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SubjectRe: [PATCH 2/3] work_on_cpu: Use our own workqueue.
Ingo Molnar wrote:
> * Oleg Nesterov <oleg@redhat.com> wrote:
>
>> But "[PATCH 1/3] work_on_cpu: dont try to get_online_cpus() in
>> work_on_cpu." removes get_online_cpus/put_online_cpus, this means the
>> work can run on the wrong CPU anyway. Or work_on_cpu() can hang forever
>> if CPU has already gone away before queue_work_on().
>>
>> Confused.
>
> The idea was to require work_on_cpu() users to be CPU hotplug-safe. But
> ... Rusty pointed it out in the past that this might be fragile, and we
> could put back the get_online_cpus()/put_online_cpus() calls.
>
> Rusty, what do you think?
>
> Ingo


I believe that is the intention, in that the caller should insure that
the cpu does not go offline. But also as Rusty stated, the previous usages
of set_cpus_allowed did not always insure this, so it's at least not a
regression.

I'll put it on my todo list to check the references in tip/cpus4096 to see
where they stand on the get_online_cpus() issue.

Thanks,
Mike


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