On Fri, 14 Aug 2026 07:32:55 GMT, Ashay Rane <[email protected]> wrote:
>> Prior to this patch, the `StackYellowPages` and `StackRedPages` >> influenced the total reserved stack memory, but they didn't change the >> minimum stack size specified as required by HotSpot to Windows. This >> patch adds the call to `SetThreadStackGuarantee()` to set the minimum >> stack size. >> >> The key change here is that the argument to `SetThreadStackGuarantee()` >> is set to one less than the total number of yellow pages. The one less >> page is because Windows uses a guard page (access to which tells Windows >> to commit more stack pages); in the terminal case, we want the guard >> page to coincide with the top-most yellow stack page, thus leaving all >> except one yellow page available as the stack size. >> >> Importantly, however, we do not use the red page count as the argument >> to `SetThreadStackGurantee()`, since the red stack pages are unavailable >> for handling recoverable overflows. The red page count impacts the >> _total reserved_ stack size, just not the _minimum_ stack size. Still, >> forcing the red stack page count to be included into the computation of >> the argument to `SetThreadStackGurantee()` causes HotSpot to fail with >> the assertion `assert(!in_vm) failed: Undersized StackShadowPages`, >> since Windows is unable to commit more stack pages due to the minimum >> stack size now being larger than just the yellow page count minus one. >> >> The accompanying test passes zero to `SetThreadStackGuarantee()` to >> probe the current minimum stack size, which we then compare against the >> expected size based on the yellow page count. The same test fails >> without this patch on both Windows/x64 and on Windows/ARM64. >> >> Validated this patch by running through all tier 1, 2, and 3 HotSpot >> jtreg tests on Windows/x64 and Windows/ARM64 in FastDebug config. >> >> --------- >> - [x] I confirm that I make this contribution in accordance with the >> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). > > Ashay Rane has updated the pull request incrementally with one additional > commit since the last revision: > > Skip compilation of libTestWindowsStackPages.c on non-Windows platforms > > Also fix typo in variable name (`uload_requested` -> `ulong_requested`). I'm not quite following this change, but I am not a Windows programmer. The doc for `SetThreadStackGuarantee` states: > Sets the minimum size of the stack associated with the calling thread or > fiber that will be available during any stack overflow exceptions. that seems a different thing to "minimum stack size specified as required by HotSpot to Windows". Further, the docs state: > If the function is successful, the application can handle possible > EXCEPTION_STACK_OVERFLOW exceptions using [structured exception > handling](https://learn.microsoft.com/en-us/windows/desktop/Debug/structured-exception-handling). > To resume execution after handling a stack overflow, you must perform > certain recovery steps. If you are using the Microsoft C/C++ compiler, call > the _resetstkoflw function. but we don't use `_resetstkoflw` AFAICS. ?? ------------- PR Comment: https://git.openjdk.org/jdk/pull/32365#issuecomment-5322803415
