From owner-freebsd-stable@freebsd.org Tue Aug 9 09:47:47 2016 Return-Path: Delivered-To: freebsd-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id CC0A1BB38DD for ; Tue, 9 Aug 2016 09:47:47 +0000 (UTC) (envelope-from freebsd@omnilan.de) Received: from mx0.gentlemail.de (mx0.gentlemail.de [IPv6:2a00:e10:2800::a130]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4BE4E151F; Tue, 9 Aug 2016 09:47:47 +0000 (UTC) (envelope-from freebsd@omnilan.de) Received: from mh0.gentlemail.de (ezra.dcm1.omnilan.net [78.138.80.135]) by mx0.gentlemail.de (8.14.5/8.14.5) with ESMTP id u799ljYA085124; Tue, 9 Aug 2016 11:47:45 +0200 (CEST) (envelope-from freebsd@omnilan.de) Received: from titan.inop.mo1.omnilan.net (titan.inop.mo1.omnilan.net [IPv6:2001:a60:f0bb:1::3:1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mh0.gentlemail.de (Postfix) with ESMTPSA id 1DD55E7A; Tue, 9 Aug 2016 11:47:45 +0200 (CEST) Message-ID: <57A9A6C0.9060609@omnilan.de> Date: Tue, 09 Aug 2016 11:47:44 +0200 From: Harry Schmalzbauer Organization: OmniLAN User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; de-DE; rv:1.9.2.8) Gecko/20100906 Lightning/1.0b2 Thunderbird/3.1.2 MIME-Version: 1.0 To: Mark Johnston CC: Rick Macklem , FreeBSD Stable Subject: Re: unionfs bugs, a partial patch and some comments [Was: Re: 1-BETA3 Panic: __lockmgr_args: downgrade a recursed lockmgr nfs @ /usr/local/share/deploy-tools/RELENG_11/src/sys/fs/unionfs/union_vnops.c:1905] References: <57A79E24.8000100@omnilan.de> <57A83C78.1070403@omnilan.de> <20160809060213.GA67664@raichu> In-Reply-To: <20160809060213.GA67664@raichu> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit X-Greylist: ACL 119 matched, not delayed by milter-greylist-4.2.7 (mx0.gentlemail.de [78.138.80.130]); Tue, 09 Aug 2016 11:47:45 +0200 (CEST) X-Milter: Spamilter (Reciever: mx0.gentlemail.de; Sender-ip: 78.138.80.135; Sender-helo: mh0.gentlemail.de; ) X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 09 Aug 2016 09:47:47 -0000 Bezüglich Mark Johnston's Nachricht vom 09.08.2016 08:02 (localtime): … >> >> Just for anybody else needing unionfs: >> https://people.freebsd.org/~attilio/unionfs_missing_insmntque_lock.patch >> >> This patch still applies and I'm successfully using this (unmodified) up >> to FreeBSD-10.3 and never had any panic in all these years. > > Having spent some time looking at unionfs, I'm a bit skeptical that this > patch will address the panic you reported earlier, though I'd be > interested to know if it does. Thanks for your attention. I can confirm that it has prevented panics for more than 4 years (9.0-10.3) and it seems to be still "good enough" to also prevent panics in 11-BETA4. I updated my build host (stable/11, this time with the unionfs_missing_insmntque_lock.patch), where the recent panics happened and unionfs gets much more utilized than usually in my setups: No panic with that patch anymore. Just one message like "prevented resource deadlock" occured. > Reading the code, I think it will just > address an INVARIANTS-only assertion in insmntque1(). > > Unfortunately, unionfs is quite difficult to fix within the current > constraints of FreeBSD's VFS. unionfs_readdir() is a particularly good > demonstration of this fact: some callers of VOP_READDIR expect the > cookies returned by the FS to be monotonically increasing, but unionfs > has no straightforward way to make this guarantee. I'm sorry, I can't provide help here. My skills would require a huge ammount of lerning-time to get into that matter. I'd love to do that, but I can't afford :-( Thanks, -Harry