I face the same issue as described previously by John Wiegley. After
several hours (sometimes even less than an hour), emacs freezes completely
without the option to recover it.
A backtrace also leads to lisp_align_free:

#0  0x000000000055aa0e in lisp_align_free ()
#1  0x000000000055acd9 in sweep_floats ()
#2  0x00000000005603ac in garbage_collect ()
#3  0x00000000005607e7 in Fgarbage_collect ()
...

This is especially cumbersome since I am running EXWM and have to therefore
recover my session in a tty by restarting my desktop manager.

I will add a timer to run the garbage collector every few (5) seconds so I
can hopefully track which event changes the state in a way that leads it to
the observed freezing behavior.

I report back back if I find out anything new. In the meanwhile, I am happy
for any suggestions on how to debug this issue.

-- 

Moritz Schäfer* <http://www.bsse.ethz.ch>*