suse.cz> References: <20120113173001.ee5260ca.kamezawa.hiroyu@jp.fujitsu.com> <20120113173227.df2baae3.kamezawa.hiroyu@jp.fujitsu.com> <20120117151619.GA21348@tiehlicka.suse.cz> <20120118085558.6ed1a988.kamezawa.hiroyu@jp.fujitsu.com> <20120118130102.GC31112@tiehlicka.suse.cz> Date: Thu, 19 Jan 2012 12:07:22 -0800 Message-ID: Subject: Re: [RFC] [PATCH 1/7 v2] memcg: remove unnecessary check in mem_cgroup_update_page_stat() From: Ying Han Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: KAMEZAWA Hiroyuki , "linux-mm@kvack.org" , "hugh.dickins@tiscali.co.uk" , "hannes@cmpxchg.org" , cgroups@vger.kernel.org, "bsingharora@gmail.com" On Wed, Jan 18, 2012 at 5:01 AM, Michal Hocko wrote: > On Wed 18-01-12 08:55:58, KAMEZAWA Hiroyuki wrote: >> On Tue, 17 Jan 2012 16:16:20 +0100 >> Michal Hocko wrote: >> >> > On Fri 13-01-12 17:32:27, KAMEZAWA Hiroyuki wrote: >> > > >> > > From 788aebf15f3fa37940e0745cab72547e20683bf2 Mon Sep 17 00:00:00 20= 01 >> > > From: KAMEZAWA Hiroyuki >> > > Date: Thu, 12 Jan 2012 16:08:33 +0900 >> > > Subject: [PATCH 1/7] memcg: remove unnecessary check in mem_cgroup_u= pdate_page_stat() >> > > >> > > commit 10ea69f1182b removes move_lock_page_cgroup() in thp-split pat= h. >> > > So, this PageTransHuge() check is unnecessary, too. >> > >> > I do not see commit like that in the tree. I guess you meant >> > memcg: make mem_cgroup_split_huge_fixup() more efficient which is not >> > merged yet, right? >> > >> >> This commit in the linux-next. > > Referring to commits from linux-next is tricky as it changes all the > time. I guess that the full commit subject should be sufficient. > >> > > Note: >> > > =A0- considering when mem_cgroup_update_page_stat() is called, >> > > =A0 =A0there will be no race between split_huge_page() and update_pa= ge_stat(). >> > > =A0 =A0All required locks are held in higher level. >> > >> > We should never have THP page in this path in the first place. So why >> > not changing this to VM_BUG_ON(PageTransHuge). >> > >> >> Ying Han considers to support mlock stat. > > OK, got it. What about the following updated changelog instead? > > =3D=3D=3D > We do not have to check PageTransHuge in mem_cgroup_update_page_stat > and fallback into the locked accounting because both move charge and thp one nitpick. Should it be "move account" instead of "move charge"? --Ying > split up are done with compound_lock so they cannot race. update vs. > move is protected by the mem_cgroup_stealed sufficiently. > > PageTransHuge pages shouldn't appear in this code path currently because > we are tracking only file pages at the moment but later we are planning > to track also other pages (e.g. mlocked ones). > =3D=3D=3D > >> >> Thanks, >> -Kame >> >> -- >> To unsubscribe from this list: send the line "unsubscribe cgroups" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at =A0http://vger.kernel.org/majordomo-info.html > > -- > Michal Hocko > SUSE Labs > SUSE LINUX s.r.o. > Lihovarska 1060/12 > 190 00 Praha 9 > Czech Republic -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org