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7974c23853
Three mm paths outside the fault handler gate on the uffd PTE bit today: khugepaged (skip collapse on ranges carrying markers), rmap (cap unmap batching), and GUP (force a fault through gup_can_follow_protnone). Extend each to treat VM_UFFD_RWP the same as VM_UFFD_WP; otherwise per-PTE RWP state is silently destroyed or bypassed. khugepaged: try_collapse_pte_mapped_thp() and file_backed_vma_is_retractable() already refuse to collapse or retract page tables on ranges carrying the uffd PTE bit. Broaden the VMA predicate from userfaultfd_wp() to userfaultfd_protected() so VM_UFFD_RWP ranges get the same protection. hpage_collapse_scan_pmd() needs no change — its existing pte_uffd() check already catches an RWP PTE because it carries the uffd bit. rmap: folio_unmap_pte_batch() caps batching at 1 for VM_UFFD_RWP so the restore path handles each PTE with its own marker. GUP: gup_can_follow_protnone() forces a fault on VM_UFFD_RWP VMAs regardless of FOLL_HONOR_NUMA_FAULT. RWP uses protnone as an access-tracking marker, not for NUMA hinting, so any GUP — read or write — must go through the userfaultfd fault path. Link: https://lore.kernel.org/20260708111417.173443-9-kirill@shutemov.name Signed-off-by: Kiryl Shutsemau <kas@kernel.org> Assisted-by: Claude:claude-opus-4-6 Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Reviewed-by: Lorenzo Stoakes <ljs@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Hildenbrand <david@kernel.org> Cc: James Houghton <jthoughton@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Liam Howlett <liam@infradead.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Xu <peterx@redhat.com> Cc: Sean Christopherson <seanjc@google.com> Cc: SeongJae Park <sj@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
3157 lines
92 KiB
3157 lines
92 KiB