kern/50467: Panic from disconnecting phone while reading its contents

[coypu%sdf.org@localhost]

>Number:         50467
>Category:       kern
>Synopsis:       Panic from disconnecting phone while reading its contents
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Nov 24 21:05:00 +0000 2015
>Originator:     coypu
>Release:        NetBSD-current
>Organization:
>Environment:
NetBSD  7.99.21 NetBSD 7.99.21 (GENERIC.201511162220Z) #0: Mon Nov 16 23:08:55 UTC 2015  martin%b45.netbsd.org@localhost:/home/builds/ab/HEAD/amd64/201511162220Z-obj/home/source/ab/HEAD/src/sys/arch/amd64/compile/GENERIC amd64

>Description:
Connected smartphone via USB, mounted as msdos, copied files from it, disconnected cable (physically) in the middle, kernel panics.

smartphone is a Samsung S2 (I9100) running CyanogenMod 11 (Android ver 4.4.4)

Savecore available here:
http://coypu.sdf.org/netbsd.3.core.gz
http://coypu.sdf.org/netbsd.3.gz
>How-To-Repeat:
Connect smartphone by USB, mount -t msdos, cp files from it to local directory, disconnect cable mid copying.
>Fix: