We have been having a graphical bug occur for a while now but it's been very difficult to consistently replicate it in order to track down what's happening. We are using Oculus's branch of the UE 4.20.3 engine.
When the bug happens the visuals go black and the application drops to around 5 FPS when looking at the OVRMetrics Tool. Just recently I was able to get a logcat file of it happening so I was able to see what could be causing the problem. When looking at the logcat file I am able to find the point where the bug happens because it starts consistently outputting:
W Adreno-GSL: <sharedmem_gpuobj_alloc:2706>: sharedmem_gpumem_alloc: mmap failed errno 12 Out of memory
E Adreno-GSL: <gsl_memory_alloc_pure:2270>: GSL MEM ERROR: kgsl_sharedmem_alloc ioctl failed.
I've looked above where those lines start outputting and nothing seems to stick out as unusual so I'm not sure where to go from here to further track down what is happening and how to fix it. If anyone has had a similar bug and been able to track down the cause please let me know what steps were used.
It has also happened when we have been testing on Rift on PC, and if it happens in the Editor we can switch into Unlit mode with F2 and we no longer have a black screen. If we switch back into Lit mode with F3 the black screen returns.