Created attachment 717661 [details]
screenshot showing kernel panic stack trace

+++ This bug was initially created as a clone of Bug #1018911 +++

## observation

On DELL Latitude E7250 after waking up the system from STR in the docking
station after some seconds the system freezes and only shows a blinking caps
lock LED, i.e. kernel panic. I assume it can also be reproduced by switching
displays with xrandr and/or also when switching from vt7 with X to vt1 under
these circumstances, i.e. after wakeup from standby. Once so far I managed to
switch to text terminal and observe an OOM message and a stack trace (see
screenshot). As the problem commonly was triggered by switching displays and
the stack trace mentions drm I assume the problem is related to the graphics
driver but because it takes some seconds for the system to crash it might also
be a critical OOM happening.

kdump is enabled, no crash dump was recorded in the filesystem so far. Reason
might be I am running cryptlvm?

## reproducible

For me the procedure which seems to reproduce it consistently is as follows

* put system to STR in the docking station
* wait for system to be in STR
* close lid
* remove from dock
* put it back to dock
* open lid (system starts up)
* call `xrandr --outpxrandr --output eDP1 --primary --auto --output DP1-1
--off; xrandr --output eDP1 --primary --auto --output DP1-1 --auto --left-of
eDP1`
* wait some seconds
* observe the problem (blinking caps lock led, system does not react anymore)


## expected results

last good should be linux 4.4.36, at least I do not recall observing this
problem in before the last kernel update, at least not that often.

Expected: Obviously the kernel should not crash here.


## problem

H1. regression in kernel update
H1.1 4.4.27-2.1 -> 4.4.49-16
H1.2 4.4.36-5.1 -> 4.4.49-16
H1.3 4.4.36-8.1 -> 4.4.49-16
H1.4 4.4.46-11.1 -> 4.4.49-16
H2. regression in graphics driver
H3. OOM since some package update


## further information

The problem might be related to what Anton is observing since 4.4.36 in bug
1018911

BIOS:
[    0.000000] DMI: Dell Inc. Latitude E7250/0TVD2T, BIOS A07 09/01/2015

kernel command line:
[    0.000000] Kernel command line: BOOT_IMAGE=/vmlinuz-4.4.49-16-default
root=/dev/mapper/system-root ro loader=syslinux quiet resume=/dev/system/swap
splash=silent quiet showopts crashkernel=103M,high crashkernel=72M,low

graphics controller:
00:02.0 VGA compatible controller: Intel Corporation Broadwell-U Integrated
Graphics (rev 09)