On Mon, 27 Apr 2026 12:45:49 +0100 "Kiryl Shutsemau (Meta)" <[email protected]> wrote:
> 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. I agree. It can be useful for general access monitoring. I'm also slowly but continuously working [1] to use that for DAMON. > > 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. I think this is a good change for making the infrastructure available for uffd. I believe this can also be useful for making it further available for general access monitoring purposes. I hope this to be landed on the mainline sooner than later. Thank you for doing this, Kiryl! > > Signed-off-by: Kiryl Shutsemau (Meta) <[email protected]> > Assisted-by: Claude:claude-opus-4-6 Acked-by: SeongJae Park <[email protected]> [1] https://lore.kernel.org/linux-mm/[email protected]/ Thanks, SJ [...]
