Re: [PATCH v3 1/3] mm/huge_memory: don't ignore queried cachemode in vmf_insert_pfn_pud()

[Oscar Salvador]

On Fri, Jun 13, 2025 at 11:27:00AM +0200, David Hildenbrand wrote:
> We setup the cache mode but ... don't forward the updated pgprot to
> insert_pfn_pud().
> 
> Only a problem on x86-64 PAT when mapping PFNs using PUDs that
> require a special cachemode.
> 
> Fix it by using the proper pgprot where the cachemode was setup.
> 
> It is unclear in which configurations we would get the cachemode wrong:
> through vfio seems possible. Getting cachemodes wrong is usually ... bad.
> As the fix is easy, let's backport it to stable.
> 
> Identified by code inspection.
> 
> Fixes: 7b806d229ef1 ("mm: remove vmf_insert_pfn_xxx_prot() for huge page-table entries")
> Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
> Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Tested-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>

Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>


-- 
Oscar Salvador
SUSE Labs