Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264092AbTKJTcs (ORCPT ); Mon, 10 Nov 2003 14:32:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264094AbTKJTcs (ORCPT ); Mon, 10 Nov 2003 14:32:48 -0500 Received: from notes.hallinto.turkuamk.fi ([195.148.215.149]:26386 "EHLO notes.hallinto.turkuamk.fi") by vger.kernel.org with ESMTP id S264092AbTKJTco (ORCPT ); Mon, 10 Nov 2003 14:32:44 -0500 Message-ID: <3FAFE8D5.4020102@kolumbus.fi> Date: Mon, 10 Nov 2003 21:36:53 +0200 From: =?ISO-8859-1?Q?Mika_Penttil=E4?= User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Manfred Spraul CC: Petr Vandrovec , Dave Jones , linux-kernel@vger.kernel.org Subject: Re: EFAULT reading /dev/mem... - broken x86info References: <20031108162737.GB26350@vana.vc.cvut.cz> <20031110161114.GM10144@redhat.com> <3FAFC1D1.3090309@colorfullife.com> <20031110165654.GS10144@redhat.com> <3FAFC831.4090108@colorfullife.com> <20031110180551.GA20168@vana.vc.cvut.cz> <3FAFDFFF.70100@colorfullife.com> In-Reply-To: <3FAFDFFF.70100@colorfullife.com> X-MIMETrack: Itemize by SMTP Server on marconi.hallinto.turkuamk.fi/TAMK(Release 5.0.8 |June 18, 2001) at 10.11.2003 21:34:33, Serialize by Router on notes.hallinto.turkuamk.fi/TAMK(Release 5.0.10 |March 22, 2002) at 10.11.2003 21:33:49, Serialize complete at 10.11.2003 21:33:49 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1016 Lines: 39 Manfred Spraul wrote: > Petr Vandrovec wrote: > >> On Mon, Nov 10, 2003 at 06:17:37PM +0100, Manfred Spraul wrote: >> >> >>> DEBUG_PAGEALLOC unmaps pages on kmem_cache_free and __free_pages(). >>> The pages are mapped again during get_free_pages and kmem_cache_alloc. >>> >>> 0x86000 looks like a normal page - what guarantees that it's not >>> used by the kernel? >>> >> >> >> With DEBUG_PAGEALLOC there is no problem with page if it is USED by >> the kernel. >> Problem is if page is NOT USED - in this case kernel does not have it >> in its >> mapping, and bad thing happen. >> >> > If the page is used by AGP, then it won't have a mapping either. > afaics, agp uses change_apge_attr() to turn on NOCACHE bit, and doesn't remove the mapping. --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/