Comment 40 for bug 1640518

From that debian thread:

"Per logs from message #15 on bug #842796:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=842796#15

SIGSEGV on __lll_unlock_elision is a signature (IME with very high
confidence) of an attempt to unlock an already unlocked lock while
running under hardware lock elision.

Well, unlocking an already unlocked lock is a pthreads API rule
violation, and it is going to crash the process on something that
implements hardware lock elision."

So I think we have some pretty good evidence of an application problem. I think that using Paul Clarke's suggestion may be necessary for you to figure out where the double-unlock is occurring. I'm not confident that valgrind will spot this.

We're going to continue trying to reproduce on our side and disable TLE to confirm that this segv goes away. Hard to know if this is related to the original reported problem, of course, but perhaps losing TLE will allow valgrind to find that if it's a separate issue.