NFS deadlock and status of nfs locking (rpc.lockd)
Martin Blapp
mb at imp.ch
Mon May 7 15:35:40 UTC 2007
Hi all,
We have 1-2 times per day a nfs deadlock on a busy 6.2 STABLE (1 week
old) server, and we suspect rpc.lockd to be the problem. Unfortunalty we depend
on a working rpc.lockd :-( . The problems did not occour on a FreeBSD 5.4
server, they just appeared after upgrading.
This is an excerpt from 'ps -auxwww' when the deadlock happened. But as I said,
we only supect that rpc.lockd is the real problem.
root 693 0.0 0.1 3248 2040 ?? Ss 11:08AM 0:00.05 rpc.lockd: serve 0 1 0 96 0 select
daemon 700 0.0 0.1 3200 1948 ?? I 11:08AM 0:00.00 rpc.lockd: clien 1 693 38 4 0 nfsloc
root 677 0.0 0.1 2968 1696 ?? Is 11:08AM 0:00.04 nfsd: master (nf 0 1 0 96 0 select
root 678 0.0 0.0 1324 716 ?? D 11:08AM 0:01.02 nfsd: server (nf 0 677 0 -4 0 ufs
root 679 0.0 0.0 1324 716 ?? D 11:08AM 0:00.12 nfsd: server (nf 0 677 0 -8 0 biord
root 680 0.0 0.0 1324 716 ?? D 11:08AM 0:00.15 nfsd: server (nf 0 677 0 -4 0 ufs
root 681 0.0 0.0 1324 716 ?? D 11:08AM 0:00.42 nfsd: server (nf 0 677 0 -4 0 ufs
The nfsd instances with 'ufs' are unkillable. Sometimes it helps to stop
rpc.lockd and to restart it. The master nfsd process is unkillable too.
The server is a SMP machine, HTT enabled.
Now I have some questions:
- Can rpc.lockd be the underlying problem for such a nfsd hang ?
- Anybody of you knows a fix which hasn't already MFCd which could cause this ?
- Anything I could do to get more debugging informations ? Is turning on
rpc.lockd debug information safe ? (run rpc.lockd with -d).
- Who is currently working on rpc.lockd ? What is the current status if I'd be
interested to work on it.
- One instance of the exported file systems is mounted via iscsi. What happens
if such a export is going away for some seconds, gets reconnected and then
appears again. How are nfs timeouts handled in such a case ? Could that be
the problem ? Unfortunatly we have seen such hangs with and without this
particular filesystem mounted, but it happens definitly a lot more with the
iscsi filesystem mounted.
--
Martin
Martin Blapp, <mb at imp.ch> <mbr at FreeBSD.org>
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