wgpu: Segfault/hang related to gpu-alloc (macOS 11, metal)

After updating to latest version of wgpu-rs, I’ve gotten a consistent crash issue in my code. If I roll back to the version of wgpu-rs before gpu-alloc replaced gfx-memory, then the app runs fine. The crash isn’t immediate, but does happen consistently after the app renders enough frames.

I’ll see what I can do to reproduce in some smaller codebase, but the problem I’m having now is that I’ve only gotten a segfault once - every other time it just locks up the computer, forcing me to reboot. That’s making it more than a little difficult to track down.

The best I’ve got so far is that it’s happening in queue.rs queue_write_buffer when it calls: stage.memory.write_bytes(&device.raw, 0, data)?; MemoryBlock::write_bytes has some unsafe code calling into gpu-alloc that is presumably where things go bad.