Re: [PATCH v1 07/36] mm/memremap: reject unreasonable folio/compound page sizes in memremap_pages()
From: Lorenzo Stoakes <hidden>
Date: 2025-08-28 14:40:39
Also in:
dri-devel, intel-gfx, io-uring, kvm, linux-crypto, linux-ide, linux-iommu, linux-kselftest, linux-mips, linux-mm, linux-mmc, linux-riscv, linux-s390, linux-scsi, lkml, netdev, virtualization
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@kernel.org> Signed-off-by: David Hildenbrand <redacted>
LGTM, so: Reviewed-by: Lorenzo Stoakes <redacted>
quoted hunk ↗ jump to hunk
--- 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