Sleeping on "fdesc" with the following non-sleepable locks held:

Found in 6.0 (with mpsafevm=1, if it matters)

Kris

Sleeping on "fdesc" with the following non-sleepable locks held:
exclusive sleep mutex fdesc r = 0 (0xc0740920) locked _at_ kern/vfs_mount.c:955
KDB: enter: witness_warn
[thread pid 79735 tid 100366 ]
Stopped at      kdb_enter+0x32: leave
db> tr
Tracing pid 79735 tid 100366 td 0xc8584900
kdb_enter(c06c48a8,f161bc28,1,1,0) at kdb_enter+0x32
witness_warn(2,c5bae928,c06e4bde,c06e0ca6,c076cbd0) at witness_warn+0x1bb
msleep(c5bae94c,c5bae928,64,c06e0ca6,0) at msleep+0x47
checkdirs(c59fa400,f161bca4,c8584900,c8584900,0) at checkdirs+0xe0
dounmount(c59fa400,8080000,c8584900,40d,602ff4f) at dounmount+0x3d6
unmount(c8584900,f161bd14,c06feff6,3ad,2) at unmount+0x1cc
syscall(2f,2f,2f,804a618,bfbfe759) at syscall+0x13b
Xint0x80_syscall() at Xint0x80_syscall+0x1f
--- syscall (22, FreeBSD ELF32, unmount), eip = 0x280c5a63, esp = 0xbfbfe4ec, ebp = 0xbfbfe5a8 ---