Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752716AbYCIL4e (ORCPT ); Sun, 9 Mar 2008 07:56:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751175AbYCIL4Y (ORCPT ); Sun, 9 Mar 2008 07:56:24 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:39622 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751163AbYCIL4Y (ORCPT ); Sun, 9 Mar 2008 07:56:24 -0400 Date: Sun, 9 Mar 2008 12:56:03 +0100 From: Ingo Molnar To: Linus Torvalds Cc: Arjan van de Ven , hans.rosenfeld@amd.com, linux-kernel@vger.kernel.org, Thomas Gleixner , "H. Peter Anvin" Subject: Re: bisected boot regression post 2.6.25-rc3.. please revert Message-ID: <20080309115603.GA951@elte.hu> References: <20080301105646.2c8620d9@laptopd505.fenrus.org> <20080303074620.GC5934@elte.hu> <20080303091304.GA17911@elte.hu> <47CC2A3D.1000307@linux.intel.com> <20080303174009.GA19131@elte.hu> <47CC451A.2060501@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1882 Lines: 48 * Linus Torvalds wrote: > > I'm half tempted to just do it as inline period ... any objections ? > > Yes, I object. I want to understand why it would matter. If this is a > compiler bug, it's a really rather bad one. And if it's just some > stupid bug in our pmd_bad() macro, I still want to know what the > problem was. ok, i think i figured it out: on PAE 32-bit we dont properly sign-extend to a 64-bit pmd value in the new pmd_bad() macro - so if any physical RAM is above 4GB (Arjan's laptop had 4GB of RAM in it?) then we'll start seeing those high bits. This definitely needs PAE and more than 4GB of RAM to trigger. The best fix is the one below (it should solve Arjan's regression with that now-reverted patch redone), as it is the right thing to do [that way sign auto-extend trickles over into PAGE_MASK as well]. It boots fine on a >4GB box of mine but changing the type of PAGE_SIZE affects _everything_ so i'll keep testing it and i'd suggest to delay this fix to shortly after -rc5 is released instead of risking -rc5 with such a late commit. I'll send this and the re-done hugetlbfs fix together early next week. Ingo Signed-off-by: Ingo Molnar Index: linux/include/asm-x86/page.h =================================================================== --- linux.orig/include/asm-x86/page.h +++ linux/include/asm-x86/page.h @@ -5,7 +5,7 @@ /* PAGE_SHIFT determines the page size */ #define PAGE_SHIFT 12 -#define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT) +#define PAGE_SIZE (_AC(1,L) << PAGE_SHIFT) #define PAGE_MASK (~(PAGE_SIZE-1)) #ifdef __KERNEL__ -- 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/