From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757480AbYEHBeL (ORCPT ); Wed, 7 May 2008 21:34:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751138AbYEHBd4 (ORCPT ); Wed, 7 May 2008 21:33:56 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:42341 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751025AbYEHBdy (ORCPT ); Wed, 7 May 2008 21:33:54 -0400 Date: Wed, 7 May 2008 18:32:11 -0700 (PDT) From: Linus Torvalds To: Christoph Lameter cc: Andrea Arcangeli , Andrew Morton , steiner@sgi.com, holt@sgi.com, npiggin@suse.de, a.p.zijlstra@chello.nl, kvm-devel@lists.sourceforge.net, kanojsarcar@yahoo.com, rdreier@cisco.com, swise@opengridcomputing.com, linux-kernel@vger.kernel.org, avi@qumranet.com, linux-mm@kvack.org, general@lists.openfabrics.org, hugh@veritas.com, rusty@rustcorp.com.au, aliguori@us.ibm.com, chrisw@redhat.com, marcelo@kvack.org, dada1@cosmosbay.com, paulmck@us.ibm.com Subject: Re: [PATCH 08 of 11] anon-vma-rwsem In-Reply-To: Message-ID: References: <6b384bb988786aa78ef0.1210170958@duo.random> <20080507212650.GA8276@duo.random> <20080507222205.GC8276@duo.random> <20080507153103.237ea5b6.akpm@linux-foundation.org> <20080507224406.GI8276@duo.random> <20080507155914.d7790069.akpm@linux-foundation.org> <20080507233953.GM8276@duo.random> User-Agent: Alpine 1.10 (LFD 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 7 May 2008, Christoph Lameter wrote: > On Wed, 7 May 2008, Linus Torvalds wrote: > > and you're now done. You have your "mm_lock()" (which still needs to be > > renamed - it should be a "mmu_notifier_lock()" or something like that), > > but you don't need the insane sorting. At most you apparently need a way > > to recognize duplicates (so that you don't deadlock on yourself), which > > looks like a simple bit-per-vma. > > Andrea's mm_lock could have wider impact. It is the first effective > way that I have seen of temporarily holding off reclaim from an address > space. It sure is a brute force approach. Well, I don't think the naming necessarily has to be about notifiers, but it should be at least a *bit* more scary than "mm_lock()", to make it clear that it's pretty dang expensive. Even without the vmalloc and sorting, if it would be used by "normal" things it would still be very expensive for some cases - running thngs like ElectricFence, for example, will easily generate thousands and thousands of vma's in a process. Linus