uma_zalloc_arg: zone "mbuf" with the following non-sleepable locks held: on today's amd64 kernel

'Fraid I'm not much of a kernel hacker, so advance apologies if this
turns out just to be noise - but I figure since I'm running current I
ought to report a few bugs.  If it turns out that this sort of thing
shouldn't be reported, just tell me ;)

I compiled a new kernel at 11:30am, and I've been writing to zfs via nfs
for a bit and these messages have been showing up:

Jul 12 19:52:25 universe kernel: uma_zalloc_arg: zone "mbuf" with the
following non-sleepable locks held:
Jul 12 19:52:25 universe kernel: exclusive sleep mutex nfsd_mtx r = 0
(0xffffffff80aad120) locked _at_ /usr/src/sys/nfsserver/nfs_srvsock.c:660
Jul 12 19:52:25 universe kernel: KDB: stack backtrace:
Jul 12 19:52:25 universe kernel: db_trace_self_wrapper() at
db_trace_self_wrapper+0x2a
Jul 12 19:52:25 universe kernel: witness_warn() at witness_warn+0x248
Jul 12 19:52:25 universe kernel: uma_zalloc_arg() at uma_zalloc_arg+0x33a
Jul 12 19:52:25 universe kernel: nfs_realign() at nfs_realign+0x63
Jul 12 19:52:25 universe kernel: nfsrv_rcv() at nfsrv_rcv+0x590
Jul 12 19:52:25 universe kernel: nfssvc() at nfssvc+0xb9f
Jul 12 19:52:25 universe kernel: syscall() at syscall+0x1ce
Jul 12 19:52:25 universe kernel: Xfast_syscall() at Xfast_syscall+0xab
Jul 12 19:52:25 universe kernel: --- syscall (155, FreeBSD ELF64,
nfssvc), rip = 0x8006891cc, rsp = 0x7fffffffea28, rbp = 0 ---
Jul 12 19:52:25 universe kernel: uma_zalloc_arg: zone "mbuf_cluster"
with the following non-sleepable locks held:
Jul 12 19:52:25 universe kernel: exclusive sleep mutex nfsd_mtx r = 0
(0xffffffff80aad120) locked _at_ /usr/src/sys/nfsserver/nfs_srvsock.c:660
Jul 12 19:52:25 universe kernel: KDB: stack backtrace:
Jul 12 19:52:25 universe kernel: db_trace_self_wrapper() at
db_trace_self_wrapper+0x2a
Jul 12 19:52:25 universe kernel: witness_warn() at witness_warn+0x248
Jul 12 19:52:25 universe kernel: uma_zalloc_arg() at uma_zalloc_arg+0x33a
Jul 12 19:52:25 universe kernel: nfs_realign() at nfs_realign+0x91
Jul 12 19:52:25 universe kernel: nfsrv_rcv() at nfsrv_rcv+0x590
Jul 12 19:52:25 universe kernel: nfssvc() at nfssvc+0xb9f
Jul 12 19:52:25 universe kernel: syscall() at syscall+0x1ce
Jul 12 19:52:25 universe kernel: Xfast_syscall() at Xfast_syscall+0xab
Jul 12 19:52:25 universe kernel: --- syscall (155, FreeBSD ELF64,
nfssvc), rip = 0x8006891cc, rsp = 0x7fffffffea28, rbp = 0 ---

I'm running:
FreeBSD universe.stevenschlansker.is-a-geek.org 7.0-CURRENT FreeBSD
7.0-CURRENT #1: Thu Jul 12 11:48:11 PDT 2007
root_at_universe.stevenschlansker.is-a-geek.org:/usr/obj/usr/src/sys/GENERIC
 amd64


Didn't do anything fancy - CVSup, buildworld buildkernel, install...

Hope that helps someone track down a bug :)

Steven Schlansker