panic: kernel diagnostic assertion "dupe == NULL" failed: file "/syzkaller/managers/main/kernel/sys/uvm/uvm_page.c", line 144
Stopped at      db_enter+0x1c:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*290228  99985      0           0          0    0  syz-executor.5
db_enter() at db_enter+0x1c sys/arch/amd64/amd64/db_interface.c:437
panic(ffffffff827895c7) at panic+0x165 sys/kern/subr_prf.c:198
__assert(ffffffff82805f0d,ffffffff827ae263,90,ffffffff8275cef7) at __assert+0x29 sys/kern/subr_prf.c:157
uvm_pagealloc_pg(fffffd80062a3e80,fffffd807b839058,1d011000,0) at uvm_pagealloc_pg+0x427 uvm_pageinsert sys/uvm/uvm_page.c:138 [inline]
uvm_pagealloc_pg(fffffd80062a3e80,fffffd807b839058,1d011000,0) at uvm_pagealloc_pg+0x427 sys/uvm/uvm_page.c:709
uvm_pagealloc(fffffd807b839058,1d011000,0,3) at uvm_pagealloc+0x1ec sys/uvm/uvm_page.c:917
pmap_get_ptp(fffffd807b839028,740472021000) at pmap_get_ptp+0x18d sys/arch/amd64/amd64/pmap.c:1209
pmap_enter(fffffd807b839028,740472021000,7b1e9000,1,20) at pmap_enter+0x29d sys/arch/amd64/amd64/pmap.c:2716
uvm_fault_upper_lookup(ffff80002e870db0,ffff80002e870de8,ffff80002e870cb0,ffff80002e870d30) at uvm_fault_upper_lookup+0x2a1 sys/uvm/uvm_fault.c:895
uvm_fault(fffffd80637f9470,740472022000,0,1) at uvm_fault+0x109 sys/uvm/uvm_fault.c:605
upageflttrap(ffff80002e870f30,740472022630) at upageflttrap+0x80 sys/arch/amd64/amd64/trap.c:188
usertrap(ffff80002e870f30) at usertrap+0x20d sys/arch/amd64/amd64/trap.c:436
recall_trap() at recall_trap+0x8
end of kernel
end trace frame: 0x740472022660, 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.