Date: Thu, 20 May 2010 23:24:21 -1000 (HST) From: Jeff Roberson <jroberson@jroberson.net> To: Erik Cederstrand <erik@cederstrand.dk> Cc: Attilio Rao <attilio@freebsd.org>, current@freebsd.org, Peter Jeremy <peterjeremy@acm.org> Subject: Re: LOR: ufs vs bufwait Message-ID: <alpine.BSF.2.00.1005202323320.1398@desktop> In-Reply-To: <ECB15F9F-F5FC-41FF-8A80-ED299AFE432F@cederstrand.dk> References: <20100508102005.GB1867@elmar.spoerlein.net> <20100510061057.GA93038@server.vk2pj.dyndns.org> <u2h3bbf2fe11005101353k493f3ca3v7c1216e840820c67@mail.gmail.com> <20100512141154.GF88504@acme.spoerlein.net> <alpine.BSF.2.00.1005121040390.1398@desktop> <ECB15F9F-F5FC-41FF-8A80-ED299AFE432F@cederstrand.dk>
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On Fri, 21 May 2010, Erik Cederstrand wrote: > > Den 12/05/2010 kl. 22.44 skrev Jeff Roberson: >> >> I think Peter Holm also saw this once while we were testing SUJ and reproduced ~30 second hangs with stock sources. At this point we need to brainstorm ideas for adding debugging instrumentation and come up with the quickest possible repro. > > FWIW, I get this LOR on a ClangBSD virtual machine running the stess2 test suite. > > I can reproduce the LOR reliably like this: > > # cd stress2 > #./run.sh lockf.cfg > - press ctrl-C > - another LOR is triggered by the ctrl-C (a dirhash/bufwait LOR described in kern/137852) > # ./run.sh mkdir.cfg > - LOR is triggered immediately > > Erik The LOR is actually safe. I need to bless the acquisition. We have always acquired the buffers in this order. The deadlocks people were seeing were actually livelocks due to softdepflush looping indefinitely. I have committed a fix for that. Thanks, Jeff
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