From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756649Ab0CVWky (ORCPT ); Mon, 22 Mar 2010 18:40:54 -0400 Received: from TYO201.gate.nec.co.jp ([202.32.8.193]:64156 "EHLO tyo201.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752475Ab0CVWkx (ORCPT ); Mon, 22 Mar 2010 18:40:53 -0400 Date: Fri, 19 Mar 2010 17:40:23 +0900 From: Naoya Horiguchi To: KAMEZAWA Hiroyuki Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, andi.kleen@intel.com, fengguang.wu@intel.com Subject: Re: [PATCH 2/2] [BUGFIX] pagemap: fix pfn calculation for hugepage Message-ID: <20100319084023.GC13107@spritzerA.linux.bs1.fc.nec.co.jp> References: <1268979996-12297-2-git-send-email-n-horiguchi@ah.jp.nec.com> <20100319161023.d6a4ea8d.kamezawa.hiroyu@jp.fujitsu.com> <20100319162732.58633847.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Content-Disposition: inline In-Reply-To: <20100319162732.58633847.kamezawa.hiroyu@jp.fujitsu.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 19, 2010 at 04:27:32PM +0900, KAMEZAWA Hiroyuki wrote: > On Fri, 19 Mar 2010 16:10:23 +0900 > KAMEZAWA Hiroyuki wrote: > > > On Fri, 19 Mar 2010 15:26:36 +0900 > > Naoya Horiguchi wrote: > > > > > When we look into pagemap using page-types with option -p, the value > > > of pfn for hugepages looks wrong (see below.) > > > This is because pte was evaluated only once for one vma > > > although it should be updated for each hugepage. This patch fixes it. > > > > > > $ page-types -p 3277 -Nl -b huge > > > voffset offset len flags > > > 7f21e8a00 11e400 1 ___U___________H_G________________ > > > 7f21e8a01 11e401 1ff ________________TG________________ > > > 7f21e8c00 11e400 1 ___U___________H_G________________ > > > 7f21e8c01 11e401 1ff ________________TG________________ > > > ^^^ > > > should not be the same > > > > > > With this patch applied: > > > > > > $ page-types -p 3386 -Nl -b huge > > > voffset offset len flags > > > 7fec7a600 112c00 1 ___UD__________H_G________________ > > > 7fec7a601 112c01 1ff ________________TG________________ > > > 7fec7a800 113200 1 ___UD__________H_G________________ > > > 7fec7a801 113201 1ff ________________TG________________ > > > ^^^ > > > OK > > > > > Hmm. Is this bug ? To me, it's just shown in hugepage's pagesize, by design. > > > I'm sorry it seems this is bugfix. > > But, this means hugeltb_entry() is not called per hugetlb entry...isn't it ? > Correct. Hugetlb_entry() is called per vma. > Why hugetlb_entry() cannot be called per hugeltb entry ? Don't we need a code > for a case as pmd_size != hugetlb_size in walk_page_range() for generic fix ? > Because in some architecture there is no generic means to know whether a pgd/pmd/pud/pte is hugetlb entry or not. For second question, vma-based walking is generic solution and works for "pmd_size != hugetlb_size" case. Thanks, Naoya Horiguchi