vn3: MBR magic not found; assume a COMPATIBILITY_SLICE (s0)
panic: assertion "(count & VREF_MASK) > 0" failed in vrele at /usr/src/sys/kern/vfs_lock.c:354
cpuid = 5
Trace beginning at frame 0xfffff80117f53438
vrele() at vrele+0xc9 0xffffffff806f6ec9 
vrele() at vrele+0xc9 0xffffffff806f6ec9 
ext2_reclaim() at ext2_reclaim+0x6b 0xffffffff8260827b 
vop_reclaim() at vop_reclaim+0x4b 0xffffffff8070b3cb 
vgone_vxlocked() at vgone_vxlocked+0x266 0xffffffff806f5cf6 
vflush_scan() at vflush_scan+0x208 0xffffffff806fb3c8 
Debugger("panic")

CPU5 stopping CPUs: 0x0000001f
 stopped
Stopped at      Debugger+0x7c:  movb    $0,0xbdaf09(%rip)
db>