sched/psi: Fix mistaken CPU pressure indication after corrupted task state bug

Since sched_delayed tasks remain queued even after blocking, the load
balancer can migrate them between runqueues while PSI considers them
to be asleep. As a result, it misreads the migration requeue followed
by a wakeup as a double queue:

  psi: inconsistent task state! task=... cpu=... psi_flags=4 clear=. set=4

First, call psi_enqueue() after p->sched_class->enqueue_task(). A
wakeup will clear p->se.sched_delayed while a migration will not, so
psi can use that flag to tell them apart.

Then teach psi to migrate any "sleep" state when delayed-dequeue tasks
are being migrated.

Delayed-dequeue tasks can be revived by ttwu_runnable(), which will
call down with a new ENQUEUE_DELAYED. Instead of further complicating
the wakeup conditional in enqueue_task(), identify migration contexts
instead and default to wakeup handling for all other cases.

It's not just the warning in dmesg, the task state corruption causes a
permanent CPU pressure indication, which messes with workload/machine
health monitoring.

Debugged-by-and-original-fix-by: K Prateek Nayak <[email protected]>
Fixes: 152e11f6df29 ("sched/fair: Implement delayed dequeue")
Closes: https://lore.kernel.org/lkml/[email protected]/
Closes: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Johannes Weiner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Tested-by: K Prateek Nayak <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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