Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759345Ab1FWMwj (ORCPT ); Thu, 23 Jun 2011 08:52:39 -0400 Received: from smtp.eu.citrix.com ([62.200.22.115]:30345 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758959Ab1FWMwi (ORCPT ); Thu, 23 Jun 2011 08:52:38 -0400 X-IronPort-AV: E=Sophos;i="4.65,413,1304294400"; d="scan'208";a="6446554" Date: Thu, 23 Jun 2011 13:56:38 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball-desktop To: =?UTF-8?Q?Penttil=C3=A4_Mika?= CC: Stefano Stabellini , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] x86_64: do not assume head_64.S used 4KB pages when !use_pse In-Reply-To: <1A61D8EA6755AF458F06EA669A4EC8182F05B07E@JKLMAIL02.ixonos.local> Message-ID: References: <1A61D8EA6755AF458F06EA669A4EC8182F05B07E@JKLMAIL02.ixonos.local> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="8323329-615788323-1308833724=:12963" Content-ID: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2605 Lines: 70 --8323329-615788323-1308833724=:12963 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Content-ID: On Thu, 23 Jun 2011, Penttilä Mika wrote: > > From: Stefano Stabellini > > > head_64.S, which sets up the initial page table on x86_64, is not aware > > of PSE being enabled or disabled and it always allocates the initial > > mapping using 2MB pages. > > > Therefore on x86_64 find_early_table_space shouldn't update the amount > > of pages needed for pte pages depending on the size of the initial > > mapping, because we know for sure that no pte pages have been allocated > > yet. > > > Signed-off-by: Stefano Stabellini > > Reported-by: Ingo Molnar > > --- > > arch/x86/mm/init.c | 7 +++++++ > > 1 files changed, 7 insertions(+), 0 deletions(-) > > > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c > > index 36bacfe..1e3098b 100644 > > --- a/arch/x86/mm/init.c > > +++ b/arch/x86/mm/init.c > > @@ -42,12 +42,19 @@ static void __init find_early_table_space(unsigned long start, > > (PMD_SIZE * PTRS_PER_PMD)); > > pmd_mapped *= (PMD_SIZE * PTRS_PER_PMD); > > > > + /* > > + * On x86_64 do not limit the size we need to cover with 4KB pages > > + * depending on the initial allocation because head_64.S always uses > > + * 2MB pages. > > + */ > > +#ifdef CONFIG_X86_32 > > if (start < PFN_PHYS(max_pfn_mapped)) { > > if (PFN_PHYS(max_pfn_mapped) < end) > > size -= PFN_PHYS(max_pfn_mapped) - start; > > else > > size = 0; > > } > > +#endif > > And arch/x86/mm/init.c also has: > > #if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KMEMCHECK) > /* > * For CONFIG_DEBUG_PAGEALLOC, identity mapping will use small pages. > * This will simplify cpa(), which otherwise needs to support splitting > * large pages into small in interrupt context, etc. > */ > use_pse = use_gbpages = 0; > #else > use_pse = cpu_has_pse; > use_gbpages = direct_gbpages; > #endif > > > So big pages are also not used for DEBUG_PAGEALLOC and KMEMCHECK configs even if head_32.S did. Right, but that is not a problem because head_32.S always uses 4KB pages. --8323329-615788323-1308833724=:12963-- -- 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/