From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754813Ab1A1Et6 (ORCPT ); Thu, 27 Jan 2011 23:49:58 -0500 Received: from TYO202.gate.nec.co.jp ([202.32.8.206]:57811 "EHLO tyo202.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754684Ab1A1Et5 (ORCPT ); Thu, 27 Jan 2011 23:49:57 -0500 Date: Fri, 28 Jan 2011 13:40:19 +0900 From: Daisuke Nishimura To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "hannes@cmpxchg.org" , "balbir@linux.vnet.ibm.com" , Daisuke Nishimura Subject: Re: [BUGFIX][PATCH 1/4] memcg: fix limit estimation at reclaim for hugepage Message-Id: <20110128134019.27abcfe2.nishimura@mxp.nes.nec.co.jp> In-Reply-To: <20110128122449.e4bb0e5f.kamezawa.hiroyu@jp.fujitsu.com> References: <20110128122229.6a4c74a2.kamezawa.hiroyu@jp.fujitsu.com> <20110128122449.e4bb0e5f.kamezawa.hiroyu@jp.fujitsu.com> Organization: NEC Soft, Ltd. X-Mailer: Sylpheed 3.0.3 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 28 Jan 2011 12:24:49 +0900 KAMEZAWA Hiroyuki wrote: > From: KAMEZAWA Hiroyuki > > Current memory cgroup's code tends to assume page_size == PAGE_SIZE > and arrangement for THP is not enough yet. > > This is one of fixes for supporing THP. This adds > mem_cgroup_check_margin() and checks whether there are required amount of > free resource after memory reclaim. By this, THP page allocation > can know whether it really succeeded or not and avoid infinite-loop > and hangup. > > Total fixes for do_charge()/reclaim memory will follow this patch. > > Signed-off-by: KAMEZAWA Hiroyuki This patch looks good to me, but some nitpicks. > --- > include/linux/res_counter.h | 11 +++++++++++ > mm/memcontrol.c | 25 ++++++++++++++++++++++++- > 2 files changed, 35 insertions(+), 1 deletion(-) > > Index: mmotm-0125/include/linux/res_counter.h > =================================================================== > --- mmotm-0125.orig/include/linux/res_counter.h > +++ mmotm-0125/include/linux/res_counter.h > @@ -182,6 +182,17 @@ static inline bool res_counter_check_und > return ret; > } > > +static inline s64 res_counter_check_margin(struct res_counter *cnt) > +{ > + s64 ret; > + unsigned long flags; > + > + spin_lock_irqsave(&cnt->lock, flags); > + ret = cnt->limit - cnt->usage; > + spin_unlock_irqrestore(&cnt->lock, flags); > + return ret; > +} > + > static inline bool res_counter_check_under_soft_limit(struct res_counter *cnt) > { > bool ret; > Index: mmotm-0125/mm/memcontrol.c > =================================================================== > --- mmotm-0125.orig/mm/memcontrol.c > +++ mmotm-0125/mm/memcontrol.c > @@ -1111,6 +1111,22 @@ static bool mem_cgroup_check_under_limit > return false; > } > > +static s64 mem_cgroup_check_margin(struct mem_cgroup *mem) > +{ > + s64 mem_margin; > + > + if (do_swap_account) { > + s64 memsw_margin; > + > + mem_margin = res_counter_check_margin(&mem->res); > + memsw_margin = res_counter_check_margin(&mem->memsw); > + if (mem_margin > memsw_margin) > + mem_margin = memsw_margin; > + } else > + mem_margin = res_counter_check_margin(&mem->res); > + return mem_margin; > +} > + How about mem_margin = res_counter_check_margin(&mem->res); if (do_swap_account) memsw_margin = res_counter_check_margin(&mem->memsw); else memsw_margin = RESOURCE_MAX; return min(mem_margin, memsw_margin); ? I think using min() makes it more clear what this function does. > static unsigned int get_swappiness(struct mem_cgroup *memcg) > { > struct cgroup *cgrp = memcg->css.cgroup; > @@ -1853,7 +1869,14 @@ static int __mem_cgroup_do_charge(struct > * Check the limit again to see if the reclaim reduced the > * current usage of the cgroup before giving up > */ > - if (ret || mem_cgroup_check_under_limit(mem_over_limit)) > + if (mem_cgroup_check_margin(mem_over_limit) >= csize) > + return CHARGE_RETRY; > + > + /* > + * If the charge size is a PAGE_SIZE, it's not hopeless while > + * we can reclaim a page. > + */ > + if (csize == PAGE_SIZE && ret) > return CHARGE_RETRY; > > /* > checkpatch complains some whitespace warnings. Thanks, Daisuke Nishimura.