From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759728AbZEFM2V (ORCPT ); Wed, 6 May 2009 08:28:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755796AbZEFM2H (ORCPT ); Wed, 6 May 2009 08:28:07 -0400 Received: from mx2.redhat.com ([66.187.237.31]:36364 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754086AbZEFM2F (ORCPT ); Wed, 6 May 2009 08:28:05 -0400 Message-ID: <4A0181EA.3070600@redhat.com> Date: Wed, 06 May 2009 08:26:18 -0400 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Thunderbird 2.0.0.17 (X11/20080915) MIME-Version: 1.0 To: Izik Eidus CC: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, aarcange@redhat.com, chrisw@redhat.com, alan@lxorguk.ukuu.org.uk, device@lanana.org, linux-mm@kvack.org, hugh@veritas.com, nickpiggin@yahoo.com.au Subject: Re: [PATCH 2/6] ksm: dont allow overlap memory addresses registrations. References: <1241475935-21162-1-git-send-email-ieidus@redhat.com> <1241475935-21162-2-git-send-email-ieidus@redhat.com> <1241475935-21162-3-git-send-email-ieidus@redhat.com> <4A00DD4F.8010101@redhat.com> <4A015C69.7010600@redhat.com> In-Reply-To: <4A015C69.7010600@redhat.com> 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 Izik Eidus wrote: > Rik van Riel wrote: >> Izik Eidus wrote: >>> subjects say it all. >> >> Not a very useful commit message. >> >> This makes me wonder, though. >> >> What happens if a user mmaps a 30MB memory region, registers it >> with KSM and then unmaps the middle 10MB? > > User cant break 30MB into smaller one. The user can break up the underlying VMAs though. I am just wondering out loud if we really want two VMA-like objects in the kernel, the VMA itself and a separate KSM object, with different semantics. Maybe this is fine, but I do think it's a question that needs to be thought about. -- All rights reversed.