This looks like a fix for the NFS "Attempting to free lock with active block
list" panic. I know this is a RHEL4 bug, but for what it's worth, I can
reproduce it on FC3, with kernel-2.6.10-1.737_FC3 and kernel-2.6.10-1.770_FC3. I
could help testing any errata.

Bug duplicated for FC3, see bug #155367

With kernel-smp-2.6.9-5.0.5.EL (recompiled to include root-over-NFS) running in
a root-over-NFS setup (RHEL WS 4 client, RHEL AS 3 server) keeps giving me
"Kernel panic - not syncing: attempting to free lock with active block list"
right after the machine is booted (out of 10 or so reboots only once machine
have stayed up and even then for only about 2 minutes after the boot process
have finished).

I will be very happy to help debugging this and/or to test a potential fix.

P.S. I also found a related thread at http://lkml.org/lkml/2005/1/5/210

We've applied the above patch, with the 3 surrounding it, 4 total:

- http://linux.bkbits.net:8080/linux-2.6/cset@1.1966.3.21
- http://linux.bkbits.net:8080/linux-2.6/cset@1.1966.78.16
- http://linux.bkbits.net:8080/linux-2.6/cset@1.1966.78.17
- http://linux.bkbits.net:8080/linux-2.6/cset@1.1982.115.2

After that the "Kernel panic - not syncing" would not happen, but under similar
condition a weird "temporary freze" would still happen (at the same time the
server will be spewing "RPC: error 5 connecting to server <_client's_ IP
address>" every 10 seconds or so) - see bug 140319 comment 12 for detail.

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2005-420.html