RFR: 8260262: Use common code in function unmap_shared() in perfMemory_posix.cpp

[Harold Seigel]

On Wed, 4 Aug 2021 17:15:46 GMT, Harold Seigel <hseigel at openjdk.org> wrote:

> Please review this change to use common code in function unmap_shared() in perfMemory_posix.cpp, to fix JDK-8260262.  The change calls munmap() directly to deallocate the memory because functions mmap_create_shared() and mmap_attach_shared() call mmap() directly to allocate the memory.
> 
> The change was tested by running Mach5 tiers 1-2 on Linux, MacOS, and Windows, and Mach5 tiers 3-5 on Linux x64 and MacOS x64.
> 
> Note that testing on AIX is needed.
> 
> Thanks, Harold

Thanks Thomas and Coleen for reviewing this change.

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PR: https://git.openjdk.java.net/jdk/pull/4995