3.8.13 bone66 mmcqd related kernel panic under disk load about linux

[rainforest1155]

Actually, it wasn't entirely correct that I had all the updates for Debian installed. On Aug 30 I updated these packages:
libc-bin libc-dev-bin locales multiarch-support libc6-dev libc6
to 2.13-38+deb7u4
I restarted the system and overnight, the same freeze occurred. I thought of it as coincidence, but then the next night it happened again.
So I rolled the packages back to 2.13-38+deb7u3 which helped that the system wasn't crashing each night, but less frequently again.
Last night I decided to give the 2.13-38+deb7u4 version of the packages another try and the crash happened again over night. Here's the net console log:

[56582.698248] INFO: task mmcqd/0:71 blocked for more than 60 seconds.
[56582.705082] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[56582.713434] mmcqd/0         D c04a09ff     0    71      2 0x00000000
[56582.720398] Kernel panic - not syncing: hung_task: blocked tasks
[56582.726811] [<c001125d>] (unwind_backtrace+0x1/0x98) from [<c049bb93>] (panic+0x5b/0x160)
[56582.735476] [<c049bb93>] (panic+0x5b/0x160) from [<c00724ed>] (watchdog+0x1a1/0x1c8)
[56582.743696] [<c00724ed>] (watchdog+0x1a1/0x1c8) from [<c004485f>] (kthread+0x6b/0x74)
[56582.752021] [<c004485f>] (kthread+0x6b/0x74) from [<c000c7fd>] (ret_from_fork+0x11/0x34)
[56582.760578] drm_kms_helper: panic occurred, switching back to text console 

So for now, I rolled the packages back to deb7u3.

I'd appreciate any suggestions that you can offer.

Sebastian