Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759294Ab1FWMjt (ORCPT ); Thu, 23 Jun 2011 08:39:49 -0400 Received: from va3ehsobe003.messaging.microsoft.com ([216.32.180.13]:12820 "EHLO VA3EHSOBE003.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756339Ab1FWMjs convert rfc822-to-8bit (ORCPT ); Thu, 23 Jun 2011 08:39:48 -0400 X-SpamScore: -6 X-BigFish: VPS-6(zz1432Nzz1202hzz8275bhz2fh2a8h668h839h62h) X-Spam-TCS-SCL: 1:0 X-Forefront-Antispam-Report: CIP:80.242.17.33;KIP:(null);UIP:(null);IPVD:NLI;H:JKLMAIL02.ixonos.local;RD:po02.ixonos.com;EFVD:NLI From: =?iso-8859-1?Q?Penttil=E4_Mika?= To: "stefano.stabellini@eu.citrix.com" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] x86_64: do not assume head_64.S used 4KB pages when !use_pse Thread-Topic: Re: [PATCH] x86_64: do not assume head_64.S used 4KB pages when !use_pse Thread-Index: AcwxooNbw6hL5g5qQn2fMGfFtIoRyQ== Date: Thu, 23 Jun 2011 12:38:54 +0000 Message-ID: <1A61D8EA6755AF458F06EA669A4EC8182F05B07E@JKLMAIL02.ixonos.local> Accept-Language: en-US, fi-FI Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.200.5.70] Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT MIME-Version: 1.0 X-OriginatorOrg: ixonos.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2172 Lines: 67 > 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. --Mika -- 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/