Re: [PATCH 1/2] mm, cma: fix 32-bit warning

[Frank van der Linden]

On Mon, Feb 24, 2025 at 6:11 AM Arnd Bergmann <arnd@xxxxxxxxxx> wrote:
>
> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> clang warns about certain always-true conditions, like this one on 32-bit
> builds:
>
> mm/cma.c:420:13: error: result of comparison of constant 4294967296 with expression of type 'phys_addr_t' (aka 'unsigned int') is always true [-Werror,-Wtautological-constant-out-of-range-compare]
>   420 |                 if (start < SZ_4G)
>       |                     ~~~~~ ^ ~~~~~
>
> Replace this one with an equivalent expression that does not cause a warning.
>
> Fixes: 4765deffa0f7 ("mm, cma: support multiple contiguous ranges, if requested")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
>  mm/cma.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/cma.c b/mm/cma.c
> index 34a4df29af72..ef0206c0f16d 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -417,7 +417,7 @@ int __init cma_declare_contiguous_multi(phys_addr_t total_size,
>          * Create a list of ranges above 4G, largest range first.
>          */
>         for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &start, &end, NULL) {
> -               if (start < SZ_4G)
> +               if (upper_32_bits(start) == 0)
>                         continue;
>
>                 start = ALIGN(start, align);
> --
> 2.39.5
>

Thanks for fixing these nits in my patch series - which, btw, needs
more reviews, if anyone's reading this - please :)

Reviewed-by: Frank van der Linden <fvdl@xxxxxxxxxx>