Re: early boot crash in init_tracer_tracefs

On Tue, Sep 29, 2026 at 09:36:05AM +0530, Amit Machhiwal wrote:

On 2026/09/28 11:43 AM, Amit Machhiwal wrote:

quoted

Hi Michal,

Thanks for the report.  We have been looking at the crash and have some findings
and follow-up questions.

On 2026/09/25 10:10 AM, Michal Suchánek wrote:

quoted

Hello,

There appears to be a regression between

< snip >

quoted

quoted

Linux 7.0.12
https://github.com/openSUSE/kernel/tree/4c9922875554ec191166ba6c0145f12d8ff9d4fc
https://github.com/openSUSE/kernel-source/blob/2ebf0bc/config/ppc64le/default

I have been trying to recreate the issue with this kernel and config but I
haven't been able to.  The L2 KVM guest boots fine everytime.

In addition to the requested information, could you please also share your qemu
cmdline/guest xml you used?

The XML of the VM is below. What other information do you require?

Thanks

Michal

<domain type='kvm'>
  <name>kwork2</name>
  <uuid>6b72d912-3243-48af-8cb2-b61f04b93ff2</uuid>
  <metadata>
    <libosinfo:libosinfo xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0">
      <libosinfo:os id="http://suse.com/sles/16"/>
    </libosinfo:libosinfo>
  </metadata>
  <memory unit='KiB'>260000000</memory>
  <currentMemory unit='KiB'>260000000</currentMemory>
  <vcpu placement='static'>120</vcpu>
  <os>
    <type arch='ppc64le' machine='pseries-10.0'>hvm</type>
    <boot dev='hd'/>
  </os>
  <cpu mode='custom' match='exact' check='none'>
    <model fallback='forbid'>POWER11</model>
  </cpu>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <devices>
    <emulator>/usr/bin/qemu-system-ppc64</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/scratch/libvirt/images/kwork2.qcow2'/>
      <blockio logical_block_size='4096' physical_block_size='4096'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <target dev='sda' bus='scsi'/>
      <readonly/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <controller type='usb' index='0' model='qemu-xhci' ports='15'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </controller>
    <controller type='scsi' index='0' model='virtio-scsi'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'>
      <model name='spapr-pci-host-bridge'/>
      <target index='0'/>
    </controller>
    <controller type='virtio-serial' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </controller>
    <interface type='bridge'>
      <mac address='52:54:00:94:23:7a'/>
      <source bridge='bridge'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
    </interface>
    <serial type='pty'>
      <target type='spapr-vio-serial' port='0'>
        <model name='spapr-vty'/>
      </target>
      <address type='spapr-vio' reg='0x30000000'/>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
      <address type='spapr-vio' reg='0x30000000'/>
    </console>
    <console type='pty'>
      <target type='virtio' port='1'/>
    </console>
    <channel type='unix'>
      <target type='virtio' name='org.qemu.guest_agent.0'/>
      <address type='virtio-serial' controller='0' bus='0' port='1'/>
    </channel>
    <audio id='1' type='none'/>
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </memballoon>
    <rng model='virtio'>
      <backend model='random'>/dev/urandom</backend>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    </rng>
    <panic model='pseries'/>
  </devices>
</domain>