Re: [PATCH 1/2] mm/cma: drop incorrect alignment check in cma_init_reserved_mem

[Andrew Morton]

On Thu,  4 Apr 2024 16:25:14 +0000 Frank van der Linden <fvdl@xxxxxxxxxx> wrote:

> cma_init_reserved_mem uses IS_ALIGNED to check if the size
> represented by one bit in the cma allocation bitmask is
> aligned with CMA_MIN_ALIGNMENT_BYTES (pageblock size).
> 
> However, this is too strict, as this will fail if
> order_per_bit > pageblock_order, which is a valid configuration.
> 
> We could check IS_ALIGNED both ways, but since both numbers are
> powers of two, no check is needed at all.

What are the userspace visible effects of this bug?