Endless soft-lockups for compiling workload since next-20200519

[Peter Zijlstra]

On Thu, May 21, 2020 at 02:40:36AM +0200, Frederic Weisbecker wrote:

>                                                        atomic_fetch_or(...., nohz_flags(0))
>     softirq() {                                        #VMEXIT or anything that could stop a CPU for a while
>         run_rebalance_domain() {
>             nohz_idle_balance() {
>                 atomic_andnot(NOHZ_KICK_MASK, nohz_flag(0))

I'm an idiot and didn't have enough wake-up-juice; I missed that andnot
clearing the flag again.

Yes, fun fun fun..