RFR: 8263476: NMT: Stack guard pages should not be marked as committed

[Johan Sjölen]

On Thu, 31 Jul 2025 10:36:59 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Use reserved (instead of committed) memory for stack-guard-pages on linux like systems.
> 
> `os::must_commit_stack_guard_pages` uses `commit` in its name, but `commit` usually has specific meanings in OS memory context. The actual question the caller is asking is whether the caller needs to do some preparation work before marking the guard-pages as inaccessible. To avoid confusion, I changed it to "allocate". Other suggestions are welcome.
> 
> Test: tier1-3

src/hotspot/os/linux/os_linux.cpp line 3455:

> 3453: 
> 3454:     if (stack_extent < (uintptr_t)addr + size) {
> 3455:       ::munmap((void*)stack_extent, (uintptr_t)(addr + size - stack_extent));

Could you explain this, is it fixing a pre-existing bug as well?

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PR Review Comment: https://git.openjdk.org/jdk/pull/26571#discussion_r2251354077