This occurs w/ 2.5 device-mapper; add_disk() is called (w/ a possibly
invalid gendisk).  add_disk() calls register_disk(), which constructs
the device struct (gendisk::disk_dev).  First, the bus_id field is
initialized, and then device_add() is called.  However, device_add()
does no initialization of the device struct.  So, since the
gendisk::disk_dev::parent list is NULL, the gendisk::disk_dev::node
field is never initialized.  Later on in device_add(), if an error has
occurred, list_del_init(&dev->node) is called; dev->node is {NULL,NULL},
and an oops occurs.

Instead of calling device_add(), my patch makes register_disk() call
device_register().  This appear to do the same thing as device_add(),
but initializes the device struct before calling device_add().



-- 
It's not denial.  I'm just selective about the reality I accept.
	-- Bill Watterson