Drywall screws snap off when trying to fix squeaky subfloor
It won't likely cause a problem, and it may resolve the squeak. Drywall screws are very hard and somewhat brittle to keep them from stripping during install. For that reason, they're not ideal for your current purposes. 

That said, I'd consider those screws too small. You only have 3/4" remaining after you go through the subfloor (at most). Also, you won't be able to easily remove them later if you need to. 

I'd use 2-1/2" construction (gold) screws from a good manufacturer (cheap screws are cheap) instead.