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Created attachment 1330947 [details] engine and vdsm log Description of problem: Hotplug memory does not work for VM that configured to use 1 GB hugepages Version-Release number of selected component (if applicable): ovirt-engine-4.2.0-0.0.master.20170921184504.gitfcfc9a7.el7.centos.noarch vdsm-4.20.3-88.git6102334.el7.centos.x86_64 How reproducible: Always Steps to Reproduce: 1. Configure host to have 2 1 GB hugepages # 2 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages 2. Configure VM to have 1 GB memory and custom property hugepages with 1048576 3. Start VM 4. Verify hugepages consumption cat /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages 2 cat /sys/kernel/mm/hugepages/hugepages-1048576kB/free_hugepages 1 5. Hotplug additional 1 GB of memory Actual results: VM still has 1 GB of memory and cat /sys/kernel/mm/hugepages/hugepages-1048576kB/free_hugepages 1 Expected results: VM has 2 GB of memory and cat /sys/kernel/mm/hugepages/hugepages-1048576kB/free_hugepages 0 Additional info: Under the engine log I can see 2017-09-26 12:14:52,322+03 ERROR [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (default task-40) [1ff4d77f] EVENT_ID: FAILED_HOT_SET_MEMORY(2,040), Failed to hot set memory to VM golden_env_mixed_virtio_0. Underlying error message: internal error: unable to execute QEMU command 'object-add': memory size 0x38000000 must be equal to or larger than page size 0x40000000
changing title to explicitely validate it - hotplug indeed does not work for hugepages VMs
I tried hot-plug and also hot-unplug for VM's with 2 MB hugepages and it worked fine. So the question what the expected behavior.
(In reply to Tomas Jelinek from comment #1) > changing title to explicitely validate it - hotplug indeed does not work for > hugepages VMs or rather fix it? it would need special behavior due to the "special" 256MB module...but other than that it should all work
(In reply to Michal Skrivanek from comment #3) > (In reply to Tomas Jelinek from comment #1) > > changing title to explicitely validate it - hotplug indeed does not work for > > hugepages VMs > > or rather fix it? it would need special behavior due to the "special" 256MB > module...but other than that it should all work In theory yes, but it would require quite some testing to make sure it is really working. And considering this is mostly about high perf vms, it is safer to disallow it than to make it work. High perf VMs have anyway lots of limitations we need to handle for 4.3, this can be one of them...
Verified on rhvm-4.2.1.1-0.1.el7.noarch golden_env_mixed_virtio_0: Cannot edit VM. Memory hot set is not supported for virtual machines with huge pages.
This bugzilla is included in oVirt 4.2.1 release, published on Feb 12th 2018. Since the problem described in this bug report should be resolved in oVirt 4.2.1 release, it has been closed with a resolution of CURRENT RELEASE. If the solution does not work for you, please open a new bug report.