wkspace failed allocations with heap protection enabled

[Joel Sherrill]

This appears to be a bad side-effect of the way the deferred free is
implemented
when the memory protection/fence is enabled. This is turned on by enabling
rtems debug.

I'd recommend filing a ticket and assigning it to Sebastian for a real fix.

In the meantime, see if building RTEMS without debug enabled helps.

--joel

On Wed, Apr 13, 2022 at 4:30 AM Matthew J Fletcher <amimjf at gmail.com> wrote:

> Hi,
>
> Investigating the "Total number of failed allocations:" from the
> wkspace cmd i see that;
>
>     /* Statistics */
>     ++stats->failed_allocs;
>
> Are incremented when _Heap_Allocate_aligned_with_boundary fails, however it
> seems this will routinely fail due to;
>
> _Heap_Protection_free_all_delayed_blocks seemingly on purpose creating an
> impossibly large allocation.
>
>     uintptr_t large = 0
>       - (uintptr_t) HEAP_BLOCK_HEADER_SIZE
>       - (uintptr_t) HEAP_ALLOC_BONUS
>       - (uintptr_t) 1;
>
>     void *p = _Heap_Allocate( heap, large );
>
> This makes it difficult to place a breakpoint on failed_allocs to
> investigate true low memory situations with heap protection enabled.
>
>
> regards
> ---
> Matthew J Fletcher
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