While testing the fix for another bug (7014261: G1: RSet-related failures) I came across this SIGSEGV:

[GC pause (young) 16M->3424K(128M), 0.0123880 secs]
[GC pause (young) 19M->8034K(128M), 0.0221660 secs]
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Unexpected Error
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SIGSEGV (0xb) at pc=0x00000030efa78700, pid=27656, tid=139955669034768

Do you want to debug the problem?

To debug, run 'gdb /proc/27656/exe 27656'; then switch to thread 139955669034768 (0x00007f49f7efe710)
Enter 'yes' to launch gdb automatically (PATH must include gdb)
Otherwise, press RETURN to abort...
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