From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id 6E3066B004D for ; Fri, 2 Dec 2011 13:04:47 -0500 (EST) Message-ID: <4ED91318.1030803@parallels.com> Date: Fri, 2 Dec 2011 16:04:08 -0200 From: Glauber Costa MIME-Version: 1.0 Subject: Re: [PATCH v7 00/10] Request for Inclusion: per-cgroup tcp memory pressure References: <1322611021-1730-1-git-send-email-glommer@parallels.com> <20111130111152.6b1c7366.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20111130111152.6b1c7366.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: linux-kernel@vger.kernel.org, paul@paulmenage.org, lizf@cn.fujitsu.com, ebiederm@xmission.com, davem@davemloft.net, gthelen@google.com, netdev@vger.kernel.org, linux-mm@kvack.org, kirill@shutemov.name, avagin@parallels.com, devel@openvz.org, eric.dumazet@gmail.com, cgroups@vger.kernel.org On 11/30/2011 12:11 AM, KAMEZAWA Hiroyuki wrote: > On Tue, 29 Nov 2011 21:56:51 -0200 > Glauber Costa wrote: > >> Hi, >> >> This patchset implements per-cgroup tcp memory pressure controls. It did not change >> significantly since last submission: rather, it just merges the comments Kame had. >> Most of them are style-related and/or Documentation, but there are two real bugs he >> managed to spot (thanks) >> >> Please let me know if there is anything else I should address. >> > > After reading all codes again, I feel some strange. Could you clarify ? > > Here. > == > +void sock_update_memcg(struct sock *sk) > +{ > + /* right now a socket spends its whole life in the same cgroup */ > + if (sk->sk_cgrp) { > + WARN_ON(1); > + return; > + } > + if (static_branch(&memcg_socket_limit_enabled)) { > + struct mem_cgroup *memcg; > + > + BUG_ON(!sk->sk_prot->proto_cgroup); > + > + rcu_read_lock(); > + memcg = mem_cgroup_from_task(current); > + if (!mem_cgroup_is_root(memcg)) > + sk->sk_cgrp = sk->sk_prot->proto_cgroup(memcg); > + rcu_read_unlock(); > == > > sk->sk_cgrp is set to a memcg without any reference count. > > Then, no check for preventing rmdir() and freeing memcgroup. > > Is there some css_get() or mem_cgroup_get() somewhere ? > There were a css_get in the first version of this patchset. It was removed, however, because it was deemed anti-intuitive to prevent rmdir, since we can't know which sockets are blocking it, or do anything about it. Or did I misunderstand something ? -- 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