https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81021
--- Comment #21 from Martin Liška <marxin at gcc dot gnu.org> --- > The code uses user-level threads (makecontext/setcontext etc). It annotates > the new stack during the switch, see for example > https://github.com/scylladb/seastar/blob/master/core/thread.cc#L66. > Supposedly it's correct, but perhaps something is missing. Then it should be fine. Well, the patch you send just workaround the problem. I will dig in.