Date: Wed, 31 Oct 2007 07:37:30 -0500 (CDT) From: "Matthew D. Fuller" <fullermd@over-yonder.net> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/117716: Remount can corrupt filesystems and lock them mounted Message-ID: <20071031123730.CC66220F25@mortis.over-yonder.net> Resent-Message-ID: <200710311240.l9VCe3oH033346@freefall.freebsd.org>
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>Number: 117716 >Category: kern >Synopsis: Remount can corrupt filesystems and lock them mounted >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Wed Oct 31 12:40:03 UTC 2007 >Closed-Date: >Last-Modified: >Originator: Matthew D. Fuller >Release: FreeBSD 8.0-CURRENT i386 >Organization: >Environment: System: FreeBSD mortis.sighup.org 8.0-CURRENT FreeBSD 8.0-CURRENT #0: Sat Oct 27 12:13:10 CDT 2007 root@mortis.sighup.org:/usr/ports/KERNELOBJ/sys/MORTIS i386 >Description: Attempting to remount a filesystem fails to flush its outstanding buffers, and spews out errors like softdep_waitidle: Failed to flush worklist for 0xc3b60d0c Once this occurs the filesystem can't be re-mounted, can't be umount'd, and can't be umount -f'd. Any attempt to do so will elicit a repeat of the softdep_waitidle message. Reboot won't cleanly unmount it either. Post-reboot fscking turns up a lot of errors. Using umount instead of mount -u doesn't provoke it (or at least, does so MUCH less often; mount -u does it reliably). If filesystem is made without softupdates, it also doesn't occur. This has been going on for at least a year in -CURRENT, and so it's probably in RELENG_7 too. See previous reports like <http://lists.freebsd.org/pipermail/freebsd-current/2007-February/069178.html>; >How-To-Repeat: NOTE: Running this script will produce a mounted filesystem on /mnt that can't be gotten rid of without rebooting. No additional instability has ever been observed from this, but be warned. #!/bin/sh -ex # Make file rm -f /tmp/fs dd if=/dev/zero of=/tmp/fs bs=1m count=20 # Make vnode mdconfig -a -t vnode -f /tmp/fs -u 10 # Make the filesystem newfs -U /dev/md10 # Mount mount /dev/md10 /mnt # Make the big tree mtree -deU -f /etc/mtree/BSD.usr.dist -p /mnt/ >> /dev/null # Sync up sync ; sync ; sync # Now blow it away rm -rf /mnt/* # This works... #umount /mnt # But this doesn't mount -u -o ro /mnt # BOOM. >Fix: >Release-Note: >Audit-Trail: >Unformatted:
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