Re: [libvirt] [PATCH] qemu: fix migration fail of an auto-placementvm after attached memory to it

>On Sat, Jul 22, 2017 at 05:45:59 -0400, Yi Wang wrote: >> This patch fix this condition: >> -vm has the "auto" placement in vcpu >> -hot-plug memory with source node "1-3" through attach-device command >> -migrate the vm to a host with only 2 numa node >> And the migration will fail with error: >> "error: unsupported configuration: NUMA node 2 is unavailable" >> >> Signed-off-by: Yi Wang <wang yi59 zte com cn> >> Signed-off-by: Xi Xu <xu xi8 zte com cn> >> --- >> src/qemu/qemu_process.c | 10 ++++++++++ >> 1 file changed, 10 insertions(+) >> >> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c >> index 7b708be..dcc564c 100644 >> --- a/src/qemu/qemu_process.c >> +++ b/src/qemu/qemu_process.c >> @@ -5259,6 +5259,16 @@ qemuProcessPrepareDomain(virConnectPtr conn, >> goto cleanup >> } >> >> + VIR_DEBUG("Updating memory source nodes") >> + for (i = 0 i < vm->def->nmems i++) { >> + virDomainMemoryDefPtr mem = vm->def->mems[i] >> + if (priv->autoNodeset && mem && mem->sourceNodes) { >> + virBitmapFree(mem->sourceNodes) >> + if (!(mem->sourceNodes = virBitmapNewCopy(priv->autoNodeset))) >> + goto cleanup > >This is not correct. This code will be executed even during normal >startup and it would remove any manual pinning the user set-up. What you said is right, this is indeed a problem that my patch ignored. > >I think the problem might be that the XML retains the nodesets of >automatically placed memory modules while formatting the migratable XML. The problem is that the source nodemask specified in the "virsh attach-device" XML, which doesn't exist in the destination host. For example: <memory model='dimm'> <target> <size unit='MiB'>1024</size> <node>0</node> </target> <source> <nodemask>1-3</nodemask> </source> </memory> The source of the problem is that we must set source nodemask when hot-plug memory dimm when the VM has auto placement, or it failed: # virsh attach-device centos mem_hp.xml error: Failed to attach device from mem_hp.xml error: internal error: Advice from numad is needed in case of automatic numa placement

And after we set source nodemask, it might fail to migrate. So, a better way to work around this problem is add a "auto" supported to <source>?

Any other suggestion?