uvm_fault(0xffffffff839e5648, 0xffff800020a92000, 0, 2) -> d
kernel: page fault trap, code=2
Stopped at      memset+0x52:    repe stosq      %es:(%rdi)
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
memset() at memset+0x52
VOP_WRITE(fffffd806cb6adc0,ffff80002a293f30,0,fffffd80097fd1a0) at VOP_WRITE+0x101 sys/kern/vfs_vops.c:245
uvn_io(fffffd806e805738,ffff80002a2940b0,d,39,1) at uvn_io+0x498 sys/uvm/uvm_vnode.c:1232
uvm_pager_put(fffffd806e805738,fffffd800883fef0,ffff80002a294150,ffff80002a294174,39,0,c8bbdb52797e5b5e) at uvm_pager_put+0x10a sys/uvm/uvm_pager.c:505
uvn_flush(fffffd806e805738,0,0,19) at uvn_flush+0x690 sys/uvm/uvm_vnode.c:705
uvn_detach(fffffd806e805738) at uvn_detach+0xcf sys/uvm/uvm_vnode.c:344
uvm_unmap_detach(ffff80002a294280,0) at uvm_unmap_detach+0x15e sys/uvm/uvm_map.c:1370
uvm_map_teardown(fffffd806e8541f8) at uvm_map_teardown+0x360 sys/uvm/uvm_map.c:2536
exit1(ffff8000ffffd230,43,0,1) at exit1+0x6fc sys/kern/kern_exit.c:260
sys_exit(ffff8000ffffd230,ffff80002a294450,ffff80002a2943a0) at sys_exit+0x1a sys/kern/kern_exit.c:-1
syscall(ffff80002a294450) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a294450) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7bc7d67fffe0, count: 3
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{0}> 
ddb{0}> set $lines = 0
ddb{0}> set $maxwidth = 0
ddb{0}> show panic
*cpu0: uvm_fault(0xffffffff839e5648, 0xffff800020a92000, 0, 2) -> d
ddb{0}> trace
memset() at memset+0x52
VOP_WRITE(fffffd806cb6adc0,ffff80002a293f30,0,fffffd80097fd1a0) at VOP_WRITE+0x101 sys/kern/vfs_vops.c:245
uvn_io(fffffd806e805738,ffff80002a2940b0,d,39,1) at uvn_io+0x498 sys/uvm/uvm_vnode.c:1232
uvm_pager_put(fffffd806e805738,fffffd800883fef0,ffff80002a294150,ffff80002a294174,39,0,c8bbdb52797e5b5e) at uvm_pager_put+0x10a sys/uvm/uvm_pager.c:505
uvn_flush(fffffd806e805738,0,0,19) at uvn_flush+0x690 sys/uvm/uvm_vnode.c:705
uvn_detach(fffffd806e805738) at uvn_detach+0xcf sys/uvm/uvm_vnode.c:344
uvm_unmap_detach(ffff80002a294280,0) at uvm_unmap_detach+0x15e sys/uvm/uvm_map.c:1370
uvm_map_teardown(fffffd806e8541f8) at uvm_map_teardown+0x360 sys/uvm/uvm_map.c:2536
exit1(ffff8000ffffd230,43,0,1) at exit1+0x6fc sys/kern/kern_exit.c:260
sys_exit(ffff8000ffffd230,ffff80002a294450,ffff80002a2943a0) at sys_exit+0x1a sys/kern/kern_exit.c:-1
syscall(ffff80002a294450) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a294450) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7bc7d67fffe0, count: -12
ddb{0}>