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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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