Hello LKML,

for some time we experience kernel panics in VMs running 
on Qemu with RBD devices in the sym53c8xx driver (see attachements).

We see at least the following kernels affected:

    3.2.0-4-amd64 (Debian stable)
    3.16.0-4-amd64 (Debian Jessie)
    3.16.0-0.bpo.4-amd64 (Debian backports)

We experience this problem mostly when having high i/o in the VM
and/or load due to rebalancing data.

I was wondering if this can be fixed in the kernel or if it needs to be
addressed differently by changing qemu/ceph parameters.

Our qemu parameters (coming from opennebula) are

    qemu-system-x86_64 -enable-kvm -name one-204 -S -machine pc-i440fx-trusty,accel=kvm,usb=off -m 512 -realtime mlock=off -smp 2,sockets=2,cores=1,threads=1 -uuid d7c3374e-349e-4db6-8f54-f3c607f93101 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/one-204.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device lsi,id=scsi0,bus=pci.0,addr=0x4 -drive file=rbd:one/one-53-204-0:id=libvirt:key=...:auth_supported=cephx\;none:mon_host=kaffee.private.ungleich.ch\;wein.private.ungleich.ch\;tee.private.ungleich.ch,if=none,id=drive-scsi0-0-0,format=raw,cache=none -device scsi-hd,bus=scsi0.0,scsi-id=0,drive=drive-scsi0-0-0,id=scsi0-0-0,bootindex=1 -drive file=/var/lib/one//datastores/0/204/disk.1,if=none,id=drive-ide0-0-0,readonly=on,format=raw -device ide-cd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 -netdev tap,fd=24,id=hostnet0 -device rtl8139,netdev=hostnet0,id=net0,mac=02:00:4d:6d:96:ae,bus=pci.0,addr=0x3 -vnc 0.0.0.0:204 -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5

where

    -device lsi,id=scsi0,bus=pci.0,addr=0x4

is probably the relevant parameter.

Cheers,

Nico

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