From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261367AbTDDVef (for ); Fri, 4 Apr 2003 16:34:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261369AbTDDVef (for ); Fri, 4 Apr 2003 16:34:35 -0500 Received: from mail-2.tiscali.it ([195.130.225.148]:49126 "EHLO mail.tiscali.it") by vger.kernel.org with ESMTP id S261367AbTDDVed (for ); Fri, 4 Apr 2003 16:34:33 -0500 Date: Fri, 4 Apr 2003 23:45:47 +0200 From: Andrea Arcangeli To: Andrew Morton Cc: Hugh Dickins , dmccr@us.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: objrmap and vmtruncate Message-ID: <20030404214547.GB16293@dualathlon.random> References: <20030404105417.3a8c22cc.akpm@digeo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030404105417.3a8c22cc.akpm@digeo.com> User-Agent: Mutt/1.4i X-GPG-Key: 1024D/68B9CB43 X-PGP-Key: 1024R/CB4660B9 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 04, 2003 at 10:54:17AM -0800, Andrew Morton wrote: > Hugh Dickins wrote: > > > > Truncating a sys_remap_file_pages file? You're the first to > > begin to consider such an absurd possibility: vmtruncate_list > > still believes vm_pgoff tells it what needs to be done. > > Well I knew mincore() was bust for nonlinear mappings. Never thought about > truncate. IMHO sys_remap_file_pages and the nonlinear mapping is an hack and should be dropped eventually. I mean it's not too bad but it's a mere workaround for: 1) lack of 64bit address space that will be fixed 2) lack of O(log(N)) mmap, that will be fixed too 1) and 2) are the only reason why there's huge interest in such syscall right now. So I don't like it too much and I'm not convinced it was right to merge it in 2.5 given 2) is a software problem and I've the design to fix it with a rbtree extension, and 1) is an hardware problem that will be fixed very soon. the API is not too bad but there is a reason we have the vma for all other mappings. Maybe I'm missing something, I'm curious to hear what you think and what other cases needs this syscall even after 1) and 2) are fixed. Andrea