panic: mtx_lock() of destroyed mutex @ /syzkaller/managers/i386/kernel/sys/kern/sys_socket.c:309
cpuid = 1
time = 1560006257
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe0020f445f0
vpanic() at vpanic+0x1e0/frame 0xfffffe0020f44650
panic() at panic+0x43/frame 0xfffffe0020f446b0
__mtx_lock_flags() at __mtx_lock_flags+0x1e2/frame 0xfffffe0020f44710
soo_stat() at soo_stat+0x9c/frame 0xfffffe0020f44750
kern_fstat() at kern_fstat+0xe9/frame 0xfffffe0020f447a0
freebsd32_fstat() at freebsd32_fstat+0x2b/frame 0xfffffe0020f44970
ia32_syscall() at ia32_syscall+0x452/frame 0xfffffe0020f44ab0
int0x80_syscall_common() at int0x80_syscall_common+0x9c/frame 0x814255a
KDB: enter: panic
[ thread pid 1173 tid 100716 ]
Stopped at      kdb_enter+0x6a: movq    $0,kdb_why