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Re: [Xen-devel] [PATCH v6 00/20] xen: add core scheduling support



On 03.10.19 11:47, Sergey Dyasli wrote:
Hi Juergen,

Looks like we've hit the first Xen crash with core scheduling patches applied.
The log is below. From my analysis it seems that CSCHED_PCPU is NULL.
I suspect this is connected to commit b0000b128adb
("sched: populate cpupool0 only after all cpus are up")

Could you take a look, please?

The main reason is that sched_tick_resume() should call
sched_do_tick_resume() only with the scheduling lock held.

This has been a latent bug since ages, but my patches (especially
"sched: add minimalistic idle scheduler for free cpus" in combination
with "sched: populate cpupool0 only after all cpus are up") is
triggering it much easier now.

In the past you'd need to remove a cpu from a cpupool with null, rt or
arinc653 scheduler with default scheduler being credit in order to have
a chance hitting the bug.

I'll send a patch.


Juergen

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