RFR: 8340401: DcmdMBeanPermissionsTest.java and SystemDumpMapTest.java fail with assert(_stack_base != nullptr) failed: Sanity check [v9]

[David Holmes]

On Fri, 13 Dec 2024 16:35:54 GMT, Simon Tooke <stooke at openjdk.org> wrote:

>> This PR addresses JDK-8340401 by adding a test for a thread with no stack currently assigned.
>
> Simon Tooke has updated the pull request incrementally with one additional commit since the last revision:
> 
>   implement and use new Thread::stack_base_or_null() method

src/hotspot/share/nmt/memMapPrinter.cpp line 175:

> 173:   // kernel. That can happen, e.g., for non-java threads that don't have guard pages.
> 174:   // Therefore we go for the simplest way here and check for intersection between VMA and thread stack.
> 175:   return range_intersects(from, to, (const void*)t->stack_end(), (const void*)t->stack_base_or_null());

Possibly add a comment:

// Note it is possible to encounter a brand new thread that has not yet initialized its stack fields.

src/hotspot/share/runtime/thread.hpp line 528:

> 526:   // Stack overflow support
> 527:   address stack_base() const DEBUG_ONLY(;) NOT_DEBUG({ return _stack_base; })
> 528:   address stack_base_or_null() const   { return _stack_base; }

Suggestion:

  // Needed for code that can query a new thread before the stack has been set.
  address stack_base_or_null() const   { return _stack_base; }

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PR Review Comment: https://git.openjdk.org/jdk/pull/21091#discussion_r1885424091
PR Review Comment: https://git.openjdk.org/jdk/pull/21091#discussion_r1885423635