Re: Memory hotplug softlock issue

[David Hildenbrand]

>>> Failing on ENOMEM is a questionable thing. I haven't seen that happening
>>> wildly but if it is a case then I wouldn't be opposed.
>>>
>>>> You mentioned memory pressure, if our host is under memory pressure we
>>>> can easily trigger running into an endless loop there, because we
>>>> basically ignore -ENOMEM e.g. when we cannot get a page to migrate some
>>>> memory to be offlined. I assume this is the case here.
>>>> do_migrate_range() could be the bad boy if it keeps failing forever and
>>>> we keep retrying.
>>
>> I've seen quite some issues while playing with virtio-mem, but didn't
>> have the time to look into the details. Still on my long list of things
>> to look into.
> 
> Memory hotplug is really far away from being optimal and robust. This
> has always been the case. Issues used to be workaround by retry limits
> etc. If we ever want to make it more robust we have to bite a bullet and
> actually chase all the issues that might be basically anywhere and fix
> them. This is just a nature of a pony that memory hotplug is.
> 

Yes I agree, no more workarounds.

-- 

Thanks,

David / dhildenb