Re: [PATCH] mm: Throttle shrinkers harder

[Dave Hansen <dave.hansen@intel.com>]

On 04/24/2014 08:39 AM, Chris Wilson wrote:
> On Thu, Apr 24, 2014 at 08:21:58AM -0700, Dave Hansen wrote:
>> Is it possible that there's still a get_page() reference that's holding
>> those pages in place from the graphics code?
> 
> Not from i915.ko. The last resort of our shrinker is to drop all page
> refs held by the GPU, which is invoked if we are asked to free memory
> and we have no inactive objects left.

How sure are we that this was performed before the OOM?

Also, forgive me for being an idiot wrt the way graphics work, but are
there any good candidates that you can think of that could be holding a
reference?  I've honestly never seen an OOM like this.

Somewhat rhetorical question for the mm folks on cc: should we be
sticking the pages on which you're holding a reference on our
unreclaimable list?

> If we could get a callback for the oom report, I could dump some details
> about what the GPU is holding onto. That seems like a useful extension to
> add to the shrinkers.

There's a register_oom_notifier().  Is that sufficient for your use, or
is there something additional that would help?