CVE-2026-64416 mm: swap_cgroup: fix NULL deref in lookup_swap_cgroup_id on swapless host

In the Linux kernel, the following vulnerability has been resolved: mm: swapcgroup: fix NULL deref in lookupswapcgroupid on swapless host lookupswapcgroupid passes swapcgroupctrltype.map to swapcgroupidlookup without checking that the type was ever registered via swapcgroupswapon. On a swapless...