zio_done panic in 10.3

[Shiva Bhanujan]

Hello,

I'm getting a kernel panic in FreeBSD 10.3 p22 (r324806M).  

KDB: stack backtrace:
#0 0xffffffff80982fe0 at kdb_backtrace+0x60
#1 0xffffffff80945cb6 at vpanic+0x126
#2 0xffffffff80945b83 at panic+0x43
#3 0xffffffff80d4ac6b at trap_fatal+0x36b
#4 0xffffffff80d4af6d at trap_pfault+0x2ed
#5 0xffffffff80d4a5ea at trap+0x47a
#6 0xffffffff80d305b2 at calltrap+0x8
#7 0xffffffff8094db5d at _sx_xlock+0x5d
#8 0xffffffff81a4ccec at zio_done+0x92c
#9 0xffffffff81a486ea at zio_execute+0x10a
#10 0xffffffff80993e15 at taskqueue_run_locked+0xe5
#11 0xffffffff809948a8 at taskqueue_thread_loop+0xa8
#12 0xffffffff8090f13a at fork_exit+0x9a
#13 0xffffffff80d30aee at fork_trampoline+0xe

We are doing send/receive of zfs snapshots by piping it through mbuffer and netcat.   I can't seem to relate send/receive to the above backtrace.

The closest bug that I've found w/ a panic close to the above is as follows:

https://bugs.freebsd.org/bugzilla/show_bug.cgi?format=multiple&id=181966

I haven't been able to find any commits against this backtrace.  Can anybody please point me to anything that might have addressed this issue?   please let me know if there is any additional information that you might need.

Regards,
Shiva