From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 735B26B0044 for ; Thu, 8 Jan 2009 20:09:37 -0500 (EST) Received: from m6.gw.fujitsu.co.jp ([10.0.50.76]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n0919YoV016863 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Fri, 9 Jan 2009 10:09:34 +0900 Received: from smail (m6 [127.0.0.1]) by outgoing.m6.gw.fujitsu.co.jp (Postfix) with ESMTP id AD6CD45DE5C for ; Fri, 9 Jan 2009 10:09:33 +0900 (JST) Received: from s6.gw.fujitsu.co.jp (s6.gw.fujitsu.co.jp [10.0.50.96]) by m6.gw.fujitsu.co.jp (Postfix) with ESMTP id 7C36C45DE55 for ; Fri, 9 Jan 2009 10:09:33 +0900 (JST) Received: from s6.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s6.gw.fujitsu.co.jp (Postfix) with ESMTP id 058811DB803B for ; Fri, 9 Jan 2009 10:09:33 +0900 (JST) Received: from m108.s.css.fujitsu.com (m108.s.css.fujitsu.com [10.249.87.108]) by s6.gw.fujitsu.co.jp (Postfix) with ESMTP id 7D7961DB803F for ; Fri, 9 Jan 2009 10:09:32 +0900 (JST) Date: Fri, 9 Jan 2009 10:08:30 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [RFC][PATCH 3/4] memcg: fix for mem_cgroup_hierarchical_reclaim Message-Id: <20090109100830.3e9c90e0.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <39822.10.75.179.62.1231412881.squirrel@webmail-b.css.fujitsu.com> References: <20090108190818.b663ce20.nishimura@mxp.nes.nec.co.jp> <20090108191501.dc469a51.nishimura@mxp.nes.nec.co.jp> <39822.10.75.179.62.1231412881.squirrel@webmail-b.css.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Daisuke Nishimura , linux-mm@kvack.org, linux-kernel@vger.kernel.org, balbir@linux.vnet.ibm.com, lizf@cn.fujitsu.com, menage@google.com List-ID: On Thu, 8 Jan 2009 20:08:01 +0900 (JST) "KAMEZAWA Hiroyuki" wrote: > Daisuke Nishimura said: > > If root_mem has no children, last_scaned_child is set to root_mem itself. > > But after some children added to root_mem, mem_cgroup_get_next_node can > > mem_cgroup_put the root_mem although root_mem has not been mem_cgroup_get. > > > > This patch fixes this behavior by: > > - Set last_scanned_child to NULL if root_mem has no children or DFS search > > has returned to root_mem itself(root_mem is not a "child" of root_mem). > > Make mem_cgroup_get_first_node return root_mem in this case. > > There are no mem_cgroup_get/put for root_mem. > > - Rename mem_cgroup_get_next_node to __mem_cgroup_get_next_node, and > > mem_cgroup_get_first_node to mem_cgroup_get_next_node. > > Make mem_cgroup_hierarchical_reclaim call only new > > mem_cgroup_get_next_node. > > > > > > Signed-off-by: Daisuke Nishimura > > Hmm, seems necessary fix. Then, it's better to rebase my patch on to this. > > Reviewed-by: KAMEZAWA Hiroyuki > > Maybe simpler one can be written but my patch remove all this out later.... > How about this ? (just an exmaple and not tested, sorry) --- mm/memcontrol.c | 52 ++++++++++++++++++++++------------------------------ 1 file changed, 22 insertions(+), 30 deletions(-) Index: mmotm-2.6.28-Jan7/mm/memcontrol.c =================================================================== --- mmotm-2.6.28-Jan7.orig/mm/memcontrol.c +++ mmotm-2.6.28-Jan7/mm/memcontrol.c @@ -621,6 +621,7 @@ static struct mem_cgroup * mem_cgroup_get_next_node(struct mem_cgroup *curr, struct mem_cgroup *root_mem) { struct cgroup *cgroup, *curr_cgroup, *root_cgroup; + struct mem_cgroup *orig = root_mem->last_scanned_child; curr_cgroup = curr->css.cgroup; root_cgroup = root_mem->css.cgroup; @@ -629,19 +630,15 @@ mem_cgroup_get_next_node(struct mem_cgro /* * Walk down to children */ - mem_cgroup_put(curr); cgroup = list_entry(curr_cgroup->children.next, struct cgroup, sibling); curr = mem_cgroup_from_cont(cgroup); - mem_cgroup_get(curr); goto done; } visit_parent: if (curr_cgroup == root_cgroup) { - mem_cgroup_put(curr); curr = root_mem; - mem_cgroup_get(curr); goto done; } @@ -649,11 +646,9 @@ visit_parent: * Goto next sibling */ if (curr_cgroup->sibling.next != &curr_cgroup->parent->children) { - mem_cgroup_put(curr); cgroup = list_entry(curr_cgroup->sibling.next, struct cgroup, sibling); curr = mem_cgroup_from_cont(cgroup); - mem_cgroup_get(curr); goto done; } @@ -664,7 +659,10 @@ visit_parent: goto visit_parent; done: + if (orig) + mem_cgroup_put(orig); root_mem->last_scanned_child = curr; + mem_cgroup_get(curr); return curr; } @@ -677,35 +675,25 @@ static struct mem_cgroup * mem_cgroup_get_first_node(struct mem_cgroup *root_mem) { struct cgroup *cgroup; - struct mem_cgroup *ret; - bool obsolete; + struct mem_cgroup *ret, *orig; - obsolete = mem_cgroup_is_obsolete(root_mem->last_scanned_child); - - /* - * Scan all children under the mem_cgroup mem - */ mutex_lock(&mem_cgroup_subsys.hierarchy_mutex); - if (list_empty(&root_mem->css.cgroup->children)) { - ret = root_mem; - goto done; - } - - if (!root_mem->last_scanned_child || obsolete) { - - if (obsolete && root_mem->last_scanned_child) - mem_cgroup_put(root_mem->last_scanned_child); + orig = root_mem->last_scanned_child; - cgroup = list_first_entry(&root_mem->css.cgroup->children, - struct cgroup, sibling); - ret = mem_cgroup_from_cont(cgroup); + if (!orig) { + if (list_empty(&root_mem->css.cgroup->children)) { + ret = root_mem; + } else { + cgroup = + list_first_entry(&root_mem->css.cgroup->children, + struct cgroup, sibling); + ret = mem_cgroup_from_cont(cgroup); + } + root_mem->last_scanned_child = ret; mem_cgroup_get(ret); - } else + } else /* get_next_node will manage refcnt */ ret = mem_cgroup_get_next_node(root_mem->last_scanned_child, root_mem); - -done: - root_mem->last_scanned_child = ret; mutex_unlock(&mem_cgroup_subsys.hierarchy_mutex); return ret; } @@ -2232,7 +2220,11 @@ static void mem_cgroup_pre_destroy(struc static void mem_cgroup_destroy(struct cgroup_subsys *ss, struct cgroup *cont) { - mem_cgroup_put(mem_cgroup_from_cont(cont)); + struct mem_cgroup *mem = mem_cgroup_from_cont(cont); + + if (mem->last_scanned_child == mem) + mem_cgroup_put(mem); + mem_cgroup_put(mem); } static int mem_cgroup_populate(struct cgroup_subsys *ss, -- 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/ . Don't email: email@kvack.org