Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751452AbWI3WSS (ORCPT ); Sat, 30 Sep 2006 18:18:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751438AbWI3WSR (ORCPT ); Sat, 30 Sep 2006 18:18:17 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:3222 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S1751452AbWI3WSQ (ORCPT ); Sat, 30 Sep 2006 18:18:16 -0400 Date: Sun, 1 Oct 2006 00:10:05 +0200 From: Ingo Molnar To: Andi Kleen Cc: Linus Torvalds , Eric Rannaud , Linux Kernel Mailing List , Andrew Morton , nagar@watson.ibm.com, Chandra Seetharaman , Jan Beulich Subject: Re: BUG-lockdep and freeze (was: Arrr! Linux 2.6.18) Message-ID: <20060930221005.GA20839@elte.hu> References: <5f3c152b0609301220p7a487c7dw456d007298578cd7@mail.gmail.com> <200609302230.24070.ak@suse.de> <200610010002.46634.ak@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200610010002.46634.ak@suse.de> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: -2.8 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.8 required=5.9 tests=ALL_TRUSTED,AWL,BAYES_50 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts 0.5 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.5000] -0.0 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1079 Lines: 26 * Andi Kleen wrote: > > Why not just add the simple validation? > > > > A kernel stack is one page in size. If you move to another page, you > > terminate. It's that simple. > > No, it's not. On x86-64 it can be three or more stacks nested in > complicated ways (process stack, interrupt stack, exception stack) The > exception stack can happen multiple times. it could be cleanly handled though: in June i suggested to use the next-stack pointers at the end of exception pages. The only current complexity here is that the 'linking' of exception pages is non-uniform, it depends on the type of page. That's largely why that complex statemachine had to be implemented, to match up the type of the page. Since those pointers are put there by us, there's no real reason why we couldnt standardize them. Ingo - 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/