From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [patch 13/26] Xen-paravirt_ops: Consistently wrap paravirt ops callsites to make them patchable Date: Tue, 20 Mar 2007 20:21:19 +0100 Message-ID: <20070320192118.GD4286@bingen.suse.de> References: <20070319.120854.30182994.davem@davemloft.net> <20070319.204712.118947830.davem@davemloft.net> <200703201428.50564.ak@suse.de> <20070320174159.GA4286@bingen.suse.de> <20070320180359.GB4286@bingen.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andi Kleen , "Eric W. Biederman" , David Miller , virtualization@lists.linux-foundation.org, jbeulich@novell.com, jeremy@goop.org, xen-devel@lists.xensource.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, chrisw@sous-sol.org, virtualization@lists.osdl.org, anthony@codemonkey.ws, akpm@linux-foundation.org, mingo@elte.hu To: Linus Torvalds Return-path: Received: from cantor2.suse.de ([195.135.220.15]:42293 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750699AbXCTSWa (ORCPT ); Tue, 20 Mar 2007 14:22:30 -0400 Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tue, Mar 20, 2007 at 10:27:00AM -0700, Linus Torvalds wrote: > > > On Tue, 20 Mar 2007, Andi Kleen wrote: > > > > The code never did that. In fact many of the problems we had initially > > especially came out of that -- the fallback code that would handle > > this case wasn't fully correct. > > I don't keep my emails any more, but you *never* fixed the problems in > arch/*/kernel/traps.c. I fixed that one after you dropped it (hmm, double checking: or at least I thought I had fixed it, but don't see the code right now; will redo then) Basically it was just a one liner anyways - always check against all the stacks that are there. > Yes, the kernel/unwind.c issues generally got fixed. The infinite loops in > the *callers* never did. There was later a weaker form that should have caught most loops, but admittedly it wasn't 100% bullet-proof with exception stacks. > > > Also frankly often your analysis about what went wrong was just > > incorrect. > > Still in denial, I see. > > Do you still claim that "the fallback position always did the right > thing" No initially it was buggy and that caused several of the crashes. > Despite the fact that the unwinder had sometimes *corrupted* the > incoming information so much that the fallback position was the one that > oopsed? And no, you didn't fix that. No, it oopsed because it was broken by itself. Anyways that got fixed quickly. > > And no, IT DID NOT use probe_kernel_address like you still claim. There definitely was a patch that made it use it. You might have not merged it though. > Anyway, you work for Suse, I don't care what you do to the Suse kernel. > Maybe it will get stable some day. Somehow, I doubt it. So what is your proposed alternative to handle long backtraces? You didn't answer that question. Please do, I'm curious about your thoughts in this area. -Andi