Red Hat Bugzilla – Bug 617085
core dumped when add netdev to VM with vhost on
Last modified: 2015-03-04 19:51:56 EST
Description of problem: core dumped when add netdev with vhost on for window guest Version-Release number of selected component (if applicable): virtio-win-1.1.8-0 kernel-2.6.32-44.1.el6.x86_64 qemu-kvm-0.12.1.2-2.96.el6.x86_64 How reproducible: always Steps to Reproduce: 1.Run windows guest with cli: /usr/libexec/qemu-kvm -m 2G -smp 2 -cpu qemu64,+x2apic -usbdevice tablet -drive file=/home/win08R2.raw,if=none,id=drive-virtio0,boot=on,werror=stop,rerror=stop,cache=none,format=raw -device virtio-blk-pci,drive=drive-virtio0,id=virtio-blk-pci0 -netdev tap,id=hostnet0,script=/etc/qemu-ifup,vhost=on,ifname=virtio_nic_1 -device virtio-net-pci,netdev=hostnet0,mac=02:00:78:3F:20:1f,bus=pci.0 -netdev tap,id=hostnet1,script=/etc/qemu-ifup,ifname=e1000_1_1 -device e1000,netdev=hostnet1,mac=01:00:78:3F:20:1f,bus=pci.0,id=e1000-1 -uuid 1234127c-8765-4e67-95da-8dd0a8891cc4 -name winxp -qmp tcp:0:4445,server,nowait -boot c -monitor stdio -spice port=5930,disable-ticketing -vga qxl 2.Install virtio network driver from http://download.lab.bos.redhat.com/devel/RHEV/virtio-win/1.1.8-0/ 3.do netdev hot add from qmp : { "execute": "netdev_add", "arguments":{"type":"tap","id":"hostnet2","script":"/etc/qemu-ifup","vhost":"on","ifname":"virtio_nic_plug"}} or from monitor: netdev_add tap,id=hostnet3,script=/etc/qemu-ifup,vhost=on,ifname=virtio_nic_3 Actual results: Core dumped and qemu aborted after step3,please see attached core dump analyze file. Expected results: netdev should be added. Additional info: This issue does not exist when not using vhost. { "execute": "netdev_add", "arguments":{"type":"tap","id":"hostnet2","script":"/etc/qemu-ifup","ifname":"virtio_nic_plug"}}
Created attachment 433613 [details] coredump-analyze
This issue has been proposed when we are only considering blocker issues in the current Red Hat Enterprise Linux release. ** If you would still like this issue considered for the current release, ask your support representative to file as a blocker on your behalf. Otherwise ask that it be considered for the next Red Hat Enterprise Linux release. **
I can reproduce this bug when adding netdev to linux guests. qemu) netdev_add tap,id=hostnet1,script=/etc/qemu-ifup-switch,vhost=on,ifname=virtio_nic_1 qemu-kvm: /builddir/build/BUILD/qemu-kvm-0.12.1.2/hw/vhost.c:122: vhost_dev_unassign_memory: Assertion `to >= 0' failed Change subject to 'core dumped when add netdev to VM with vhost on'
What happens when vhost-off?
Not sure if this is related, but in the backtrace it has vhost_client_set_memory() calling vhost_dev_unassign_memory(). However the code does this: vhost_dev_unassign_memory(dev, start_addr, size); if (flags == IO_MEM_RAM) { /* Add given mapping, merging adjacent regions if any */ vhost_dev_assign_memory(dev, start_addr, size, (uintptr_t)qemu_get_ram_ptr(phys_offset)); } else { /* Remove old mapping for this memory, if any. */ vhost_dev_unassign_memory(dev, start_addr, size); } Ie. if flags != IO_MEM_RAM, we end up calling vhost_dev_unassign_memory() twice with the exact same arguments..... Could it be the first call to vhost_dev_unassign_memory() shouldn't be there? Jes
(In reply to comment #5) > What happens when vhost-off? When use vhost=off or without vhost parameter, netdev can be added successfully.
I can reproduce this, but I don't see it with upstream qemu or qemu-kvm.
Ok, spoke too fast, it happens with upstream qemu-kvm too, there is just a delay from entering the command until it crashes.
Verify this bug on RHEL6 and win7 guest with qemu-kvm-0.12.1.2-2.104.el6, this bug does not exist when add netdev with vhost on. Change status to verified.
Red Hat Enterprise Linux 6.0 is now available and should resolve the problem described in this bug report. This report is therefore being closed with a resolution of CURRENTRELEASE. You may reopen this bug report if the solution does not work for you.