From owner-freebsd-stable@FreeBSD.ORG Wed Nov 16 14:33:04 2011 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id B132A1065674; Wed, 16 Nov 2011 14:33:04 +0000 (UTC) (envelope-from mavbsd@gmail.com) Received: from mail-ey0-f182.google.com (mail-ey0-f182.google.com [209.85.215.182]) by mx1.freebsd.org (Postfix) with ESMTP id 1A33A8FC1E; Wed, 16 Nov 2011 14:33:03 +0000 (UTC) Received: by eyd10 with SMTP id 10so753931eyd.13 for ; Wed, 16 Nov 2011 06:33:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=sender:message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=VLA16HeM6UCLIQnpAXHKYC8KFjqsJU30xLvMVBqbMTs=; b=ueWPuZavmLZN5y71pIHVezhzeu4LmumDNAu8GGsT3WVnFpssaj9yd/EcYR4uBQwqBa a0E0SO/ITBnXhIsYJIjUiSMVxmtBhL3HgablPXAjbNLuslRaNfc7m7Wgypu1GvWQqL/i QgjadtGGjnffm0OZrTF289ty8HZpMz71EB7ms= Received: by 10.213.4.140 with SMTP id 12mr1233430ebr.106.1321453982978; Wed, 16 Nov 2011 06:33:02 -0800 (PST) Received: from mavbook2.mavhome.dp.ua (pc.mavhome.dp.ua. [212.86.226.226]) by mx.google.com with ESMTPS id f36sm80184393eef.4.2011.11.16.06.33.01 (version=TLSv1/SSLv3 cipher=OTHER); Wed, 16 Nov 2011 06:33:01 -0800 (PST) Sender: Alexander Motin Message-ID: <4EC3C99C.8020203@FreeBSD.org> Date: Wed, 16 Nov 2011 16:33:00 +0200 From: Alexander Motin User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:7.0.1) Gecko/20111003 Thunderbird/7.0.1 MIME-Version: 1.0 To: "Bjoern A. Zeeb" References: <4EC392DA.2030302@FreeBSD.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: freebsd-stable@freebsd.org Subject: Re: ATA/Cdrom(?) panic X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 16 Nov 2011 14:33:04 -0000 On 11/16/11 16:14, Bjoern A. Zeeb wrote: > On Wed, 16 Nov 2011, Alexander Motin wrote: > >> Hi. >> >> On 11/16/11 08:43, Bjoern A. Zeeb wrote: >>> we have seen this or a very similar panic for about 1 year now once in >>> a while and I think I reported it before; this is FreeBSD as guest on >>> vmware. Seems it was a double panic this time. Could someone please >>> see what's going on there? It was on 8.x-STABLE in the past and this >>> is 8.2-RELEASE-p4. >> >> The part of code reporting "completing request directly" is IMHO broken >> by design. It returns request completion before request will actually be >> completed by lower levels without any knowledge of what's going on >> there. There is kind of protection against double request completion, >> but it looks like not always working. May be because that part of code >> is not locked and nothing prevents that semaphore timeout and normal >> request timeout/completion to happen simultaneously. It is surprising to >> see even two traps same time, not sure what synchronized them so >> precisely. >> >> Simple removing that semaphore timeout is not an option, because it will >> cause deadlock when this wait happen within taskqueue thread that is >> used to handle requests completion and abort that wait. Avoid waiting >> inside taskqueue is also impossible without major rewrite. That's why >> ATA_CAM drops that code completely. > > So the bottom line of what you are saying is: > 1) it's hard to fix right in 8 > 2) it's not an issue in 9 anymore at all? Right. -- Alexander Motin