Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759550Ab3DZC3P (ORCPT ); Thu, 25 Apr 2013 22:29:15 -0400 Received: from terminus.zytor.com ([198.137.202.10]:34818 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758203Ab3DZC3O (ORCPT ); Thu, 25 Apr 2013 22:29:14 -0400 Message-ID: <5179E652.808@zytor.com> Date: Thu, 25 Apr 2013 19:28:34 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 MIME-Version: 1.0 To: Simon Jeons CC: Minchan Kim , Sasha Levin , "Kirill A. Shutemov" , Andrew Morton , David Rientjes , Andrea Arcangeli , Mel Gorman , Dave Jones , linux-mm , "linux-kernel@vger.kernel.org" Subject: Re: mm: BUG in do_huge_pmd_wp_page References: <51559150.3040407@oracle.com> <20130410080202.GB21292@blaptop> <517861E0.7030801@zytor.com> <51786D52.1080509@gmail.com> In-Reply-To: <51786D52.1080509@gmail.com> X-Enigmail-Version: 1.5.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 684 Lines: 19 On 04/24/2013 04:40 PM, Simon Jeons wrote: > > I see in memblock_trim_memory(): start = round_up(orig_start, align); > here align is PAGE_SIZE, so the dump of zone ranges in my machine is [ > 0.000000] DMA [mem 0x00001000-0x00ffffff]. Why PFN 0 is not > used? just for align? > PFN 0 contains the real-mode interrupt vector table and BIOS data area, so we just reserve it. Avoids issues with zero being special, too. -hpa -- 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/