Jan Kiszka wrote:
> Gilles Chanteperdrix wrote:
>> Jan Kiszka wrote:
>>> Jan Kiszka wrote:
>>>> It's still unclear what goes on precisely, we are still digging, but the
>>>> test system that can produce this is highly contended.
>>> Short update: Further instrumentation revealed that cr3 differs from
>>> active_mm->pgd while we are looping over that fault, ie. the kernel
>>> tries to fixup the wrong mm. And that means we have some open race
>>> window between updating cr3 and active_mm somewhere (isn't switch_mm run
>>> in a preemptible manner now?).
>> Maybe the rsp is wrong and leads you to the wrong active_mm ?
>>
>>> As a first shot I disabled CONFIG_IPIPE_DELAYED_ATOMICSW, and we are now
>>> checking if it makes a difference. Digging deeper into the code in the
>>> meanwhile...
>> As you have found out in the mean time, we do not use unlocked context
>> switches on x86.
>>
> 
> Yes.
> 
> The last question I asked myself (but couldn't answer yet due to other
> activity) was: Where are the local_irq_disable/enable_hw around
> switch_mm for its Linux callers?

prepare_arch_switch and task_hijacked

-- 
                                          Gilles


_______________________________________________
Xenomai-core mailing list
Xenomai-core@gna.org
https://mail.gna.org/listinfo/xenomai-core

Reply via email to