Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262079AbUCLMqy (ORCPT ); Fri, 12 Mar 2004 07:46:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262088AbUCLMqy (ORCPT ); Fri, 12 Mar 2004 07:46:54 -0500 Received: from holomorphy.com ([207.189.100.168]:22533 "EHLO holomorphy.com") by vger.kernel.org with ESMTP id S262079AbUCLMqw (ORCPT ); Fri, 12 Mar 2004 07:46:52 -0500 Date: Fri, 12 Mar 2004 04:46:38 -0800 From: William Lee Irwin III To: Andrea Arcangeli Cc: Rik van Riel , Hugh Dickins , Ingo Molnar , Andrew Morton , torvalds@osdl.org, linux-kernel@vger.kernel.org Subject: Re: anon_vma RFC2 Message-ID: <20040312124638.GR655@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Andrea Arcangeli , Rik van Riel , Hugh Dickins , Ingo Molnar , Andrew Morton , torvalds@osdl.org, linux-kernel@vger.kernel.org References: <20040311135608.GI30940@dualathlon.random> <20040312122127.GQ30940@dualathlon.random> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040312122127.GQ30940@dualathlon.random> User-Agent: Mutt/1.5.5.1+cvs20040105i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1099 Lines: 23 On Fri, Mar 12, 2004 at 01:21:27PM +0100, Andrea Arcangeli wrote: > you missed the fact mremap doesn't work, that's the fundamental reason > for the vma tracking, so you can use vm_pgoff. > if you take Hugh's anonmm, mremap will be attaching a persistent dynamic > overhead to the vma it touches. Currently it does in form of pte_chains, > that can be converted to other means of overhead, but I simply don't > like it. > I like all vmas to be symmetric to each other, without special hacks to > handle mremap right. > We have the vm_pgoff to handle mremap and I simply use that. Absolute guarantees are nice but this characterization is too extreme. The case where mremap() creates rmap_chains is so rare I never ever saw it happen in 6 months of regular practical use and testing. Their creation could be triggered only by remap_file_pages(). -- wli - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/