From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id E03EA9000C4 for ; Mon, 26 Sep 2011 18:50:25 -0400 (EDT) Message-ID: <4E810187.3000106@parallels.com> Date: Mon, 26 Sep 2011 19:49:43 -0300 From: Glauber Costa MIME-Version: 1.0 Subject: Re: [PATCH v3 6/7] tcp buffer limitation: per-cgroup limit References: <1316393805-3005-1-git-send-email-glommer@parallels.com> <1316393805-3005-7-git-send-email-glommer@parallels.com> <4E7DDB82.3030802@parallels.com> <20110926200247.c80f7e47.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20110926200247.c80f7e47.kamezawa.hiroyu@jp.fujitsu.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: KAMEZAWA Hiroyuki Cc: Greg Thelen , linux-kernel@vger.kernel.org, paul@paulmenage.org, lizf@cn.fujitsu.com, ebiederm@xmission.com, davem@davemloft.net, netdev@vger.kernel.org, linux-mm@kvack.org, kirill@shutemov.name On 09/26/2011 08:02 AM, KAMEZAWA Hiroyuki wrote: > On Sat, 24 Sep 2011 10:30:42 -0300 > Glauber Costa wrote: > >> On 09/22/2011 03:01 AM, Greg Thelen wrote: >>> On Sun, Sep 18, 2011 at 5:56 PM, Glauber Costa wrote: >>>> +static inline bool mem_cgroup_is_root(struct mem_cgroup *mem) >>>> +{ >>>> + return (mem == root_mem_cgroup); >>>> +} >>>> + >>> >>> Why are you adding a copy of mem_cgroup_is_root(). I see one already >>> in v3.0. Was it deleted in a previous patch? >> >> Already answered by another good samaritan. >> >>>> +static int tcp_write_maxmem(struct cgroup *cgrp, struct cftype *cft, u64 val) >>>> +{ >>>> + struct mem_cgroup *sg = mem_cgroup_from_cont(cgrp); >>>> + struct mem_cgroup *parent = parent_mem_cgroup(sg); >>>> + struct net *net = current->nsproxy->net_ns; >>>> + int i; >>>> + >>>> + if (!cgroup_lock_live_group(cgrp)) >>>> + return -ENODEV; >>> >>> Why is cgroup_lock_live_cgroup() needed here? Does it protect updates >>> to sg->tcp_prot_mem[*]? >>> >>>> +static u64 tcp_read_maxmem(struct cgroup *cgrp, struct cftype *cft) >>>> +{ >>>> + struct mem_cgroup *sg = mem_cgroup_from_cont(cgrp); >>>> + u64 ret; >>>> + >>>> + if (!cgroup_lock_live_group(cgrp)) >>>> + return -ENODEV; >>> >>> Why is cgroup_lock_live_cgroup() needed here? Does it protect updates >>> to sg->tcp_max_memory? >> >> No, that is not my understanding. My understanding is this lock is >> needed to protect against the cgroup just disappearing under our nose. >> > > Hm. reference count of dentry for cgroup isn't enough ? > > Thanks, > -Kame > think think think think think think... Yeah, I guess it is. -- 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