From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754087Ab1A1H5a (ORCPT ); Fri, 28 Jan 2011 02:57:30 -0500 Received: from zene.cmpxchg.org ([85.214.230.12]:35475 "EHLO zene.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753551Ab1A1H52 (ORCPT ); Fri, 28 Jan 2011 02:57:28 -0500 Date: Fri, 28 Jan 2011 08:57:24 +0100 From: Johannes Weiner To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "nishimura@mxp.nes.nec.co.jp" , "balbir@linux.vnet.ibm.com" Subject: Re: [BUGFIX][PATCH 2/4] memcg: fix charge path for THP and allow early retirement Message-ID: <20110128075724.GB2213@cmpxchg.org> References: <20110128122229.6a4c74a2.kamezawa.hiroyu@jp.fujitsu.com> <20110128122608.cf9be26b.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110128122608.cf9be26b.kamezawa.hiroyu@jp.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 28, 2011 at 12:26:08PM +0900, KAMEZAWA Hiroyuki wrote: > From: KAMEZAWA Hiroyuki > > When THP is used, Hugepage size charge can happen. It's not handled > correctly in mem_cgroup_do_charge(). For example, THP can fallback > to small page allocation when HUGEPAGE allocation seems difficult > or busy, but memory cgroup doesn't understand it and continue to > try HUGEPAGE charging. And the worst thing is memory cgroup > believes 'memory reclaim succeeded' if limit - usage > PAGE_SIZE. > > By this, khugepaged etc...can goes into inifinite reclaim loop > if tasks in memcg are busy. > > After this patch > - Hugepage allocation will fail if 1st trial of page reclaim fails. > > Changelog: > - make changes small. removed renaming codes. > > Signed-off-by: KAMEZAWA Hiroyuki > --- > mm/memcontrol.c | 28 ++++++++++++++++++++++++---- > 1 file changed, 24 insertions(+), 4 deletions(-) Was there something wrong with my oneline fix? Really, there is no way to make this a beautiful fix. The way this function is split up makes no sense, and the constant addition of more and more flags just to correctly communicate with _one callsite_ should be an obvious hint. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 3C4B68D0039 for ; Fri, 28 Jan 2011 02:57:28 -0500 (EST) Date: Fri, 28 Jan 2011 08:57:24 +0100 From: Johannes Weiner Subject: Re: [BUGFIX][PATCH 2/4] memcg: fix charge path for THP and allow early retirement Message-ID: <20110128075724.GB2213@cmpxchg.org> References: <20110128122229.6a4c74a2.kamezawa.hiroyu@jp.fujitsu.com> <20110128122608.cf9be26b.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110128122608.cf9be26b.kamezawa.hiroyu@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "nishimura@mxp.nes.nec.co.jp" , "balbir@linux.vnet.ibm.com" List-ID: On Fri, Jan 28, 2011 at 12:26:08PM +0900, KAMEZAWA Hiroyuki wrote: > From: KAMEZAWA Hiroyuki > > When THP is used, Hugepage size charge can happen. It's not handled > correctly in mem_cgroup_do_charge(). For example, THP can fallback > to small page allocation when HUGEPAGE allocation seems difficult > or busy, but memory cgroup doesn't understand it and continue to > try HUGEPAGE charging. And the worst thing is memory cgroup > believes 'memory reclaim succeeded' if limit - usage > PAGE_SIZE. > > By this, khugepaged etc...can goes into inifinite reclaim loop > if tasks in memcg are busy. > > After this patch > - Hugepage allocation will fail if 1st trial of page reclaim fails. > > Changelog: > - make changes small. removed renaming codes. > > Signed-off-by: KAMEZAWA Hiroyuki > --- > mm/memcontrol.c | 28 ++++++++++++++++++++++++---- > 1 file changed, 24 insertions(+), 4 deletions(-) Was there something wrong with my oneline fix? Really, there is no way to make this a beautiful fix. The way this function is split up makes no sense, and the constant addition of more and more flags just to correctly communicate with _one callsite_ should be an obvious hint. -- 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 policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org