[libvirt] [PATCH 4/4] qemuSetupCpusetCgroup: Set up cpuset.mems before execing qemu

It's funny how this went unnoticed for such a long time. Long story short, if a domain is configured with VIR_DOMAIN_NUMATUNE_MEM_STRICT libvirt doesn't really honour that. This is because of 7e72ac787848 after which libvirt allowed qemu to allocate memory just anywhere and only after that it used some magic involving cpuset.memory_migrate and cpuset.mems to move the memory to desired NUMA nodes. This was done in order to work around some KVM bug where KVM would fail if there wasn't a DMA zone available on the NUMA node. Well, while the work around might stopped libvirt tickling the KVM bug it also caused a bug on libvirt side: if there is not enough memory on configured NUMA node(s) then any attempt to start a domain must fail. Because of the way we play with guest memory domains can start just happily. Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/qemu/qemu_cgroup.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/src/qemu/qemu_cgroup.c b/src/qemu/qemu_cgroup.c index b2d300b419..d6c982aeed 100644 --- a/src/qemu/qemu_cgroup.c +++ b/src/qemu/qemu_cgroup.c @@ -869,6 +869,9 @@ qemuSetupCpusetCgroup(virDomainObjPtr vm) if (virCgroupSetCpusetMemoryMigrate(priv->cgroup, true) < 0) return -1; + if (qemuSetupCpusetMems(vm) < 0) + return -1; + return 0; } -- 2.21.0