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Sashiko AI review found 1 potential issue to consider: - [Low] mm/huge_memory: inaccurate Fixes trailer for insert_pmd() and insert_pud() -- commit b401d2d30ea8d00390aed1659aa84d49600aa4d3 Author: Eliav Farber > mm/huge_memory: don't warn when a page table blocks a huge pfn insert > > insert_pmd() and insert_pud() treat a non-empty entry at their own level > as a leaf and compare its PFN against the one being inserted. A page > table installed by a concurrent order-0 fault also makes the entry > non-empty, and pmd_pfn()/pud_pfn() then report the PFN of that table, > which never matches. insert_pmd() warns unless the entry is the huge > zero PMD, and insert_pud() warns on any mismatch. > > A VM_PFNMAP mapping with both ->fault and ->huge_fault can produce the > mixed orders: an order-0 fault installs a page table over an address > while a concurrent huge fault on the same address reaches insert_pmd(). > Changing an mm's THP policy while another thread faults the same PMD, > for example with prctl(PR_SET_THP_DISABLE), is enough to do it. > > Compare the PFN only for a leaf entry. A page table is not an error, so > take the existing out_unlock path, which returns VM_FAULT_NOPAGE and > lets the access refault onto the smaller entry. > > Fixes: f9e54c3a2f5b ("vfio/pci: implement huge_fault support") > Signed-off-by: Eliav Farber > Reviewed-by: Jose A. Perez de Azpillaga [Severity: Low] In insert_pmd() and insert_pud(), the pmd_pfn() and pud_pfn() comparisons and their WARN_ON_ONCE() calls only run when write is true. Commit f9e54c3a2f5b ("vfio/pci: implement huge_fault support") always passes write =3D false to vmf_insert_pfn_pmd() and vmf_insert_pfn_pud(), so it cannot reach this warning. Should the Fixes: tag reference c6f3c5ee40c1 ("mm/huge_memory.c: fix modifying of page protection by insert_pfn_pmd()"), which added these checks to mm/huge_memory.c? --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261112051440.1614= 0-1-farbere@amazon.com?part=3D3