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This bug has been copied from bug #1270144 and has been proposed to be backported to 7.2 z-stream (EUS).
Reproduce: kernel: 3.10.0-329.el7.x86_64 qemu-kvm: qemu-kvm-rhev-2.3.0-31.el7.x86_64 steps: 1. prepare hugepages env: #cat /proc/cmdline BOOT_IMAGE=/vmlinuz-3.10.0-329.el7.x86_64 root=/dev/mapper/rhel_dhcp--10--61-root ro console=tty0 console=ttyS0,115200 reboot=pci crashkernel=auto rd.lvm.lv=rhel_dhcp-10-61/root rd.lvm.lv=rhel_dhcp-10-61/swap biosdevname=0 rhgb intel_iommu=on default_hugepagesz=1G hugepagesz=1G hugepages=4 hugepagesz=2M hugepages=0 #mount ... hugetlbfs on /dev/hugepages1G type hugetlbfs (rw,relatime,pagesize=1G) ... # cat /proc/meminfo | grep Huge AnonHugePages: 24576 kB HugePages_Total: 8 HugePages_Free: 8 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 1048576 kB 2. start a guest with 1G hugepage: /usr/libexec/qemu-kvm -name rhel72-sn5 -m 4G,slots=8,maxmem=40G -mem-prealloc -mem-path /dev/hugepages1G -numa node \ -realtime mlock=on \ -smp 16,sockets=16,cores=1,threads=1 \ -no-user-config -nodefaults -rtc base=utc,driftfix=slew -global kvm-pit.lost_tick_policy=discard -boot menu=on,strict=on \ -object iothread,id=iothread0 -drive file=/home/guest/rhel72-sn5.img,if=none,id=drive-data-disk,format=qcow2,cache=none,aio=native,werror=stop,rerror=stop -device virtio-blk-pci,drive=drive-data-disk,id=data-disk,iothread=iothread0,bus=pci.0,addr=0x7 \ -netdev tap,id=hostnet1,vhost=on -device e1000,netdev=hostnet1,id=net2,mac=10:1a:4a:42:0a:0b,bus=pci.0,addr=0xa \ -usb -device usb-tablet,id=input0 -vga qxl \ -spice port=5901,addr=0.0.0.0,disable-ticketing,image-compression=off,seamless-migration=on -monitor stdio \ -msg timestamp=on 3. hotplug a memory device with size=512M (qemu) object_add memory-backend-file,id=mem0,size=512M,mem-path=/dev/hugepages1G 2015-11-13T07:41:46.486441Z memory size 0x20000000 must be equal to or larger than huge page size 0x40000000 And the qemu process exit. So, the bug is reproduced. Verify: kernel: 3.10.0-331.el7.x86_64 qemu-kvm: qemu-kvm-rhev-2.3.0-31.el7_2.2 With same steps as above. The guest doesn't quit, and HMP prints "memory size 0x20000000 must be equal to or larger than huge page size 0x40000000". So, the bug is fixed.
Reverify: kernel: 3.10.0-327.3.1.el7.x86_64 qemu-kvm: qemu-kvm-rhev-2.3.0-31.el7_2.3 QE retest on above environment as same steps as comment 3, The guest doesn't quit, and HMP prints "memory size 0x20000000 must be equal to or larger than huge page size 0x40000000". So the bug is fixed.
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/RHBA-2015-2555.html