Hello,

I'm working on a NAS product and we're currently having lock-ups that
seem to be hanging in XFS code.  We're running a NAS that has 1024 NFSD
threads accessing three RAID mounts.  All three mounts are running XFS
file systems.  Lately we've had random lockups on these boxes and I am
now running a kernel with KDB built-in.

The lock-up takes the form of all NFSD threads in D state with one out
of three pdflush threads in D state.  The assumption can be made that
all NFSD threads are waiting on the one pdflush thread to complete.  So
two times now when an NAS has gotten in this state I have accessed KDB
and ran a stack trace on the pdflush thread.  Both times the thread was
stuck on xlog_grant_log_space+0xdb.  So now I'm turning to you to help
me figure out why XFS is locking up.  The box has been left in this
state so I can run and KDB commands you wish or if you have any
questions about the setup, let me know.  The system is running a mostly
stock 2.6.23.12 kernel.  My config file as well as photos taken of the
stack dump are attached.

Thanks,
Kris