From: Andrew Morton <akpm@osdl.org>

modprobe snd_serial_u16550 -> splat.

Bisection indicates that this oops is triggered by
gregkh-driver-sound-device.patch.

snd_serial_probe() never got to call snd_card_register(), so card->dev is
NULL.

snd_serial_probe() calls snd_card_free(card) on the error path and
snd_card_do_free() does device_del(card->dev) which oopses over the null
pointer it got.  

Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@novell.com>
Cc: Jaroslav Kysela <perex@suse.cz>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 sound/core/init.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff -puN sound/core/init.c~fix-gregkh-driver-sound-device sound/core/init.c
--- a/sound/core/init.c~fix-gregkh-driver-sound-device
+++ a/sound/core/init.c
@@ -361,7 +361,8 @@ static int snd_card_do_free(struct snd_c
 		snd_printk(KERN_WARNING "unable to free card info\n");
 		/* Not fatal error */
 	}
-	device_unregister(card->dev);
+	if (card->dev)
+		device_unregister(card->dev);
 	kfree(card);
 	return 0;
 }
_