6.16-stable review patch. If anyone has any objections, please let me know.
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From: David Hildenbrand david@redhat.com
commit 09fefdca80aebd1023e827cb0ee174983d829d18 upstream.
Patch series "mm/huge_memory: vmf_insert_folio_*() and vmf_insert_pfn_pud() fixes", v3.
While working on improving vm_normal_page() and friends, I stumbled over this issues: refcounted "normal" folios must not be marked using pmd_special() / pud_special(). Otherwise, we're effectively telling the system that these folios are no "normal", violating the rules we documented for vm_normal_page().
Fortunately, there are not many pmd_special()/pud_special() users yet. So far there doesn't seem to be serious damage.
Tested using the ndctl tests ("ndctl:dax" suite).
This patch (of 3):
We set up 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.
Link: https://lkml.kernel.org/r/20250613092702.1943533-1-david@redhat.com Link: https://lkml.kernel.org/r/20250613092702.1943533-2-david@redhat.com Fixes: 7b806d229ef1 ("mm: remove vmf_insert_pfn_xxx_prot() for huge page-table entries") Signed-off-by: David Hildenbrand david@redhat.com Reviewed-by: Dan Williams dan.j.williams@intel.com Reviewed-by: Lorenzo Stoakes lorenzo.stoakes@oracle.com Reviewed-by: Jason Gunthorpe jgg@nvidia.com Reviewed-by: Oscar Salvador osalvador@suse.de Tested-by: Dan Williams dan.j.williams@intel.com Cc: Alistair Popple apopple@nvidia.com Cc: Baolin Wang baolin.wang@linux.alibaba.com Cc: Dev Jain dev.jain@arm.com Cc: Liam Howlett liam.howlett@oracle.com Cc: Mariano Pache npache@redhat.com Cc: Michal Hocko mhocko@suse.com Cc: Mike Rapoport rppt@kernel.org Cc: Ryan Roberts ryan.roberts@arm.com Cc: Suren Baghdasaryan surenb@google.com Cc: Vlastimil Babka vbabka@suse.cz Cc: Zi Yan ziy@nvidia.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/huge_memory.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)
--- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1516,10 +1516,9 @@ static pud_t maybe_pud_mkwrite(pud_t pud }
static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, - pud_t *pud, pfn_t pfn, bool write) + pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) { struct mm_struct *mm = vma->vm_mm; - pgprot_t prot = vma->vm_page_prot; pud_t entry;
if (!pud_none(*pud)) { @@ -1581,7 +1580,7 @@ vm_fault_t vmf_insert_pfn_pud(struct vm_ pfnmap_setup_cachemode_pfn(pfn_t_to_pfn(pfn), &pgprot);
ptl = pud_lock(vma->vm_mm, vmf->pud); - insert_pfn_pud(vma, addr, vmf->pud, pfn, write); + insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write); spin_unlock(ptl);
return VM_FAULT_NOPAGE; @@ -1625,7 +1624,7 @@ vm_fault_t vmf_insert_folio_pud(struct v add_mm_counter(mm, mm_counter_file(folio), HPAGE_PUD_NR); } insert_pfn_pud(vma, addr, vmf->pud, pfn_to_pfn_t(folio_pfn(folio)), - write); + vma->vm_page_prot, write); spin_unlock(ptl);
return VM_FAULT_NOPAGE;