Created attachment 142792 [details]
gbg backtrace with mesa debug symbols
Xwayland(1.20.3) SIGSEGV on startup with mesa 18.2.6
gdb back traces from the core file attached.
Created attachment 142793 [details]
gbg backtrace without mesa debug symbols
Running Alpine Linux (musl libc)
Would you be able to wrap Xwayland into valgrind and attach the traces?
That would help to figure out what memory was freed.
Using the patch from here: https://git.alpinelinux.org/cgit/aports/commit/?id=ff8996cea00e39d93c869434e263268eab704591
with 18.2.6 solves the issue for me