Comment 3 for bug 2054218

Performing verification for mantic.

I deployed mantic onto a bare metal server, with kernel 6.5.0-26-generic from
-updates.

I installed a KVM stack, synced a cloud image, and tested VM creation.

$ uvt-kvm create --cpu 4 --memory 4096 --disk 10 jammy-a release=jammy arch=amd64
$ uvt-kvm ssh jammy-a
Welcome to Ubuntu 22.04.4 LTS (GNU/Linux 5.15.0-101-generic x86_64)

From there, I found the PID of the VM:

$ ps aux | grep qemu
libvirt+ 1799 107 1.5 9642380 1044752 ? Sl 03:21 0:38 /usr/bin/qemu-system-x86_64 -name guest=jammy-a,debug-threads=on -S -object {"qom-ty

We run perf:

$ sudo perf top -p 1799

$ virsh console jammy-a
Connected to domain 'jammy-a'
Escape character is ^] (Ctrl + ])
[ 161.413890] BUG: unable to handle page fault for address: fffffe18cdb1c028
[ 161.419474] #PF: supervisor read access in kernel mode
[ 161.423707] #PF: error_code(0x0000) - not-present page
[ 161.427949] PGD 17ffca0[ 161.429508] BUG: unable to handle page fault for address: fffffe18cdb1c028
[ 161.429513] #PF: supervisor read access in kernel mode
[ 161.429516] #PF: error_code(0x0000) - n

The VM suffers a page fault and crashes, and is not accessible over ssh.

$ uvt-kvm ssh jammy-a
(no response).

I then enabled -proposed, and installed 6.5.0-27-generic:

$ uname -rv
6.5.0-27-generic #28-Ubuntu SMP PREEMPT_DYNAMIC Thu Mar 7 18:21:00 UTC 2024

$ uvt-kvm create --cpu 4 --memory 4096 --disk 10 jammy-a release=jammy arch=amd64
$ uvt-kvm ssh jammy-a
Welcome to Ubuntu 22.04.4 LTS (GNU/Linux 5.15.0-101-generic x86_64)

We get the pid of the VM:

$ ps aux | grep qemu
libvirt+ 1786 42.5 1.5 7960876 1022308 ? Sl 03:37 0:40 /usr/bin/qemu-system-x86_64 -name guest=jammy-a,debug-threads=on -S -object {"qom-ty

We run perf:

$ sudo perf top -p 1786

This time, the VM does not crash, and stays running:

$ virsh console jammy-a
Connected to domain 'jammy-a'
Escape character is ^] (Ctrl + ])

jammy-a login:
jammy-a login:

We can also ssh to the VM just fine:

$ uvt-kvm ssh jammy-a
Welcome to Ubuntu 22.04.4 LTS (GNU/Linux 5.15.0-101-generic x86_64)

This is much better. The kernel in -proposed fixes the issue, happy to mark verified for mantic.