From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: [PATCH net-next 3/3] vhost: access vq metadata through kernel
 virtual address
Date: Thu, 13 Dec 2018 16:18:40 -0500
Message-ID: <20181213211840.GC18692@char.us.oracle.com>
References: <20181213101022.12475-1-jasowang@redhat.com>
 <20181213101022.12475-4-jasowang@redhat.com>
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Cc: Jason Wang <jasowang@redhat.com>, kvm@vger.kernel.org,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
To: "Michael S. Tsirkin" <mst@redhat.com>
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.giant snip..
> > +	npinned = get_user_pages_fast(uaddr, npages, write, pages);
> > +	if (npinned != npages)
> > +		goto err;
> > +
> 
> As I said I have doubts about the whole approach, but this
> implementation in particular isn't a good idea
> as it keeps the page around forever.
> So no THP, no NUMA rebalancing, userspace-controlled
> amount of memory locked up and not accounted for.
> 
> Don't get me wrong it's a great patch in an ideal world.
> But then in an ideal world no barriers smap etc are necessary at all.

So .. suggestions on how this could be accepted? As in other ways
where we still get vmap and the issues you mentioned are not troubling you?

Thanks!