[jdk15u-dev] RFR: 8274435: EXCEPTION_ACCESS_VIOLATION in BFSClosure::closure_impl

[Ekaterina Vergizova]

Fix Request (15u)
I'd like to backport this fix to 15u. It prevents JVM crashes during JFR path to GC roots calculation.
The patch applies cleanly, tested with jdk/jfr.

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Commit messages:
 - Backport c05dc268acaf87236f30cf700ea3ac778e3b20e5

Changes: https://git.openjdk.java.net/jdk15u-dev/pull/109/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk15u-dev&pr=109&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274435
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk15u-dev/pull/109.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk15u-dev pull/109/head:pull/109

PR: https://git.openjdk.java.net/jdk15u-dev/pull/109