panic: kernel diagnostic assertion "dupe == NULL" failed: file "/syzkaller/managers/main/kernel/sys/uvm/uvm_page.c", line 144
Stopped at      db_enter+0x18:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*250653  49165      0         0x2          0    0  syz-executor.4
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:440
panic(ffffffff825609f3) at panic+0x161 sys/kern/subr_prf.c:202
__assert(ffffffff825d34b0,ffffffff82587c97,90,ffffffff8253c4e0) at __assert+0x25 sys/kern/subr_prf.c:161
uvm_pagealloc_pg(fffffd80066dbd00,fffffd806a900888,d964000,0) at uvm_pagealloc_pg+0x427 uvm_pageinsert sys/uvm/uvm_page.c:138 [inline]
uvm_pagealloc_pg(fffffd80066dbd00,fffffd806a900888,d964000,0) at uvm_pagealloc_pg+0x427 sys/uvm/uvm_page.c:710
uvm_pagealloc(fffffd806a900888,d964000,0,3) at uvm_pagealloc+0x1e8 sys/uvm/uvm_page.c:918
pmap_get_ptp(fffffd806a900878,1b2c921000) at pmap_get_ptp+0x18d sys/arch/amd64/amd64/pmap.c:1183
pmap_enter(fffffd806a900878,1b2c921000,67021000,3,20) at pmap_enter+0x2a0
uvm_fault_lower_lookup(ffff80002e7dae20,ffff80002e7dae58,ffff80002e7dada0) at uvm_fault_lower_lookup+0x263 sys/uvm/uvm_fault.c:1183
uvm_fault_lower(ffff80002e7dae20,ffff80002e7dae58,ffff80002e7dada0,0) at uvm_fault_lower+0x5f sys/uvm/uvm_fault.c:1218
uvm_fault(fffffd806c3e5230,1b2c920000,0,1) at uvm_fault+0x21d
upageflttrap(ffff80002e7daf90,1b2c920000) at upageflttrap+0x79 sys/arch/amd64/amd64/trap.c:181
usertrap(ffff80002e7daf90) at usertrap+0x198 sys/arch/amd64/amd64/trap.c:403
recall_trap() at recall_trap+0x8
end of kernel
end trace frame: 0x7f7ffffe9820, count: 2
https://www.openbsd.org/ddb.html describes the minimum info required in bug
reports.  Insufficient info makes it difficult to find and fix bugs.