[ 1374.0891533] panic: kernel diagnostic assertion "pmap->pm_obj[i].uo_npages == 0" failed: file "/syzkaller/managers/netbsd/kernel/sys/arch/x86/x86/pmap.c", line 2464 
[ 1374.0991863] cpu1: Begin traceback...
[ 1374.1091862] vpanic() at netbsd:vpanic+0x214
[ 1374.1192043] _GLOBAL__sub_D_65535_0_cpu_configure() at netbsd:_GLOBAL__sub_D_65535_0_cpu_configure
[ 1374.1292212] pmap_destroy() at netbsd:pmap_destroy+0x40d
[ 1374.1392364] pmap_pp_remove() at netbsd:pmap_pp_remove+0x876
[ 1374.1592697] uvm_anon_dispose() at netbsd:uvm_anon_dispose+0x179
[ 1374.1692841] uvm_anon_freelst() at netbsd:uvm_anon_freelst+0x48
[ 1374.1792974] amap_wipeout() at netbsd:amap_wipeout+0x237
[ 1374.1893126] uvm_unmap_detach() at netbsd:uvm_unmap_detach+0x8b
[ 1374.1993285] uvmspace_free() at netbsd:uvmspace_free+0x200
[ 1374.2093451] exit1() at netbsd:exit1+0x39d
[ 1374.2193632] sys_exit() at netbsd:sys_exit+0x6c
[ 1374.2293749] syscall() at netbsd:syscall+0x32e
[ 1374.2393903] --- syscall (number 1) ---
[ 1374.2393903] 7999324fe47a:
[ 1374.2393903] cpu1: End traceback...

[ 1374.2494050] dumping to dev 4,1 (offset=0, size=0): not possible
[ 1374.2494050] rebooting...
SeaBIOS (version 1.8.2-20190122_225043-google)
Total RAM Size = 0x00000001e0000000 = 7680 MiB
CPUs found: 2     Max CPUs supported: 2
found virtio-scsi at 0:3
virtio-scsi vendor='Google' product='PersistentDisk' rev='1' type=0 removable=0
virtio-scsi blksize=512 sectors=4194304 = 2048 MiB
drive 0x000f29c0: PCHS=0/0/0 translation=lba LCHS=520/128/63 s=4194304
Booting from Hard Disk 0...

>> NetBSD/x86 BIOS Boot, Revision 5.10 (Tue Jul 17 14:59:51 UTC 2018) (from NetBSD 8.0)
>> Memory: 639/3144640 k

     1. Boot normally
     2. Boot single user
     3. Disable ACPI
     4. Disable ACPI and SMP
     5. Drop to boot prompt