On Thu, May 08, 2014 at 04:51:56PM +0200, Paolo Bonzini wrote:
> Il 06/05/2014 11:27, Hu Tao ha scritto:
> > This series includes work on QOMifying the memory backends.
> > the idea is to delegate all properties of the memory backend to
> > a new QOM class hierarchy, in which the concrete classes
> > are hostmem-ram and hostmem-file. The backend is passed to the
> > machine via "-numa node,memdev=foo" where "foo" is the id of the
> > backend object.
>
> Hello,
>
> I noticed now that if you have the host-nodes property set Linux
> requires you to set a policy other than "default" too. If you don't,
> the mbind system call fails.
>
> What about squashing something like this?
>
> Paolo
>
> diff --git a/backends/hostmem.c b/backends/hostmem.c
> index d3f8476..a0a3111 100644
> --- a/backends/hostmem.c
> +++ b/backends/hostmem.c
> @@ -299,12 +299,23 @@ host_memory_backend_memory_init(UserCreatable *uc,
> Error **errp)
>
> #ifdef CONFIG_NUMA
> unsigned long maxnode = find_last_bit(backend->host_nodes, MAX_NODES);
> + unsigned policy = backend->policy;
> +
> + /* Linux does not accept MPOL_DEFAULT with nonzero bitmap, but
> + * "-object memory-ram,size=128M,hostnodes=0,policy=bind" is a
> + * bit of a mouthful. So if the host_nodes bitmap is nonzero,
> + * pick the BIND policy.
> + */
> + if (find_first_bit(backend->host_nodes, MAX_NODES) != MAX_NODES &&
> + policy == MPOL_DEFAULT) {
> + policy = MPOL_BIND;
> + }
Looks reasonable to me. Thanks!
>
> /* This is a workaround for a long standing bug in Linux'
> * mbind implementation, which cuts off the last specified
> * node.
> */
> - if (mbind(ptr, sz, backend->policy, backend->host_nodes, maxnode + 2,
> 0)) {
> + if (mbind(ptr, sz, policy, backend->host_nodes, maxnode + 2, 0)) {
> error_setg_errno(errp, errno,
> "cannot bind memory to host NUMA nodes");
