RFR: 8377368: [REDO] Mixed jstack cannot find function in vDSO

[Kevin Walls]

On Fri, 6 Feb 2026 15:39:13 GMT, Yasumasa Suenaga <ysuenaga at openjdk.org> wrote:

> We fixed mixed jstack failure when the call stack has frame in vDSO like `gettimeofday()` in [JDK-8376269](https://bugs.openjdk.org/browse/JDK-8376269). But it has been backouted due to build error (see [JDK-8377365](https://bugs.openjdk.org/browse/JDK-8377365) for details).
> 
> JDK-8376269 uses `memfd_create` to copy vDSO from coredump to temporal memory, however it cannot be used on older glibc - some CI works on glibc 2.12, it does not have `memfd_create` unfortunately.
> 
> Thus this PR proposes to use `tmpfile()` and `fileno()` to copy vDSO, as alternatives of `memfd_create()`. It works, and passed all serviceability/sa tests on Linux AMD64.
> 
> Changes from JDK-8376269 is https://github.com/openjdk/jdk/commit/0c315303865efe60de54276bbcf2faf174fd1d9b .

Yes this update looks good to me.

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Marked as reviewed by kevinw (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/29610#pullrequestreview-3780395192