[$] Revisiting stable-kernel regressions

Stable-kernel updates are, unsurprisingly, supposed to be stable; that iswhy the first of the rulesfor stable-kernel patches requires them to be "obviously correctand tested". Even so, for nearly as long as the kernel community has been producing stable updatereleases, said community has also been complaining about regressions thatmake their way intothose releases. Back in 2016, LWN did someanalysis that showed the presence of regressions in stable releases, thoughat a rate that many saw as being low enough. Since then, the volume ofpatches showing up in stable releases has grown considerably, so perhapsthe time has come to see what the situation with regressions is with current stable kernels.