Re: [PATCH] hostmem: don't use mbind() if host-nodes is epmty

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 11 May 2020 18:00:01 +0200
Philippe Mathieu-Daudé <philmd@redhat.com> wrote:

> Hi Eduardo,
> 
> On 5/4/20 5:44 PM, Eduardo Habkost wrote:
> > On Thu, Apr 30, 2020 at 11:46:06AM -0400, Igor Mammedov wrote:  
> >> Since 5.0 QEMU uses hostmem backend for allocating main guest RAM.
> >> The backend however calls mbind() which is typically NOP
> >> in case of default policy/absent host-nodes bitmap.
> >> However when runing in container with black-listed mbind()
> >> syscall, QEMU fails to start with error
> >>   "cannot bind memory to host NUMA nodes: Operation not permitted"
> >> even when user hasn't provided host-nodes to pin to explictly
> >> (which is the case with -m option)
> >>
> >> To fix issue, call mbind() only in case when user has provided
> >> host-nodes explicitly (i.e. host_nodes bitmap is not empty).
> >> That should allow to run QEMU in containers with black-listed
> >> mbind() without memory pinning. If QEMU provided memory-pinning
> >> is required user still has to white-list mbind() in container
> >> configuration.
> >>
> >> Reported-by: Manuel Hohmann <mhohmann@physnet.uni-hamburg.de>
> >> Signed-off-by: Igor Mammedov <imammedo@redhat.com>  
> > 
> > Queued on machine-next, thanks!  
> 
> I've been debugging this issue again today and figured it was not 
> merged, if possible can you add the "Cc: qemu-stable@nongnu.org" tag 
> before sending your pull request?
it's CCed already, so my impression was that will should picked up once it was reviewed.

> 
> Thanks,
> 
> Phil.
>