From owner-freebsd-current@FreeBSD.ORG Sat Jun 16 03:22:07 2007 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id B6C6616A400 for ; Sat, 16 Jun 2007 03:22:07 +0000 (UTC) (envelope-from Benjamin.Close@clearchain.com) Received: from ipmail03.adl2.internode.on.net (ipmail03.adl2.internode.on.net [203.16.214.135]) by mx1.freebsd.org (Postfix) with ESMTP id 34D0013C447 for ; Sat, 16 Jun 2007 03:22:06 +0000 (UTC) (envelope-from Benjamin.Close@clearchain.com) X-IronPort-AV: E=Sophos;i="4.16,428,1175437800"; d="scan'208";a="103684345" Received: from ppp141-200.lns11.adl6.internode.on.net (HELO mail.clearchain.com) ([121.45.141.200]) by ipmail03.adl2.internode.on.net with ESMTP; 16 Jun 2007 12:52:05 +0930 Received: from [192.168.155.252] (draco.internal.clearchain.com [192.168.155.252]) (authenticated bits=0) by mail.clearchain.com (8.13.8/8.13.8) with ESMTP id l5G3LlD9009801 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sat, 16 Jun 2007 12:51:48 +0930 (CST) (envelope-from Benjamin.Close@clearchain.com) Message-ID: <46735745.5000401@clearchain.com> Date: Sat, 16 Jun 2007 12:51:41 +0930 From: Benjamin Close User-Agent: Thunderbird 2.0.0.4 (Windows/20070604) MIME-Version: 1.0 To: Kris Kennaway References: <4672945C.3060304@clearchain.com> <20070615182521.GB9619@rot13.obsecurity.org> In-Reply-To: <20070615182521.GB9619@rot13.obsecurity.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: ClamAV version 0.90.3, clamav-milter version 0.90.3 on pegasus.clearchain.com X-Virus-Status: Clean X-Greylist: Sender succeeded SMTP AUTH authentication, not delayed by milter-greylist-2.0.2 (mail.clearchain.com [192.168.154.1]); Sat, 16 Jun 2007 12:51:48 +0930 (CST) X-Mailman-Approved-At: Sat, 16 Jun 2007 03:49:44 +0000 Cc: freebsd-current@freebsd.org Subject: Re: Swapfile on ZFS & Deadlock 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, 16 Jun 2007 03:22:07 -0000 Kris Kennaway wrote: > On Fri, Jun 15, 2007 at 11:00:04PM +0930, Benjamin Close wrote: > >> Hi All, >> Whilst running out of memory compiling Xorg (scanPCI is a killer) I >> discovered a quick way to deadlock the system: >> >> dd if=/dev/zero of=somefileonzfs bs=something count=something >> mdconfig -a -f something >> swapon /dev/md0 >> >> Then do something that needs swap.. instant deadlock. The system is >> still responsive but all disk access become hung. >> >> Known issue? If so is there a way we can warn users/prevent users from >> doing it? >> > > Enable DEBUG_VFS_LOCKS and DEBUG_LOCKS, then break to DDB when the > deadlock occurs and do 'show lockedvnods'. > Ok, enabled the above and this time got: swap_pager: indefinite wait buffer: bufobj: 0, blkno: 312865, size: 16384 just before the deadlock: Show locked vnods returns (hand transcribed) 0xffffff002c3ab5d0: tagz zfs, type VREG usecout 1, writecount 1, refcount 2 mountedhere 0 flags() v_object 0xffffff002f047c80 ref 0 pages 0 lock type zfs: EXCL (count 1) by thread 0xffffff0030573360 (pid 1188) Pid 1188 is: 1188 0 0 0 SL zfs:(&zi 0xffffff000208fd58 [md0] called doadump and though it went through the motions, savecore didn't find anything saved. Not sure what you need debugging wise, let me know. System is Intel Core 2 duo, running in SMP amd64, updated Friday 15th June. The box has 1G physical ram, 1G dedicated swap partition, but needs an extra 300M to compile xf86ScanPCI.c (freaky!). Figured a temp solution would be to allocate a 500M swap file on /var which is zfs. Cheers, Benjamin