panic: vref: bad refcnt 00000000 1
cpuid = 2
Trace beginning at frame 0xfffff801180e37a8
vref() at vref+0x36 0xffffffff806f6bc6
vref() at vref+0x36 0xffffffff806f6bc6
devfs_fo_ioctl() at devfs_fo_ioctl+0x13f 0xffffffff80921c5f
mapped_ioctl() at mapped_ioctl+0x5fa 0xffffffff806a831a
syscall2() at syscall2+0x11e 0xffffffff80bd6a0e
Debugger("panic")
CPU2 stopping CPUs: 0x0000003b
 stopped
(secondary panic "Secondary PANIC on CPU 3/5" interleaved on the console;
 raw serial captures in panic1.txt / panic2.txt; both baseline runs
 produced this identical signature)