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Created attachment 1214204[details]
GDB debug info
Description of problem:
Boot up a guest with one virtio rng device; after the guest boots up, stop the rngd service, and hot unplug the virtio rng device; then try to hot plug/unplug 4 virtio rng devices successively; after 2-5 mins following the hot unplug, the guest crashed for 'Segmentation fault (core dumped)'
Version-Release number of selected component (if applicable):
Host kernel: 3.10.0-514.el7.x86_64
Guest kernel: 3.10.0-514.el7.x86_64
Qemu-kvm: qemu-kvm-1.5.3-126.el7.x86_64
How reproducible:
100%
Steps to Reproduce:
1. Boot up a guest with a virtio rng device:
/usr/libexec/qemu-kvm \
-name 'avocado-vt-vm1' \
-sandbox off \
-machine pc \
-vga cirrus \
-chardev socket,id=qmp_id_qmp1,path=/var/tmp/avocado_1,server,nowait \
-mon chardev=qmp_id_qmp1,mode=control \
-device usb-ehci,id=usb1,bus=pci.0 \
-device virtio-scsi-pci,id=virtio_scsi_pci0,bus=pci.0 \
-drive id=drive_image1,if=none,snapshot=off,aio=native,cache=none,format=qcow2,file=/usr/share/avocado/data/avocado-vt/images/RHEL-Server-7.3-64-virtio-scsi.qcow2 \
-device scsi-hd,id=image1,drive=drive_image1 \
-device virtio-net-pci,mac=9a:57:58:59:5a:5b,id=idXXQhp1,vectors=4,netdev=idfZuynp,bus=pci.0 \
-netdev tap,id=idfZuynp,vhost=on \
-object rng-random,filename=/dev/random,id=rng_0 \
-device virtio-rng-pci,id=rng0,rng=rng_0,bus=pci.0 \
-m 1024 \
-smp 2,maxcpus=2,cores=2,threads=1,sockets=1 \
-device usb-tablet,id=usb-tablet1,bus=usb1.0,port=1 \
-vnc :0 \
-rtc base=utc,clock=host,driftfix=slew \
-boot order=cdn,once=c,menu=off,strict=off \
-enable-kvm \
-monitor stdio
2. After the guest boots up, stop rngd service inside the guest:
# service rngd stop
3. Hot unplug the rng device in qmp:
nc -U /var/tmp/avocado_1
{"QMP": {"version": {"qemu": {"micro": 3, "minor": 5, "major": 1}, "package": " (qemu-kvm-1.5.3-126.el7)"}, "capabilities": []}}
{"execute":"qmp_capabilities"}
{"return": {}}
{"execute":"device_del","arguments":{"id":"rng0"}}
{"return": {}}
4. Then hot plug 4 virtio rng devices
{"execute":"device_add","arguments":{"driver":"virtio-rng-pci","id":"rng0"}}
{"return": {}}
{"execute":"device_add","arguments":{"driver":"virtio-rng-pci","id":"rng1"}}
{"return": {}}
{"execute":"device_add","arguments":{"driver":"virtio-rng-pci","id":"rng2"}}
{"return": {}}
{"execute":"device_add","arguments":{"driver":"virtio-rng-pci","id":"rng3"}}
{"return": {}}
5. Hot unplug the 4 plugged rng devices
{"execute":"device_del","arguments":{"id":"rng0"}}
{"return": {}}
{"execute":"device_del","arguments":{"id":"rng1"}}
{"return": {}}
{"execute":"device_del","arguments":{"id":"rng2"}}
{"return": {}}
{"execute":"device_del","arguments":{"id":"rng3"}}
{"return": {}}
Actual results:
After step5, the guest crashed in hmp:
(qemu) Segmentation fault (core dumped)
Expected results:
Guest works well after the hot unplug of rng devices in step5.
Additional info:
1. Failed to reproduce the bug on latest qemu-kvm-rhev host:
Host kernel: 3.10.0-514.el7.x86_64
Guest kernel: 3.10.0-514.el7.x86_64
Qemu-kvm-rhev: qemu-kvm-rhev-2.6.0-27.el7.x86_64
2. The core file core.3306 is saved in nfs server 10.73.194.27:/vol/s2coredump, while its debug info is attached.
Amit,
As said in description of the bug, I had failed to reproduce the bug on following qemu-kvm-rhev host:
Host kernel: 3.10.0-514.el7.x86_64
Guest kernel: 3.10.0-514.el7.x86_64
Qemu-kvm-rhev: qemu-kvm-rhev-2.6.0-27.el7.x86_64
I have tried on latest rhel7.3z qemu-kvm-rhev versions, it's also a failure to produce the bug:
Host kernel: 3.10.0-514.10.1.el7.x86_64
Qemu-kvm-rhev: qemu-kvm-rhev-2.6.0-28.el7_3.3.x86_64
Guest kernel: 3.10.0-514.el7.x86_64
I also tried on latest rhel7.4 qemu-kvm versions, it's a failure to reproduce the too. So it's curious, I will try other test, no all would fail to reproduce it, we can close it.
