From owner-freebsd-current@FreeBSD.ORG Sat Feb 14 13:25:58 2009 Return-Path: Delivered-To: current@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 9073A1065673; Sat, 14 Feb 2009 13:25:58 +0000 (UTC) (envelope-from gallatin@cs.duke.edu) Received: from duke.cs.duke.edu (duke.cs.duke.edu [152.3.140.1]) by mx1.freebsd.org (Postfix) with ESMTP id 515D98FC1D; Sat, 14 Feb 2009 13:25:58 +0000 (UTC) (envelope-from gallatin@cs.duke.edu) Received: from [172.31.193.10] (cpe-075-177-134-250.nc.res.rr.com [75.177.134.250]) (authenticated bits=0) by duke.cs.duke.edu (8.14.2/8.14.2) with ESMTP id n1EDPEus011987 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sat, 14 Feb 2009 08:25:14 -0500 (EST) X-DKIM: Sendmail DKIM Filter v2.5.3 duke.cs.duke.edu n1EDPEus011987 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=cs.duke.edu; s=mail; t=1234617914; bh=ztr8/zf8iPd32zSRGNDvVblu/3WiLDoXXb/D3DDibmQ=; h=Message-ID:Date:From:MIME-Version:To:CC:Subject:References: In-Reply-To:Content-Type:Content-Transfer-Encoding; b=AsHD54C7XrZ9 RD/7P08j6oyPOBIbaQ49jTrmOOp7JGOK9nWojVJ3FPS7wawntBgbfci0fVbd3BME5/Q J3ut90SahTrGYwn2GkPE0tFF/qIXDipfeSYtz0fKSbdU19J3tPS6LCW71SfB483t1jb ou1/+nxD9fIh31W6YA+z4TFAg= Message-ID: <4996C62E.8090109@cs.duke.edu> Date: Sat, 14 Feb 2009 08:25:02 -0500 From: Andrew Gallatin User-Agent: Thunderbird 2.0.0.16 (X11/20080724) MIME-Version: 1.0 To: Robert Watson References: <4995A792.5050003@cs.duke.edu> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: current@FreeBSD.org Subject: Re: Dtrace panic'ed X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 14 Feb 2009 13:25:58 -0000 Robert Watson wrote: > > On Fri, 13 Feb 2009, Andrew Gallatin wrote: > >> I was trying to run a simple dtrace profiling script, and panic'ed the >> machine using today's -current on an 8-way opteron. > > Oh, you actually got a panic using the profile provider? For me the box > appears to go into la-la land. I've also seen a few double faults using > fbt a bit too gratuitously. Unfortunately, I haven't found time to > debug it, but I wondered if perhaps DTrace is not recognizing its own > functions (i.e., ones it shouldn't try to trace) properly and/or failing > to disable interrupts or enter a critical section at important moments. I think that sounds like a likely hypothesis. It is a shame it doesn't work. Dtrace's profile provider is so useful... BTW, did you see my next message where I was trying to find the null pointer? It seemed almost as if the state saved by the kernel crashdump was "correct" (eg, no NULL pointer), but the code was executing with a different, corrupt register set. It may just be my misunderstanding on amd64 asm though. As another aside, what is up with kgdb & module debug these days? It seems to load module symbols automagically these days, which is very cool. But the modules themselves do not seem to have symbols that gdb understands, even though I built with 'makeoptions DEBUG=-g' Drew