syzbot

uvm_fault(fffffd806c65a558,a4b861a000,0,2) at uvm_fault+0x159 sys/uvm/uvm_fault.c:605
upageflttrap(ffff80002a132b30,a4b861aae0) at upageflttrap+0xa9 sys/arch/amd64/amd64/trap.c:188
usertrap(ffff80002a132b30) at usertrap+0x2d8 sys/arch/amd64/amd64/trap.c:436
recall_trap() at recall_trap+0x8
end of kernel
end trace frame: 0x70a9eb1fb160, count: -13
ddb{0}> machine ddbcpu 1
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
ddb{1}> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:437
witness_checkorder(fffffd8064d650a0,9,0) at witness_checkorder+0x1047
rw_enter(fffffd8064d65090,1) at rw_enter+0x122
rrw_enter(fffffd8064d65090,1) at rrw_enter+0xbe sys/kern/kern_rwlock.c:464
VOP_LOCK(fffffd806003cb48,2001) at VOP_LOCK+0xa6 sys/kern/vfs_vops.c:524
vn_lock(fffffd806003cb48,2001) at vn_lock+0xa4 sys/kern/vfs_vnops.c:564
vfs_lookup(ffff800037276048) at vfs_lookup+0x109 sys/kern/vfs_lookup.c:418
namei(ffff800037276048) at namei+0x7aa sys/kern/vfs_lookup.c:250
unp_connect(ffff8000012fe2e8,fffffd806bc6cf00,ffff8000ffffdbe8) at unp_connect+0x27d sys/kern/uipc_usrreq.c:868
uipc_dgram_send(ffff8000012fe2e8,fffffd805fd84900,fffffd806bc6cf00,0) at uipc_dgram_send+0x131 sys/kern/uipc_usrreq.c:607
sosend(ffff8000012fe2e8,fffffd806bc6cf00,ffff8000372762d8,0,0,8) at sosend+0xa40
sendit(ffff8000ffffdbe8,3,ffff800037276450,8,ffff800037276510) at sendit+0x721 sys/kern/uipc_syscalls.c:786
sys_sendmsg(ffff8000ffffdbe8,ffff8000372765c0,ffff800037276510) at sys_sendmsg+0x246 sys/kern/uipc_syscalls.c:604
syscall(ffff8000372765c0) at syscall+0xbb6 mi_syscall sys/sys/syscall_mi.h:178 [inline]
syscall(ffff8000372765c0) at syscall+0xbb6 sys/arch/amd64/amd64/trap.c:577
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xe7a2dfd9780, count: -15