Backporting stack guard fixes from JDK-9 (8169373+8159335+8139864)

[Jan Kratochvil (Azul)]

Hi Thomas,

On Thu, 07 Dec 2023 00:22:34 +0800, Thomas Stüfe wrote:
> are you sure this crash is related to JDK-8169373?

No.


> As far as I remember that bug resulted in threads possibly failing to start
> because the thread stack size specified was too small;
> I don't see how it can cause crashes like the one you describe. Once the
> thread had been started successfully, things should work, no?

The thread crashes still very early - in its glibc startup. As its TLS address
(which is in the top last page of its stack) is unmapped. I expect another
thread could accidentally unmap the pages due to some discrepancy of stack
boundaries calculations between glibc and JVM. JVM was fixing some that stuff
in:
	JDK-8169373: Work around linux NPTL stack guard error

hotspot/src/os/linux/vm/os_linux.cpp:
bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
  if (os::is_primordial_thread()) {
...
    if (stack_extent < (uintptr_t)addr) {
      ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent));


Thanks for hints,
Jan