On Friday, January 25, 2013 03:03:13 AM Cong Wang wrote:
> ["Followup-To:" header set to gmane.linux.network.]
>
> On Wed, 23 Jan 2013 at 20:46 GMT, Romain Francoise <romain@xxxxxxxxxxxxx>
wrote:
> > Creating a vhost-net device allocates an object large enough (34320 bytes
> > on x86-64) to trigger an order-4 allocation, which may fail if memory if
> >
> > fragmented:
> > libvirtd: page allocation failure: order:4, mode:0x2000d0
> > ...
> > SLAB: Unable to allocate memory on node 0 (gfp=0xd0)
> >
> > cache: size-65536, object size: 65536, order: 4
> > node 0: slabs: 8/8, objs: 8/8, free: 0
> >
> > In that situation, rather than forcing the caller to use regular
> > virtio-net, try to allocate the descriptor with vmalloc().
>
> The real problem is vhost_net struct is really big, it
> should be reduced rather than workarounded like this.
>
Looks like iov in vhost_virtqueue is a little big:
struct iovec iov[UIO_MAXIOV];
Maybe we can use pointer and allocate it like indirect in
vhost_dev_alloc_iovecs().
> > +static void vhost_net_kvfree(void *addr)
> > +{
> > + if (is_vmalloc_addr(addr))
> > + vfree(addr);
> > + else
> > + kfree(addr);
> > +}
> > +
>
> This kind of stuff should really go to mm, not netdev.
>
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