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    SubjectRe: "Dying CPU not properly vacated" splat
    On Tue, Aug 02, 2022 at 10:30:02AM +0100, Valentin Schneider wrote:
    > On 05/07/22 10:23, Paul E. McKenney wrote:
    > > The second of these occurred near shutdown, but the first was quite some
    > > time before shutdown. In case that makes a difference.
    > >
    > > I have not seen this since.
    > >
    > > Any other diagnostics I should add?
    > >
    >
    > Sorry, I let this get buried to the bottom of my inbox :(
    >
    > I've had another look at rcutorture.c but just like for
    > rcu_torture_reader(), I don't see any obvious culprit (no
    > kthread_set_per_cpu() usage)).
    >
    > One thing I think would help is a scheduling trace (say sched_switch,
    > sched_wakeup and cpuhp*, combined with ftrace_dump_on_oops + panic_on_warn
    > ?) - that should at least tell us if the issue is in the wakeup placement
    > (if the task gets placed on a dying CPU *after* CPUHP_AP_ACTIVE), or in the
    > balance_push() mechanism (the task was *already* on the CPU when it started
    > dying and never moved away).
    >
    > Neither make sense to me, but it has to be somewhere in there...

    And given that it has been more than a year since I have seen this,
    I am considering it to be fixed, whether purposefully or accidentally.

    Thanx, Paul

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