panic in ffs (Re: hangs in nbufkv)

Matthew Dillon dillon at
Tue Oct 12 21:31:47 PDT 2004

:I don't know, how, but the bug seems triggered by upping the 
:net.inet.udp.maxdgram from 9216 (default) to 16384 (to match the NFS 
:client's wsize). Once I do that, the machine will either panic or just 
:hang a few minutes into the heavy NFS writing (Sybase  database dumps 
:from a Solaris server). Happened twice already...
:    -mi
:P.S. Thanks for prompt responses and advice, BTW!

    Interesting.  That's getting a bit outside the realm I can help
    with.  NFS and the network stack have been issues in FreeBSD 
    recently so its probably something related.  I do seem to
    recall that NFS takes a callback from the network protocol
    stack for input processing.

    One thing I would do is to try using a TCP NFS mount instead
    of a UDP NFS mount.  It might work better simply due to 
    exercising a different part of the network code.  The buffer
    cache has some NFS specific stuff in it, but unless it has 
    been completely ripped up there shouldn't be anything that
    would actually crash the machine.  My bets are on the 
    network stack's interaction with NFS rather then NFS's
    interaction with the buffer cache.

					Matthew Dillon 
					<dillon at>

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