On Thu, Aug 28, 2025 at 12:01:11AM +0200, David Hildenbrand wrote:
> Let's reject unreasonable folio sizes early, where we can still fail.
> We'll add sanity checks to prepare_compound_head/prepare_compound_page
> next.
>
> Is there a way to configure a system such that unreasonable folio sizes
> would be possible? It would already be rather questionable.
>
> If so, we'd probably want to bail out earlier, where we can avoid a
> WARN and just report a proper error message that indicates where
> something went wrong such that we messed up.
>
> Acked-by: SeongJae Park <sj@xxxxxxxxxx>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
LGTM, so:
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
> ---
> mm/memremap.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/mm/memremap.c b/mm/memremap.c
> index b0ce0d8254bd8..a2d4bb88f64b6 100644
> --- a/mm/memremap.c
> +++ b/mm/memremap.c
> @@ -275,6 +275,9 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
>
> if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
> return ERR_PTR(-EINVAL);
> + if (WARN_ONCE(pgmap->vmemmap_shift > MAX_FOLIO_ORDER,
> + "requested folio size unsupported\n"))
> + return ERR_PTR(-EINVAL);
>
> switch (pgmap->type) {
> case MEMORY_DEVICE_PRIVATE:
> --
> 2.50.1
>
