latest amd64 XEN3_DOMU panics at boot

[Jeff Rizzo <riz%tastylime.net@localhost>]

I assume this is because of the rmind-uvmplock branch merge, but the 
latest amd64 domU kernel downloaded from the releng cluster panics at boot:

root on xbd0a dumps on xbd0b
mountroot: trying smbfs...
mountroot: trying ntfs...
mountroot: trying nfs...
mountroot: trying msdos...
mountroot: trying lfs...
mountroot: trying ext2fs...
mountroot: trying ffs...
root file system type: ffs
init: copying out path `/sbin/init' 11
panic: kernel diagnostic assertion "(pte & PG_G) == 0 || pm == 
pmap_kernel()" failed: file 
"/home/builds/ab/HEAD/src/sys/arch/x86/x86/pmap_tlb.c", line 212
fatal breakpoint trap in supervisor mode
trap type 1 code 0 rip ffffffff801314cd cs e030 rflags 246 cr2  
ffffa00024020000 cpl 0 rsp ffffa00023e90490
Stopped in pid 1.1 (init) at    netbsd:breakpoint+0x5:  leave
breakpoint() at netbsd:breakpoint+0x5
panic() at netbsd:panic+0x28c
kern_assert() at netbsd:kern_assert+0x2d
pmap_tlb_shootdown() at netbsd:pmap_tlb_shootdown+0x17b
pmap_remove_pte() at netbsd:pmap_remove_pte+0x21e
pmap_remove() at netbsd:pmap_remove+0x3a5
uvm_unmap_remove() at netbsd:uvm_unmap_remove+0x171
uvm_unmap1() at netbsd:uvm_unmap1+0x4e
uvmspace_exec() at netbsd:uvmspace_exec+0xb4
execve1() at netbsd:execve1+0x825
start_init() at netbsd:start_init+0x209
ds          1280
es          96d1
fs          470
gs          18c1
rdi         0
rsi         d
rbp         ffffa00023e90490
rbx         ffffa00023e904a0
rdx         0
rcx         8
rax         1
r8          ffffffff805c0280    cpu_info_primary
r9          0
r10         ffffa00023e903b0
r11         1
r12         104
r13         ffffffff80461280    copyright+0x3ef00
r14         7f7ffffff000
r15         ffffa00000e232e8
rip         ffffffff801314cd    breakpoint+0x5
cs          e030
rflags      246
rsp         ffffa00023e90490
ss          e02b
netbsd:breakpoint+0x5:  leave
db>

...i386 PAE kernel seems OK.

+j