Comment 50 for bug 1242321

I have been having what seems like this issue with both LaCie and Seagate external drives when connected to USB 3 ports.

I just had connections to a server freeze and found this message when I went to the physical display (I can share a low quality image of the full screen if that helps):
[309540.436290] BUG: unable to handle kernel NULL pointer dereference at 00000...0000f0
[309540.436313] IP: [<ffff...>] _raw_spin_lock_irq_save+0x1f/0x60
...
[309540.533342] Kernel panic - not syncing: Fatal exception in interrupt
[309540.533366] Kernel Offset: 0x0 from 0xff[... hard to count characters]
[309540.533389] drm_kms_helper: panic occurred, switching back to text console

I have encountered the general issue of USB hard dive in USB 3 port freezing with three different devices running Ubuntu 14.04 over the last few months. The devices are:
1. a Dell laptop that came shipped with Windows that I installed Ubuntu on (not running very well, so I did not think anything of it)
2. a Dell Precision M3800 that came shipped with Ubuntu 14.04 - not sure exact revision when bug presented because I learned never to plug USB drives into USB 3 ports on the laptop, but today it has Ubuntu 14.04.3 LTS
3. just now, I caused a kernel panic on a Lenovo ThinkServer that has Ubuntu 14.04.2 LTS - at this point I thought I should log this. Additional version info is:
  Linux version 3.16.0-50-generic (buildd@lgw01-03) (gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #67~14.04.1-Ubuntu SMP Fri Oct 2 22:07:51 UTC 2015 (Ubuntu 3.16.0-50.67~14.04.1-generic 3.16.7-ckt16)

Note: the symptom for #1 and #2 was that plugging a drive into a USB 3 port caused the computer to 'freeze' - not much useful

Finally, things work fine with all three computers iff I am careful to use only the USB 2 ports with the LaCie or with the Seagate drives.