From: David Hildenbrand Date: Mon, 1 Sep 2025 15:03:28 +0000 (+0200) Subject: mm/memremap: reject unreasonable folio/compound page sizes in memremap_pages() X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=9881a56badbe75bcca940636bde5ca4263178a70;p=users%2Fjedix%2Flinux-maple.git mm/memremap: reject unreasonable folio/compound page sizes in memremap_pages() 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. Link: https://lkml.kernel.org/r/20250901150359.867252-8-david@redhat.com Signed-off-by: David Hildenbrand Acked-by: SeongJae Park Reviewed-by: Lorenzo Stoakes Reviewed-by: Liam R. Howlett Signed-off-by: Andrew Morton --- diff --git a/mm/memremap.c b/mm/memremap.c index b0ce0d8254bd..a2d4bb88f64b 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: