RFR: 8263236: runtime/os/TestTracePageSizes.java fails on old kernels [v4]

[Stefan Johansson]

On Thu, 6 May 2021 10:46:15 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> See the bug report for details. On some kernels, the madvise hint is not reflected in `/proc/smaps`. Instead, we can use a secondary evidence and read `AnonHugePages`.
>> 
>> Additional testing:
>>  - [x] Test with kernel 5.4.0 (still passes)
>>  - [x] Test with kernel 4.9.0 (used to fail, now passes)
>
> Aleksey Shipilev has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - No tabs
>  - Just ignore on older kernels

Looks good to me. The `isLinux()` check should not be needed since we require this to only run on Linux. But it won't hurt and makes it more clear so I'm good with it.

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Marked as reviewed by sjohanss (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/3415