Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753497Ab0HTQfQ (ORCPT ); Fri, 20 Aug 2010 12:35:16 -0400 Received: from mtaout02-winn.ispmail.ntl.com ([81.103.221.48]:18830 "EHLO mtaout02-winn.ispmail.ntl.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752942Ab0HTQfO (ORCPT ); Fri, 20 Aug 2010 12:35:14 -0400 From: Ian Campbell To: Linus Torvalds Cc: linux-kernel@vger.kernel.org, stable@kernel.org, stable-review@kernel.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Greg KH , Jeremy Fitzhardinge In-Reply-To: <1282321974.12544.24.camel@zakaz.uk.xensource.com> References: <20100818203143.735033743@clark.site> <1282308887.3170.5439.camel@zakaz.uk.xensource.com> <1282321974.12544.24.camel@zakaz.uk.xensource.com> Content-Type: text/plain; charset="UTF-8" Date: Fri, 20 Aug 2010 17:35:01 +0100 Message-ID: <1282322101.12544.25.camel@zakaz.uk.xensource.com> Mime-Version: 1.0 X-Mailer: Evolution 2.30.2 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 62.200.22.2 X-SA-Exim-Mail-From: ijc@hellion.org.uk Subject: Re: [2/3] mm: fix up some user-visible effects of the stack guard page X-SA-Exim-Version: 4.2.1 (built Wed, 25 Jun 2008 17:14:11 +0000) X-SA-Exim-Scanned: Yes (on hopkins.hellion.org.uk) X-Cloudmark-Analysis: v=1.1 cv=DhNl2YeytwJssBBGe49HJX82LNDFEEVkpVB34RXKaPo= c=1 sm=0 a=isDwiucj6PoA:10 a=IkcTkHD0fZMA:10 a=D81oFJkc8IoVLJme2vkA:9 a=Q1nS95oSogborT46ncdgxXKyXDAA:4 a=QEXdDO2ut3YA:10 a=HpAAvcLHHh0Zw7uRqdWCyQ==:117 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1190 Lines: 34 On Fri, 2010-08-20 at 17:32 +0100, Ian Campbell wrote: > On Fri, 2010-08-20 at 09:07 -0700, Linus Torvalds wrote: > > > Actually, thinking some more about it, that may not be a good idea. > > Why? Simply because we may want to merge the vma's back together if > > you do munlock. And it won't (and mustn't) merge if the vm_flags > > differ in VM_GROWSDOWN. > > > > So I do think we want to keep VM_GROWSDOWN (and VM_GROWSUP on > PA-RISC) > > even across a vma split. > > I naively hacked something together and it did seem to work, but I > shared your worries about merging. > > > Of course, we could set a flag whether the vma really does have a > > guard page or not. > > Bits in vma->vm_flags seems to be in rather short supply :-( On the other hand the VMA merging is just an optimisation, isn't it? -- Ian Campbell Many people are desperately looking for some wise advice which will recommend that they do what they want to do. -- 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/