From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d12nrmr1607.megacenter.de.ibm.com (d12nrmr1607.megacenter.de.ibm.com [9.149.167.49]) by mtagate6.de.ibm.com (8.13.8/8.13.8) with ESMTP id kB7A799h272394 for ; Thu, 7 Dec 2006 10:07:09 GMT Received: from d12av02.megacenter.de.ibm.com (d12av02.megacenter.de.ibm.com [9.149.165.228]) by d12nrmr1607.megacenter.de.ibm.com (8.13.6/8.13.6/NCO v8.1.1) with ESMTP id kB7A79Og3018828 for ; Thu, 7 Dec 2006 11:07:09 +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 kB7A78mP006099 for ; Thu, 7 Dec 2006 11:07:09 +0100 Date: Thu, 7 Dec 2006 11:06:59 +0100 From: Heiko Carstens Subject: Re: [RFC][PATCH] vmemmap on sparsemem v2 [1/5] generic vmemmap on sparsemem Message-ID: <20061207100659.GA9059@osiris.ibm.com> References: <20061205214517.5ad924f6.kamezawa.hiroyu@jp.fujitsu.com> <20061205214902.b8454d67.kamezawa.hiroyu@jp.fujitsu.com> <20061206181317.GA10042@osiris.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: KAMEZAWA Hiroyuki , linux-mm@kvack.org, clameter@engr.sgi.com, apw@shadowen.org List-ID: On Wed, Dec 06, 2006 at 10:17:04AM -0800, Christoph Lameter wrote: > On Wed, 6 Dec 2006, Heiko Carstens wrote: > > > > + vmap_start = (unsigned long)pfn_to_page(section_nr_to_pfn(section)); > > > + vmap_end = vmap_start + PAGES_PER_SECTION * sizeof(struct page); > > > + > > > + for (vmap = vmap_start; > > > + vmap != vmap_end; > > > + vmap += PAGE_SIZE) > > > + { > > > > Hmm.. maybe I'm just too tired. But why does this work? Why is vmap_start > > PAGE_SIZE aligned and why is vmap_end PAGE_SIZE aligned too? > > vmap_start is page aligned because pfn_to_page returns a page address. > Pages are page aligned. I must be dreaming... I always though pfn_to_page return the address to the beloging 'struct page'... and indeed it does. So there is nothing that guarantees that this is page aligned. -- 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