Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761000AbYCCVFZ (ORCPT ); Mon, 3 Mar 2008 16:05:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760329AbYCCVFA (ORCPT ); Mon, 3 Mar 2008 16:05:00 -0500 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:46021 "EHLO gprs189-60.eurotel.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760475AbYCCVE6 (ORCPT ); Mon, 3 Mar 2008 16:04:58 -0500 Date: Mon, 3 Mar 2008 22:05:26 +0100 From: Pavel Machek To: "Klaus S. Madsen" Cc: Ingo Molnar , Suspend-devel list , "H. Peter Anvin" , LKML , "Rafael J. Wysocki" , Thomas Gleixner , Matthew Garrett Subject: Re: Regression in 2.6.25-rc3: s2ram segfaults before suspending Message-ID: <20080303210526.GI13869@elf.ucw.cz> References: <20080228194920.GJ17932@hjernemadsen.org> <47C739A6.5020608@zytor.com> <20080229070028.GK17932@hjernemadsen.org> <47C873AA.6040305@zytor.com> <20080229212654.GL27212@elte.hu> <20080301094525.GQ17932@hjernemadsen.org> <20080303121735.GE28369@elf.ucw.cz> <20080303151155.GT17932@hjernemadsen.org> <20080303174858.GB25496@elte.hu> <20080303205227.GU17932@hjernemadsen.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080303205227.GU17932@hjernemadsen.org> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3363 Lines: 70 Hi! > However I wasn't able to make the problem go away, by removing the > _PAGE_PWT constants from __PAGE_KERNEL_NOCACHE and > __PAGE_KERNEL_VSYSCALL_NOCACHE in include-asm/pgtable.h in the newest > 2.6.25: > > diff --git a/include/asm-x86/pgtable.h b/include/asm-x86/pgtable.h > index 174b877..f81c968 100644 > --- a/include/asm-x86/pgtable.h > +++ b/include/asm-x86/pgtable.h > @@ -84,9 +84,9 @@ extern pteval_t __PAGE_KERNEL, __PAGE_KERNEL_EXEC; > #define __PAGE_KERNEL_RO (__PAGE_KERNEL & ~_PAGE_RW) > #define __PAGE_KERNEL_RX (__PAGE_KERNEL_EXEC & ~_PAGE_RW) > #define __PAGE_KERNEL_EXEC_NOCACHE (__PAGE_KERNEL_EXEC | _PAGE_PCD | _PAGE_PWT) > -#define __PAGE_KERNEL_NOCACHE (__PAGE_KERNEL | _PAGE_PCD | _PAGE_PWT) > +#define __PAGE_KERNEL_NOCACHE (__PAGE_KERNEL | _PAGE_PCD) > #define __PAGE_KERNEL_VSYSCALL (__PAGE_KERNEL_RX | _PAGE_USER) > -#define __PAGE_KERNEL_VSYSCALL_NOCACHE (__PAGE_KERNEL_VSYSCALL | _PAGE_PCD | _PAGE_PWT) > +#define __PAGE_KERNEL_VSYSCALL_NOCACHE (__PAGE_KERNEL_VSYSCALL | _PAGE_PCD) > #define __PAGE_KERNEL_LARGE (__PAGE_KERNEL | _PAGE_PSE) > #define __PAGE_KERNEL_LARGE_EXEC (__PAGE_KERNEL_EXEC | _PAGE_PSE) > > So while I'm fairly confident in that I bisected correctly, the number > of attempts I had to go through to get a reliable result, and the fact > that I cannot make the problem go away by reverting the current code to > something similar, counts quite a lot against me. > > However I'm 100% confident that the problem appears between > cf8fa920cb4271f17e0265c863d64bea1b31941a and > 925596a017bbd045ff711b778256f459e50a119, which is something like 16 > commits. I have been at both points in the tree at least 2 times, and > confirmed that cf8fa920cb4271f17e0265c863d64bea1b31941a worked for me, > and 925596a017bbd045ff711b778256f459e50a119 didn't. > > > while requiring PROT_EXEC is fine, breaking existing user-space apps > > over that is not fine. So are you absolutely sure that by reverting that > > PWT|PCD commit, s2ram again starts to work? That's utmost weird... > I'm sure that it fixed the problem for me, yes, and I'm fairly confident > that I ran make clean && make to compile the kernel during the entire > bisection between the two commites mentioned above. > > > perhaps there's some CPU bug that causes NX to _NOT_ work if only PCD is > > used (not PCD|PWT). Seems like a pretty unlikely scenario though. > $ cat /proc/cpuinfo > processor : 0 > vendor_id : GenuineIntel > cpu family : 6 > model : 15 > model name : Intel(R) Core(TM)2 Duo CPU T7500 @ 2.20GHz > stepping : 10 > > But I'm a bit puzzled by the fact that I'm aparently the only one how > have encountered the problem? Maybe it's only a problem if one also uses > PAE? (Thats just a wild guess to explain why I'm the only one seeing > this). I do not have NX capable CPU in machine using for suspend testing. ... and you are using 32-bit userspace on 64-bit kernel, right? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/