RFR: 8256155: Allow multiple large page sizes to be used on Linux [v32]

[Stefan Johansson]

On Fri, 7 May 2021 16:16:22 GMT, Marcus G K Williams <mgkwill at openjdk.org> wrote:

>> Change the meaning of LargePageSizeInBytes to be the maximum large page size the JVM may use (not the only one). A default value of zero will mean to allow the JVM use large page sizes up to the system's default large page size.
>
> Marcus G K Williams has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 53 commits:
> 
>  - Remove reserve_memory_special_huge_tlbfs mods except assert
>    
>    Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
>  - Merge branch 'master' into update_hlp
>  - Merge branch 'master' into update_hlp
>  - Remove extranous vm_page_size check
>    
>    Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
>  - kstefanj review
>    
>    Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
>  - Set LargePageSizeInBytes to largepage upper limit
>    
>    Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
>  - Merge branch 'master' into update_hlp
>  - Fix merge
>    
>    Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
>  - Merge branch 'master' into update_hlp
>  - Merge branch 'master' into update_hlp
>  - ... and 43 more: https://git.openjdk.java.net/jdk/compare/0790e601...7368e7d4

While doing some manual testing I found a problem when setting `LargePageSizeInBytes=1g`, but without having any 1g pages configured. In that case, we will turn off `UseLargePages` even if there are 2m pages configured. 

Not sure if we should address this as part of this change or as a follow up, but I think the `hugetlbfs_sanity_check(...)` should check that at least one of the supported large pages are configured, not just the one set as the maximum large page size.

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PR: https://git.openjdk.java.net/jdk/pull/1153