RFR: 8324781: runtime/Thread/TestAlwaysPreTouchStacks.java failed with Expected a higher ratio between stack committed and reserved [v9]

[Patrick Zhang]

On Thu, 6 Jun 2024 08:33:57 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> The real issue is a clash with UEK-proprietary flags. Adding proprietary flags is not a good practice. More clashes are waiting to happen, including clashes with the far more dangerous MADV_DOEXEC.

Thanks @tstuefe, agree with you on this point, so having >=5.14 check is a way to protect JVM from accidentally executing unexpected/dangerous ops like MADV_DOEXEC, although the if-cond is not an elegant code snippet to OpenJDK. @limingliu-ampere and I did not have tests (or any downport experiments) on pre-5.14 so we are not sure if a downport support for MADV_POPULATE_WRITE would normally function or practically benefit. 

@stefank @jdksjolen what's your option? 
In the change suggested by @tstuefe , the pretouch function on UEK pre-5.14 would keep the `bug` until https://github.com/oracle/linux-uek/issues/23 gets fixed by UEK, while `-XX:-UseMadvPopulateWrite` will be added to the two test cases so failures will be gone (hidden). Please share your comments, thanks.

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PR Comment: https://git.openjdk.org/jdk/pull/18592#issuecomment-2151788943