ACPI errors

[Filippo Forti]

Hi,

Since about 20 days I randomly get an ACPI error. This is the output
from WITNESS:

Sleeping on "acsem" with the following non-sleepable
locks held:
exclusive sleep mutex acpica subsystem lock r = 0 (0xc235c9c0) locked @
/usr/src/sys/modules/acpi/acpi/../../../dev/acpica/Osd/O
sdSynch.c:360
KDB: stack backtrace:
kdb_backtrace(c09dbe14,e32beb84,1,1,1) at kdb_backtrace+0x2f
witness_warn(5,c235cb40,c08cb115,c0baf5ca,c065b845) at
witness_warn+0x1bb
msleep(c235cb40,c235cb40,100,c0baf5ca,0) at msleep+0x58
AcpiOsWaitSemaphore(c235cb40,1,ffff,8,15) at AcpiOsWaitSemaphore+0x1fb
AcpiUtAcquireMutex(7,1,0,0,0) at AcpiUtAcquireMutex+0x8f
AcpiDisableGpe(0,1c,1,c227a7d1,c239f180) at AcpiDisableGpe+0x23
EcGpeHandler(c239f180,1,0,8,102f) at EcGpeHandler+0x3f
AcpiEvGpeDispatch(c2380f50,1c,c227a7dd,27fa10,4) at
AcpiEvGpeDispatch+0xc4
AcpiEvGpeDetect(c230bc20,0,c230bc20,e32bed14,c064f39e) at
AcpiEvGpeDetect+0x12f
AcpiEvSciXruptHandler(c230bc20,0,c08c8452,256,c0990c60) at
AcpiEvSciXruptHandler+0x2a
ithread_loop(c2279880,e32bed48,c08c8251,30e,c2279880) at
ithread_loop+0x157
fork_exit(c064f247,c2279880,e32bed48) at fork_exit+0xc7
fork_trampoline() at fork_trampoline+0x8
--- trap 0x1, eip = 0, esp = 0xe32bed7c, ebp = 0 ---


The machine is a Dell Inspiron 5100 running -CURRENT and a modified DSDT
taken from acpi.sf.net which used to work fine. 
This is the link to the DSDT 
http://acpi.sourceforge.net/dsdt/tables/Dell/Inspiron_5100/Dell-Inspiron_5100-A26-custom.asl.gz
The error doesn't seem to cause any big problem, as the computer doesn't
panic on it.

Is this somehow dangerous? Please let me know how I can fix/help fixing
this problem

Thanks in advance 
Best regards
Filippo