On 29.04.24 13:41, Ryan Roberts wrote:
pagemap_scan_pmd_entry() checks if uffd-wp is set on each pte to avoid unnecessary if set. However it was previously checking with `pte_uffd_wp(ptep_get(pte))` without first confirming that the pte was present. It is only valid to call pte_uffd_wp() for present ptes. For swap ptes, pte_swp_uffd_wp() must be called because the uffd-wp bit may be kept in a different position, depending on the arch. This was leading to test failures in the pagemap_ioctl mm selftest, when bringing up uffd-wp support on arm64 due to incorrectly interpretting the uffd-wp status of migration entries. Let's fix this by using the correct check based on pte_present(). While we are at it, let's pass the pte to make_uffd_wp_pte() to avoid the pointless extra ptep_get() which can't be optimized out due to READ_ONCE() on many arches. Closes: https://lore.kernel.org/linux-arm-kernel/ZiuyGXt0XWwRgFh9@x1n/ Fixes: 12f6b01a0bcb ("fs/proc/task_mmu: add fast paths to get/clear PAGE_IS_WRITTEN flag") Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx> ---
Acked-by: David Hildenbrand <david@xxxxxxxxxx> -- Cheers, David / dhildenb
