RFR: 8263476: Use reserved memory for stack guard pages [v3]

[Thomas Stuefe]

On Wed, 6 Aug 2025 02:06:21 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> src/hotspot/os/linux/os_linux.cpp line 3478:
>> 
>>> 3476:       ::munmap((void*)stack_extent, (uintptr_t)(addr + size - stack_extent));
>>> 3477:     }
>>> 3478:     return os::pd_attempt_reserve_memory_at(addr, size, !ExecMem) != nullptr;
>> 
>> This patch indeed goes beyond my original intention. IIRC,  my intention was to replace `os::commit()` with `::mprotect()` to set protection on stack guard pages.
>
> @zhengyu123 I don't understand your comment - we already do use `mprotect` on the (committed) stack guard pages. ??

I am confused, too.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26571#discussion_r2256444975