Note: This bug is displayed in read-only format because
the product is no longer active in Red Hat Bugzilla.
RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://rhn.redhat.com/errata/RHSA-2015-0323.html
Description of problem: hot-plug vcpu in NUMA will casue guest exits. From the guest log, it saids: "kvm_init_vcpu failed: Cannot allocate memory" version: libvirt-1.2.8-6.el7.x86_64 qemu-kvm-1.5.3-77.el7.x86_64 kernel-3.10.0-195.el7.x86_64 How reproducible: 100% Step to reproduce: 0. prepare a NUMA, which DMA32 zone is in Node 0. # numactl --hard available: 2 nodes (0-1) node 0 cpus: 0 1 2 3 4 5 6 7 16 17 18 19 20 21 22 23 node 0 size: 65514 MB node 0 free: 63531 MB node 1 cpus: 8 9 10 11 12 13 14 15 24 25 26 27 28 29 30 31 node 1 size: 65536 MB node 1 free: 62750 MB node distances: node 0 1 0: 10 11 1: 11 10 # grep "zone DMA" /proc/zoneinfo Node 0, zone DMA32 1. start a guest with 2 current used vcpu # virsh dumpxml r71 ... <vcpu placement='auto' current='2'>4</vcpu> <numatune> <memory mode='strict' placement='auto'/> </numatune> ... # virsh start r71 numad suggests bind memory to Node 1. # cat /sys/fs/cgroup/cpuset/machine.slice/machine-qemu\\x2dr71.scope/cpuset.mems 1 2. hot-plug vcpu # virsh setvcpus r71 3 error: Unable to read from monitor: Connection reset by peer Expect result: hot-plug works. Work around: before you hot-plug vcpu, change domain's emulator pinning: # echo 0-1 > /sys/fs/cgroup/cpuset/machine.slice/machine-qemu\\x2dr71.scope/cpuset.mems # echo 0-1 > /sys/fs/cgroup/cpuset/machine.slice/machine-qemu\\x2dr71.scope/emulator/cpuset.mems # virsh setvcpus r71 3 # virsh vcpucount r71 maximum config 4 maximum live 4 current config 2 current live 3