I’ve Filed the Following Kernel Bug Report with Bugzilla.Kernel.Org regarding 5.19.x

2022-08-21 07:37:09 UTC
Created attachment 301614 [details]
The configuration file used to Comile this kernel.

This behavior has persisted across 5.19.0, 5.19.1, and 5.19.2.  While the kernel I am taking this example from is tainted (owing to using Intel development drivers for GPU virtualization), it is also occurring on non-tainted kernels on servers with no development or third party modules installed.

INFO: task CPU 2/KVM:2343 blocked for more than 1228 seconds.
[207177.050049]       Tainted: G     U    I       5.19.2 #1
[207177.050050] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[207177.050051] task:CPU 2/KVM       state:D stack:    0 pid: 2343 ppid:     1 flags:0x00000002
[207177.050054] Call Trace:
[207177.050055]  <TASK>
[207177.050056]  __schedule+0x359/0x1400
[207177.050060]  ? kvm_mmu_page_fault+0x1ee/0x980
[207177.050062]  ? kvm_set_msr_common+0x31f/0x1060
[207177.050065]  schedule+0x5f/0x100
[207177.050066]  schedule_preempt_disabled+0x15/0x30
[207177.050068]  __mutex_lock.constprop.0+0x4e2/0x750
[207177.050070]  ? aa_file_perm+0x124/0x4f0
[207177.050071]  __mutex_lock_slowpath+0x13/0x20
[207177.050072]  mutex_lock+0x25/0x30
[207177.050075]  intel_vgpu_emulate_mmio_read+0x5d/0x3b0 [kvmgt]
[207177.050084]  intel_vgpu_rw+0xb8/0x1c0 [kvmgt]
[207177.050091]  intel_vgpu_read+0x20d/0x250 [kvmgt]
[207177.050097]  vfio_device_fops_read+0x1f/0x40
[207177.050100]  vfs_read+0x9b/0x160
[207177.050102]  __x64_sys_pread64+0x93/0xd0
[207177.050104]  do_syscall_64+0x58/0x80
[207177.050106]  ? kvm_on_user_return+0x84/0xe0
[207177.050107]  ? fire_user_return_notifiers+0x37/0x70
[207177.050109]  ? exit_to_user_mode_prepare+0x41/0x200
[207177.050111]  ? syscall_exit_to_user_mode+0x1b/0x40
[207177.050112]  ? do_syscall_64+0x67/0x80
[207177.050114]  ? irqentry_exit+0x54/0x70
[207177.050115]  ? sysvec_call_function_single+0x4b/0xa0
[207177.050116]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
[207177.050118] RIP: 0033:0x7ff51131293f
[207177.050119] RSP: 002b:00007ff4ddffa260 EFLAGS: 00000293 ORIG_RAX: 0000000000000011
[207177.050121] RAX: ffffffffffffffda RBX: 00005599a6835420 RCX: 00007ff51131293f
[207177.050122] RDX: 0000000000000004 RSI: 00007ff4ddffa2a8 RDI: 0000000000000027
[207177.050123] RBP: 0000000000000004 R08: 0000000000000000 R09: 00000000ffffffff
[207177.050124] R10: 0000000000065f10 R11: 0000000000000293 R12: 0000000000065f10
[207177.050124] R13: 00005599a6835330 R14: 0000000000000004 R15: 0000000000065f10
[207177.050126]  </TASK>

     I am seeing this on Intel i7-6700k, i7-6850k, and i7-9700k platforms.

     This did not happen on 5.17 kernels, and 5.18 kernels never ran stable enough on my platforms to actually run them for more than a few minutes.

     Likewise 6.0-rc1 has not been stable enough to run in production.  After
less than three hours running on my workstation it locked hard with even the magic sys-request key being unresponsive and only power cycling the machine got it back.

     The operating system in use for the host on all machines is Ubuntu 22.04.

     Guests vary with Ubuntu 22.04 being the most common but also Mint, Debian, Manjaro, Centos, Fedora, ScientificLinux, Zorin, and Windows being in use.

     I see the same issue manifest on platforms running only Ubuntu guests as with guests of varying operating systems.  

     The configuration file I used to compile this kernel is attached.  I compiled it with gcc 12.1.0.

     This behavior does not manifest itself instantly, typically the machine needs to be running 3-7 days before it does.  Once it does guests keep stalling and restarting libvirtd does not help.  Only thing that seems to is a hard reboot of the physical host.  For this reason I believe the issue lies strictly with the host and not the guests.

     I have listed it as a severity of high since it is completely service interrupting.