Four stable kernel updates

The 6.8.3, 6.7.12, 6.6.24, and 6.1.84 stable kernel updates have been
released. Each contains an important set of fixes. Note that 6.7.12 is
the final release for the 6.7.y series, and that branch is now
end-of-life. Users should move to the 6.8.y branch.