Host kernel: 3.10.0-514.10.1.el7.x86_64
Qemu-kvm: qemu-kvm-1.5.3-130.el7.x86_64
Guest kernel: 3.10.0-514.el7.x86_64
Created attachment 1248367[details]
gdb_info-02072017
Reproduced the bug on RHEL7.4, however, the reproduce rate is 2/4 intead of the original 100%:
Host kernel: 3.10.0-556.el7.x86_64
Guest kernel: 3.10.0-514.el7.x86_64
Qemu kvm: qemu-kvm-1.5.3-130.el7.x86_64
You can get the core file core.15846 in nfs server 10.73.194.27:/vol/s2coredump.
(In reply to Gu Nini from comment #4)
> Created attachment 1248367[details]
> gdb_info-02072017
>
> Reproduced the bug on RHEL7.4, however, the reproduce rate is 2/4 intead of
> the original 100%:
>
Please note I have reproduced the bug on an **amd** host with latest qemu-kvm 7.4 version, while failed to reproduce it on intel host with the same version in comment #3, and also failed to reproduce it on both intel and amd hosts with latest qemu-kvm-rhev 7.3z version.
Created attachment 1214204 [details] GDB debug info Description of problem: Boot up a guest with one virtio rng device; after the guest boots up, stop the rngd service, and hot unplug the virtio rng device; then try to hot plug/unplug 4 virtio rng devices successively; after 2-5 mins following the hot unplug, the guest crashed for 'Segmentation fault (core dumped)' Version-Release number of selected component (if applicable): Host kernel: 3.10.0-514.el7.x86_64 Guest kernel: 3.10.0-514.el7.x86_64 Qemu-kvm: qemu-kvm-1.5.3-126.el7.x86_64 How reproducible: 100% Steps to Reproduce: 1. Boot up a guest with a virtio rng device: /usr/libexec/qemu-kvm \ -name 'avocado-vt-vm1' \ -sandbox off \ -machine pc \ -vga cirrus \ -chardev socket,id=qmp_id_qmp1,path=/var/tmp/avocado_1,server,nowait \ -mon chardev=qmp_id_qmp1,mode=control \ -device usb-ehci,id=usb1,bus=pci.0 \ -device virtio-scsi-pci,id=virtio_scsi_pci0,bus=pci.0 \ -drive id=drive_image1,if=none,snapshot=off,aio=native,cache=none,format=qcow2,file=/usr/share/avocado/data/avocado-vt/images/RHEL-Server-7.3-64-virtio-scsi.qcow2 \ -device scsi-hd,id=image1,drive=drive_image1 \ -device virtio-net-pci,mac=9a:57:58:59:5a:5b,id=idXXQhp1,vectors=4,netdev=idfZuynp,bus=pci.0 \ -netdev tap,id=idfZuynp,vhost=on \ -object rng-random,filename=/dev/random,id=rng_0 \ -device virtio-rng-pci,id=rng0,rng=rng_0,bus=pci.0 \ -m 1024 \ -smp 2,maxcpus=2,cores=2,threads=1,sockets=1 \ -device usb-tablet,id=usb-tablet1,bus=usb1.0,port=1 \ -vnc :0 \ -rtc base=utc,clock=host,driftfix=slew \ -boot order=cdn,once=c,menu=off,strict=off \ -enable-kvm \ -monitor stdio 2. After the guest boots up, stop rngd service inside the guest: # service rngd stop 3. Hot unplug the rng device in qmp: nc -U /var/tmp/avocado_1 {"QMP": {"version": {"qemu": {"micro": 3, "minor": 5, "major": 1}, "package": " (qemu-kvm-1.5.3-126.el7)"}, "capabilities": []}} {"execute":"qmp_capabilities"} {"return": {}} {"execute":"device_del","arguments":{"id":"rng0"}} {"return": {}} 4. Then hot plug 4 virtio rng devices {"execute":"device_add","arguments":{"driver":"virtio-rng-pci","id":"rng0"}} {"return": {}} {"execute":"device_add","arguments":{"driver":"virtio-rng-pci","id":"rng1"}} {"return": {}} {"execute":"device_add","arguments":{"driver":"virtio-rng-pci","id":"rng2"}} {"return": {}} {"execute":"device_add","arguments":{"driver":"virtio-rng-pci","id":"rng3"}} {"return": {}} 5. Hot unplug the 4 plugged rng devices {"execute":"device_del","arguments":{"id":"rng0"}} {"return": {}} {"execute":"device_del","arguments":{"id":"rng1"}} {"return": {}} {"execute":"device_del","arguments":{"id":"rng2"}} {"return": {}} {"execute":"device_del","arguments":{"id":"rng3"}} {"return": {}} Actual results: After step5, the guest crashed in hmp: (qemu) Segmentation fault (core dumped) Expected results: Guest works well after the hot unplug of rng devices in step5. Additional info: 1. Failed to reproduce the bug on latest qemu-kvm-rhev host: Host kernel: 3.10.0-514.el7.x86_64 Guest kernel: 3.10.0-514.el7.x86_64 Qemu-kvm-rhev: qemu-kvm-rhev-2.6.0-27.el7.x86_64 2. The core file core.3306 is saved in nfs server 10.73.194.27:/vol/s2coredump, while its debug info is attached.