Re: [PATCH v3 1/2] x86/mm: Handle alloc failure in phys_*_init()

[Dave Hansen]

On 6/10/25 03:16, Em Sharnoff wrote:
> +		if (!pmd)
> +			return (unsigned long)ERR_PTR(-ENOMEM);

All of this casting isn't great to look at. Just about every line of
code that this patch touches also introduces has a cast.

Could you please find a way to reduce the number of casts?

> +		/*
> +		 * We might have IS_ERR(paddr_last) if allocation failed, but we should
> +		 * still update pud before bailing, so that subsequent retries can pick
> +		 * up on progress (here and in phys_pmd_init) without leaking pmd.
> +		 */

Please write everything in imperative voice. No "we's", please.

> -	for (i = 0; i < nr_range; i++)
> +	for (i = 0; i < nr_range; i++) {
>  		ret = kernel_physical_mapping_init(mr[i].start, mr[i].end,
>  						   mr[i].page_size_mask,
>  						   prot);
> +		if (IS_ERR((void *)ret))
> +			return ret;
> +	}

Are there any _actual_ users of 'paddr_last'? I see a lot of setting it
and passing it around, but I _think_ this is the only place it actually
gets used. Here, the fact that it's an address doesn't even matter.