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Kiryl Shutsemau (Meta)
c6f11553c0
Patch series "userfaultfd: working set tracking for VM guest memory", v10. This series adds userfaultfd support for tracking the working set of VM guest memory, so a VMM can identify hot pages and reclaim cold ones to tiered or remote storage. This patch (of 15): pte_protnone() and pmd_protnone() detect present-but-inaccessible page table entries. This capability is useful beyond NUMA balancing -- for example, userfaultfd working set tracking uses protnone PTEs to track page access without unmapping pages. Introduce CONFIG_ARCH_HAS_PTE_PROTNONE to decouple the protnone PTE infrastructure from CONFIG_NUMA_BALANCING. The six architectures that support protnone PTEs (x86_64, arm64, powerpc, s390, riscv, loongarch) now select this option, and CONFIG_NUMA_BALANCING depends on it. No functional change -- the same set of architectures continues to have working protnone support, but the infrastructure is now available independently of NUMA balancing. Link: https://lore.kernel.org/[email protected] Link: https://lore.kernel.org/[email protected] Signed-off-by: Kiryl Shutsemau (Meta) <[email protected]> Assisted-by: Claude:claude-opus-4-6 Acked-by: SeongJae Park <[email protected]> Acked-by: Mike Rapoport (Microsoft) <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: David Hildenbrand <[email protected]> Cc: James Houghton <[email protected]> Cc: Jonathan Corbet <[email protected]> Cc: Liam Howlett <[email protected]> Cc: Lorenzo Stoakes <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Peter Xu <[email protected]> Cc: Sean Christopherson <[email protected]> Cc: Suren Baghdasaryan <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: Zi Yan <[email protected]> Signed-off-by: Andrew Morton <[email protected]>