CURRENT r331284: crashing with USB

[Hyun Hwang]

On Wednesday, March 21, 2018, 11:41 PM (UTC-0600), Warner Losh <imp at bsdimp.com> wrote:
> Do you have a traceback?

This I got from core.txt:
```
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe000046e3c0
vpanic() at vpanic+0x18d/frame 0xfffffe000046e420
panic() at panic+0x43/frame 0xfffffe000046e480
dadone() at dadone+0x1cc9/frame 0xfffffe000046e9e0
xpt_done_process() at xpt_done_process+0x390/frame 0xfffffe000046ea20
xpt_done_td() at xpt_done_td+0xf6/frame 0xfffffe000046ea70
fork_exit() at fork_exit+0x84/frame 0xfffffe000046eab0
fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe000046eab0
```
Is this suffice? Full dump is available [here](https://www.amazon.com/clouddrive/share/48KzBn0452wRk6bS56oDu1MGXG8p8ug7TGsj8yhGkKN) if you need. (I'll  unshare this next month.)
Also, judging by the stack trace, this problem looks very similar to [this](https://lists.freebsd.org/pipermail/freebsd-current/2018-March/068900.html), I guess?

> actually, can you test https://reviews.freebsd.org/D14792 for me please?

I would love to and I can try, but...

> I won't be able to test until Friday

Same here, I cannot physically access the machine of interest until Friday. :(
-- 
Hyun Hwang