Re: [PATCH 2/2] mm/hugetlb: pass correct order_per_bit to cma_declare_contiguous_nid

[Andrew Morton]

On Thu,  4 Apr 2024 16:25:15 +0000 Frank van der Linden <fvdl@xxxxxxxxxx> wrote:

> The hugetlb_cma code passes 0 in the order_per_bit argument to
> cma_declare_contiguous_nid (the alignment, computed using the
> page order, is correctly passed in).
> 
> This causes a bit in the cma allocation bitmap to always represent
> a 4k page, making the bitmaps potentially very large, and slower.
> 
> So, correctly pass in the order instead.

Ditto.  Should we backport this?   Can we somewhat quantify "potentially very",
and understand under what circumstances this might occur?