RFR: 8229147: Linux os::create_thread() overcounts guardpage size with newer glibc (>=2.27)

[David Holmes]

On Fri, 21 Apr 2023 13:52:59 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> We can now detect whether glibc includes the guard pages as part of the requested stack size or not, and so only need to make adjustments when glibc requires it.
>> 
>> The intent was to use a local variable as the "flag" but unfortunately it is also needed in os_posix.cpp so I had to make it part of the os::Linux API.
>> 
>> See bug report (and related) for details.
>> 
>> Testing:
>>   - Manually checked log output for stack sizes and boundaries on systems with and without the glibc fix. (Again see JBS issue)
>>   -  Tiers 1-3 sanity
>> Thanks
>
> src/hotspot/os/linux/os_linux.cpp line 823:
> 
>> 821: 
>> 822: // In glibc versions prior to 2.27 the guard size mechanism
>> 823: // was not implemented properly. The posix standard requires adding
> 
> "POSIX"

Fixed

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PR Review Comment: https://git.openjdk.org/jdk/pull/13571#discussion_r1177218033