From owner-freebsd-hackers@FreeBSD.ORG Mon Feb 9 14:38:03 2015 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 836B95C5 for ; Mon, 9 Feb 2015 14:38:03 +0000 (UTC) Received: from mail-lb0-x22d.google.com (mail-lb0-x22d.google.com [IPv6:2a00:1450:4010:c04::22d]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 03695A89 for ; Mon, 9 Feb 2015 14:38:03 +0000 (UTC) Received: by mail-lb0-f173.google.com with SMTP id n10so2968346lbv.4 for ; Mon, 09 Feb 2015 06:38:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=cVLjAtTYXZwBfF7tErVdhXF1WZMILk6dYp30pgF4rfw=; b=Omw+21X5oBWW7dZCP7RkIlTbhucNDbmopb5zfaIyEroyCb4JQ0/lkUsrkXvb3TI4cG opctei1xVBeqdBZxXg/9Peb5EQXaFdIo+gjN58VCG/APYeaoJK6mkd9CtNud79l6U9bE LNs4l3oH6z2+u7X8Aqt1e7pcdZkjbFOEqQcoOwK1bOdUPymgPrFj1kY1DfxzZGs0O2RX dsuysRSJ1gx3IXUcVXu/OEvvdngrsUTkkU0ByscPGWT7o7pfx3OZarw1iBeU5eS10KYz mYbm06XFkaGScBilC/aw3a9KXp47EnHvK27RglLjZoXHEv7JizPian7rJzUdutR7yUkj sd+A== MIME-Version: 1.0 X-Received: by 10.112.37.197 with SMTP id a5mr17584363lbk.19.1423492680786; Mon, 09 Feb 2015 06:38:00 -0800 (PST) Received: by 10.152.45.65 with HTTP; Mon, 9 Feb 2015 06:38:00 -0800 (PST) In-Reply-To: <20150209142242.GA8734@schlappy> References: <20150209142242.GA8734@schlappy> Date: Mon, 9 Feb 2015 16:38:00 +0200 Message-ID: Subject: Re: [unionfs] deadlocking a 9-STABLE machine with two unionfs mounts onto the same mountpoint From: Alexander Yerenkow To: Andre Albsmeier Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.18-1 Cc: "freebsd-hackers@freebsd.org" X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 09 Feb 2015 14:38:03 -0000 2015-02-09 16:22 GMT+02:00 Andre Albsmeier : > Retrying here as -fs didn't show up any results... > > ----- Forwarded message ----- > > I can reliably deadlock a 9.3-STABLE by the following procedure: > > Let's assume that /tmp is a standard swap-backed file system > already. First let's set up what we need: > > mkdir /tmp/1 /tmp/2 > mount -v -t unionfs /tmp/1 /usr/local > mount -v -t unionfs /tmp/2 /usr/local > Few years ago case was even simplier mkdir /tmp/1 mount -v -t unionfs /tmp/1 /usr/local #yep, just twice mount mount -v -t unionfs /tmp/1 /usr/local ls /tmp/1 #and the shell hangs. > > No let's lock the system: > > mkdir /tmp/2/bla > while :; do > echo go > tar -cC /usr/src/etc -f - . | tar -xpC /tmp/2/bla -f - > done > > It survives about 3 or 4 rounds, sometimes more, sometimes > only 2. It is important to use tar to copy the stuff. If > we replace the tar line by e.g. > > cp -pR /usr/src/etc/* /tmp/2/bla > > things are all well. > > The system doesn't lock up entirely, you can move the mouse > and ping it but no fs access is possible anymore. One can > switch to the console and enter the debugger but a reboot > with ctrl-alt-del doesn't work... > > The interesting part is that all this worked pretty well on > 9-STABLE until approx. 2 months ago. But nothing had been > committed to unionfs for a long time so I really have no > idea what's going on. > > It also reminds us of > > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=161511 > > but this stuff had been merged to 9-STABLE already... > > Anything I can do to get this fixed? > > ----- End forwarded message ----- > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" > -- Regards, Alexander Yerenkow