[PATCH 2.43] malloc: Show hugetlb tunable default in --list-tunables

[Wilco Dijkstra]

Hi Alexander,

> On Thu, 2026-08-13 at 13:52 +0000, Wilco Dijkstra wrote:
>> The backport looks fine - I can do the commit if you don't have write access.
>
> sure, thank you for the quick reaction! (no, I don't have write access)

OK, committed as 7d26579873791748c20d874adb66e877412175dd

> I believe the pages are getting accessed, but the side effect comes on the systems
> which always had
>
> /sys/kernel/mm/transparent_hugepage/enabled: [always] madvise never
>
> so madvise() syscall plays no role for them, but padding does.

If you set THP to [always], you explicitly state that you want hugepages to be used as
much as possible. You will always get hugepages for large allocations or as a result of
background page coalescing. Other allocators are far more aggressive than GLIBC -
this work is reducing these obvious gaps.

Cheers,
Wilco