From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 91B446B004F for ; Thu, 12 Mar 2009 07:28:48 -0400 (EDT) Received: from d12nrmr1607.megacenter.de.ibm.com (d12nrmr1607.megacenter.de.ibm.com [9.149.167.49]) by mtagate7.de.ibm.com (8.14.3/8.13.8) with ESMTP id n2CBRv1R270488 for ; Thu, 12 Mar 2009 11:27:57 GMT Received: from d12av02.megacenter.de.ibm.com (d12av02.megacenter.de.ibm.com [9.149.165.228]) by d12nrmr1607.megacenter.de.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n2CBRvjv3145810 for ; Thu, 12 Mar 2009 12:27:57 +0100 Received: from d12av02.megacenter.de.ibm.com (loopback [127.0.0.1]) by d12av02.megacenter.de.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n2CBRuQO000672 for ; Thu, 12 Mar 2009 12:27:57 +0100 Date: Thu, 12 Mar 2009 12:24:41 +0100 From: Martin Schwidefsky Subject: Re: [PATCH] fix/improve generic page table walker Message-ID: <20090312122441.46782f9b@skybase> In-Reply-To: <20090312111916.5dbdb1e5@skybase> References: <20090311144951.58c6ab60@skybase> <1236792263.3205.45.camel@calx> <20090312093335.6dd67251@skybase> <20090312111916.5dbdb1e5@skybase> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Martin Schwidefsky Cc: Matt Mackall , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Gerald Schaefer , akpm@linux-foundation.org List-ID: On Thu, 12 Mar 2009 11:19:16 +0100 Martin Schwidefsky wrote: > On Thu, 12 Mar 2009 09:33:35 +0100 > Martin Schwidefsky wrote: > > > > I've gone to lengths to keep VMAs out of the equation, so I can't say > > > I'm excited about this solution. > > > > The minimum fix is to add the mmap_sem. If a vma is unmapped while you > > walk the page tables, they can get freed. You do have a dependency on > > the vma list. All the other page table walkers in mm/ start with the > > vma, then do the four loops. It would be consistent if the generic page > > table walker would do the same. > > > > Having thought about the problem again, I think I found a way how to > > deal with the problem in the s390 page table primitives. The fix is not > > exactly nice but it will work. With it s390 will be able to walk > > addresses outside of the vma address range. > > Ok, the patch below fixes the problem without vma operations in the > generic page table walker. We still need the mmap_sem part though. Hmm, thinko on my part. If would need the address of the pgd entry to do what I'm trying to achieve but I only have the pgd entry itself. Back to the vma operation in walk_page_range I'm afraid. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org