> This happens at random during boot when loading modules.
 > About half of the time ide-scsi works fine.
 > The system continues to boot after the BUG with /dev/hdc unaccessible.

from mm/slab.c:

1475 if (xchg((unsigned long *)objp, RED_MAGIC1) != RED_MAGIC2)
1476     /* Either write before start, or a double free. */
1477     BUG();

You run an uniprocessor kernel, with slab debugging enabled, and the 
red-zoning test notices a write before the beginning of the buffer 
during scsi_probe_and_add_lun, with ide-scsi.

Andre: Do you know if ide-scsi makes any assumptions about memory 
alignment of the input buffers? With slab debugging disabled, the 
alignment is 32 or 64 bytes, with debugging enabled, it's just 4 byte 
[actually sizeof(void*)] aligned.

Murray, could you apply the attached patch? It dumps the redzone value 
during scsi_probe_and_add_lun. Hopefully this will help to find who 
corrupts the buffers.

--
	Manfred