panic: Lock ACPI PCI link not exclusively locked

Rebuilt 6.0 kernel tonight, panics at boot:

pci_link0: <ACPI PCI Link LNKB> irq 6 on acpi0
panic: Lock ACPI PCI link not exclusively locked _at_ /a/portbuild/i386/src-client/sys/dev/acpica/acpi_pci_link.c:153

KDB: enter: panic
[thread pid 0 tid 0 ]
Stopped at      kdb_enter+0x32: leal    0(%esi),%esi
db>
db> tr
Tracing pid 0 tid 0 td 0xc07b8260
kdb_enter(c07551c4,c07ba540,c07558db,c0c20a7c,c07b8260) at kdb_enter+0x32
panic(c07558db,c0740d53,c0740d88,99,c0c20b00) at panic+0x14d
_sx_assert(c07b4a60,4,c0740d88,99,c1a2e9c0) at _sx_assert+0xfe
link_add_crs(c1a2e9c0,c0c20b00,c0c20ac8,2c,c1a2e9c0) at link_add_crs+0x35
AcpiWalkResources(c1950900,c073db16,c047e620,c0c20b00,c195c980) at AcpiWalkResources+0x8d
acpi_pci_link_attach(c1a28380,c19bd04c,c077a96c,c0756dc5,0) at acpi_pci_link_attach+0x251
device_attach(c1a28380,c0475100,c0c20b78,c0c20b80,0) at device_attach+0x2c9
prt_attach_devices(c1a08800,c195c400,c195c980,c195c400,c1a0f994) at prt_attach_devices+0xe6
prt_walk_table(c195c400,c0771297,0,c0c20bcc,0) at prt_walk_table+0x3c
acpi_pcib_attach(c195c400,c1a0f994,0,c0c20c04,c0473fb7,c0764021,c1945970,c077a96c,c19494a0) at acpi_pcib_attach+0xe4
acpi_pcib_acpi_attach(c195c400,c19b104c,c077a96c,c0756dc5,0) at acpi_pcib_acpi_attach+0xf9
device_attach(c195c400,1fefffff,c0c20cbc,c0476474,c195c980) at device_attach+0x2c9
bus_generic_attach(c195c980,100000,1fefffff,c1a0f9e8,100000) at bus_generic_attach+0x18
acpi_attach(c195c980,c19ca04c,c077a96c,c0756dc5,0) at acpi_attach+0x7b4
device_attach(c195c980,c195ca00,c0c20d18,c070d6da,c195ca00) at device_attach+0x2c9
bus_generic_attach(c195ca00,c195ca4c,c0c20d54,c0574679,c195ca00) at bus_generic_attach+0x18
nexus_attach(c195ca00,c19e084c,c077a96c,c0756dc5,0) at nexus_attach+0x1a
device_attach(c195ca00,c07a4190,c0c20d78,c06fff08,c19ac180) at device_attach+0x2c9
root_bus_configure(c19ac180,c077305f,0,c0c20d98,c052ed66) at root_bus_configure+0x19
configure(0,0,c0777508,c1ec00,c1e000) at configure+0x28
mi_startup() at mi_startup+0xd6
begin() at begin+0x2c

Kris