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@kernel.org Reviewed-by: Lorenzo Stoakes lorenzo.stoakes@oracle.com Reviewed-by: Liam R. Howlett Liam.Howlett@oracle.com Signed-off-by: David Hildenbrand david@redhat.com --- 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: