## Summary

We see a Segmentation Fault when repeatedly switching focus between graphical elements on s390x Linux (zLinux).

This only happens if the JIT is turned on.

## Minimal Testcase

I'm attaching a minimal testcase which reproduces the issue 100% of the time.

You will need to "export DISPLAY=:<display_int>" before the test will work. X11-forwarding is fine, as long as the JVM is running on an s390x machine.

Note that if you run this test with the JIT turned off (-Xint) then the error does not occur.

## Details

If you switch focus between two graphical elements (e.g. JToggleButton) a few dozen times (44-ish) we see a Segmentation Fault with no further information.

This is seen in builds as far back as jdk-17.0.13+1, but does not seem to occur in jdk-17.0.12+7.

This issue is also seen on JDK21 and 24, but not JDK11.

I've seen this across many zLinux machines, both RHEL and Ubuntu. I don't have access to any machines that this does not occur on.