linux-kernel - Re: [PATCH v34 0/4] Virtio-balloon: support free page reporting

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Message-ID: <909d0983-bb54-25bb-03f5-7a28ded76500@redhat.com>
Date:   Fri, 29 Jun 2018 17:28:56 +0200
From:   David Hildenbrand <david@...hat.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     Wei Wang <wei.w.wang@...el.com>, virtio-dev@...ts.oasis-open.org,
        linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org,
        linux-mm@...ck.org, mhocko@...nel.org, akpm@...ux-foundation.org,
        torvalds@...ux-foundation.org, pbonzini@...hat.com,
        liliang.opensource@...il.com, yang.zhang.wz@...il.com,
        quan.xu0@...il.com, nilal@...hat.com, riel@...hat.com,
        peterx@...hat.com
Subject: Re: [PATCH v34 0/4] Virtio-balloon: support free page reporting

>> And looking at all the discussions and problems that already happened
>> during the development of this series, I think we should rather look
>> into how clean free page hinting might solve the same problem.
> 
> I'm not sure I follow the logic. We found that neat tricks
> especially re-using the max order free page for reporting.

Let me rephrase: history of this series showed that this is some really
complicated stuff. I am asking if this complexity is actually necessary.

No question that we had a very valuable outcome so far (that especially
is also relevant for other projects like Nitesh's proposal - talking
about virtio requests and locking).

> 
>> If it can't be solved using free page hinting, fair enough.
> 
> I suspect Nitesh will need to find a way not to have mm code
> call out to random drivers or subsystems before that code
> is acceptable.
> 
> 


-- 

Thanks,

David / dhildenb