From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758063Ab0D3Qze (ORCPT ); Fri, 30 Apr 2010 12:55:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50812 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757992Ab0D3QzL (ORCPT ); Fri, 30 Apr 2010 12:55:11 -0400 Message-ID: <4BD9A84C.3050709@redhat.com> Date: Thu, 29 Apr 2010 11:39:56 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.7) Gecko/20100120 Fedora/3.0.1-1.fc12 Lightning/1.0b2pre Thunderbird/3.0.1 MIME-Version: 1.0 To: Minchan Kim CC: Andrea Arcangeli , Mel Gorman , Linux-MM , LKML , KAMEZAWA Hiroyuki , Christoph Lameter , Andrew Morton Subject: Re: [RFC PATCH -v3] take all anon_vma locks in anon_vma_lock References: <1272403852-10479-1-git-send-email-mel@csn.ul.ie> <20100428153525.GR510@random.random> <20100428155558.GI15815@csn.ul.ie> <20100428162305.GX510@random.random> <20100428134719.32e8011b@annuminas.surriel.com> <20100428142510.09984e15@annuminas.surriel.com> <20100428161711.5a815fa8@annuminas.surriel.com> <20100428165734.6541bab3@annuminas.surriel.com> <4BD8EA85.2000209@redhat.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/28/2010 10:55 PM, Minchan Kim wrote: > When you tried anon_vma_chain patches as I pointed out, what I have a > concern is parent's vma not child's one. > The vma of parent still has N anon_vma. No, it is the other way around. The anon_vma of the parent is also present in all of the children, so the parent anon_vma is attached to N vmas. However, the parent vma only has 1 anon_vma attached to it, and each of the children will have 2 anon_vmas. That is what should keep any locking overhead with this patch minimal. Yes, a deep fork bomb can slow itself down. Too bad, don't do that :) -- All rights reversed