syzbot

uvm_fault(fffffd807effa898,25e52c52000,0,2) at uvm_fault+0x238
upageflttrap(ffff80002af93b70,25e52c52000) at upageflttrap+0x85 sys/arch/amd64/amd64/trap.c:186
usertrap(ffff80002af93b70) at usertrap+0x204 sys/arch/amd64/amd64/trap.c:438
recall_trap() at recall_trap+0x8
end of kernel
end trace frame: 0x25e00762600, count: -13
ddb{0}> machine ddbcpu 1
Stopped at      db_enter+0x18:  addq    $0x8,%rsp
ddb{1}> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:437
witness_checkorder(fffffd807514d5f8,9,0) at witness_checkorder+0x10b7 witness_debugger sys/kern/subr_witness.c:2502 [inline]
witness_checkorder(fffffd807514d5f8,9,0) at witness_checkorder+0x10b7 sys/kern/subr_witness.c:1105
rw_enter(fffffd807514d5e8,81) at rw_enter+0xd1 sys/kern/kern_rwlock.c:250
rrw_enter(fffffd807514d5e8,81) at rrw_enter+0x8b sys/kern/kern_rwlock.c:465
VOP_LOCK(fffffd805e312370,81) at VOP_LOCK+0x87 sys/kern/vfs_vops.c:518
vn_lock(fffffd805e312370,81) at vn_lock+0x84 sys/kern/vfs_vnops.c:564
uvn_io(fffffd8075695388,ffff8000283758e0,1,23,1) at uvn_io+0x31a sys/uvm/uvm_vnode.c:1263
uvn_put(fffffd8075695388,ffff8000283758e0,1,23) at uvn_put+0xd0 sys/uvm/uvm_vnode.c:926
uvm_pager_put(fffffd8075695388,fffffd8007fb52e0,ffff800028375978,ffff8000283759b8,23,0,7e0491697eb2690f) at uvm_pager_put+0x137 sys/uvm/uvm_pager.c:545
uvn_flush(fffffd8075695388,0,1000,3) at uvn_flush+0x532 sys/uvm/uvm_vnode.c:725
uvm_map_clean(fffffd8069a9e540,20000000,20002000,3) at uvm_map_clean+0x71b sys/uvm/uvm_map.c:4703
syscall(ffff800028375bb0) at syscall+0x555 mi_syscall sys/sys/syscall_mi.h:113 [inline]
syscall(ffff800028375bb0) at syscall+0x555 sys/arch/amd64/amd64/trap.c:626
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xdc6564fccc0, count: -13