[vfio-users] Host hard lockups

Thomas Lindroth thomas.lindroth at gmail.com
Sun Oct 16 19:52:31 UTC 2016

> It took longer than expected, but a definite crash happened yesterday.
> Sadly, it seems that MSI was not a fix for the in-use crashes.
> At this point I'm worried that it's some sort of weird hardware-specific
> interaction that is unlikely to be fixed. If anybody experiences similar
> symptoms or can suggest any debugging techniques, I'd greatly appreciate
> any suggestions.

I do experience something similar and have been since June. I get about 1-2
crashes per month and the symptoms are very similar to yours. After the last
crash I went ahead and setup netconsole logging. That way all kernel messages
are sent to another machine and are saved after the crash. 

It's easy to setup using the "Dynamic reconfiguration" solution but you'll
need another machine to log the messages.

Today I finally got another crash and it looks identical to this:

It's a problem with fuse that's only triggered under memory pressure. I
always assumed the crashes are related to kvm because it usually happens soon
after starting a VM but perhaps the VM only introduced the memory pressure
needed to trigger the fuse crash. Do you also use fuse?

The patch to fix it are marked <stable at vger.kernel.org> [3.15+] but so far
only 4.8.0 and above got the fix. I upgraded to 4.8.2 and hopefully that'll
fix the crashes for me.

After some googeling I even found this:
mergerfs is what I use fuse for.

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