panic: kmmaplk rwlock 0xffffffff83a711c0: enter read deadlock
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff8342d427) at panic+0x1cf sys/kern/subr_prf.c:198
rw_do_enter_read(ffffffff83a711c0,0) at rw_do_enter_read+0x435 sys/kern/kern_rwlock.c:379
uvmfault_lookup(ffff80002a7d2c70,0) at uvmfault_lookup+0x122 sys/uvm/uvm_fault.c:1880
uvm_fault_check(ffff80002a7d2c70,ffff80002a7d2ca8,ffff80002a7d2ce0,0) at uvm_fault_check+0x4f sys/uvm/uvm_fault.c:693
uvm_fault(ffffffff83a710d8,ffff800029ee6000,0,2) at uvm_fault+0xe6 sys/uvm/uvm_fault.c:627
kpageflttrap(ffff80002a7d2e10,ffff800029ee6000) at kpageflttrap+0x2d1 sys/arch/amd64/amd64/trap.c:-1
kerntrap(ffff80002a7d2e10) at kerntrap+0x18a sys/arch/amd64/amd64/trap.c:528
alltraps_kern_meltdown() at alltraps_kern_meltdown+0x7b
kcov_remote_enter(0,ffff80002a79ed10) at kcov_remote_enter+0x122 sys/dev/kcov.c:670
timeout_run(ffffffff83939ea0,ffff80002a736338) at timeout_run+0xdf sys/kern/kern_timeout.c:696
softclock_process_tick_timeout(ffff80002a736338,0) at softclock_process_tick_timeout+0x230 sys/kern/kern_timeout.c:756
softclock(0) at softclock+0x152 sys/kern/kern_timeout.c:788
softintr_dispatch(0) at softintr_dispatch+0xf9 sys/kern/kern_softintr.c:87
end trace frame: 0xffff80002a7d3060, count: 0
https://www.openbsd.org/ddb.html describes the minimum info required in bug
reports.  Insufficient info makes it difficult to find and fix bugs.
ddb> 
ddb> set $lines = 0
ddb> set $maxwidth = 0
ddb> show panic
*cpu0: kmmaplk rwlock 0xffffffff83a711c0: enter read deadlock
ddb>