CVE-2024-40948 mm/page_table_check: fix crash on ZONE_DEVICE

In the Linux kernel, the following vulnerability has been resolved: mm/pagetablecheck: fix crash on ZONEDEVICE Not all pages may apply to pgtable check. One example is ZONEDEVICE pages: they map PFNs directly, and they don't allocate pageext at all even if there's struct page around. One may...