panic: Most recently used by tty

cpuid = 1
time = 1557487558
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe00272cc690
vpanic() at vpanic+0x1e0/frame 0xfffffe00272cc6f0
panic() at panic+0x43/frame 0xfffffe00272cc750
mtrash_ctor() at mtrash_ctor+0xed/frame 0xfffffe00272cc790
uma_zalloc_arg() at uma_zalloc_arg+0x1036/frame 0xfffffe00272cc840
malloc() at malloc+0xe1/frame 0xfffffe00272cc8b0
tty_alloc_mutex() at tty_alloc_mutex+0x22c/frame 0xfffffe00272cc8e0
pts_alloc() at pts_alloc+0x179/frame 0xfffffe00272cc930
sys_posix_openpt() at sys_posix_openpt+0x94/frame 0xfffffe00272cc970
ia32_syscall() at ia32_syscall+0x452/frame 0xfffffe00272ccab0
int0x80_syscall_common() at int0x80_syscall_common+0x9c/frame 0xa
KDB: enter: panic
[ thread pid 3846 tid 101055 ]
Stopped at      kdb_enter+0x6a: movq    $0,kdb_why