Date: Sun, 5 Apr 2009 13:34:25 +0200 From: Stefan Bethke <stb@lassitu.de> To: Mark Powell <M.S.Powell@salford.ac.uk> Cc: freebsd-current@freebsd.org Subject: Re: panic: vput: negative ref cnt Message-ID: <98479514-21F9-4267-AD9F-DC697B7E0E0E@lassitu.de> In-Reply-To: <20090405120658.A24261@rust.salford.ac.uk> References: <20090404124909.C24261@rust.salford.ac.uk> <190B8595-BAF8-41F5-B63F-64604672BFD3@lassitu.de> <20090405120658.A24261@rust.salford.ac.uk>
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Am 05.04.2009 um 13:15 schrieb Mark Powell: > On Sun, 5 Apr 2009, Stefan Bethke wrote: > > Stefan, > Thanks for the input. > >> Am 04.04.2009 um 13:55 schrieb Mark Powell: >>> My script takes a zfs snapshot, mounts the snapshot, backs it up >>> using star, then umounts the snapshot. The panic seems to occur on >>> the umount. >> >> This is a different panic from the one I was getting, but appears >> to occur under the same circumstances. >> >> I managed to avoid the panic by keeping the snapshot until the next >> run of my backup script, and not unmounting anything. > > Yeah, I got around it by avoiding the unmount. > My script dates from 7-STABLE days, where a zfs bug caused the > automounted snapdir e.g. .zfs/snapshot/star_L0_2009-04-04-16:57, to > be missing a '..' entry. That prevented star from detecting that I > was performing a true full backup. Thus my script directly mounted > the snapshot to get a proper fs with a '..' entry and unmounted it > when finished. > Now the included version of zfs in 8-CURRENT doesn't have that bug > any longer. So I've reverted to backing up the automounted snapdir. > Consequently as I don't perform a mount I don't have to unmount > either, effectively working around the bug. > >> See <http://lists.freebsd.org/pipermail/freebsd-current/2009-February/003513.html >> > > > Do you know if a PR has been submitted for this one? When I lasted searched for it about six weeks ago, I couldn't find any. I wanted to reproduce the panic in VMware first to gather more details, but I've been unsuccessful in triggering it there at all. Maybe I need to switch my production boxes over to VMware :-) Stefan -- Stefan Bethke <stb@lassitu.de> Fon +49 151 14070811
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