Sudden hang, no response to HOST+F

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Sudden hang, no response to HOST+F

Postby HarryMan » 12. Jan 2022, 09:34

I run some of my virtualbox VMs in full screen mode. One of them just had what looks like a hang, but I'm not really sure what was happening. I tried to HOST+F to get back to the host and look around a bit, but it did not work. I could move the mouse around inside the VM, and it seemed like I could open and close some of the applications, etc. But the only way to quit turned out to be getting a host console by ctrl-alt-Fx and terminating the VM, which is what I did. The log is attached.

At the time of the hang, I was just looking at email in thunderbird and viewing a web page in firefox. I will note that t-bird wanted to compact my inbox, but apparently felt I did not have sufficient disk space. I suppose that could point to a problem, or at least might exacerbate whatever is leading to these issues with vbox being unable to roll the menu down or close the VM. Still, I would hope that problems inside a VM would not interfere with vbox's operation generally.

A side note, but I think somewhat relevant: The past several versions of vbox in the 6.2x series especially, have been giving me an experience of stubborn or slow-witted responses to getting the menu to roll down (I have mine at the top of the screen). I keep it rolled up to avoid the menu overlaying the desktop panel, which is also at the top of the screen (usually, depending on the VM and how I've configured the desktop environment in that VM). The trouble is, sometimes the menu won't roll down at all, in which case I have to "feel around" with the mouse until I see a sliver of highlighting indicating the flat icon that closes the VM from the POV of the host desktop environment. Other times, I have to wait several seconds until it finally decides to roll down. Yet other times still, I find that if I switch between the VM and host a few times (2 or 3 usually), the behavior returns to something much more normal.

I'm running devuan beowulf on both host and guest. The host environment is XFCE4 4.12.2 and the guest is LXDE v.10.

As usual, thank you for your attention to this matter.
Attachments
myvm0-2022-01-11-22-56-51.log.gz
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HarryMan
 
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Re: Sudden hang, no response to HOST+F

Postby scottgus1 » 12. Jan 2022, 18:33

The VM was started from a saved state, which doesn't show all the diagnostic data in the VM:
Virtualbox Start Method (restoring = guest saved state):
22:29:27.275907 00:00:01.249928 Console: Machine state changed to 'Restoring'

If you have regular VM freezes, then please try posting a log when the VM has been fully shut down and started from cold power off.

I see lots of these, which I don't recognize:
06:48:28.909757 32:19:03.332021 AsyncCompletion: Task 0x007f8495e2acc0 completed after 16 seconds


We'll need a forum guru to look into this.
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Re: Sudden hang, no response to HOST+F

Postby HarryMan » 12. Jan 2022, 19:54

The trouble is, the VM had been up and running for some time prior. I am not sure if a cold-started VM will have the same scenario.

I looked at the previous log, but it seems to end a long time before the first message in the log I attached, above. It's odd, because I did not have the VM down for very long.
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Re: Sudden hang, no response to HOST+F

Postby scottgus1 » 12. Jan 2022, 19:58

HarryMan wrote:I am not sure if a cold-started VM will have the same scenario.

If the VM doesn't hang after a restart, that would be telling. Could be a mere glitch caused by any of the usual suspects: power fluctuations, cosmic rays, borrowers, you name it....
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Re: Sudden hang, no response to HOST+F

Postby HarryMan » 12. Jan 2022, 20:34

BTW, sometimes I see literally dozens of those Async error messages, on some VMs, at seemingly random times. Next time I witness it, I'll create a new topic and post the logs. I've seen other people have run into that also, but it is probably a different issue.
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Re: Sudden hang, no response to HOST+F

Postby fth0 » 13. Jan 2022, 20:28

The AsyncCompletion log messages could have to do with disk I/O delays on the host side. You could try if enabling the Host I/O Cache on the SATA Controller in the VM settings makes a difference.

Whenever you successfully switch to fullscreen or normal mode, you'll find a log message containing UIMachineViewFullscreen or UIMachineViewNormal in the VBox.log file. To eliminate the possibility that your host OS or any other program running on the host intercepts the HOST key, you could change it (I'm using LCTRL+LWIN+LALT, because no-one else is that crazy ;)).
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Re: Sudden hang, no response to HOST+F

Postby HarryMan » 22. Jan 2022, 14:44

It turned out that the non-responsive host key was due to the fact that it had somehow gotten re-set to the default. I had purposely set it to something else for a good reason; I had been working with RDP and needed to use a different key for the remote hosts.

Along with this auto-reset of the host key, I had also found virtualbox resetting the address of my hostonly interface on me. That happened several times. Now, it seems to have abated... but I have a funny feeling it will return. It has been doing that to me for weeks now.

I did NOT reset either the host key nor the hostonly interface address. I know it was not me because these had been working just fine and suddenly switched on me. Aside from ghosts in my machine, I cannot think of any reason they would re-set to your default for them.
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[SOLVED] Re: Sudden hang, no response to HOST+F

Postby HarryMan » 30. Apr 2022, 07:01

I am still not sure how the host key got changed on me, but for now, I'll just attribute that to those usual suspects you have already named (with the exception of power fluctuations, since all of my equipment is running through UPS units).

As for the host interface continually changing on me, I later discovered that there is a file we have to create now in recent versions of vbox (/etc/vbox/networks.conf) where overrides for the new default behavior can be set. This is documented (https://www.virtualbox.org/manual/UserManual.html#network_hostonly, scroll down to the end of section 6.5), but I had not recently re-read it to know that this had changed.
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