db{3}> cont
uvm_fault(0xfffffe84365f2d68, 0x0, 1) -> e
fatal page fault in supervisor mode
trap type 6 code 0 rip ffffffff804e2ebb cs 8 rflags 10286 cr2  8 cpl 0 rsp fffffe811f6a3900
kernel: page fault trap, code=0
Stopped in pid 690.71192 (java) at      netbsd:mutex_oncpu+0x22:        movq    1
8(%rbx),%rax
db{3}> bt
mutex_oncpu() at netbsd:mutex_oncpu+0x22
mutex_enter() at netbsd:mutex_enter+0xd7
filt_piperead() at netbsd:filt_piperead+0xb1
kevent1() at netbsd:kevent1+0x63a
sys___kevent50() at netbsd:sys___kevent50+0x33
syscall() at netbsd:syscall+0xc4
db{3}>