Re: [PULL] vhost: cleanups and fixes

From: Linus Torvalds
Date: Mon Jun 11 2018 - 14:33:02 EST

On Mon, Jun 11, 2018 at 9:24 AM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:

Is this really a good idea?

Plus it seems entirely broken.

The report_pfn_range() callback is done under the zone lock, but
virtio_balloon_send_free_pages() (which is the only callback used that
I can find) does add_one_sg(), which does virtqueue_add_inbuf(vq, &sg,
1, vq, GFP_KERNEL);

So now we apparently do a GFP_KERNEL allocation insider the mm zone
lock, which is broken on just _so_ many levels.

Pulled and then unpulled again.

Either somebody needs to explain why I'm wrong and you can re-submit
this, or this kind of garbage needs to go away.

I do *not* want to be in the situation where I pull stuff from the
virtio people that adds completely broken core VM functionality.

Because if I'm in that situation, I will stop pulling from you guys.
Seriously. You have *no* place sending me broken shit that is outside
the virtio layer.

Subsystems that break code MM will get shunned. You just aren't
important enough to allow you breaking code VM.