ACPI related LOR and panic

After upgrading my laptop to -CURRENT as of last Friday I get the LOR
and panic below.  The previous kernel was from Feb. 14th and is fine.

Sleeping on "acsem" with the following non-sleepable locks held:
exclusive sleep mutex ACPI EC lock r = 0 (0xc2eb4db4) locked _at_ /d2/emaste/HEAD/src/sys/modules/acpi/acpi/../../../dev/acpica/acpi_ec.c:323
exclusive sleep mutex acpi subsystem GPE lock r = 0 (0xc2e8db00) locked _at_ /d2/emaste/HEAD/src/sys/modules/acpi/acpi/../../../dev/acpica/Osd/OsdSynch.c:377
KDB: stack backtrace:
db_trace_self_wrapper(c094e32c) at db_trace_self_wrapper+0x25
kdb_backtrace(2,c2e886c0,c2e89360,0,d4f44b88,...) at kdb_backtrace+0x29
witness_warn(5,c2e8d980,c094bc26,c0d4a56b) at witness_warn+0x192
_sleep(c2e8d980,c2e8d980,100,c0d4a56b,0,...) at _sleep+0x42
AcpiOsWaitSemaphore(c2e8d980,1,ffff,c2e8da00,15,...) at AcpiOsWaitSemaphore+0x140
AcpiExSystemWaitSemaphore(c2e8d980,ffff,d4f44c38,c0d1e189,3e8,...) at AcpiExSystemWaitSemaphore+0x41
AcpiEvAcquireGlobalLock(3e8,3e8,c2eb4dd0,d4f44c54,c0d1b8ce,...) at AcpiEvAcquireGlobalLock+0x5e
AcpiExAcquireMutexObject(3e8,c2e8da00,15,0,c2eb4d80,...) at AcpiExAcquireMutexObject+0x6d
AcpiAcquireGlobalLock(3e8,c2eb4dd0,c2e8b06c,9,c2eaca9b,...) at AcpiAcquireGlobalLock+0x2e
EcGpeHandler(c2eb4d80,1,c2eacac0,d4f44cbc,c0d19862,...) at EcGpeHandler+0xfa
AcpiEvGpeDispatch(c2e8b06c,9,1b,1,0,...) at AcpiEvGpeDispatch+0x9b
AcpiEvGpeDetect(c2e790a0,c2eac9c0,d4f44ce4,c06ab63d,c2e790a0,...) at AcpiEvGpeDetect+0xd2
AcpiEvSciXruptHandler(c2e790a0) at AcpiEvSciXruptHandler+0x13
ithread_execute_handlers(c2e886c0,c2d9c000) at ithread_execute_handlers+0x121
ithread_loop(c2e790b0,d4f44d38) at ithread_loop+0x67
fork_exit(c06ab6fc,c2e790b0,d4f44d38) at fork_exit+0xac
fork_trampoline() at fork_trampoline+0x8
--- trap 0, eip = 0, esp = 0xd4f44d70, ebp = 0 ---
panic: Trying sleep, but thread marked as sleeping prohibited

	- Ed