Re: [PATCH 1/3] mm/hugetlb_cma: fix incorrect hugetlb_cma_size assignment on malformed input

[Oscar Salvador (SUSE)]

On Wed, Oct 28, 2026 at 07:33:17PM +0800, Kaitao Cheng wrote:
> From: Kaitao Cheng <chengkaitao@xxxxxxxxxx>
> 
> When hugetlb_cma contains a global size after node-specific entries,
> cmdline_parse_hugetlb_cma() enters the global branch and reparses the
> original parameter string. For hugetlb_cma=1:2G,4G, this interprets the
> initial node ID as a one-byte global size and clears the 2 GiB reservation
> recorded for node 1.
> 
> Global and node-specific formats cannot be mixed. Return -EINVAL when a
> global entry follows a node-specific entry, before updating any settings.
> This preserves the valid prefix, so the example retains node 1's 2 GiB
> reservation and reports the malformed option.
> 
> Fixes: 38e719ab2673 ("hugetlb: support node specified when using cma for gigantic hugepages")
> Closes: https://sashiko.dev/#/bug/linux-10f40d3e-3feb-4622-9da8-1fedecb2d0e2
> Signed-off-by: Kaitao Cheng <chengkaitao@xxxxxxxxxx>

Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>

> ---
>  mm/hugetlb_cma.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/hugetlb_cma.c b/mm/hugetlb_cma.c
> index 95fd2d190f0d..8e6b20341fc4 100644
> --- a/mm/hugetlb_cma.c
> +++ b/mm/hugetlb_cma.c
> @@ -167,6 +167,9 @@ static int __init cmdline_parse_hugetlb_cma(char *p)
>  		} else {
>  			char *next;
>  
> +			if (s != p)
> +				return -EINVAL;
> +
>  			tmp = memparse(p, &next);
>  			if (*next == '%') {
>  				if (tmp > 100) {
> -- 
> 2.53.0
> 

-- 
Oscar Salvador
SUSE Labs