Backport d583d360a6 into 5.12 stable

Hello.

I'd like to nominate d583d360a6 ("psi: Fix psi state corruption when schedule() races with cgroup move") for 5.12 stable tree.

Recently, I've hit this:

``` kernel: psi: inconsistent task state! task=2667:clementine cpu=21 psi_flags=0 clear=1 set=0 ```

and after that PSI IO went crazy high. That seems to match the symptoms described in the commit message.

Thanks.