Re: [RFC v2 1/4] cma: Enforce non-zero pageblock_order during cma_init_reserved_mem()

[David Hildenbrand]

On 11.10.24 09:23, Ritesh Harjani (IBM) wrote:
> cma_init_reserved_mem() checks base and size alignment with
> CMA_MIN_ALIGNMENT_BYTES. However, some users might call this during
> early boot when pageblock_order is 0. That means if base and size does
> not have pageblock_order alignment, it can cause functional failures
> during cma activate area.
>
> So let's enforce pageblock_order to be non-zero during
> cma_init_reserved_mem().
>
> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
> ---
>   mm/cma.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
>
> diff --git a/mm/cma.c b/mm/cma.c
> index 3e9724716bad..36d753e7a0bf 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -182,6 +182,15 @@ int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
>   	if (!size || !memblock_is_region_reserved(base, size))
>   		return -EINVAL;
>   
> +	/*
> +	 * CMA uses CMA_MIN_ALIGNMENT_BYTES as alignment requirement which
> +	 * needs pageblock_order to be initialized. Let's enforce it.
> +	 */
> +	if (!pageblock_order) {
> +		pr_err("pageblock_order not yet initialized. Called during early boot?\n");
> +		return -EINVAL;
> +	}
> +
>   	/* ensure minimal alignment required by mm core */
>   	if (!IS_ALIGNED(base | size, CMA_MIN_ALIGNMENT_BYTES))
>   		return -EINVAL;


Acked-by: David Hildenbrand <david@xxxxxxxxxx>

--
Cheers,

David / dhildenb