I cannot be 100% sure, but we have ample evidence suggesting we're experiencing this same crash in production.

We have a big system that mixes Cython and pure-python coroutines, and in one version we started seeing segfaults that strongly hint at this root cause.

Adding pure-python indirections (that keep the arguments alive, I'd wager), fixes those segfaults.

I cannot share the codebase (and in any case it's too big, and the crash is too difficult to reproduce in isolation, without real traffic), but I'd add my +1 on applying this fix.

We're currently testing to try and reproduce the segfaults on 2.7.13, after that I'll try jdemeyer's patch and report the results.