panic: assertion "mp->mnt_refs == 0" failed in mount_drop at /usr/src/sys/kern/vfs_mount.c:402
cpuid = 4
Trace beginning at frame 0xfffff8011828b6e8
mount_drop() at mount_drop+0x5d 0xffffffff806fa56d
mount_drop() at mount_drop+0x5d 0xffffffff806fa56d
sys_fhstatfs() at sys_fhstatfs+0xd4 0xffffffff80707464
sys_xsyscall() at sys_xsyscall+0x89 0xffffffff80bd7039
syscall2() at syscall2+0x11e 0xffffffff80bd6a0e
Debugger("panic")

CPU4 stopping CPUs: 0x0000002f
 stopped
Stopped at      Debugger+0x7c:  movb    $0,0xbdaf09(%rip)
db>