lock order reversal in r252098

[Steven Kreuzer]

Hello-

I am running 10.0-CURRENT #0 r252098 on a beaglebone and I am getting the
occasional LOR when reading/writing in an nfs mount

lock order reversal:
 1st 0xc1c0a150 newnfs (newnfs) @ /usr/src/sys/kern/vfs_syscalls.c:4064
 2nd 0xc6a5e278 bufwait (bufwait) @ /usr/src/sys/kern/vfs_bio.c:2311
 3rd 0xc1c12150 newnfs (newnfs) @ /usr/src/sys/kern/vfs_subr.c:2099
KDB: stack backtrace:
end() at 0xd52035b0
scp=0xd52035b0 rlv=0xc05108e0 (db_trace_self+0x14)
        rsp=0xd5203498 rfp=0xc057394f
Bad frame pointer: 0xc057394f

Shortly after, the beaglebone locks up and requires a power cycle

If anyone has any hints or can spare some cycles to help me debug this
issue, please let me know

Many Thanks