RFR: 8253926: Use extra_size correctly in anon_mmap_aligned

[Stefan Johansson]

On Fri, 2 Oct 2020 10:42:50 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> A recent cleanup ([8253638: Cleanup os::reserve_memory and remove MAP_FIXED](https://github.com/openjdk/jdk/pull/357/))
>> got a size mixed up in `anon_mmap_aligned()`. Instead of passing down the calculated `extra_size` to `anon_mmap()` it
>> uses the original size `bytes`.  This resulted in an early crash when using large pages and with this fix the crash
>> goes away.
>
> Marked as reviewed by kbarrett (Reviewer).

Thanks @shipilev and @kimbarrett for reviewing.

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PR: https://git.openjdk.java.net/jdk/pull/479