sched/core: Dequeue PSI signals for blocked tasks that are delayed

psi_dequeue() in for blocked task expects psi_sched_switch() to clear
the TSK_.*RUNNING PSI flags and set the TSK_IOWAIT flags however
psi_sched_switch() uses "!task_on_rq_queued(prev)" to detect if the task
is blocked or still runnable which is no longer true with DELAY_DEQUEUE
since a blocking task can be left queued on the runqueue.

This can lead to PSI splats similar to:

    psi: inconsistent task state! task=... cpu=... psi_flags=4 clear=0 set=4

when the task is requeued since the TSK_RUNNING flag was not cleared
when the task was blocked.

Explicitly communicate that the task was blocked to psi_sched_switch()
even if it was delayed and is still on the runqueue.

  [ prateek: Broke off the relevant part from [1], commit message ]

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: Peter Zijlstra (Intel) <[email protected]>
Not-yet-signed-off-by: Peter Zijlstra <[email protected]>
Signed-off-by: K Prateek Nayak <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Tested-by: Johannes Weiner <[email protected]>
Link: https://lore.kernel.org/lkml/[email protected]/ [1]

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