[$] Linux 5.12's very bad, double ungood day

The -rc kernels released by Linus Torvalds exist for a reason: after 10,000or so changes flow into the kernel over a two-week merge window, there willsurely be some bugs in need of squashing. The -rc kernels provide anopportunity for wider testing after all those patches have beenintegrated. Most of the time, -rc kernels (even the initial -rc1 releases)are surprisingly safe to run. Occasionally, though, something goes wrong,giving early testers reason to reconsider their life choices. The 5.12-rc1kernel, as it turns out, was one of those.