[bwlang]

without this fix i was seeing GPU runs crashing with errors like these:

• "illegal memory access" errors inside RELION's GPU allocator (custom_allocator.cuh)
• segfaults in CudaCustomAllocator::_free
• an out-of-memory report asking for 564 TB
• "No orientation was found as better than any other"
• NVIDIA Xid 31 and Xid 13 ("Out Of Range Address") in the kernel log, on two different GPU

with this fix it's working.

[biochem-fan]

Thank you very much. I merged an earlier PR #1375 that had the same fix.

Your PR contains another fix about memory alignment.
Could you please provide the detail? Does it cause crash, or inefficiency?

[bwlang]

I've rebased...

This PR is now a "correctness" fix... i didn't test it separately from the #1375 parallel fix though so I'm not sure of often it bites in practice.

Allocations above 16MB will round incorrectly I think, leading to a too small allocation and potential writes past the end of the allocated region if the entire block is used.

[biochem-fan]

OK, I understood the logic. float32 has 9 exponent bits and 23 fraction bits and 16 MB = 2^(23 + 1). So beyond 16 MB some lower bits are rounded. I agree with your point.

I merge this. Thank you very much.