Re: [PATCH] kvm balloon guest driver (v2)

[Dor Laor <dor.laor-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Thu, 2008-01-10 at 21:27 +0900, Akio Takebe wrote:
> Hi, Marcelo
> 
> >> >+static int kvm_balloon_inflate(struct virtballoon *v, int32_t npages)
> >> >+{
> >> >+	LIST_HEAD(tmp_list);
> >> >+	struct page *page, *tmp;
> >> >+	struct balloon_buf *buf;
> >> >+	u32 *pfn;
> >> >+	int allocated = 0;
> >> >+	int i, r = -ENOMEM;
> >> >+
> >> >+	buf = alloc_balloon_buf(v->vdev, GFP_KERNEL);
> >> When does balloon driver free the buf?
> >
> >Hi Akio,
> >
> >The buffers are passed from the virtio handling routine to the balloon_thread
> >through the balloon_work list, and then freed here:
> >
> >+               spin_lock_irq(&v->queue_lock);
> >+               while (!list_empty(&v->balloon_work)) {
> >+                       struct balloon_work *work;
> >+                       struct balloon_buf *buf;
> >+
> >+                       work = list_entry(v->balloon_work.next,
> >+                                        struct balloon_work, list);
> >+                       list_del(&work->list);
> >+                       spin_unlock_irq(&v->queue_lock);
> >+                       buf = work->buf;
> >+                       kfree(work);
> >+
> >+                       switch(buf->hdr.cmd) {
> >+                       case CMD_BALLOON_DEFLATE:
> >+                               deflate_done(v, buf);
> >+                               break;
> >+                       case CMD_BALLOON_INFLATE:
> >+                               inflate_done(v, buf);
> >+                               break;
> >+                       default:
> >+                               printk("%s: unknown cmd 0x%x\n", __func__,
> >+                                       buf->hdr.cmd);
> >+                       }
> >+                       kfree(buf);
> Thank you for your exlanation.
> Does balloon free the buf when kvm_balloon_xflate() retrun -ENOMEM?

It return -ENOMEM only when kvm_balloon_inflate fails.
We just need to handle this case a little better - there is no leak but
the xflate function or the balloon thread need to check the value
and update the host that it failed to reach the requested balloon size.


> Akio Takebe
> 
> 
> -------------------------------------------------------------------------
> Check out the new SourceForge.net Marketplace.
> It's the best place to buy or sell services for
> just about anything Open Source.
> http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace
> _______________________________________________
> kvm-devel mailing list
> kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
> https://lists.sourceforge.net/lists/listinfo/kvm-devel


-------------------------------------------------------------------------
Check out the new SourceForge.net Marketplace.
It's the best place to buy or sell services for
just about anything Open Source.
http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace