LOR: ufs vs bufwait
Jeff Roberson
jroberson at jroberson.net
Fri May 21 09:24:26 UTC 2010
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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