[Intel-gfx] System freeze apparently due to GPU memory exhaustion - why?

[Adam Nielsen]

Hi all,

I'm an end user and I'm having problems which I believe are ultimately
caused by an issue with the Intel kernel driver.

When I am running programs that use a lot of images (e.g. GIMP, Firefox
with YouTube and Google Maps) then after a short while my whole machine
will grind to a halt, to the point where even my audio buffers don't
get updated so I hear the same 500ms of audio repeated in a loop until
the system comes back to life again.

Typically the system will stop responding from anywhere between 30
seconds to a minute, and usually it returns to service after the kernel
OOM killer has ended a process - typically Firefox as it uses the most
system memory.

Of course it's not a system OOM problem, because the system has 16GB of
RAM and the problem still happens even if less than 4GB is in use.

Looking at dmesg, the problem always starts with a message like this:

  Purging GPU memory, 69632 bytes freed, 48553984 bytes still pinned.

Since system memory is fine, I can only assume this means that there is
some limit on the amount of memory the video driver can access, and it
has reached that limit.

Here is the top of the backtrace, if it's relevant:

  Call Trace:
   [<ffffffff812c0dc9>] dump_stack+0x4b/0x72
   [<ffffffff811d6682>] dump_header+0x87/0x21e
   [<ffffffffa0646c01>] ? i915_gem_shrinker_oom+0x1a1/0x200 [i915]
   [<ffffffff8116214b>] oom_kill_process+0x34b/0x3b0
   [<ffffffff8116241f>] out_of_memory+0x21f/0x490
   [<ffffffff811680f8>] __alloc_pages_nodemask+0x8c8/0x960
   [<ffffffff811683ab>] alloc_kmem_pages_node+0x7b/0x150

Can anyone shed any light on what's happening here?  Is there a limit
to how much video memory the system can access?  I thought that was
done away with once AGP disappeared but perhaps not.

Is there any way to alleviate the problems this issue produces?  It's
very annoying to be zooming around in Google Maps one moment and then
dumped back to the console the next because the kernel killed X11.

My system is an Intel DH87MC w/ i7-4770K, kernel 4.3.3.  Three
monitors, DVI + HDMI + DisplayPort, total res 4960x1600.

Many thanks,
Adam.