From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263847AbUE1Txr (ORCPT ); Fri, 28 May 2004 15:53:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263826AbUE1Txr (ORCPT ); Fri, 28 May 2004 15:53:47 -0400 Received: from fw.osdl.org ([65.172.181.6]:47773 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S263868AbUE1TxK (ORCPT ); Fri, 28 May 2004 15:53:10 -0400 Date: Fri, 28 May 2004 12:42:28 -0700 From: "Randy.Dunlap" To: Roland Dreier Cc: linux-kernel@vger.kernel.org Subject: Re: [Proposal] DEBUG_SLAB should select DEBUG_SPINLOCK Message-Id: <20040528124228.105ebcbb.rddunlap@osdl.org> In-Reply-To: <528yfc72u8.fsf@topspin.com> References: <528yfc72u8.fsf@topspin.com> Organization: OSDL X-Mailer: Sylpheed version 0.9.10 (GTK+ 1.2.10; i686-pc-linux-gnu) X-Face: +5V?h'hZQPB9kW Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 28 May 2004 12:45:35 -0700 Roland Dreier wrote: | I recently had a rather amusing debugging session. I developed some | code that worked fine on my test kernel, which had CONFIG_DEBUG_SLAB | turned on. However, as soon as I moved to a kernel without slab | debugging to do some benchmarks, I started getting lockups. It turns | out that I had a spinlock in my data structure that I forgot to | initialize but the poisoning from slab debugging had taken care of | initializing it for me. I didn't catch this during development | because I had left CONFIG_DEBUG_SPINLOCK off. | | Fortunately (for my sanity) I was able to diagnose this pretty quickly | with the help of the NMI oopser. However, for other developers' sake, | I think it might make sense to add | | select DEBUG_SPINLOCK | | to the DEBUG_SLAB stanza of Kconfig. | | I'm not posting a patch because I wanted to find out the status of | Randy Dunlap's patch that consolidates the debugging options. Is that | patch going to be merged, in someone's tree somewhere, dropped, or what? Andrew asked me to delay it until 2.6.6, which I did. Sent that, but not merged. I will be rediffing it and resending it again for 2.6.7 and probably some intermediate kernels if that's what it takes. | If the consensus is that we don't want to do this anyway, that's | fine. I mostly wanted to share this bug, which amused me. -- ~Randy