[PATCH 3/3] malloc: Remove currently broken memory tagging

[Florian Weimer]

* Yury Khrustalev:

> On Fri, May 08, 2026 at 06:29:43PM +0200, Florian Weimer wrote:
>> * Yury Khrustalev:
>> 
>> ...
>>
>> I think this was with glibc-2.39-derived code, so a bit different from
>> the malloc in the current tree.
>> 
>
> The code in malloc.c and arena.c and adjacent files is being changed
> regularly, and memory tagging hasn't been broken all at once. I suppose
> some use cases still work, but overall it's broken because it'd been
> interleaved with core (i.e. target independent) malloc implementation,
> and changes made to it were not carefully validated wrt to restrictions
> imposed by this "embedded" memory tagging code (see for instance comment
> about memory tagging across internal interfaces above the CHUNK_HDR_SZ
> macro in malloc/malloc.c).
>
> Anyway, to avoid it being accidentally broken again, we should decouple
> target independent code from AArch64-specific, and for this we need this
> patch...

I agree that this is the right call at this time.  I found the existing
hooks not particularly useful, either.  We can compare notes later and
see what kind of customization hooks we will need in the future.
Removing the current set of hooks is totally fine with me.

Thanks,
Florian