Bug #125739 for Linux-Epoll: Segmentation fault in weak_set call during global destruction

As discussed in IRC - since this commit: https://github.com/Leont/linux-epoll/commit/244a90de900779e1952c7d3cf2f23e269f2ef598 I see periodic segfaults in global destruction, example stacktrace: #0 0x00000000004b4dcc in Perl_av_delete () #1 0x00007ffff4504fc1 in weak_set () from .../5.26.1/x86_64-linux/auto/Linux/Epoll/Epoll.so #2 0x000000000049f4ab in Perl_mg_set () #3 0x00000000004d4074 in Perl_sv_kill_backrefs () #4 0x00000000004a2d5d in Perl_magic_killbackrefs () #5 0x00000000004c2914 in S_sv_unmagicext_flags.part.10 () #6 0x00000000004c2a5d in Perl_sv_unmagic () #7 0x00000000004c1b78 in Perl_sv_clear () #8 0x00000000004c2422 in Perl_sv_free2 () #9 0x0000000000470815 in Perl_cv_undef_flags () #10 0x00000000004c1ba8 in Perl_sv_clear () #11 0x00000000004c2422 in Perl_sv_free2 () #12 0x000000000049f025 in S_mg_free_struct () #13 0x000000000049f9d3 in Perl_mg_free () #14 0x00000000004c1b80 in Perl_sv_clear () #15 0x00000000004c2422 in Perl_sv_free2 () #16 0x000000000049f025 in S_mg_free_struct () #17 0x000000000049f9d3 in Perl_mg_free () #18 0x00000000004c1b80 in Perl_sv_clear () #19 0x00000000004c2422 in Perl_sv_free2 () #20 0x00000000004c06d7 in S_visit () #21 0x00000000004c277c in Perl_sv_clean_objs () #22 0x00000000004400bf in perl_destruct () #23 0x000000000041ff54 in main () The rest of the commits in 0.014 are fine - after reverting just that one change, everything is stable again. Will try to put together a test case - my current code is IO::Async-based and doesn't trigger the failure reliably enough. thanks, Tom