Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932299Ab1FGSb3 (ORCPT ); Tue, 7 Jun 2011 14:31:29 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:57097 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932285Ab1FGSb1 (ORCPT ); Tue, 7 Jun 2011 14:31:27 -0400 Date: Tue, 7 Jun 2011 11:30:45 -0700 From: Joel Becker To: Eric Dumazet Cc: Darren Hart , Peter Zijlstra , David Oliver , linux-kernel@vger.kernel.org, Shawn Bohrer , Zachary Vonler , KOSAKI Motohiro , Hugh Dickins , Thomas Gleixner , Ingo Molnar Subject: Re: Change in functionality of futex() system call. Message-ID: <20110607183044.GA1603@noexit.corp.google.com> Mail-Followup-To: Eric Dumazet , Darren Hart , Peter Zijlstra , David Oliver , linux-kernel@vger.kernel.org, Shawn Bohrer , Zachary Vonler , KOSAKI Motohiro , Hugh Dickins , Thomas Gleixner , Ingo Molnar References: <1307373819.3098.40.camel@edumazet-laptop> <1307376672.2322.167.camel@twins> <1307376989.2322.171.camel@twins> <1307377349.3098.65.camel@edumazet-laptop> <1307377782.2322.183.camel@twins> <1307378564.3098.67.camel@edumazet-laptop> <4DED1421.5000300@linux.intel.com> <1307383898.3098.90.camel@edumazet-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1307383898.3098.90.camel@edumazet-laptop> X-Burt-Line: Trees are cool. X-Red-Smith: Ninety feet between bases is perhaps as close as man has ever come to perfection. User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 978 Lines: 29 On Mon, Jun 06, 2011 at 08:11:38PM +0200, Eric Dumazet wrote: > Le lundi 06 juin 2011 ? 10:53 -0700, Darren Hart a ?crit : > > > > > If I understand the problem correctly, RO private mapping really doesn't > > make any sense and we should probably explicitly not support it, while > > special casing the RO shared mapping in support of David's scenario. > > > > We supported them in 2.6.18 kernels, apparently. This might sounds > stupid but who knows ? Trying to come up with a strawman for this sort of operation. What about a process that creates a private mapping and then creates threads with CLONE_VM? Would we CoW in that case? Joel -- Pitchers and catchers report. http://www.jlbec.org/ jlbec@evilplan.org -- 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/