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    SubjectRe: INFO: rcu detected stall in do_idle
    On Tue, Oct 16, 2018 at 03:24:06PM +0200, Thomas Gleixner wrote:
    > It does reproduce here but with a kworker stall. Looking at the reproducer:
    >
    > *(uint32_t*)0x20000000 = 0;
    > *(uint32_t*)0x20000004 = 6;
    > *(uint64_t*)0x20000008 = 0;
    > *(uint32_t*)0x20000010 = 0;
    > *(uint32_t*)0x20000014 = 0;
    > *(uint64_t*)0x20000018 = 0x9917;
    > *(uint64_t*)0x20000020 = 0xffff;
    > *(uint64_t*)0x20000028 = 0;
    > syscall(__NR_sched_setattr, 0, 0x20000000, 0);
    >
    > which means:
    >
    > struct sched_attr {
    > .size = 0,
    > .policy = 6,
    > .flags = 0,
    > .nice = 0,
    > .priority = 0,
    > .deadline = 0x9917,
    > .runtime = 0xffff,
    > .period = 0,
    > }
    >
    > policy 6 is SCHED_DEADLINE
    >
    > That makes the thread hog the CPU and prevents all kind of stuff to run.
    >
    > Peter, is that expected behaviour?

    Sorta, just like FIFO-99 while(1);. Except we should be rejecting the
    above configuration, because of the rule:

    runtime <= deadline <= period

    Juri, where were we supposed to check that?

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