Re: An oversight in ExecInitAgg for grouping sets

On Mon, 9 Jan 2023 at 22:21, David Rowley <dgrowleyml(at)gmail(dot)com> wrote:
> One extra thing I noticed was that I had to add a new
> VALGRIND_MAKE_MEM_DEFINED in AllocSetAlloc when grabbing an item off
> the freelist. I didn't quite manage to figure out why that's needed as
> when we do AllocSetFree() we don't mark the pfree'd memory with
> NOACCESS, and it also looks like AllocSetReset() sets the keeper
> block's memory to NOACCESS, but that function also clears the
> freelists too, so the freelist chunk is not coming from a recently
> reset context.

It seems I didn't look hard enough for NOACCESS marking. It's in
wipe_mem(). So that explains why the VALGRIND_MAKE_MEM_DEFINED is
required in AllocSetAlloc.

Since this patch really only touches Valgrind macros, I don't really
feel like there's a good reason we can't still do this for v16, but
I'll start another thread to increase visibility to see if anyone else
thinks differently about that.

David