From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750706AbWIHHgu (ORCPT ); Fri, 8 Sep 2006 03:36:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750714AbWIHHgu (ORCPT ); Fri, 8 Sep 2006 03:36:50 -0400 Received: from nz-out-0102.google.com ([64.233.162.202]:64492 "EHLO nz-out-0102.google.com") by vger.kernel.org with ESMTP id S1750706AbWIHHgt (ORCPT ); Fri, 8 Sep 2006 03:36:49 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=cfp5yTbCD0l3dqpZnFBvvzrZg03sUHlxaa/9EMcRxk4TGab8pEwhkrcgvdqkeu8i5ja4Ah5+SCuOtIWnvGTREVV4b0Zgxi7cfdi4Yjiqdg3WVPq8/p3PLMe2Xs67YvO1KBbwUbNuz/90QOIqxSnQdYO5Rcjc7Yq+LP8aov3GGMc= Message-ID: <24c1515f0609080036m21ffcef0ob576b5709e5ec6ce@mail.gmail.com> Date: Fri, 8 Sep 2006 10:36:48 +0300 From: "Janne Karhunen" To: linux-kernel@vger.kernel.org Subject: debugging a deadlock MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, Sometimes you have to do strange things such as trying to debug occasional deadlock of a system that has been in use for long, long time. So please, no nasty comments about outdated system with no soft lock-up detection and such :/ Anyhoo, it appears to be infinite semaphore wait. By modifying the semaphores to dump stack on LONG wait I managed to get a stack trace. Looks like this: kernel: [printk+340/384] [printk+340/384] [show_trace+203/240] [show_trace+203/240] [show_stack+113/120] [show_registers+223/324] kernel: [__down+147/276] [__down_failed+8/12] [stext_lock+13538/52069] [error_code+16/64] [system_call+66/76] Umm, this error_code thing is beyond my current knowledge. What's this? Some sort of assembly-glued exception handling? Any ideas how to figure out which semaphore this is? -- // Janne