From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx120.postini.com [74.125.245.120]) by kanga.kvack.org (Postfix) with SMTP id 0A7096B004D for ; Sun, 4 Mar 2012 02:43:45 -0500 (EST) Received: by bkwq16 with SMTP id q16so3361151bkw.14 for ; Sat, 03 Mar 2012 23:43:44 -0800 (PST) Message-ID: <4F531D2C.7090105@openvz.org> Date: Sun, 04 Mar 2012 11:43:40 +0400 From: Konstantin Khlebnikov MIME-Version: 1.0 Subject: Re: [PATCH 3.3] memcg: fix GPF when cgroup removal races with last exit References: <4F51E4B1.4010607@openvz.org> In-Reply-To: <4F51E4B1.4010607@openvz.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Hugh Dickins Cc: Andrew Morton , KAMEZAWA Hiroyuki , Johannes Weiner , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" Konstantin Khlebnikov wrote: > Hugh Dickins wrote: >> >> Konstantin, I've not yet looked into how this patch affects your >> patchsets; but I do know that this surreptitious-switch-to-root >> behaviour seemed nightmarish when I was doing per-memcg per-zone >> locking (particularly inside something like __activate_page(), where >> we del and add under a single lock), and unnecessary once you and I >> secure the memcg differently. So you may just want to revert this in >> patches for linux-next; but I've a suspicion that now we understand >> it better, this technique might still be usable, and more efficient. > > Yes, something like that. But, I must fix my "isolated-pages" counters first, > otherwise I just reintroduce this bug again. > I have thought little more and invented better approach: we can keep isolated pages counted in lruvec->lru_size[] and vmstat counters. Thus isolated pages will prevent removing it's memory cgroup. This method is more complicated than your tricky pushing pages to root lruvec, but it more generic and does not adds new page-counters. -- 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