On Mon, Aug 11 2025, Mike Rapoport wrote:
> From: "Mike Rapoport (Microsoft)" <r...@kernel.org>
>
> Parsing of kho_scratch parameter treats zero size as an invalid value,
> although it should be fine for user to request zero sized scratch area
> for some types if scratch memory, when for example there is no need to
> create scratch area in the low memory.
Can the system boot with 0 per-node memory? If not, then perhaps we
should only allow lowmem scratch to be zero?
>
> Treat zero as a valid value for a scratch area size but reject
> kho_scratch parameter that defines no scratch memory at all.
>
> Signed-off-by: Mike Rapoport (Microsoft) <r...@kernel.org>
> ---
> kernel/kexec_handover.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c
> index e49743ae52c5..c6ac5a5e51cb 100644
> --- a/kernel/kexec_handover.c
> +++ b/kernel/kexec_handover.c
> @@ -385,6 +385,7 @@ static int __init kho_parse_scratch_size(char *p)
> {
> size_t len;
> unsigned long sizes[3];
> + size_t total_size = 0;
> int i;
>
> if (!p)
> @@ -421,11 +422,15 @@ static int __init kho_parse_scratch_size(char *p)
> }
>
> sizes[i] = memparse(p, &endp);
> - if (!sizes[i] || endp == p)
> + if (endp == p)
> return -EINVAL;
> p = endp;
> + total_size += sizes[i];
> }
>
> + if (!total_size)
> + return -EINVAL;
> +
Looks good. BTW, unrelated to this patch, but should we also check that
p == '\0' here to make sure the whole argument was consumed?
> scratch_size_lowmem = sizes[0];
> scratch_size_global = sizes[1];
> scratch_size_pernode = sizes[2];
--
Regards,
Pratyush Yadav
