uvm_fault(0xffffffff839d8080, 0xffff800028c04300, 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
ffs_write(ffff80003c8ff1e0) at ffs_write+0xb9a sys/ufs/ffs/ffs_vnops.c:401
VOP_WRITE(fffffd807d8dda20,ffff80003c8ff278,23,fffffd8007ffd618) at VOP_WRITE+0x101 sys/kern/vfs_vops.c:245
vn_rdwr(1,fffffd807d8dda20,ffff80003c8ff3b0,40,0,1,f23e4f5bc787b2a7,0,1008,40) at vn_rdwr+0x12d sys/kern/vfs_vnops.c:330
acct_process(ffff80002a778fa0) at acct_process+0x7a2 sys/kern/kern_acct.c:245
exit1(ffff80002a778fa0,0,0,1) at exit1+0x5c4 sys/kern/kern_exit.c:228
sys_exit(ffff80002a778fa0,ffff80003c8ff5e0,ffff80003c8ff530) at sys_exit+0x1a sys/kern/kern_exit.c:-1
syscall(ffff80003c8ff5e0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c8ff5e0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7f319cf69540, count: 6
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: uvm_fault(0xffffffff839d8080, 0xffff800028c04300, 0, 2) -> d
ddb> trace
memset() at memset+0x52
ffs_write(ffff80003c8ff1e0) at ffs_write+0xb9a sys/ufs/ffs/ffs_vnops.c:401
VOP_WRITE(fffffd807d8dda20,ffff80003c8ff278,23,fffffd8007ffd618) at VOP_WRITE+0x101 sys/kern/vfs_vops.c:245
vn_rdwr(1,fffffd807d8dda20,ffff80003c8ff3b0,40,0,1,f23e4f5bc787b2a7,0,1008,40) at vn_rdwr+0x12d sys/kern/vfs_vnops.c:330
acct_process(ffff80002a778fa0) at acct_process+0x7a2 sys/kern/kern_acct.c:245
exit1(ffff80002a778fa0,0,0,1) at exit1+0x5c4 sys/kern/kern_exit.c:228
sys_exit(ffff80002a778fa0,ffff80003c8ff5e0,ffff80003c8ff530) at sys_exit+0x1a sys/kern/kern_exit.c:-1
syscall(ffff80003c8ff5e0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c8ff5e0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7f319cf69540, count: -9
ddb> show registers
rdi               0xffff800028c04300
rsi                                0
rbp               0xffff80003c8ff100
rbx                           0x2300    __ALIGN_SIZE+0x1300
rdx                                0
rcx                             0xa0
rax                                0
r8                             0x500
r9                0xffff80003c8ff060
r10               0x1f33a50ad527efc5
r11               0xffff800028c04300
r12                           0x2300    __ALIGN_SIZE+0x1300
r13                           0x2800    __ALIGN_SIZE+0x1800
r14               0xfffffd807d8dda20
r15                              0x1
rip               0xffffffff832e8b82    memset+0x52
cs                               0x8
rflags                       0x10206    __ALIGN_SIZE+0xf206
rsp               0xffff80003c8feef8
ss                                 0
memset+0x52:    repe stosq      %es:(%rdi)
ddb>