Commit 646b67d5 authored by David Hildenbrand's avatar David Hildenbrand Committed by Andrew Morton
Browse files

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: default avatarDavid Hildenbrand <david@redhat.com>
Acked-by: default avatarSeongJae Park <sj@kernel.org>
Reviewed-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 0bf2edf0

mm/memremap.c

+3 −0
Original line number Diff line number Diff line
@@ -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: